
[Federal Register Volume 81, Number 58 (Friday, March 25, 2016)]
[Rules and Regulations]
[Pages 16285-16890]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-04800]



[[Page 16285]]

Vol. 81

Friday,

No. 58

March 25, 2016

Part II

Book 2 of 3 Books

Pages 16285-16890





Department of Labor





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Occupational Safety and Health Administration



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29 CFR Parts 1910, 1915, and 1926



Occupational Exposure to Respirable Crystalline Silica; Final Rule

  Federal Register / Vol. 81 , No. 58 / Friday, March 25, 2016 / Rules 
and Regulations  

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DEPARTMENT OF LABOR

Occupational Safety and Health Administration

29 CFR Parts 1910, 1915, and 1926

[Docket No. OSHA-2010-0034]
RIN 1218-AB70


Occupational Exposure to Respirable Crystalline Silica

AGENCY: Occupational Safety and Health Administration (OSHA), 
Department of Labor.

ACTION: Final rule.

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SUMMARY: The Occupational Safety and Health Administration (OSHA) is 
amending its existing standards for occupational exposure to respirable 
crystalline silica. OSHA has determined that employees exposed to 
respirable crystalline silica at the previous permissible exposure 
limits face a significant risk of material impairment to their health. 
The evidence in the record for this rulemaking indicates that workers 
exposed to respirable crystalline silica are at increased risk of 
developing silicosis and other non-malignant respiratory diseases, lung 
cancer, and kidney disease. This final rule establishes a new 
permissible exposure limit of 50 micrograms of respirable crystalline 
silica per cubic meter of air (50 [mu]g/m\3\) as an 8-hour time-
weighted average in all industries covered by the rule. It also 
includes other provisions to protect employees, such as requirements 
for exposure assessment, methods for controlling exposure, respiratory 
protection, medical surveillance, hazard communication, and 
recordkeeping.
    OSHA is issuing two separate standards--one for general industry 
and maritime, and the other for construction--in order to tailor 
requirements to the circumstances found in these sectors.

DATES: The final rule is effective on June 23, 2016. Start-up dates for 
specific provisions are set in Sec.  1910.1053(l) for general industry 
and maritime and in Sec.  1926.1153(k) for construction.

Collections of Information

    There are a number of collections of information contained in this 
final rule (see Section VIII, Paperwork Reduction Act). Notwithstanding 
the general date of applicability that applies to all other 
requirements contained in the final rule, affected parties do not have 
to comply with the collections of information until the Department of 
Labor publishes a separate notice in the Federal Register announcing 
the Office of Management and Budget has approved them under the 
Paperwork Reduction Act.

ADDRESSES: In accordance with 28 U.S.C. 2112(a), the Agency designates 
Ann Rosenthal, Associate Solicitor of Labor for Occupational Safety and 
Health, Office of the Solicitor of Labor, Room S-4004, U.S. Department 
of Labor, 200 Constitution Avenue NW., Washington, DC 20210, to receive 
petitions for review of the final rule.

FOR FURTHER INFORMATION CONTACT: For general information and press 
inquiries, contact Frank Meilinger, Director, Office of Communications, 
Room N-3647, OSHA, U.S. Department of Labor, 200 Constitution Avenue 
NW., Washington, DC 20210; telephone (202) 693-1999; email 
meilinger.francis2@dol.gov.
    For technical inquiries, contact William Perry or David O'Connor, 
Directorate of Standards and Guidance, Room N-3718, OSHA, U.S. 
Department of Labor, 200 Constitution Avenue NW., Washington, DC 20210; 
telephone (202) 693-1950.

SUPPLEMENTARY INFORMATION: The preamble to the rule on occupational 
exposure to respirable crystalline silica follows this outline:

I. Executive Summary
II. Pertinent Legal Authority
III. Events Leading to the Final Standards
IV. Chemical Properties and Industrial Uses
V. Health Effects
VI. Final Quantitative Risk Assessment and Significance of Risk
VII. Summary of the Final Economic Analysis and Final Regulatory 
Flexibility Analysis
VIII. Paperwork Reduction Act
IX. Federalism
X. State-Plan States
XI. Unfunded Mandates
XII. Protecting Children From Environmental Health and Safety Risks
XIII. Consultation and Coordination With Indian Tribal Governments
XIV. Environmental Impacts
XV. Summary and Explanation of the Standards
    Scope
    Definitions
    Specified Exposure Control Methods
    Alternative Exposure Control Methods
    Permissible Exposure Limit
    Exposure Assessment
    Regulated Areas
    Methods of Compliance
    Respiratory Protection
    Housekeeping
    Written Exposure Control Plan
    Medical Surveillance
    Communication of Respirable Crystalline Silica Hazards to 
Employees
    Recordkeeping
    Dates
Authority and Signature

Citation Method

    In the docket for the respirable crystalline silica rulemaking, 
found at http://www.regulations.gov, every submission was assigned a 
document identification (ID) number that consists of the docket number 
(OSHA-2010-0034) followed by an additional four-digit number. For 
example, the document ID number for OSHA's Preliminary Economic 
Analysis and Initial Regulatory Flexibility Analysis is OSHA-2010-0034-
1720. Some document ID numbers include one or more attachments, such as 
the National Institute for Occupational Safety and Health (NIOSH) 
prehearing submission (see Document ID OSHA 2010-0034-2177).
    When citing exhibits in the docket, OSHA includes the term 
``Document ID'' followed by the last four digits of the document ID 
number, the attachment number or other attachment identifier, if 
applicable, page numbers (designated ``p.'' or ``Tr.'' for pages from a 
hearing transcript), and in a limited number of cases a footnote number 
(designated ``Fn''). In a citation that contains two or more document 
ID numbers, the document ID numbers are separated by semi-colons. For 
example, a citation referring to the NIOSH prehearing comments and 
NIOSH testimony obtained from the hearing transcript would be indicated 
as follows: (Document ID 2177, Attachment B, pp. 2-3; 3579, Tr. 132). 
In some sections, such as Section V, Health Effects, author names and 
year of study publication are included before the document ID number in 
a citation, for example: (Hughes et al., 2001, Document ID 1060; 
McDonald et al., 2001, 1091; McDonald et al., 2005, 1092; Rando et al., 
2001, 0415).

I. Executive Summary

    This final rule establishes a permissible exposure limit (PEL) for 
respirable crystalline silica of 50 [mu]g/m\3\ as an 8-hour time-
weighted average (TWA) in all industries covered by the rule. In 
addition to the PEL, the rule includes provisions to protect employees 
such as requirements for exposure assessment, methods for controlling 
exposure, respiratory protection, medical surveillance, hazard 
communication, and recordkeeping. OSHA is issuing two separate 
standards--one for general industry and maritime, and the other for 
construction--in order to tailor requirements to the circumstances 
found in these sectors. There are, however, numerous common elements in 
the two standards.

[[Page 16287]]

    The final rule is based on the requirements of the Occupational 
Safety and Health Act (OSH Act) and court interpretations of the Act. 
For health standards issued under section 6(b)(5) of the OSH Act, OSHA 
is required to promulgate a standard that reduces significant risk to 
the extent that it is technologically and economically feasible to do 
so. See Section II, Pertinent Legal Authority, for a full discussion of 
OSH Act legal requirements.
    OSHA has conducted an extensive review of the literature on adverse 
health effects associated with exposure to respirable crystalline 
silica. OSHA has also developed estimates of the risk of silica-related 
diseases, assuming exposure over a working lifetime, at the preceding 
PELs as well as at the revised PEL and action level. Comments received 
on OSHA's preliminary analysis, and the Agency's final findings, are 
discussed in Section V, Health Effects, and Section VI, Final 
Quantitative Risk Assessment and Significance of Risk. OSHA finds that 
employees exposed to respirable crystalline silica at the preceding 
PELs are at an increased risk of lung cancer mortality and silicosis 
mortality and morbidity. Occupational exposures to respirable 
crystalline silica also result in increased risk of death from other 
nonmalignant respiratory diseases including chronic obstructive 
pulmonary disease (COPD), and from kidney disease. OSHA further 
concludes that exposure to respirable crystalline silica constitutes a 
significant risk of material impairment to health and that the final 
rule will substantially lower that risk. The Agency considers the level 
of risk remaining at the new PEL to be significant. However, based on 
the evidence evaluated during the rulemaking process, OSHA has 
determined a PEL of 50 [mu]g/m\3\ is appropriate because it is the 
lowest level feasible for all affected industries.
    OSHA's examination of the technological and economic feasibility of 
the rule is presented in the Final Economic Analysis and Final 
Regulatory Flexibility Analysis (FEA), and is summarized in Section VII 
of this preamble. OSHA concludes that the PEL of 50 [mu]g/m\3\ is 
technologically feasible for most operations in all affected 
industries, although it will be a technological challenge for several 
affected sectors and will require the use of respirators for a limited 
number of job categories and tasks.
    OSHA developed quantitative estimates of the compliance costs of 
the rule for each of the affected industry sectors. The estimated 
compliance costs were compared with industry revenues and profits to 
provide a screening analysis of the economic feasibility of complying 
with the rule and an evaluation of the economic impacts. Industries 
with unusually high costs as a percentage of revenues or profits were 
further analyzed for possible economic feasibility issues. After 
performing these analyses, OSHA finds that compliance with the 
requirements of the rule is economically feasible in every affected 
industry sector.
    The final rule includes several major changes from the proposed 
rule as a result of OSHA's analysis of comments and evidence received 
during the comment periods and public hearings. The major changes are 
summarized below and are fully discussed in Section XV, Summary and 
Explanation of the Standards.
    Scope. As proposed, the standards covered all occupational 
exposures to respirable crystalline silica with the exception of 
agricultural operations covered under 29 CFR part 1928. OSHA has made a 
final determination to exclude exposures in general industry and 
maritime where the employer has objective data demonstrating that 
employee exposure to respirable crystalline silica will remain below 25 
[mu]g/m\3\ as an 8-hour TWA under any foreseeable conditions. OSHA is 
also excluding exposures in construction where employee exposure to 
respirable crystalline silica will remain below 25 [mu]g/m\3\ as an 8-
hour TWA under any foreseeable conditions. In addition, OSHA is 
excluding exposures that result from the processing of sorptive clays 
from the scope of the rule. The standard for general industry and 
maritime also allows employers to comply with the standard for 
construction in certain circumstances.
    Specified Exposure Control Methods. OSHA has revised the structure 
of the standard for construction to emphasize the specified exposure 
control methods for construction tasks that are presented in Table 1 of 
the standard. Unlike in the proposed rule, employers who fully and 
properly implement the controls listed on Table 1 are not separately 
required to comply with the PEL, and are not subject to provisions for 
exposure assessment and methods of compliance. The entries on Table 1 
have also been revised extensively.
    Protective Clothing. The proposed rule would have required use of 
protective clothing in certain limited situations. The final rule does 
not include requirements for use of protective clothing to address 
exposure to respirable crystalline silica.
    Housekeeping. The proposed rule would have prohibited use of 
compressed air, dry sweeping, and dry brushing to clean clothing or 
surfaces contaminated with crystalline silica where such activities 
could contribute to employee exposure to respirable crystalline silica 
that exceeds the PEL. The final rule allows for use of compressed air, 
dry sweeping, and dry brushing in certain limited situations.
    Written Exposure Control Plan. OSHA did not propose a requirement 
for employers to develop a written exposure control plan. The final 
rule includes a requirement for employers covered by the rule to 
develop a written exposure control plan, and the standard for 
construction includes a provision for a competent person (i.e., a 
designated individual who is capable of identifying crystalline silica 
hazards in the workplace and who possesses the authority to take 
corrective measures to address them) to implement the written exposure 
control plan.
    Regulated Areas. OSHA proposed to provide employers covered by the 
rule with the alternative of either establishing a regulated area or an 
access control plan to limit access to areas where exposure to 
respirable crystalline silica exceeds the PEL. The final standard for 
general industry and maritime requires employers to establish a 
regulated area in such circumstances. The final standard for 
construction does not include a provision for regulated areas, but 
includes a requirement that the written exposure control plan include 
procedures used to restrict access to work areas, when necessary, to 
minimize the numbers of employees exposed to respirable crystalline 
silica and their level of exposure. The access control plan alternative 
is not included in the final rule.
    Medical Surveillance. The proposed rule would have required 
employers to make medical surveillance available to employees exposed 
to respirable crystalline silica above the PEL for 30 or more days per 
year. The final standard for general industry and maritime requires 
that medical surveillance be made available to employees exposed to 
respirable crystalline silica at or above the action level of 25 [mu]g/
m\3\ as an 8-hour TWA for 30 or more days per year. The final standard 
for construction requires that medical surveillance be made available 
to employees who are required by the standard to use respirators for 30 
or more days per year.
    The rule requires the employer to obtain a written medical opinion 
from physicians or other licensed health care professionals (PLHCPs) 
for medical

[[Page 16288]]

examinations provided under the rule but limits the information 
provided to the employer to the date of the examination, a statement 
that the examination has met the requirements of the standard, and any 
recommended limitations on the employee's use of respirators. The 
proposed rule would have required that such opinions contain additional 
information, without requiring employee authorization, such as any 
recommended limitations upon the employee's exposure to respirable 
crystalline silica, and any referral to a specialist. In the final 
rule, the written opinion provided to the employer will only include 
recommended limitations on the employee's exposure to respirable 
crystalline silica and referral to a specialist if the employee 
provides written authorization. The final rule requires a separate 
written medical report provided to the employee to include this 
additional information, as well as detailed information related to the 
employee's health.
    Dates. OSHA proposed identical requirements for both standards: an 
effective date 60 days after publication of the rule; a date for 
compliance with all provisions except engineering controls and 
laboratory requirements of 180 days after the effective date; a date 
for compliance with engineering controls requirements, which was one 
year after the effective date; and a date for compliance with 
laboratory requirements of two years after the effective date.
    OSHA has revised the proposed compliance dates in both standards. 
The final rule is effective 90 days after publication. For general 
industry and maritime, all obligations for compliance commence two 
years after the effective date, with two exceptions: The obligation for 
engineering controls commences five years after the effective date for 
hydraulic fracturing operations in the oil and gas industry; and the 
obligation for employers in general industry and maritime to offer 
medical surveillance commences two years after the effective date for 
employees exposed above the PEL, and four years after the effective 
date for employees exposed at or above the action level. For 
construction, all obligations for compliance commence one year after 
the effective date, with the exception that certain requirements for 
laboratory analysis commence two years after the effective date.
    Under the OSH Act's legal standard directing OSHA to set health 
standards based on findings of significant risk of material impairment 
and technological and economic feasibility, OSHA does not use cost-
benefit analysis to determine the PEL or other aspects of the rule. It 
does, however, determine and analyze costs and benefits for its own 
informational purposes and to meet certain Executive Order 
requirements, as discussed in Section VII. Summary of the Final 
Economic Analysis and Final Regulatory Flexibility Analysis and in the 
FEA. Table I-1--which is derived from material presented in Section VII 
of this preamble--provides a summary of OSHA's best estimate of the 
costs and benefits of the rule using a discount rate of 3 percent. As 
shown, the rule is estimated to prevent 642 fatalities and 918 
moderate-to-severe silicosis cases annually once it is fully effective, 
and the estimated cost of the rule is $1,030 million annually. Also as 
shown in Table I-1, the discounted monetized benefits of the rule are 
estimated to be $8.7 billion annually, and the rule is estimated to 
generate net benefits of approximately $7.7 billion annually.

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[GRAPHIC] [TIFF OMITTED] TR25MR16.000

II. Pertinent Legal Authority

    The purpose of the Occupational Safety and Health Act (29 U.S.C. 
651 et seq.) (``the Act'' or ``the OSH Act''), is ``to assure so far as 
possible every working man and woman in the Nation safe and healthful 
working conditions and to preserve our human resources'' (29 U.S.C. 
651(b)). To achieve this goal Congress authorized the Secretary of 
Labor (``the Secretary'') ``to set mandatory occupational safety and 
health standards applicable to businesses affecting interstate 
commerce'' (29 U.S.C. 651(b)(3); see 29 U.S.C. 654(a) (requiring 
employers to comply with OSHA standards), 655(a) (authorizing summary 
adoption of existing consensus and federal standards within two years 
of the Act's enactment), and 655(b) (authorizing promulgation, 
modification or revocation of standards pursuant to notice and 
comment)). The primary statutory provision relied upon by the Agency in 
promulgating health standards is section 6(b)(5) of the Act; other 
sections of the OSH Act, however, authorize the Occupational Safety and 
Health Administration (OSHA) to require labeling and other appropriate 
forms of warning, exposure assessment, medical examinations, and 
recordkeeping in its standards (29 U.S.C. 655(b)(5), 655(b)(7), 
657(c)).
    The Act provides that in promulgating standards dealing with toxic 
materials or harmful physical agents, such as respirable crystalline 
silica, the Secretary shall set the standard which ``most adequately 
assures, to the extent feasible, on the basis of the best available 
evidence, that no employee will suffer material impairment of health . 
. . even if such employee has regular exposure to the hazard dealt with 
by such standard for the period of his working life'' (29 U.S.C. 
655(b)(5)). Thus, ``[w]hen Congress passed the Occupational Safety and 
Health Act in 1970, it chose to place pre-eminent value on assuring 
employees a safe and healthful working environment, limited only by the 
feasibility of achieving such an environment'' (American Textile Mfrs. 
Institute, Inc. v. Donovan, 452 US 490, 541 (1981) (``Cotton Dust'')).
    OSHA proposed this new standard for respirable crystalline silica 
and conducted its rulemaking pursuant to

[[Page 16290]]

section 6(b)(5) of the Act ((29 U.S.C. 655(b)(5)). The preceding silica 
standard, however, was adopted under the Secretary's authority in 
section 6(a) of the OSH Act (29 U.S.C. 655(a)), to adopt national 
consensus and established Federal standards within two years of the 
Act's enactment (see 29 CFR 1910.1000 Table Z-1). Any rule that 
``differs substantially from an existing national consensus standard'' 
must ``better effectuate the purposes of this Act than the national 
consensus standard'' (29 U.S.C. 655(b)(8)). Several additional legal 
requirements arise from the statutory language in sections 3(8) and 
6(b)(5) of the Act (29 U.S.C. 652(8), 655(b)(5)). The remainder of this 
section discusses these requirements, which OSHA must consider and meet 
before it may promulgate this occupational health standard regulating 
exposure to respirable crystalline silica.

Material Impairment of Health

    Subject to the limitations discussed below, when setting standards 
regulating exposure to toxic materials or harmful physical agents, the 
Secretary is required to set health standards that ensure that ``no 
employee will suffer material impairment of health or functional 
capacity . . .'' (29 U.S.C. 655(b)(5)). OSHA has, under this section, 
considered medical conditions such as irritation of the skin, eyes, and 
respiratory system, asthma, and cancer to be material impairments of 
health. What constitutes material impairment in any given case is a 
policy determination on which OSHA is given substantial leeway. ``OSHA 
is not required to state with scientific certainty or precision the 
exact point at which each type of [harm] becomes a material 
impairment'' (AFL-CIO v. OSHA, 965 F.2d 962, 975 (11th Cir. 1992)). 
Courts have also noted that OSHA should consider all forms and degrees 
of material impairment--not just death or serious physical harm (AFL-
CIO, 965 F.2d at 975). Thus the Agency has taken the position that 
``subclinical'' health effects, which may be precursors to more serious 
disease, can be material impairments of health that OSHA should address 
when feasible (43 FR 52952, 52954 (11/14/78) (Preamble to the Lead 
Standard)).

Significant Risk

    Section 3(8) of the Act requires that workplace safety and health 
standards be ``reasonably necessary or appropriate to provide safe or 
healthful employment'' (29 U.S.C. 652(8)). The Supreme Court, in its 
decision on OSHA's benzene standard, interpreted section 3(8) to mean 
that ``before promulgating any standard, the Secretary must make a 
finding that the workplaces in question are not safe'' (Indus. Union 
Dep't, AFL-CIO v. Am. Petroleum Inst., 448 U.S. 607, 642 (1980) 
(plurality opinion) (``Benzene'')). The Court further described OSHA's 
obligation as requiring it to evaluate ``whether significant risks are 
present and can be eliminated or lessened by a change in practices'' 
(Benzene, 448 U.S. at 642). The Court's holding is consistent with 
evidence in the legislative record, with regard to section 6(b)(5) of 
the Act (29 U.S.C. 655(b)(5)), that Congress intended the Agency to 
regulate unacceptably severe occupational hazards, and not ``to 
establish a utopia free from any hazards'' or to address risks 
comparable to those that exist in virtually any occupation or workplace 
(116 Cong. Rec. 37614 (1970), Leg. Hist. 480-82). It is also consistent 
with Section 6(g) of the OSH Act, which states that, in determining 
regulatory priorities, ``the Secretary shall give due regard to the 
urgency of the need for mandatory safety and health standards for 
particular industries, trades, crafts, occupations, businesses, 
workplaces or work environments'' (29 U.S.C. 655(g)).
    The Supreme Court in Benzene clarified that OSHA has considerable 
latitude in defining significant risk and in determining the 
significance of any particular risk. The Court did not specify a means 
to distinguish significant from insignificant risks, but rather 
instructed OSHA to develop a reasonable approach to making its 
significant risk determination. The Court stated that ``[i]t is the 
Agency's responsibility to determine, in the first instance, what it 
considers to be a `significant' risk'' (Benzene, 448 U.S. at 655), and 
it did not ``express any opinion on the . . . difficult question of 
what factual determinations would warrant a conclusion that significant 
risks are present which make promulgation of a new standard reasonably 
necessary or appropriate'' (Benzene, 448 U.S. at 659). The Court 
stated, however, that the section 6(f) (29 U.S.C. 655(b)(f)) 
substantial evidence standard applicable to OSHA's significant risk 
determination does not require the Agency ``to support its finding that 
a significant risk exists with anything approaching scientific 
certainty'' (Benzene, 448 U.S. at 656). Rather, OSHA may rely on ``a 
body of reputable scientific thought'' to which ``conservative 
assumptions in interpreting the data . . . '' may be applied, ``risking 
error on the side of overprotection'' (Benzene, 448 U.S. at 656; see 
also United Steelworkers of Am., AFL-CIO-CLC v. Marshall, 647 F.2d 
1189, 1248 (D.C. Cir. 1980) (``Lead I'') (noting the Benzene Court's 
application of this principle to carcinogens and applying it to the 
lead standard, which was not based on carcinogenic effects)). OSHA may 
thus act with a ``pronounced bias towards worker safety'' in making its 
risk determinations (Bldg & Constr. Trades Dep't v. Brock, 838 F.2d 
1258, 1266 (D.C. Cir. 1988) (``Asbestos II'').
    The Supreme Court further recognized that what constitutes 
``significant risk'' is ``not a mathematical straitjacket'' (Benzene, 
448 U.S. at 655) and will be ``based largely on policy considerations'' 
(Benzene, 448 U.S. at 655 n.62). The Court gave the following example:

    If . . . the odds are one in a billion that a person will die 
from cancer by taking a drink of chlorinated water, the risk clearly 
could not be considered significant. On the other hand, if the odds 
are one in a thousand that regular inhalation of gasoline vapors 
that are 2% benzene will be fatal, a reasonable person might well 
consider the risk significant . . . (Benzene, 448 U.S. at 655).

    Following Benzene, OSHA has, in many of its health standards, 
considered the one-in-a-thousand metric when determining whether a 
significant risk exists. Moreover, as ``a prerequisite to more 
stringent regulation'' in all subsequent health standards, OSHA has, 
consistent with the Benzene plurality decision, based each standard on 
a finding of significant risk at the ``then prevailing standard'' of 
exposure to the relevant hazardous substance (Asbestos II, 838 F.2d at 
1263). Once a significant risk of material impairment of health is 
demonstrated, it is of no import that the incidence of the illness may 
be declining (see Nat'l Min. Assoc. v. Sec'y, U.S. Dep't of Labor, Nos. 
14-11942, 14-12163, slip op. at 80 (11th Cir. Jan. 25, 2016) 
(interpreting the Mine Act, 30 U.S.C. 811(a)(6)(A), which contains the 
same language as section 6(b)(5) of the OSH Act requiring the Secretary 
to set standards that assure no employee will suffer material 
impairment of health)).
    The Agency's final risk assessment is derived from existing 
scientific and enforcement data and its final conclusions are made only 
after considering all evidence in the rulemaking record. Courts 
reviewing the validity of these standards have uniformly held the 
Secretary to the significant risk standard first articulated by the 
Benzene plurality and have generally upheld the Secretary's significant 
risk determinations as supported by substantial evidence and ``a 
reasoned explanation for his policy

[[Page 16291]]

assumptions and conclusions'' (Asbestos II, 838 F.2d at 1266).
    Once OSHA makes its significant risk finding, the ``more stringent 
regulation'' (Asbestos II, 838 F.2d at 1263) it promulgates must be 
``reasonably necessary or appropriate'' to reduce or eliminate that 
risk, within the meaning of section 3(8) of the Act (29 U.S.C. 652(8)) 
and Benzene (448 U.S. at 642) (see Asbestos II, 838 F.2d at 1269). The 
courts have interpreted section 6(b)(5) of the OSH Act as requiring 
OSHA to set the standard that eliminates or reduces risk to the lowest 
feasible level; as discussed below, the limits of technological and 
economic feasibility usually determine where the new standard is set 
(see UAW v. Pendergrass, 878 F.2d 389, 390 (D.C. Cir. 1989)). In 
choosing among regulatory alternatives, however, ``[t]he determination 
that [one standard] is appropriate, as opposed to a marginally [more or 
less protective] standard, is a technical decision entrusted to the 
expertise of the agency. . . '' (Nat'l Mining Ass'n v. Mine Safety and 
Health Admin., 116 F.3d 520, 528 (D.C. Cir. 1997)) (analyzing a Mine 
Safety and Health Administration (``MSHA'') standard under the Benzene 
significant risk standard). In making its choice, OSHA may incorporate 
a margin of safety even if it theoretically regulates below the lower 
limit of significant risk (Nat'l Mining Ass'n, 116 F.3d at 528 (citing 
American Petroleum Inst. v. Costle, 665 F.2d 1176, 1186 (D.C. Cir. 
1982))).

Working Life Assumption

    The OSH Act requires OSHA to set the standard that most adequately 
protects employees against harmful workplace exposures for the period 
of their ``working life'' (29 U.S.C. 655(b)(5)). OSHA's longstanding 
policy is to define ``working life'' as constituting 45 years; thus, it 
assumes 45 years of exposure when evaluating the risk of material 
impairment to health caused by a toxic or hazardous substance. This 
policy is not based on empirical data that most employees are exposed 
to a particular hazard for 45 years. Instead, OSHA has adopted the 
practice to be consistent with the statutory directive that ``no 
employee'' suffer material impairment of health ``even if'' such 
employee is exposed to the hazard for the period of his or her working 
life (see 74 FR 44796 (8/31/09)). OSHA's policy was given judicial 
approval in a challenge to an OSHA standard that lowered the 
permissible exposure limit (PEL) for asbestos (Asbestos II, 838 F.2d at 
1264-1265). In that case, the petitioners claimed that the median 
duration of employment in the affected industry sectors was only five 
years. Therefore, according to petitioners, OSHA erred in assuming a 
45-year working life in calculating the risk of health effects caused 
by asbestos exposure. The D.C. Circuit disagreed, stating,

    Even if it is only the rare worker who stays with asbestos-
related tasks for 45 years, that worker would face a 64/1000 excess 
risk of contracting cancer; Congress clearly authorized OSHA to 
protect such a worker (Asbestos II, 838 F.2d at 1264-1265).

OSHA might calculate the health risks of exposure, and the related 
benefits of lowering the exposure limit, based on an assumption of a 
shorter working life, such as 25 years, but such estimates are for 
informational purposes only.

Best Available Evidence

    Section 6(b)(5) of the Act requires OSHA to set standards ``on the 
basis of the best available evidence'' and to consider the ``latest 
available scientific data in the field'' (29 U.S.C. 655(b)(5)). As 
noted above, the Supreme Court, in its Benzene decision, explained that 
OSHA must look to ``a body of reputable scientific thought'' in making 
its material harm and significant risk determinations, while noting 
that a reviewing court must ``give OSHA some leeway where its findings 
must be made on the frontiers of scientific knowledge'' (Benzene, 448 
U.S. at 656). The courts of appeals have afforded OSHA similar latitude 
to issue health standards in the face of scientific uncertainty. The 
Second Circuit, in upholding the vinyl chloride standard, stated:

    . . . the ultimate facts here in dispute are `on the frontiers 
of scientific knowledge', and, though the factual finger points, it 
does not conclude. Under the command of OSHA, it remains the duty of 
the Secretary to act to protect the workingman, and to act even in 
circumstances where existing methodology or research is deficient 
(Society of the Plastics Industry, Inc. v. OSHA, 509 F.2d 1301, 1308 
(2d Cir. 1975) (quoting Indus. Union Dep't, AFL-CIO v. Hodgson, 499 
F.2d 467, 474 (D.C. Cir. 1974) (``Asbestos I''))).

The D.C. Circuit, in upholding the cotton dust standard, stated: 
``OSHA's mandate necessarily requires it to act even if information is 
incomplete when the best available evidence indicates a serious threat 
to the health of workers'' (Am. Fed'n of Labor & Cong. of Indus. Orgs. 
v. Marshall, 617 F.2d 636, 651 (D.C. Cir. 1979), aff'd in part and 
vacated in part on other grounds, American Textile Mfrs. Inst., Inc. v. 
Donovan, 452 U.S. 490 (1981)).
    When there is disputed scientific evidence, OSHA must review the 
evidence on both sides and ``reasonably resolve'' the dispute (Pub. 
Citizen Health Research Grp. v. Tyson, 796 F.2d 1479, 1500 (D.C. Cir. 
1986)). In Public Citizen, there was disputed scientific evidence 
regarding whether there was a threshold exposure level for the health 
effects of ethylene oxide. The Court noted that, where ``OSHA has the 
expertise we lack and it has exercised that expertise by carefully 
reviewing the scientific data,'' a dispute within the scientific 
community is not occasion for it to take sides about which view is 
correct (Pub. Citizen Health Research Grp., 796 F.2d at 1500). 
``Indeed, Congress did `not [intend] that the Secretary be paralyzed by 
debate surrounding diverse medical opinions' '' (Pub. Citizen Health 
Research Grp., 796 F.2d at 1497 (quoting H.R.Rep. No. 91-1291, 91st 
Cong., 2d Sess. 18 (1970), reprinted in Legislative History of the 
Occupational Safety and Health Act of 1970 at 848 (1971))).
    A recent decision by the Eleventh Circuit Court of Appeals 
upholding a coal dust standard promulgated by MSHA emphasized that 
courts should give ``an extreme degree of deference to the agency when 
it is evaluating scientific data within its technical expertise'' 
(Nat'l Min. Assoc. v. Sec'y, U.S. Dep't of Labor, Nos. 14-11942, 14-
12163, slip op. at 43 (11th Cir. Jan. 25, 2016) (quoting Kennecott 
Greens Creek Min. Co. v. MSHA, 476 F.3d 946, 954-955 (D.C. Cir. 2007) 
(internal quotation marks omitted)). The Court emphasized that because 
the Mine Act, like the OSH Act, ``evinces a clear bias in favor of [ ] 
health and safety,'' the agency's responsibility to use the best 
evidence and consider feasibility should not be used as a counterweight 
to the agency's duty to protect the lives and health of workers (Nat'l 
Min. Assoc., Nos. 14-11942, 14-12163, slip op. at 43 (11th Cir. Jan. 
25, 2016)).

Feasibility

    The OSH Act requires that, in setting a standard, OSHA must 
eliminate the risk of material health impairment ``to the extent 
feasible'' (29 U.S.C. 655(b)(5)). The statutory mandate to consider the 
feasibility of the standard encompasses both technological and economic 
feasibility; these analyses have been done primarily on an industry-by-
industry basis (Lead I, 647 F.2d at 1264, 1301) in general industry. 
The Agency has also used application groups, defined by common tasks, 
as the structure for its feasibility analyses in construction (Pub. 
Citizen Health Research Grp. v. OSHA, 557 F.3d 165, 177-179 (3d Cir. 
2009) (``Chromium (VI)''). The Supreme Court has broadly defined 
feasible as ``capable of being

[[Page 16292]]

done'' (Cotton Dust, 452 U.S. at 509-510).
    Although OSHA must set the most protective PEL that the Agency 
finds to be technologically and economically feasible, it retains 
discretion to set a uniform PEL even when the evidence demonstrates 
that certain industries or operations could reasonably be expected to 
meet a lower PEL. OSHA health standards generally set a single PEL for 
all affected employers; OSHA exercised this discretion most recently in 
its final rule on occupational exposure to chromium (VI) (71 FR 10100, 
10337-10338 (2/28/2006); see also 62 FR 1494, 1575 (1/10/97) (methylene 
chloride)). In its decision upholding the chromium (VI) standard, 
including the uniform PEL, the Court of Appeals for the Third Circuit 
addressed this issue as one of deference, stating ``OSHA's decision to 
select a uniform exposure limit is a legislative policy decision that 
we will uphold as long as it was reasonably drawn from the record'' 
(Chromium (VI), 557 F.3d at 183 (3d Cir. 2009)); see also Am. Iron & 
Steel Inst. v. OSHA, 577 F.2d 825, 833 (3d Cir. 1978)). OSHA's reasons 
for choosing one chromium (VI) PEL, rather than imposing different PELs 
on different application groups or industries, included: Multiple PELs 
would create enforcement and compliance problems because many 
workplaces, and even workers, were affected by multiple categories of 
chromium (VI) exposure; discerning individual PELs for different groups 
of establishments would impose a huge evidentiary burden on the Agency 
and unnecessarily delay implementation of the standard; and a uniform 
PEL would, by eliminating confusion and simplifying compliance, enhance 
worker protection (Chromium (VI), 557 F.3d at 173, 183-184). The Court 
held that OSHA's rationale for choosing a uniform PEL, despite evidence 
that some application groups or industries could meet a lower PEL, was 
reasonably drawn from the record and that the Agency's decision was 
within its discretion and supported by past practice (Chromium (VI), 
557 F.3d at 183-184).

Technological Feasibility

    A standard is technologically feasible if the protective measures 
it requires already exist, can be brought into existence with available 
technology, or can be created with technology that can reasonably be 
expected to be developed (Lead I, 647 F.2d at 1272; Amer. Iron & Steel 
Inst. v. OSHA, 939 F.2d 975, 980 (D.C. Cir. 1991) (``Lead II'')). While 
the test for technological feasibility is normally articulated in terms 
of the ability of employers to decrease exposures to the PEL, 
provisions such as exposure measurement requirements must also be 
technologically feasible (Forging Indus. Ass'n v. Sec'y of Labor, 773 
F.2d 1436, 1453 (4th Cir. 1985)).
    OSHA's standards may be ``technology forcing,'' i.e., where the 
Agency gives an industry a reasonable amount of time to develop new 
technologies, OSHA is not bound by the ``technological status quo'' 
(Lead I, 647 F.2d at 1264); see also Kennecott Greens Creek Min. Co. v. 
MSHA, 476 F.3d 946, 957 (D.C. Cir. 2007) (MSHA standards, like OSHA 
standards, may be technology-forcing); Nat'l Petrochemical & Refiners 
Ass'n v. EPA, 287 F.3d 1130, 1136 (D.C. Cir. 2002) (agency is ``not 
obliged to provide detailed solutions to every engineering problem,'' 
but only to ``identify the major steps for improvement and give 
plausible reasons for its belief that the industry will be able to 
solve those problems in the time remaining.'').
    In its Lead decisions, the D.C. Circuit described OSHA's obligation 
to demonstrate the technological feasibility of reducing occupational 
exposure to a hazardous substance.

    [W]ithin the limits of the best available evidence . . . OSHA 
must prove a reasonable possibility that the typical firm will be 
able to develop and install engineering and work practice controls 
that can meet the PEL in most of its operations . . . The effect of 
such proof is to establish a presumption that industry can meet the 
PEL without relying on respirators . . . Insufficient proof of 
technological feasibility for a few isolated operations within an 
industry, or even OSHA's concession that respirators will be 
necessary in a few such operations, will not undermine this general 
presumption in favor of feasibility. Rather, in such operations 
firms will remain responsible for installing engineering and work 
practice controls to the extent feasible, and for using them to 
reduce . . . exposure as far as these controls can do so (Lead I, 
647 F.2d at 1272).

    Additionally, the D.C. Circuit explained that ``[f]easibility of 
compliance turns on whether exposure levels at or below [the PEL] can 
be met in most operations most of the time . . .'' (Lead II, 939 F.2d 
at 990).
    Courts have given OSHA significant deference in reviewing its 
technological feasibility findings.

    So long as we require OSHA to show that any required means of 
compliance, even if it carries no guarantee of meeting the PEL, will 
substantially lower . . . exposure, we can uphold OSHA's 
determination that every firm must exploit all possible means to 
meet the standard (Lead I, 647 F.2d at 1273).

    Even in the face of significant uncertainty about technological 
feasibility in a given industry, OSHA has been granted broad discretion 
in making its findings (Lead I, 647 F.2d at 1285).

    OSHA cannot let workers suffer while it awaits . . . scientific 
certainty. It can and must make reasonable [technological 
feasibility] predictions on the basis of `credible sources of 
information,' whether data from existing plants or expert testimony 
(Lead I, 647 F.2d at 1266 (quoting Am. Fed'n of Labor & Cong. of 
Indus. Orgs., 617 F.2d at 658)).

    For example, in Lead I, the D.C. Circuit allowed OSHA to use, as 
best available evidence, information about new and expensive industrial 
smelting processes that had not yet been adopted in the U.S. and would 
require the rebuilding of plants (Lead I, 647 F.2d at 1283-1284). Even 
under circumstances where OSHA's feasibility findings were less certain 
and the Agency was relying on its ``legitimate policy of technology 
forcing,'' the D.C. Circuit approved of OSHA's feasibility findings 
when the Agency granted lengthy phase-in periods to allow particular 
industries time to comply (Lead I, 647 F.2d at 1279-1281, 1285).
    OSHA is permitted to adopt a standard that some employers will not 
be able to meet some of the time, with employers limited to challenging 
feasibility at the enforcement stage (Lead I, 647 F.2d at 1273 & n. 
125; Asbestos II, 838 F.2d at 1268). Even when the Agency recognized 
that it might have to balance its general feasibility findings with 
flexible enforcement of the standard in individual cases, the courts of 
appeals have generally upheld OSHA's technological feasibility findings 
(Lead II, 939 F.2d at 980; see Lead I, 647 F.2d at 1266-1273; Asbestos 
II, 838 F.2d at 1268). Flexible enforcement policies have been approved 
where there is variability in measurement of the regulated hazardous 
substance or where exposures can fluctuate uncontrollably (Asbestos II, 
838 F.2d at 1267-1268; Lead II, 939 F.2d at 991). A common means of 
dealing with the measurement variability inherent in sampling and 
analysis is for the Agency to add the standard sampling error to its 
exposure measurements before determining whether to issue a citation 
(e.g., 51 FR 22612, 22654 (06/20/86) (Preamble to the Asbestos 
Standard)).

Economic Feasibility

    In addition to technological feasibility, OSHA is required to 
demonstrate that its standards are economically feasible. A reviewing 
court will examine the cost of compliance with an OSHA standard ``in 
relation to the financial health and

[[Page 16293]]

profitability of the industry and the likely effect of such costs on 
unit consumer prices . . .'' (Lead I, 647 F.2d at 1265 (omitting 
citation)). As articulated by the D.C. Circuit in Lead I,

    OSHA must construct a reasonable estimate of compliance costs 
and demonstrate a reasonable likelihood that these costs will not 
threaten the existence or competitive structure of an industry, even 
if it does portend disaster for some marginal firms (Lead I, 647 
F.2d at 1272).

    A reasonable estimate entails assessing ``the likely range of costs 
and the likely effects of those costs on the industry'' (Lead I, 647 
F.2d at 1266). As with OSHA's consideration of scientific data and 
control technology, however, the estimates need not be precise (Cotton 
Dust, 452 U.S. at 528-29 & n.54) as long as they are adequately 
explained. Thus, as the D.C. Circuit further explained:


    Standards may be economically feasible even though, from the 
standpoint of employers, they are financially burdensome and affect 
profit margins adversely. Nor does the concept of economic 
feasibility necessarily guarantee the continued existence of 
individual employers. It would appear to be consistent with the 
purposes of the Act to envisage the economic demise of an employer 
who has lagged behind the rest of the industry in protecting the 
health and safety of employees and is consequently financially 
unable to comply with new standards as quickly as other employers. 
As the effect becomes more widespread within an industry, the 
problem of economic feasibility becomes more pressing (Asbestos I, 
499 F.2d. at 478).

    OSHA standards therefore satisfy the economic feasibility criterion 
even if they impose significant costs on regulated industries so long 
as they do not cause massive economic dislocations within a particular 
industry or imperil the very existence of the industry (Lead II, 939 
F.2d at 980; Lead I, 647 F.2d at 1272; Asbestos I, 499 F.2d. at 478). 
As with its other legal findings, OSHA ``is not required to prove 
economic feasibility with certainty, but is required to use the best 
available evidence and to support its conclusions with substantial 
evidence'' (Lead II, 939 F.2d at 980-981) (citing Lead I, 647 F.2d at 
1267)). Granting industries additional time to comply with new PELs may 
enhance the economic, as well as technological, feasibility of a 
standard (Lead I, 647 F.2d at 1265).
    Because section 6(b)(5) of the Act explicitly imposes the ``to the 
extent feasible'' limitation on the setting of health standards, OSHA 
is not permitted to use cost-benefit analysis to make its standards-
setting decisions (29 U.S.C. 655(b)(5)).

    Congress itself defined the basic relationship between costs and 
benefits, by placing the ``benefit'' of worker health above all 
other considerations save those making attainment of this 
``benefit'' unachievable. Any standard based on a balancing of costs 
and benefits by the Secretary that strikes a different balance than 
that struck by Congress would be inconsistent with the command set 
forth in Sec.  6(b)(5) (Cotton Dust, 452 U.S. at 509).

    Thus, while OSHA estimates the costs and benefits of its proposed 
and final rules, these calculations do not form the basis for the 
Agency's regulatory decisions; rather, they are performed in 
acknowledgement of requirements such as those in Executive Orders 12866 
and 13563.

Structure of OSHA Health Standards

    OSHA's health standards traditionally incorporate a comprehensive 
approach to reducing occupational disease. OSHA substance-specific 
health standards generally include the ``hierarchy of controls,'' 
which, as a matter of OSHA's preferred policy, mandates that employers 
install and implement all feasible engineering and work practice 
controls before respirators may be used. The Agency's adherence to the 
hierarchy of controls has been upheld by the courts (ASARCO, Inc. v. 
OSHA, 746 F.2d 483, 496-498 (9th Cir. 1984); Am. Iron & Steel Inst. v. 
OSHA, 182 F.3d 1261, 1271 (11th Cir. 1999)). In fact, courts view the 
legal standard for proving technological feasibility as incorporating 
the hierarchy:

    OSHA must prove a reasonable possibility that the typical firm 
will be able to develop and install engineering and work practice 
controls that can meet the PEL in most of its operations. . . . The 
effect of such proof is to establish a presumption that industry can 
meet the PEL without relying on respirators (Lead I, 647 F.2d at 
1272).

    The hierarchy of controls focuses on removing harmful materials at 
their source. OSHA allows employers to rely on respiratory protection 
to protect their employees only when engineering and work practice 
controls are insufficient or infeasible. In fact, in the control of 
``those occupational diseases caused by breathing air contaminated with 
harmful dusts, fogs, fumes, mists, gases, smokes, sprays, or vapors,'' 
the employers' primary objective ``shall be to prevent atmospheric 
contamination. This shall be accomplished as far as feasible by 
accepted engineering control measures (for example, enclosure or 
confinement of the operation, general and local ventilation, and 
substitution of less toxic materials). When effective engineering 
controls are not feasible, or while they are being instituted, 
appropriate respirators shall be used pursuant to this section'' (29 
CFR 1910.134).
    The reasons supporting OSHA's continued reliance on the hierarchy 
of controls, as well as its reasons for limiting the use of 
respirators, are numerous and grounded in good industrial hygiene 
principles (see Section XV, Summary and Explanation of the Standards, 
Methods of Compliance). Courts have upheld OSHA's emphasis on 
engineering and work practice controls over personal protective 
equipment in challenges to previous health standards, such as chromium 
(VI): ``Nothing in . . . any case reviewing an airborne toxin standard, 
can be read to support a technological feasibility rule that would 
effectively encourage the routine and widespread use of respirators to 
comply with a PEL'' (Chromium (VI), 557 F.3d at 179; see Am. Fed'n of 
Labor & Cong. of Indus. Orgs. v. Marshall, 617 F.2d 636, 653 (D.C. Cir. 
1979) cert. granted, judgment vacated sub nom. Cotton Warehouse Ass'n 
v. Marshall, 449 U.S. 809 (1980) and aff'd in part, vacated in part sub 
nom. Am. Textile Mfrs. Inst., Inc. v. Donovan, 452 U.S. 490 (1981) 
(finding ``uncontradicted testimony in the record that respirators can 
cause severe physical discomfort and create safety problems of their 
own'')).
    In health standards such as this one, the hierarchy of controls is 
augmented by ancillary provisions. These provisions work with the 
hierarchy of controls and personal protective equipment requirements to 
provide comprehensive protection to employees in affected workplaces. 
Such provisions typically include exposure assessment, medical 
surveillance, hazard communication, and recordkeeping. This approach is 
recognized as effective in dealing with air contaminants such as 
respirable crystalline silica; for example, the industry standards for 
respirable crystalline silica, ASTM E 1132-06, Standard Practice for 
Health Requirements Relating to Occupational Exposure to Respirable 
Crystalline Silica, and ASTM E 2626-09, Standard Practice for 
Controlling Occupational Exposure to Respirable Crystalline Silica for 
Construction and Demolition Activities, take a similar comprehensive 
approach (Document ID 1466; 1504).
    The OSH Act compels OSHA to require all feasible measures for 
reducing significant health risks (29 U.S.C. 655(b)(5); Pub. Citizen 
Health Research Grp., 796 F.2d at 1505 (``if in fact a STEL [short-term 
exposure limit] would further reduce a significant

[[Page 16294]]

health risk and is feasible to implement, then the OSH Act compels the 
agency to adopt it (barring alternative avenues to the same result)''). 
When there is significant risk below the PEL, as is the case with 
respirable crystalline silica, the DC Circuit indicated that OSHA 
should use its regulatory authority to impose additional requirements 
on employers when those requirements will result in a greater than de 
minimis incremental benefit to workers' health (Asbestos II, 838 F.2d 
at 1274). The Supreme Court alluded to a similar issue in Benzene, 
pointing out that ``in setting a permissible exposure level in reliance 
on less-than-perfect methods, OSHA would have the benefit of a backstop 
in the form of monitoring and medical testing'' (Benzene, 448 U.S. at 
657). OSHA believes that the ancillary provisions in this final 
standard provide significant benefits to worker health by providing 
additional layers and types of protection to employees exposed to 
respirable crystalline silica.
    Finally, while OSHA is bound by evidence in the rulemaking record, 
and generally looks to its prior standards for guidance on how to 
structure and specify requirements in a new standard, it is not limited 
to past approaches to regulation. In promulgating health standards, 
``[w]henever practicable, the standard promulgated shall be expressed 
in terms of objective criteria and of the performance desired'' (29 
U.S.C. 655(b)(5)). In cases of industries or tasks presenting unique 
challenges in terms of assessing and controlling exposures, it may be 
more practicable and provide greater certainty to require specific 
controls with a demonstrated track record of efficacy in reducing 
exposures and, therefore, risk (especially when supplemented by 
appropriate respirator usage). Such an approach could more effectively 
protect workers than the traditional exposure assessment-and-control 
approach when exposures may vary because of factors such as changing 
environmental conditions or materials, and an assessment may not 
reflect typical exposures associated with a task or operation. As 
discussed at length in Section XV, Summary and Explanation of the 
Standards, the specified exposure control measures option in the 
construction standard (i.e., Table 1, in paragraph (c)(1)) for 
respirable crystalline silica represents the type of innovative, 
objective approach available to the Secretary when fashioning a rule 
under these circumstances.

III. Events Leading to the Final Standards

    The Occupational Safety and Health Administration's (OSHA's) 
previous standards for workplace exposure to respirable crystalline 
silica were adopted in 1971, pursuant to section 6(a) of the 
Occupational Safety and Health Act (29 U.S.C. 651 et seq.) (``the Act'' 
or ``the OSH Act'') (36 FR 10466 (5/29/71)). Section 6(a) (29 U.S.C. 
655(a)) authorized OSHA, in the first two years after the effective 
date of the Act, to promulgate ``start-up'' standards, on an expedited 
basis and without public hearing or comment, based on national 
consensus or established Federal standards that improved employee 
safety or health. Pursuant to that authority, OSHA in 1971 promulgated 
approximately 425 permissible exposure limits (PELs) for air 
contaminants, including crystalline silica, which were derived 
principally from Federal standards applicable to government contractors 
under the Walsh-Healey Public Contracts Act, 41 U.S.C. 35, and the 
Contract Work Hours and Safety Standards Act (commonly known as the 
Construction Safety Act), 40 U.S.C. 333. The Walsh-Healey Act and 
Construction Safety Act standards had been adopted primarily from 
recommendations of the American Conference of Governmental Industrial 
Hygienists (ACGIH).
    For general industry (see 29 CFR 1910.1000, Table Z-3), the PEL for 
crystalline silica in the form of respirable quartz was based on two 
alternative formulas: (1) A particle-count formula, 
PELmppcf=250/(% quartz + 5) as respirable dust; and (2) a 
mass formula proposed by ACGIH in 1968, PEL=(10 mg/m3)/(% 
quartz + 2) as respirable dust. The general industry PELs for 
crystalline silica in the form of cristobalite and tridymite were one-
half of the value calculated from either of the above two formulas for 
quartz. For construction (see 29 CFR 1926.55, Appendix A) and shipyards 
(see 29 CFR 1915.1000, Table Z), the formula for the PEL for 
crystalline silica in the form of quartz (PELmppcf=250/(% 
quartz + 5) as respirable dust), which requires particle counting, was 
derived from the 1970 ACGIH threshold limit value (TLV).\1\ Based on 
the formulas, the PELs for quartz, expressed as time-weighted averages 
(TWAs), were approximately equivalent to 100 [mu]g/m3 for 
general industry and 250 [mu]g/m3 for construction and 
shipyards. The PELs were not supplemented by additional protective 
provisions--such as medical surveillance requirements--as are included 
in other OSHA standards. OSHA believes that the formula based on 
particle-counting technology used in the general industry, 
construction, and shipyard PELs has been rendered obsolete by 
respirable mass (gravimetric) sampling.
---------------------------------------------------------------------------

    \1\ The Mineral Dusts tables that contain the silica PELs for 
construction and shipyards do not clearly express PELs for 
cristobalite and tridymite. 29 CFR 1926.55; 29 CFR 1915.1000. This 
lack of textual clarity likely results from a transcription error in 
the Code of Federal Regulations. OSHA's final rule provides the same 
PEL for quartz, cristobalite, and tridymite in general industry, 
maritime, and construction.
---------------------------------------------------------------------------

    In 1974, the National Institute for Occupational Safety and Health 
(NIOSH), an agency within the Department of Health and Human Services 
created by the OSH Act and designed to carry out research and recommend 
standards for occupational safety and health hazards, evaluated 
crystalline silica as a workplace hazard and issued criteria for a 
recommended standard (29 U.S.C. 669, 671; Document ID 0388). NIOSH 
recommended that occupational exposure to crystalline silica be 
controlled so that no worker is exposed to a TWA of free (respirable 
crystalline) silica greater than 50 [mu]g/m3 as determined 
by a full-shift sample for up to a 10-hour workday over a 40-hour 
workweek. The document also recommended a number of ancillary 
provisions for a standard, such as exposure monitoring and medical 
surveillance.
    In December 1974, OSHA published an Advance Notice of Proposed 
Rulemaking (ANPRM) based on the recommendations in the NIOSH criteria 
document (39 FR 44771 (12/27/74)). In the ANPRM, OSHA solicited 
``public participation on the issues of whether a new standard for 
crystalline silica should be issued on the basis of the [NIOSH] 
criteria or any other information, and, if so, what should be the 
contents of a proposed standard for crystalline silica'' (39 FR at 
44771). OSHA also set forth the particular issues of concern on which 
comments were requested. The Agency did not issue a proposed rule or 
pursue a final rule for crystalline silica at that time.
    As information on the health effects of silica exposure developed 
during the 1980s and 1990s, national and international classification 
organizations came to recognize crystalline silica as a human 
carcinogen. In June 1986, the International Agency for Research on 
Cancer (IARC), which is the specialized cancer agency within the World 
Health Organization, evaluated the available evidence regarding 
crystalline silica carcinogenicity and concluded, in 1987, that 
crystalline silica is probably carcinogenic to

[[Page 16295]]

humans (http://monographs.iarc.fr/ENG/Monographs/suppl7/Suppl7.pdf). An 
IARC working group met again in October 1996 to evaluate the complete 
body of research, including research that had been conducted since the 
initial 1986 evaluation. IARC concluded, more decisively this time, 
that ``crystalline silica inhaled in the form of quartz or cristobalite 
from occupational sources is carcinogenic to humans'' (Document ID 
2258, Attachment 8, p. 211). In 2012, IARC reaffirmed that 
``Crystalline silica in the form of quartz or cristobalite dust is 
carcinogenic to humans'' (Document ID 1473, p. 396).
    In 1991, in the Sixth Annual Report on Carcinogens, the U.S. 
National Toxicology Program (NTP), within the U.S. Department of Health 
and Human Services, concluded that respirable crystalline silica was 
``reasonably anticipated to be a human carcinogen'' (as referenced in 
Document ID 1417, p. 1). NTP reevaluated the available evidence and 
concluded, in the Ninth Report on Carcinogens, that ``respirable 
crystalline silica (RCS), primarily quartz dust occurring in industrial 
and occupational settings, is known to be a human carcinogen, based on 
sufficient evidence of carcinogenicity from studies in humans 
indicating a causal relationship between exposure to RCS and increased 
lung cancer rates in workers exposed to crystalline silica dust'' 
(Document ID 1417, p. 1). ACGIH listed respirable crystalline silica 
(in the form of quartz) as a suspected human carcinogen in 2000, while 
lowering the TLV to 0.05 mg/m3 (50 [mu]g/m3) 
(Document ID 1503, p. 15). ACGIH subsequently lowered the TLV for 
crystalline silica to 0.025 mg/m3 (25 [mu]g/m3) 
in 2006, which is ACGIH's current recommended exposure limit (Document 
ID 1503, pp. 1, 15).
    In 1989, OSHA established 8-hour TWA PELs of 0.1 mg/m3 
(100 [mu]g/m3) for quartz and 0.05 mg/m3 (50 
[mu]g/m3) for cristobalite and tridymite, as part of the Air 
Contaminants final rule for general industry (54 FR 2332 (1/19/89)). 
OSHA stated that these limits presented no substantial change from the 
Agency's former formula limits, but would simplify sampling procedures. 
In providing comments on the proposed rule, NIOSH recommended that 
crystalline silica be considered a potential carcinogen.
    In 1992, OSHA, as part of the Air Contaminants proposed rule for 
maritime, construction, and agriculture, proposed the same PELs as for 
general industry, to make the PELs consistent across all the OSHA-
regulated sectors (57 FR 26002 (6/12/92)). However, the U.S. Court of 
Appeals for the Eleventh Circuit vacated the 1989 Air Contaminants 
final rule for general industry (Am. Fed'n of Labor and Cong. of Indus. 
Orgs. v. OSHA, 965 F.2d 962 (1992)), and also mooted the proposed rule 
for maritime, construction, and agriculture. The Court's decision to 
vacate the rule forced the Agency to return to the original 1971 PELs 
for all compounds, including silica, adopted as section 6(a) standards.
    In 1994, OSHA initiated a process to determine which safety and 
health hazards in the U.S. needed the most attention. A priority 
planning committee included safety and health experts from OSHA, NIOSH, 
and the Mine Safety and Health Administration (MSHA). The committee 
reviewed available information on occupational deaths, injuries, and 
illnesses and communicated extensively with representatives of labor, 
industry, professional and academic organizations, the States, 
voluntary standards organizations, and the public. The OSHA National 
Advisory Committee on Occupational Safety and Health and the Advisory 
Committee on Construction Safety and Health (ACCSH) also made 
recommendations. Rulemaking for crystalline silica exposure was one of 
the priorities designated by this process. OSHA indicated that 
crystalline silica would be added to the Agency's regulatory agenda as 
other standards were completed and resources became available.
    In 1996, OSHA instituted a Special Emphasis Program (SEP) to step 
up enforcement of the crystalline silica standards. The SEP was 
intended to reduce worker silica dust exposures that can cause 
silicosis and lung cancer. It included extensive outreach designed to 
educate and train employers and employees about the hazards of silica 
and how to control them, as well as inspections to enforce the 
standards. Among the outreach materials available were slides 
presenting information on hazard recognition and crystalline silica 
control technology, a video on crystalline silica and silicosis, and 
informational cards for workers explaining crystalline silica, health 
effects related to exposure, and methods of control. The SEP provided 
guidance for targeting inspections of worksites that had employees at 
risk of developing silicosis. The inspections resulted in the 
collection of exposure data from the various worksites visited by 
OSHA's compliance officers.
    As a follow-up to the SEP, OSHA undertook numerous non-regulatory 
actions to address silica exposures. For example, in October of 1996, 
OSHA launched a joint silicosis prevention effort with MSHA, NIOSH, and 
the American Lung Association (see https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=NEWS_RELEASES&p_id=14110). This public 
education campaign involved distribution of materials on how to prevent 
silicosis, including a guide for working safely with silica and 
stickers for hard hats to remind workers of crystalline silica hazards. 
Spanish language versions of these materials were also made available. 
OSHA and MSHA inspectors distributed materials at mines, construction 
sites, and other affected workplaces. The joint silicosis prevention 
effort included a National Conference to Eliminate Silicosis in 
Washington, DC, in March of 1997, which brought together approximately 
650 participants from labor, business, government, and the health and 
safety professions to exchange ideas and share solutions regarding the 
goal of eliminating silicosis (see https://industrydocuments.library.ucsf.edu/documentstore/s/h/d/p//shdp0052/shdp0052.pdf).
    In 1997, OSHA announced in its Unified Agenda under Long-Term 
Actions that it planned to publish a proposed rule on crystalline 
silica

    . . . because the agency has concluded that there will be no 
significant progress in the prevention of silica-related diseases 
without the adoption of a full and comprehensive silica standard, 
including provisions for product substitution, engineering controls, 
training and education, respiratory protection and medical screening 
and surveillance. A full standard will improve worker protection, 
ensure adequate prevention programs, and further reduce silica-
related diseases (62 FR 57755, 57758 (10/29/97)).

    In November 1998, OSHA moved ``Occupational Exposure to Crystalline 
Silica'' to the pre-rule stage in the Regulatory Plan (63 FR 61284, 
61303-61304 (11/9/98)). OSHA held a series of stakeholder meetings in 
1999 and 2000 to get input on the rulemaking. Stakeholder meetings for 
all industry sectors were held in Washington, Chicago, and San 
Francisco. A separate stakeholder meeting for the construction sector 
was held in Atlanta.
    OSHA initiated Small Business Regulatory Enforcement Fairness Act 
(SBREFA) proceedings in 2003, seeking the advice of small business 
representatives on the proposed rule (68 FR 30583, 30584 (5/27/03)). 
The SBREFA panel, including representatives from OSHA, the Small 
Business Administration's Office of Advocacy, and the Office of 
Management and Budget (OMB), was

[[Page 16296]]

convened on October 20, 2003. The panel conferred with small entity 
representatives (SERs) from general industry, maritime, and 
construction on November 10 and 12, 2003, and delivered its final 
report, which included comments from the SERs and recommendations to 
OSHA for the proposed rule, to OSHA's Assistant Secretary on December 
19, 2003 (Document ID 0937).
    In 2003, OSHA examined enforcement data for the years 1997 to 2002 
and identified high rates of noncompliance with the OSHA respirable 
crystalline silica PELs, particularly in construction. This period 
covers the first five years of the SEP. These enforcement data, 
presented in Table III-1, indicate that 24 percent of silica samples 
from the construction industry and 13 percent from general industry 
were at least three times the then-existing OSHA PELs. The data 
indicate that 66 percent of the silica samples obtained during 
inspections in general industry were in compliance with the PEL, while 
only 58 percent of the samples collected in construction were in 
compliance.
[GRAPHIC] [TIFF OMITTED] TR25MR16.001

    In an effort to expand the 1996 SEP, on January 24, 2008, OSHA 
implemented a National Emphasis Program (NEP) to identify and reduce or 
eliminate the health hazards associated with occupational exposure to 
crystalline silica (CPL-03-007 (1/24/08)). The NEP targeted worksites 
with elevated exposures to crystalline silica and included new program 
evaluation procedures designed to ensure that the goals of the NEP were 
measured as accurately as possible, detailed procedures for conducting 
inspections, updated information for selecting sites for inspection, 
development of outreach programs by each Regional and Area Office 
emphasizing the formation of voluntary partnerships to share 
information, and guidance on calculating PELs in construction and 
shipyards. In each OSHA Region, at least two percent of inspections 
every year are silica-related inspections. Additionally, the silica-
related inspections are conducted at a range of facilities reasonably 
representing the distribution of general industry and construction work 
sites in that region.
    A more recent analysis of OSHA enforcement data from January 2003 
to December 2009 (covering the period of continued implementation of 
the SEP and the first two years of the NEP) shows that considerable 
noncompliance with the then-existing PELs continued to occur. These 
enforcement data, presented in Table III-2, indicate that 14 percent of 
silica samples from the construction industry and 19 percent for 
general industry were at least three times the OSHA PEL during this 
period. The data indicate that 70 percent of the silica samples 
obtained during inspections in general industry were in compliance with 
the PEL, and 75 percent of the samples collected in construction were 
in compliance.

[[Page 16297]]

[GRAPHIC] [TIFF OMITTED] TR25MR16.002

    Both industry and worker groups have recognized that a 
comprehensive standard is needed to protect workers exposed to 
respirable crystalline silica. For example, ASTM International 
(originally known as the American Society for Testing and Materials) 
has published voluntary consensus standards for addressing the hazards 
of crystalline silica, and the Building and Construction Trades 
Department, AFL-CIO also has recommended a comprehensive program 
standard. These recommended standards include provisions for methods of 
compliance, exposure monitoring, training, and medical surveillance. 
The National Industrial Sand Association has also developed an 
occupational exposure program for crystalline silica that addresses 
exposure assessment and medical surveillance.
    Throughout the crystalline silica rulemaking process, OSHA has 
presented information to, and consulted with, ACCSH and the Maritime 
Advisory Committee on Occupational Safety and Health. In December of 
2009, OSHA representatives met with ACCSH to discuss the rulemaking and 
receive their comments and recommendations. On December 11, 2009, ACCSH 
passed motions supporting the concept of Table 1 in the draft proposed 
construction rule, recognizing that the controls listed in Table 1 are 
effective. As discussed with regard to paragraph (f) of the proposed 
standard for construction (paragraph (c) of the final standard for 
construction), Table 1 presents specified control measures for selected 
construction tasks. ACCSH also recommended that OSHA maintain the 
protective clothing provision found in the SBREFA panel draft 
regulatory text and restore the ``competent person'' requirement and 
responsibilities to the proposed rule. Additionally, the group 
recommended that OSHA move forward expeditiously with the rulemaking 
process.
    In January 2010, OSHA completed a peer review of the draft Health 
Effects Analysis and Preliminary Quantitative Risk Assessment following 
procedures set forth by OMB in the Final Information Quality Bulletin 
for Peer Review, published on the OMB Web site on December 16, 2004 
(see 70 FR 2664 (1/14/05)). Each peer reviewer submitted a written 
report to OSHA. The Agency revised its draft documents as appropriate 
and made the revised documents available to the public as part of its 
Notice of Proposed Rulemaking (NPRM). OSHA also made the written charge 
to the peer reviewers, the peer reviewers' names, the peer reviewers' 
reports, and the Agency's response to the peer reviewers' reports 
publicly available with publication of the proposed rule (Document ID 
1711; 1716). Five of the seven original peer reviewers submitted post-
hearing reports, commenting on OSHA's disposition of their original 
peer review comments in the proposed rule, as well as commenting on 
written and oral testimony presented at the silica hearing (Document ID 
3574).
    On August 23, 2013, OSHA posted its NPRM for respirable crystalline 
silica on its Web site and requested comments on the proposed rule. On 
September 12, 2013, OSHA published the NPRM in the Federal Register (78 
FR 56273 (9/12/13)). In the NPRM, the Agency made a preliminary 
determination that employees exposed to respirable crystalline silica 
at the current PELs face a significant risk to their health and that 
promulgating the proposed standards would substantially reduce that 
risk. The NPRM required commenters to submit their comments by December 
11, 2013. In response to stakeholder requests, OSHA extended the 
comment period until January 27, 2014 (78 FR 65242 (10/31/13)). On 
January 14, 2014, OSHA held a web chat to provide small businesses and 
other stakeholders an additional opportunity to obtain information from 
the Agency about the proposed rule. Subsequently, OSHA further extended 
the comment period to February 11, 2014 (79 FR 4641 (1/29/14)).
    As part of the instructions for submitting comments, OSHA requested 
(but did not require) that parties submitting technical or scientific 
studies or research results and those submitting comments or testimony 
on the Agency's analyses disclose the nature of financial relationships 
with (e.g., consulting agreement), and extent of review by, parties 
interested in or

[[Page 16298]]

affected by the rulemaking (78 FR 56274). Parties submitting studies or 
research results were also asked to disclose sources of funding and 
sponsorship for their research. OSHA intended for the disclosure of 
such information to promote the transparency and scientific integrity 
of evidence submitted to the record and stated that the request was 
consistent with Executive Order 13563.
    The Agency received several comments related to this request. For 
example, an industrial hygiene engineer supported the disclosure of 
potential conflict of interest information (Document ID 2278, p. 5). 
Other commenters, such as congressional representatives and industry 
associations, opposed the request, asserting that it could lead to 
prejudgment or questioning of integrity, in addition to dissuading 
participation in the rulemaking; some also questioned the legality of 
such a request or OSHA's interpretation of Executive Order 13563 (e.g., 
Document ID 1811, p. 2; 2101, pp. 2-3). A number of stakeholders from 
academia and industry submitted information related to the request for 
funding, sponsorships, and review by interested parties (e.g., Document 
ID 1766, p. 1; 2004, p. 2; 2211, p. 2; 2195, p. 17). OSHA emphasizes 
that it reviewed and considered all evidence submitted to the record.
    An informal public hearing on the proposed standards was held in 
Washington, DC from March 18 through April 4, 2014. Administrative Law 
Judges Daniel F. Solomon and Stephen L. Purcell presided over the 
hearing. The Agency heard testimony from over 200 stakeholders 
representing more than 70 organizations, such as public health groups, 
trade associations, and labor unions. Chief Administrative Law Judge 
Stephen L. Purcell closed the public hearing on April 4, 2014, allowing 
45 days--until May 19, 2014--for participants who filed a notice of 
intention to appear at the hearings to submit additional evidence and 
data, and an additional 45 days--until July 3, 2014--to submit final 
briefs, arguments, and summations (Document ID 3589, Tr. 4415-4416). 
After the hearing concluded, OSHA extended the deadline to give those 
participants who filed a notice of intention to appear at the hearings 
until June 3, 2014 to submit additional information and data to the 
record, and until July 18, 2014 to submit final briefs and arguments 
(Document ID 3569). Based upon requests from stakeholders, the second 
deadline was extended, and parties who filed a notice of intention to 
appear at the hearing were given until August 18, 2014, to submit their 
final briefs and arguments (Document ID 4192).
    OSHA provided the public with multiple opportunities to participate 
in the rulemaking process, including stakeholder meetings, the SBREFA 
panel, two comment periods (pre- and post-hearing), and a 14-day public 
hearing. Commenters were provided more than five months to comment on 
the rule before the hearing, and nearly as long to submit additional 
information, final briefs, and arguments after the hearing. OSHA 
received more than 2,000 comments on the silica NPRM during the entire 
pre-and post-hearing public participation period. In OSHA's view, 
therefore, the public was given sufficient opportunities and ample time 
to fully participate in this rulemaking.
    The final rule on occupational exposure to respirable crystalline 
silica is based on consideration of the entire record of this 
rulemaking proceeding, including materials discussed or relied upon in 
the proposal, the record of the hearing, and all written comments and 
exhibits timely received. Thus, in promulgating this final rule, OSHA 
considered all comments in the record, including those that suggested 
that OSHA withdraw its proposal and merely enforce the existing silica 
standards, as well as those that argued the proposed rule was not 
protective enough. Based on this comprehensive record, OSHA concludes 
that employees exposed to respirable crystalline silica are at 
significant risk of developing silicosis and other non-malignant 
respiratory disease, lung cancer, kidney effects, and immune system 
effects. The Agency concludes that the PEL of 50 [mu]g/m\3\ reduces the 
significant risks of material impairments of health posed to workers by 
occupational exposure to respirable crystalline silica to the maximum 
extent that is technologically and economically feasible. OSHA's 
substantive determinations with regard to the comments, testimony, and 
other information in the record, the legal standards governing the 
decision-making process, and the Agency's analysis of the data 
resulting in its assessments of risks, benefits, technological and 
economic feasibility, and compliance costs are discussed elsewhere in 
this preamble.

IV. Chemical Properties and Industrial Uses

    Silica is a compound composed of the elements silicon and oxygen 
(chemical formula SiO2). Silica has a molecular weight of 
60.08, and exists in crystalline and amorphous states, both in the 
natural environment and as produced during manufacturing or other 
processes. These substances are odorless solids, have no vapor 
pressure, and create non-explosive dusts when particles are suspended 
in air (Document ID 3637, pp. 1-3).
    Silica is classified as part of the ``silicate'' class of minerals, 
which includes compounds that are composed of silicon and oxygen and 
which may also be bonded to metal ions or their oxides. The basic 
structural units of silicates are silicon tetrahedrons 
(SiO4), pyramidal structures with four triangular sides 
where a silicon atom is located in the center of the structure and an 
oxygen atom is located at each of the four corners. When silica 
tetrahedrons bond exclusively with other silica tetrahedrons, each 
oxygen atom is bonded to the silicon atom of its original ion, as well 
as to the silicon atom from another silica ion. This results in a ratio 
of one atom of silicon to two atoms of oxygen, expressed as 
SiO2. The silicon-oxygen bonds within the tetrahedrons use 
only one-half of each oxygen's total bonding energy. This leaves 
negatively charged oxygen ions available to bond with available 
positively charged ions. When they bond with metal and metal oxides, 
commonly of iron, magnesium, aluminum, sodium, potassium, and calcium, 
they form the silicate minerals commonly found in nature (Document ID 
1334, p. 7).
    In crystalline silica, the silicon and oxygen atoms are arranged in 
a three-dimensional repeating pattern. Silica is said to be 
polymorphic, as different forms are created when the silica 
tetrahedrons combine in different crystalline structures. The primary 
forms of crystalline silica are quartz, cristobalite, and tridymite. In 
an amorphous state, silicon and oxygen atoms are present in the same 
proportions but are not organized in a repeating pattern. Amorphous 
silica includes natural and manufactured glasses (vitreous and fused 
silica, quartz glass), biogenic silica, and opals, which are amorphous 
silica hydrates (Document ID 2258, Attachment 8, pp. 45-50).
    Quartz is the most common form of crystalline silica and accounts 
for almost 12% by volume of the earth's crust. Alpha quartz, the quartz 
form that is stable below 573 [deg]C, is the most prevalent form of 
crystalline silica found in the workplace. It accounts for the 
overwhelming majority of naturally found silica and is present in 
varying amounts in almost every type of mineral. Alpha quartz is found 
in igneous, sedimentary, and metamorphic rock, and all soils contain at 
least a trace amount of quartz (Document ID 1334, p.

[[Page 16299]]

9). Alpha quartz is used in many products throughout various industries 
and is a common component of building materials (Document ID 1334, pp. 
11-15). Common trade names for commercially available quartz include: 
CSQZ, DQ 12, Min-U-Sil, Sil-Co-Sil, Snowit, Sykron F300, and Sykron 
F600 (Document ID 2258, Attachment 8, p. 43).
    Cristobalite is a form of crystalline silica that is formed at high 
temperatures (>1470 [deg]C). Although naturally occurring cristobalite 
is relatively rare, volcanic eruptions, such as Mount St. Helens, can 
release cristobalite dust into the air. Cristobalite can also be 
created during some processes conducted in the workplace. For example, 
flux-calcined diatomaceous earth is a material used as a filtering aid 
and as a filler in other products (Document ID 2258, Attachment 8, p. 
44). It is produced when diatomaceous earth (diatomite), a geological 
product of decayed unicellular organisms called diatoms, is heated with 
flux. The finished product can contain between 40 and 60 percent 
cristobalite. Also, high temperature furnaces are often lined with 
bricks that contain quartz. When subjected to prolonged high 
temperatures, this quartz can convert to cristobalite.
    Tridymite is another material formed at high temperatures (>870 
[deg]C) that is associated with volcanic activity. The creation of 
tridymite requires the presence of a flux such as sodium oxide. 
Tridymite is rarely found in nature and rarely reported in the 
workplace (Document ID 1424 pp. 5, 14).
    When heated or cooled sufficiently, crystalline silica can 
transition between the polymorphic forms, with specific transitions 
occurring at different temperatures. At higher temperatures the 
linkages between the silica tetrahedrons break and reform, resulting in 
new crystalline structures. Quartz converts to cristobalite at 1470 
[deg]C, and at 1723 [deg]C cristobalite loses its crystalline structure 
and becomes amorphous fused silica. These high temperature transitions 
reverse themselves at extremely slow rates, with different forms co-
existing for a long time after the crystal cools (Document ID 2258, 
Attachment 8, p. 47).
    Other types of transitions occur at lower temperatures when the 
silica-oxygen bonds in the silica tetrahedron rotate or stretch, 
resulting in a new crystalline structure. These low-temperature, or 
alpha to beta, transitions are readily and rapidly reversed as the 
crystal cools. At temperatures encountered by workers, only the alpha 
form of crystalline silica exists (Document ID 2258, Attachment 8, pp. 
46-48).
    Crystalline silica minerals produce distinct X-ray diffraction 
patterns, specific to their crystalline structure. The patterns can be 
used to distinguish the crystalline polymorphs from each other and from 
amorphous silica (Document ID 2258, Attachment 8, p. 45).
    The specific gravity and melting point of silica vary between 
polymorphs. Silica is insoluble in water at 20 [deg]C and in most 
acids, but its solubility increases with higher temperatures and pH, 
and it dissolves readily in hydrofluoric acid. Solubility is also 
affected by the presence of trace metals and by particle size. Under 
humid conditions water vapor in the air reacts with the surface of 
silica particles to form an external layer of silinols (SiOH). When 
these silinols are present the crystalline silica becomes more 
hydrophilic. Heating or acid washing reduces the amount of silinols on 
the surface area of crystalline silica particles. There is an external 
amorphous layer found in aged quartz, called the Beilby layer, which is 
not found on freshly cut quartz. This amorphous layer is more water 
soluble than the underlying crystalline core. Etching with hydrofluoric 
acid removes the Beilby layer as well as the principal metal impurities 
on quartz (Document ID 2258, Attachment 8, pp. 44-49).
    Crystalline silica has limited chemical reactivity. It reacts with 
alkaline aqueous solutions, but does not readily react with most acids, 
with the exception of hydrofluoric acid. In contrast, amorphous silica 
and most silicates react with most mineral acids and alkaline 
solutions. Analytical chemists relied on this difference in acid 
reactivity to develop the silica point count analytical method that was 
widely used prior to the current X-ray diffraction and infrared methods 
(Document ID 2258, Attachment 8, pp. 48-51; 1355, p. 994).
    Crystalline silica is used in industry in a wide variety of 
applications. Sand and gravel are used in road building and concrete 
construction. Sand with greater than 98% silica is used in the 
manufacture of glass and ceramics. Silica sand is used to form molds 
for metal castings in foundries, and in abrasive blasting operations. 
Silica is also used as a filler in plastics, rubber, and paint, and as 
an abrasive in soaps and scouring cleansers. Silica sand is used to 
filter impurities from municipal water and sewage treatment plants, and 
in hydraulic fracturing for oil and gas recovery (Document ID 1334, p. 
11). Silica is also used to manufacture artificial stone products used 
as bathroom and kitchen countertops, and the silica content in those 
products can exceed 85 percent (Document ID 1477, pp. 3 and 11; 2178, 
Attachment 5, p. 420).
    There are over 30 major industries and operations where exposures 
to crystalline silica can occur. They include such diverse workplaces 
as foundries, dental laboratories, concrete products and paint and 
coating manufacture, as well as construction activities including 
masonry cutting, drilling, grinding and tuckpointing, and use of heavy 
equipment during demolition activities involving silica-containing 
materials. A more detailed discussion of the industries affected by the 
proposed standard is presented in Section VII, Summary of the Final 
Economic Analysis and Final Regulatory Flexibility Analysis. 
Crystalline silica exposures can also occur in mining (which is under 
the jurisdiction of the Mine Safety and Health Administration), and in 
agriculture during plowing and harvesting.

V. Health Effects

A. Introduction

    As discussed more thoroughly in Section II of this preamble, 
Pertinent Legal Authority, section 6(b)(5) of the Occupational Safety 
and Health Act (OSH Act or Act) requires the Secretary of Labor, in 
promulgating standards dealing with toxic materials or harmful physical 
agents, to ``set the standard which most adequately assures, to the 
extent feasible, on the basis of the best available evidence, that no 
employee will suffer material impairment of health or functional 
capacity even if such employee has regular exposure to the hazard dealt 
with by such standard for the period of his working life'' (29 U.S.C. 
655). Thus, in order to set a new health standard, the Secretary must 
determine that there is a significant risk of material impairment of 
health at the existing PEL and that issuance of a new standard will 
significantly reduce or eliminate that risk.
    The Secretary's significant risk and material impairment 
determinations must be made ``on the basis of the best available 
evidence'' (29 U.S.C. 655(b)(5)). Although the Supreme Court, in its 
decision on OSHA's Benzene standard, explained that OSHA must look to 
``a body of reputable scientific thought'' in making its material harm 
and significant risk determinations, the Court added that a reviewing 
court must ``give OSHA some leeway where its findings must be made on 
the frontiers

[[Page 16300]]

of scientific knowledge'' (Indus. Union Dep't, AFL-CIO v. Am. Petroleum 
Inst., 448 U.S. 607, 656 (1980) (plurality opinion) (``Benzene'')). 
Thus, while OSHA's significant risk determination must be supported by 
substantial evidence, the Agency ``is not required to support the 
finding that a significant risk exists with anything approaching 
scientific certainty'' (Benzene, 448 U.S. at 656).
    This section provides an overview of OSHA's material harm and 
significant risk determinations: (1) Summarizing OSHA's preliminary 
methods and findings from the proposal; (2) addressing public comments 
dealing with OSHA's evaluation of the scientific literature and methods 
used to estimate quantitative risk; and (3) presenting OSHA's final 
conclusions, with consideration of the rulemaking record, on the health 
effects and quantitative risk estimates associated with worker exposure 
to respirable crystalline silica. The quantitative risk estimates and 
significance of those risks are then discussed in detail in Section VI, 
Final Quantitative Risk Assessment and Significance of Risk.

B. Summary of Health and Risk Findings

    As discussed in detail throughout this section and in Section VI, 
Final Quantitative Risk Assessment and Significance of Risk, OSHA 
finds, based upon the best available evidence in the published, peer-
reviewed scientific literature, that exposure to respirable crystalline 
silica increases the risk of silicosis, lung cancer, other non-
malignant respiratory disease (NMRD), and renal and autoimmune effects. 
In its Preliminary Quantitative Risk Assessment (QRA), OSHA used the 
best available exposure-response data from epidemiological studies to 
estimate quantitative risks. After carefully reviewing stakeholder 
comments on the Preliminary QRA and new information provided to the 
rulemaking record, OSHA finds there to be a clearly significant risk at 
the previous PELs for respirable crystalline silica (equivalent to 
approximately 100 [mu]g/m\3\ for general industry and between 250 and 
500 [mu]g/m\3\ for construction/shipyards), with excess lifetime risk 
estimates for lung cancer mortality, silicosis mortality, and NMRD 
mortality each being much greater than 1 death per 1,000 workers 
exposed for a working life of 45 years. Cumulative risk estimates for 
silicosis morbidity are also well above 1 case per 1,000 workers 
exposed at the previous PELs. At the revised PEL of 50 [mu]g/m\3\ 
respirable crystalline silica, these estimated risks are substantially 
reduced. Thus, OSHA concludes that the new PEL of 50 [mu]g/m\3\ 
provides a large reduction in the lifetime and cumulative risk posed to 
workers exposed to respirable crystalline silica.
    These findings and conclusions are consistent with those of the 
World Health Organization's International Agency for Research on Cancer 
(IARC), the U.S. Department of Health and Human Services' (HHS) 
National Toxicology Program (NTP), the National Institute for 
Occupational Safety and Health (NIOSH), and many other organizations 
and individuals, as evidenced in the rulemaking record and further 
discussed below. Many other scientific organizations and governments 
have recognized the strong body of scientific evidence pointing to the 
health risks of respirable crystalline silica and have deemed it 
necessary to take action to reduce those risks. As far back as 1974, 
NIOSH recommended that the exposure limit for crystalline silica be 
reduced to 50 [mu]g/m\3\ (Document ID 2177b, p. 2). In 2000, the 
American Conference of Governmental Industrial Hygienists (ACGIH), a 
professional society that has recommended workplace exposure limits for 
six decades, revised their Threshold Limit Value (TLV) for respirable 
crystalline silica to 50 [mu]g/m\3\ and has since further lowered its 
TLV for respirable crystalline silica to 25 [mu]g/m\3\. OSHA is setting 
its revised PEL at 50 [mu]g/m\3\ based on consideration of the body of 
evidence describing the health risks of crystalline silica as well as 
on technological feasibility considerations, as discussed in Section 
VII of this preamble and Chapter IV of the Final Economic Analysis and 
Final Regulatory Flexibility Analysis (FEA).
    To reach these conclusions, OSHA performed an extensive search and 
review of the peer-reviewed scientific literature on the health effects 
of inhalation exposure to crystalline silica, particularly silicosis, 
lung cancer, other NMRD, and renal and autoimmune effects (Document ID 
1711, pp. 7-265). Based upon this review, OSHA preliminarily determined 
that there was substantial evidence that exposure to respirable 
crystalline silica increases the risk of silicosis, lung cancer, NMRD, 
and renal and autoimmune effects (Document ID 1711, pp. 164, 181-208, 
229). OSHA also found there to be suitable exposure-response data from 
many well-conducted epidemiological studies that permitted the Agency 
to estimate quantitative risks for lung cancer mortality, silicosis and 
NMRD mortality, renal disease mortality, and silicosis morbidity 
(Document ID 1711, p. 266).
    As part of the preliminary quantitative risk assessment, OSHA 
calculated estimates of the risk of silica-related diseases assuming 
exposure over a working life (45 years) to 25, 50, 100, 250, and 500 
[mu]g/m\3\ respirable crystalline silica (corresponding to cumulative 
exposures over 45 years to 1.125, 2.25, 4.5, 11.25, and 22.5 mg/m\3\-
yrs) (see Bldg & Constr. Trades Dep't v. Brock, 838 F.2d 1258, 1264-65 
(D.C. Cir. 1988) approving OSHA's policy of using 45 years for the 
working life of an employee in setting a toxic substance standard). To 
estimate lifetime excess mortality risks at these exposure levels, OSHA 
used, for each key study, the exposure-response risk model(s) and 
regression coefficient from the model(s) in a life table analysis that 
accounted for competing causes of death due to background causes and 
cumulated risk through age 85 (Document ID 1711, pp. 360-378). For 
these analyses, OSHA used lung cancer, NMRD, or renal disease mortality 
and all-cause mortality rates to account for background risks and 
competing risks (U.S. 2006 data for lung cancer and NMRD mortality in 
all males, 1998 data for renal disease mortality, obtained from cause-
specific death rate tables published by the National Center for Health 
Statistics (2009, Document ID 1104)). The mortality risk estimates were 
presented in terms of lifetime excess risk per 1,000 workers for 
exposure over an 8-hour working day, 250 days per year, and a 45-year 
working lifetime. For silicosis morbidity, OSHA based its risk 
estimates on the cumulative risk model(s) used in each study to develop 
quantitative exposure-response relationships. These models 
characterized the risk of developing silicosis, as detected by chest 
radiography, up to the time that cohort members, including both active 
and retired workers, were last examined (78 FR 56273, 56312 (9/12/13)).
    OSHA then combined its review of the health effects literature and 
preliminary quantitative risk assessment into a draft document, 
entitled ``Occupational Exposure to Respirable Crystalline Silica--
Review of Health Effects Literature and Preliminary Quantitative Risk 
Assessment,'' and submitted it to a panel of scientific experts \2\ for 
independent peer review,

[[Page 16301]]

in accordance with the Office of Management and Budget's (OMB) ``Final 
Information Quality Bulletin for Peer Review'' (Document ID 1336). The 
peer reviewers reviewed OSHA's draft Review of Health Effects 
Literature and Preliminary QRA. The peer-review panel responded to 
nearly 20 charge questions from OSHA and commented on various aspects 
of OSHA's analysis (Document ID 1716).
---------------------------------------------------------------------------

    \2\ OSHA's contractor, Eastern Research Group, Inc. (ERG), 
conducted a search for nationally recognized experts in occupational 
epidemiology, biostatistics and risk assessment, animal and cellular 
toxicology, and occupational medicine who had no actual or apparent 
conflict of interest. ERG chose seven of the applicants to be peer 
reviewers based on their qualifications and the necessity of 
ensuring a broad and diverse panel in terms of scientific and 
technical expertise (see Document ID 1711, pp. 379-381). The seven 
peer reviewers were: Bruce Allen, Bruce Allen Consulting; Kenneth 
Crump, Ph.D., Louisiana Tech University Foundation; Murray 
Finkelstein, MD, Ph.D., McMaster University, Ontario; Gary Ginsberg, 
Ph.D., Connecticut Department of Public Health; Brian Miller, Ph.D., 
Institute of Occupational Medicine (IOM) Consulting Ltd., Scotland; 
Andrew Salmon, Ph.D., private consultant; and Noah Seixas, Ph.D., 
University of Washington, Seattle (Document ID 1711, p. 380).
---------------------------------------------------------------------------

    Overall, the peer reviewers found that OSHA was very thorough in 
its review of the literature and was reasonable in its interpretation 
of the studies with regards to the various endpoints examined, such 
that the Agency's conclusions on health effects were generally well 
founded (Document ID 1711, p. 381). The reviewers had various comments 
on OSHA's draft Preliminary QRA (Document ID 1716, pp. 107-218). OSHA 
provided a response to each comment in the Review of Health Effects 
Literature and Preliminary QRA and, where appropriate, made revisions 
(Document ID 1711, pp. 381-399). The Agency then placed the Review of 
Health Effects Literature and Preliminary QRA into the rulemaking 
docket as a background document (Document ID 1711). With the 
publication of the Notice of Proposed Rulemaking (78 FR 56723 on 9/12/
13), all aspects of the Review of Health Effects Literature and 
Preliminary QRA were open for public comment.
    Following the publication of the proposed rule (78 FR 56273 (9/12/
13)) and accompanying revised Review of Health Effects Literature and 
Preliminary QRA (Document ID 1711), the peer reviewers were invited to 
review the revised analysis, examine the written comments in the 
docket, and attend the public hearing to listen to oral testimony as it 
applied to the health effects and quantitative risk assessment. Five 
peer reviewers were available and attended. In their final comments, 
provided to OSHA following the hearings, all five peer reviewers 
indicated that OSHA had adequately addressed their original comments 
(Document ID 3574). The peer reviewers also offered additional comments 
on concerns raised during the hearing. Many of the reviewers commented 
on the difficulty of evaluating exposure-response thresholds, and 
responded to public comments regarding causation and other specific 
issues (Document ID 3574). OSHA has incorporated many of the peer 
reviewers' additional comments into its risk assessment discussion in 
the preamble. Thus, OSHA believes that the external, independent peer-
review process supports and lends legitimacy to its risk assessment 
methods and findings.
    OSHA also received substantial public comment and testimony from a 
wide variety of stakeholders supporting its Review of Health Effects 
Literature and Preliminary QRA. In general, supportive comments and 
testimony were received from NIOSH (Document ID 2177; 3998; 4233), the 
public health and medical community, labor unions, affected workers, 
private citizens, and others.
    Regarding health effects, NIOSH commented that the adverse health 
effects of exposure to respirable crystalline silica are ``well-known, 
long lasting, and preventable'' (Document ID 2177b, p. 2). Darius 
Sivin, Ph.D., of the UAW, commented, ``[o]ccupational exposure to 
silica has been recognized for centuries as a serious workplace 
hazard'' (Document ID 2282, Attachment 3, p. 4). Similarly, David 
Goldsmith, Ph.D., testified:

    There have been literally thousands of research studies on 
exposure to crystalline silica in the past 30 years. Almost every 
study tells the occupational research community that workers need 
better protection to prevent severe chronic respiratory diseases, 
including lung cancer and other diseases in the future. What OSHA is 
proposing to do in revising the workplace standard for silica seems 
to be a rational response to the accumulation of published evidence 
(Document ID 3577, Tr. 865-866).

    Franklin Mirer, Ph.D., CIH, Professor of Environmental and 
Occupational Health at CUNY School of Public Health, on behalf of the 
American Federation of Labor and Congress of Industrial Organizations 
(AFL-CIO), reiterated that silica ``is a clear and present danger to 
workers health at exposure levels prevailing now in a large number of 
industries. Workers are at significant risk for mortality and illnesses 
including lung cancer and non-malignant respiratory disease including 
COPD, and silicosis'' (Document ID 2256, Attachment 3, p. 3). The AFL-
CIO also noted that there is ``overwhelming evidence in the record that 
exposure to respirable crystalline silica poses a significant health 
risk to workers'' (Document ID 4204, p. 11). The Building and 
Construction Trades Department, AFL-CIO, further commented that the 
rulemaking record ``clearly supports OSHA's risk determination'' 
(Document ID 4223, p. 2). Likewise, the Sorptive Minerals Institute, a 
national trade association, commented, ``It is beyond dispute that OSHA 
has correctly determined that industrial exposure to certain types of 
silica can cause extremely serious, sometimes even fatal disease. In 
the massive rulemaking docket being compiled by the Agency, credible 
claims to the contrary are sparse to non-existent'' (Document ID 4230, 
p. 8). OSHA also received numerous comments supportive of the revised 
standard from affected workers and citizens (e.g., Document ID 1724, 
1726, 1731, 1752, 1756, 1759, 1762, 1764, 1787, 1798, 1800, 1802).
    Regarding OSHA's literature review for its quantitative risk 
assessment, the American Public Health Association (APHA) and the 
National Consumers League (NCL) commented, ``OSHA has thoroughly 
reviewed and evaluated the peer-reviewed literature on the health 
effects associated with exposure to respirable crystalline silica. 
OSHA's quantitative risk assessment is sound. The agency has relied on 
the best available evidence and acted appropriately in giving greater 
weight to those studies with the most robust designs and statistical 
analyses'' (Document ID 2178, Attachment 1, p. 1; 2373, p. 1).
    Dr. Mirer, who has served on several National Academy of Sciences 
committees setting risk assessment guidelines, further commented that 
OSHA's risk analysis is ``scientifically correct, and consistent with 
the latest thinking on risk assessment,'' (Document ID 2256, Attachment 
3, p. 3), citing the National Academies' National Research Council's 
Science and Decisions: Advancing Risk Assessment (Document ID 4052), 
which makes technical recommendations on risk assessment and risk-based 
decision making (Document ID 3578, Tr. 935-936). In post-hearing 
comments expanding on this testimony, the AFL-CIO also noted that 
OSHA's risk assessment methodologies are transparent and consistent 
with practices recommended by the National Research Council in its 
publication, Risk Assessment in the Federal Government: Managing the 
Process, and with the Environmental Protection Agency's Guidelines for 
Carcinogenic Risk Assessment (Document ID 4204, p. 20). Similarly, Kyle 
Steenland, Ph.D., Professor in the Department of Environmental Health 
at Rollins School of Public Health, Emory University, one of the 
researchers on whose studies OSHA relied, testified that ``OSHA has

[[Page 16302]]

done a very capable job in conducting the summary of the literature and 
doing its own risk assessment'' (Document ID 3580, Tr. 1235). 
Collectively, these comments and testimony support OSHA's use of the 
best available evidence and methods to estimate quantitative risks of 
lung cancer mortality, silicosis and NMRD mortality, renal disease 
mortality, and silicosis morbidity from exposure to respirable 
crystalline silica.
     Based on OSHA's Preliminary QRA, many commenters recognized that 
reducing the permissible exposure limit is necessary to reduce 
significant risks presented by exposure to respirable crystalline 
silica (Document ID 4204, pp. 11-12; 2080, p. 1; 2339, p. 2). For 
example, the AFL-CIO stated that ``OSHA based its proposal on more than 
adequate evidence, but more recent publications have described further 
the risk posed by silica exposure, and further justify the need for new 
silica standards'' (Document ID 4204, pp. 11-12). Similarly, the 
American Society of Safety Engineers (ASSE) remarked that ``[w]hile 
some may debate the science underlying the findings set forth in the 
proposed rule, overexposure to crystalline silica has been linked to 
occupational illness since the time of the ancient Greeks, and 
reduction of the current permissible exposure limit (PEL) to that 
recommended for years by the National Institute for Occupational Safety 
and Health (NIOSH) is long overdue'' (Document ID 2339, p. 2).
    Not every commenter agreed, however, as OSHA also received critical 
comments and testimony from various employers and their 
representatives, as well as some organizations representing affected 
industries. In general, these comments were critical of the underlying 
studies on which OSHA relied for its quantitative risk assessment, or 
with the methods used by OSHA to estimate quantitative risks. Some 
commenters also presented additional studies for OSHA to consider. OSHA 
thoroughly reviewed these and did not find them adequate to alter 
OSHA's overall conclusions of health risk, as discussed in great detail 
in the sections that follow.
    After considering the evidence and testimony in the record, as 
discussed below, OSHA affirms its approach to quantify health risks 
related to exposure to respirable crystalline silica and the Agency's 
preliminary conclusions. In the final risk assessment that is now 
presented as part of this final rule in Section VI, Final Quantitative 
Risk Assessment and Significance of Risk, OSHA concludes that there is 
a clearly significant risk at the previous PELs for respirable 
crystalline silica, with excess lifetime risk estimates for lung cancer 
mortality, silicosis mortality, and NMRD mortality each being much 
greater than 1 death per 1,000 workers as a result of exposure for 45 
working years (see Section VI, Final Quantitative Risk Assessment and 
Significance of Risk). At the revised PEL of 50 [micro]g/m\3\ 
respirable crystalline silica, OSHA finds the estimated risks to be 
substantially reduced. Cumulative risk estimates for silicosis 
morbidity are also well above 1 case per 1,000 workers at the previous 
PELs, with a substantial reduction at the revised PEL (see Section VI, 
Final Quantitative Risk Assessment and Significance of Risk, Table VI-
1).
    The health effects associated with silica exposure are well-
established and supported by the record. Based on the record evidence, 
OSHA concludes that exposure to respirable crystalline silica causes 
silicosis and is the only known cause of silicosis. This causal 
relationship has long been accepted in the scientific and medical 
communities. In fact, the Department of Labor produced a video in 1938 
featuring then Secretary of Labor Frances Perkins discussing the 
occurrence of silicosis among workers exposed to silica (see https://www.osha.gov/silica/index.html). Silicosis is a progressive disease 
induced by the inflammatory effects of respirable crystalline silica in 
the lung, which leads to lung damage and scarring and, in some cases, 
progresses to complications resulting in disability and death (see 
Section VI, Final Quantitative Risk Assessment and Significance of 
Risk). OSHA used a weight-of-evidence approach to evaluate the 
scientific studies in the literature to determine their overall quality 
and whether there is substantial evidence that exposure to respirable 
crystalline silica increases the risk of a particular health effect.
    For lung cancer, OSHA reviewed the published, peer-reviewed 
scientific literature, including 60 epidemiological studies covering 
more than 30 occupational groups in over a dozen industrial sectors 
(see Document ID 1711, pp. 77-170). Based on this comprehensive review, 
and after considering the rulemaking record as a whole, OSHA concludes 
that the data provide ample evidence that exposure to respirable 
crystalline silica increases the risk of lung cancer among workers (see 
Document ID 1711, p. 164). OSHA's conclusion is consistent with that of 
IARC, which is the specialized cancer agency that is part of the World 
Health Organization and utilizes interdisciplinary (e.g., 
biostatistics, epidemiology, and laboratory sciences) experts to 
comprehensively identify the causes of cancer. In 1997, IARC classified 
respirable crystalline silica dust, in the form of quartz or 
cristobalite, as Group 1, i.e., ``carcinogenic to humans,'' following a 
thorough expert committee review of the peer-reviewed scientific 
literature (Document ID 2258, Attachment 8, p. 211). OSHA notes that 
IARC classifications and accompanying monographs are well recognized in 
the scientific community, having been described as ``the most 
comprehensive and respected collection of systematically evaluated 
agents in the field of cancer epidemiology'' (Demetriou et al., 2012, 
Document ID 4131, p. 1273). For silica, IARC's overall finding was 
based on studies of nine occupational cohorts that it considered to be 
the least influenced by confounding factors (see Document ID 1711, p. 
76). OSHA included these studies in its review, in addition to several 
other studies (Document ID 1711, pp. 77-170).
    Since IARC's 1997 determination that respirable crystalline silica 
is a Group 1 carcinogen, the scientific community has reaffirmed the 
soundness of this finding. In March of 2009, 27 scientists from eight 
countries participated in an additional IARC review of the scientific 
literature and reaffirmed that respirable crystalline silica dust is a 
Group 1 human carcinogen (Document ID 1473, p. 396). Additionally, in 
2000, the NTP, which is a widely-respected interagency program under 
HHS that evaluates chemicals for possible toxic effects on public 
health, also concluded that respirable crystalline silica is a known 
human carcinogen (Document ID 1164, p. 1).
    For NMRD other than silicosis, based on its review of several 
studies and all subsequent record evidence, OSHA concludes that 
exposure to respirable crystalline silica increases the risk of 
emphysema, chronic bronchitis, and pulmonary function impairment (see 
Section VI, Final Quantitative Risk Assessment and Significance of 
Risk; Document ID 1711, pp. 181-208). For renal disease, OSHA reviewed 
the epidemiological literature and finds that a number of 
epidemiological studies reported statistically significant associations 
between occupational exposure to silica dust and chronic renal disease, 
subclinical renal changes, end-stage renal disease morbidity, chronic 
renal disease mortality, and granulomatosis with polyangitis (see 
Section VI, Final Quantitative Risk Assessment and Significance of 
Risk; Document ID 1711, p. 228). For autoimmune effects, OSHA reviewed

[[Page 16303]]

epidemiological information in the record suggesting an association 
between respirable crystalline silica exposure and increased risk of 
systemic autoimmune diseases, including scleroderma, rheumatoid 
arthritis, and systemic lupus erythematosus (see Section VI, Final 
Quantitative Risk Assessment and Significance of Risk; Document ID 
1711, p. 229). Therefore, OSHA concludes that there is substantial 
evidence that silica exposure increases the risks of renal and of 
autoimmune disease (see Section VI, Final Quantitative Risk Assessment 
and Significance of Risk; Document ID 1711, p. 229).
    OSHA also finds there to be suitable exposure-response data from 
many well-conducted studies that permit the Agency to estimate 
quantitative risks for lung cancer mortality, silicosis and NMRD 
mortality, renal disease mortality, and silicosis morbidity (see 
Section VI, Final Quantitative Risk Assessment and Significance of 
Risk; Document ID 1711, p. 266). OSHA believes the exposure-response 
data in these studies collectively represent the best available 
evidence for use in estimating the quantitative risks related to silica 
exposure. For lung cancer mortality, OSHA relies upon a number of 
published studies that analyzed exposure-response relationships between 
respirable crystalline silica and lung cancer. These included studies 
of cohorts from several industry sectors: Diatomaceous earth workers 
(Rice et al., 2001, Document ID 1118), Vermont granite workers 
(Attfield and Costello, 2004, Document ID 0285), North American 
industrial sand workers (Hughes et al., 2001, Document ID 1060), and 
British coal miners (Miller and MacCalman, 2009, Document ID 1306). 
These studies are scientifically sound due to their sufficient size and 
adequate years of follow-up, sufficient quantitative exposure data, 
lack of serious confounding by exposure to other occupational 
carcinogens, consideration (for the most part) of potential confounding 
by smoking, and absence of any apparent selection bias (see Section VI, 
Final Quantitative Risk Assessment and Significance of Risk; Document 
ID 1711, p. 165). They all demonstrated positive, statistically 
significant exposure-response relationships between exposure to 
crystalline silica and lung cancer mortality. Also compelling was a 
pooled analysis (Steenland et al., 2001a, Document ID 0452) of 10 
occupational cohorts (with a total of 65,980 workers and 1,072 lung 
cancer deaths), which was also used as a basis for IARC's 2009 
reaffirmation of respirable crystalline silica as a human carcinogen. 
This analysis by Steenland et al. found an overall positive exposure-
response relationship between cumulative exposure to crystalline silica 
and lung cancer mortality (see Section VI, Final Quantitative Risk 
Assessment and Significance of Risk; Document ID 1711, pp. 269-292). 
Based on these studies, OSHA estimates that the lifetime lung cancer 
mortality excess risk associated with 45 years of exposure to 
respirable crystalline silica ranges from 11 to 54 deaths per 1,000 
workers at the previous general industry PEL of 100 [micro]g/m\3\ 
respirable crystalline silica, and 5 to 23 deaths per 1,000 workers at 
the revised PEL of 50 [micro]g/m\3\ respirable crystalline silica (see 
Section VI, Final Quantitative Risk Assessment and Significance of 
Risk, Table VI-1). These estimates exceed by a substantial margin the 
one in a thousand benchmark that OSHA has generally applied to its 
health standards following the Supreme Court's Benzene decision (448 
U.S. 607, 655 (1980)).
    For silicosis and NMRD mortality, OSHA relies upon two published, 
peer-reviewed studies: A pooled analysis of silicosis mortality data 
from six epidemiological studies (Mannetje et al., 2002b, Document ID 
1089), and an exposure-response analysis of NMRD mortality among 
diatomaceous earth workers (Park et al, 2002, Document ID 0405) (see 
Section VI, Final Quantitative Risk Assessment and Significance of 
Risk; Document ID 1711, p. 292). The pooled analysis had a total of 
18,634 subjects, 150 silicosis deaths, and 20 deaths from unspecified 
pneumoconiosis, and demonstrated an increasing mortality rate with 
silica exposure (Mannetje et al., 2002b, Document ID 1089; see also 
1711, pp. 292-295). To estimate the risks of silicosis mortality, OSHA 
used the model described by Mannetje et al. but used rate ratios that 
were estimated from a sensitivity analysis conducted by ToxaChemica, 
Inc. that was expected to better control for age and exposure 
measurement uncertainty (2004, Document ID 0469; 1711, p. 295). OSHA's 
estimate of lifetime silicosis mortality risk is 11 deaths per 1,000 
workers at the previous general industry PEL, and 7 deaths per 1,000 
workers at the revised PEL (see Section VI, Final Quantitative Risk 
Assessment and Significance of Risk, Table VI-1).
    The NMRD analysis by Park et al. (2002, Document 0405) included 
pneumoconiosis (including silicosis), chronic bronchitis, and 
emphysema, since silicosis is a cause of death that is often 
misclassified as emphysema or chronic bronchitis (see Document ID 1711, 
p. 295). Positive exposure-response relationships were found between 
exposure to crystalline silica and excess risk for NMRD mortality (see 
Section VI, Final Quantitative Risk Assessment and Significance of 
Risk; Document ID 1711, pp. 204-206, 295-297). OSHA's estimate of 
excess lifetime NMRD mortality risk, calculated using the results from 
Park et al., is 85 deaths per 1,000 workers at the previous general 
industry PEL of 100 [micro]g/m\3\ respirable crystalline silica, and 44 
deaths per 1,000 workers at the revised PEL (see Section VI, Final 
Quantitative Risk Assessment and Significance of Risk, Table VI-1).\3\
---------------------------------------------------------------------------

    \3\ The risk estimates for silicosis and NMRD are not directly 
comparable, as the endpoint for the NMRD analysis (Park et al., 
2002, Document ID 0405) was death from all non-cancer lung diseases, 
including silicosis, pneumoconiosis, emphysema, and chronic 
bronchitis, whereas the endpoint for the silicosis analysis 
(Mannetje et al., 2002b, Document ID 1089) was deaths coded as 
silicosis or other pneumoconiosis only (Document ID 1711, pp. 297-
298).
---------------------------------------------------------------------------

    For renal disease mortality, Steenland et al. (2002a, Document ID 
0448) conducted a pooled analysis of three cohorts (with a total of 
13,382 workers) that found a positive exposure-response relationship 
for both multiple-cause mortality (i.e., any mention of renal disease 
on the death certificate) and underlying cause mortality. OSHA used the 
Steenland et al. (2002a, Document ID 0448) pooled analysis to estimate 
risks, given its large number of workers from cohorts with sufficient 
exposure data (see Section VI, Final Quantitative Risk Assessment and 
Significance of Risk; Document ID 1711, pp. 314-315). OSHA's analysis 
for renal disease mortality shows estimated lifetime excess risk of 39 
deaths per 1,000 workers at the previous general industry PEL of 100 
[micro]g/m\3\ respirable crystalline silica, and 32 deaths per 1,000 
workers exposed at the revised PEL of 50 [micro]g/m\3\ (see Section VI, 
Final Quantitative Risk Assessment and Significance of Risk, Table VI-
1). OSHA acknowledges, however, that there are considerably less data 
for renal disease mortality, and thus the findings based on them are 
less robust than those for silicosis, lung cancer, and NMRD mortality 
(see Section VI, Final Quantitative Risk Assessment and Significance of 
Risk; Document ID 1711, p. 229). For autoimmune disease, there were no 
quantitative exposure-response data available for a quantitative risk 
assessment (see Section VI, Final Quantitative Risk Assessment and 
Significance of Risk; Document ID 1711, p. 229).

[[Page 16304]]

    For silicosis morbidity, OSHA reviewed the principal studies 
available in the scientific literature that have characterized the risk 
to exposed workers of acquiring silicosis, as detected by the 
appearance of opacities on chest radiographs (see Section VI, Final 
Quantitative Risk Assessment and Significance of Risk; Document ID 
1711, p. 357). The most reliable estimates of silicosis morbidity came 
from five studies that evaluated radiographs over time, including after 
workers left employment: The U.S. gold miner cohort studied by 
Steenland and Brown (1995b, Document ID 0451); the Scottish coal miner 
cohort studied by Buchanan et al. (2003, Document ID 0306); the Chinese 
tin mining cohort studied by Chen et al. (2001, Document ID 0332); the 
Chinese tin, tungsten, and pottery worker cohorts studied by Chen et 
al. (2005, Document ID 0985); and the South African gold miner cohort 
studied by Hnizdo and Sluis-Cremer (1993, Document ID 1052) (see 
Section VI, Final Quantitative Risk Assessment and Significance of 
Risk; Document ID 1711, pp. 316-343). These studies demonstrated 
positive exposure-response relationships between exposure to 
crystalline silica and silicosis risk. Based on the results of these 
studies, OSHA estimates a cumulative risk for silicosis morbidity of 
between 60 and 773 cases per 1,000 workers for a 45-year exposure to 
the previous general industry PEL of 100 [micro]g/m\3\ respirable 
crystalline silica depending upon the study used, and between 20 and 
170 cases per 1,000 workers exposed at the new PEL of 50 [micro]g/m\3\ 
depending upon the study used (see Section VI, Final Quantitative Risk 
Assessment and Significance of Risk, Table VI-1). Thus, like OSHA's 
risk estimates for other health endpoints, the risk is substantially 
lower, though still significant, at the revised PEL.
    In conclusion, OSHA finds, based on the best available evidence and 
methods to estimate quantitative risks of disease resulting from 
exposure to respirable crystalline silica, that there are significant 
risks of material health impairment at the former PELs for respirable 
crystalline silica, which would be substantially reduced (but not 
entirely eliminated) at the new PEL of 50 [mu]g/m\3\. In meeting its 
legal burden to estimate the health risks posed by respirable 
crystalline silica, OSHA has used the best available evidence and 
methods to estimate quantitative risks of disease resulting from 
exposure to respirable crystalline silica. As a result, the Agency 
finds that the lifetime excess mortality risks (for lung cancer, NMRD 
and silicosis, and renal disease) and cumulative risk (silicosis 
morbidity) posed to workers exposed to respirable crystalline silica 
over a working life represent significant risks that warrant 
mitigation, and that these risks will be substantially reduced at the 
revised PEL of 50 [mu]g/m\3\ respirable crystalline silica.

C. Summary of the Review of Health Effects Literature and Preliminary 
QRA

    As noted above, a wide variety of stakeholders offered comments and 
testimony in this rulemaking on issues related to health and risk. Many 
of these comments were submitted in response to OSHA's preliminary risk 
and material impairment determinations, which were presented in two 
background documents, entitled ``Occupational Exposure to Respirable 
Crystalline Silica--Review of Health Effects Literature and Preliminary 
Quantitative Risk Assessment'' (Document ID 1711) and ``Supplemental 
Literature Review of Epidemiological Studies on Lung Cancer Associated 
with Exposure to Respirable Crystalline Silica'' (Document ID 1711, 
Attachment 1), and summarized in the proposal in Section V, Health 
Effects Summary, and Section VI, Summary of OSHA's Preliminary 
Quantitative Risk Assessment.
    In this subsection, OSHA summarizes the major findings of the two 
background documents. The Agency intends for this subsection to provide 
the detailed background necessary to fully understand stakeholders' 
comments and OSHA's responses.
1. Background
    As noted above, OSHA's Review and Supplemental Review of Health 
Effects Literature and Preliminary Quantitative Risk Assessment 
(Document ID 1711; 1711, Attachment 1) were the result of the Agency's 
extensive search and review of the peer-reviewed scientific literature 
on the health effects of inhalation exposure to crystalline silica, 
particularly silicosis, lung cancer and cancer at other sites, non-
malignant respiratory diseases (NMRD) other than silicosis, and renal 
and autoimmune effects. The purposes of this detailed search and 
scientific review were to determine the nature of the hazards presented 
by exposure to respirable crystalline silica, and to evaluate whether 
there was an adequate basis, with suitable data availability, for 
quantitative risk assessment.
    Much of the scientific evidence that describes the health effects 
and risks associated with exposure to crystalline silica consisted of 
epidemiological studies of worker populations; OSHA also reviewed 
animal and in vitro studies. OSHA used a weight-of-evidence approach in 
evaluating this evidence. Under this approach, OSHA evaluated the 
relevant studies to determine their overall quality. Factors considered 
in assessing the quality of studies included: (1) The size of the 
cohort studied and the power of the study to detect a sufficiently low 
level of disease risk; (2) the duration of follow-up of the study 
population; (3) the potential for study bias (e.g., selection bias in 
case-control studies or survivor effects in cross-sectional studies); 
and (4) the adequacy of underlying exposure information for examining 
exposure-response relationships. Studies were deemed suitable for 
inclusion in OSHA's Preliminary Quantitative Risk Assessment (QRA) 
where there was adequate quantitative information on exposure and 
disease risks and the study was judged to be sufficiently high quality 
according to these criteria.
    Based upon this weight-of-evidence approach, OSHA preliminarily 
determined that there is substantial evidence in the peer-reviewed 
scientific literature that exposure to respirable crystalline silica 
increases the risk of silicosis, lung cancer, other NMRD, and renal and 
autoimmune effects. The Preliminary QRA indicated that, for silicosis 
and NMRD mortality, lung cancer mortality, and renal disease mortality, 
there is a significant risk at the previous PELs for respirable 
crystalline silica, with excess lifetime risk estimates substantially 
greater than 1 death per 1,000 workers as a result of exposure over a 
working life (45 years, from age 20 to age 65). At the revised PEL of 
50 [mu]g/m\3\ respirable crystalline silica, OSHA estimated that these 
risks would be substantially reduced. Cumulative risk estimates for 
silicosis morbidity were also well above 1 case per 1,000 workers at 
the previous PELs, with a substantial reduction at the revised PEL.
2. Summary of the Review of Health Effects Literature
    In its Review of Health Effects Literature, OSHA identified the 
adverse health effects associated with the inhalation of respirable 
crystalline silica (Document ID 1711). OSHA covered the following 
topics: Silicosis (including relevant data from U.S. disease 
surveillance efforts), lung cancer and cancer at other sites, non-
malignant respiratory diseases (NMRD) other than silicosis, renal and 
autoimmune effects, and physical factors affecting the toxicity of 
crystalline silica. Most of the evidence that described the health 
risks associated with exposure to silica

[[Page 16305]]

consisted of epidemiological studies of worker populations; animal and 
in vitro studies on mode of action and molecular toxicology were also 
described. OSHA focused solely on those studies associated with 
airborne exposure to respirable crystalline silica due to the lack of 
evidence of health hazards from dermal or oral exposure. The review was 
further confined to issues related to the inhalation of respirable 
dust, which is generally defined as particles that are capable of 
reaching the pulmonary region of the lung (i.e., particles less than 10 
microns ([mu]m) in aerodynamic diameter), in the form of either quartz 
or cristobalite, the two forms of crystalline silica most often 
encountered in the workplace.
a. Silicosis
i. Types
    Silicosis is an irreversible, progressive disease induced by the 
inflammatory effects of respirable crystalline silica in the lung, 
leading to lung damage and scarring and, in some cases, progressing to 
complications resulting in disability and death. Exposure to respirable 
crystalline silica is the only known cause of silicosis. Three types of 
silicosis have been described: An acute form following intense exposure 
to respirable dust of high crystalline silica content for a relatively 
short period (i.e., a few months or years); an accelerated form, 
resulting from about 5 to 15 years of heavy exposure to respirable 
dusts of high crystalline silica content; and, most commonly, a chronic 
form that typically follows less intense exposure of more than 20 years 
(Becklake, 1994, Document ID 0294; Balaan and Banks, 1992, 0289). In 
both the accelerated and chronic forms of the disease, lung 
inflammation leads to the formation of excess connective tissue, or 
fibrosis, in the lung. The hallmark of the chronic form of silicosis is 
the silicotic islet or nodule, one of the few agent-specific lesions in 
pathology (Balaan and Banks, 1992, Document ID 0289). As the disease 
progresses, these nodules, or fibrotic lesions, increase in density and 
can develop into large fibrotic masses, resulting in progressive 
massive fibrosis (PMF). Once established, the fibrotic process of 
chronic silicosis is thought to be irreversible (Becklake, 1994, 
Document ID 0294). There is no specific treatment for silicosis (Davis, 
1996, Document ID 0998; Banks, 2005, 0291).
    Chronic silicosis is the most frequently observed type of silicosis 
in the U.S. today. Affected workers may have a dry chronic cough, 
sputum production, shortness of breath, and reduced pulmonary function. 
These symptoms result from airway restriction and/or obstruction caused 
by the development of fibrotic scarring in the alveolar sacs and lower 
region of the lung. Prospective studies that follow the exposed cohort 
over a long period of time with periodic examinations can provide the 
best information on factors affecting the development and progression 
of silicosis, which has a latency period (the interval between 
beginning of exposure to silica and the onset of disease) from 10 to 30 
years after first exposure (Weissman and Wagner, 2005; Document ID 
0481).
ii. Diagnosis
    The scarring caused by silicosis can be detected by chest x-ray or 
computerized tomography (CT) when the lesions become large enough to 
appear as visible opacities. The clinical diagnosis of silicosis has 
three requirements: Recognition by the physician that exposure to 
crystalline silica has occurred; the presence of chest radiographic 
abnormalities consistent with silicosis; the absence of other illnesses 
that could resemble silicosis on a chest radiograph (e.g., pulmonary 
fungal infection or tuberculosis) (Balaan and Banks, 1992, Document ID 
0289; Banks, 2005, 0291). A standardized system to classify opacities 
seen in chest radiographs was developed by the International Labour 
Organization (ILO) to describe the presence and severity of silicosis 
on the basis of size, shape, and density of opacities, which together 
indicate the severity and extent of lung involvement (ILO, 1980, 
Document ID 1063; ILO, 2002, 1064; ILO, 2011, 1475; Merchant and 
Schwartz, 1998, 1096; NIOSH, 2011, 1513). The density of opacities seen 
on chest radiographs is classified on a 4-point category scale (0, 1, 
2, or 3), with each category divided into three, giving a 12-
subcategory scale between 0/0 and 3/+. For each subcategory, the top 
number indicates the major category that the profusion most closely 
resembles, and the bottom number indicates the major category that was 
given secondary consideration. Category 0 indicates the absence of 
visible opacities and categories 1 to 3 reflect increasing profusion of 
opacities and a concomitant increase in severity of disease. The bottom 
number can deviate from the top number by 1. At the extremes of the 
scale, a designation of 0/- or 3/+ may be used. Subcategory 0/- 
represents a radiograph that is obviously absent of small opacities. 
Subcategory 3/+ represents a radiograph that shows much greater 
profusion than depicted on a standard 3/3 radiograph.
    To address the low sensitivity of chest x-rays for detecting 
silicosis, Hnizdo et al. (1993, Document ID 1050) recommended that 
radiographs consistent with an ILO category of 0/1 or greater be 
considered indicative of silicosis among workers exposed to a high 
concentration of silica-containing dust. In like manner, to maintain 
high specificity, chest x-rays classified as category 1/0 or 1/1 should 
be considered as a positive diagnosis of silicosis. A biopsy is not 
necessary to make a diagnosis and a diagnosis does not require that 
chest x-ray films or digital radiographic images be rated using the ILO 
system (NIOSH, 2002, Document ID 1110).
iii. Review of Occupation-Based Epidemiological Studies
    The causal relationship between exposure to crystalline silica and 
silicosis has long been accepted in the scientific and medical 
communities. OSHA reviewed a large number of cross-sectional and 
retrospective studies conducted to estimate the quantitative 
relationship between exposure to crystalline silica and the development 
of silicosis (e.g., Kreiss and Zhen, 1996, Document ID 1080; Love et 
al., 1999, 0369; Ng and Chan, 1994, 0382; Rosenman et al., 1996, 0423; 
Churchyard et al., 2003, 1295; Churchyard et al., 2004, 0986; Hughes et 
al., 1998, 1059; Muir et al., 1989a, 1102; Muir et al., 1989b, 1101; 
Park et al., 2002, 0405; Chen et al., 2001, 0332; Chen et al., 2005, 
0985; Hnizdo and Sluis-Cremer, 1993, 1052; Miller et al., 1998, 0374; 
Buchanan et al., 2003, 0306; Steenland and Brown, 1995b, 0451). In 
general, these studies, particularly those that included retirees, 
found a risk of radiological silicosis (usually defined as x-ray films 
classified as ILO major category 1 or greater) among workers exposed 
near the range of cumulative exposures permitted by current exposure 
limits. The studies' methods and findings are presented in detail in 
the Preliminary QRA (Document ID 1711, pp. 316-340); those studies on 
which OSHA relied for its risk estimates are also discussed in the 
Summary of the Preliminary QRA, below.
    OSHA's review of the silicosis literature also focused on specific 
issues associated with the factors that affect the progression of the 
disease and the relationship between the appearance of radiological 
abnormalities indicative of silicosis and pulmonary function decline. 
From its review of the health literature, OSHA made a number of 
preliminary findings. First, the size of opacities apparent on initial 
x-ray films is a determinant of future disease

[[Page 16306]]

progression, with subjects exhibiting large opacities more likely to 
experience progression than those having smaller opacities (Hughes et 
al., 1982, Document ID 0362; Lee et al., 2001, 1086; Ogawa et al., 
2003, 0398). Second, continued exposure to respirable crystalline 
silica following diagnosis of radiological silicosis increases the 
probability of disease progression compared to those who are not 
further exposed (Hessel et al., 1988, Document ID 1042), although there 
remains a likelihood of progression even absent continued exposure 
(Hessel et al., 1988, Document ID 1042; Miller et al., 1998, 0374; 
Ogawa et al., 2003, 0398; Yang et al., 2006, 1134).
    With respect to the relationship between radiological silicosis and 
pulmonary function declines, literature findings are mixed. A number of 
studies have reported pulmonary function declines among workers 
exhibiting a degree of small-opacity profusion consistent with ILO 
categories 2 and 3 (e.g., Ng and Chan, 1992, Document ID 1107). 
However, although some studies have not found pulmonary function 
declines associated with silicosis scored as ILO category 1, a number 
of other studies have documented declines in pulmonary function in 
persons exposed to silica and whose radiograph readings are in the 
major ILO category 1 (i.e., 1/0, 1/1, 1/2), or even before changes were 
seen on chest x-ray (Cowie, 1998, 0993; Cowie and Mabena, 1991, 0342; 
Ng et al., 1987(a), 1108; Wang et al., 1997, 0478). Thus, OSHA 
preliminarily concluded that at least some individuals will develop 
pulmonary function declines absent radiological changes indicative of 
silicosis. The Agency posited that this may reflect the relatively poor 
sensitivity of x-ray films in detecting silicosis or may be due to 
pulmonary function declines related to silica-induced chronic 
obstructive pulmonary disease (see Document ID 1711, pp. 49-75).
iv. Surveillance
    Unlike most occupational diseases, surveillance statistics are 
available on silicosis mortality and morbidity in the U.S. The most 
comprehensive and current source of surveillance data in the U.S. 
related to occupational lung diseases, including silicosis, is the 
National Institute for Occupational Safety and Health (NIOSH) Work-
Related Lung Disease (WoRLD) Surveillance System (NIOSH, 2008c, 
Document ID 1308). Other sources are detailed in the Review of Health 
Effects Literature (Document ID 1711). Mortality data are compiled from 
death certificates reported to state vital statistics offices, which 
are collected by the National Center for Health Statistics (NCHS), an 
agency within the Centers for Disease Control and Prevention (e.g., 
CDC, 2005, Document ID 0319).
    Silicosis-related mortality has declined in the U.S. over the time 
period for which these data have been collected. From 1968 to 2005, the 
annual number of silicosis deaths decreased from 1,157 to 161 (NIOSH, 
2008c, Document ID 1308; http://wwwn.cdc.gov/eworld). The CDC cited two 
main factors that were likely responsible for the declining trend in 
silicosis mortality since 1968 (CDC, 2005, Document ID 0319). First, 
many deaths during the early part of the study period were among 
workers whose main exposure to respirable crystalline silica probably 
occurred before introduction of national silica standards established 
by OSHA and the Mine Safety and Health Administration (MSHA) (i.e., 
permissible exposure limits (PELs)); these standards likely led to 
reduced silica dust exposure beginning in the 1970s. Second, employment 
has declined in heavy industries (e.g., foundries) where silica 
exposure was prevalent (CDC, 2005, Document ID 0319).
    Despite this decline, silicosis deaths among workers of all ages 
result in significant premature mortality; between 1996 and 2005, a 
total of 1,746 deaths resulted in a total of 20,234 years of life lost 
from life expectancy, with an average of 11.6 years of life lost. For 
the same period, among 307 decedents who died before age 65 (the end of 
a working life), there were 3,045 years of life lost up to age 65, with 
an average of 9.9 years of life lost from a working life (NIOSH, 2008c, 
Document ID 1308).
    Surveillance data on silicosis morbidity, primarily from hospital 
discharge records, are available only from the few states that have 
administered disease surveillance programs for silicosis. For the 
reporting period 1993-2002, these states recorded 879 cases of 
silicosis (NIOSH 2008c, Document ID 1308). Nationwide hospital 
discharge data compiled by NIOSH (2008c, Document ID 1308) and the 
Council of State and Territorial Epidemiologists (CSTE, 2005, Document 
ID 0996) indicate that, for the years 1970 to 2004, there were at least 
1,000 hospitalizations that were coded for silicosis each year, except 
one.
    Relying exclusively on such passive case-based disease surveillance 
systems that depend on the health care community to generate records is 
likely to understate the prevalence of diseases associated with 
respirable crystalline silica (Froines et al., 1989, Document ID 0385). 
In order to diagnose occupational diseases, health care professionals 
must have information about occupational histories and must be able to 
recognize occupational diseases (Goldman and Peters, 1981, Document ID 
1027; Rutstein et al., 1983, 0425). The first criterion to be met in 
diagnosing silicosis is knowing a patient's history of exposure to 
crystalline silica. In addition to the lack of information about 
exposure histories, difficulty in recognizing occupational illnesses 
like silicosis, that manifest themselves long after initial exposure, 
contributes to under-recognition and underreporting by health care 
providers. Based on an analysis of data from Michigan's silicosis 
surveillance activities, Rosenman et al. (2003, Document ID 0420) 
estimated that silicosis mortality and morbidity were understated by a 
factor of between 2.5 and 5, and estimated that between 3,600 and 7,300 
new cases of silicosis likely occurred in the U.S. annually between 
1987 and 1996.
b. Lung Cancer
    i. International Agency for Research on Cancer (IARC) 
Classification
    In 1997, the IARC determined that there was sufficient evidence to 
regard crystalline silica as a human carcinogen (IARC, 1997, Document 
ID 1062). This finding was based largely on nine studies of cohorts in 
four industry sectors that IARC considered to be the least influenced 
by confounding factors (sectors included quarries and granite works, 
gold mining, ceramic/pottery/refractory brick industries, and the 
diatomaceous earth industry). NIOSH also determined that crystalline 
silica is a human carcinogen after evaluating updated literature (2002, 
Document ID 1110).
    ii. Review of Occupation-Based Epidemiological Studies
    OSHA conducted an independent review of the epidemiological 
literature on exposure to respirable crystalline silica and lung 
cancer, covering more than 30 occupational groups in over a dozen 
industrial sectors. OSHA's review included approximately 60 primary 
epidemiological studies. Based on this review, OSHA preliminarily 
concluded that the human data provides ample evidence that exposure to 
respirable crystalline silica increases the risk of lung cancer among 
workers.
    The strongest evidence for carcinogenicity came from studies in 
five industry sectors:
     Diatomaceous Earth Workers (Checkoway et al., 1993, 
Document ID 0324; Checkoway et al., 1996, 0325; Checkoway et al., 1997, 
0326;

[[Page 16307]]

Checkoway et al., 1999, 0327; Seixas et al., 1997, 0431);
     British Pottery Workers (Cherry et al., 1998, Document ID 
0335; McDonald et al., 1995, 0371);
     Vermont Granite Workers (Attfield and Costello, 2004, 
Document ID 0285; Graham et al., 2004, 1031; Costello and Graham, 1988, 
0991; Davis et al., 1983, 0999);
     North American Industrial Sand Workers (Hughes et al., 
2001, Document ID 1060; McDonald et al., 2001, 1091; McDonald et al., 
2005, 1092; Rando et al., 2001, 0415; Sanderson et al., 2000, 0429; 
Steenland and Sanderson, 2001, 0455); and
     British Coal Miners (Miller et al., 2007, Document ID 
1305; Miller and MacCalman, 2009, 1306).
    OSHA considered these studies as providing the strongest evidence 
for several reasons. They were all retrospective cohort or case-control 
studies that demonstrated positive, statistically significant exposure-
response relationships between exposure to crystalline silica and lung 
cancer mortality. Except for the British pottery studies, where 
exposure-response trends were noted for average exposure only, lung 
cancer risk was found to be related to cumulative exposure. In general, 
these studies were of sufficient size and had adequate years of follow 
up, and had sufficient quantitative exposure data to reliably estimate 
exposures of cohort members. As part of their analyses, the authors of 
these studies also found positive exposure-response relationships for 
silicosis, indicating that underlying estimates of worker exposures 
were not likely to be substantially misclassified. Furthermore, the 
authors of these studies addressed potential confounding due to other 
carcinogenic exposures through study design or data analysis.
    In the diatomaceous earth industry, Checkoway et al. developed a 
``semi-quantitative'' cumulative exposure estimate that demonstrated a 
statistically significant positive exposure-response trend between 
duration of employment or cumulative exposure and lung cancer mortality 
(1993, Document ID 0324). The quartile analysis with a 15-year lag 
showed an increasing trend in relative risks (RR) of lung cancer 
mortality, with the highest exposure quartile having a RR of 2.74 for 
lung cancer mortality. Checkoway et al. conducted a re-analysis to 
address criticisms of potential confounding due to asbestos and again 
demonstrated a positive exposure-response risk gradient when 
controlling for asbestos exposure and other variables (1996, Document 
ID 0325). Rice et al. (2001, Document ID 1118) conducted a re-analysis 
and quantitative risk assessment of the Checkoway et al. (1997, 
Document ID 0326) study, finding that exposure to crystalline silica 
was a significant predictor of lung cancer mortality. OSHA included 
this re-analysis in its Preliminary QRA (Document ID 1711).
    In the British pottery industry, excess lung cancer risk was found 
to be associated with crystalline silica exposure among workers in a 
proportionate mortality ratio (PMR) study \4\ (McDonald et al., 1995, 
Document ID 0371) and in a cohort and nested case-control study \5\ 
(Cherry et al., 1998, Document ID 0335). In the former, elevated PMRs 
for lung cancer were found after adjusting for potential confounding by 
asbestos exposure. In the study by Cherry et al., odds ratios for lung 
cancer mortality were statistically significantly elevated after 
adjusting for smoking. Odds ratios were related to average, but not 
cumulative, exposure to crystalline silica.
---------------------------------------------------------------------------

    \4\ A PMR is the number of deaths within a population due to a 
specific disease (e.g., lung cancer) divided by the total number of 
deaths in the population during some time period.
    \5\ A cohort study is a study in which the occurrence of disease 
(e.g., lung cancer) is measured in a cohort of workers with 
potential for a common exposure (e.g., silica). A nested case-
control study is a study in which workers with disease are 
identified in an occupational cohort, and a control group consisting 
of workers without disease is selected (independently of exposure 
status) from the same cohort to determine whether there is a 
difference in exposure between cases and controls. A number of 
controls are matched to each case to control for potentially 
confounding factors, such as age, gender, etc.
---------------------------------------------------------------------------

    In the Vermont granite cohort, Costello and Graham (1988, Document 
ID 0991) and Graham et al. (2004, Document ID 1031) in a follow-up 
study found that workers employed prior to 1930 had an excess risk of 
lung cancer. Lung cancer mortality among granite workers hired after 
1940 (post-implementation of controls), however, was not elevated in 
the Costello and Graham study and was only somewhat elevated (not 
statistically significant) in the Graham et al. study. Graham et al. 
(2004, Document ID 1031) concluded that their results did not support a 
causal relationship between granite dust exposure and lung cancer 
mortality.
    Looking at the same population, Attfield and Costello (2004, 
Document ID 0285) developed a quantitative estimate of cumulative 
exposure (8 exposure categories) adapted from a job exposure matrix 
developed by Davis et al. (1983, Document ID 0999). They found a 
statistically significant trend between lung cancer mortality and log-
transformed cumulative exposure to crystalline silica. Lung cancer 
mortality rose reasonably consistently through the first seven 
increasing exposure groups, but fell in the highest cumulative exposure 
group. With the highest exposure group omitted, a strong positive dose-
response trend was found for both untransformed and log-transformed 
cumulative exposures. The authors explained that the highest exposure 
group would have included the most unreliable exposure estimates being 
reconstructed from exposures 20 years prior to study initiation when 
exposure estimation was less precise. OSHA expressed its belief that 
the study by Attfield and Costello (2004, Document ID 0285) was of 
superior design in that it used quantitative estimates of exposure and 
evaluated lung cancer mortality rates by exposure group. In contrast, 
the findings by Graham et al. (2004, Document ID 1031) were based on a 
dichotomous comparison of risk among high- versus low-exposure groups, 
where date-of-hire before and after implementation of ventilation 
controls was used as a surrogate for exposure. Consequently, OSHA used 
the Attfield and Costello study in its Preliminary QRA (Document ID 
1711). In its Supplemental Literature Review of Epidemiological Studies 
on Lung Cancer Associated with Exposure to Respirable Crystalline 
Silica, OSHA also discussed a more recent study of Vermont granite 
workers by Vacek et al. (2011, Document ID 1486) that did not find an 
association between silica exposure and lung cancer mortality (Document 
ID 1711, Attachment 1, pp. 2-5). (OSHA examines this study in great 
length in Section V.F, Comments and Responses Concerning Lung Cancer 
Mortality.)
    In the North American industrial sand industry, studies of two 
overlapping cohorts found a statistically significant increased risk of 
lung cancer mortality with increased cumulative exposure in both 
categorical and continuous analyses (Hughes et al., 2001, Document ID 
1060; McDonald et al., 2001, 1091; McDonald et al., 2005, 1092; Rando 
et al., 2001, 0415; Sanderson et al., 2000, 0429; Steenland and 
Sanderson, 2001, 0455). McDonald et al. (2001, Document ID 1091) 
examined a cohort that entered the workforce, on average, a decade 
earlier than the cohorts that Steenland and Sanderson (2001, Document 
ID 0455) examined. The McDonald cohort, drawn from eight plants, had 
more years of exposure in the industry (19 versus 8.8 years). The 
Steenland and Sanderson (2001, Document ID 0455) cohort worked in 16 
plants, 7 of which overlapped with the McDonald, et al.

[[Page 16308]]

(2001, Document ID 1091) cohort. McDonald et al. (2001, Document ID 
1091), Hughes et al. (2001, Document ID 1060), and Rando et al. (2001, 
Document ID 0415) had access to smoking histories, plant records, and 
exposure measurements that allowed for historical reconstruction and 
the development of a job exposure matrix. The McDonald et al. (2005, 
Document ID 1092) study was a later update, with follow-up through 
2000, of both the cohort and nested case-control studies. Steenland and 
Sanderson (2001, Document ID 0455) had limited access to plant 
facilities, less detailed historic exposure data, and used MSHA 
enforcement records for estimates of recent exposure. These studies 
(Hughes et al., 2001, Document ID 1060; McDonald et al., 2005, 1092; 
Steenland and Sanderson, 2001, 0455) showed very similar exposure-
response patterns of increased lung cancer mortality with increased 
exposure. OSHA included the quantitative exposure-response analysis 
from the Hughes et al. (2001, Document ID 1060) study in its 
Preliminary QRA, as it allowed for individual job, exposure, and 
smoking histories to be taken into account.
    OSHA noted that Brown and Rushton (2005a, Document ID 0303; 2005b, 
0304) found no association between risk of lung cancer mortality and 
exposure to respirable crystalline silica among British industrial sand 
workers. However, a large portion of the cohort had relatively short 
service times in the industry, with over one-half the cohort deaths and 
almost three-fourths of the lung cancer mortalities having had less 
than 10 years of service. Considering the apparent high turnover in 
this industry and the absence of prior occupational histories, 
exposures from work experience other than in the industrial sand 
industry could be a significant confounder (Document ID 1711, p. 131). 
Additionally, as Steenland noted in a letter review (2005a, Document ID 
1313), the cumulative exposures of workers in the Brown and Ruston 
(2005b, Document ID 0304) study were over 10 times lower than the 
cumulative exposures experienced by the cohorts in the pooled analysis 
that Steenland et al. (2001a, Document ID 0452) performed. The low 
exposures experienced by this cohort would have made detecting a 
positive association with lung cancer mortality even more difficult.
    In British coal miners, excess lung cancer mortality was reported 
in a large cohort study, which examined the mortality experience of 
17,800 miners through the end of 2005 (Miller et al., 2007, Document ID 
1305; Miller and MacCalman, 2009, 1306). By that time, the cohort had 
accumulated 516,431 person years of observation (an average of 29 years 
per miner), with 10,698 deaths from all causes. Overall lung cancer 
mortality was elevated (SMR = 115.7, 95% C.I. 104.8-127.7), and a 
positive exposure-response relationship with crystalline silica 
exposure was determined from Cox regression after adjusting for smoking 
history. Three of the strengths of this study were the detailed time-
exposure measurements of both quartz and total mine dust, detailed 
individual work histories, and individual smoking histories. For lung 
cancer, analyses based on Cox regression provided strong evidence that, 
for these coal miners, although quartz exposures were associated with 
increased lung cancer risk, simultaneous exposures to coal dust did not 
cause increased lung cancer risk. Because of these strengths, OSHA 
included this study in its Preliminary QRA (Document ID 1711).
    In addition to the studies in these cohorts, OSHA also reviewed 
studies of lung cancer mortality in metal ore mining populations. Many 
of these mining studies, which showed mixed results, were subject to 
confounding due to exposure to other potential carcinogens such as 
radon and arsenic. IARC noted that only a few ore mining studies 
accounted for confounding from other occupational carcinogens and that, 
when confounding was absent or accounted for, an association between 
silica exposure and lung cancer was absent (1997, Document ID 1062). 
Many of the studies conducted since IARC's review, however, more 
strongly implicate crystalline silica as a human carcinogen (1997, 
Document ID 1062). Pelucchi et al. (2006, Document ID 0408), in a meta-
analysis of studies conducted since IARC's (1997, Document ID 1062) 
review, reported statistically significantly elevated relative risks of 
lung cancer mortality in underground and surface miners in three cohort 
and four case-control studies. Cassidy et al., in a pooled case-control 
analysis, showed a statistically significant increased risk of lung 
cancer mortality among miners (OR = 1.48), and demonstrated a linear 
trend of increasing odds ratios with increasing exposures (2007, 
Document ID 0313).
    OSHA also preliminarily determined that the results of the studies 
conducted in three industry sectors (foundry, silicon carbide, and 
construction sectors) were confounded by the presence of exposures to 
other carcinogens. Exposure data from these studies were not sufficient 
to distinguish between exposure to silica dust and exposure to other 
occupational carcinogens. IARC previously made a similar determination 
in reference to the foundry industry. However, with respect to the 
construction industry, Cassidy et al. (2007, Document ID 0313), in a 
large European community-based case-control study, reported finding a 
clear linear trend of increasing odds ratios with increasing cumulative 
exposure to crystalline silica (estimated semi-quantitatively) after 
adjusting for smoking and exposure to insulation and wood dusts.
    In addition, an analysis of 4.8 million death certificates from 27 
states within the U.S. for the years 1982 to 1995 showed statistically 
significant excesses in lung cancer mortality, silicosis mortality, 
tuberculosis, and NMRD among persons with occupations involving medium 
and high exposure to respirable crystalline silica (Calvert et al., 
2003, Document ID 0309). A national records and death certificate study 
was also conducted in Finland by Pukkala et al., who found a 
statistically significant excess of lung cancer incidence among men and 
women with estimated medium and heavy exposures (2005, Document ID 
0412).
    One of the more compelling studies OSHA evaluated and used in the 
Preliminary QRA (Document ID 1711) was Steenland et al.'s (2001a, 
Document ID 0452) pooled analysis of 10 occupational cohorts (5 mines 
and 5 industrial facilities), which demonstrated an overall positive 
exposure-response relationship between cumulative exposure to 
crystalline silica and lung cancer mortality. These 10 cohorts included 
65,980 workers and 1,072 lung cancer deaths, and were selected because 
of the availability of raw data on exposure to crystalline silica and 
health outcomes. The investigators found lung cancer risk increased 
with increasing cumulative exposure, log cumulative exposure, and 
average exposure. Exposure-response trends were similar between mining 
and non-mining cohorts.
iii. Confounding
    Smoking is known to be a major risk factor for lung cancer. 
However, OSHA maintained in the Preliminary QRA that it is unlikely 
that smoking explained the observed exposure-response trends in the 
studies described above (Document ID 1711). Studies by Hnizdo et al. 
(1997, Document ID 1049), McLaughlin et al. (1992, Document ID 0372), 
Hughes et al. (2001, Document ID 1060), McDonald et al. (2001, Document 
ID 1091; 2005, 1092), Miller and MacCalman (2009, Document ID 1306), 
and Cassidy et al. (2007, Document ID 0313) had detailed smoking 
histories with sufficiently large

[[Page 16309]]

populations and a sufficient number of years of follow-up time to 
quantify the interaction between crystalline silica exposure and 
cigarette smoking. In a cohort of white South African gold miners 
(Hnizdo and Sluis-Cremer, 1991, Document ID 1051) and in the follow-up 
nested case-control study (Hnizdo et al., 1997, Document ID 1049), the 
combined effect of exposure to respirable crystalline silica and 
smoking was greater than additive, suggesting a multiplicative effect. 
This effect appeared to be greatest for miners with greater than 35 
pack-years of smoking and higher cumulative exposure to silica. In the 
Chinese nested case-control studies (McLaughlin et al., 1992, Document 
ID 0372), cigarette smoking was associated with lung cancer, but 
control for smoking did not influence the association between silica 
and lung cancer in the mining and pottery cohorts studied. The studies 
of industrial sand workers (Hughes et al., 2001, Document ID 1060) and 
British coal workers (Miller and MacCalman, 2009, Document ID 1306) 
found positive exposure-response trends after adjusting for smoking 
histories, as did Cassidy et al. (2007, Document ID 0313) in their 
community-based case-control study of exposed European workers.
    Given these findings of investigators who have accounted for the 
impact of smoking, OSHA preliminarily determined that the weight of the 
evidence reviewed identified respirable crystalline silica as an 
independent risk factor for lung cancer mortality. OSHA also determined 
that its finding was further supported by animal studies demonstrating 
that exposure to silica alone can cause lung cancer (e.g., Muhle et 
al., 1995, Document ID 0378).
iv. Lung Cancer and Silicosis
    Animal and in vitro studies have demonstrated that the early steps 
in the proposed mechanistic pathways that lead to silicosis and lung 
cancer seem to share some common features (see Document ID 1711, pp. 
171-172). This has led some researchers to suggest that silicosis is a 
prerequisite to lung cancer. Some have suggested that any increased 
lung cancer risk associated with silica may be a consequence of 
inflammation (and concomitant oxidative stress) and increased 
epithelial cell proliferation associated with the development of 
silicosis. However, other researchers have noted additional genotoxic 
and non-genotoxic mechanisms that may also be involved in 
carcinogenesis induced by silica (see Section V.H, Mechanisms of 
Silica-Induced Adverse Health Effects, and Document ID 1711, pp. 230-
239). IARC also noted that a direct genotoxic mechanism from silica to 
induce a carcinogenic effect cannot be ruled out (2012, Document ID 
1473). Thus, OSHA preliminarily concluded that available animal and in 
vitro studies do not support the hypothesis that development of 
silicosis is necessary for silica exposure to cause lung cancer.
    In general, studies of workers with silicosis, as well as meta-
analyses that include these studies, have shown that workers with 
radiologic evidence of silicosis have higher lung cancer risk than 
those without radiologic abnormalities or mixed cohorts. Three meta-
analyses attempted to look at the association of increasing ILO 
radiographic categories of silicosis with increasing lung cancer 
mortality. Two of these analyses (Kurihara and Wada, 2004, Document ID 
1084; Tsuda et al., 1997, 1127) showed no association with increasing 
lung cancer mortality, while Lacasse et al. (2005, Document ID 0365) 
demonstrated a positive dose-response for lung cancer with increasing 
ILO radiographic category. A number of other studies found increased 
lung cancer risk among exposed workers absent radiological evidence of 
silicosis (Cassidy et al., 2007, Document ID 0313; Checkoway et al., 
1999, 0327; Cherry et al., 1998, 0335; Hnizdo et al., 1997, 1049; 
McLaughlin et al., 1992, 0372). For example, the diatomaceous earth 
study by Checkoway et al. showed a statistically significant exposure-
response relationship for lung cancer among persons without silicosis 
(1999, Document ID 0327). Checkoway and Franzblau, reviewing the 
international literature, found that all epidemiological studies 
conducted to that date were insufficient to conclusively determine the 
role of silicosis in the etiology of lung cancer (2000, Document ID 
0323). OSHA preliminarily concluded that the more recent pooled and 
meta-analyses do not provide compelling evidence that silicosis is a 
necessary precursor to lung cancer.
c. Non-Malignant Respiratory Diseases (Other Than Silicosis)
    In addition to causing silicosis, exposure to crystalline silica 
has been associated with increased risks of other non-malignant 
respiratory diseases (NMRD), primarily chronic obstructive pulmonary 
disease (COPD), chronic bronchitis, and emphysema. COPD is a disease 
state characterized by airflow limitation that is usually progressive 
and not fully reversible. In patients with COPD, either chronic 
bronchitis or emphysema may be present or both conditions may be 
present together.
    As detailed in the Review of Health Effects Literature, OSHA 
reviewed several studies of NMRD morbidity and preliminarily concluded 
that exposure to respirable crystalline silica may increase the risk of 
emphysema, chronic bronchitis, and pulmonary function impairment, 
regardless of whether signs of silicosis are present (Document ID 
1711). Smokers may be at an increased risk relative to nonsmokers.
    OSHA also reviewed studies of NMRD mortality that focused on causes 
of death other than silicosis. Wyndham et al. found a significant 
excess mortality for chronic respiratory diseases in a cohort of white 
South African gold miners (1986, Document ID 0490). A case-referent 
analysis found that, although the major risk factor for chronic 
respiratory disease was smoking, there was a statistically significant 
additional effect of cumulative exposure to silica-containing dust. A 
multiplicative effect of smoking and cumulative dust exposure on 
mortality from COPD was found in another study of white South African 
gold miners (Hnizdo, 1990, Document ID 1045). Analysis of various 
combinations of dust exposure and smoking found a trend in odds ratios 
that indicated this synergism. There was a statistically significant 
increasing trend for dust particle-years and for cigarette-years of 
smoking.
    Park et al. (2002, Document ID 0405) analyzed the California 
diatomaceous earth cohort data originally studied by Checkoway et al. 
(1997, Document ID 0326), consisting of 2,570 diatomaceous earth 
workers employed for 12 months or more from 1942 to 1994, to quantify 
the relationship between exposure to cristobalite and mortality from 
chronic lung disease other than cancer (LDOC). Diseases in this 
category included pneumoconiosis (which included silicosis), chronic 
bronchitis, and emphysema, but excluded pneumonia and other infectious 
diseases. Smoking information was available for about 50 percent of the 
cohort and for 22 of the 67 LDOC deaths available for analysis, 
permitting at least partial adjustment for smoking. Using the exposure 
estimates developed for the cohort by Rice et al. (2001, Document ID 
1118) in their exposure-response study of lung cancer risks, Park et 
al. (2002, Document 0405) evaluated the quantitative exposure-response 
relationship for LDOC mortality and found a strong positive 
relationship with exposure to respirable crystalline silica. OSHA found 
this study particularly compelling because of the strengths of the 
study design and availability of smoking history data on part of the 
cohort, as well as the high-

[[Page 16310]]

quality exposure and job history data. The study authors noted:

    Data on smoking, collected since the 1960s in the company's 
radiographic screening programme, were available for 1171 of the 
subjects (50%). However, smoking habits were unknown for 45 of the 
67 workers that died from LDOC (67%). Our Poisson regression 
analyses for LDOC, stratified on smoking, have partially rectified 
the confounding by smoking issue. Furthermore, analyses performed 
without control for smoking produced slightly smaller and less 
precise estimates of the effects of silica, suggesting that smoking 
is a negative confounder. In their analysis of this cohort, 
Checkoway et al. applied the method of Axelson concluding that it 
was very unlikely that cigarette smoking could account for the 
association found between mortality from LDOC and cumulative 
exposure to silica (Document ID 0405, p. 41).

    Consequently, OSHA used this study in its Preliminary QRA (Document 
ID 1711, pp. 295-298).
    Based on this evidence, and the other studies discussed in the 
Review of Health Effects Literature, OSHA preliminarily concluded that 
respirable crystalline silica increases the risk for mortality from 
non-malignant respiratory disease (not including silicosis) in an 
exposure-related manner. The Agency also preliminarily concluded that 
the risk is strongly influenced by smoking, and opined that the effects 
of smoking and silica exposure may be synergistic.
d. Renal Disease and Autoimmune Diseases
    In its Review of Health Effects Literature, OSHA described the 
available experimental and epidemiological data evaluating respirable 
crystalline silica exposure and renal and/or autoimmune effects 
(Document ID 1711). In addition to a number of case reports, 
epidemiological studies have found statistically significant 
associations between occupational exposure to silica dust and chronic 
renal disease (Calvert et al., 1997, Document ID 0976), subclinical 
renal changes (Ng et al., 1992c, Document ID 0386), end-stage renal 
disease morbidity (Steenland et al., 1990, Document ID 1125), chronic 
renal disease mortality (Steenland et al., 2001b, Document ID 0456; 
2002a, 0448), and granulomatosis with polyangitis, a condition that can 
affect the kidneys (Nuyts et al., 1995, Document ID 0397). In other 
findings, silica-exposed individuals, both with and without silicosis, 
had an increased prevalence of abnormal renal function (Hotz et al., 
1995, Document ID 0361), and renal effects have been reported to 
persist after cessation of silica exposure (Ng et al., 1992c, Document 
ID 0386). Possible mechanisms suggested for silica-induced renal 
disease include a direct toxic effect on the kidney, deposition of 
immune complexes (IgA) in the kidney following silica related pulmonary 
inflammation, and an autoimmune mechanism (Calvert et al., 1997, 
Document ID 0976; Gregorini et al., 1993, 1032).
    In a pooled cohort analysis, Steenland et al. (2002a, Document ID 
0448) combined the industrial sand cohort from Steenland et al. (2001b, 
Document ID 0456), the gold mining cohort from Steenland and Brown 
(1995a, Document ID 0450), and the Vermont granite cohort studies by 
Costello and Graham (1988, Document ID 0991). In all, the combined 
cohort consisted of 13,382 workers with exposure information available 
for 12,783. The analysis demonstrated statistically significant 
exposure-response trends for acute and chronic renal disease mortality 
with quartiles of cumulative exposure to respirable crystalline silica. 
In a nested case-control study design, a positive exposure-response 
relationship was found across the three cohorts for both multiple-cause 
mortality (i.e., any mention of renal disease on the death certificate) 
and underlying cause mortality. Renal disease risk was most prevalent 
among workers with cumulative exposures of 500 [micro]g/m\3\ or more 
(Steenland et al., 2002a, Document ID 0448).
    OSHA noted that other studies failed to find an excess renal 
disease risk among silica-exposed workers. Davis et al. (1983, Document 
ID 0999) found elevated, but not statistically significant, mortality 
from diseases of the genitourinary system among Vermont granite shed 
workers. There was no observed relationship between mortality from this 
cause and cumulative exposure. A similar finding was reported by 
Koskela et al. (1987, Document ID 0363) among Finnish granite workers, 
where there were 4 deaths due to urinary tract disease compared to 1.8 
expected. Both Carta et al. (1994, Document ID 0312) and Cocco et al. 
(1994, Document ID 0988) reported finding no increased mortality from 
urinary tract disease among workers in an Italian lead mine and zinc 
mine. However, Cocco et al. (1994, Document ID 0988) commented that 
exposures to respirable crystalline silica were low, averaging 7 and 90 
[micro]g/m\3\ in the two mines, respectively, and that their study in 
particular had low statistical power to detect excess mortality.
    OSHA expressed its belief that there is substantial evidence, 
particularly the 3-cohort pooled analysis conducted by Steenland et al. 
(2002a, Document ID 0448), on which to base a finding that exposure to 
respirable crystalline silica increases the risk of renal disease 
mortality and morbidity. The pooled analysis by Steenland et al. 
involved a large number of workers from three cohorts with well-
documented, validated job-exposure matrices; it found a positive, 
monotonic increase in renal disease risk with increasing exposure for 
both underlying and multiple cause data (2002a, Document ID 0448). 
However, there are considerably less data available for renal disease 
than there are for silicosis mortality and lung cancer mortality. The 
findings based on these data are, therefore, less robust. Nevertheless, 
OSHA preliminarily concluded that the underlying data are sufficient to 
provide useful estimates of risk and included the Steenland et al. 
(2002a, Document ID 0448) analysis in its Preliminary QRA.
    For autoimmune effects, OSHA reviewed epidemiological information 
suggesting an association between respirable silica exposure and 
autoimmune diseases, including scleroderma (Sluis-Cremer et al., 1985, 
Document ID 0439), rheumatoid arthritis (Klockars et al., 1987, 
Document ID 1075; Rosenman and Zhu, 1995, 0424), and systemic lupus 
erythematosus (Brown et al., 1997, Document ID 0974). However, there 
were no quantitative exposure-response data available on which to base 
a quantitative risk assessment for autoimmune diseases.
e. Physical Factors Affecting Toxicity of Crystalline Silica
    OSHA also examined evidence on the comparative toxicity of the 
silica polymorphs (quartz, cristobalite, and tridymite). A number of 
animal studies appear to suggest that cristobalite and tridymite are 
more toxic to the lung than quartz and more tumorigenic (e.g., King et 
al., 1953, Document ID 1072; Wagner et al., 1980, 0476). However, in 
contrast to these findings, several authors have reviewed the studies 
done in this area and concluded that cristobalite and tridymite are not 
more toxic than quartz (e.g., Bolsaitis and Wallace, 1996, Document ID 
0298; Guthrie and Heaney, 1995, 1035). Furthermore, a difference in 
toxicity between cristobalite and quartz has not been observed in 
epidemiological studies (tridymite has not been studied) (NIOSH, 2002, 
Document ID 1110). In an analysis of exposure-response for lung cancer, 
Steenland et al. found similar exposure-response trends between 
cristobalite-exposed workers and other cohorts

[[Page 16311]]

exposed to quartz (2001a, Document ID 0452).
    OSHA also discussed other physical factors that may influence the 
toxicologic potency of crystalline silica. A number of animal studies 
compared the toxicity of freshly fractured silica to that of aged 
silica (Porter et al., 2002, Document ID 1114; Shoemaker et al., 1995, 
0437; Vallyathan et al., 1995, 1128). These studies have demonstrated 
that although freshly fractured silica is more toxic than aged silica, 
aged silica still retains significant toxicity. There have been no 
studies comparing workers exposed to freshly fractured silica to those 
exposed to aged silica. However, similarities between the results of 
animal and human studies involving freshly fractured silica suggest 
that the animal studies involving aged silica may also apply to humans. 
For example, studies of workers exposed to freshly fractured silica 
have demonstrated that these workers exhibit the same cellular effects 
as seen in animals exposed to freshly fractured silica (Castranova et 
al., 1998, Document ID 1294; Goodman et al., 1992, 1029). Animal 
studies also suggest that pulmonary reactions of rats to short-duration 
exposure to freshly fractured silica mimic those seen in acute 
silicosis in humans (Vallyathan et al., 1995, Document ID 1128).
    Surface impurities, particularly metals, have been shown to alter 
silica toxicity. Iron, depending on its state and quantity, has been 
shown to either increase or decrease toxicity (see Document ID 1711, 
pp. 247-258). Aluminum has been shown to decrease toxicity (Castranova 
et al., 1997, Document ID 0978; Donaldson and Borm, 1998, 1004; Fubini, 
1998, 1016). Silica coated with aluminosilicate clay exhibits lower 
toxicity, possibly as a result of reduced bioavailability of the silica 
particle surface (Donaldson and Borm, 1998, Document ID 1004; Fubini, 
1998, 1016). Aluminum as well as other metal ions are thought to modify 
silanol groups on the silica surface, thus decreasing the membranolytic 
and cytotoxic potency and resulting in enhanced particle clearance from 
the lung before damage can take place (Fubini, 1998, Document ID 1016). 
An epidemiological study found that the risk of silicosis was less in 
pottery workers than in tin and tungsten miners (Chen et al., 2005, 
Document ID 0985; Harrison et al., 2005, 1036), possibly reflecting 
that pottery workers were exposed to silica particles having less 
biologically-available, non-clay-occluded surface area than was the 
case for miners.
    Although it is evident that a number of factors can act to mediate 
the toxicological potency of crystalline silica, it is not clear how 
such considerations should be taken into account to evaluate lung 
cancer and silicosis risks to exposed workers. After evaluating many in 
vitro studies that investigated the surface characteristics of 
crystalline silica particles and their influence on fibrogenic 
activity, NIOSH concluded that further research is needed to associate 
specific surface characteristics that can affect toxicity with specific 
occupational exposure situations and consequent health risks to workers 
(2002, Document ID 1110). Thus, OSHA preliminarily concluded that while 
there was considerable evidence that several environmental influences 
can modify surface activity to either enhance or diminish the toxicity 
of silica, the available information was insufficient to determine in 
any quantitative way how these influences may affect disease risk to 
workers in any particular workplace setting.
3. Summary of the Preliminary QRA
    OSHA presented in the Preliminary QRA estimates of the risk of 
silica-related diseases assuming exposure over a working life (45 
years, from age 20 to age 65) to the revised 8-hour time-weighted 
average (TWA) PEL of 50 [micro]g/m\3\ respirable crystalline silica, 
the new action level of 25 [micro]g/m\3\, and the previous PELs. OSHA's 
previous general industry PEL for respirable quartz was expressed both 
in terms of a particle count formula and a gravimetric concentration 
formula; the previous construction and shipyard employment PELs for 
respirable quartz were only expressed in terms of a particle count 
formula. For general industry, as the quartz content increases, the 
gravimetric PEL approached a limit of 100 [micro]g/m\3\ respirable 
quartz. For construction and shipyard employment, OSHA's previous PELs 
used a formula that limits exposure to respirable dust, depending upon 
the quartz content, expressed as a respirable particle count 
concentration. There was no single mass concentration equivalent for 
the construction and shipyard employment PELs; OSHA reviewed several 
studies that suggest that the previous construction/shipyard PEL likely 
was between 250 and 500 [micro]g/m\3\ respirable quartz. In general 
industry, for both the gravimetric and particle count PELs, OSHA's 
previous PELs for cristobalite and tridymite were half the value for 
quartz. Based upon these previous PELs and the new action level, OSHA 
presented risk estimates associated with exposure over a working life 
to 25, 50, 100, 250, and 500 [micro]g/m\3\ respirable silica 
(corresponding to cumulative exposures over 45 years to 1.125, 2.25, 
4.5, 11.25, and 22.5 mg/m\3\-yrs).
    To estimate lifetime excess mortality risks at these exposure 
levels, OSHA implemented each of the risk models in a life table 
analysis that accounted for competing causes of death due to background 
causes and cumulated risk through age 85. For these analyses, OSHA used 
lung cancer, NMRD, or renal disease mortality and all-cause mortality 
rates to account for background risks and competing risks (U.S. 2006 
data for lung cancer and NMRD mortality in all males, 1998 data for 
renal disease mortality, obtained from cause-specific death rate tables 
published by the National Center for Health Statistics (2009, Document 
ID 1104)). OSHA calculated these risk estimates assuming occupational 
exposure from age 20 to age 65. The mortality risk estimates were 
presented in terms of lifetime excess risk per 1,000 workers for 
exposure over an 8-hour working day, 250 days per year, and a 45-year 
working life.
    For silicosis morbidity, OSHA based its risk estimates on 
cumulative risk models used by various investigators to develop 
quantitative exposure-response relationships. These models 
characterized the risk of developing silicosis (as detected by chest 
radiography) up to the time that cohort members (including both active 
and retired workers) were last examined. Thus, risk estimates derived 
from these studies represented less-than-lifetime risks of developing 
radiographic silicosis. OSHA did not attempt to estimate lifetime risk 
(i.e., up to age 85) for silicosis morbidity because the relationships 
between age, time, and disease onset post-exposure have not been well 
characterized.
a. Silicosis and NMRD Mortality
i. Exposure-Response Studies
    In the Preliminary QRA, OSHA relied upon two published quantitative 
risk studies of silicosis and NMRD mortality (Document ID 1711). The 
first, Mannetje et al. (2002b, Document ID 1089) conducted a pooled 
analysis of silicosis mortality in which there were 18,634 subjects, 
150 silicosis deaths, and 20 deaths from unspecified pneumoconiosis. 
Rates for silicosis adjusted for age, calendar time, and study were 
estimated by Poisson regression and increased nearly monotonically with 
deciles of cumulative exposure, from a mortality rate of 5/100,000 
person-years in the lowest exposure category (0-0.99

[[Page 16312]]

mg/m\3\-yrs) to 299/100,000 person-years in the highest category 
(>28.10 mg/m\3\-yrs).
    As previously discussed, the second, Park et al. (2002, Document ID 
0405) analyzed the California diatomaceous earth cohort data from 
Checkoway et al. (1997, Document ID 0326), and examined mortality from 
chronic lung disease other than cancer (LDOC; also known as non-
malignant respiratory disease (NMRD)). Smoking information was 
available for about 50 percent of the cohort and for 22 of the 67 LDOC 
deaths available for analysis, permitting Park et al. (2002, Document 
ID 0405) to partially adjust for smoking. Estimates of LDOC mortality 
risks were derived via Poisson and Cox proportional hazards models; a 
variety of relative rate model forms were fit to the data, with a 
linear relative rate model selected for estimating risks.
ii. Risk Estimates
    As silicosis is only caused by exposure to respirable crystalline 
silica (i.e., there is no background rate of silicosis in the unexposed 
population), absolute risks of silicosis mortality rather than excess 
risks were calculated for the Mannetje et al. pooled analysis (2002b, 
Document ID 1089). These risk estimates were derived from the rate 
ratios incorporating simulated measurement error reported by 
ToxaChemica (Document ID 0469). OSHA's estimate of lifetime risk of 
silicosis mortality, for 45 years of exposure to the previous general 
industry PEL, was 11 deaths per 1,000 workers for the pooled analysis 
(Document ID 1711). At the revised PEL, the risk estimate was 7 deaths 
per 1,000.
    OSHA also calculated preliminary risk estimates for NMRD mortality. 
These estimates were derived from Park et al. (2002, Document ID 0405). 
For 45 years of exposure to the previous general industry PEL, OSHA 
preliminarily estimated lifetime excess risk at 83 deaths per 1,000 
workers. At the revised PEL, OSHA estimated 43 deaths per 1,000 
workers.
    OSHA noted that, for exposures up to 250 [micro]g/m\3\, the 
mortality risk estimates based on Park et al. (2002, Document ID 0405) 
are about 5 to 11 times as great as those calculated for the pooled 
analysis of silicosis mortality (Mannetje et al., 2002b, Document ID 
1089). These two sets of risk estimates, however, are not directly 
comparable, as the endpoint for the Park et al. (2002, Document ID 
0405) analysis was death from all non-cancer lung diseases, including 
pneumoconiosis, emphysema, and chronic bronchitis, whereas the pooled 
analysis by Mannetje et al. (2002b, Document ID 1089) included only 
deaths coded as silicosis or other pneumoconiosis. Less than 25 percent 
of the LDOC deaths in the Park et al. analysis were coded as silicosis 
or other pneumoconiosis (15 of 67), suggesting that silicosis as a 
cause of death may be misclassified as emphysema or chronic bronchitis. 
Thus, Mannetje et al.'s (2002b, Document ID 1089) selection of deaths 
may tend to underestimate the true risk of silicosis mortality, and 
Park et al.'s (2002, Document ID 0405) analysis may more completely 
capture the total respiratory mortality risk from all non-malignant 
causes.
    Since the time of OSHA's analysis, NCHS has released updated all-
cause mortality and NMRD mortality background rates from 2011 (http://wonder.cdc.gov/ucd-icd10.html); OSHA's final risk estimates for NMRD 
mortality, which incorporate these updated rates (ICD10 codes J40-J47, 
chronic lower respiratory diseases; J60-J66, J68, pneumoconiosis and 
chemical effects), are available in Section VI, Final Quantitative Risk 
Assessment and Significance of Risk.
b. Lung Cancer Mortality
i. Exposure-Response Studies
    In 1997, when IARC determined that there was sufficient evidence to 
regard crystalline silica as a human carcinogen, it also noted that 
some epidemiological studies did not demonstrate an excess risk of lung 
cancer and that exposure-response trends were not always consistent 
among studies that were able to describe such trends (Document ID 
1062). These findings led Steenland et al. (2001a, Document ID 0452) to 
conduct a comprehensive exposure-response analysis--the IARC multi-
center study--of the risk of lung cancer associated with exposure to 
crystalline silica. This study relied on all available cohort data from 
previously-published epidemiological studies for which there were 
adequate quantitative data on worker silica exposures to derive pooled 
estimates of disease risk. In addition, as discussed previously, OSHA 
identified four more recent studies suitable for quantitative risk 
assessment: (1) An exposure-response analysis by Rice et al. (2001, 
Document ID 1118) of a cohort of diatomaceous earth workers primarily 
exposed to cristobalite; (2) an analysis by Attfield and Costello 
(2004, Document ID 0285) of U.S. granite workers; (3) an exposure-
response analysis by Hughes et al. (2001, Document ID 1060) of U.S. 
industrial sand workers; and (4) a risk analysis by Miller et al. 
(2007, Document ID 1305) and Miller and MacCalman (2009, Document ID 
1306) of British coal miners. OSHA thoroughly described each of these 
studies in its Preliminary QRA (Document ID 1711); a brief summary of 
the exposure-response models used in each study is provided here.
    The Steenland et al. pooled exposure-response analysis was based on 
data obtained from ten cohorts of silica-exposed workers (65,980 
workers, 1,072 lung cancer deaths) (2001a, Document ID 0452). The 
pooled analysis cohorts included U.S. gold miners (Steenland and Brown, 
1995a, Document ID 0450), U.S. diatomaceous earth workers (Checkoway et 
al., 1997, Document ID 0326), Australian gold miners (de Klerk and 
Musk, 1998, Document ID 0345), Finnish granite workers (Koskela et al., 
1994, Document ID 1078), U.S. industrial sand employees (Steenland and 
Sanderson, 2001, Document ID 0455), Vermont granite workers (Costello 
and Graham, 1988, Document ID 0991), South African gold miners (Hnizdo 
and Sluis-Cremer, 1991, Document ID 1051; Hnizdo et al.,1997, 1049), 
and Chinese pottery workers, tin miners, and tungsten miners (Chen et 
al., 1992, Document ID 0329).
    Steenland et al. (2001a, Document ID 0452) performed a nested case-
control analysis via Cox regression. There were 100 controls chosen for 
each case randomly from among cohort members who survived past the age 
at which the case died; controls were matched on age (the time variable 
in Cox regression), study, race/ethnicity, sex, and date of birth 
within 5 years. Steenland et al. found that the use of any of the 
following continuous exposure variables in a log linear relative risk 
model resulted in positive statistically significant (p <= 0.05) 
exposure-response coefficients: (1) Cumulative exposure with a 15-year 
lag; (2) the log of cumulative exposure with a 15-year lag; and (3) 
average exposure (2001a, Document ID 0452). The models that provided 
the best fit to the data used cumulative exposure and log-transformed 
cumulative exposure. Models that used log-transformed cumulative 
exposure also showed no statistically significant heterogeneity among 
cohorts (p = 0.36), possibly because they are less influenced by very 
high exposures. At OSHA's request, Steenland (2010, Document ID 1312) 
also conducted a categorical analysis of the pooled data set and 
additional analyses using linear relative risk models (with and without 
the log transformation of cumulative exposure) as well as a two-piece 
spline model (see Document ID 1711, pp. 276-278).

[[Page 16313]]

    Rice et al. (2001, Document ID 1118) applied a variety of exposure-
response models to the California diatomaceous earth cohort data 
originally studied by Checkoway et al. (1993, Document ID 0324; 1996, 
0325; 1997, 0326) and included in the Steenland et al. (2001a, Document 
ID 0452) pooled analysis. The cohort consisted of 2,342 white males 
employed for at least one year between 1942 and 1987 in a California 
diatomaceous earth mining and processing plant. The cohort was followed 
until 1994, and included 77 lung cancer deaths. Rice et al. reported 
that exposure to crystalline silica was a significant predictor of lung 
cancer mortality for nearly all of the models employed, with the linear 
relative risk model providing the best fit to the data in the Poisson 
regression analysis (2001, Document ID 1118).
    Attfield and Costello (2004, Document ID 0285) analyzed the U.S. 
granite cohort originally studied by Costello and Graham (1988, 
Document ID 0991) and Davis et al. (1983, Document ID 0999) and 
included in the Steenland et al. (2001a, Document ID 0452) pooled 
analysis. The cohort consisted of 5,414 male granite workers who were 
employed in the Vermont granite industry between 1950 and 1982 and who 
had received at least one chest x-ray from the surveillance program of 
the Vermont Department of Industrial Hygiene. The 2004 report by 
Attfield and Costello extended follow-up from 1982 to 1994, and found 
201 deaths (Document ID 0285). Using Poisson regression models, the 
results of a categorical analysis showed a generally increasing trend 
of lung cancer rate ratios with increasing cumulative exposure.
    As mentioned previously, however, the rate ratio for the highest 
exposure group in the Attfield and Costello analysis (cumulative 
exposures of 6.0 mg/m\3\-yrs or higher) was substantially lower than 
that for other exposure groups (2004, Document ID 0285). The authors 
reported that the best-fitting model had a 15-year lag, untransformed 
cumulative exposure, and the omission of this highest exposure group. 
The authors argued that it was appropriate to omit the highest exposure 
group for several reasons, including that the exposure estimates for 
the highest exposure group were less reliable, and there was a greater 
likelihood of cohort selection effects, competing causes of death, and 
misdiagnosis (Document ID 0285, p. 136).
    McDonald et al. (2001, Document ID 1091), Hughes et al. (2001, 
Document ID 1060) and McDonald et al. (2005, Document ID 1092) followed 
up on a cohort study of North American industrial sand workers included 
in the Steenland et al. (2001a, Document ID 0452) pooled analysis. The 
McDonald et al. cohort included 2,670 men employed before 1980 for 
three years or more in one of nine North American (8 U.S. and 1 
Canadian) sand-producing plants, including 1 large associated office 
complex (2001, Document ID 1091). A nested case-control study based on 
90 lung cancer deaths (through 1994) from this cohort was conducted by 
Hughes et al. (2001, Document ID 1060). A subsequent update (through 
2000, 105 lung cancer deaths) eliminated the Canadian plant, following 
2,452 men from the eight U.S. plants (McDonald et al., 2005, Document 
ID 1092). These nested case-control studies, Hughes et al. (2001, 
Document ID 1060) and McDonald et al. (2005, Document ID 1092), allowed 
for individual job, exposure, and smoking histories to be taken into 
account in the exposure-response analysis. Hughes et al. (2001, 
Document ID 1060) found statistically significant positive exposure-
response trends for lung cancer for both cumulative exposure (lagged 15 
years) and average exposure concentration, but not for duration of 
employment. With exposure lagged 15 years and after adjusting for 
smoking, increasing quartiles of cumulative silica exposure were also 
associated with lung cancer mortality (p-value for trend = 0.04). 
McDonald et al. (2005, Document ID 1092) found very similar results, 
with increasing quartiles of cumulative silica exposure (lagged 15 
years) associated with lung cancer mortality (p-value for trend = 
0.006). Because McDonald et al. (2005, Document ID 1092) did not report 
the medians of the exposure categories, and given the similar results 
of both case-control studies, OSHA chose to base its risk estimates on 
the Hughes et al. (2001, Document ID 1060) study.
    Miller et al. (2007, Document ID 1305) and Miller and MacCalman 
(2009, Document ID 1306) continued a follow-up mortality study, begun 
in 1970, of coal miners from 10 British coal mines initially followed 
through the end of 1992 (Miller et al., 1997, Document ID 1304) and 
extended it to 2005. In the analysis using internal controls and Cox 
regression methods, the relative risk of lung cancer mortality, 
adjusted for concurrent dust exposure and smoking status, at a 
cumulative quartz exposure (lagged 15 years) equivalent of 
approximately 55 [mu]g/m\3\ for 45 years was 1.14 (95% C.I., 1.04 to 
1.25).
ii. Risk Estimates
    In the Preliminary QRA, OSHA presented estimates of excess lung 
cancer mortality risk from occupational exposure to crystalline silica, 
based on data from the five epidemiology studies discussed above 
(Document ID 1711). In its preliminary analysis, OSHA used background 
all-cause mortality and lung cancer mortality rates from 2006, as 
reported by the National Center for Health Statistics (NCHS) (Document 
ID 1104). These rates were used in life table analyses to estimate 
lifetime risks at the exposure levels of interest, ranging from 25 to 
500 [mu]g/m\3\ respirable crystalline silica.
    OSHA's preliminary estimates of lifetime excess lung cancer risk 
associated with 45 years of exposure to crystalline silica at 100 
[mu]g/m\3\ (approximately the previous general industry PEL) ranged 
between 13 and 60 deaths per 1,000 workers, depending upon the study 
used. For exposure to the revised PEL of 50 [mu]g/m\3\, the lifetime 
risk estimates were in the range of between 6 and 26 deaths per 1,000 
workers, depending upon the study used. For a 45 year exposure at the 
new action level of 25 [mu]g/m\3\, OSHA estimated the risk to range 
between 3 and 23 deaths per 1,000 workers. The Agency found that the 
results from these preliminary assessments were reasonably consistent 
despite the use of data from different cohorts and the reliance on 
different analytical techniques for evaluating dose-response 
relationships.
    OSHA also estimated the lung cancer risk associated with 45 years 
of exposure to the previous construction/shipyard PEL (in the range of 
250 [mu]g/m\3\ to 500 [mu]g/m\3\) to range between 37 and 653 deaths 
per 1,000 workers, depending upon the study used. OSHA acknowledges 
that the 653 deaths is the upper limit for 45 years of exposure to 500 
[mu]g/m\3\, and recognizes that actual risk, to the extent that workers 
are exposed for less than 45 years or intermittently, is likely to be 
lower. In addition, exposure to 250 or 500 [mu]g/m\3\ over 45 years 
represents cumulative exposures of 11.25 and 22.5 mg/m\3\-yrs, 
respectively. This range of cumulative exposure is well above the 
median cumulative exposure for most of the cohorts used in the 
preliminary risk assessment. Thus, OSHA explained that estimating lung 
cancer excess risks over this higher range of cumulative exposures of 
interest to OSHA required some degree of upward extrapolation of the 
exposure-response function to model these high exposures, thus adding 
uncertainty to the estimates.
    Since the time of that original analysis, NCHS has released updated 
all-cause mortality and lung cancer mortality background rates from 
2011.

[[Page 16314]]

OSHA's final risk estimates, which incorporate these updated rates, are 
available in this preamble at Section VI, Final Quantitative Risk 
Assessment and Significance of Risk.
c. Uncertainty Analysis of Pooled Studies of Lung Cancer Mortality and 
Silicosis Mortality
    In the Preliminary QRA, OSHA recognized that risk estimates can be 
inherently uncertain and can be affected by confounding, selection 
bias, and measurement error (Document ID 1711). OSHA presented several 
reasons as to why it does not believe that confounding or selection 
bias had a substantial impact on the risk estimates for lung cancer or 
silicosis mortality (Document ID 1711, pp. 299-302). However, because 
it was more difficult to assess the importance of exposure measurement 
error, OSHA's contractor, ToxaChemica, Inc., commissioned Drs. Kyle 
Steenland and Scott Bartell to perform an uncertainty analysis to 
examine the effect of uncertainty due to measurement error in the 
pooled studies (Steenland et al., 2001a, Document ID 0452; Mannetje 
2002b, 1089) on the lung cancer and silicosis mortality risk estimates 
(ToxaChemica, Inc., 2004, Document ID 0469).
    There are two main sources of error in the silica exposure 
measurements. The first arises from the assignment of individual 
workers' exposures based on either exposure measurements for a sample 
of workers in the same job or estimated exposure levels for specific 
jobs in the past when no measurements were available, via a job-
exposure matrix (JEM) (Mannetje et al., 2002a, Document ID 1090). The 
second arises from the conversion of historically-available dust 
measurements, typically particle count concentrations, to gravimetric 
respirable silica concentrations. ToxaChemica, Inc. conducted an 
uncertainty analysis using the raw data from the IARC multi-centric 
study to address these sources of error (2004, Document ID 0469).
i. Lung Cancer Mortality
    To examine the effect of error in the assignment of individual 
exposure values in the cohorts studied by Steenland et al. (2001a, 
Document ID 0452), ToxaChemica, Inc. used a Monte Carlo analysis (a 
type of simulation analysis that varies the values of an uncertain 
input to an analysis--in this case, exposure estimates--to explore the 
effects of different values on the outcome of the analysis) to randomly 
sample new values for each worker's job-specific exposure levels from a 
distribution that they believed characterized the variability in 
exposures of individual workers in each job (see Document ID 1711, pp. 
303-305). That is, ToxaChemica created a distribution of values for 
each member of each cohort where the mean exposure for each member was 
equal to the original exposure value and the distribution of exposure 
values was based on a log-normal distribution having a standard 
deviation that was based on the exposure variation observed in 
industrial sand plants observed by Steenland and Sanderson (2001, 
Document ID 0455). From this distribution, new sets of exposure values 
from each cohort member were randomly drawn for 50 trials. This 
simulation was designed to test whether sets of exposure values that 
were plausibly different from the original estimates would lead to 
substantially different results of the exposure-response analysis. 
Except for the simulated exposure values and the correction of a few 
minor errors in the original data sets, the simulation analysis used 
the same data as the original analyses conducted by Steenland et al. 
(2001a, Document ID 0452).
    When an entire set of cumulative exposure values was assembled for 
all workers based on these randomly sampled values, the set was used in 
a conditional logistic regression to fit a new exposure-response model. 
The extent to which altering the exposure values led to changes in the 
results indicated how sensitive the previously presented risk estimates 
may have been to error in the exposure estimates. Among the individual 
cohorts, most of the mean regression coefficients resulting from the 
simulation analysis were consistent with the coefficients from the 
exposure-response analyses reported in Steenland et al. (2001, Document 
ID 0455) and ToxaChemica, Inc. (2004, Document ID 0469) (following 
correction for minor data entry and rounding errors). An exception was 
the mean of the simulation coefficients based on the South Africa gold 
cohort (0.26), which was lower than the previously calculated exposure 
coefficient (0.582). ToxaChemica, Inc. (2004, Document ID 0469) 
concluded that this error source probably did not appreciably change 
the estimated exposure-response coefficient for the pooled data set.
    To examine the effect of error in estimating gravimetric respirable 
crystalline silica exposures from historical dust concentration data 
(i.e., particle count data), ToxaChemica, Inc. (2004, Document ID 0469) 
used a procedure similar to that used to assess uncertainties in 
individual exposure value assignments. ToxaChemica, Inc. assumed that, 
for each job in the dataset, a specific conversion factor existed that 
related workers' exposures measured as particle concentrations to 
gravimetric respirable silica exposures, and that this conversion 
factor came from a normal distribution with a standard deviation 
[sigma] = \1/2\ its mean [mu]. The use of a normal distribution was a 
reasonable choice in that it allowed the sampled conversion factors to 
fall above or below the original values with equal probability, as the 
authors had no information to suggest that error in either direction 
was more likely. The normal distribution also assigned higher 
probability to conversion values closer to the original values. The 
choice of the normal distribution therefore reflected the study 
authors' judgment that their original conversion factors were more 
likely to be approximately correct than not, while allowing for the 
possibility of significant error in the original values.
    A new conversion factor was then sampled for each job from the 
appropriate distribution, and the complete set of sampled conversion 
factors was then used to re-run the risk analysis used by Steenland et 
al. (2001a, Document ID 0452). The results were similar to the 
coefficients originally derived from each cohort; the only coefficient 
substantially affected by the procedure was that for the South African 
cohort, with an average value of 0.350 across ten runs compared to the 
original value of 0.582 (see Table II-5, Document ID 1711, p. 307). 
This suggests that the results of exposure-response analyses conducted 
using the South African cohort are sensitive to error in exposure 
estimates; therefore, there is greater uncertainty due to potential 
exposure estimation error in an exposure-response model based on this 
cohort than is the case for the other nine cohorts in Steenland et al's 
analysis.
    To explore the potential effects of both kinds of random 
uncertainty described above, ToxaChemica, Inc. (2004, Document ID 0469) 
used the distributions representing the error in job-specific exposure 
assignment and the error in converting exposure metrics to generate 50 
new exposure simulations for each cohort. A study-specific coefficient 
and a pooled coefficient were fit for each new simulation, with the 
assumption that the two sources of uncertainty were independent. The 
results indicated that the only cohort for which the mean of the 
exposure coefficients derived from the 50 simulations differed 
substantially from the previously calculated exposure

[[Page 16315]]

coefficient was the South African gold cohort (simulation mean of 0.181 
vs. original coefficient of 0.582). For the pooled analysis, the mean 
coefficient estimate from the simulations was 0.057, just slightly 
lower than the previous estimate of 0.060. Based on these results, OSHA 
concludes that random error in the underlying exposure estimates in the 
Steenland et al. (2001a, Document ID 0452) pooled cohort study of lung 
cancer is not likely to have substantially influenced the original risk 
estimates derived from the pooled data set, although the model 
coefficient for one of the ten cohorts (the South African gold miner 
cohort) appeared to be sensitive to measurement errors (see Table II-5, 
Document ID 1711, p. 307).
    Drs. Steenland and Bartell also examined the effects of systematic 
bias in conversion factors, considering the possibility that these may 
have been consistently under-estimated or over-estimated for any given 
cohort. They addressed possible biases in either direction, conducting 
simulations where the true silica content was assumed to be either half 
or double the estimated silica content of measured exposures. For the 
conditional logistic regression model using log cumulative exposure 
with a 15-year lag, doubling or halving the exposure for a specific 
study resulted in virtually no change in the exposure-response 
coefficient for that study or for the pooled analysis overall. This is 
due to the use of log-transformed exposure metrics, which ensured that 
any multiplicative bias in exposure would have virtually no effect on 
conditional logistic regression coefficients (Document ID 0469, p. 17). 
That is, for this model, a systematic error in exposure estimation for 
any study had little effect on the lung cancer response rate for either 
the specific study or the pooled analysis overall.
ii. Silicosis Mortality
    Following the procedures described above for the lung cancer 
analysis, Toxachemica, Inc. (2004, Document ID 0469) combined both 
sources of random measurement error in a Monte Carlo analysis of the 
silicosis mortality data from Mannetje et al. (2002b, Document ID 
1089). Categorical analyses were performed with a nested case control 
model, in contrast to the Poisson model used previously by Mannetje et 
al. (2002b, Document ID 1089). The nested case control model was 
expected to control more effectively for age. This model yielded 
categorical rate ratio results using the original data (prior to 
simulation of measurement error) which were approximately 20-25 percent 
lower than those reported by Mannetje et al. (2002b, Document ID 1089). 
The silicosis mortality dataset thus appeared to be more sensitive to 
possible error in exposure measurement than the lung cancer dataset, 
for which the mean of the simulation coefficients was virtually 
identical to the original. OSHA notes that its risk estimates derived 
from the pooled analysis (Mannetje et al., 2002b, Document ID 1089), 
incorporated ToxaChemica, Inc.'s simulated measurement error (2004, 
Document ID 0469). More information is provided in the Preliminary QRA 
(Document ID 1711, pp. 310-314).
d. Renal Disease Mortality
i. Exposure-Response Studies
    Steenland et al. (2002a, Document ID 0448) examined renal disease 
mortality in a pooled analysis of three cohorts, as discussed 
previously. These cohorts were chosen because data were available for 
both underlying cause mortality and multiple cause mortality. The 
combined cohort for the pooled analysis (Steenland et al., 2002a, 
Document ID 0448) consisted of 13,382 workers with exposure information 
available for 12,783 (95 percent). SMRs (compared to the U.S. 
population) for renal disease (acute and chronic glomerulonephritis, 
nephrotic syndrome, acute and chronic renal failure, renal sclerosis, 
and nephritis/nephropathy) were statistically significantly elevated 
using multiple cause data (SMR 1.29, 95% CI 1.10-1.47, 193 deaths) and 
underlying cause data (SMR 1.41, 95% CI 1.05-1.85, 51 observed deaths).
ii. Risk Estimates
    As detailed in the Preliminary QRA, OSHA estimated that exposure to 
the previous (100 [mu]g/m\3\) and revised (50 [mu]g/m\3\) general 
industry PELs, over a 45-year working life, would result in a lifetime 
excess renal disease mortality risk of 39 and 32 deaths per 1,000 
workers, respectively. For exposure to the previous construction/
shipyard PELs, OSHA estimated the lifetime excess risk to range from 52 
to 63 deaths per 1,000 workers at exposures of 250 and 500 [mu]g/m\3\, 
respectively. These risks reflect the 1998 background all-cause 
mortality and renal mortality rates for U.S. males. Background rates 
were not adjusted for the renal disease risk estimates because the CDC 
significantly changed the classification of renal diseases after 1998; 
they are now inconsistent with those used by Steenland et al. (2002a, 
Document ID 0448) to ascertain the cause of death of workers in their 
study.
e. Silicosis Morbidity
i. Exposure-Response Studies
    OSHA summarized, in its Preliminary QRA, the principal cross-
sectional and cohort studies that quantitatively characterized 
relationships between exposure to crystalline silica and the 
development of radiographic evidence of silicosis (Document ID 1711). 
Each of these studies relied on estimates of cumulative exposure to 
evaluate the relationship between exposure and silicosis prevalence. 
The health endpoint of interest in these studies was the appearance of 
opacities on chest radiographs indicative of pulmonary fibrosis. Most 
of the studies reviewed by OSHA considered a finding consistent with an 
ILO classification of 1/1 to be a positive diagnosis of silicosis, 
although some also considered an x-ray classification of 1/0 or 0/1 to 
be positive. OSHA noted its belief, in the Preliminary QRA, that the 
most reliable estimates of silicosis morbidity, as detected by chest 
radiographs, come from the studies that evaluated radiographs over 
time, included radiographic evaluation of workers after they left 
employment, and derived cumulative or lifetime estimates of silicosis 
disease risk. OSHA also pointed out that the low sensitivity of chest 
radiography in detecting silicosis suggests that risk estimates derived 
from radiographic evidence likely underestimate the true risk.
    Hnizdo and Sluis-Cremer (1993, Document ID 1052) described the 
results of a retrospective cohort study of 2,235 white gold miners in 
South Africa. A total of 313 miners had developed silicosis (x-ray with 
ILO 1/1 or greater) and had been exposed for an average of 27 years at 
the time of diagnosis. The average latency for the cohort was 35 years 
(range of 18-50 years) from the start of exposure to diagnosis. The 
average respirable dust exposure for the cohort overall was 290 [mu]g/
m\3\ (range 110-470), corresponding to an estimated average respirable 
silica concentration of 90 [mu]g/m\3\ (range 33-140). The average 
cumulative dust exposure for the overall cohort was 6.6 mg/m\3\-yrs 
(range 1.2-18.7). Silicosis risk increased exponentially with 
cumulative exposure to respirable dust in models using log-logistic 
regression. Using the exposure-response relationship developed by 
Hnizdo and Sluis-Cremer (1993, Document ID 1052), and assuming a quartz 
content of 30 percent in respirable dust, Rice and Stayner (1995, 
Document ID 0418) estimated the risk of silicosis to be 13 percent for 
a 45-year exposure to 50 [mu]g/m\3\ respirable crystalline silica.

[[Page 16316]]

    Steenland and Brown (1995b, Document ID 0451) studied 3,330 South 
Dakota gold miners who had worked at least a year underground between 
1940 and 1965. Chest x-rays were obtained in cross-sectional surveys in 
1960 and 1976 and used along with death certificates to ascertain cases 
of silicosis; 128 cases were found via death certificate, 29 were found 
by x-ray (defined as ILO 1/1 or greater), and 13 were found by both. 
OSHA notes that the inclusion of death certificate diagnoses 
complicates interpretation of the risk estimate from this study since, 
as noted by Finkelstein (2000, Document ID 1015), it is not known how 
well such diagnoses correlate with ILO radiographic interpretations; as 
such, the risk estimates derived from this study may not be directly 
comparable to others that rely exclusively on radiographic findings to 
evaluate silicosis morbidity risk. The mean exposure concentration was 
50 [mu]g/m\3\ for the overall cohort, with those hired before 1930 
exposed to an average of 150 [mu]g/m\3\. The average duration of 
exposure for workers with silicosis was 20 years (s.d. = 8.7) compared 
to 8.2 years (s.d. = 7.9) for the rest of the cohort. This study found 
that cumulative exposure was the best disease predictor, followed by 
duration of exposure and average exposure. Lifetime risks were 
estimated from Poisson regression models using standard life table 
techniques; the results indicated an estimated risk of 47 percent 
associated with 45 years of exposure to 90 [mu]g/m\3\ respirable 
crystalline silica, which reduced to 35 percent after adjustment for 
age and calendar time.
    OSHA used the same life table approach as described for estimating 
lung cancer and NMRD mortality risks to estimate lifetime silicosis 
risk based on the silicosis rates, adjusted for age and calendar time, 
calculated by Steenland and Brown (1995b, Table 2, Document ID 0451). 
Silicosis risk was estimated through age 85, assuming exposure from age 
20 through 65, and assuming that the silicosis rate remains constant 
after age 65. All-cause mortality rates to all males for calendar year 
2006 were used to account for background competing risk. From this 
analysis, OSHA estimated the risk from exposure to the previous general 
industry PEL of 100 [mu]g/m\3\ to be 43 percent; this is somewhat 
higher than estimated by Steenland and Brown (1995b) because of the use 
by OSHA of more recent mortality data and calculation of risk through 
age 85 rather than 75. For exposure to the revised PEL of 50 [mu]g/
m\3\, OSHA estimated the lifetime risk to be 7 percent. Since the time 
of the original analysis, NCHS has released updated all-cause mortality 
background rates from 2011; OSHA's final risk estimates, which 
incorporate these updated rates, are available in Section VI, Final 
Quantitative Risk Assessment and Significance of Risk.
    Miller et al. (1995, Document ID 1097; 1998, 0374) and Buchanan et 
al. (2003, Document ID 0306) reported on a follow-up study conducted in 
1990 and 1991 of 547 survivors of a 1,416 member cohort of Scottish 
coal workers from a single mine. These men all worked in the mine 
during a period between early 1971 and mid-1976, during which they had 
experienced ``unusually high concentrations of freshly cut quartz in 
mixed coalmine dust'' (Document ID 0374, p.52). Thus, this cohort 
allowed for the study of exposure-rate effects on the development of 
silicosis. The men all had radiographs dating from before, during, or 
just after this high concentration period, and the 547 participating 
survivors received follow-up chest x-rays between November 1990 and 
April 1991.
    Buchanan et al. (2003, Document ID 0306) presented logistic 
regression models in stages. In the first stage they compared the 
effect of pre- vs. post-1964 cumulative quartz exposures on odds 
ratios; this yielded a statistically significant odds ratio estimate 
for post-1964 exposures. In the second stage they added total dust 
levels both pre- and post-1964, age, smoking status, and the number of 
hours worked pre-1954; only post-1964 cumulative exposures remained 
significant. Finally, in the third stage, they started with only the 
statistically significant post-1964 cumulative exposures, and separated 
these exposures into two quartz bands, one for exposure to 
concentrations less than 2,000 [mu]g/m\3\ respirable quartz and the 
other for concentrations greater than or equal to 2,000 [mu]g/m\3\. 
Both concentration bands were highly statistically significant in the 
presence of the other, with the coefficient for exposure concentrations 
greater than or equal to 2000 [mu]g/m\3\ being three times that of the 
coefficient for concentrations less than 2000 [mu]g/m\3\. From this, 
the authors concluded that their analysis showed that ``the risks of 
silicosis over a working lifetime can rise dramatically with exposure 
to such high concentrations over a timescale of merely a few months'' 
(Buchanan et al. 2003, Document ID 0306, p. 163). The authors then used 
the model to estimate the risk of acquiring a chest x-ray classified as 
ILO category 2/1+, 15 years after exposure, as a function of both low 
(<2000 [mu]g/m\3\) and high (>2000 [mu]g/m\3\) quartz concentrations. 
OSHA chose to use this model to estimate the risk of radiological 
silicosis consistent with an ILO category 2/1+ chest x-ray for several 
exposure scenarios; in each, it assumed 45 years of exposure, 2000 
hours/year of exposure, and no exposure above a concentration of 2000 
[mu]g/m\3\. The results showed that occupational exposures to the 
revised PEL of 50 [mu]g/m\3\ led to an estimated risk of 55 cases per 
1,000 workers. Exposure at the previous general industry PEL of 100 
[mu]g/m\3\ increased the estimate to 301 cases per 1,000 workers. At 
higher exposure levels the risk estimates rose quickly to near 
certainty.
    Chen et al. (2001, Document ID 0332) reported the results of a 
retrospective study of a Chinese cohort of 3,010 underground miners who 
had worked in tin mines at least one year between 1960 and 1965. They 
were followed through 1994, by which time 2,426 (80.6 percent) workers 
had either retired or died, and only 400 (13.3 percent) remained 
employed at the mines. Annual radiographs were taken beginning in 1963 
and cohort members continued to have chest x-rays taken every 2 or 3 
years after leaving work. Silicosis was diagnosed when at least 2 of 3 
radiologists classified a radiograph as being a suspected case or at 
Stage I, II, or III under the 1986 Chinese pneumoconiosis roentgen 
diagnostic criteria, which the authors reported agreed closely with ILO 
categories 0/1, Category 1, Category 2, and Category 3, respectively. 
Silicosis was observed in 33.7 percent of the group; 67.4 percent of 
the cases developed after exposure ended.
    Chen et al. (2001, Document ID 0332) found that a Weibull model 
provided the best fit to relate cumulative silicosis risk to eight 
categories of cumulative total dust exposure. The risk of silicosis was 
strongly related to cumulative silica exposure. The investigators 
predicted a 55-percent risk of silicosis associated with 45 years of 
exposure to 100 [mu]g/m\3\. The paper did not report the risk 
associated with a 45-year exposure to 50 [mu]g/m\3\, but OSHA estimated 
the risk to be about 17 percent (based on the parameters of the Weibull 
model).
    In a later study, Chen et al. (2005, Document ID 0985) investigated 
silicosis morbidity risks among three cohorts to determine if the risk 
varied among workers exposed to silica dust having different 
characteristics. The cohorts consisted of 4,547 pottery workers, 4,028 
tin miners, and 14,427 tungsten miners, all employed after January 1, 
1950 and selected from a total of 20 workplaces. The approximate

[[Page 16317]]

mean cumulative exposures to respirable silica for pottery, tin, and 
tungsten workers were 6.4 mg/m\3\-yrs, 2.4 mg/m\3\-yrs, and 3.2 mg/
m\3\-yrs, respectively. Measurement of particle surface occlusion 
(presence of a mineral coating that may affect the biological 
availability of the quartz component) indicated that, on average, 45 
percent of the surface area of respirable particles collected from 
pottery factory samples was occluded, compared to 18 percent of the 
particle surface area for tin mine samples and 13 percent of particle 
surface area for tungsten mines. When cumulative silica exposure was 
adjusted to reflect exposure to surface-active quartz particles (i.e., 
not occluded), the estimated cumulative risk among pottery workers more 
closely approximated those of the tin and tungsten miners, suggesting 
to the authors that alumino silicate occlusion of the crystalline 
particles in pottery factories at least partially explained the lower 
risk seen among pottery workers, despite their having been more heavily 
exposed. Based on Chen et al. (2005, Document ID 0985), OSHA estimated 
the cumulative silicosis risk associated with 45 years of exposure to 
100 [mu]g/m\3\ respirable crystalline silica to be 6 percent for 
pottery workers, 12 percent for tungsten miners, and 40 percent for tin 
miners. For 45 years of exposure to 50 [mu]g/m\3\, cumulative silicosis 
morbidity risks were estimated to be 2 percent for pottery workers, 2 
percent for tungsten miners, and 10 percent for tin miners.

ii. Risk Estimates

    OSHA's risk estimates for silicosis morbidity ranged between 60 and 
773 per 1,000 workers for a 45-year exposure to the previous general 
industry PEL of 100 [mu]g/m\3\, and between 20 and 170 per 1,000 
workers for a 45-year exposure to the revised PEL of 50 [mu]g/m\3\, 
depending upon the study used. OSHA recognizes that actual risk, to the 
extent that workers are exposed for less than 45 years or 
intermittently, is likely to be lower, but also recognizes that 
silicosis can progress for years after exposure ends. Also, given the 
consistent finding of a monotonic exposure-response relationship for 
silicosis morbidity with cumulative exposure in the studies reviewed, 
OSHA continues to find that cumulative exposure is a reasonable 
exposure metric upon which to base risk estimates in the exposure range 
of interest.

D. Comments and Responses Concerning Silicosis and Non-Malignant 
Respiratory Disease Mortality and Morbidity

    In this section, OSHA focuses on comments pertaining to the 
literature used by the Agency to assess risk for silicosis and non-
malignant respiratory disease (NMRD) mortality and morbidity. As 
discussed in the Review of Health Effects Literature and Preliminary 
QRA (Document ID 1711) and in Section V.C, Summary of the Review of 
Health Effects Literature and Preliminary QRA, of this preamble, OSHA 
used two studies (ToxaChemica, 2004, Document ID 0469; Park et al., 
2002, 0405) to determine lifetime risk for silicosis and NMRD mortality 
and five studies (Buchanan et al., 2003, Document ID 0306; Chen et al., 
2001, 0332; Chen et al., 2005, 0985; Hnizdo and Sluis-Cremer, 1993, 
1052; and Steenland and Brown, 1995b, 0451) to determine cumulative 
risk for silicosis morbidity. OSHA discussed the reasons for selecting 
these scientific studies for quantitative risk assessment in its Review 
of Health Effects Literature and Preliminary QRA (Document ID 1711, pp. 
340-342). Briefly, OSHA concluded that the aforementioned studies used 
scientifically accepted techniques to measure silica exposures and 
health effects in order to determine exposure-response relationships. 
The Agency believed, and continues to believe, that these studies, as a 
group, provide the best available evidence of the exposure-response 
relationships between silica exposure and silicosis morbidity, 
silicosis mortality, and NMRD mortality and that they constitute a 
solid and reliable foundation for OSHA's final risk assessment.
    OSHA received both supportive and critical comments and testimony 
regarding these studies. Comments largely focused on how the authors of 
these studies analyzed their data, and concerns expressed by commenters 
generally focused on exposure levels and measurement, potential biases, 
confounding, statistical significance of study results, and model 
forms. This section does not include extensive discussion on exposure 
measurement error, potential biases, thresholds, confounding factors, 
and the use of the cumulative exposure metric, which are discussed in 
depth in other sections of this preamble, including V.J Comments and 
Responses Concerning Biases in Key Studies and V.K Comments and 
Responses Concerning Exposure Estimation Error and ToxaChemica's 
Uncertainty Analysis. OSHA addresses comments on general model form and 
various other issues here and concludes that these comments do not 
meaningfully affect OSHA's reliance on the studies discussed herein or 
the results of the Agency's final risk assessment.
1. Silicosis and NMRD Mortality
    There are two published studies that report quantitative risk 
assessments of silicosis and NMRD mortality (see Document ID 1711, pp. 
292-298). The first is an exposure-response analysis of diatomaceous 
earth (DE) workers (Park et al., 2002, Document ID 0405). Park et al. 
quantified the relationship between cristobalite exposure and mortality 
caused by NMRD, which includes silicosis, pneumoconiosis, emphysema, 
and chronic bronchitis (Park et al. refers to these conditions as 
``lung disease other than cancer (LDOC),'' while OSHA uses the term 
``NMRD''). Because NMRD captures much of the silicosis 
misclassification that results in underestimation of the disease and 
includes risks from other lung diseases associated with crystalline 
silica exposures, OSHA believes the risk estimates derived from the 
Park et al. study reasonably reflect the risk of death from silica-
related respiratory diseases, including silicosis (Document ID 1711, 
pp. 297-298). The second study (Mannetje et al. 2002b, Document ID 
1089) is a pooled analysis of six epidemiological studies that were 
part of an IARC effort. OSHA's contractor ToxaChemica later conducted a 
reanalysis and uncertainty analysis using these data (ToxaChemica, 
2004, Document ID 0469). OSHA believes that the estimates from the 
pooled study represent credible estimates of mortality risk from 
silicosis across a range of industrial workplaces, but are likely to 
understate the actual risk because silicosis is under-reported as a 
cause of death.
a. Park et al. (2002)
    The American Chemistry Council (ACC) submitted several comments 
pertaining to the Park et al. (2002, Document ID 0405) study, including 
comments on the cohort's exposure concentrations. In its post-hearing 
brief, the ACC noted that the mean crystalline silica exposure in 
Park's DE cohort was estimated to be more than three times the former 
general industry PEL of 100 [mu]g/m\3\ and the mean estimated exposure 
of the workers with silicosis could have been close to 10 times that 
level. According to the ACC, extrapolating risks from the high exposure 
levels in this cohort to the much lower levels relevant to OSHA's risk 
assessment (the previous general industry PEL of 100

[[Page 16318]]

[mu]g/m\3\ and the revised PEL of 50 [mu]g/m\3\) is ``fraught with 
uncertainty'' (Document ID 4209, pp. 84-85).
    OSHA acknowledges that there is some uncertainty in using models 
heavily influenced by exposures above the previous PEL due to potential 
deviance at areas of the relationship with fewer data points. However, 
OSHA believes that the ACC's characterization of exposures in the Park 
et al. (2002) study as vastly higher than the final and former PELs is 
incorrect. The ACC focused on mean exposure concentrations, reported by 
Park et al. as 290 [mu]g/m\3\, to make this argument (Document ID 0405, 
p. 37). However, in the Park et al. study, the mean cumulative exposure 
of the cohort was 2.16 mg/m\3\-yrs, lower than what the final rule 
would permit over 45 years of exposure (2.25 mg/m\3\-yrs) (Document ID 
0405, p. 37). Thus, whereas some participants in the Park et al. study 
had higher average-8-hour exposures than were typical under the 
previous PEL, they were quite comparable to the exposures workers might 
accumulate over their working lives under the final PEL of 50 [mu]g/
m\3\. In addition, as discussed in Section V.M, Comments and Responses 
Concerning Working Life, Life Tables, and Dose Metric, OSHA believes 
that the evidence in the rulemaking record, including comments and 
testimony from NIOSH (Document ID 3579, Tr. 127), Kyle Steenland, Ph.D. 
(Document ID 3580, Tr. 1227), and OSHA peer reviewer Kenneth Crump, 
Ph.D. (Document ID 1716, p. 166), points to cumulative exposure as a 
reasonable and appropriate dose metric for deriving exposure-response 
relationships. In sum, OSHA does not agree that the Park study should 
be discounted based on the ACC's concerns about the estimated exposure 
concentrations in the diatomaceous earth cohort.
    The ACC also criticized the Park study for its treatment of 
possible confounding by smoking and exposure to asbestos. The ACC 
commented in its pre-hearing brief that data on smoking was available 
for only half of the cohort (Document ID 2307, Attachment A, p. 108). 
The Panel also wrote that, ``while Park et al. dismissed asbestos as a 
potential confounder and omitted asbestos exposure in their final 
models, the situation is not as clear-cut as they would have one 
believe'' (Document ID 2307, Attachment A, p. 109). The Panel 
highlighted that Checkoway et al. (1997), the study upon which Park 
relied to dismiss asbestos as a potential confounder, noted that 
``misclassification of asbestos exposure may have hindered our ability 
to control for asbestos as a potential confounder'' (Document ID 0326, 
p. 685; 2307, Attachment A, p. 109).
    OSHA has reviewed the ACC's concerns, and maintains that Park et 
al. adequately addressed the issues of possible confounding by smoking 
and exposure to asbestos in this data set. Smoking habits of a third of 
the individuals who died from NMRD were known in the Park et al. (2002) 
study. Based on that partial knowledge of smoking habits, Park et al. 
presented analyses indicating that confounding by smoking was unlikely 
to significantly impact the observed relationship between cumulative 
exposure to crystalline silica and NMRD mortality (Document ID 0405, p. 
41). Specifically, Park et al. (2002) performed internally standardized 
analyses, which tend to be less susceptible to confounding by smoking 
since they compare the mortality experience of groups of workers within 
the cohort rather than comparing the mortality experience of the cohort 
with an external population (such as by using national mortality 
rates); the authors found that the internally standardized models 
yielded only slightly lower exposure-response coefficients than 
externally adjusted models (Document ID 0405; 1711, p. 302). These 
results suggested that estimates of NMRD mortality risks based on this 
cohort are not likely to be exaggerated due to cohort members' smoking 
habits. Park et al. also stated that the authors' findings regarding 
possible confounding by smoking were consistent with those of Checkoway 
et al., who also concluded there it was ``very unlikely'' that smoking 
could explain the association between mortality from NMRD and silica 
exposure in this cohort (Document ID 0405, p. 41; 0326, p. 687). NIOSH 
noted that ``[r]esidual confounding from poorly characterized smoking 
could have an effect,'' but that effect could be either positive or 
negative (Document ID 4233, pp. 32-33). While OSHA agrees that 
comprehensive smoking data would be ideal, the Agency believes that the 
approach taken by Park et al. to address this issue was reasonable.
    Asbestos exposure was estimated for all workers in Park et al., 
which enabled the researchers to directly test confounding. They 
``found no confounding by asbestos'' and, accordingly, omitted asbestos 
exposure in their final modeling (Document ID 0405, p. 41). As 
discussed in the Review of Health Effects Literature and Preliminary 
QRA (Document ID 1711, pp. 301-302), exposure to asbestos was 
particularly prevalent among workers employed prior to 1930; after 
1930, asbestos was presumably no longer used in the process (Gibbs, 
1998, Document ID 1024, p. 307; Checkoway et al., 1998, 0984, p. 309). 
Checkoway et al. (1998), who evaluated the issue of asbestos 
confounding for the same cohort used by Park et al., found that the 
risk ratio for the highest silica exposure group after excluding the 
workers employed before 1930 from the cohort (Relative Risk (RR) = 
1.73) was almost identical to the risk ratio of the high-exposure group 
before excluding those same workers (RR = 1.74) (Document ID 0984, p. 
309). In addition, Checkoway's reanalysis of the original cohort study 
(Checkoway et al., 1993) examined those members of the cohort for whom 
there was quantitative information on asbestos exposure, based on a 
mixture of historical exposure monitoring data, production records, and 
recorded quantities of asbestos included in mixed products of the plant 
(Checkoway et al., 1996, Document ID 0325). The authors found an 
increasing trend in lung cancer mortality with exposure to crystalline 
silica after controlling for asbestos exposure and found only minor 
changes in relative risk estimates after adjusting for asbestos 
exposure (1996, Document ID 0325). Finally, Checkoway et al. (1998) 
reported that the prevalence of pleural abnormalities (indicators of 
asbestos exposure) among workers hired before 1930 (4.2 percent) was 
similar to that of workers hired after 1930 who presumably had no 
asbestos exposure (4.9 percent), suggesting that asbestos exposure was 
not a confounder for lung abnormalities in this group of workers 
(Document ID 0984, p. 309). Therefore, Checkoway et al. (1998) 
concluded that asbestos was not likely to significantly confound the 
exposure-response relationship observed between lung cancer mortality 
and exposure to crystalline silica in diatomaceous earth workers.
    Rice et al. also utilized Checkoway's (1997, Document ID 0326) data 
to test for confounding by asbestos in their Poisson and Cox 
proportional hazards models. Finding no evidence of confounding, Rice 
et al. did not include asbestos exposure as a variable in the final 
models presented in their 2001 paper (Document ID 1118, p. 41). Based 
on these numerous assessments of the effects of exposure to asbestos in 
the diatomaceous earth workers cohort used by Park et al. (2002), OSHA 
concludes that concerns about asbestos confounding in this cohort have 
been adequately addressed and that the additional analyses performed by 
Park et al. on this issue confirmed the findings of prior researchers 
that

[[Page 16319]]

confounding by asbestos exposure was not likely to have a large effect 
on exposure-response relationships.
    The ACC also expressed concern about model selection. Louis Anthony 
Cox, Jr., Ph.D., of Cox Associates, on behalf of the ACC, was concerned 
that the linear relative rate model was not appropriate because it is 
not designed to test for exposure-response thresholds and, similarly, 
the ACC has argued that threshold models are appropriate for 
crystalline silica-related diseases (Document ID 2307, Attachment 4, 
pp. 91). The ACC claimed that the Park et al. (2002) study is ``fully 
consistent'' with a threshold above the 100 [mu]g/m\3\ concentration 
for NMRD, including silicosis, mortality (Document ID 2307, Attachment 
A, p. 107).
    In its post-hearing comments, NIOSH explained that categorical 
analysis for NMRD indicated no threshold existed with cumulative 
exposure corresponding to 25 [mu]g/m\3\ over 40 years of exposure, 
which is below the cumulative exposure equivalent to the new PEL over 
45 years (Document ID 4233, p. 27). Park et al. did not estimate a 
threshold below that level because the data lacked the power needed to 
discern a threshold (Document ID 4233, p. 27). OSHA agrees with NIOSH's 
assessment. In addition, as discussed extensively in Section V.I, 
Comments and Responses Concerning Thresholds for Silica-Related 
Diseases, OSHA has carefully reviewed the issue of thresholds and has 
concluded, based on the best available evidence, that workers with 
cumulative and average exposure levels permitted under the previous PEL 
of 100 [mu]g/m\3\ are at risk of silica-related disease (that is, there 
is unlikely to be an exposure-response threshold at or near 100 [mu]g/
m\3\). For these reasons, OSHA disagrees with Dr. Cox's criticism of 
Park et al.'s reliance on the linear relative rate model.
    The ACC then questioned the use of unlagged cumulative exposures as 
the metric in Park et al. (2002). Dr. Cox noted that ``[u]nlagged 
models are not very biologically plausible for dust-related NMRD deaths 
(if any) caused by exposure concentrations in the range of interest. 
Unresolved chronic inflammation and degradation of lung defenses takes 
years to decades to manifest'' (Document ID 2307, Attachment 4, p. 92). 
OSHA considers this criticism overstated. Park et al. considered a 
range of lag periods, from two years to 15. They found that 
``[u]nlagged models seemed to provide the best fit to the data in 
Poisson analyses although lagged models performed almost as well'' 
(Document ID 0405, p. 37). Based on those findings, as well as 
acknowledgments that NMRD effects other than silicosis (e.g., chronic 
bronchitis) may be observable without a relatively long lag time 
(unlike cancer) and that the majority of deaths observed in the cohort 
were indeed NMRD other than silicosis, the researchers decided to use 
an unlagged model. Because Park found the differences between the 
lagged and unlagged models for this cohort and the NMRD endpoint to be 
insignificant, OSHA finds that Park's final choice to use an unlagged 
model does not detract from OSHA's decision to utilize lagged models in 
its risk assessment.
    The ACC was also concerned about the truncation of cumulative 
exposures in the Park et al. (2002) paper. Peter Morfeld, Dr. rer. 
medic, stated that Park et al.:

suffers from a methodological drawback. . . . The authors truncated 
the cumulative RCS dust exposures before doing the final analyses 
based on their observation of where the cases were found. The 
maximum in the study was 62.5 mg/m\3\-years but exposures were only 
used up to 32 mg/m\3\-years because no LDOC deaths occurred at 
exposures higher than that level. Such a selection distorts the 
estimated exposure-response relationship because it is based on the 
outcome of the study and on the exposure variable. Because high 
exposures with no effects were deliberately ignored, the exposure-
response effect estimates are biased upward (Document ID 2307, 
Attachment 2, p. 27).

    OSHA acknowledges this concern about the truncation of data in the 
study, and asked Mr. Park about it at the public hearing. Mr. Park 
testified that there were good reasons to truncate the part of the 
exposed workforce at the high end of cumulative exposure. He noted 
several plausible reasons for the drop-off in the number of cases at 
high exposures (attenuation), including random variance in 
susceptibility to disease among different people and the healthy worker 
survivor effect \6\ (Document ID 3579, Tr. 242-243). He also stated 
that this attenuation is a common occurrence in studies of workers 
(Document ID 3579, Tr. 242). Mr. Park then emphasized that how one 
describes the higher end of the exposure-response relationship is 
inconsequential for the risk assessment process because the 
relationship at the lower end of the spectrum, where the PEL was 
determined, is more important for rulemaking (Document ID 3579, Tr. 
242-243). He also stated, in a post-hearing comment, that ``[f]or the 
purpose of low exposure extrapolation, adding a quadratic term [to 
better describe the entirety of the exposure-response relationship] 
would result in loss of precision with no advantage [gained] over 
truncation of high cumulative exposure observation time'' (Document ID 
4233, p. 26). To summarize, Mr. Park stated that there are good 
scientific reasons to expect attenuation of exposure-response at the 
high end of the cumulative exposure range and that use of higher-
exposure data affected by healthy worker survivor effect or other 
issues could reduce precision of the exposure-response model at the 
lower exposures that are more relevant to the final silica standard. 
OSHA finds that Mr. Park's approach in his study, along with his 
explanations in the rulemaking record, are reasonable and that he has 
fully responded to the concerns of the ACC.
---------------------------------------------------------------------------

    \6\ Briefly, if individuals cease working due to illness, then 
those individuals will not be represented in cohort subgroups having 
the highest cumulative exposures. That exclusion may enable 
individuals with greater physiological resilience to silica 
exposures to be overrepresented in cohorts exposed to greater 
amounts of silica. Further discussion on the healthy worker survivor 
effect can be found in Section V.F, Comments and Responses on Lung 
Cancer Mortality.
---------------------------------------------------------------------------

    Dr. Morfeld also noted that alternative techniques that do not 
require truncation are available to account for a healthy worker 
survivor effect (Document ID 2307, Attachment 2, pp. 27-28). OSHA 
believes such techniques, such as g-estimation, to be relatively new or 
not yet in standard use in occupational epidemiology. As discussed 
above, OSHA finds Mr. Park's approach in his study to be reasonable.
    Finally, Dr. Cox stated in his comments that:

key studies relied on by OSHA, such as Park et al. (2002), do not 
correct for biases in reported ER [exposure-response] relations due 
to residual confounding by age (within age categories), i.e., the 
fact that older workers may tend to have both higher lung cancer 
risks and higher values of occupational exposure metrics, even if 
one does not cause the other. This can induce a non-causal 
association between the occupational exposure metrics and the risk 
of cancer (Document ID 2307, Attachment 4, p. 29).

    Confounding occurs in an epidemiological study when the 
contribution of a causal factor cannot be separated from the effect of 
another variable (e.g., age) not accounted for in the analysis. 
Residual confounding occurs when attempts to control for confounding 
are not precise enough (e.g., controlling for age by using groups with 
age spans that are too wide), or subjects are misclassified with 
respect to confounders (Document ID 3607, p. 1). However, the Park et 
al. (2002) study of non-malignant respiratory disease mortality, which 
Dr. Cox cited as not

[[Page 16320]]

considering residual confounding by age, actually addressed this issue 
by using 13 five-year age groups (<25, 25-29, 30-34, etc.) in the 
models (Document ID 0405, p. 37). Further discussion on residual 
confounding bias is found in Section V.J, Comments and Responses 
Concerning Biases in Key Studies.
    The inclusion of Park et al. (2002) (Document ID 0405) in OSHA's 
risk assessment has additional support in the record. OSHA's expert 
peer-review panel supported including the Park et al. study in the risk 
assessment, with Gary Ginsberg, Ph.D., stating that it ``represents a 
reasonable estimate of silica-induced total respiratory mortality'' 
(Document ID 3574, p. 29). In addition, as OSHA noted in its Review of 
Health Effects Literature and Preliminary QRA (Document ID 1711, pp. 
355-356), the Park et al. study is complemented by the Mannetje et al. 
multi-cohort silicosis mortality pooled study, which included several 
cohorts that had exposure concentrations in the range of interest for 
this rulemaking and also showed clear evidence of significant risk of 
silicosis and other NMRD at the previous general industry and 
construction PELs (2002b, Document ID 1089).
b. Mannetje et al. (2002b) and ToxaChemica (2004)
    The ACC also submitted several comments on the Mannetje et al. 
(2002b) study of silicosis mortality; the data from Mannetje et al. 
were used in the ToxaChemica (2004) re-analysis. As noted above, the 
Mannetje et al. (2002b) study was a pooled analysis of silicosis 
mortality data from six epidemiological cohorts. This study showed a 
statistically significant association between silicosis mortality and 
workers' cumulative exposure, as well as with average exposure and 
exposure duration. The ACC's pre-hearing brief stated that the study 
``provided no justification for the relative rate model forms [Mannetje 
et al.] used to evaluate exposure-response'' (Document ID 2307, 
Attachment A, p. 113). The concern expressed was that the study may not 
have considered all potential exposure-response relationships and was 
unable to discern differences between monotonic and non-monotonic 
characteristics (Document ID 2307, Attachment A, p. 113-114).
    Mannetje et al. (2002b, Document ID 1089) did not discuss whether 
models other than relative rate models were tested. However, Mannetje's 
data was reexamined by ToxaChemica, Inc. on request from OSHA and the 
reexamined data was used by OSHA to help estimate lifetime risk for 
silicosis mortality (2004, Document ID 0469; 1711, pp. 310-314). The 
ToxaChemica reanalysis of the data included a categorical analysis and 
a five-knot restricted spline analysis, in addition to a logistic 
model, using the log of cumulative exposure (Document ID 0469, p. 50). 
ToxaChemica also corrected some errors found in the original data set 
and used a nested case-control approach, which they stated would 
control more precisely for age than the Poisson regression approach 
used by Mannetje et al. (Document ID 0469, p. 18). As shown in Figure 5 
of ToxaChemica's report, the restricted spline model (which has 
considerable flexibility to represent non-monotonic features of 
exposure-response data) appeared to be monotonic, while the categorical 
analysis appeared largely monotonic but for one exposure group 
(Document ID 0469, p. 40, 50). When not adjusted for measurement error, 
the second highest exposure group deviated from the monotonic 
relationship existing between the other groups. However, the deviation 
was resolved when two sources of measurement error were accounted for 
(Document ID 0469, p. 40). The categorical analysis, restricted spline 
model, and logistic model yielded roughly similar exposure-response 
curves (Document ID 0469, p. 50). OSHA concludes that the ToxaChemica 
reanalysis addresses the concerns raised by the ACC by finding similar 
exposure-response relationships regardless of the model as well as 
providing greater validation of a monotonic curve.
    The ACC next questioned the odds ratios generated in the Mannetje 
et al. (2002b) study (Document ID 2307, p. 114; 4209, p. 88). The Panel 
noted that ``the exposure-response relationship is not even fully 
monotonic'' and that the silica odds ratios in the pooled analysis have 
overlapping confidence intervals, suggesting no statistically 
significant difference (Document ID 2307, p. 114). The Panel concluded 
that ``the data indicate that there is no clear effect of exposure on 
odds ratios over the entire range considered by the authors; hence, the 
study provides no basis for concluding that reducing exposures will 
reduce the odds ratio for silicosis mortality'' (Document ID 4209, p. 
88). Essentially, the ACC argued that the data do not appear to fit a 
monotonic relationship and that the confidence intervals for each 
exposure level overlap too much to discern any differences in risk 
ratios between those exposures.
    OSHA believes that the ACC overstated its contention about 
confidence interval overlap between groups in the Mannetje et al. 
(2002b) paper. Although the original data set reported in the study 
lacks a monotonic relationship on the upper end of the exposure 
spectrum (>9.58 mg/m\3\-yrs) (possibly due to a healthy worker survivor 
effect, as explained above), OSHA notes that the 95 percent confidence 
intervals reported do not contradict the presence of a monotonic 
relationship (Document ID 1089). First, the confidence intervals of the 
lower exposed groups did not overlap with those of the higher exposed 
groups in that study (Document ID 1089). Second, even if they did, 
overlap in confidence intervals does not mean that there is not a 
significant difference between those groups. While it is true that, if 
95 percent confidence intervals do not overlap, the represented 
populations are statistically significantly different, the converse--
that, if confidence intervals do overlap, there is no statistically 
significant difference--is not always true (Nathaniel Schenker and Jane 
F. Gentleman. ``On Judging the Significance of Differences by Examining 
the Overlap Between Confidence Intervals.'' The American Statistician. 
55(3): 2001. 182-186. (http://www.tandfonline.com/doi/abs/10.1198/000313001317097960).
    Finally, as discussed above and in detail in Section V.K, Comments 
and Responses Concerning Exposure Estimation Error and ToxaChemica's 
Uncertainty Analysis, the ToxaChemica et al. (2004) re-analysis of the 
corrected Mannetje et al. (2002b) data adjusting for two sources of 
measurement error resulted in a monotonic relationship for the risk 
ratios (Document ID 0469).
2. Silicosis Morbidity
    OSHA relied on five studies for determining risk for silicosis 
morbidity: Buchanan et al., 2003 (Document ID 0306), Chen et al., 2001 
(Document ID 0332), Chen et al., 2005 (Document ID 0985), Hnizdo and 
Sluis-Cremer, 1993 (Document ID 1052), and Steenland and Brown, 1995b 
(Document ID 0451). OSHA finds that the most reliable estimates of 
silicosis morbidity, as detected by chest radiographs, come from these 
five studies because they evaluated radiographs over time, included 
post-employment radiographic evaluations, and derived cumulative or 
lifetime estimates of silicosis disease risk. OSHA received several 
comments about these studies.
a. Buchanan et al. (2003)
    Buchanan et al. (2003) reported on a cohort of Scottish coal 
workers (Document ID 0306). The authors found a statistically 
significant relationship

[[Page 16321]]

between silicosis and cumulative exposure acquired after 1964 (Document 
ID 0306). They also found that the risks of silicosis over a working 
lifetime can rise dramatically with exposure to high concentrations 
over a timescale of merely a few months (Document ID 0306). In the 
Preliminary QRA, OSHA considered this study to be of the highest 
overall quality of the studies relied upon to assess silicosis 
morbidity risks, in large measure because the underlying exposure data 
was based on modern exposure measurement methods and avoided the need 
to estimate historical exposures. The risk estimates derived from this 
study were lower than those derived from any of the other studies 
criticized by the ACC. One reason for this is because Buchanan et al. 
only included cases with chest x-ray findings having an ILO score of 2/
1 or higher, whereas the other studies included cases with less damage, 
having a lower degree of perfusion on x-ray (ILO 1/0 or 1/1) (Document 
ID 0306). Thus, OSHA considered the risk estimates derived from the 
Buchanan et al. study to be more likely to understate risks.
    Dr. Cox commented that age needed to be included for modeling in 
Dr. Miller's 1998 paper, the data from which were used in the Buchanan 
et al. (2003) paper (Document ID 2307, Attachment 4, p. 97). However, 
the Miller et al. (1998) study explicitly states that age was one of 
several variables that were tried in the model but did not improve the 
model's fit, as was time spent working in the poorly characterized 
conditions before 1954 (Document ID 0374, p. 57). OSHA concludes that 
the original paper did assess these variables and how they related to 
the exposure-response relationship. Buchanan et al. (2003) also noted 
their own finding that differences in age and exposure both failed to 
improve fit, in agreement with Miller et al.'s conclusion (Document ID 
0306, p. 161). OSHA therefore finds no credible reason that age should 
have been included as a variable in Miller et al. (1998).
    Dr. Cox also questioned the modeling methods in the Buchanan paper, 
which presented logistic regression in progressive stages to search for 
significance (Document ID 2307, Attachment 4, pp. 97-98; 0306, pp. 161-
163). Dr. Cox claimed that this is an example of uncorrected multiple 
testing bias where the post hoc selection of data, variables, and 
models can make independent variables appear to be statistically 
significant in the prediction model. He suggested that corrections for 
bias are needed to determine if the reported significance is causal or 
statistical (Document ID 2307, Attachment 4, pp. 97-98). OSHA peer 
reviewer Brian Miller, Ph.D., stated that Dr. Cox's claim that the 
model was affected by multiple testing bias is unfounded (Document ID 
3574, pp. 31-32). He noted that the model was based on a detailed 
knowledge of the history of exposures at that colliery, and represented 
the researchers' attempt to build ``a reality-driven and `best-fitting' 
model,'' (Document ID 3574, p. 31, quoting 2307, Attachment 4, p. 4). 
Furthermore, none of OSHA's peer reviewers raised any concerns about 
the approach taken by Buchanan et al. to develop their exposure-
response model and none suggested that corrections needed to be made 
for multiple testing bias; all of them supported the study's inclusion 
in OSHA's risk assessment (Document ID 3574). Finally, the cumulative 
risk for silicosis morbidity derived from this study is similar to 
values from other papers reported in the QRA (see OSHA's Final 
Quantitative Risk Assessment in Section VI). Therefore, for the reasons 
discussed above, OSHA is not convinced by Dr. Cox's arguments and finds 
no credible reason to remove Buchanan et al. (2003) from consideration.
b. Chen et al. (2001, 2005), Steenland and Brown (1995), and Hnizdo and 
Sluis-Cremer (1993)
    The ACC also commented on several other studies used by OSHA to 
estimate silicosis morbidity risks; these were the studies by Chen et 
al. (2001, Document ID 0332; 2005, 0985), Steenland and Brown (1995b, 
Document ID 0451), and Hnizdo and Sluis-Cremer (1993, Document ID 
1052). The ACC's comments focus on uncertainties in estimating the 
historical exposures of cohort members (Document ID 2307, Attachment A, 
pp. 117-122, 124-130, 132-136). Section V.K, Comments and Responses 
Concerning Exposure Estimation Error and ToxaChemica's Uncertainty 
Analysis, discusses the record in detail with respect to the general 
issue of uncertainties in estimating historical exposures to respirable 
crystalline silica in epidemiological studies. The issues specific to 
the studies relied upon by OSHA in its risk estimates for silicosis 
morbidity will be discussed below.
    In the Chen et al. studies, which focused on mining (i.e., tin, 
tungsten) and pottery cohorts, high volume area samplers collected dust 
and the respirable crystalline silica concentration was determined from 
those samples (2001, Document ID 0332; 2005, 0985). However, according 
to the ACC, the rest of the collected dust was not assessed for 
chemicals that potentially could also cause radiographic opacities 
(Document ID 2307, Attachment A, pp. 132-135). Neither study expressed 
reason to be concerned about the non-silica portion of the dust 
samples. OSHA recognizes that uncertainty about potential unknown 
exposures exists in retrospective studies, which describes most 
epidemiological research. However, OSHA emphasizes that the risk values 
derived from the Chen et al. studies do not differ remarkably from 
other silicosis morbidity studies used in the risk assessment (Document 
ID 0306, 1052, 0451). Therefore, OSHA concludes that it is unlikely 
that an unknown compound significantly impacted the exposure-response 
relationships reported in both Chen studies.
    The study on gold miners (Steenland and Brown, 1995b, Document ID 
0451), which found that cumulative exposure was the best disease 
predictor, followed by duration of exposure and average exposure, was 
also criticized by the ACC, which alleged that the exposure assessment 
suffered from ``enormous uncertainty'' (Document ID 2307, Attachment A, 
pp. 146-147). The ACC noted that exposure measurements were not 
available for the years prior to 1937 or after 1975 and that this 
limitation of the exposure information may have resulted in an 
underestimation of exposures (Document ID 2307, Attachment A, pp. 124-
126). OSHA agrees that these are potential sources of uncertainty in 
the exposure estimates, but recognizes exposure uncertainty to be a 
common occurrence in occupational epidemiology studies. OSHA believes 
that the authors used the best measurement data available to them in 
their study.
    The ACC also took issue with Steenland and Brown's conversion 
factor for converting particle count to respirable silica mass (10 
mppcf = 100 [mu]g/m\3\), which was somewhat higher than that used in 
the Vermont granite worker studies (10 mppcf = 75 [mu]g/m\3\) (Document 
ID 2307, Attachment A, p. 126). OSHA notes that the study's reasoning 
for adopting that specific particle count conversion factor was to 
address the higher percentage of silica found in the gold mine samples 
applicable to their cohort in comparison to the Vermont granite study 
(Document ID 0451, p. 1373). OSHA finds this decision, which was based 
on the specific known exposure conditions of this cohort, to be 
reasonable.
    With respect to the Hnizdo and Sluis-Cremer (1993, Document ID 
1052)

[[Page 16322]]

study, which found that silicosis risk increased exponentially with 
cumulative exposure to respirable dust (Document ID 1052, p. 447), the 
ACC questioned three assumptions the study made about exposures. First, 
exposures were assumed to be static from the 1930s to the 1960s, based 
on measurements from the late 1950s to mid-1960s, an assumption that, 
according to the ACC, might underestimate exposure for workers employed 
before the late 1950s (Document ID 2307, Attachment A, pp. 117-119). 
Second, although respirable dust, by definition, includes particles up 
to 10 [mu]m, the study only considered particles sized between 0.5 and 
5 [mu]m in diameter (Document ID 1052, p. 449). The ACC contends this 
exclusion may have resulted in underestimated exposure and 
overestimated risk (Document ID 2307, Attachment A, p. 119). OSHA 
agrees that uncertainty in exposure estimates is an important issue in 
the silica risk assessment, and generally discusses the issue of 
exposure measurement uncertainty in depth in a quantitative uncertainty 
analysis described in Section V.K, Comments and Responses Concerning 
Exposure Estimation Error and ToxaChemica's Uncertainty Analysis. As 
discussed there, after accounting for the likely effects of exposure 
measurement uncertainty in the risk assessment, OSHA affirms the 
conclusion of the risk assessment that there is significant risk of 
silicosis to workers exposed at the previous PELs.
    Thirdly, the ACC challenged the authors' estimate of the quartz 
content of the dust as 30 percent when it should have been 54 percent 
(Document ID 1052, p. 450; 2307, Attachment A, p. 120). According to 
the ACC, the 30 percent estimate was based on an incorrect assumption 
that the samples had been acid-washed (resulting in a reduction in 
silica content) before the quartz content was measured (Document ID 
2307, Attachment A, pp. 120-122). This assumption would greatly 
underestimate the exposures of the cohort and the exposures needed to 
cause adverse effects, thus overestimating actual risk (Document ID 
2307, Attachment A, pp. 121-122). The ACC recommended that the quartz 
content in the Hnizdo and Sluis-Cremer study be increased from 30 to 54 
percent, based on the Gibbs and Du Toit study (2002, Document ID 1025, 
p. 602).
    OSHA considered this issue in the Preliminary QRA (Document ID 
1711, p. 332). OSHA noted that the California Environmental Protection 
Agency's Office of Environmental Health Hazard Assessment reviewed the 
source data for Hnizdo and Sluis-Cremer, located in the Page-Shipp and 
Harris (1972, Document ID 0583) study, and compared them to the quartz 
exposures calculated by Hnizdo and Sluis-Cremer (OEHHA, 2005, Document 
ID 1322, p. 29). OEHHA concluded after analyzing the data that the 
samples likely were not acid-washed and that the Hnizdo and Sluis-
Cremer paper erred in describing that aspect of the samples. 
Additionally, OEHHA reported data that suggests that the 30 percent 
quartz concentration may actually overestimate the exposure. It noted 
that recent investigations found the quartz content of respirable dust 
in South African gold mines to be less than 30 percent (Document ID 
1322). In summary, OSHA concludes that no meaningful evidence was 
submitted to the rulemaking record that changes OSHA's original 
decision to include the Hnizdo and Sluis-Cremer study in its risk 
assessment.
    Despite the uncertainties inherent in estimating the exposures of 
occupational cohorts in silicosis morbidity studies, the resulting 
estimates of risk for the previous general industry PEL of 100 [mu]g/
m\3\ are in reasonable agreement and indicate that lifetime risks of 
silicosis morbidity at this level, and, by extension, risks at the 
higher previous PELs for maritime and construction (see section VI, 
Final Quantitative Risk Assessment and Significance of Risk) are in the 
range of hundreds of cases per 1,000 workers. Even in the unlikely 
event that exposure estimates underlying all of these studies were 
systematically understated by several fold, the magnitude of resulting 
risks would likely still be such that OSHA would determine them to be 
significant.
3. Conclusion
    After carefully considering all of the comments on the studies 
relied on by OSHA to estimate silicosis and NMRD mortality and 
silicosis morbidity risks, OSHA concludes that the scientific evidence 
used in its quantitative risk assessment substantially supports the 
Agency's finding of significant risk for silicosis and non-malignant 
respiratory disease. In its risk estimates in the Preliminary QRA, OSHA 
acknowledged the uncertainties raised by the ACC and other commenters, 
but the Agency nevertheless concluded that the assessment was 
sufficient for evaluating the significance of the risk. After 
evaluating the evidence in the record on this topic, OSHA continues to 
conclude that its risk assessment (see Final Quantitative Risk 
Assessment in Section VI.C of this preamble) provides a reasonable and 
well-supported estimate of the risk faced by workers who are exposed to 
respirable crystalline silica.

E. Comments and Responses Concerning Surveillance Data on Silicosis 
Morbidity and Mortality

    As discussed above in this preamble, OSHA has relied on 
epidemiological studies to assess the risk of silicosis, a debilitating 
and potentially fatal occupationally-related lung disease caused by 
exposure to respirable crystalline silica. In the proposed rule (78 FR 
56273, 56298; also Document ID 1711, pp. 31-49), OSHA also discussed 
data from silicosis surveillance programs that provide some information 
about the number of silicosis-associated deaths or the extent of 
silicosis morbidity in the U.S. (78 FR at 56298). However, as OSHA 
explained, the surveillance data are not sufficient for estimating the 
risks of health effects associated with exposure to silica, nor are 
they sufficient for estimating the benefits of any potential regulatory 
action. This is because silicosis-related surveillance data are only 
available from a few states and do not provide exposure data that can 
be matched to surveillance data. Consequently, there is no way of 
knowing how much silica a person was exposed to before developing fatal 
silicosis (78 FR at 56298).
    In addition, the available data likely understate the resulting 
death and disease rates in U.S. workers exposed to crystalline silica 
(78 FR 56298). This understatement is due in large part to: (1) The 
passive nature of these surveillance systems, which rely on healthcare 
providers' awareness of a reporting requirement and submission of the 
appropriate information on standardized forms to health departments; 
(2) the long latency period of silicosis; (3) incomplete occupational 
exposure histories, and (4) other factors that result in a lack of 
recognition of silicosis by healthcare providers, including the low 
sensitivity, or ability of chest x-rays to identify cases of silicosis 
(78 FR 56298). Specific to death certificate data, information on usual 
industry and occupation are available from only 26 states for the 
period 1985 to 1999, and those codes are not verifiable (Document ID 
1711). Added to these limitations is the ``lagging'' nature of 
surveillance data; it often takes years for cases to be reported, 
confirmed, and recorded. Furthermore, in many cases, the available 
surveillance systems lack information about actual exposures or even 
information about the usual occupation or industry of the deceased 
individual, which could provide some information about occupational

[[Page 16323]]

exposure (see 78 FR at 56298). Therefore, the Agency did not use these 
surveillance data to estimate the risk of silicosis for the purpose of 
meeting its legal requirements to prove a significant risk of material 
impairment of health (see 29 U.S.C. 655(b)(5); Benzene, 448 U.S. 607, 
642 (1980)).
    Comments and testimony focusing on the silicosis surveillance data 
alleged that OSHA should have used the surveillance data in its risk 
estimates. Stakeholders argued that the declining numbers of reported 
silicosis deaths prove the lack of necessity for a new silica standard. 
Commenters also claimed that the surveillance data prove that OSHA 
overestimated both the risks at the former permissible exposure limits 
(PELs) and the benefits of the new rule.
    After reviewing the rulemaking record, OSHA maintains its view that 
these silicosis surveillance data, although useful for providing 
context and an illustration of a significant general trend in the 
reduction of deaths associated with silicosis over the past 4-5 
decades, are not sufficient for estimating the magnitude of the risk or 
the expected benefits. In the case of silicosis, surveillance data are 
useful for describing general trends nationally and a few states have 
the ability to use the data at the local or state level to identify 
``sentinel events'' that would justify initiating an inspection of a 
workplace, for example. The overall data, however, are inadequate and 
inappropriate for estimating risks or benefits associated with various 
exposure levels, as is required of OSHA's regulatory process, in part 
because they significantly understate the extent of silicosis in 
workers in the United States and because they lack information about 
exposure levels, exposure sources (e.g., type of job), controls, and 
health effects that is necessary to examine the effects of lowering the 
PEL. Thus, for these reasons and the ones discussed below, OSHA has 
continued to rely on epidemiological data to meet its burden of 
demonstrating that workers exposed to respirable crystalline silica at 
the previous PELs face a significant risk of developing silicosis and 
that risk will be reduced when the new limit is fully implemented. 
Another related concern identified by stakeholders is the apparent 
inconsistency between surveillance data and risk and benefits estimates 
derived from modeling epidemiological data (Document ID 4194, pp. 7-10; 
4209, pp. 3-4). However, this difference is not an inconsistency, but 
the result of comparing two distinctly different items. Surveillance 
data, primarily death certificate data, are known to be under-reported 
and lack associated exposure data necessary to model relationships 
between various exposure levels and observance of health effects. For 
these reasons, OSHA relied on epidemiologic studies with detailed 
exposure-response relationships to evaluate the significance of risk at 
the preceding and new PELs. Thus, the silicosis mortality data derived 
from death certificates and estimates of silica-related mortality risks 
derived from well-conducted epidemiologic studies cannot be directly 
compared in any meaningful way. With respect to silicosis morbidity, 
OSHA notes that the estimates by Rosenman et al. (2003, Document ID 
0420) of the number of cases of silicosis estimated to occur in the 
U.S. (between 2,700 and 5,475 estimated to be in OSHA's jurisdiction 
(i.e., excluding miners)) each year is in reasonable agreement with the 
estimates derived from epidemiologic studies, assuming either a 13-year 
or 45-year working life (see Chapter VII, Table VII-2 of the FEA).
1. Surveillance Data on Silicosis Mortality
    The principal source of data on annual silicosis mortality in the 
U.S. is the National Institute for Occupational Safety and Health 
(NIOSH) Work-Related Lung Disease (WoRLD) Surveillance System (e.g., 
NIOSH, 2008c, Document ID 1308), which compiles cause-of-death data 
from death certificates reported to state vital statistics offices and 
collected by the National Center for Health Statistics (NCHS). Paper 
copies were published in 2003 and 2008 (Document ID 1307; 1308) and 
data are updated periodically in the electronic version on the CDC Web 
site (http://www.cdc.gov/eworld). NIOSH also developed and manages the 
National Occupational Respiratory Mortality System (NORMS), a data-
storage and interactive data retrieval system that reflects death 
certificate data compiled by NCHS (http://webappa.cdc.gov/ords/norms.html).
    From 1968 to 2002, silicosis was recorded as an underlying or 
contributing cause of death on 16,305 death certificates; of these, a 
total of 15,944 (98 percent) deaths occurred in males (CDC, 2005, 
Document ID 0319). Over time, silicosis-related mortality has declined 
in the U.S., but has not been eliminated. Based on the death 
certificate data, the number of recognized and coded deaths for which 
silicosis was an underlying or contributing cause decreased from 1,157 
in 1968 to 161 in 2005, corresponding to an 86-percent decline 
(Document ID 1711, p. 33; 1308, p. 55) (http://wwwn.cdc.gov/eworld). 
The crude mortality rate, expressed as the number of silicosis deaths 
per 1,000,000 general population (age 15 and higher) fell from about 
8.9 per million to about 0.5 per million over that same time frame, a 
decline of 94 percent (Document ID 1711, p. 33; 1308, p. 55) (http://wwwn.cdc.gov/eworld).
    OSHA's Review of Health Effects Literature and Preliminary QRA 
included death certificate statistics for silicosis up to and including 
2005 (Document ID 1711, p. 33). OSHA has since reviewed the more recent 
NORMS and NCHS data, up to and including 2013, which appear to show a 
general downward trend in mortality, as presented in Table V-1.

[[Page 16324]]

[GRAPHIC] [TIFF OMITTED] TR25MR16.003

    However, more detailed examination of the most recent data 
collected through NCHS (Table V-2) indicates that the decline in the 
number of deaths with silicosis as an underlying or contributing cause 
has leveled off in more recent years, suggesting that the number of 
silicosis deaths being recorded and captured by death certificates may 
be stabilizing after 30 or more years of decline.
[GRAPHIC] [TIFF OMITTED] TR25MR16.004

    Robert Cohen, M.D., representing the American Thoracic Society, 
noted this apparent plateau effect, testifying that ``[t]he data from 
the NIOSH work-related lung disease surveillance report and others show 
a plateau in silicosis

[[Page 16325]]

mortality since the 1990s, and we are concerned that that has been the 
same without any further reduction for more than 20 years. So we think 
that we still have work to do'' (Document ID 3577, p. 775).
    Some commenters raised the question about whether decedents who 
died more recently were exposed to high levels of silica (pre-1970s) 
and therefore wouldn't necessarily reflect mortalities relevant to the 
current OSHA standard (Document ID 4194, p. 9; 4209, pp. 7-8). OSHA has 
no information on the age of these decedents, or the timing of their 
exposure to silica. If we assume that workers born in 1940-1950 would 
have started working around 1960, at the earliest, and into the 1970's, 
and life expectancy in general of 70 years, or 60-70 years to account 
for years of life lost due to silicosis, most of these workers' working 
life would have been spent after the 1971 PEL went into effect. It is 
likely that some of the more recent decedents were exposed to silica 
prior to 1971; however, it is less likely that all were exposed prior 
to 1971. At the end of the day, there is no actual exposure information 
on these decedents, and this generalization does not account for 
overexposures, which have persisted over time.
2. Surveillance Data on Silicosis Morbidity
    There is no nation-wide system for collecting silicosis morbidity 
case data. The data available are from three sources: (1) The National 
Hospital Discharge Survey (Document ID 1711, p. 40-43); (2) the Agency 
for Healthcare Research and Quality's (AHRQ) Nationwide Inpatient 
Survey (Document ID 3425, p. 2; https://www.hcup-us.ahrq.gov/nisoverview.jsp); and (3) states that administer silicosis and/or 
pneumoconiosis disease surveillance (see Document ID 1711, p. 40-43; 
http://www.cdc.gov/niosh/topics/surveillance/ords/StateBasedSurveillance/stateprograms.html).
    Both of the first two sources of data on silicosis morbidity cases 
are surveys that provide estimates of hospital discharges. The first is 
the National Hospital Discharge Survey (NHDS), which was conducted 
annually from 1965-2010. The NHDS was a national probability survey 
designed to meet the need for information on characteristics of 
inpatients discharged from non-Federal short-stay hospitals in the 
United States (see http://www.cdc.gov/nchs/nhds.htm). Estimates of 
silicosis listed as a diagnosis on hospital discharge records are 
available from the NHDS for the years 1985 to 2010 (see http://www.cdc.gov/nchs/nhds.htm). National estimates were rounded to the 
nearest 1,000, and the NHDS has consistently reported approximately 
1,000 discharges/hospitalizations annually since 1980 (e.g., Document 
ID 1307; 1308). The second survey, the National (Nationwide) Inpatient 
Sample (NIS), is conducted annually by the AHRQ. Dr. Kenneth Rosenman, 
Division Chief and Professor of Medicine at Michigan State University 
and who oversees one of the few occupational disease surveillance 
systems in the U.S., testified that data from the NIS indicated that 
the nationwide number of hospitalizations where silicosis was one of 
the discharge diagnoses has remained constant, with 2,028 
hospitalizations reported in 1993 and 2,082 in 2011 (Document ID 3425, 
p. 2).
    Morbidity data are also available from the states that administer 
silicosis and/or pneumoconiosis disease surveillance. These programs 
rely primarily on hospital discharge records and also may get some 
reports of cases from the medical community and workers' compensation 
programs. Currently, NIOSH funds the State-Based Occupational Safety 
and Health Surveillance cooperative agreements (Document ID 1711, p. 
40-41; http://www.cdc.gov/niosh/topics/surveillance/ords/StateBasedSurveillance.html). All states funded under a cooperative 
agreement conduct population-based surveillance for pneumoconiosis 
(hospitalizations and mortality), and a few states (currently Michigan 
and New Jersey) have expanded surveillance specifically for silicosis 
(Document ID 1711, p. 40-42; http://www.cdc.gov/niosh/topics/surveillance/ords/StateBasedSurveillance/stateprograms.html).
    State-based hospital discharge data are a useful population-based 
surveillance data source for quantifying pneumoconiosis (including 
silicosis), even though only a small number of individuals with 
pneumoconiosis are hospitalized for that condition (Document ID 0996), 
and the data refer to hospitalizations with a diagnosis of silicosis, 
and not specific people. In addition to mortality data, NIOSH has 
updated its WoRLD Surveillance System with some state-based morbidity 
case data (http://wwwn.cdc.gov/eworld/Grouping/Silicosis/94). State-
based surveillance systems can provide more detailed information on a 
few cases of silicosis.
    NIOSH has published aggregated state case data in its WoRLD Reports 
(Document ID 1308; 1307) for two ten-year periods that overlap, 1989 to 
1998 and 1993 to 2002. State morbidity case data are compiled and 
evaluated by variables such as ascertainment source, primary industry, 
and occupations. For the time period 1989 to 1998, Michigan reported 
589 cases of silicosis, New Jersey 191 cases, and Ohio 400 cases 
(Document ID 1307, p. 69). In its last published report, for the later 
and partially overlapping time period 1993 to 2002, Michigan reported 
465 cases, New Jersey 135, and Ohio 279 (Document ID 1308, p. 72). Data 
for the years 2003 to 2011, from the CDC/NIOSH electronic report, 
eWoRld, show a modest decline in the number of cases of silicosis in 
these three states; however, decreases are not nearly as substantial as 
are those seen in the mortality rates (see Table V-3). Annual averages 
for the two ten-year periods and the nine-year time period were 
calculated by OSHA solely for the purpose of comparing cases of 
silicosis reported over time.
[GRAPHIC] [TIFF OMITTED] TR25MR16.005


[[Page 16326]]


3. Critical Comments Received on Surveillance Data
    Industry representatives, including ACC's Crystalline Silica Panel 
and Dr. Jonathan Borak, representing the Chamber of Commerce (Chamber), 
contended that the steep decline seen in the number and rate of 
silicosis deaths since 1968 proves that OSHA cannot meet its burden of 
demonstrating that a more protective standard is necessary (e.g., 
Document ID 4209, p. 10; 2376, p. 8; 4016, p. 9). Similarly, other 
commenters, such as the American Petroleum Institute, the Independent 
Petroleum Association of America, the National Mining Association, the 
American Foundry Society (AFS), the National Utility & Excavating 
Contractors Association, Acme Brick, the National Ready Mixed Concrete 
Association, and the Small Business Administration's Office of Advocacy 
stated that surveillance data demonstrate that the previous OSHA PEL 
was sufficiently effective in reducing the number of deaths from 
silicosis (Document ID 3589, Tr. 4041; 4122; 2301, pp. 3, 7-9; 2211, p. 
2; 2379, pp. 23-25; 2171, p. 1; 3730, p. 5; 3586, Tr. 3358-3360; 3589, 
Tr. 4311; 2349, pp. 3-4). Industry commenters also argued that the 
number of recorded silicosis-related deaths in recent years, as 
reflected in the surveillance data, is far lower than the number of 
lives that OSHA projected would be saved by a more stringent rule, 
indicating that OSHA's risk assessment is flawed (e.g., Document ID 
3578, Tr. 1074-1075; 4209, p. 3-4).
    The Chamber, along with others, declared that OSHA ignored steep 
declines in silicosis mortality, which in its view indicates that there 
is no further need to reduce the PEL (Document ID 4194, pp. 7-8). OSHA 
has not ignored the fact that the available surveillance data indicate 
a decline in silicosis mortality. As discussed above and in the 
proposal, the Agency has acknowledged that the available surveillance 
data do show a decline in the silicosis mortality since 1968. 
Furthermore, OSHA has no information on whether underreporting has 
increased or decreased over time, and does not believe that differing 
rates of reporting and underreporting of silicosis on death 
certificates explains the observed decline in silicosis mortality. OSHA 
believes that the reductions in deaths attributable to silicosis are 
real, and not a statistical artifact. However, OSHA disagrees with 
commenters' argument that this trend shows the lack of a need for this 
new rule. First, as explained above, there is strong evidence that the 
death certificate data do not capture the entirety of silicosis 
mortality that actually exists, due to underreporting of silicosis as a 
cause of death. Second, the stakeholders' argument assumes that 
mortality will continue to decline, even in the absence of a stronger 
silica standard, and that OSHA and workers should wait for this decline 
to hit bottom (e.g., Document ID 4209, p. 7). However, testimony in the 
record suggests that the decline in the number of deaths has leveled 
off since 2000, probably because of the deaths of those historically 
exposed to higher levels of silica occurred before then (e.g., Document 
ID 3577, p. 775).
    Third, the decline in silicosis deaths recorded over the past 
several decades cannot be solely explained by improved working 
conditions, but also reflects the decline in employment in industries 
that historically were associated with high workplace exposures to 
crystalline silica. One of OSHA's peer reviewers for the Review of 
Health Effects Literature and Preliminary QRA, Bruce Allen, commented 
that the observed decline in mortality ``. . . in no way adjusts for 
the declining employment in jobs with silica exposure,'' making ``its 
interpretation problematic. To emphasize the contribution of historic 
declines in exposure as the underlying cause is spurious; no 
information is given to allow one to account for declining employment'' 
(Document ID 3574, p. 7). The CDC/NIOSH also identified declining 
employment in heavy industries where silica exposure was prevalent as a 
``major factor'' in the reduction over time in silicosis mortality 
(Document ID 0319, p. 2). As discussed below, however, some silica-
generating operations or industries are new or becoming more prevalent.
    In his written testimony, Dr. Rosenman pointed out that there are 
``two aspects to the frequency of occurrence of disease (1) . . . the 
risk of disease based on the level of exposure and (2) the number of 
individuals at risk'' (Document ID 3425, pp. 3-4). Dr. Rosenman 
estimated the decline in the number of workers in Michigan foundries 
(75 percent) and the number of abrasive blasting companies in Michigan 
(71 percent), and then compared these percentages to the percentage 
decline in the number of recorded silicosis deaths (80 percent) over a 
similar time period. The similarities in these values led him to 
attribute ``almost all'' of the decrease in silicosis deaths to a 
decrease in the population at risk (Document ID 3425, pp. 3-4).
    Finally, OSHA's reliance on epidemiological data for its risk 
assessment purposes does not suggest that the Agency ignored the 
available surveillance data. As discussed above, the data are 
inadequate and inappropriate for estimating risks or benefits 
associated with various exposure levels, as is required of OSHA's 
regulatory process. Even in the limited cases where surveillance data 
are available, OSHA generally relies on epidemiological data, to the 
extent they include sufficiently detailed information on exposures, 
exposure sources (e.g., type of job), and health effects, to satisfy 
its statutory requirement to use the best available evidence to 
evaluate the significance of risk associated with exposure to hazardous 
substances.
    Some stakeholders provided comments to the rulemaking record 
consistent with OSHA's assessment. For example, Dr. Borak stated that 
the surveillance data ``provide little or no basis'' (Document ID 2376, 
p. 8) for OSHA to evaluate the protectiveness of the previous PELs. 
Similarly, NIOSH asserted that relying on the surveillance data to show 
that there is no need for a lower PEL or that there is no significant 
risk at 100 [mu]g/m\3\ would be ``a misuse of surveillance data'' 
(Document ID 3579, Tr. 167). NIOSH also added that, because the 
surveillance data do not include information about exposures, it is not 
the kind of data that could be used for a quantitative risk assessment. 
NIOSH concluded that surveillance data are, in fact, ``really not 
germane to the risk assessment'' (Document ID 3579, Tr. 248). OSHA 
agrees with both Dr. Borak and NIOSH that the surveillance data cannot 
and do not inform the Agency on the need for a lower PEL, nor is there 
a role for surveillance data in making its significant risk findings. 
Therefore, for its findings of significant risk at the current PEL, the 
Agency relied on evidence derived from detailed exposure-response 
relationships from well-conducted epidemiologic studies, and not 
surveillance data, which have no associated exposure information. In 
this case, epidemiologic data provided the best available evidence.
    In its testimony, the AFL-CIO pointed out that a recent U.S. 
Government Accountability Office (GAO) report on the Mine Safety and 
Health Administration's (MSHA) proposed coal dust standard references 
the National Academy of Sciences (NAS) conclusion that risk assessments 
based on epidemiological data, not surveillance data, were an 
appropriate means to assess risk for coal-dust exposures (Document ID 
4204, p. 21; 4072, Attachment 48, pp. 7-8). The NAS

[[Page 16327]]

emphasized that the surveillance data available to MSHA did not include 
individual miners' levels of exposure to coal mine dust and, therefore, 
could not be used for the purpose of estimating disease risk for 
miners. ``Based on principles of epidemiology and statistical modeling, 
measures of past exposures to coal mine dust are critical to assessing 
the relationship between miners' cumulative coal mine dust exposure and 
their risk of developing [pneumoconiosis]'' (Document ID 4072, 
Attachment 48, p. 8). The same rationale applies here. Thus, OSHA's 
decision to rely on epidemiological data is well supported by the 
record.
    Commenters from companies and industry groups also argued that they 
had no knowledge of workers acquiring silicosis in their companies or 
industry (e.g., Document ID 2384, p. 2; 2338, p. 3; 2365, p. 2; 2185, 
p. 3; 2426, p. 1). OSHA received similar comments as part of a letter 
campaign in which over 100 letters from brick industry representatives 
claimed there to be little or no silicosis observed in the industry 
despite historical exposures above the PEL (e.g., Document ID 2009). 
OSHA considered these comments and believes that many companies, 
including companies in the brick industry, may not have active medical 
surveillance programs for silicosis. Silicosis may not develop until 
after retirement as a result of its long latency period. In addition, 
silica exposures in some workplaces may be well below the final PEL as 
a result of the environment in which workers operate, including 
existing controls. Thus, OSHA believes that it is difficult to draw 
conclusions about the rate of silicosis morbidity in specific 
workplaces without having detailed information on medical surveillance, 
silica exposures, and follow-up. This is why OSHA relies heavily on 
epidemiological studies with detailed exposure data and extended 
follow-up, and uses these data to evaluate exposure-response 
relationships to assess health risks at the preceding and new PELs.
    Commenters also argued that, due to the long latency of the 
disease, silicosis cases diagnosed today are the result of exposures 
that occurred before the former PELs were adopted, and thus reflect 
exposures considerably higher than the previous PELs (e.g., Document ID 
2376, p. 3; 2307, p. 12; 4194, p. 9; 3582, Tr. 1935). OSHA notes that 
the evidence shows that the declining trend in silicosis mortality does 
not provide a complete picture with regard to silicosis trends in the 
United States. Although many silicosis deaths reported today are likely 
the result of higher exposures (both magnitude and duration), some of 
which may have occurred before OSHA adopted the previous PELs, 
silicosis cases continue to occur today--some in occupations and 
industries where exposures are new and/or increasing. For example, five 
states reported cases of silicosis in dental technicians for the years 
1994 to 2000 (CDC, MMWR Weekly, 2004, 53(09), pp. 195-197), for the 
first time. For the patients described in this report, the only 
identified source of crystalline silica exposure was their work as 
dental technicians. Exposure to respirable crystalline silica in dental 
laboratories can occur during procedures that generate airborne dust 
(e.g., mixing powders, removing castings from molds, grinding and 
polishing castings and porcelain, and using silica sand for abrasive 
blasting). In 2015, the CDC reported the first case of silicosis 
(progressive massive fibrosis) associated with exposure to quartz 
surfacing materials (countertop fabrication and installation) in the 
U.S. The patient was exposed to dust for 10 years from working with 
conglomerate or quartz surfacing materials containing 70%-90% 
crystalline silica. Cases had previously been reported in Israel, Italy 
and Spain (MMWR, 2015, 64(05); 129-130). Recently, hazardous silica 
exposures have been newly documented during hydraulic fracturing of gas 
and oil wells (Bang et al., MMWR, 2015, 64(05); 117-120).
    Dr. Rosenman's testimony provides support for this point. He 
testified that newer industries with high silica exposures may also be 
under-recognized because workers in those industries have not yet begun 
to be diagnosed with silicosis due to the latency period (Document ID 
3577, p. 858). Dr. Rosenman submitted to the record a study by Valiante 
et al. (2004, Document ID 3926) that identified newly exposed 
construction workers in the growing industry of roadway repair, which 
began using current methods for repair in the 1980s. These methods use 
quick-setting concrete that generates dust containing silica above the 
OSHA PEL when workers perform jackhammering, and sawing and milling 
concrete operations. State surveillance systems identified 576 
confirmed silicosis cases in New Jersey, Michigan, and Ohio that were 
reported to NIOSH for the years 1993 through 1997. Of these, 45 (8 
percent) cases were in construction workers, three of which had been 
engaged in highway repair.
    Sample results for this study indicated a significant risk of 
overexposure to crystalline silica for workers who performed the five 
highway repair tasks involving concrete. Sample results in excess of 
the OSHA PEL were found for operating a jackhammer (88 percent of 
samples), sawing concrete and milling concrete tasks (100 percent of 
samples); cleaning up concrete tasks (67 percent of samples); and 
drilling dowels (100 percent of samples). No measured exposures in 
excess of the PEL were found for milling asphalt and cleaning up 
asphalt; however, of the eight samples collected for milling asphalt, 
six (55 percent) results approached the OSHA PEL, and one was at 92 
percent of the PEL. No dust-control measures were in place during the 
sampling of these highway repair operations.
    The authors pointed out that surveillance systems such as those 
implemented by these states are limited in their ability to detect 
diseases with long latencies in highway repair working populations 
because of the relatively short period of time that modern repair 
methods had been in use when the study was conducted. Nevertheless, a 
few cases were identified, although the authors explain that the work 
histories of these cases were incomplete, and the authors recommended 
ongoing research to evaluate the silicosis disease potential among this 
growing worker population (Document ID 3926, pp. 876-880). In 
construction, use of equipment such as blades used on handheld saws to 
dry-cut masonry materials have increased both efficiency and silica 
exposures for workers over the past few decades (Document ID 4223, p. 
11-13). Exposure data collected by OSHA as part of its technological 
feasibility analysis demonstrates that exposures frequently exceed 
previous exposure limits for these operations when no dust controls are 
used (see Chapter IV of the FEA). Another operation seeing new and 
increasing exposures to respirable crystalline silica is hydraulic 
fracturing in the oil and gas industry (Document ID 3588, p. 3773). 
Information in the record from medical professionals noted that lung 
diseases caused by silica exposures are ``not relics of the past,'' and 
that they continue to see cases of silicosis and other related 
diseases, even among younger workers who entered the workforce after 
the former PEL was enacted (see Document ID 3577, Tr. 773).
    Furthermore, the general declining trend seen in the death 
certificate data is considerably more modest in silicosis morbidity 
data. In his written testimony, Dr. Rosenman stated that the nationwide 
number of hospitalizations where silicosis was one of the discharge 
diagnoses has remained constant, with 2,028 hospitalizations reported 
in 1993

[[Page 16328]]

and 2,082 in 2011 (Document ID 3425, p. 2). It is the opinion of 
medical professionals including the American Thoracic Society and the 
American College of Chest Physicians that these hospitalizations likely 
represent ``the tip of the iceberg'' (of silicosis cases) since milder 
cases are not likely to be admitted to the hospital (Document ID 2175, 
p. 3). Again, this evidence shows that the declining trend observed in 
silicosis mortality statistics does not provide a complete picture with 
regard to silicosis trends in the United States. While silicosis 
mortality has decreased substantially since records were first 
available in 1968, the number of silicosis related deaths appears to 
have leveled off (see Table V-2; Document ID 3577, Tr. 775). Workers 
are still dying from silicosis today, and new cases are being 
identified by surveillance systems, where they exist.
    Based on the testimony and evidence described above, OSHA finds 
that the surveillance data describing trends in silicosis mortality and 
morbidity provide useful evidence of a continuing problem, but are not 
suitable for evaluating either the adequacy of the previous PELs or 
whether a more protective standard is needed. In fact, it would not be 
possible to derive estimates of risk at various exposure levels from 
the available surveillance data for silica. OSHA therefore 
appropriately continues to rely on epidemiological data and its 
quantitative risk assessment to support the need to reduce the previous 
PELs in its final rule.
    Commenters also argued that OSHA has failed to prove that a new 
standard is necessary because silica-associated deaths are due to 
existing exposures in excess of the previous PELs; therefore, the 
Agency should focus on better enforcing the previous PELs, rather than 
enacting a new standard (e.g., Document ID 2376, p. 8; 2307, p. 12; 
4016, pp. 9-10; 3582, Tr. 1936). OSHA does not find this argument 
persuasive. First, many of the commenters used OSHA's targeted 
enforcement data to make this point. These data were obtained during 
inspections where OSHA suspected that exposures would be above the 
previous PELs. Consequently, the data by their very nature are skewed 
in the direction of exceeding the previous PELs, and such enforcement 
serves a deterrence function, encouraging future compliance with the 
PEL.
    Second, not all commenters agreed that overexposures were 
``widespread.'' A few other commenters (e.g., AFS) thought that OSHA 
substantially overstated the number of workers occupationally exposed 
above 100 [mu]g/m\3\ in its PEA (Document ID 2379, p. 25). However 
OSHA's risk analyses evaluated various exposure levels in determining 
risks to workers, and did not rely on surveillance data, which rarely 
have associated exposure data. Although OSHA relied on exposure data 
from inspections to assess technological feasibility, it did not rely 
on inspection data for its risk assessment because these exposure data 
are not tied to specific health outcomes. Instead, the exposure data 
used for risk assessment purposes is found in the scientific studies 
discussed throughout this preamble section.
    The surveillance data are also not comparable to OSHA's estimate of 
deaths avoided by the final rule because, as is broadly acknowledged, 
silicosis is underreported as a cause of death on death certificates. 
Thus, the surveillance data capture only a portion of the actual 
silicosis mortality. This point was raised by several rulemaking 
participants, including Dr. Rosenman; Dr. James Cone, MD, MPH, 
Occupational Medicine Physician at the New York City Department of 
Health, the AFL-CIO; and the American Thoracic Society (ATS) (Document 
ID 3425, p. 2; 3577, Tr. 855, 867; 4204, p. 17; 2175, p. 3; 3577, Tr. 
772).
    The rulemaking record includes one study that evaluated 
underreporting of silicosis mortality. Goodwin et al. (2003, Document 
ID 1030) estimated, through radiological confirmation, the prevalence 
of unrecognized silicosis in a group of decedents presumed to be 
occupationally exposed to silica, but whose causes of death were 
identified as respiratory diseases other than silicosis. In order to 
assess whether silicosis had been overlooked and under-diagnosed by 
physicians, the authors looked at x-rays of decedents whose underlying 
cause of death was listed as tuberculosis, cor pulmonale, chronic 
bronchitis, emphysema, or chronic airway obstruction, and whose usual 
industry was listed as mining, construction, plastics, soaps, glass, 
cement, concrete, structural clay, pottery, miscellaneous mineral/
stone, blast furnaces, foundries, primary metals, or shipbuilding and 
repair.
    Any decedent found to have evidence of silicosis on chest x-ray 
with a profusion score of 1/0 was considered to be a missed diagnosis. 
Of the 177 individuals who met study criteria, radiographic evidence of 
silicosis was found in 15 (8.5 percent). The authors concluded that 
silicosis goes undetected even when the state administers a case-based 
surveillance system. Goodwin et al. (2003, Document ID 1030) also cites 
mortality studies of Davis et al. (1983, Document ID 0999) and Hughes 
(1982, Document ID 0362) who reported finding decedents with past chest 
x-ray records showing evidence of silicosis but no mention of silicosis 
on the death certificate.
    The Goodwin et al. (2003) study illustrates the importance of 
information about the decedent's usual occupation and usual industry on 
death certificates. Yet for the years 1985 to 1999, only 26 states 
coded this information for inclusion on death certificates. If no 
occupational information is available, recognizing exposure to silica, 
which is necessary to diagnose silicosis, becomes even more difficult, 
further contributing to possible underreporting.
    Dr. Rosenman, a physician, epidemiologist and B-reader, testified 
that in his research he found silicosis recorded on only 14 percent of 
the death certificates of individuals with confirmed silicosis 
(Document ID 3425, p. 2; 3577, Tr. 854; see also 3756, Attachment 11). 
This means that as much as 86 percent of deaths related to silicosis 
are missing from the NIOSH WoRLD database, substantially compromising 
the accuracy of the surveillance information. Dr. Rosenman also found 
that silicosis is listed as the cause of death in a small percentage of 
individuals who have an advanced stage of silicosis; 18 percent in 
those with progressive massive fibrosis (PMF) and 10 percent in those 
with category 3 profusion.
    As noted above, factors that contribute to underreporting by health 
care providers include lack of information about exposure histories and 
difficulty recognizing occupational illnesses that have long latency 
periods, like silicosis (e.g., Document ID 4214, p. 13; 3584, Tr. 
2557). Dr. Rosenman's testimony indicated that many physicians are 
unfamiliar with silicosis and this lack of recognition is one factor 
that contributes to the low recording rate for silicosis on death 
certificates (Document ID 3577, Tr. 855). In order to identify cases of 
silicosis, a health care provider must be informed of the patient's 
history of occupational exposure to dust containing respirable silica, 
a critical piece of information in identifying and reporting cases of 
silicosis. However, information on a decedent's usual occupation and/or 
industry is often not available at the time of death or is too general 
to be useful. If the physician completing the death certificate is 
unaware of the decedent's occupational exposure history to crystalline 
silica, and does not have that information available to her/him on a 
medical record, a diagnosis of silicosis on the death certificate is

[[Page 16329]]

unlikely. According to a study submitted by the Laborers' Health and 
Safety Fund of North America, (Wexelman et al., 2010), a sample of 
physician residents surveyed in New York City did not believe that 
cause of death reporting is accurate; this was a general finding, and 
not specific to silicosis (Document ID 3756, Attachment 7).
    The ATS and the American College of Chest Physicians commented that 
physicians often fail to recognize or misdiagnose silicosis as another 
lung disease on the death certificate, leading to under-reporting on 
death certificates (3577, Tr. 821, 826-827) and under-recognize and 
underreport cases of silicosis (Document ID 2175, p. 3). As Dr. 
Weissman from NIOSH responded:

    . . . it's well known that death certificates don't capture all 
of the people that have a condition when they pass away, and so 
there would be many that probably would not be captured if the 
silicosis didn't directly contribute to the death and depending on 
who filled out the death certificate, and the conditions of the 
death and all those kinds of things. So it's an under-representation 
of people who die with the condition . . . . (Document ID 3579, pp. 
166-167).

    Although there is little empirical evidence describing the extent 
to which silicosis is underreported as a cause of death, OSHA finds, 
based on this evidence as well as on testimony in the record, that the 
available silicosis surveillance data are likely to significantly 
understate the number of deaths that occur in the U.S. where silicosis 
is an underlying or contributing cause. This is in large part due to 
physicians and medical residents who record causes of death not being 
familiar or having access to the patient's work or medical history (see 
Wexelman et al., 2010, Document ID 3756, Attachment 7; Al-Samarri et 
al., Prev. Chronic Dis. 10:120210,2013). According to Goodwin et al. 
(2003, Document ID 1030, p. 310), most primary care physicians do not 
take occupational histories, nor do they receive formal training in 
occupational disease. They further stated that, since it is likely that 
a person would not retain the same health care provider over many 
years, even if the presence of silicosis in a patient might have been 
known by a physician who cared for them, it would not necessarily be 
known by another physician or resident who recorded cause of death 
years or decades later and who did not have access to the patient's 
medical or work history. OSHA finds the testimony of Dr. Rosenman 
compelling, who found that silicosis was not recorded as an underlying 
or contributing cause of death even where there was chest x-ray 
evidence of progressive massive fibrosis related to exposure to 
crystalline silica.
    Some commenters stated that the decline in silicosis mortality 
demonstrates that there is a threshold for silicosis above the prior 
PEL of 100 [mu]g/m\3\ (Document ID 4224, p. 2-5; 3582, Tr. 1951-1963). 
OSHA finds this argument irrelevant as the threshold concept does not 
apply to historical surveillance data. As noted above and discussed in 
Section V.I, Comments and Responses Concerning Threshold for Silica-
Related Diseases, OSHA believes that surveillance data should not be 
used for quantitative risk analysis (including determination of 
threshold effects) because it lacks an exposure characterization based 
on sampling. Thus, the surveillance data cannot demonstrate the 
existence of a population threshold.
    There is also evidence in the record that silicosis morbidity 
statistics reviewed earlier in this section are underreported. This can 
be due, in part, to the relative insensitivity of chest roentgenograms 
for detecting lung fibrosis. Hnizdo et al. (1993) evaluated the 
sensitivity, specificity and predictive value of radiography by 
correlating radiological and pathological (autopsy) findings of 
silicosis. ``Sensitivity'' and ``specificity'' refer to the ability of 
a test to correctly identify those with the disease (true positive 
rate), and those without the disease (true negative). Because 
pathological findings are the most definitive for silicosis, findings 
on biopsy and autopsy provide the best comparison for determining 
sensitivity and specificity of chest imaging.
    The study used three readers and defined a profusion score of 1/1 
as positive for silicosis. Sensitivity was defined as the probability 
of a positive radiological reading (ILO category >1/1) given that 
silicotic nodules were found in the lungs at autopsy. Specificity was 
defined as the probability of a negative radiological reading (ILO 
category <1/1) given that no, or only an insignificant number of 
silicotic nodules were found at autopsy. The average sensitivity values 
were low for each of the three readers (0.39, 0.37, and 0.24), whereas 
the average specificity values were high (0.99, 0.97, and 0.98). For 
all readers, the proportion of true positive readings (i.e., the 
sensitivity) increased with the extent of silicosis found at autopsy 
(Document ID 1050).
    In the only published study that quantified the extent of 
underreporting of silicosis mortality and morbidity, Rosenman et al. 
estimated the number of new cases of silicosis occurring annually in 
the U.S. at between 3,600 and 7,300 based on the ratio of living to 
deceased persons identified and confirmed as silicotics in the Michigan 
surveillance data and extrapolating that ratio using the number of 
deaths due to silicosis for the U.S. as a whole (2003, Document ID 
0420). OSHA reviewed the study in its Review of the Health Effects 
Literature (Document ID 1711, p. 48). Patrick Hessel, Ph.D., criticized 
the methods used by Dr. Rosenman, and deemed the resulting estimates 
unreliable, stating that the actual number of new silicosis cases 
arising each year is likely to be lower than the authors estimated 
(Document ID 2332, p. 2; 3576, Tr. 323-331).
    OSHA disagrees with the criticisms that Dr. Hessel, commenting on 
behalf of the Chamber, offered on the study by Rosenman et al. (2003, 
Document ID 0420). Specifically, Dr. Hessel argued: (1) That the 
silicosis-related deaths used by Rosenman et al. occurred during the 
period 1987 through 1996, and do not reflect the declining numbers 
after that time period; (2) that the Michigan surveillance system 
relied on a single B-reader who was biased toward finding silicosis in 
patients who were brought to his attention for suspected silicosis; and 
(3) that the Michigan population was not representative of the rest of 
the country, since about 80 percent of the workers diagnosed with 
silicosis worked in foundries, which are not prevalent in most other 
states. Finally, in his hearing testimony, Dr. Hessel criticized the 
capture-recapture analysis used by Rosenman et al. to estimate the 
extent of underreporting of cases, stating that a number of underlying 
assumptions used in the analysis were not met (Document ID 3576, Tr. 
323-332).
    Dr. Rosenman addressed many of these criticisms in the study and at 
the rulemaking hearing. Regarding the fact that the number of 
silicosis-related deaths does not reflect the decline in deaths after 
1996, Dr. Rosenman testified that, although the number of recorded 
silicosis deaths have declined since then, the ratio of cases to deaths 
has increased because the number of cases has not declined. ``The 
living to dead ratio that we reported in our published study in 2003 
was 6.44. This ratio has actually increased in recent years to 15.2. A 
similar ratio . . . [was] found in the New Jersey surveillance data, 
which went from 5.97 to 11.5 times'' (Document ID 3577, Tr. 854). If 
one were to apply the more recent ratio from Michigan (more than double 
the ratio used by Rosenman et al.) to the more recent number of deaths 
in the country (about half that recorded in the mid-1990s; see Table V-
1) to extrapolate

[[Page 16330]]

the number of silicosis cases for the U.S. overall, the result would be 
even greater than the estimate in Rosenman et al. (2003).
    At the hearing, Dr. Rosenman testified that he was the sole B-
reader of lung x-rays for the study, and that he received the x-ray 
films from other radiologists who suspected but did not confirm the 
presence of silicosis (Document ID 3577, Tr. 877-878). Dr. Rosenman, 
while acknowledging that there could be differences between readers in 
scoring x-ray films, argued that such differences in scoring--for 
example, whether a film is scored a 3/3, 3/2, or 2/3--did not affect 
this study since the study design only required that a case be 
identified and confirmed (diagnosis requires a chest radiograph 
interpretation showing rounded opacities of 1/0 or greater profusion) 
(Document ID 3577, Tr. 877-878; 0420, p. 142).
    Dr. Rosenman also addressed the criticism that Michigan's worker 
population with silica exposure is significantly different from the 
rest of the country. In the study, Rosenman et al. reported that the 
ratio of cases to deaths was about the same for Ohio as for Michigan 
and, during the public hearing, Dr. Rosenman testified that the ratio 
of cases to deaths for New Jersey was also similar to Michigan's (11.5 
vs. 15.2) (Document ID 0420, p. 146; 3577, Tr. 854). This similarity 
was despite the fact that New Jersey had a different industrial mix, 
with fewer foundries (Document ID 3577, Tr. 878). Furthermore, the 
estimates made by Rosenman et al. depended on the ratio of cases to 
deaths in Michigan, rather than just the number of cases in that state. 
The authors believed that the ratio would be unaffected by the level of 
industrialization in Michigan (Document ID 0420, p. 146).
    Finally, regarding the capture-recapture analysis, OSHA notes that 
Dr. Hessel acknowledged that this technique has been used in 
epidemiology to estimate sizes of populations identified from multiple 
overlapping sources (Document ID 2332, p. 2), which is the purpose for 
which Rosenman et al. used the approach. In addition, the Rosenman et 
al. study noted that the assumptions used in capture-recapture analysis 
could not be fully met in most epidemiological study designs, but that 
the effect of violating these assumptions was either negligible or was 
evaluated using interaction terms in the regression models employed. 
The investigators also reported that the capture-recapture analysis 
used on Ohio state surveillance data found that the total number of 
cases estimated for the state was between 3.03 and 3.18 times the 
number of cases identified, a result that is comparable to that for 
Michigan (Document ID 0420, pp. 146-147). After considering Dr. 
Hessel's written testimony, Dr. Rosenman testified that ``. . . overall 
I don't think his comments make a difference in my data'' (Document ID 
3577, Tr. 877).
    OSHA finds all of Dr. Rosenman's responses to Dr. Hessel's 
criticisms to be reasonable. And based on Dr. Rosenman's comments and 
testimony, OSHA continues to believe that the Rosenman et al. (2003) 
analysis and resulting estimates of the number of new silicosis cases 
that arise each year are reasonable. Additionally, Dr. Rosenman, in 
updating his data for his testimony for this rulemaking, found that the 
ratio had increased from 6.44 in the published study to 15.2 times in 
more recent years (Document ID 3577, Tr. 854). The study supports 
OSHA's hypothesis that silicosis is a much more widespread problem than 
the surveillance data suggest and that OSHA's estimates of the non-
fatal illnesses that will be avoided as a result of this new silica 
standard are not unreasonable. Regardless, even assuming commenters' 
criticisms have merit, they do not significantly affect OSHA's own 
estimates from the epidemiological evidence of the risks of silicosis.
    Accordingly, after careful consideration of the available 
surveillance data, stakeholders' comments and testimony, and the 
remainder of the record as a whole, OSHA has determined that the 
available silicosis surveillance data are useful for providing context 
and an illustration of a significant general trend in the reduction of 
deaths associated with silicosis over the past four to five decades. As 
discussed above, and in large part because the data themselves are 
limited and incomplete, OSHA believes reliance upon them for the 
purpose of estimating the magnitude of the risk would be inappropriate. 
The Agency has chosen instead to follow its well-established practice 
of relying on epidemiological data to meet its burden of demonstrating 
that workers exposed to respirable crystalline silica at the previous 
PELs face a significant risk of developing silicosis and that such risk 
will be reduced when the new limit is fully implemented.

F. Comments and Responses Concerning Lung Cancer Mortality

    OSHA received numerous comments regarding the carcinogenic 
potential of crystalline silica as well as the studies of lung cancer 
mortality that the Agency relied upon in the Preliminary Quantitative 
Risk Assessment (QRA). Many of these comments, particularly from the 
ACC, asserted that (1) OSHA should have relied upon additional 
epidemiological studies, and (2) the studies that the Agency did rely 
upon (Steenland et al., 2001a, as re-analyzed in ToxaChemica, 2004; 
Rice et al., 2001; Attfield and Costello, 2004; Hughes et al., 2001; 
and Miller and MacCalman, 2009) were flawed or biased. In this section, 
OSHA presents these comments and its responses to them.
1. Carcinogenicity of Crystalline Silica
    As discussed in the Review of Health Effects Literature and 
Preliminary QRA (Document ID 1711, pp. 76-77), in 1997, the World 
Health Organization's International Agency for Research on Cancer 
(IARC) conducted a thorough expert committee review of the peer-
reviewed scientific literature and classified crystalline silica dust, 
in the form of quartz or cristobalite, as Group 1, ``carcinogenic to 
humans'' (Document ID 2258, Attachment 8, p. 211). IARC's overall 
finding for silica was based on studies of nine occupational cohorts 
that it considered to be the least influenced by confounding factors 
(Document ID 1711, p. 76). In March of 2009, 27 scientists from eight 
countries participated in an additional IARC review of the scientific 
literature and subsequently, in 2012, IARC reaffirmed that respirable 
crystalline silica dust is a Group 1 human carcinogen that causes lung 
cancer (Document ID 1473, p. 396). Additionally, in 2000, the National 
Toxicology Program (NTP) of HHS concluded that respirable crystalline 
silica is a known human carcinogen (Document ID 1164, p. 1).
    The ACC, in its pre-hearing comments, questioned the carcinogenic 
potential of crystalline silica, asserting that IARC's 1996 
recommendation that crystalline silica be classified as a Group 1 
carcinogen was controversial (Document ID 2307, Attachment A, p. 29). 
The ACC cited Dr. Patrick Hessel's 2005 review of epidemiological 
studies, published after the initial IARC determination, in which he 
concluded that ``the silica-lung cancer hypothesis remained 
questionable'' (Document ID 2307, Attachment A, p. 31). The ACC 
reasserted this position in its post-hearing brief, contending that 
``epidemiological studies have been negative as often as they have been 
positive'' (Document ID 4209, pp. 33-34).
    After the publication of Dr. Hessel's 2005 review article, IARC 
reaffirmed in 2012 its earlier Group 1 classification for crystalline 
silica dust (Document ID 1473). As pointed out by Steenland and

[[Page 16331]]

Ward, IARC is one of ``2 agencies that are usually considered to be 
authoritative regarding whether a substance causes cancer in humans,'' 
the other being the NTP, which has also determined crystalline silica 
to be carcinogenic on two separate occasions (2013, article included in 
Document ID 2340, p. 5). David Goldsmith, Ph.D., who coauthored one of 
the first published articles linking silica exposure to lung cancer, 
echoed Steenland and Ward:

    It is important to recognize that evidence for silica's 
carcinogenicity has been reviewed three times by the International 
Agency for Research on Cancer, once in 1987, 1997, and 2012. It has 
been evaluated by California's Proposition 65 in 1988, by the 
National Toxicology Program in 2000 and reaffirmed in 2011, and by 
the National Institute for Occupational Safety and Health in 2002 
(Document ID 3577, Tr. 861-862).

    Multiple organizations with great expertise in this area, including 
the American Cancer Society, submitted comments supporting the thorough 
and authoritative nature of IARC's findings regarding silica's 
carcinogenicity (e.g., Document ID 1171; 1878). OSHA likewise places 
great weight on the IARC and NTP classifications and, based on their 
findings, concludes that the carcinogenic nature of crystalline silica 
dust has been well established. Further support for this finding is 
discussed in Section V.L, Comments and Responses Concerning Causation.
2. Silicosis and Lung Cancer
    In addition to debating the conclusions of IARC, Peter Morfeld, Dr. 
rer. medic, testifying on behalf of the ACC Crystalline Silica Panel, 
concluded that OSHA's risk estimates for lung cancer are ``unreliable'' 
because they ``ignore threshold effects and the apparent mediating role 
of silicosis'' (Document ID 2307, Attachment 2, p. 16). Dr. Morfeld 
argued that silicosis is a necessary prerequisite for silica-related 
lung cancer. Commenters' arguments about silicosis being a prerequisite 
for lung cancer and silicosis having a threshold are linked; if it were 
shown both that silicosis requires a certain threshold of exposure and 
that only persons with silicosis get lung cancer, then silica-related 
lung cancer would also have an exposure threshold. As discussed in 
Section V.I, Comments and Responses Concerning Thresholds for Silica-
Related Diseases, commenters claimed that there is a threshold for 
silicosis above the previous PEL for general industry, which would make 
any threshold for lung cancer above that level as well. OSHA discusses 
these comments in detail in that section, and has determined that even 
if lung cancer does not occur in the absence of silicosis, the record 
strongly supports the conclusion that workers exposed to respirable 
crystalline silica would still be at risk of developing lung cancer as 
a result of their exposure because silicosis can develop among workers 
whose average and cumulative exposures are below the levels permitted 
by the previous PELs.
    OSHA received comments from other stakeholders, including Robert 
Glenn, representing the Brick Industry Association, and the AFS on the 
possible mediating role of silicosis in the development of lung cancer 
(Document ID 2307, pp. 29-35; 2343, Attachment 1, pp. 42-45; 2379, 
Attachment 2, pp. 24-25). The ACC cited several review articles in 
support of its claim that ``silica exposures have not been shown to 
increase the risk of lung cancer in the absence of silicosis'' 
(Document ID 2307, Attachment A, pp. 29, 32, 35). These articles 
included: A 2004 review of studies by Kurihara and Wada that found that 
while silicosis is a risk factor for lung cancer, exposure to silica 
itself may not be a risk factor (Document ID 1084); a 2006 review by 
Pelucchi et al. that determined that the issue of whether silica itself 
increases lung cancer risk in the absence of silicosis has not been 
resolved (Document ID 0408); and a 2011 review by Erren et al. that 
concluded it is unclear whether silica causes lung cancer in persons 
who do not already have silicosis (Document ID 3873). Similarly, the 
AFS cited a review by the Health and Safety Executive (2003) that 
concluded that increased risks of lung cancer are restricted to those 
groups with the highest cumulative exposures, with evidence tending to 
show that excess lung cancer mortality is restricted to those with 
silicosis (Document ID 2379, Attachment 2, pp. 24-25). Having reviewed 
the studies cited by commenters, OSHA has come to the conclusion that 
none of the cited studies demonstrates that silicosis is a necessary 
precursor to lung cancer, but acknowledges that uncertainty remains 
about what percentage of lung cancers in silica-exposed workers are 
independent of silicosis.
    Similarly, the ACC stated that none of the studies of lung cancer 
mortality that OSHA relied upon in the Preliminary QRA demonstrates 
that silica exposure causes lung cancer in the absence of silicosis 
(Document ID 2307, Attachment A, p. 66). During the rulemaking hearing, 
NIOSH scientists addressed the issue of whether silicosis is a 
necessary precursor to the development of lung cancer. They stated that 
it is a difficult issue to resolve because the two diseases may have a 
similar pathway, such that they can develop independently but still 
appear correlated. Mr. Robert Park also added that:

    [S]ilicosis isn't detectable until there's splotches on the lung 
that are visible in x-rays. So prior to that point, somebody could 
have [been] developing lung disease and you just can't see it. So, 
of course, people that have silicosis are going to have higher lung 
cancer, and it's going to look like a threshold because you didn't 
see the silicosis in other people that have lower lung cancer risk. 
To really separate those two, you'd have to do a really big study. 
You'd have to have some measures, independent measures of lung 
physiological pathology, and see what's going on with silicosis as a 
necessary condition for development of lung cancer (Document ID 
3579, Tr. 245-247).

    Similarly, David Weissman, MD, concurred that ``there's quite a bit 
of reason as Bob [Park] said to think that the two processes 
[development of silicosis and development of lung cancer] don't require 
each other, and it would be extraordinarily difficult to sort things 
out in human data'' (Document ID 3579, Tr. 247). Indeed, Checkoway and 
Franzblau (2000) reviewed the epidemiological literature addressing 
this topic, and found that the ``limitations of existing epidemiologic 
literature that bears on the question at hand suggest that prospects 
for a conclusive answer are bleak'' (Document ID 0323, p. 257). The 
authors concluded that silicosis and lung cancer should be treated in 
risk assessments as ``separate entities whose cause/effect relations 
are not necessarily linked'' (Document ID 0323, p. 257). Brian Miller, 
Ph.D., a peer reviewer of OSHA's Review of Health Effects Literature 
and Preliminary QRA, likewise wrote in his post-hearing comments, ``I 
consider this issue unanswerable, given that we cannot investigate for 
early fibrotic lesions in the living, but must rely on radiographs'' 
(Document ID 3574, p. 31).
    During the public rulemaking hearing, several stakeholders pointed 
to a recent study of Chinese pottery workers and miners by Liu et al. 
(2013, article included in Document ID 2340) as evidence that exposure 
to crystalline silica is associated with lung cancer even in the 
absence of silicosis (Document ID 3580, Tr. 1232-1235; 3577, Tr. 803-
804, 862-863). In this study, the authors excluded 15 percent of the 
cohort (including 119 lung cancer deaths) with radiographic evidence of 
silicosis and found that the risk of lung cancer mortality still 
increased with cumulative exposure to crystalline silica, suggesting 
that clinically-

[[Page 16332]]

apparent silicosis is not a prerequisite for silica-related lung cancer 
(article included in Document ID 2340, pp. 3, 7).
    The ACC argued that it is ``premature to draw that conclusion,'' 
stating that the Liu study's conclusions are not supported by the data 
and raising questions about uncertainty in the exposure estimates, 
modeling and statistics, confounding, and the silicosis status of 
cohort members (Document ID 2307, Attachment A, p. 48; 4027, pp. 35-36; 
4209, pp. 40-51). With regard to exposure estimates, the ACC had a 
number of concerns, including that conversion factors determined by 
side-by-side sampling in 1988-1989 were used to convert Chinese total 
dust concentrations to respirable crystalline silica exposures 
(Document ID 4209, pp. 40-41). Dr. Cox expressed concern that these 
conversion factors from 1988-1989 might not have been applicable to 
other time periods, as particle size distributions could change over 
time (Document ID 4027, p. 32). OSHA acknowledges this concern, but 
given the ``insufficient historical particle size data . . . to analyze 
whether there were changes in particle size distributions from the 
1950s to the 1990s,'' believes that the authors were justified in 
making their exposure assumptions (Document ID 4027, p. 32). Dr. Cox's 
concerns involving modeling and statistics (see Document ID 4027, pp. 
33-36) in the study, including the absence of model diagnostics, the 
use of inappropriate or misspecified models, the lack of a discussion 
of residual confounding and model uncertainty, and the use of 
inappropriate data adjustments and transformations, are discussed in 
detail in Section V.J, Comments and Responses Concerning Biases in Key 
Studies.
    On the issue of confounding, the ACC noted that Liu et al. (2013) 
used a subcohort of 34,018 participants from 6 tungsten mines, 1 iron 
mine, and 4 potteries derived from a total cohort of 74,040 
participants from 29 mines and pottery factories studied previously by 
Chen et al. (2007, Document ID 1469; 2307, Attachment A, pp. 48-50). 
Liu et al. (2013) excluded participants in the original cohort if 
detailed information on work history or smoking was not available, or 
if they worked in copper mines or tin mines where the analysis could be 
confounded by other exposures, namely radon and carcinogenic polycyclic 
aromatic hydrocarbons (PAHs) in the former and arsenic in the latter 
(article included in Document ID 2340, p. 2). The ACC's main concern 
was that Liu et al. (2013) did not adjust for these confounders in 
their analyses, but rather claimed that there were no confounding 
exposures in their smaller cohort on the basis of the exclusion 
criteria (Document ID 2307, Attachment A, p. 49).
    The ACC also noted that Chen et al. (2007) stated that the Chinese 
pottery workers were exposed to PAHs, and some of the iron-copper 
miners were exposed to PAHs and radon progeny (Document ID 2307, 
Attachment A, p. 49). Chen et al. (2007) initially found an association 
between respirable silica and lung cancer mortality in the pottery 
workers and iron-copper miners, but it disappeared after adjusting for 
PAH exposures (Document ID 1469). In the tungsten miners, Chen et al. 
(2007) found no significant association for lung cancer mortality, 
while Liu et al. (2013) did. Similarly, the ACC pointed out that a 
subsequent study by Chen et al. (2012, article included in Document ID 
2340) also failed to find a statistically significant increase in the 
hazard ratio for lung cancer, meaning that there was no significant 
positive exposure-response relationship between cumulative silica 
exposure and lung cancer mortality (Document ID 4209, p. 45). Dr. 
Morfeld concluded, ``Unless and until these issues are resolved, Liu et 
al. (2013) should not be used to draw conclusions regarding exposure-
response relationships between RCS [respirable crystalline silica], 
silicosis and lung cancer risk'' (Document ID 2307, Attachment 2, pp. 
15-16).
    During the public hearing, counsel to the ACC asked Dr. Steenland, 
a co-author on the Liu et al. (2013) study, if he would provide 
measurement data on the PAH exposures in the potteries, as well as 
present the data from the Liu et al. (2013) study separately for 
pottery factories and tungsten mines, as they were in Chen et al. 
(2007, Document ID 1469) (Document ID 3580, Tr. 1237-1240). Dr. 
Steenland subsequently provided the requested data for inclusion in the 
rulemaking record (Document ID 3954).
    With respect to the PAH data for the potteries, Dr. Weihong Chen, 
the study's first author, reported that, in measurements in 1987-1988 
in the four potteries that were excluded from the Liu et al. (2013) 
analysis, the mean total PAHs was 38.9 [micro]g/m\3\ and the mean 
carcinogenic PAHs was 4.7 [micro]g/m\3\. In the four potteries that 
were included in the Liu et al. (2013) analysis, the mean total and 
carcinogenic PAHs, as measured in 1987-1988, were substantially lower 
at 11.6 and 2.5 [micro]g/m\3\, respectively. When the measurements were 
repeated in 2006, the mean total and carcinogenic PAHs in the four 
potteries included in the analysis were still lower, at 2.2 and 0.08 
[micro]g/m\3\, levels that were ``not much higher than environmental 
PAH in many [Chinese] cities'' (Document ID 3954, p. 2). Dr. Chen also 
reported that, when comparing levels within six job titles, there was 
no significant correlation between total or carcinogenic PAHs (based on 
the 2006 measurements) and respirable silica dust. When the results 
were presented separately for the mines and potteries, in analyses 
using continuous cumulative exposure, the relationship between silica 
exposure and lung cancer mortality remained significant for the pottery 
factories, but not the metal mines. In the categorical analyses using 
quartiles of cumulative exposure, the results were mixed: The 
association between silica exposure and lung cancer mortality was 
statistically significant in some exposure quartiles for both metal 
mines and pottery factories (Document ID 3954, p. 2).
    Based upon these subsequent data, the ACC concluded that PAHs were 
likely present in the potteries but not in the mines (Document ID 4209, 
p. 45). OSHA believes this conclusion, although plausible, to be 
speculative. What is known is that the potteries that were excluded had 
a higher average level of PAHs, and that a significant association 
between cumulative silica exposure and lung cancer mortality remained 
in the included potteries even after the analysis was separated by 
potteries and mines. However, the association was less clear in the 
metal mines.
    The ACC also raised concerns about the silicosis status of lung 
cancer cases in the Liu cohort, asserting that some workers may not 
have had post-employment radiography given that social health insurance 
only recently began to pay for it. As such, the ACC asserted that some 
workers who developed lung cancer post-employment may have also had 
undiagnosed silicosis (Document ID 4209, pp. 49-50). OSHA acknowledges 
the limitations of the study, as with any retrospective study, but also 
notes that no evidence was put forth to indicate that workers with 
silicosis were misclassified in the study as workers without silicosis. 
Further, Dr. Goldsmith testified that the method used by Liu et al. for 
excluding workers with silicosis (x-ray findings) was ``very eminently 
reasonable,'' given that the only foolproof means of proving the 
absence of silicosis--autopsy--was not available for this particular 
cohort (Document ID 3577, Tr. 874-875).
    Thus, OSHA concludes that the Liu et al. (2013) study preliminarily 
suggests

[[Page 16333]]

that silicosis is not required for the development of lung cancer; 
however, no one study will settle the question of the role of silicosis 
in the carcinogenicity of crystalline silica. As acknowledged by Dr. 
Cox, the Agency did not rely upon the Liu et al. (2013) study in its 
preliminary or final QRA (Document ID 2307, Attachment 4, p. 37).
    Overall, after giving lengthy consideration to all evidence in the 
record regarding whether silicosis is a necessary precursor to the 
development of lung cancer, including the Liu study, the NIOSH 
testimony, and the mechanistic evidence for the carcinogenicity of 
crystalline silica discussed in Section V.H, Mechanisms of Silica-
Induced Adverse Health Effects, OSHA concludes that the mediating role 
of silicosis in the development of lung cancer is not ``apparent,'' as 
suggested by Dr. Morfeld and the ACC (Document ID 2307, Attachment 2, 
p. 16). As such, OSHA continues to believe that substantial evidence 
supports the Agency's decision to consider lung cancer as a separate, 
independent health endpoint in its risk analysis. The Agency also notes 
that even if lung cancer does not occur in the absence of silicosis, 
the record strongly supports the conclusion that workers exposed to 
respirable crystalline silica would still be at risk of developing lung 
cancer as a result of their exposure because silicosis can develop from 
average and cumulative exposures below the levels allowed at the 
previous PEL (see Section V.I, Comments and Responses Concerning 
Thresholds for Silica-Related Diseases.)
3. Additional Studies
    Stakeholders also suggested several additional studies that they 
believe OSHA should include in its QRA on lung cancer. The AFS 
commented that OSHA's Preliminary QRA overlooked a 2003 report by the 
Health and Safety Executive (HSE, Document ID 1057), asserting that 
over 40 percent of the references cited by HSE were omitted in OSHA's 
review (Document ID 4035, p. 2). OSHA disagrees with this assessment of 
overlooking the report, noting that the Agency reviewed and referenced 
the HSE report in its Review of Health Effects Literature and 
Preliminary QRA (Document ID 1711, p. 77). As discussed in Section V.C, 
Summary of the Review of Health Effects Literature and Preliminary QRA, 
OSHA used a weight-of-evidence approach to evaluate the scientific 
studies in the literature to determine their overall quality. In so 
doing, OSHA thoroughly reviewed approximately 60 published, peer-
reviewed primary epidemiological studies covering more than 30 
occupational cohorts in over a dozen industrial sectors, as well as the 
IARC pooled study and several meta-analyses (Document ID 1711, pp. 75-
172).
    The AFS also submitted a 2011 review of 30 foundry epidemiology 
studies by the Industrial Industries Advisory Council (IIAC) and noted 
that only 7 of those 30 studies were included in OSHA's Review of 
Health Effects Literature and Preliminary QRA (Document ID 2379, p. 
24). AFS wrote:

    The PQRA largely dismisses the foundry epidemiology studies, 
based on assertions of positive confounding. However, a study 
showing that there is no adverse effect despite a positive 
confounder is not only still relevant to the question, but should be 
more persuasive than a study without positive confounders because 
the data then show that even with an additive risk, there is no 
increase in effect at the reported exposure levels (Document ID 
2379, p. 24).

    In response to this comment, OSHA gathered the remaining 23 foundry 
studies cited in the submitted report and placed them in the rulemaking 
docket during the post-hearing comment period. OSHA notes, in the first 
instance, that most of these studies were not designed to study the 
effects of silica exposure on foundry workers, and did not even attempt 
to do so; rather, their purpose was to examine lung cancer mortality 
and/or morbidity in foundry work, which involves many toxic and 
otherwise harmful substances besides silica. Therefore, OSHA would 
likely be unable to suitably use these studies as a basis for a 
quantitative risk assessment regarding respirable crystalline silica by 
itself.
    With respect to AFS's assertions of studies showing ``no adverse 
effect,'' OSHA notes that the summary section of the IIAC review 
report, submitted as evidence by AFS, stated that, ``The cohort 
mortality studies and two morbidity studies suggest an increased risk 
of lung cancer in foundry workers when considered overall, but do not 
support a doubling of risk. . . . Findings in the case-control studies, 
the majority of which adjust for the effects of smoking . . . tend to 
support those of the cohort studies'' (Document ID 3991, p. 5). As 
such, this review of 30 foundry epidemiology studies showed an 
increased excess risk of lung cancer from foundry work; the fact that 
the excess risk was not increased by a factor of two is irrelevant to 
the current proceedings. The factor of two appears to be used by the 
IIAC in determining whether monetary benefits should be paid to foundry 
workers in Great Britain and is completely unrelated to OSHA's 
statutory requirements for determining whether workers exposed to 
silica are at a significant risk of material impairment of health. 
Given that excess lung cancer was observed in many of these studies, 
OSHA rejects the AFS's assertion that, even with positive confounding, 
there was no increase in adverse effect (i.e., lung cancer).
    OSHA also notes that the IIAC's finding of an elevated risk of lung 
cancer in foundries is not surprising. As Dr. Mirer stated during his 
testimony, IARC categorized foundry work as Group 1, carcinogenic to 
humans, in 1987 based on observed lung cancer (Document ID 2257, 
Attachment 3, p. 5). IARC reaffirmed its Group 1 classification for 
foundry work in 2012 (Document ID 4130). However, as noted by OSHA in 
its Review of Health Effects Literature, the foundry epidemiology 
studies were profoundly confounded by the presence of exposures to 
other carcinogens, including PAHs, aromatic amines, and metals 
(Document ID 1711, p. 264). Because of this confounding, as well as the 
fact that most of these studies did not specifically study the effects 
of silica exposure on foundry workers, OSHA has decided not to include 
them in its QRA.
    The ACC likewise cited several individual studies that it believed 
found no relationship between silica exposure and lung cancer risk 
(Document ID 2307, Attachment A, pp. 33-35). These included studies by: 
(1) Yu et al. (2007), which found no consistent exposure-response 
relationship between silica exposure and lung cancer death in workers 
with silicosis in Hong Kong (Document ID 3872); (2) Chen et al. (2007), 
which found, as mentioned in relation to the Liu et al. (2013) study, 
no relationship between silica exposure and lung cancer after adjusting 
for confounders in a study of Chinese tungsten miners, tin miners, 
iron-copper miners, and pottery workers (Document ID 1469); (3) Birk et 
al. (2009), which found the standardized mortality ratio (SMR) for lung 
cancer was not elevated in a subgroup of men who worked in areas of 
German porcelain plants with the highest likely silica exposures 
(Document ID 1468); (4) Mundt et al. (2011), which found, in a 
subsequent analysis of the German porcelain industry, that cumulative 
silica exposure was not associated with lung cancer mortality, 
mortality from kidney cancer, or any other cause of death other than 
silicosis (Document ID 1478); and (5) Westberg et al. (2013), which 
found that cumulative silica exposure was not associated with lung 
cancer morbidity (Document ID 4054).

[[Page 16334]]

    Briefly, Chen et al. (2007) examined a cohort of male workers in 29 
Chinese mines and factories, and initially found a significant trend 
between cumulative silica exposure and lung cancer mortality in pottery 
workers and tin miners; this trend was no longer significant after 
adjustment for occupational confounders (carcinogenic PAHs in 
potteries, arsenic in tin mines) (Document ID 1469, pp. 320, 323-324). 
On the contrary, Liu et al. (2013) demonstrated a statistically 
significant association between cumulative silica exposure and lung 
cancer mortality after excluding mines and factories with confounding 
exposures (article included in Document ID 2340). As noted previously, 
there are questions of how confounding exposures to radon, PAHs, and 
arsenic were handled in both the Chen et al. (2007) and Liu et al. 
(2013) studies. One important difference between the two studies, 
however, was the follow-up time. While Chen et al. (2007) had follow-up 
to 1994 and identified 511 lung cancer deaths in a cohort of 47,108 
workers (Document ID 1469, pp. 321-322), Liu et al. (2013) had follow-
up to 2003 and identified 546 lung cancer deaths in a cohort of 34,018 
workers (article included in Document ID 2340, pp. 2-4).
    OSHA discussed the Birk et al. (2009, Document ID 1468) and Mundt 
et al. (2011, Document ID 1478) studies of the German porcelain 
industry in its Supplemental Literature Review, noting several 
limitations that are applicable to both studies and might preclude the 
conclusion that there was no association between silica exposure and 
lung cancer (Document ID 1711, Attachment 1, pp. 6-12). One such 
limitation was the mean age of subjects--35 years--at the start of 
follow-up, making this a relatively young cohort in which to observe 
lung cancer. The mean follow-up period of 19 years per subject was also 
a limitation, given the long latency for lung cancer and the young age 
of the cohort at the start of follow-up; only 9.2 percent of the cohort 
was deceased by the end of the follow-up period. OSHA noted that Mundt 
et al. (2011) acknowledged that additional follow-up of the cohort may 
be valuable (Document ID 1711, Attachment 1, pp. 10-11; 1478, p. 288). 
In addition, Mundt et al. (2011) had only 74 male lung cancer deaths, 
some of whom had possible or probable prior silica exposure that could 
have resulted in cumulative exposure misclassification (Document ID 
1478, pp. 285, 288). The authors also reported statistically 
significantly elevated lung cancer hazard ratios for some categories of 
average silica exposure, but did not present any trend analysis data 
(Document ID 1478, p. 285). It also does not appear that Mundt et al. 
performed any lagged analyses for lung cancer to account for the 
latency period of lung cancer.
    Following the ACC's citation of the Yu et al. (2007) and Westberg 
et al. (2013) studies in its pre-hearing comments, OSHA obtained and 
reviewed these studies, and added them to the rulemaking docket 
(Document ID 3872; 4054). Yu et al. (2007) followed a cohort of 2,789 
workers in Hong Kong diagnosed with silicosis between 1981 and 1998. 
The average follow-up time was 9 years, with 30.6 percent of the cohort 
deceased when the study ended in 1999. The SMR for lung cancer was not 
statistically significantly elevated following indirect adjustment for 
cigarette smoking; similarly, the authors did not find a significant 
exposure-response relationship between cumulative silica exposure and 
lung cancer mortality (Document ID 3872). Westberg et al. (2013) 
studied a group of 3,045 male Swedish foundry workers to determine lung 
cancer incidence and morbidity. Although the lung cancer incidence was 
statistically significantly elevated, the authors did not find a 
significant exposure-response relationship with cumulative quartz 
exposure (Document ID 4054, p. 499).
    Regarding these studies, OSHA notes that the Westberg et al. (2013) 
study, like other foundry studies, is confounded by other carcinogenic 
substances present in foundries, including, as the authors pointed out, 
phenol, formaldehyde, furfuryl alcohols, PAHs, carbon black, 
isocyanates, and asbestos (Document ID 4054, p. 499). The Yu et al. 
(2007) study had an average follow-up period of only 9 years (Document 
ID 3872, p. 1058, Table 1), which is a short follow-up period when 
considering the latency period for the development of cancer. In 
addition, the Yu et al. study (2007), as described in the earlier Tse 
et al. (2007) study, used a job exposure matrix developed from expert 
opinion to assign estimated past levels of silica exposure to 
individuals based on self-reported work history; changes in exposure 
intensity with calendar year were not considered because of limited 
data (Document ID 3841, p. 88; 3872, p. 1057). OSHA notes that this 
exposure estimation may have included considerable misclassification 
due to inaccuracies in self-reported work history, the use of expert 
opinion to estimate past exposure levels rather than actual 
measurements for the subjects under study, and the failure to 
incorporate any changes in exposure levels over calendar time into the 
exposure estimates. Although these exposure estimates were used in an 
analysis that found a significant exposure-response for NMRD mortality 
among workers with silicosis (Tse et al., 2007, Document ID 3841), an 
exposure-response for lung cancer mortality may not be as strong and 
may be harder to detect, requiring more accurate exposure information. 
OSHA also notes that NMRD mortality is likely to be a competing cause 
of death with lung cancer, such that some workers may have died from 
NMRD before developing lung cancer. The workers with silicosis in this 
study also had high exposures (mean cumulative exposure of 10.89 mg/
m\3\-yrs) (Document ID 3872, p. 1058), possibly making it difficult to 
detect an exposure-response for lung cancer when exposures are 
relatively homogenous and high. Selection effects would have been 
extreme in these highly-exposed workers, whose all-cause mortality was 
double what would be expected (853 deaths observed, 406 expected) in 
the general population of males in Hong Kong and whose respiratory 
disease mortality was an astounding six times the expected level (445 
deaths observed, 75 expected) (Document ID 3872, p. 1059).
    OSHA acknowledges that not every study reaches the same results and 
conclusions. This is typically true in epidemiology, as there are 
different cohorts, measurements, study designs, and analytical methods, 
among other factors. As a result, scientists critically examine the 
studies, both individually and overall, in the body of literature to 
draw weight-of-evidence conclusions. IARC noted, with respect to its 
1997 carcinogenicity determination:

    [N]ot all studies reviewed demonstrated an excess of cancer of 
the lung and, given the wide range of populations and exposure 
circumstances studied, some non-uniformity of results had been 
expected. However, overall, the epidemiological findings at the time 
supported an association between cancer of the lung and inhaled 
crystalline silica ([alpha]-quartz and cristobalite) resulting from 
occupational exposure (Document ID 1473, p. 370).

    Given IARC's re-affirmation of this finding in 2012, OSHA does not 
believe that the individual studies mentioned above fundamentally 
change the weight of evidence in the body of literature supporting the 
carcinogenicity of crystalline silica. The best available evidence in 
the rulemaking record continues to indicate that exposure to respirable 
crystalline silica causes lung cancer. OSHA acknowledges, however, that 
there is some uncertainty with respect to the exact magnitude of the

[[Page 16335]]

lung cancer risk, as each of the key studies relied upon provides 
slightly different risk estimates, as indicated in Table VI-1.
    Further, the ACC focused extensively on and advocated for a study 
by Vacek et al. (2011) that found no significant association between 
respirable silica exposure and lung cancer mortality in a cohort of 
Vermont granite workers (Document ID 1486, pp. 75-81). Included in the 
rulemaking docket are the peer-reviewed published version of the study 
(Document ID 1486) and the earlier Final Report to the ACC, whose 
Crystalline Silica Panel funded the study (Document ID 2307, Attachment 
6), as well as comments from two of the authors of Vacek et al. (2011) 
responding to OSHA's treatment of the study in its Supplemental 
Literature Review (Document ID 1804). The ACC stated:

    Perhaps of most interest and relevance for present purposes--
because the cohort has been studied so extensively in the past and 
because the present PEL is based indirectly on experience in the 
Vermont granite industry--is the mortality study of Vermont granite 
workers published in 2011. While the Vermont granite workers cohort 
has been studied on a number of previous occasions, this is the most 
comprehensive mortality study of Vermont granite workers to date 
(Document ID 2307, Attachment A, p. 36).

    The ACC criticized OSHA for rejecting the Vacek et al. (2011) study 
in its Supplemental Literature Review and instead relying upon the 
Attfield and Costello (2004, Document ID 0284) study of Vermont granite 
workers (Document ID 2307, Attachment A, pp. 36-47; 4209, pp. 34-36). 
The ACC asserted several differences between the studies. First, while 
Attfield and Costello had 5,414 workers (201 lung cancer deaths) in the 
cohort, Vacek et al. had 7,052 workers (356 lung cancer deaths) as they 
extended the follow-up period by 10 years to 2004. Vacek et al. also 
claimed to have more complete mortality data, finding that ``162 
workers, whom Attfield assumed were alive in 1994, had died before that 
time and some decades earlier'' (Document ID 2307, Attachment A, p. 
38). In addition, Vacek et al. used exposure measurements and raw data 
not used by Attfield and Costello; for example, Vacek et al. used 
pension records and interviews from other studies to account for gaps 
in employment and changes in jobs, while Attfield and Costello assumed 
that a person remained in the same job between chest x-rays at the 
Vermont Department of Industrial Health surveillance program. Different 
conversion factors to estimate gravimetric concentrations from particle 
count data were also used: Attfield and Costello used a factor of 10 
mppcf = 75 [micro]g/m\3\ while Vacek et al. used a factor of 10 mppcf = 
100 [micro]g/m\3\ (Document ID 2307, Attachment A, pp. 36-39; 1804, p. 
3). OSHA notes that this discrepancy in gravimetric conversion factors 
should not affect the detection of an exposure-response relationship, 
as all exposures would differ by a constant factor.
    The ACC also pointed out that Attfield and Costello's exposure 
estimate for sandblasters was 60 [micro]g/m\3\ prior to 1940, 50 
[micro]g/m\3\ from 1940-1950, and 40 [micro]g/m\3\ after 1950, 
maintaining these numbers were too low compared to Vacek et al.'s 
estimates of 240, 160, and 70 [micro]g/m\3\, respectively (Document ID 
2307, Attachment A, p. 39; 1486, p. 313). Attfield and Costello took 
these estimates for sand blasters from the Davis et al. (1983, Document 
ID 0999) study, discussed in detail below; the estimates were based on 
six published industrial hygiene measurement studies.
    Lastly, the ACC posited that Attfield and Costello inappropriately 
excluded the highest exposure group, stating:

    Vacek et al. used all their data in evaluating potential E-R 
[exposure-response] trends with increasing exposure. Attfield and 
Costello did not. Instead, on a post hoc basis, they excluded the 
highest exposure category from their analysis when they discovered 
that the E-R trend for lung cancer was not significant if that group 
was included (even though the trends for non-malignant respiratory 
diseases were significant when all the data were used). This is an 
example of both data selection bias and confirmation bias (Document 
ID 2307, Attachment A, p. 40).

    Based upon these assertions, the ACC concluded, ``In sum, when 
judged without a result-oriented confirmation bias, the larger, more 
recent, more comprehensive, and more detailed study by Vacek et al. 
(2011) must be deemed to supersede Attfield and Costello (2004) as the 
basis for evaluating potential silica-related lung cancer risks in the 
Vermont granite industry'' (Document ID 2307, Attachment A, p. 41).
    OSHA initially discussed some issues surrounding the Vacek et al. 
(2011) study in its Supplemental Literature Review (Document ID 1711, 
Attachment 1, pp. 2-5). Specifically, OSHA noted that (1) the 
cumulative exposure quintiles used in the Vacek et al. (2011) analysis 
were higher than the values used in the Attfield and Costello (2004) 
analysis; (2) the regression models used in the Vacek et al. (2011) 
study exhibited signs of uncontrolled confounding, as workers in the 
second lowest cumulative exposure stratum in the models (except for 
silicosis) exhibited a lower risk than those in the lowest stratum, 
while all outcomes (except NMRD) in the highest exposure stratum showed 
a decline in the odds ratio (a measure of the association between 
silica exposure and health outcome) compared to the next lower stratum; 
and (3) Vacek et al. (2011) found a statistically significant excess of 
lung cancer (SMR = 1.37, with almost 100 excess lung cancer deaths) in 
the cohort when compared to U.S. white males (Document ID 1486, p. 
315). Regarding the excess lung cancer deaths, although they were 
unable to obtain information on smoking for many of the cohort members, 
Vacek et al. suggested that the elevated SMR for lung cancer was due, 
at least in part, to the differences between the smoking habits of the 
cohort and reference populations (Document ID 1486, p. 317). OSHA noted 
that although the SMR for other NMRD was elevated, there was no 
significant SMR elevation for other smoking-associated diseases, 
including cancers of the digestive organs, larynx, and bladder, as well 
as bronchitis, emphysema, and asthma (Document ID 1711, Attachment 1, 
p. 5). Elevated SMRs for these diseases would be expected if workers in 
the study population smoked more than those in the reference 
population; in fact, for all heart disease, the mortality in the study 
population (SMR = 0.89) was statistically significantly lower than the 
reference population (Document ID 1486, p. 315). These data do not 
support Vacek et al.'s assertion that smoking was responsible for the 
increased lung cancer SMR in the cohort. In addition, Davis et al. 
(1983) noted that granite shed workers employed during the 1970's 
smoked only slightly more than U.S. white males (Document ID 0999, p. 
717). OSHA also pointed out that the SMR may have been understated, as 
Vacek et al. did not account for a healthy worker effect (HWE).
    The ACC did not agree with OSHA's review of the Vacek et al. study, 
noting that OSHA ``rejects Vacek et al. (2011) on grounds that are 
confusing and unfounded'' (Document ID 2307, Attachment A, p. 41). The 
ACC argued that the quintiles of cumulative exposure used by Vacek et 
al. were not higher than typical values for lung cancer, and that OSHA, 
in its Supplemental Literature Review, compared the Vacek et al. 
quintiles of cumulative exposure for silicosis with the Attfield and 
Costello groups used for both silicosis and lung cancer (Document ID 
2307, Attachment A, pp. 41-42). OSHA acknowledges this discrepancy and, 
given that Vacek et al.

[[Page 16336]]

used quintiles of cumulative exposure that differed for each health 
endpoint, agrees that the quintiles for lung cancer used by Vacek et 
al. were not appreciably higher than the exposure groups used by 
Attfield and Costello, though the Agency recognizes that there may be 
alternative explanations for the patterns observed in the Vacek et al. 
data. Regarding uncontrolled confounding, the ACC stated that ``The 
Vermont granite worker cohort, after all, supposedly is free of 
confounding exposures,'' (Document ID 2307, Attachment A, p. 43 (citing 
Attfield and Costello, 2004, 0284)). Vacek et al. also pointed out that 
although the odds ratios for the second lowest exposure stratums were 
lower than those for the lowest categories for each of the diseases, 
they were not statistically significantly lower (Document ID 1804, pp. 
1-2).
    Although OSHA notes that this latter phenomenon, in which the odds 
ratio for the second lowest exposure stratum is lower than that for the 
lowest stratum, is commonly observed and often attributable to some 
form of selection confounding, the Agency recognizes that there may be 
alternative explanations for the patterns observed in the Vacek et al. 
data. One such explanation for the decreased odds ratios in the highest 
exposure group is potential attenuation resulting from a HWE.
    The HWE, as defined by Stayner et al. (2003), has two components: 
(1) A healthy initial hire effect, in which bias is ``introduced by the 
initial selection of workers healthy enough to work . . . and the use 
of general population rates for the comparison group, which includes 
people who are not healthy enough to work,'' and (2) a healthy worker 
survivor effect, referring ``to the tendency of workers with ill health 
to drop from the workforce and the effect this dropout may have on 
exposure-response relationships in which cumulative exposure is the 
measure of interest'' (Document ID 1484, p. 318). Thus, the healthy 
initial hire effect occurs in the scenario in which the death rate in a 
worker group is compared to that in the general population; because the 
general population has many people who are sick, the death rate for 
workers may be lower, such that a direct comparison of the two death 
rates results in a bias. The healthy worker survivor effect occurs in 
the scenario in which less healthy workers transfer out of certain jobs 
into less labor-intensive jobs due to decreased physical fitness or 
illness, or leave the workforce early due to exposure-related illness 
prior to the start of follow-up in the study. As a result, the 
healthier workers accumulate the highest exposures such that the risk 
of disease at higher exposures may appear to be constant or decrease.
    OSHA disagrees with the ACC's statement that ``the possibility of a 
potential HWE in this cohort could not have affected the E-R analyses'' 
in Vacek et al. (2011) (Document ID 2307, Attachment A, p. 46), and 
with the similar statement by study authors Pamela Vacek, Ph.D. and 
Peter Callas, Ph.D., both of the University of Vermont, who asserted 
that the HWE could not have impacted their exposure-response analyses 
``because they were not based on an external reference population'' 
(Document ID 1804, p. 2). This explanation only considers one component 
of the HWE, the healthy initial hire effect. An internal control 
analysis, such as that performed by Vacek et al., will generally 
minimize the healthy initial hire effect but does not address the 
healthy worker survivor effect (see Document ID 1484, p. 318 (Stayner 
et al. (2003)). Thus, the statement by the ACC that there could be no 
HWE in the internal case control analysis of Vacek et al. (2011) is 
incorrect, as it considered only the healthy initial hire effect and 
not the healthy worker survivor bias.
    In contrast, Attfield and Costello's stated rationale for excluding 
the highest exposure group is related to the healthy worker survivor 
effect:

    We do know that this group is distinctive in entering the cohort 
with substantial exposures--83% had worked for 20 years or more in 
the high dust levels prevalent prior to controls. They were, 
therefore, a highly selected healthy worker group. A further reason 
may be that in the days when tuberculosis and silicosis were the 
main health concerns in these workers, lung cancer may have been 
obscured in this group as a cause of death in some cases'' (Document 
ID 0284, p. 136).

    Support for Attfield and Costello's reasoning is provided by a 
study by Applebaum et al. (2007), which re-analyzed the data from the 
Attfield and Costello (2004) paper and concluded that there was a 
healthy worker survivor effect present (study cited by Vacek et al., 
2009, Document ID 2307, Attachment 6, p. 3). Applebaum et al. (2007) 
split the cohort of Vermont granite workers into two groups: (1) Those 
that began working before the start of the study follow-up, i.e., 
prevalent hires; and (2) those that began working after the start of 
the study follow-up, i.e., incident hires. The rationale for splitting 
the cohort into these two groups was to examine if a healthy worker 
survivor effect was more likely in the prevalent hire group, as this 
group would be affected by workers that were more susceptible to health 
effects and left the industry workforce prior to the start of the study 
follow-up (Applebaum et al., 2007, pp. 681-682). Using spline models to 
examine exposure-response relationships without forcing a particular 
form (e.g., linear, linear-quadratic) on the observed data, the authors 
found that the inclusion of prevalent hires in the analysis weakened 
the association between cumulative silica exposure and lung cancer 
because of bias from the healthy worker survivor effect. The bias can 
be reduced by including only incident hires, or keeping the date of 
hire close to the start of follow-up (Applebaum et al., 2007, pp. 685-
686). An alternative explanation for this trend offered by Applebaum et 
al. may be that, assuming that there was more measurement error in the 
older data, the prevalent hires had more exposure misclassification 
(2007, p. 686); in such a case, however, the inclusion of prevalent 
hires would still bias the results towards the null. Given the findings 
of the Applebaum et al. (2007) study, OSHA believes that Attfield and 
Costello (2004) had good reasons for removing the highest exposure 
group, which was composed mostly of prevalent workers (83 percent of 
workers in the highest exposure group had worked at least 20 years 
prior to the start of the follow-up period) (Document ID 0284, p. 136).
    Vacek et al. (2011), on the other hand, excluded 609 workers in the 
design of their study cohort due to insufficient information. However, 
the majority of the workers excluded from the cohort were incident 
hires who began work after 1950 (Document ID 2307, Attachment 6, p. 12; 
1486, p. 314). The final Vacek et al. (2011) cohort included 2,851 
prevalent hires (began employment before 1950) compared to 4,201 
incident hires (began employment in or after 1950) (Document ID 2307, 
Attachment 6, p. 12; 1486, p. 314). By composing about 40 percent of 
their cohort with prevalent hires and excluding many incident hires, 
Vacek et al. (2011) may have introduced additional healthy worker 
survivor effect bias into their study. Interestingly, Vacek et al. 
described the Applebaum et al. (2007) results in their 2009 report, 
stating, ``They [Applebaum et al.] found that decreasing the relative 
proportion of prevalent to incident hires [in the data used by Attfield 
and Costello] resulted in a stronger association between cumulative 
silica exposure and lung cancer mortality'' (Document ID

[[Page 16337]]

2307, Attachment 6, p. 3). Despite their acknowledgement of the 
Applebaum et al. (2007) findings, Vacek et al. (2011) did not conduct 
any analysis of only the incident hires, or use statistical methods to 
better determine the presence and effect of a healthy worker survivor 
effect in their study.
    The ACC also commented on Vacek et al.'s suggestion that the 
elevated SMR observed for lung cancer in the cohort (when compared to a 
reference population of U.S. white males) was due to differences in the 
smoking habits of the cohort and reference population, which OSHA 
criticized in its Supplemental Literature Review (Document ID 1486, p. 
317; 1711, Attachment 1, p. 5). The ACC stated, ``OSHA suggests that 
the lack of complete smoking data for the cohort is a problem and 
contends that smoking could not explain the elevated SMR for lung 
cancer. This criticism, as Dr. Vacek explains, is overstated, and, in 
any event, does not detract from the study's findings regarding the 
absence of an association between silica exposure and lung cancer'' 
(Document ID 2307, Attachment A, pp. 46-47; 1804, p. 2).
    Vacek et al. (2011) estimated the relative smoking prevalence in 
the cohort to be 1.35 times that in the reference population; using 
this estimated relative smoking prevalence, the authors estimated that 
``the expected number of lung cancer deaths in the cohort after 
adjusting the reference rates for smoking would be 353, yielding a 
[non-significant] SMR of 1.02'' (Document ID 1486, p. 317). OSHA notes 
that this method used by Vacek et al. to adjust the SMR for smoking 
neglects the healthy worker survivor effect (i.e., smokers may leave 
the workforce sooner than nonsmokers because smoking is a risk factor 
for poor health). Absent control for the healthy worker survivor 
effect, smoking would (and perhaps did) become a negative confounder 
because long duration--high cumulative exposure--workers would tend 
toward lower smoking attributes. The method used by Vacek et al. is 
also inconsistent with the frequently cited Axelson (1978) method, 
which is used to adjust the SMR when the exposed population has a 
higher percentage of smokers than the reference population (Checkoway 
et al. 1997, Document ID 0326; Chan et al. 2000, 0983). As a result, 
Vacek et al. (2011) likely overestimated the confounding effect of 
smoking in this cohort.
    In addition, as previously noted by OSHA, the SMRs for cancers 
largely attributable to smoking, such as those of the buccal cavity and 
pharynx (SMR = 1.01), larynx (SMR = 0.99), and esophagus (SMR = 1.15) 
were not significant in the Vacek et al. study (Document ID 1486, p. 
315; 2307, Attachment 6, p. 14). The SMR of 0.94 for bronchitis, 
emphysema, and asthma also was not significant. If smoking were truly 
responsible for the highly statistically significant SMR (1.37) 
observed for lung cancer, the SMRs for these other diseases should be 
significant as well. OSHA likewise notes that other studies have found 
that smoking does not have a substantial impact on the association 
between crystalline silica exposure and lung cancer mortality (e.g., 
Checkoway et al., 1997, Document ID 0326; Steenland et al., 2001a, 
0452, p. 781) and that crystalline silica is a risk factor for lung 
cancer independent of smoking (Kachuri et al., 2014, Document ID 3907, 
p. 138; Preller et al., 2010, 4055, p. 657).
    OSHA is also concerned about some features of the study design and 
exposure assessment in Vacek et al. (2011). Regarding the study design, 
in their nested case-control analyses, Vacek et al. sorted cases into 
risk sets based on year of birth and year of death, and then matched 
three controls to each risk set; from the data presented in Table 5 of 
the study, the actual number of controls per lung cancer case can be 
calculated as 2.64 (Document ID 1486, p. 316). Vacek et al.'s decision 
to use such a small number of controls per case was unnecessarily 
restrictive, as there were additional cohort members who could have 
been used as controls for the lung cancer deaths. Typically, if the 
relevant information is available, four or more (or all eligible) 
controls are used per case to increase study power to detect an 
association. OSHA notes that Steenland et al. (2001a), in their nested 
case-control pooled analysis, used 100 controls per case (Document ID 
0452, p. 777).
    In addition, Vacek et al. stated that for the categorical analysis, 
cut points on cumulative exposure were based on quintiles of the 
combined distribution for cases and controls (Document ID 1486, p. 
314). Therefore, there should be an approximately equal total number of 
subjects (cases plus controls) in each group (or quintile). OSHA's 
examination of Table 5 in the Vacek et al. (2011) study shows that 
there is an approximately equal distribution of subjects for all 
endpoints except lung cancer; for example, the silicosis groups each 
had 43-44 subjects, the NMRD groups each had 125-130 subjects, the 
kidney cancer groups each had 22-23 subjects, and the kidney disease 
groups each had 25 subjects. However, the lung cancer groups, ranging 
from the lowest to the highest exposure, had 325, 232, 297, 241, and 
202 subjects (Document ID 1486, p. 316). OSHA could find no explanation 
for this discrepancy in the text of the Vacek et al. (2011) study, and 
questions how the lung cancer groups were composed.
    With respect to the different job exposure matrices, OSHA has 
reason to believe that the exposure data reported in the Attfield and 
Costello study are more accurate than the data Vacek et al. used. OSHA 
is particularly concerned that Vacek et al.'s pre-1940 exposure 
estimate of 150 [micro]g/m\3\ for one job (channel bar operator) was 
much lower than Attfield and Costello's estimate, from the Davis et al. 
(1983) matrix, of 1070 [micro]g/m\3\ (Document ID 1486, p. 313; 0284, 
p. 131). As NIOSH observed in its post-hearing comments, changing the 
exposure estimate for channel bar operators could have ``major 
consequences'' on the exposure-response analysis, as the job occurred 
frequently (Document ID 4233, p. 22). NIOSH then pointed out that the 
Attfield and Costello (2004) exposure estimate for channel bar 
operators was based on multiple exposure measurements conducted by 
Davis et al. (1983), whereas Vacek et al. based their exposure estimate 
``on only three dust measurements'' in which ``only wet drilling was 
used. Thus, their study used not only very limited sampling data but 
also values that were biased towards low levels, since the samples were 
taken when water was being used to control dust,'' a practice that was 
not typically used for this occupation at the time (Document ID 4233, 
p. 22). In fact, photographs from Hosey et al. (1957) showed channel 
bar drilling in 1936 and 1937 with and without dust control; the 
caption for the photo without dust control states that the ``operator 
in background is barely visible through dust cloud'' (Document ID 4233, 
p. 24, citing 3998, Attachment 14b). As NIOSH explained,

    If there is a true [linear] relationship between exposure to 
silica dust and lung cancer mortality, classifying highly exposed 
workers incorrectly as low-exposed shifts the elevated risks to the 
low exposure range. The impact is to spuriously elevate risks at low 
exposures and lower them at high exposures, resulting in the 
exposure-response trend being flattened or even obscured. 
Ultimately, the true relationship may not be evident, or if it is, 
may be attenuated (Document ID 4233, p. 22, n. 1).

    Vacek et al. reported in their study that they conducted a 
sensitivity analysis that did not change the exposure-response 
relationship between silica exposure and lung cancer risk,

[[Page 16338]]

even when Attfield and Costello's pre-1940 exposure estimates were used 
for channel bar operators (Document ID 2340, pp. 317-318; 2307, 
Attachment 6, p. 31). Part of the problem may be the way that channel 
bar operators were defined by Vacek et al. As noted by NIOSH, ``Leyner 
driller and channel bar operator or driller are synonyms'' (Document ID 
4233, p. 22, n. 3). Attfield and Costello defined channel bar operators 
in that way, with a pre-1940 exposure estimate of 1070 [micro]g/m\3\ 
(Document ID 0284, p. 131). Vacek et al., on the contrary, assigned 
channel bar operators to a category called ``channel bar (wet)'' and 
assigned a pre-1940 exposure estimate of 150 [micro]g/m\3\ (Document ID 
2307, Attachment 6, Appendix B, pp. 7, 15). They included Leyner 
drillers under a general category called ``driller'' with a pre-1940 
exposure estimate of 1070 [micro]g/m\3\ (Document ID 2307, Attachment 
6, Appendix B, pp. 7, 15). Included in the Vacek et al. (2009) category 
of ``drillers'' were plug drillers (Document ID 2307, Attachment 6, 
Appendix B, p. 15); OSHA notes that Attfield and Costello used a lower 
pre-1940 exposure estimate of 650 [micro]g/m\3\ for plug drillers, as 
defined by Davis et al. (1983). OSHA believes that Vacek et al. 
underestimated the exposures of some channel bar operators, and 
overestimated the exposures of plug drillers, which may have 
contributed to the lack of association, and that the categorization 
used by Attfield and Costello, with the synonymous channel bar 
operators and Leyner drillers in one category, and plug drillers in a 
separate category, was more appropriate. Thus, even in Vacek et al's 
sensitivity analysis, in which they used Attfield and Costello's 
exposure estimate of 1070 [micro]g/m\3\ for channel bar operators and 
drillers, the plug drillers would still have had a higher exposure 
estimate (1070 [micro]g/m\3\ versus Attfield and Costello's 650 
[micro]g/m\3\), making the analysis different from that of Attfield and 
Costello.
    For the reasons discussed herein, OSHA has decided not to reject 
the Attfield and Costello (2004) study in favor of the Vacek et al. 
(2011) study as a basis for risk assessment. OSHA maintains that it has 
performed an objective analysis of the Attfield and Costello (2004) and 
Vacek et al. (2011) studies. OSHA agrees with some of the ACC's 
criticisms regarding the Agency's initial evaluation of the exposure 
groupings and confounding in the Vacek et al. (2011) study. OSHA is 
concerned, however, as discussed above, about several aspects of Vacek 
et al. (2011), including a potential bias from the healthy worker 
survivor effect, which was shown to exist in this cohort (see Applebaum 
et al., 2007, cited in Document ID 2307, Attachment 6, p. 3), as well 
as about job categorization that may have resulted in exposure 
misclassification for certain job categories (e.g., the synonymous 
channel bar operators and Leyner drillers). Despite its concerns with 
the Vacek et al. study, OSHA acknowledges that comprehensive studies, 
such as Attfield and Costello (2004) and Vacek et al. (2011), in the 
Vermont granite industry have shown conflicting results with respect to 
lung cancer mortality (Document ID 0284; 1486). As discussed earlier, 
conflicting results are often observed in epidemiological studies due 
to differences in study designs, analytical methods, exposure 
assessments, populations, and other factors. In addition, the exposure-
response relationship between silica and lung cancer may be easily 
obscured by bias, as crystalline silica is a comparably weaker 
carcinogen (i.e., the increase in risk per unit exposure is smaller) 
than other well-studied, more potent carcinogens such as hexavalent 
chromium (Steenland et al., 2001, Document ID 0452, p. 781). Although 
OSHA believes that the Attfield and Costello (2004) study is the most 
appropriate Vermont granite study to use in its QRA, the Agency notes 
that, even in the absence of the Attfield and Costello (2004) study, 
the risk estimates for lung cancer mortality based on other studies 
still provide substantial evidence that respirable crystalline silica 
poses a significant risk of serious health conditions to exposed 
workers.
4. Comments on Specific Studies Relied Upon by OSHA in Its QRA
a. Attfield and Costello (2004)
    As stated above, OSHA disagrees with the ACC's contention that 
Vacek et al. provides a more reliable scientific basis for estimating 
risk than Attfield and Costello. While it is true that the final risk 
estimate (54 deaths per 1,000 workers) derived from the Attfield and 
Costello study for an exposure level of 100 [micro]g/m\3\ is the 
highest when compared to the other studies, it is not true that the 
final risk estimate (22 deaths per 1,000 workers) derived from the 
Attfield and Costello study is the highest for the final rule's PEL of 
50 [micro]g/m\3\. In fact, it is within the range of risk estimates 
derived from the ToxaChemica (2004) pooled analysis of 16 to 23 deaths 
per 1,000 workers at the final PEL. Thus OSHA has decided to retain its 
reliance on the Attfield and Costello (2004) study and, again, notes 
that, even without the Attfield and Costello (2004) study, all of the 
other studies in the Final QRA demonstrate a clearly significant risk 
of lung cancer mortality (11 to 54 deaths per 1,000 workers) at an 
exposure level of 100 [micro]g/m\3\, with a reduced, albeit still 
significant, risk (5 to 23 deaths per 1,000 workers) at an exposure 
level of 50 [micro]g/m\3\ (see Table VI-1 in Section VI, Final 
Quantitative Risk Assessment and Significance of Risk). Excluding 
Attfield and Costello (2004), in other words, would not change OSHA's 
final conclusion regarding the risk of death from lung cancer.
b. Miller and MacCalman (2009)
    According to the ACC, OSHA's risk estimates based on the Miller and 
MacCalman (2009, Document ID 1306) study are ``more credible than the 
others--because [the study] involved a very large cohort and was of 
higher quality in terms of design, conduct, and detail of exposure 
measurements,'' and also adjusted for smoking histories (Document ID 
2307, Attachment A, p. 73). Although the risk estimates generated from 
the Miller and MacCalman data were the lowest of the lung cancer 
mortality estimates, the ACC next asserted that they were biased 
upwards for several reasons. First, the ACC stated that exposure 
information was lacking for cohort members after the mines closed in 
the mid-1980's, and quoted OSHA as stating, ``Not accounting for this 
exposure, if there were any, would bias the risk estimates upwards'' 
(Document ID 2307, Attachment A, p. 74 (quoting 1711, p. 289)). OSHA, 
however, does not believe there to have been additional substantial 
quartz exposures. As the study authors wrote, ``Because of the steep 
decline of the British coal industry, the opportunities for further 
extensive coal mine exposure were vanishingly small'' (Document ID 
1306, p. 11). Thus OSHA believes it to be unlikely that the risk 
estimates are biased upwards to any meaningful degree based on lack of 
exposure information at the end of the study period.
    The ACC also stated that the unrestricted smoking of cohort members 
after the closure of the mines would have resulted in risk estimates 
that were biased upwards (Document ID 2307, Attachment A, p. 74). OSHA 
has no reason to believe, nor did the ACC submit any evidence in 
support of its contention, that unrestricted smoking occurred, however, 
and notes that the authors stated that the period after the mines 
closed was one of ``greater anti-

[[Page 16339]]

smoking health promotion campaigns'' (Document ID 1306, p. 11).
    Finally, the ACC noted that Miller and MacCalman did not adjust 
significance levels for the multiple comparisons bias with respect to 
lag selection that Dr. Cox alleged affected their study (Document ID 
2307, Attachment A, p. 74). Dr. Cox claimed that trying multiple 
comparisons of alternative approaches, such as different lag periods, 
and then selecting a final choice based on the results of these 
multiple comparisons, leads to a multiple comparisons bias that could 
result in false-positive associations (Document ID 2307, Attachment 4, 
p. 28; see Section V.J, Comments and Responses Concerning Biases in Key 
Studies). He argued that the authors should have reduced the 
significance level (typically p = 0.05) at which a result is considered 
to be significant. ``Lag'' refers to the exclusion of the more recent 
years of exposure (e.g., 10-year lag, 15-year lag) to account for the 
fact that diseases like cancer often have a long latency period (i.e., 
that the cancer may not be detected until years after the initiating 
exposure, and exposures experienced shortly before detection probably 
did not contribute to the development of disease). ``Lag selection,'' 
therefore, refers to the choice of an appropriate lag period. As 
addressed later in the Section V.J, Comments and Responses Concerning 
Biases in Key Studies, OSHA does not necessarily believe such an 
adjustment of significance levels to be appropriate, based upon the 
testimony of Mr. Park of NIOSH, nor is it typically performed in the 
occupational epidemiology literature (Document ID 3579, Tr. 151-152). 
Similarly, the ACC stated that the confidence intervals are overly 
narrow because they ignore model uncertainty, and that multiple 
imputation of uncertain exposure values should have been performed 
(Document ID 2307, Attachment A, p. 75). OSHA rejects this assertion on 
the grounds that the authors used detailed exposure estimates that the 
ACC recognized raised the credibility of the study; the ACC wrote, 
regarding the study, ``it involved a very large cohort and was of 
higher quality in terms of design, conduct, and detail of exposure 
measurements'' (Document ID 2307, Attachment A, p. 73). Lastly, the ACC 
argued that an exposure threshold should have been examined (Document 
ID 2307, Attachment A, p. 75). OSHA discusses at length this issue of 
thresholds, and the difficulty in ruling them in or out at low 
exposures, in Section V.I, Comments and Responses Concerning Thresholds 
for Silica-Related Diseases.
    In summary, OSHA notes that the ACC has not provided any non-
speculative evidence to support its claims that the risk estimates 
derived from the Miller and MacCalman (2009) study are biased upwards. 
As stated in the Review of Health Effects Literature and Preliminary 
QRA, and acknowledged by the ACC (Document ID 2307, p. 73), OSHA 
believes these risk estimates to be very credible, as the study was 
based on well-defined union membership rolls with good reporting, had 
over 17,000 participants with nearly 30 years of follow-up, and had 
detailed exposure measurements of both dust and quartz, as well as 
smoking histories (Document ID 1711, pp. 288-289).
c. Steenland (2001a) and ToxaChemica (2004)
    OSHA also received several comments on the ToxaChemica (2004, 
Document ID 0469) analysis, which was based on the Steenland et al. 
(2001a, Document ID 0452) pooled analysis. First, the ACC claimed that 
there is significant heterogeneity in the exposure-response 
coefficients, derived from the individual studies. Because the risk 
estimates based on these coefficients differ by almost two orders of 
magnitude, the ACC suggested that these models are misspecified for the 
data (Document ID 2307, Attachment A, pp. 75-76). Essentially, the ACC 
claimed that the exposure-response coefficients differ too much among 
the individual studies, and asserted that it is therefore inappropriate 
to use the pooled models. Dr. Cox wrote: ``Steenland et al. did not 
address the heterogeneity, but artificially suppressed it by 
unjustifiably applying a log transformation. This is not a valid 
statistical approach for exposure estimates with substantial estimation 
errors'' (Document ID 2307, Attachment 4, p. 75). During the public 
hearing, however, Dr. Steenland explained to OSHA's satisfaction how 
the data in his study was transformed, using accepted statistical 
methods. Specifically, referring to his use of a log transformation to 
address the heterogeneity, Dr. Steenland testified:

    [I]t reduces the effect of the very highest exposures being able 
to drive an exposure-response curve because those exposures are 
often [skewed] way out--skewed to the right, because occupational 
exposure data is often log normal. With some very high exposures, 
they are sort of extreme, and that can drive your exposure-response 
curve. And you take the log, it pulls them in, and so therefore 
gives less influence to those high data points. And I think those 
high data points are often measured with more error (Document ID 
3580, Tr. 1265-1266).

    OSHA finds this testimony to be persuasive and, therefore, believes 
that Dr. Steenland's use of a log transformation to address the 
heterogeneity was appropriate. The log transformation also permits a 
better model fit when attenuation of the response is observed at high 
cumulative exposures.
    Dr. Morfeld commented that Steenland et al. did not take into 
account smoking, which could explain the observed excess lung cancer of 
20 percent (SMR = 1.2). Dr. Morfeld stated, ``Thus, lung cancer excess 
risks were demonstrated only under rather high occupational exposures 
to RCS dust, and, even then, an upward bias due to smoking and a 
necessary intermediate role for silicosis could not be ruled out'' 
(Document ID 2307, Attachment 2, p. 10). Dr. Steenland addressed the 
concern about a potential smoking bias during his testimony:

    We concluded that this positive exposure response was not likely 
due to different smoking habits between high exposed and low exposed 
workers. And the reason we did that was twofold. First, workers tend 
to smoke similar amounts regardless of their exposure level in 
general. We often worry about comparing workers to the general 
population because workers tend to smoke more than the general 
population. But, in internal analyses, we don't have this problem 
very often. When we have smoking data, we see that it is not related 
to exposure, so a priori we don't think it is likely to be a strong 
confounder in internal analyses. Secondly, a number of the studies 
we used in our pool[ed] cohort had smoking data, either for the 
whole cohort or partially. And when they took that into account, 
their results did not change. In fact, they also found that smoking 
was not related to exposure in their studies, which means that it 
won't affect the exposure-disease relationship because if it is 
going to do that, it has to differ between the high exposed and the 
low exposed, and it generally did not (Document ID 3580, Tr. 1227-
1228).

    In addition, Brown and Rushton (2009), in their review article 
submitted to the rulemaking record by Dr. Morfeld, appeared to agree 
with Dr. Steenland, stating, ``This [Steenland et al.] internal 
analysis removed the possibility of confounding by smoking'' (Document 
ID 3573, Attachment 5, p. 150). Thus, OSHA rejects Dr. Morfeld's 
assessment that the risk estimates may be biased upwards due to 
smoking.
    The ACC also commented that exposure misclassification due to 
uncertain exposure estimates in Steenland's pooled cohort could have 
created the appearance of a monotonic relationship, in which the 
response

[[Page 16340]]

increases with the exposure, even if the true response was not 
monotonic (Document ID 2307, Attachment A, p. 76). The ACC, along with 
Dr. Borak (representing the U.S. Chamber of Commerce) and others, 
likewise cited OSHA's statement from the Review of Health Effects 
Literature and Preliminary QRA, in which the Agency acknowledged that 
uncertainty in the exposure estimates that underlie each of the 10 
studies in the pooled analysis was likely to represent one of the most 
important sources of uncertainty in the risk estimates (Document ID 
1711, p. 292; 2376, p. 16). Dr. Borak also quoted Mannetje et al. 
(2002), who developed quantitative exposure data for the pooled 
analysis, as stating, ``While some measurement error certainly occurred 
in our estimates, a categorical analysis based on broad exposure groups 
should not be much affected by the resulting level of 
misclassification'' (Document ID 2376, p. 17, quoting 1090, p. 84). 
From this statement, Dr. Borak concluded that the researchers 
themselves believed the data were only adequate for ``categorical 
analyses which might lead to qualitative conclusions'' (Document ID 
2376, p. 17).
    OSHA disagrees with Dr. Borak's interpretation of the Mannetje et 
al. statement, as categorical analyses are typically quantitative in 
nature, with the data being used to draw quantitative conclusions. 
However, OSHA recognized the possibility for uncertainty in the 
exposure estimates, and it is for this reason that OSHA commissioned a 
quantitative analysis of uncertainty in Steenland's pooled study 
(ToxaChemica, 2004, Document ID 0469). This analysis suggested that 
exposure misclassification had little effect on the pooled exposure 
coefficient (and the variance around that estimate) for the lung cancer 
risk model (Document ID 1711, pp. 313-314). Given this analysis, OSHA 
also disagrees with the ACC's statement that ``it is virtually certain 
that substantial exposure estimation error infused the pooled analysis, 
resulting in exposure misclassification that would create a false 
appearance of a monotonically increasing exposure-response even where 
none exists'' (Document ID 2307, Attachment A, p. 78). OSHA notes that 
this statement is not supported with any evidence from the Steenland et 
al. (2001) study. In addition, as discussed at length in Section V.K, 
Comments and Responses Concerning Exposure Estimation Error and 
ToxaChemica's Uncertainty Analysis, exposure estimation error can also 
bias results towards the null (weaken or obscure the exposure-response 
relationship) (Document ID 3580, Tr. 1266-67; 3576, Tr. 358-359; 3574, 
p. 21). Other criticisms from the ACC concerning alleged modeling 
errors and biases in the Steenland study and the alleged threshold for 
the health effects of silica exposure are discussed generally in 
Section V.J, Comments and Responses Concerning Biases in Key Studies, 
and Section V.I, Comments and Responses Concerning Thresholds for 
Silica-Related Diseases. Dr. Cox's and Dr. Morfeld's criticisms of the 
uncertainty analysis performed by Toxachemica are addressed in Section 
V.K, Comments and Responses Concerning Exposure Estimation Error and 
ToxaChemica's Uncertainty Analysis. For the reasons stated in those 
sections, OSHA is unpersuaded by these criticisms.
    The ACC concluded:

    For all these reasons, the pooled analysis by Steenland et al. 
(2001) does not yield credible or reliable estimates of silica-
related lung cancer risk. But, even if risk estimates based on 
Steenland et al. (2001) were not so problematic, that study would 
not demonstrate that reducing the PEL from 0.1 mg/m\3\ [100 
[micro]g/m\3\] to 0.05 mg/m\3\ [50 [micro]g/m\3\] will result in a 
substantial reduction in the risk of lung cancer (Document ID 2307, 
Attachment A, p. 81).

    The ACC then discussed the ToxaChemica report (2004), which the ACC 
claimed shows that ``under the spline model (which the authors prefer 
over the log cumulative model because of biological plausibility)'' 
reducing the PEL from 100 [micro]g/m\3\ to 50 [micro]g/m\3\ would 
negligibly reduce the excess risk of lung cancer mortality from 0.017 
(17/1,000) to 0.016 (16/1,000), ``risk values that are 
indistinguishable given the overlapping confidence limits of the two 
estimates'' (Document ID 2307, Attachment A, p. 81). In addition, the 
ACC noted that the excess risk at 150 [micro]g/m\3\ and 250 [micro]g/
m\3\ in the spline model is the same as the excess risk at 50 [micro]g/
m\3\, while that at 200 [micro]g/m\3\ is lower. ``Estimates of lung 
cancer risk in the neighborhood of the current general industry PEL are 
hugely uncertain--with the data suggesting that a greater reduction in 
lung cancer risk could be achieved by doubling the PEL to 200 [micro]g/
m\3\ than by cutting it in half to a level of 50 [micro]g/m\3\'' 
(Document ID 2307, Attachment A, pp. 81-82).
    OSHA notes that these risk estimates cited by the ACC were the 
original estimates for the spline model provided to OSHA by ToxaChemica 
in its 2004 report (Document ID 0469). These are not the risk estimates 
used by OSHA. Instead, to estimate the risks published in this final 
rule, the Agency used the exposure-response coefficients from the study 
in an updated life table analysis using background all-cause mortality 
and lung cancer mortality rates from 2006 and 2011, respectively. The 
risk estimates using the 2011 background data are the most updated 
numbers with which to make the comparisons ACC has suggested. With the 
2011 background data, the estimated excess risk is 20 deaths per 1,000 
workers at 100 [micro]g/m\3\, and 16 deaths per 1,000 workers at 50 
[micro]g/m\3\, a reduction of 4 deaths. OSHA's estimated excess risk at 
250 [micro]g/m\3\ is 24 deaths per 1,000 workers, an increase in 8 
deaths when compared to 50 [micro]g/m\3\. Thus it is not the case, as 
ACC suggested, that increasing the PEL would cause a reduction in lung 
cancer mortality risk.
    In addition, the linear spline model employed by Steenland et al. 
(2001) was only one of three models used by OSHA to estimate 
quantitative risks from the pooled analysis. OSHA also used the log-
linear model with log cumulative exposure as well as the linear model 
with log cumulative exposure (see Section VI, Final Quantitative Risk 
Assessment and Significance of Risk). OSHA notes that all three models 
indicated a reduction in risk when comparing an exposure level of 100 
[micro]g/m\3\ to 50 [micro]g/m\3\.
    In summary, OSHA disagrees with the ACC's assertion that the 
Steenland et al. pooled analysis does not yield credible risk estimates 
for lung cancer mortality. Dr. Morfeld's assertion that the risk 
estimates were biased upwards due to smoking is quite unlikely to be 
true, given that the study was an internal (worker to worker) analysis. 
The ACC's claim that exposure estimation error resulted in false 
exposure-response relationships was not supported by any actual data; 
as discussed in Section V.K, Comments and Responses Concerning Exposure 
Estimation Error and ToxaChemica's Uncertainty Analysis, exposure 
estimation error can also bias results towards the null (weaken or 
obscure the exposure-response relationship) (Document ID 3580, Tr. 
1266-67; 3576, Tr. 358-359; 3574, p. 21). For these reasons, OSHA 
rejects the ACC's claims that the Steenland study of lung cancer 
mortality does not yield credible risk estimates. Rather, based upon 
its review, OSHA believes this pooled analysis to be of high quality. 
As Dr. Steenland testified during the informal public hearings, this 
pooled analysis, with its more than 60,000 workers and 1,000 lung 
cancer deaths, involved ``a rich dataset with high statistical power to 
see anything, if there was anything to see'' (Document ID 3580, Tr. 
1227). In fact, OSHA believes the Steenland et al. (2001a) study to be 
among the best available studies in the peer-reviewed literature on the 
topic of

[[Page 16341]]

silica exposure and its relationship to lung cancer mortality.
d. Rice et al. (2001)
    The ACC also commented on the Rice et al. (2001, Document ID 1118) 
study of diatomaceous earth workers, which found a significant risk of 
lung cancer mortality that increased with cumulative silica exposure in 
a cohort of diatomaceous earth workers. The ACC claimed that it had a 
high likelihood of exposure misclassification. Dr. Cox contended that 
the practice of ``[a]ssigning each worker a single estimated cumulative 
exposure based on estimated mean values produces biased results and 
artificially narrow confidence intervals (and hence excess false-
positive associations)'' (Document ID 2307, Attachment 4, p. 76). OSHA 
notes that Rice et al. (2001) described the exposure estimation 
procedure in their paper. There were more than 6,000 measurements of 
dust exposure taken from 1948-1988; particle count data were converted 
to gravimetric data using linear regression modeling. Cumulative 
exposures to respirable crystalline silica were then estimated for each 
worker using detailed employment records (Document ID 1118, p. 39). 
OSHA concludes it is highly unlikely that the exposure estimates are 
biased to such an extent, as Dr. Cox suggests, that they would produce 
false-positive associations.
    The ACC also noted that the mean crystalline silica exposure in the 
diatomaceous earth worker cohort was 290 [mu]g/m\3\, approximately 
three times the former PEL for general industry (Document ID 2307, 
Attachment A, p. 83). OSHA, however, believes that the cumulative 
respirable crystalline silica dust concentration is the metric of 
concern here, as that is what was used in the regression models. The 
mean cumulative respirable crystalline silica dust concentration in the 
study was 2.16 mg/m\3\-yrs, which is a very realistic cumulative 
exposure for many workers (Document ID 1118, p. 39).
    The ACC also stated that the results of the Rice study were 
confounded by smoking and possibly asbestos exposure (Document ID 2307, 
Attachment A, p. 83). OSHA previously addressed the possible 
confounding in this cohort in its Review of Health Effects Literature 
and Preliminary QRA (Document ID 1711, pp. 139-143). Rice et al. (2001) 
used the same cohort originally reported on by Checkoway et al. (1993, 
Document ID 0324; 1996, 0325; 1997, 0326). The Rice study discussed the 
smoking confounding analysis performed by Checkoway et al. (1997), in 
which the Axelson method (1978) was used to make a worst case estimate 
(assuming 20 times greater lung cancer risk in smokers compared to non-
smokers) and indirectly adjust the relative risk (RR) estimates for 
lung cancer for differences in smoking rates (Document ID 1118, pp. 40-
41). With exposures in the Checkoway study lagged 15 years to account 
for the latency period, the worst case effect was to reduce the RR for 
lung cancer in the highest exposure group from 2.15 to 1.67. Checkoway 
et al. concluded that the association between respirable silica 
exposure and lung cancer was unlikely to be confounded by cigarette 
exposure (Document ID 0326, pp. 684, 687). Regarding confounding by 
asbestos exposure, Rice et al. (2001) stated:

    Checkoway et al. found no evidence that exposure to asbestos 
accounted for the observed association between mortality from lung 
cancer and cumulative exposure to silica. Our analyses of their data 
also found no evidence of confounding by asbestos in the Poisson 
regression or Cox's proportional hazards models regardless of lag 
period; therefore, exposure to asbestos was not included in the 
models presented in this paper (Document ID 1118, p. 41).

    Based upon these analyses, OSHA rejects the ACC's unsupported 
assertion that the results of Rice et al. (2001) were confounded by 
smoking and asbestos exposure.
    Lastly, Dr. Cox asserted that there were several biases in Rice et 
al. (2001), including multiple-testing bias from testing multiple lag 
periods, exposure groupings, and model forms; model specification bias; 
and a lack of model diagnostics (Document ID 2307, Attachment 4, pp. 
63-64, 77). OSHA addressed these issues generally in Section V.J, 
Comments and Responses Concerning Biases in Key Studies, and rejects 
these assertions for the same reasons. OSHA also discussed regression 
diagnostics at length in the same section. In summary, despite the 
criticisms directed at the Rice et al. study by the ACC, OSHA continues 
to believe that the quantitative exposure-response analysis by Rice et 
al. (2001) is of high quality and appropriate for inclusion in the QRA 
(Document ID 1711, p. 143).
e. Hughes et al. (2001)
    The ACC, through the comments of Dr. Cox, presented a similar 
critique of the study of North American industrial sand workers by 
Hughes et al. (2001, Document ID 1060). This study found a 
statistically significant association (increased odds ratios) between 
lung cancer mortality and cumulative silica exposure as well as average 
silica concentration (Document ID 1060). In this study, according to 
Dr. Cox, ``The selected model form guarantees a monotonic exposure-
response relation, independent of the data. Model uncertainty and 
errors in exposure estimates have both been ignored, so the slope 
estimate from Hughes et al. (2001), as well as the resulting excess 
risk estimates, are likely to be biased and erroneous'' (Document ID 
2307, Attachment 4, p. 85). The ACC also noted that this cohort had 
incomplete smoking information, with the proportion of ``ever smokers'' 
significantly higher in cases than in controls. In addition, the ACC 
asserted that asbestos exposure may have also occurred, as three death 
certificates listed mesothelioma as the cause of death (Document ID 
2307, Attachment A, pp. 85-86).
    OSHA discussed the Hughes et al. (2001, Document ID 1060) study in 
its Review of Health Effects Literature and Preliminary QRA, 
highlighting as strengths the individual job, exposure, and smoking 
histories that were available (Document ID 1711, p. 285). Exposure 
levels over time were estimated via a job exposure matrix constructed 
by Rando et al. (2001, Document ID 0415) utilizing substantial exposure 
data, including 14,249 respirable dust and silica samples taken from 
1974 to 1998 in nine plants (Document ID 1711, pp. 88, 124-128; 1060, 
202). Smoking data were collected from medical records supplemented by 
information from next of kin or living subjects for 91 percent of cases 
and controls (Document ID 1060, p. 202). OSHA believes these smoking 
histories allowed the authors to adequately control for confounding by 
smoking in their analyses. Regarding the three death certificates 
listing mesothelioma, McDonald et al. (2001) explained that two were 
for workers not included in the case/control study because they were 
hired at or after age 40 with less than 10 years of work time; the 
third was for a worker hired at age 19 who then accumulated 32 years of 
experience in maintenance jobs (Document ID 1091, p. 195). As such, 
OSHA does not believe it likely that asbestos exposure was a large 
source of confounding in typical industrial sand operations in this 
study. OSHA also notes that the positive findings of this study were 
consistent with those of other studies of workers in this cohort, 
including Steenland and Sanderson (2001, Document ID 0455) and McDonald 
et al. (2005, Document ID 1092).
    The ACC also noted that there was no consistent correlation in 
Hughes et al. (2001) between employment duration

[[Page 16342]]

and lung cancer risk (Document ID 2307, Attachment A, p. 86), with Dr. 
Cox suggesting that model specification error was to blame (Document ID 
2307, Attachment 4, p. 86). OSHA believes that cumulative exposure is a 
more appropriate metric for determining risk than is duration of 
exposure because the cumulative exposure metric considers both the 
duration and intensity of exposure. For example, some workers may have 
been employed for a very long duration with low exposures, whereas 
others may have been employed for a short duration but with high 
exposures; both groups could have similar cumulative exposures.
    In summary, OSHA considers the Hughes et al. (2001) study to be of 
high enough quality to provide risk estimates for excess lung cancer 
from silica exposure, as the study is unlikely to be substantially 
confounded. For these reasons, the Agency finds the assertion that the 
risk estimates based on this study are erroneous to be unconvincing.
    Overall, regarding all of the studies upon which OSHA relied in its 
Preliminary QRA, the ACC concluded, ``In sum, none of the studies on 
which OSHA relies is inconsistent with a concentration threshold above 
100 [mu]g/m\3\ for any risk of silica-related lung cancer; none 
demonstrates an increased lung cancer risk in the absence of silicosis; 
and none provides a sound basis for estimating lung cancer risks at RCS 
[respirable crystalline silica] exposure levels of 100 [mu]g/m\3\ and 
below'' (Document ID 2307, Attachment A, p. 87).
    OSHA is not persuaded that the evidence presented by the ACC 
supports these conclusions. On the contrary, as OSHA discussed in the 
Section V.I, Comments and Responses Concerning Thresholds for Silica-
Related Diseases, demonstrating the absence of a threshold is not a 
feasible scientific pursuit, and some models produce threshold 
estimates well below the PELs. Similarly, the ACC has not put forward 
any study that has proven that silicosis must be a precursor for lung 
cancer and, as discussed in Section V.H, Mechanisms of Silica-Induced 
Adverse Health Effects, some studies have shown genotoxic mechanisms by 
which exposure to crystalline silica may lead to lung cancer. The 
strong epidemiological evidence for carcinogenicity, supported by 
evidence from experimental animal and mechanistic studies, allowed IARC 
to conclude on multiple occasions that respirable crystalline silica is 
a Group I carcinogen. OSHA places great weight on this conclusion given 
IARC's authority and standing in the international scientific 
community. In addition, all of the lung cancer studies relied upon by 
OSHA used models that allow for the estimation of lung cancer risks at 
crystalline silica exposure levels of 100 [mu]g/m\3\ and below. OSHA 
believes these studies (Steenland et al., 2001a, Document ID 0452, as 
re-analyzed in ToxaChemica, 2004, 0469; Rice et al., 2001, 1118; 
Attfield and Costello, 2004, 0284; Hughes et al., 2001, 1060; and 
Miller and MacCalman, 2009, 1306) are of high quality and contain well-
supported findings. Thus, OSHA continues to rely upon these studies for 
deriving quantitative risk estimates in its QRA and continues to 
believe that workers exposed to respirable crystalline silica at levels 
at or near the previous and new PELs are faced with a significant risk 
of dying from lung cancer. As such, the Agency believes it would be 
irresponsible as a scientific matter, and inconsistent with its 
statutory obligations to issue standards based on the best available 
evidence after conducting an extensive rulemaking, to retain the 
regulatory status quo.

G. Comments and Responses Concerning Renal Disease Mortality

    OSHA estimated quantitative risks for renal disease mortality 
(Document ID 1711, pp. 314-316) using data from a pooled analysis of 
renal disease, conducted by Steenland et al. (2002a, Document ID 0448). 
As illustrated in Table VI-1, the lifetime renal disease mortality risk 
estimate for 45 years of exposure to the previous general industry PEL 
(100 [mu]g/m\3\ respirable crystalline silica) is 39 deaths per 1,000 
workers. However, for the final PEL (50 [mu]g/m\3\), it is 32 deaths 
per 1,000 workers. Although OSHA acknowledges that there are 
considerably less data for renal disease mortality, and thus the risk 
findings based on them are less robust than those for silicosis, lung 
cancer, and non-malignant respiratory disease (NMRD) mortality, the 
Agency believes the renal disease risk findings are based on credible 
data. Indeed, the Steenland et al. pooled analysis had a large number 
of workers from three cohorts with sufficient exposure data, and 
exposure matrices for the three cohorts had been used in previous 
studies that showed positive exposure-response trends for silicosis 
morbidity or mortality, thus tending to validate the underlying 
exposure and work history data (see Document ID 1711, pp. 215-216). 
Nevertheless, OSHA received comments that were critical of its risk 
estimates for renal disease mortality. Based upon its review of the 
best available evidence, OSHA finds that these comments do not alter 
its overall conclusions on renal disease mortality. In addition, OSHA 
notes that even if the risk of renal disease mortality is discounted, 
there would remain clearly significant risks of lung cancer mortality, 
silicosis and NMRD mortality, and silicosis morbidity, with more robust 
risk estimates based upon a larger amount of data from numerous studies 
(see Table VI-1).
    OSHA received several comments from the ACC regarding the Agency's 
quantitative risk estimates for renal disease mortality. Specifically, 
the ACC argued that: (1) The pooled study (Steenland et al., 2002a, 
Document ID 0448) that OSHA relied upon did not provide sufficient data 
to estimate quantitative risks; (2) the individual studies included in 
the pooled study had several limitations; and (3) most epidemiological 
studies have not demonstrated a statistically significant association 
between silica exposure and renal disease mortality (Document ID 2307, 
Attachment A, pp. 139-157; 4209, pp. 92-96). As explained below, and as 
stated above, although the Agency acknowledges there is greater 
uncertainty in the risk estimates related to renal disease than other 
silica-related diseases, the best available evidence is of sufficient 
quality to quantify the risk of renal disease in the final risk 
assessment.
1. Pooled Study
    Some commenters expressed concern about the Steenland et al. 
(2002a, Document ID 0448) pooled study of renal disease mortality, 
which OSHA and its contractor, ToxaChemica, used to calculate 
quantitative risk estimates. Specifically, the ACC questioned why the 
analysis only used three studies (Homestake, North Dakota gold miners, 
Steenland and Brown, 1995a, Document ID 0450; U.S. industrial sand 
workers, Steenland et al., 2001b, Document ID 0456; Vermont granite 
workers, Costello and Graham, 1988, Document ID 0991) out of the ten 
originally used in the pooled study of lung cancer mortality (Steenland 
et al., 2001a, Document ID 0452). Peter Morfeld, Dr. rer. medic., 
representing the ACC, wrote in his written testimony that although 
Steenland et al. (2002a, Document ID 0448) indicated that the three 
studies were selected because they were the only ones to have 
information on multiple cause mortality, all 10 studies had information 
on renal disease as an underlying cause of death (Document ID 2308, 
Attachment 4, pp. 24-25). Since ToxaChemica focused on underlying cause 
results in their discussion, Dr. Morfeld argued that not having used 
all

[[Page 16343]]

10 studies in the pooled analysis ``raises a suspicion of study 
selection bias'' (Document ID 2308, Attachment 4, pp. 24-25).
    OSHA finds this assertion of study selection bias by the ACC and 
Dr. Morfeld to be unpersuasive because Steenland et al.'s explanation 
(2002a) for including only three studies in the pooled analysis was 
sound. The authors reported in their pooled study that both underlying 
cause and multiple cause mortality were available for only three 
cohorts of silica-exposed workers, and ``multiple cause (any mention on 
the death certificate) was of particular interest because renal disease 
is often listed on death certificates without being the underlying 
cause'' (Document ID 0448, p. 5). The authors likewise cited a study 
(Steenland et al., 1992), indicating that the ratio of chronic renal 
disease mortality shown anywhere on a U.S. death certificate versus 
being shown as an underlying cause is 4.75 (Document ID 0453, Table 2, 
pp. 860-861). Indeed, in their pooled analysis of renal disease 
mortality, Steenland et al. noted that there were 51 renal disease 
deaths when using underlying cause, but 204 when using multiple cause 
mortality (Document ID 0448, p. 5). As renal disease is a serious 
disabling disease, the use of multiple cause mortality gives a much 
better sense of the burden of excess disease than does the use of 
underlying cause of death as an endpoint. As such, Steenland et al. 
calculated odds ratios by quartile of cumulative silica exposure for 
renal disease in a nested case-control analysis that considered any 
mention of renal disease on the death certificate as well as underlying 
cause. For multiple-cause mortality, the exposure-response trend was 
statistically significant for both cumulative exposure (p = 0.004) and 
log cumulative exposure (p = 0.0002); whereas for underlying cause 
mortality, the trend was statistically significant only for log 
cumulative exposure (p = 0.03) (Document ID 1711, p. 315). Thus, OSHA 
believes that Steenland et al. (2002a, Document ID 0448) were justified 
in including only the three cohorts with all-cause mortality in their 
pooled analysis.
    Concern was also expressed about the model selection in the pooled 
analysis. Dr. Morfeld noted that a statistically significant 
association between exposure to crystalline silica and renal disease 
mortality was only found in the underlying cause analysis in which the 
model was logged (p = 0.03) (Document ID 2308, Attachment 4, p. 25). 
Dr. Morfeld commented, ``The authors stated that the log-model fit 
better, but evidence was not given (e.g., information criteria), and it 
is unclear whether the results are robust to other transformations'' 
(Document ID 2308, Attachment 4, p. 25).
    OSHA disagrees with this criticism because a log transformation of 
the cumulative exposure metric is reasonable, given that exposure 
variables are often lognormally distributed in epidemiological studies, 
as discussed in Section V.J, Comments and Responses Concerning Biases 
in Key Studies. Also, while it is true that Steenland et al. (2002a) 
only found a statistically significant association in the continuous 
underlying cause analysis when the cumulative exposure metric was 
logged (p = 0.03), OSHA notes that the authors also found a 
statistically significant association in the highest quartile of 
unlogged cumulative silica exposure (1.67 + mg/m\3\-yr) in the 
categorical underlying cause analysis (95% confidence interval: 1.31-
11.76) (Document ID 0448, Table 2, p. 7). Thus, for the highest 
cumulative exposures, there was a significant association with renal 
disease mortality even without a log transformation of the exposure 
metric. Dr. Morfeld also failed to mention that Steenland et al. 
(2002a) found statistically significant associations in the continuous 
analyses (for both untransformed and log-transformed cumulative 
exposure) using any mention of renal disease on the death certificate, 
which adds weight to the study's findings that exposure to respirable 
crystalline silica is associated with renal disease mortality (Document 
ID 0448, Table 2, p. 7). In light of this, OSHA concludes that Dr. 
Morfeld's criticism of the pooled analysis is without merit.
    The ACC also noted that the authors of this study, Drs. Kyle 
Steenland and Scott Bartell, acknowledged the limitations of the data 
in their 2004 ToxaChemica report to OSHA. Specifically, in reference to 
the 51 renal deaths (underlying cause) and 23 renal cases in the pooled 
study, Drs. Steenland and Bartell wrote, ``This amount of data is 
insufficient to provide robust estimates of risk'' (Document ID 2307, 
Attachment A, p. 139, citing 0469, p. 27). Given this acknowledgement, 
the ACC concluded that OSHA's inclusion of the renal disease mortality 
risk estimates in the significant risk determination and calculation of 
expected benefits was speculative (Document ID 2307, Attachment A, pp. 
139-140). During the hearing, Dr. Steenland further explained, ``I 
think there is pretty good evidence that silica causes renal disease. I 
just think that there is not as big a database as there is for lung 
cancer and silicosis. And so there is more uncertainty'' (Document ID 
3580, Tr. 1245). OSHA agrees with Dr. Steenland and acknowledges, as it 
did in its Review of Health Effects Literature and Preliminary QRA 
(Document ID 1711, p. 357), that its quantitative risk estimates for 
renal disease mortality have more uncertainty and are less robust than 
those for the other health effects examined (i.e., lung cancer 
mortality, silicosis and NMRD mortality, and silicosis morbidity). 
However, OSHA disagrees with the ACC's suggestion that the Agency's 
renal disease risk estimates are ``rank speculation'' (Document ID 
4209, pp. 95-96), as these estimates are based on the best available 
evidence in the form of a published, peer-reviewed pooled analysis 
(Steenland et al. 2002a, Document ID 0448) that uses sound 
epidemiological and statistical methods. Thus, OSHA believes that it is 
appropriate to present the risk estimates along with the associated 
uncertainty estimate (e.g., 95% confidence intervals) (see Document ID 
1711, p. 316).
2. Individual Studies in the Pooled Study
    The ACC also identified limitations in each of the three 
epidemiological studies included in the Steenland et al. (2002a, 
Document ID 0448) pooled study. First, with respect to the Steenland 
and Brown (1995a, Document ID 0450) study of North Dakota gold miners, 
the ACC noted there was a significantly elevated standardized mortality 
ratio (SMR) for chronic renal disease only in the men hired prior to 
1930. It noted that there were no silica exposure measurement data 
available for this early time period, such that Steenland and Brown 
(1995a, Document ID 0450) instead estimated a median exposure (150 
[mu]g/m\3\) that was seven times higher for men hired prior to 1930, 
versus men hired after 1950 (20 [mu]g/m\3\) (Document ID 2307, 
Attachment A, p. 147). The ACC maintained that these exposure estimates 
were likely to be understated and not credible, while also suggesting 
``the existence of an average exposure threshold >=150 [mu]g/m\3\ for 
any risk of silica-related renal disease mortality'' (Document ID 2307, 
Attachment A, p. 147).
    OSHA finds the ACC's suggestion of a threshold to be unpersuasive, 
as the ACC provided no analysis to indicate a threshold in this study. 
OSHA addresses the Steenland and Brown (1995a, Document ID 0450) 
exposure assessment in Section V.D, Comments and Responses Concerning 
Silicosis and Non-Malignant Respiratory Disease Mortality and 
Morbidity. The ACC also

[[Page 16344]]

ignored the alternative explanation, that elevated chronic renal 
disease mortality may have only been seen in the workers hired prior to 
1930 because they had a higher cumulative exposure than workers hired 
later, not because there was necessarily a threshold.
    The ACC had a similar criticism of the Steenland et al. (2001b, 
Document ID 0456) study of North American industrial sand workers. The 
ACC posited that the exposure estimates were highly uncertain and 
likely to be understated (Document ID 2307, Attachment A, p. 149). The 
ACC noted that these exposure estimates, developed by Sanderson et al. 
(2000, Document ID 0429), were considerably lower than those developed 
by Rando et al. (2001, Document ID 0415) for another study of North 
American industrial sand workers (Document ID 2307, Attachment A, p. 
149). After discussing several differences between these two exposure 
assessments, the ACC pointed to OSHA's discussion in the lung cancer 
section of the preamble to the Proposed Rule (78 FR at 56302) in which 
the Agency acknowledged that McDonald et al. (2001, Document ID 1091), 
Hughes et al. (2001, Document ID 1060) and Rando et al. (2001, Document 
ID 0415) had access to smoking histories, plant records, and exposure 
measurements that allowed for the development of a job exposure matrix, 
while Steenland and Sanderson (2001, Document ID 0455) had limited 
access to plant facilities, less detailed historic exposure data, and 
used MSHA enforcement records for estimates of recent exposure 
(Document ID 2307, Attachment A, pp. 149-151). The ACC then noted that 
the McDonald et al. study (2005, Document ID 1092), using the Rando et 
al. (2001, Document ID 0415) exposure assessment, found no association 
between end-stage renal disease or renal cancer and cumulative silica 
exposure (Document ID 2307, Attachment A, pp. 149, 152).
    The ACC also noted that, based on underlying cause of death, the 
SMR for acute renal death in the Steenland et al. (2001b, Document ID 
0456) study was not significant (95% confidence interval: 0.70-9.86), 
and the SMR for chronic renal disease was barely significant (95% 
confidence interval: 1.06-4.08) (Document ID 2307, Attachment A, p. 
151). In light of this, the ACC maintained that Steenland et al. based 
their exposure-response analyses on multiple-cause mortality data, 
using all deaths with any mention of renal disease on the death 
certificate even if it was not listed as the underlying cause. The ACC 
asserted that ``only the underlying cause data involve actual deaths 
from renal disease'' (Document ID 2307, Attachment A, p. 152).
    OSHA does not find this criticism persuasive. For regulatory 
purposes, multiple-cause mortality data is, if anything, more relevant 
because renal disease constitutes the type of material impairment of 
health that the Agency is authorized to protect against through 
regulation regardless of whether it is determined to be the underlying 
cause of a worker's death. Moreover, the discrepancy in the renal 
disease mortality findings is a moot point, as only the model in the 
pooled study with renal disease as an underlying cause was used to 
estimate risks in the Preliminary QRA (Document ID 1711, p. 316). In 
any event, OSHA notes an important difference between the Steenland et 
al. study (2001b, Document ID 0456) and the McDonald study (2005, 
Document ID 1092): They did not look at the same cohort of North 
American industrial sand workers. Steenland et al. (2001b) examined a 
cohort of 4,626 workers from 18 plants; the average year of first 
employment was 1967, with follow-up through 1996 (Document ID 0456, pp. 
406-408). McDonald et al. (2005) examined a cohort of 2,452 workers 
employed between 1940 and 1979 at eight plants, with follow-up through 
2000 (Document ID 1092, p. 368). Although there was overlap of about 
six plants in the studies (Document ID 1711, p. 127), these were 
clearly two fairly different cohorts of industrial sand workers. These 
differences in the cohorts might explain the discrepancy in the 
studies' results. In addition, OSHA notes that McDonald et al. (2005, 
Document ID 1092) observed statistically significant excess mortality 
from nephritis/nephrosis in their study that was not explained by the 
findings of their silica exposure-response analyses (Document ID 1092, 
p. 369).
    The ACC further argued that the Steenland et al. (2002a, Document 
ID 0448) pooled study is inferior to the Vacek et al. (2011, Document 
ID 2340) study of Vermont granite workers, which found no association 
between cumulative silica exposure and mortality from either kidney 
cancer or non-malignant kidney disease and which it contended has 
better mortality and exposure data (Document ID 2307, Attachment A, p. 
154) (citing Vacek et al. (2011, Document ID 2340). In particular, it 
argued that the Vacek et al. study is more reliable for this purpose 
than the unpublished Attfield and Costello data (2004, Document ID 
0285) on Vermont granite workers, which Steenland et al. relied on in 
finding an association between silica exposure and renal disease.
    OSHA notes that Steenland et al. acknowledged in their pooled study 
that that unpublished data had not undergone peer review (Document ID 
0448, p. 5). Despite this limitation, OSHA is also unpersuaded that the 
Vacek et al. study, although it observed no increased kidney disease 
mortality (Document ID 2340, Table 3, p. 315), negates Steenland et 
al.'s overall conclusions. OSHA discussed several substantial 
differences between these two studies in Section V.F, Comments and 
Responses Concerning Lung Cancer Mortality.
3. Additional Studies
    The ACC also submitted to the record several additional studies 
that did not show a statistically significant association between 
exposure to crystalline silica and renal disease mortality. These 
included the aforementioned studies by McDonald et al. (2005, Document 
ID 1092) and Vacek et al. (2011, Document ID 2340), as well as studies 
by Davis et al. (1983, Document ID 0999), Koskela et al. (1987, 
Document ID 0363), Cherry et al. (2012, article included in Document ID 
2340), Birk et al. (2009, Document ID 1468), Mundt et al. (2011, 
Document ID 1478), Steenland et al. (2002b, Document ID 0454), Rosenman 
et al. (2000, Document ID 1120), and Calvert et al. (2003, Document ID 
0309) (Document ID 2307, Attachment A, pp. 140-145). In light of its 
assertions on the limitations of the three studies in the pooled 
analysis, and because the three studies ``run counter to a larger 
number of studies in which a causal association between silica exposure 
and renal disease was not found,'' the ACC concluded that ``the three 
studies relied on by OSHA do not provide a reliable or supportable 
basis for projecting any risk of renal disease mortality from silica 
exposure'' (Document ID 4209, p. 94). Similarly, the AFS argued that 
renal disease was only ``found in a couple of selected studies and not 
observed in most others,'' including no foundry studies (Document ID 
2379, Attachment 1, pp. 1-3).
    In light of the analysis contained in the Review of Health Effects 
Literature and Preliminary QRA, and OSHA's confirmation of its 
preliminary findings through examination of the record, OSHA finds 
these claims to be lacking in merit (Document ID 1711, pp. 211-229). In 
the Review of Health Effects Literature and Preliminary QRA, OSHA 
presented a comprehensive analysis of several studies that showed an 
association between crystalline silica

[[Page 16345]]

and renal disease, as well as discussing other studies that did not 
(Document ID 1711, pp. 211-229). Based upon its overall analysis of the 
literature, including the negative studies, OSHA concluded that there 
was substantial evidence suggesting an association between exposure to 
crystalline silica and increased risks of renal disease. This 
conclusion was supported by a number of case reports and 
epidemiological studies that found statistically significant 
associations between occupational exposure to silica dust and chronic 
renal disease (Calvert et al., 1997, Document ID 0976), subclinical 
renal changes (Ng et al., 1992c, Document ID 0386), end-stage renal 
disease morbidity (Steenland et al., 1990, Document ID 1125), end-stage 
renal disease incidence (Steenland et al. 2001b, Document ID 0456), 
chronic renal disease mortality (Steenland et al., 2002a, 0448), and 
granulomatosis with polyangitis (Nuyts et al., 1995, Document ID 0397). 
In other findings, silica-exposed individuals, both with and without 
silicosis, had an increased prevalence of abnormal renal function (Hotz 
et al., 1995, Document ID 0361), and renal effects were reported to 
persist after cessation of silica exposure (Ng et al., 1992c, Document 
ID 0386). While the mechanism of causation is presently unknown, 
possible mechanisms suggested for silica-induced renal disease included 
a direct toxic effect on the kidney, deposition in the kidney of immune 
complexes (IgA) following silica-related pulmonary inflammation, or an 
autoimmune mechanism (Calvert et al., 1997, Document ID 0976; Gregorini 
et al., 1993, 1032).
    From this review of the studies on renal disease, OSHA concluded 
that there were considerably less data, and thus the findings based on 
them were less robust, than the data available for silicosis and NMRD 
mortality, lung cancer mortality, or silicosis morbidity. Nevertheless, 
OSHA concluded that the Steenland et al. (2002a, Document ID 0448) 
pooled study had a large number of workers and validated exposure 
information, such that it was sufficient to provide useful estimates of 
risk of renal disease mortality. With regard to the additional negative 
studies presented by the ACC, OSHA notes that it discussed the Birk et 
al. (2009, Document ID 1468) and Mundt et al. (2011, Document ID 1478) 
studies in the Supplemental Literature Review of the Review of Health 
Effects Literature and Preliminary QRA, noting the short follow-up 
period as a limitation, which makes it unlikely to observe the presence 
of renal disease (Document ID 1711, Supplement, pp. 6-12). OSHA 
likewise discussed the Vacek et al. (2011, Document ID 2340) study 
earlier in this section, and notes that Cherry et al. reported a 
statistically significant excess of non-malignant renal disease 
mortality in the cohort for the period 1985-2008, with an unexplained 
cause (2012, p. 151, article included in Document ID 2340). Although 
these latter two studies did not find a significant association between 
silica exposure and renal disease mortality, OSHA does not believe that 
they substantially change its conclusions on renal disease mortality 
from the Preliminary QRA, given the number of positive studies 
presented and the limitations of those two studies.
    Thus, OSHA recognizes that the renal risk estimates are less robust 
and have more uncertainty than those for the other health endpoints for 
which there is a stronger case for causality (i.e., lung cancer 
mortality, silicosis and NMRD mortality, and silicosis morbidity). But, 
for the reasons stated above, OSHA believes that the evidence 
supporting causality regarding renal risk outweighs the evidence 
casting doubt on that conclusion. Scientific certainty is not the legal 
standard under which OSHA acts. OSHA is setting the standard based upon 
the clearly significant risks of lung cancer mortality, silicosis and 
NMRD mortality, silicosis morbidity, and renal disease mortality at the 
previous PELs; even if the risk of renal disease mortality is 
discounted, the conclusion would not change that regulation is needed 
to reduce the significant risk of material impairment of health (see 
Society of the Plastics Industry, Inc. v. OSHA, 509 F.2d 1301, 1308 (2d 
Cir. 1975)).

H. Mechanisms of Silica-Induced Adverse Health Effects

    In this section, OSHA describes the mechanisms by which silica 
exposure may cause silica-related health effects, and responds to 
comments criticizing the Agency's analysis on this topic. In the 
proposal as well as this final rule, OSHA relied principally on 
epidemiological studies to establish the adverse health effects of 
silica exposure. The Agency also, however, reviewed animal studies (in 
vivo and in vitro) as well as in vitro human studies that provide 
information about the mechanisms by which respirable crystalline silica 
causes such effects, particularly silicosis and lung cancer. OSHA's 
review of this material can be found in the Review of Health Effects 
Literature and Preliminary Quantitative Risk Assessment (QRA), which 
provided background and support for the proposed rule (Document ID 
1711, pp. 229-261).
    As described in the Review of Health Effects Literature, OSHA 
performed an extensive evaluation of the scientific literature 
pertaining to inhalation of respirable crystalline silica (Document ID 
1711, pp. 7-265). Due to the lack of evidence of health hazards from 
dermal or oral exposure, the Agency focused solely on the studies 
addressing the inhalation hazards of respirable crystalline silica. 
OSHA determined, based on the best available scientific information, 
that several cellular events, such as cytotoxicity (i.e., cellular 
damage), oxidative stress, genotoxicity (i.e., damage to cellular DNA), 
cellular proliferation, and inflammation can contribute to a range of 
neoplastic (i.e., tumor-forming) and non-neoplastic health effects in 
the lung. While the exact mechanisms have yet to be fully elucidated, 
they are likely initiated by damage to lung cells from interaction 
directly with the silica particle itself or through silica particle 
activation of alveolar macrophages following phagocytosis (i.e., 
engulfing particulate matter in the lung for the purpose of removing or 
destroying foreign particles). The crystalline structure and unusually 
reactive surface properties of the silica particle appear to cause the 
early cellular effects. Silicosis and lung cancer share common features 
that arise from these early cellular interactions but OSHA, in its 
Review of Health Effects Literature and Preliminary QRA, 
``preliminarily conclude[d] that available animal and in vitro studies 
have not conclusively demonstrated that silicosis is a prerequisite for 
lung cancer in silica-exposed individuals'' (Document ID 1711, p. 259). 
Although the health effects associated with inhalation of respirable 
crystalline silica are seen primarily in the lung, other observed 
health effects include kidney and immune dysfunctions.
    Below, OSHA reviews the record evidence and responds to comments it 
received on the mechanisms underlying respirable crystalline silica-
induced lung cancer and silicosis. The Agency also addresses comments 
regarding the use of animal studies to characterize adverse health 
effects in humans caused by exposure to respirable crystalline silica.
1. Mechanisms for Silica-Related Health Effects
    In 2012, IARC reevaluated the available scientific information 
regarding respirable crystalline silica and lung cancer and reaffirmed 
that crystalline silica is carcinogenic to

[[Page 16346]]

humans, i.e., a Group 1 carcinogen (Document ID 1473, p. 396). OSHA's 
review of all the evidence now in the rulemaking record, including the 
results of IARC's reevaluation, indicates that silica may lead to 
increased risk of lung cancer in humans by a multistage process that 
involves a combination of genotoxic (i.e., causing damage to cellular 
DNA) and non-genotoxic (i.e., not involving damage to DNA) mechanisms. 
Respirable crystalline silica may cause genotoxicity as a result of 
reactive oxygen species (ROS) produced by activated alveolar 
macrophages and other lung cells exposed to crystalline silica 
particles during phagocytosis. ROS have been shown to damage DNA in 
human lung cells in vitro (see Document ID 1711, pp. 236-239). This 
genotoxic mechanism is believed to contribute to neoplastic 
transformation and silica-induced carcinogenesis. ROS is not only 
produced during the early cellular interaction with crystalline silica 
but also produced by PMNs (polymorphonuclear leukocytes) and 
lymphocytes recruited during the inflammatory response to crystalline 
silica. In addition to genotoxicity contributed by ROS, it is also 
plausible that reactive molecules on the surface of crystalline silica 
itself may bind directly to DNA and result in genotoxicity (Document ID 
1711, p. 236). It should be noted that the mechanistic evidence 
summarized above suggests that crystalline silica may cause early 
genotoxic events that are independent of the advanced chronic 
inflammatory response and silicosis (Document ID 1473, pp. 391-392).
    Non-genotoxic mechanisms are also believed to contribute to the 
lung cancer caused by respirable crystalline silica. Phagocytic 
activation as well as silica-induced cytotoxicity trigger release of 
the aforementioned ROS, cytokines (e.g., TNF[alpha]), and growth 
factors (see Document ID 1711, pp. 233-235). These agents are able to 
cause cellular proliferation, loss of cell cycle regulation, activation 
of oncogenes (genes that have the potential to cause cancer), and 
inhibition of tumor suppressor genes, all of which are non-genotoxic 
mechanisms known to promote the carcinogenic process. It is plausible 
that these mechanisms may be involved in silica-induced tumorigenesis. 
The biopersistence and cytotoxic nature of crystalline silica leads to 
a cycle of cell death (i.e., cytotoxicity), activation of alveolar 
macrophages, recruitment of inflammatory cells (e.g., PMNs, 
leukocytes), and continual release of the non-genotoxic mediators 
(i.e., ROS, cytokines) able to promote carcinogenesis. The non-
genotoxic mechanisms caused by early cellular responses (e.g., 
phagocytic activation, cytotoxicity) are regarded, along with 
genotoxicity, as important potential pathways that lead to the 
development of tumors (Document ID 1711, pp. 232-239; 1473, pp. 394-
396).
    The same non-genotoxic processes that may cause lung cancer from 
respirable crystalline silica exposure are also believed to lead to 
chronic inflammation, lung scarring, fibrotic lesions, and eventually 
silicosis. This would occur when inflammatory cells move from the 
alveolar space through the interstitium of the lung as part of the 
clearance process. In the interstitium, respirable crystalline silica-
laden cells--macrophages and neutrophils--release ROS and TNF-[alpha], 
as well as other cytokines, stimulating the proliferation of 
fibroblasts (i.e., the major lung cell type in silicosis). 
Proliferating fibroblasts deposit collagen and connective tissue, 
inducing the typical scarring that is observed with silicosis. 
Alternatively, alveolar epithelial cells containing respirable 
crystalline silica die and may be replaced by fibroblasts due to 
necrosis of the epithelium. This allows for uninhibited growth of 
fibroblasts and formation of connective tissue where scarring 
proliferates (i.e., silicosis). As scarring increases, there is a 
reduction in lung elasticity concomitant with a reduction of the lung 
surface area capable of gas exchange, thus reducing pulmonary function 
and making breathing more difficult (Document ID 0314; 0315). It should 
be noted that silicosis involves many of the same mechanisms that occur 
during the early cellular interaction with crystalline silica. 
Therefore, it is plausible that development of silicosis may also 
potentially contribute to silica-induced lung cancer. However, the 
relative contributions of silicosis-dependent and silicosis-independent 
pathways are not known.
    Although it is clear that exposure to respirable crystalline silica 
increases the risk of lung cancer in exposed workers (see Section VI, 
Final Quantitative Risk Assessment and Significance of Risk), some 
commenters claimed that such exposure cannot cause lung cancer 
independently of silicosis (i.e., only those workers who already have 
silicosis can get lung cancer) (Document ID 2307, Attachment A, p. 53). 
This claim is inconsistent with the credible scientific evidence 
presented above that genotoxic and non-genotoxic mechanisms triggered 
by early cellular responses to crystalline silica prior to development 
of silicosis may contribute to crystalline silica-induced 
carcinogenesis. OSHA finds, based on its review of all the evidence in 
the rulemaking record, that workers without silicosis, as well as those 
with silicosis, are at risk of lung cancer if regularly exposed to 
respirable crystalline silica at levels permitted under the previous 
and new PELs. The Agency also emphasizes that, regardless of the 
mechanism by which respirable crystalline silica exposure increases 
lung cancer risk, the fact remains that workers exposed to respirable 
crystalline silica continue to be diagnosed with lung cancer at a 
higher rate than the general population. Therefore, as discussed in 
section VI, Final Quantitative Risk Assessment and Significance of 
Risk, OSHA has met its burden of proving that workers exposed to 
previously allowed levels of respirable crystalline silica are at 
significant risk, by one or more of these mechanisms, of serious and 
life-threatening health effects, including both silicosis and lung 
cancer.
2. Relevance of Animal Models to Humans
    Animal data has been used for decades to evaluate hazards and make 
inferences regarding causal relationships between human health effects 
and exposure to toxic substances. The National Academies of Science has 
endorsed the use of well-conducted animal studies to support hazard 
evaluation in the risk assessment process (Document ID 4052, p. 81) and 
OSHA's policy has been to rely on such studies when regulating 
carcinogens. In the case of respirable crystalline silica, OSHA has 
used evidence from animal studies, along with human epidemiology and 
other relevant information, to establish that occupational exposure is 
associated with silicosis, lung cancer, and other non-malignant 
respiratory diseases, as well as renal and autoimmune effects (Document 
ID 1711, pp. 261-266). Exposure to various forms of respirable 
crystalline silica by inhalation and intratracheal instillation has 
consistently caused lung cancer in rats (IARC, 1997, Document ID 1062, 
pp. 150-163). These results led IARC and NTP to conclude that there is 
sufficient evidence in experimental animals to demonstrate the 
carcinogenicity of crystalline silica in the form of quartz dust. IARC 
also concluded that there is sufficient evidence in human studies for 
the carcinogenicity of crystalline silica in the form of quartz or 
cristobalite.

[[Page 16347]]

    In its pre-hearing comments and post-hearing brief, the ACC noted 
that increased lung cancer risks from exposure to respirable 
crystalline silica have not been found in animal species other than 
rats, and questioned the relevance of the rat model for evaluating 
potential lung carcinogenicity in humans (Document ID 2307, Attachment 
A, p. 30; 4209, p. 32). Specifically, the ACC highlighted studies by 
Holland (1995) and Saffiotti et al. (1996) indicating that bioassays in 
respirable crystalline silica-exposed mice, guinea pigs, and Syrian 
hamsters have not found increased lung cancer (Document ID 2307, 
Attachment A, p. 30, f. 51).
    The ACC proposed that the increased lung cancer risk in respirable 
crystalline silica-exposed rats is due to a particle overload 
phenomenon, in which lung clearance of nonfibrous durable particles 
initiates a non-specific response that results in intrapulmonary lung 
tumors (Document ID 2307, Attachment A, p. 30, n. 51). Dr. Cox, on 
behalf of the ACC, citing Mauderly (1997, included in Document ID 
3600), Oberdorster (1996, Document ID 3969), and Nikula et al. (1997, 
included in Document ID 3600), likewise commented that rats are 
``uniquely sensitive to particulate pollution, for species-specific 
reasons that do not generalize to other rodents or mammals, including 
humans'' (Document ID 2307, Attachment 4, p. 83). OSHA reviewed the 
three studies referenced by Dr. Cox and notes that two actually appear 
to support the use of the rat model and the third does not reject it. 
Mauderly (1997) noted that the rat model was the only one to correctly 
predict carcinogenicity after inhalation exposure to several types of 
asbestos, and highlighted the shortcomings of other models, such as 
those using hamsters, which are highly insensitive to particle-induced 
lung cancers (article included in Document ID 3600, pp. 1339-1343). 
While Mauderly (1997) advised caution when using the rat because it is 
the most sensitive rodent species for lung cancer, he concluded that 
``there is evidence supporting continued use of rats in exploration of 
carcinogenic hazards of inhaled particles,'' and that the other test 
species are problematic because they provide too many false negatives 
to be predictive (article included in Document ID 3600, p. 1343). 
Similarly, Oberdorster (1996), in discussing particle parameters used 
in the evaluation of exposure-dose-relationships of inhaled particles, 
stated that ``the rat model should not be dismissed prematurely'' 
(Document ID 3969, p. 73). Oberdorster (1996) postulated that humans 
and rats have very similar responses to particle-induced effects when 
analyzing the exposure-response relationship using particle surface 
area, rather than particle mass, as the exposure metric. Oberdorster 
concluded that there simply was not enough known regarding exact 
mechanisms to reject the model outright (Document ID 3969, pp. 85-87). 
The remaining paper cited by Dr. Cox, Nikula et al. (1997), evaluated 
the anatomical differences between primate and rodent responses to 
inhaled particulate matter and the role of clearance patterns and 
physiological responses to inhaled toxicants. The study noted that the 
differences between primate clearance patterns and rat clearance 
patterns may play a role in the pathogenesis from inhaled poorly 
soluble particles but did not dismiss the rat model as irrelevant to 
humans (Nikula, 1997, included in Document ID 3600, pp. 83, 93, 97).
    Thus, OSHA finds that the Mauderly (1997) and Oberdorster (1996) 
articles generally support the rat as an appropriate model for 
qualitatively assessing the hazards associated with particle 
inhalation. OSHA likewise notes that the rat model is a common and 
well-accepted toxicological model used to assess human health effects 
from toxicant inhalation (ILSI, 2000, Document ID 3906, pp. 2-9). OSHA 
evaluated the available studies in the record, both positive and non-
positive, and believes that it is appropriate to regard positive 
findings in experimental studies using rats as supportive evidence for 
the carcinogenicity of crystalline silica. This determination is 
consistent with that of IARC (Document ID 1473, p. 388) and NTP 
(Document ID 1164, p. 1), which also regarded the significant increases 
in incidence of malignant lung tumors in rats from multiple studies by 
both inhalation and intratracheal instillation of crystalline silica to 
be sufficient evidence of carcinogenicity in experimental animals and, 
therefore, to contribute to the evidence for carcinogenicity in humans.
3. Hypothesis That Lung Cancer Is Dependent on Silicosis
    The ACC asserted in its comments that ``if it exists at all, 
silica-related carcinogenicity most likely arises through a silicosis 
pathway or some other inflammation-mediated mechanism, rather than by 
means of a direct genotoxic effect'' (Document ID 2307, Attachment A, 
p. 52; 4209, p. 51; 2343, Attachment 1, pp. 40-44). It explained that 
the ``silicosis pathway'' means that lung cancer stems from chronic 
inflammatory lung damage, which in turn, ``implies that there is a 
threshold for any causal association between silica exposure and risk 
of lung cancer'' (Document ID 2307, Attachment A, pp. 52-53). The ACC 
went on to state that a mechanism that involves ROS, growth factors, 
and inflammatory cytokines from alveolar macrophages is ``most 
consistent'' with development of advanced chronic inflammation (e.g., 
epithelial hyperplasia, lung tissue damage, fibrosis, and silicosis). 
According to this hypothesis, silica-related lung cancer is restricted 
to people who have silicosis (Document ID 2307, Attachment 2, p. 7). 
Regarding this hypothesis, the ACC concluded, ``[t]his view of the 
likely mechanism for silica-related lung cancer is widely accepted in 
the scientific community, including by OSHA's primary source of silica-
related health risk estimates, Dr. Kyle Steenland. OSHA appears to 
share this view as well'' (Document ID 2307, Attachment A, p. 54).
    The ACC statement regarding acceptance by OSHA and the scientific 
community is inaccurate. It implies scientific consensus, as well as 
OSHA's concurrence, that the chronic inflammation from silicosis is the 
only mechanism by which crystalline silica exposure results in lung 
cancer. The ACC has over-simplified and neglected the findings of the 
mechanistic studies that show activation of phagocytic and epithelial 
cells to be an early cellular response to crystalline silica prior to 
chronic inflammation (see Document ID 1711, pp. 234-238). As discussed 
previously, alveolar macrophage activation leads to initial production 
of ROS and release of cytokine growth factors that could contribute to 
silica-induced carcinogenicity through both genotoxic and non-genotoxic 
mechanisms. The early cellular response does not require chronic 
inflammation and silicosis to be present, as postulated by the ACC. It 
is possible that the early mechanistic influences that increase cancer 
risk may be amplified by a later severe chronic inflammation or 
silicosis, if such a condition develops. However, as Brian Miller, 
Ph.D., stated ``this issue of silicosis being a precursor for lung 
cancer is unanswerable, given that we cannot investigate for early 
fibrotic lesions in the living, but must rely on radiographs.'' 
(Document ID 3574, Tr. 31).
    In pre-hearing comments the ACC commented, as proof of silicosis 
being linked to lung cancer, that fibrosis was linked to 
adenocarcinomas (Document ID 2307, Attachment A, p. 61). This statement 
is misleading. As explained

[[Page 16348]]

earlier, silicosis results from stimulation of fibroblast cells that 
cause lung fibrosis. Adenocarcinomas, a hallmark tumor type in 
respirable crystalline silica-induced lung cancer, are tumors that 
arise not from fibroblasts, but exclusively from lung epithelial cells 
(IARC, 2012, Document ID 1473, pp. 381-389, 392). These tumors may be 
linked to the genotoxic and non-genotoxic mechanisms that occur prior 
to fibrosis, not secondary to the fibrotic process itself.
    OSHA also received some comments that questioned the existence of a 
direct genotoxic mechanism. Jonathan Borak, M.D., on behalf of the U.S. 
Chamber of Commerce, commented, ``there is no direct evidence that 
silica causes cancer by means of a directly DNA-reactive mechanism'' 
(Document ID 2376, p. 21). Dr. Peter Morfeld, on behalf of the ACC, as 
well as Peter Valberg, Ph.D., and Christopher M. Long, Sc.D., of 
Gradient Corporation, on behalf of the U.S. Chamber of Commerce, cited 
a scientific article by Borm et al. (2011, included in Document ID 
3573) which reported finding evidence against a genotoxic mechanism and 
in favor of a mechanism secondary to chronic inflammation (Document ID 
3458, pp. 5-7; 4016, pp. 5-6; 4209, p. 51). Borm et al. (2011, included 
in Document ID 3573) analyzed 245 published studies from 1996 to 2008 
identified using the search terms ``quartz'' and `toxicity'' in 
conjunction with ``surface,'' ``inflammation,'' ``fibrosis,'' and 
``genotoxicity.'' The authors then estimated the lowest dose (in units 
of micrograms per cell surface area) to consistently induce DNA damage 
or induce markers of inflammation (e.g., IL-8 upregulation) in in vitro 
studies. They adjusted the in vitro doses for the lung surface area 
encountered in vivo and found the crystalline silica dose that produced 
primary genotoxicity was 60-120 times higher than the dose that 
produced inflammatory cytokines (Borm et al., 2011, included in 
Document ID 3573, p. 762). Drs. Valberg and Long concluded that Borm et 
al. demonstrated that genotoxicity was a secondary response to chronic 
inflammation, except at very high exposures at which genotoxicity 
independent of inflammation might occur. They also maintained that lung 
cancer as a secondary response to chronic inflammation is considered to 
have a threshold (Document ID 4016, p. 6).
    OSHA reviewed the Borm et al. study (2011, Document ID 3889), and 
notes several limitations. The authors examined the findings from 
various genotoxic assays (comet assay, 8-OH-dG, micronucleus test) 
(Borm et al., 2011, 3889, p. 758). They reported that 40 [mu]g/cm\2\ 
was the lowest dose in vitro to produce significant direct DNA damage 
from crystalline silica. This genotoxic dose appears to be principally 
obtained from a study of a specific quartz sample (i.e., DQ12) in a 
single human alveolar epithelial cell line (i.e., A549 cells), even 
though Appendix Table 3 cited in vitro studies using other cells (e.g., 
fibroblasts) and other types of quartz (e.g., MinUsil) that produced 
direct genotoxic effects at lower doses (Borm et al., 2011, Document ID 
3889, pp. 760, 769-770). This is especially pertinent since Borm et al. 
state that in vitro systems utilizing single-cell cultures are 
generally much less sensitive than in vivo systems, especially if 
attempting to determine oxidative stress-induced effects, since many 
cell culture systems use reagents that can scavenge ROS (Borm et al. 
2011, Document ID 3889, p. 760). There was no indication that the 
authors accounted for this deficiency. They go on to conclude that 
their work shows a large-scale variation in hazard across different 
forms of quartz with regard to effects such as DNA breakage (e.g., 
genotoxicity) and inflammation (Borm et al. 2011, Document ID 3889, p. 
762).
    The extreme variation in response along with reliance on an 
insensitive genotoxicity test system could overestimate the appropriate 
genotoxic dose in human lung cells in vivo. In addition, Borm et al. 
used the dose sufficient to initiate production of an inflammatory 
cytokine (i.e., IL-8) in the A549 cell-line as the threshold for 
inflammation. It is not clear that an early cellular response, such as 
IL-8 production necessarily reflects a sustained inflammatory response. 
In summary, OSHA finds inconsistencies in this analysis, leaving some 
questions regarding the study's conclusion that silica induces 
genotoxicity only as a secondary response to an inflammation-driven 
mechanism. While the in vitro dose comparisons in this study fail to 
demonstrate that genotoxicity is secondary to the inflammatory 
response, the study findings do indicate that cellular responses to 
crystalline silica that drive inflammation may also lead to 
tumorigenesis through both genotoxic and non-genotoxic mechanisms.
    Dr. Morfeld, in his hearing testimony on behalf of the ACC, 
referred to the paper by Borm et al. (2011) as reaching the conclusion 
that the mechanism of silica-related lung cancer is secondary 
inflammation-driven genotoxicity. As summarized by the ACC in post-
hearing comments, he observed that ``there are no crystalline silica 
particles found in the nucleus of the cells. There is nothing going on 
with particles in the epithelial cells inside the lung'' (Document ID 
4209, p. 52). In hearing testimony, however, Dr. Morfeld acknowledged 
that the Borm paper had limitations on extrapolating from in vitro to 
in vivo and cited a study by Donaldson et al. (2009), which discussed 
some of the limitations and the need for caution in extrapolating from 
in vitro to in vivo (Document ID 3582, Tr. 2076-2077; 3894, pp. 1-2). 
In considering this testimony, OSHA notes that the Donaldson et al. 
(2009) study, which includes the same authors as the Borm et al. (2011) 
study, acknowledged that direct interaction between respirable 
crystalline silica and epithelial cellular membranes induces 
intracellular oxidative stress which is capable of being genotoxic 
(Document ID 3894, p. 3). This is consistent with the OSHA position as 
well as the most recent IARC reevaluation of the cancer hazard from 
crystalline silica dust. As IARC stated in its most recent evaluation 
of the carcinogenicity of respirable crystalline silica under a section 
on direct genotoxicity and cell transformation (Document ID 1473, 
section 4.2.2, pp. 391-393):

    Reactive oxygen species are generated not only at the particle 
surface of crystalline silica, but also by phagocytic and epithelial 
cells exposed to quartz particles. . . . Oxidants generated by 
silica particles and by the respiratory burst of silica-activated 
phagocytic cells may cause cellular and lung injury, including DNA 
damage (Document ID 1473, p. 391).

    Given the IARC determination as well as the animal and in vitro 
studies reviewed herein, OSHA finds that there is no conclusive 
evidence that silica-related lung cancer only occurs as a secondary 
response to chronic inflammation, or that silicosis is a necessary 
prerequisite for lung cancer. Instead, OSHA finds support in the 
scientific literature for a conclusion that tumors may form through 
genotoxic as well as non-genotoxic mechanisms that result from 
respirable crystalline silica interaction with alveolar macrophages and 
other lung cells prior to onset of silicosis.
4. Hypothesis That Crystalline Silica-Induced Lung Disease Exhibits a 
Threshold
    It is well established that silicosis arises from an advanced 
chronic inflammation of the lung. As noted above, a common hypothesis 
is that pathological conditions that depend on chronic inflammation may 
have a threshold. The exposure level at which silica-induced health 
effects might begin

[[Page 16349]]

to appear, however, is poorly characterized in the literature (see 
Section V.I, Comments and Responses Concerning Thresholds for Silica-
Related Diseases). The threshold exposure level required for a 
sustained inflammatory response is dependent upon multiple pro- and 
anti-inflammatory factors that can be quite variable from individual to 
individual and from species to species (Document ID 3896).
    Discounting or overlooking the evidence that respirable crystalline 
silica may be genotoxic in the absence of chronic inflammation, Drs. 
Valberg and Long commented that crystalline silica follows a threshold 
paradigm for poorly soluble particles (PSPs). PSPs are defined 
generally as nonfibrous particles of low acute toxicity, which are not 
directly genotoxic (ILSI, 2000, Document ID 3906, p. 1). Specifically, 
Drs. Valberg and Long stated:

    Mechanisms whereby lung cells respond to retention of a wide 
variety of PSPs, including crystalline silica, follow a generally 
accepted threshold paradigm, where the initiation of a chronic 
inflammatory response is a necessary step in the disease process, 
and the inflammatory response does not become persistent until 
particle retention loads become sufficient to overwhelm lung defense 
mechanisms. This overall progression from increased but controlled 
pulmonary inflammation across a threshold exposure that leads to 
lung damage has been described by a number of investigators 
(Mauderly and McCunney, 1995; ILSI, 2000; Boobis et al., 2009; 
Porter et al. 2004) (Document ID 2330, p. 19).

    Similarly, Dr. Cox, in his post-hearing comments, discussed his 
2011 article describing a quantifiable exposure-response threshold for 
lung diseases induced by inhalation of respirable crystalline silica 
(Document ID 4027, p. 29). Dr. Cox hypothesized the existence of an 
exposure threshold such that exposures to PSPs, which he described as 
including titanium dioxide, carbon black, and crystalline silica, must 
be intense enough and last long enough to disrupt normal homeostasis 
(i.e., normal cellular functions) and overwhelm normal repair 
processes. Under the scenario he described, a persistent state of 
chronic, unresolved inflammation results in a disruption of macrophage 
and neutrophil ability to clear silica and other foreign particles from 
the lung (Document ID 1470, pp. 1548-1551, 1555-1556).
    OSHA disagrees with these characterizations about exposure 
thresholds because, among other reasons, respirable crystalline silica 
is not generally considered to be in the class of substances defined as 
PSPs.\7\ Specifically, regarding the comments of Drs. Valberg and Long, 
OSHA notes that the two cited documents (Mauderly and McCunney, 1995, 
and ILSI, 2000) summarizing workshops on PSPs did not include 
crystalline silica in the definition of PSP and the lung ``overload'' 
concept, instead highlighting silica's cytotoxic and genotoxic 
mechanisms. Mauderly and McCunney (1995) stated, ``[i]t is generally 
accepted that the term `overload' should be used in reference to 
particles having low cytotoxicity, which overload clearance 
[mechanisms] by virtue of the mass, volume, or surface area of the 
deposited material (Morrow, 1992)'' (p. 3, article cited in Document ID 
2330, p. 19). Mauderly specifically cited quartz as a cytotoxic 
particle that may fall outside this definition (p. 24, article cited in 
Document ID 2330, p. 19). The International Life Science Institute's 
(ILSI) Workshop Report (2000) intended only to address particles of 
``low acute toxicity,'' such as carbon black, coal dust, soot, and 
titanium dioxide (Document ID 3906, p. 1). OSHA believes that the 
cytotoxic nature of crystalline silica would exclude it from the class 
of rather nonreactive, non-toxic particles mentioned above. Therefore, 
the Agency concludes that most scientific experts would not include 
crystalline silica in the class of substances known as PSPs, nor intend 
for findings regarding PSPs to be extrapolated to crystalline silica.
---------------------------------------------------------------------------

    \7\ OSHA notes that crystalline silica has many mechanistic 
features in common with asbestos. They are both durable, 
biopersistent mineral forms where there is sufficient evidence of an 
association with lung cancer (i.e., IARC Group 1 carcinogens), 
chronic lung inflammation, and severe pulmonary fibrosis (i.e., 
silicosis and asbestosis) in humans. Like crystalline silica, 
asbestos has reactive surfaces or other physiochemical properties 
able to hinder phagocytosis and activate macrophages to release 
reactive oxygen species, cytokines, and growth factors that lead to 
DNA damage, cytotoxicity, cell proliferation and an inflammatory 
response responsible for the disease outcomes mentioned above (see 
IARC 2012, Document ID 1473, pp. 283-290). Crystalline silica and 
asbestos can trigger phagocytic activation well below the high mass 
burdens required to ``overload'' the lung and impair pulmonary 
clearance that is typical of carbon black and other low acute-
toxicity PSPs.
---------------------------------------------------------------------------

    During the public hearing, OSHA questioned Dr. Morfeld about the 
relevance of the rat overload response and whether he considered 
crystalline silica to be like other PSPs such as carbon black. Dr. 
Morfeld replied that he was well aware of the literature and indicated 
that crystalline silica was not considered one of the PSPs 
(specifically not like carbon black) that these reports reviewed 
(Document ID 3582, Tr. 2072-2074). OSHA also notes a report of the 
European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC), 
which was cited by the ACC (Document ID 4209, p. 32) and stated that 
``particles exhibiting significant surface related (cyto)toxicity like 
crystalline silica (quartz) and/or other specific toxic properties do 
not fall under this definition [of PSPs]'' (Document ID 3897, p. 5).
    Respirable crystalline silica differs from PSPs because it does not 
require particle overload to induce the same response typical of PSPs. 
``Overload'' refers to the consequence of exposure that results in a 
retained lung burden of particles that is greater than the steady-state 
burden predicted from deposition rates and clearance kinetics (Document 
ID 4174, p. 20). This is a result of a volumetric over-exposure of dust 
in the lung, which overwhelms macrophage function. Respirable 
crystalline silica does not operate on this mechanism since macrophage 
function is inhibited by the cytotoxic nature of respirable crystalline 
silica rather than a volumetric overload (Oberdorster, 1996, Document 
ID 3969). Therefore, respirable crystalline silica does not require 
particle overload to induce the same response. Studies have found that 
the respirable crystalline silica exposure levels required to induce 
tumor formation in some animal studies are similar to those observed in 
human studies, whereas studies involving PSPs tend to show responses at 
much higher levels of exposure (Muhle et al., 1991, Document ID 1284; 
Muhle et al., 1995, 0378; Saffiotti and Ahmed, 1995, 1121).
    A study by Porter et al. (2004) demonstrated that pulmonary 
fibrosis induction does not require silica particle overload (Document 
ID 0410, p. 377). The ACC cited this study in its post-hearing brief, 
stating, ``Porter . . . noted that the response of the rat lung to 
inhaled crystalline silica particles is biphasic, with a below-
threshold phase characterized by increased but controlled pulmonary 
inflammation'' (Document ID 4209, p. 52). OSHA notes that this biphasic 
response is due in part to the cytotoxic nature of crystalline silica, 
which disrupts macrophage clearance of silica particles leading to a 
chronic inflammatory response at less than overload conditions. While 
there are some mechanistic similarities, OSHA believes that the 
argument that crystalline silica operates on the basis of lung overload 
is erroneous and based on false assumptions that ignore toxicological 
properties unique to crystalline silica, such as cytotoxicity and the 
generation of intracellular ROS (Porter et al., 2002, Document ID 1114; 
Porter et al., 2004, 0410). As previously discussed, the generation of 
ROS could

[[Page 16350]]

potentially damage cellular DNA by a genotoxic mechanism that may not 
exhibit a threshold.
    OSHA thoroughly reviewed Dr. Cox's 2011 article (Document ID 1470), 
in which he proposed a threshold for crystalline silica, in its 
Supplemental Literature Review (Document ID 1711, Attachment 1, pp. 37-
39). OSHA concluded that the evidence used to support Cox's assertion 
that the OSHA PEL was below a threshold for lung disease in humans was 
not supported by the evidence presented (Document ID 1470, p. 1543; 
1711, Attachment 1). Specifically, Cox (2011) modelled a threshold 
level for respirable crystalline silica using animal studies of PSPs. 
This approach, according to the ILSI report (2000) and ECETOC report 
(2013), is clearly not appropriate since the cytotoxic nature of 
crystalline silica is not consistent with the low-toxicity PSPs 
(Document ID 3906, p. 1; 3897, p. 5). Dr. Cox (2011) categorized 
crystalline silica incorrectly as a PSP and ignored the evidence for 
cytotoxicity and genotoxicity associated with crystalline silica. He 
further failed to consider or include studies indicating a tumor 
response at exposure levels below that leading to an excessive chronic 
inflammatory response, such as Porter et al. (2002) and Muhle et al. 
(1995) (Document ID 1114; 0378). Thus, OSHA considers the threshold 
model designed by Dr. Cox (2011, Document ID 1470) and referenced by 
Drs. Valberg and Long (Document ID 2330) to be contradicted by the best 
available evidence regarding the toxicological properties of respirable 
crystalline silica. Although OSHA acknowledges the possible existence 
of a threshold for an inflammatory response, the Agency believes that 
the threshold is likely much lower than that advocated by industry 
representatives such as the ACC and the Chamber of Commerce (see 
Section V.I, Comments and Responses Concerning Thresholds for Silica-
Related Diseases).
    OSHA concludes that a better estimate of a threshold effect for 
inflammation and carcinogenesis was done by Kuempel et al. (2001, 
Document ID 1082). These researchers studied the minimum human 
exposures necessary to achieve adverse functional and pathological 
evidence of inflammation. They employed a physiologically-based lung 
dosimetry model, included more relevant studies, and considered a 
genotoxic effect for lung cancer (Kuempel et al., 2001, Document ID 
1082; see 1711, pp. 231-232). Briefly, Kuempel et al. evaluated both 
linear and nonlinear (threshold) models and determined that the average 
minimum critical quartz lung burden (Mcrit) in rats 
associated with reduced pulmonary clearance and increased neutrophil 
inflammation was 0.39 mg quartz/g lung tissue. Mcrit is 
based on the lowest observed adverse effect level in a study in rats 
(Kuempel, 2001, Document ID 1082, pp. 17-23). A human lung dosimetry 
model, developed from respirable coal mine dust and quartz exposure and 
lung burden data in UK coal miners (Tran and Buchanan, 2001, Document 
ID 1126), was then used to estimate the human-equivalent working 
lifetime exposure concentrations associated with lung doses. An 8-hour 
time-weighted average (TWA) concentration of 0.036 mg/m\3\ (36 [mu]g/
m\3\) over a 45-year working lifetime was estimated to result in a 
human-equivalent lung burden to the average Mcrit in rats 
(Document ID 1082, pp. 24-26). OSHA peer reviewer Gary Ginsburg, Ph.D., 
summarized, ``the Kuempel et al. (2001, 2001b) rat analysis of lung 
threshold loading and extrapolation to human dosimetry leads to the 
conclusion that in the median case this threshold is approximately 3 
times below the current [now former] OSHA PEL'' (Document ID 3574, pp. 
23). This estimated threshold would be significantly below the final 
PEL of 50 [mu]g/m\3\.
    In pre-hearing comments, ACC stated that some health organizations 
suggested a silicosis-dependent threshold exists for lung cancer (ACC, 
Document ID 2307, Attachment A, pp. 60-62). Specifically, ACC cited 
Environment and Health Canada as stating:

    Although the mechanism of induction for the lung tumours has not 
been fully elucidated, there is sufficient supportive mode of action 
evidence from the data presented to demonstrate that a threshold 
approach to risk assessment is appropriate based on an understanding 
of the key events in the pathogenesis of crystalline silica induced 
lung tumours (pp. 49-51 as cited by ACC, Document ID 2307, p. 62).

    In addition to the statement submitted by ACC, Environment and 
Health Canada also stated that:

    While there is sufficient evidence to support key events in a 
threshold mode of action approach for lung tumours, the molecular 
mechanism is still not fully elucidated. Also, despite the fact that 
the effects seen in rats parallel the effects observed in human 
studies, additional mechanistic studies could further clarify why 
lung tumours are not seen in all experimental animals . . . Thus, 
the question of whether silica exposure, in the absence of silicotic 
response, results in lung tumours remains unanswered.'' (pp. 51-52 
as cited by ACC, Document ID 2307, pp. 59-61).

    It should be noted that the Environment and Health Canada report 
was to determine general population risk of exposure to respirable 
crystalline silica as a fraction of PM10. Environment and 
Health Canada found that levels 0.1-2.1 [mu]g/m\3\ respirable 
crystalline silica were sufficiently protective for the general 
population because they represented a margin of exposure (MOE) 23-500 
times lower than the 50 [mu]g/m\3\ quartz concentration associated with 
silicosis in humans (pp. 50-51 as cited by ACC, Document ID 2307, pp. 
59-61).
    A report by Mossman and Glenn (2013) reviewed the findings from 
several international OEL setting panels (Document ID 4070). The report 
cites findings from the European Commission's Scientific Committee on 
Occupational Exposure Limits for respirable crystalline silica. The 
findings ``acknowledged a No Observed Adverse Exposure Level (NOAEL) 
for respirable crystalline silica in the range below 0.020 mg/m\3\, but 
stated that a clear threshold for silicosis could not be identified'' 
(Mossman and Glen, 2013; Document ID 4070, p. 655). The report went on 
to state that SCOEL (2002) recommended that an OEL should lie below 50 
[mu]g/m\3\ (Document ID 4070, p. 655). Therefore, even if silica-
induced lung cancer were limited only to a mechanism that involved an 
inflammation-dependent threshold, OSHA concludes that exposure 
threshold would likely be lower than the final PEL.
5. Renal Disease and Autoimmunity
    While mechanistic data is limited, other observed health effects 
from inhalation of respirable crystalline silica include kidney and 
autoimmune effects. Translocation of particles through the lymphatic 
system and filtration through the kidneys may induce effects in the 
immune and renal systems similar to the types of changes observed in 
the lung (Miller, 2000, Document ID 4174, pp. 40-45). A review of the 
available literature indicates that respirable crystalline silica most 
likely induces an oxidative stress response in the renal and immune 
cells similar to that described above (Donaldson et al., 2009, Document 
ID 3894).
6. Conclusion
    OSHA has reviewed and responded to the comments received on the 
mechanistic studies of respirable crystalline silica-induced lung 
cancer and silicosis, as well as comments that the mechanistic data 
imply the existence of an exposure threshold. OSHA concludes that: (1) 
Lung cancer likely results from both genotoxic and non-genotoxic 
mechanisms that arise during early cellular responses as well

[[Page 16351]]

as during chronic inflammation from exposure to crystalline silica; (2) 
there is not convincing data to demonstrate that silicosis is a 
prerequisite for lung cancer; (3) experimental studies in rats are 
relevant to humans and provide supporting evidence for carcinogenicity; 
(4) crystalline silica does not behave like PSPs such as titanium 
dioxide; and (5) any threshold for an inflammatory response to 
respirable crystalline silica is likely several times below the final 
PEL of 50 [mu]g/m\3\. Thus, the best available evidence on this issue 
supports OSHA's findings that respirable crystalline silica increases 
the risk of lung cancer in humans, even in the absence of silicosis, 
and that lung cancer risk can be increased by exposure to crystalline 
silica at or below the new OSHA PEL of 50 [mu]g/m\3\.

I. Comments and Responses Concerning Thresholds for Silica-Related 
Diseases

    In this section, OSHA discusses comments focused on the issue of 
exposure-response thresholds for silica exposure. In the comments 
received by OSHA on this topic, an exposure-response ``threshold'' for 
silica exposure typically refers to a level of exposure such that no 
individual whose exposure is below that level would be expected to 
develop an adverse health effect. Commenters referred to thresholds 
both in terms of concentration and cumulative exposure (i.e., a level 
of cumulative exposure below which an individual would not be expected 
to develop adverse health effects). In addition to individual 
thresholds, some commenters referred to a ``population average 
threshold,'' that is, the mean or median value of individual thresholds 
across a population of workers. There is significant scientific 
controversy over whether any such thresholds exist for silicosis and 
lung cancer, as well as the cumulative exposure level or concentration 
at which a threshold effect may occur and whether certain statistical 
modeling approaches can be used to identify threshold effects.
    OSHA has reviewed the evidence in the record pertaining to 
thresholds, and has determined that the best available evidence 
supports the Agency's use of non-threshold exposure-response models in 
its risk assessments for silicosis and lung cancer. The voluminous 
scientific record accrued by OSHA in this rulemaking supports lowering 
the existing PEL to 50 [mu]g/m\3\. Rather than indicating a threshold 
of risk that starts above the previous general industry PEL, the weight 
of this evidence, including OSHA's own risk assessment models, supports 
a conclusion that there continues to be significant, albeit reduced, 
risk at the 50 [mu]g/m\3\ exposure limit. OSHA's evaluation of the best 
available evidence on thresholds indicates that there is considerable 
uncertainty about whether there is any threshold below which silica 
exposure causes no adverse health effects; but, in any event, the 
weight of evidence supports the view that, if there is a threshold of 
exposure for the health effects caused by respirable crystalline 
silica, it is likely lower than the new PEL of 50 [mu]g/m\3\. 
Commenters have not provided convincing evidence of a population 
threshold (e.g., an exposure level safe for all workers) above the 
revised PEL. In addition, OSHA's final risk assessment demonstrates 
that achieving this limit--which OSHA separately concludes is overall 
the lowest feasible level for silica-generating operations--will result 
in significant reductions in mortality and morbidity from occupational 
exposure to respirable crystalline silica.
1. Thresholds--General
    In the Preliminary Quantitative Risk Assessment (QRA) (Document ID 
1711, pp. 275, 282-285), OSHA reviewed evidence on thresholds from a 
lung dosimetry model developed by Kuempel et al. (2001, Document ID 
1082) and from epidemiological analyses conducted by Steenland and 
Deddens (2002, Document ID 1124). As discussed in the Preliminary QRA, 
Kuempel et al. (2001) used kinetic lung models for both rats and humans 
to relate lung burden of crystalline silica and estimate a minimum 
critical lung burden (Mcrit) of quartz above which particle 
clearance begins to decline and lung inflammation begins to increase 
(early steps in the process of developing silica-related disease). The 
Mcrit would be achieved by a human equivalent airborne 
exposure to 36 [mu]g/m\3\ for 45 years, based on the authors' rat-to-
human lung model conversion. Exposures below this level would not lead 
to an excess lung cancer risk in the average individual, if it were 
assumed that cancer is strictly a secondary response to persistent 
inflammation. OSHA notes, however, that if some of the silica-related 
lung cancer risk occurs as a result of direct genotoxicity from early 
cellular interaction with respirable silica particles, then this 
threshold value may not be applicable. Since silicosis is caused by 
persistent lung inflammation, this exposure level could be viewed as a 
possible average threshold level for that disease as well (Document ID 
1711, p. 284). As 36 [mu]g/m\3\ is well below the previous general 
industry PEL of 100 [mu]g/m\3\ and below the final PEL of 50 [mu]g/
m\3\, the Kuempel et al. study showed no evidence of an exposure-
response threshold high enough to impact OSHA's choice of PEL.
    Steenland and Deddens (2002, Document ID 1124) examined a pooled 
lung cancer study originally conducted by Steenland et al. (2001a). 
They found that a threshold model based on the log of cumulative dose 
(15-year lag) fit better than a no-threshold model, with the best 
threshold at 4.8 log mg/m\3\-days (representing an average exposure of 
10 [mu]g/m\3\ over a 45-year working lifetime). OSHA preliminarily 
concluded that, in the Kuempel et al. (2001) study and among the 
studies evaluated by Steenland et al. (2001a) in the pooled analysis, 
there was no empirical evidence of a threshold for lung cancer in the 
exposure range represented by the previous and final PELs (i.e., at 50 
[mu]g/m\3\ or higher) (Document ID 1711, pp. 275, 284). Thus, based on 
these two studies, workers exposed at or below the new PEL of 50 [mu]g/
m\3\ over a working lifetime still face a risk of developing silicosis 
and lung cancer because their exposure would be above the supposed 
exposure threshold.
    In its prehearing comments, the ACC argued that OSHA's examination 
of the epidemiological evidence, along with animal studies and 
mechanistic considerations, ``has not shown that reducing exposures 
below currently permitted exposure levels would create any additional 
health benefits for workers. OSHA's analysis and the studies on which 
it relies have not demonstrated the absence of an exposure threshold 
above 100 [mu]g/m\3\ for the various adverse health effects considered 
in the QRA'' (Document ID 2307, Attachment A, p. 26; also 2348, 
Attachment 1, p. 33). According to the ACC, an exposure threshold above 
OSHA's previous general industry PEL of 100 [mu]g/m\3\ means that 
workers exposed below that level will not get sick, negating the need 
to lower the PEL (Document ID 2307, Attachment A, p. 91).
    Members of OSHA's peer review panel for the Review of Health 
Effects Literature and Preliminary Quantitative Risk Assessment 
(Document ID 1711) rejected the ACC's comments as unsupportable. Peer 
reviewer Mr. Bruce Allen stated: ``it is essentially impossible to 
distinguish between dose-response patterns that represent a threshold 
and those that do not'' in epidemiological data (Document ID 3574, p. 
8). Peer reviewer Dr. Kenneth Crump similarly commented:

    OSHA is on very solid ground in the [Preliminary QRA's] 
statement that ``available information cannot firmly establish a 
threshold exposure for silica-

[[Page 16352]]

related effects'' . . . the hypothesis that a particular dose 
response does not have a threshold is not falsifiable. Similarly, 
the hypothesis that a particular dose response does have a threshold 
is not falsifiable (Document ID 3574, p. 17).

    Dr. Cox, representing the ACC, agreed with Dr. Crump that ``it's 
impossible to prove a negative, empirically . . . you could never rule 
out that possibility'' of a threshold at a low level of exposure 
(Document ID 3576, Tr. 402). However, he contended that it is possible 
to rule out a threshold in the higher-level range of observed exposures 
based on observed illness: ``I think that there are plenty of chemicals 
for which the hypothesis of a threshold exist[ing] at or above current 
standards could be ruled out because you see people getting sick at 
current levels'' (Document ID 3576, Tr. 403). Other commenters stated 
their belief that workers recently diagnosed with silicosis must have 
had exposures above the previous general industry PEL and, based on 
this supposition, concluded that OSHA has not definitively proven risk 
to workers exposed below the previous general industry PEL (Document ID 
4224, pp. 2-5; Tr. 3582, pp. 1951-1963).
    OSHA agrees with Dr. Cox that observation of workers ``getting sick 
at current levels'' can rule out a threshold effect at those levels. As 
is discussed below, there is evidence that workers exposed to silica at 
cumulative or average exposure levels permitted under the previous PELs 
have become ill and died as a result of their exposure. OSHA thus 
strongly disagrees with any implication from commenters that the Agency 
should postpone reducing a PEL until it has extensive documentation of 
sick and dying workers to demonstrate that the current PEL is not 
sufficiently protective (see Section II, Pertinent Legal Authority, and 
Section VI, Final Quantitative Risk Assessment and Significance of 
Risk).
    The ACC's and Chamber's comments on this issue essentially argue 
that the model OSHA used to assess risk was inadequate to assess 
whether a threshold of risk exists and, if one does exist, at what 
level (Document ID 2307, Attachment A, pp. 52-65; 2376, pp. 20-22; 
2330, pp. 17-21). According to OSHA peer reviewer Dr. Crump, however, 
the analytical approach taken by OSHA in the Preliminary QRA was 
appropriate. Considering the inherent limitations of epidemiological 
data:

an attempt to distinguish between threshold and non-threshold dose 
responses is not even a scientific exercise . . . The best that can 
be done is to attempt to place bounds on the amount of risk at 
particular exposures consistent with the available data, which is 
what OSHA had done in their risk assessment (Document ID 3574, p. 
17).

    A further source of uncertainty in investigating thresholds was 
highlighted by Dr. Mirer, on behalf of the AFL-CIO (Document ID 3578, 
Tr. 988-989) and by peer reviewer Dr. Andrew Salmon, who stated:

[m]any of the so-called thresholds seen in epidemiological studies 
represent thresholds of observability rather than thresholds of 
disease incidence . . . studies (and anecdotal observations) with 
less statistical power and shorter post-exposure followup (or none) 
will necessarily fail to see the less frequent and later-appearing 
responses at lower doses. This creates an apparent threshold which 
is higher in these studies than the apparent threshold implied by 
studies with greater statistical power and longer follow-up 
(Document ID 3574, p. 37).

    Peer reviewer Dr. Gary Ginsberg suggested that, recognizing these 
inherent limitations, OSHA should characterize the body of evidence and 
argument surrounding thresholds by discussing the following factors 
related to whether a threshold for silica-related health effects exists 
at exposure levels above the previous general industry PEL:

the choices relative to the threshold concept for the silica dose 
response . . . [including] specific dose response datasets that are 
consistent with a linear or a threshold-type model, if a threshold 
seems likely, where was it seen relative to the current and proposed 
PEL, and a general discussion of mechanism of action, measurement 
error and population variability as concepts that can help us 
understand silica dose response for cancer and non-cancer endpoints 
(Document ID 3574, p. 24).

    Following Dr. Ginsberg's suggestion, OSHA has, in its final health 
and risk analysis, considered the epidemiological evidence relevant to 
possible threshold effects for silicosis and lung cancer. As discussed 
below, first in ``Thresholds--Silicosis and NMRD'' and then in 
``Thresholds--Lung Cancer,'' OSHA has carefully considered comments 
about statistical methods, exposure measurement uncertainty, and 
variability as they pertain to threshold effects. The discussion 
addresses the epidemiological evidence with respect to both cumulative 
and concentration thresholds. For reference, a working lifetime (45 
years) of exposure to silica at the previous general industry PEL (100 
[mu]g/m\3\) and the final PEL (50 [mu]g/m\3\) yield cumulative 
exposures of 4.5 mg/m\3\-yrs and 2.25 mg/m\3\-yrs, respectively. Other 
sections with detailed discussions pertinent to threshold issues 
include Section V.H, Mechanisms of Silica-Induced Adverse Health 
Effects, and Section V.K, Comments and Responses Concerning Exposure 
Estimation Error and ToxaChemica's Uncertainty Analysis.
2. Thresholds--Silicosis and NMRD
    OSHA has determined that the studies most relevant to the threshold 
issue in this rulemaking are those of workers who have cumulative 
exposures or average exposure concentrations below the levels 
associated with the previous general industry PEL (100 [mu]g/m\3\, or 
cumulative exposure of 4.5 mg/m\3\-yrs). Contrary to comments that OSHA 
only relied on studies involving exposures far above the levels of 
interest to OSHA in this rulemaking, and then extrapolated exposure-
response relationships down to relevant levels (e.g., Document ID 2307, 
Attachment A, pp. 94-95; 4226, p. 2), a number of silicosis studies 
included workers who were exposed at levels close to or below the 
previous OSHA PEL for general industry. For example, four of the six 
cohorts of workers in the pooled silicosis mortality risk analysis 
conducted by Mannetje et al. (2002) had median cumulative exposures 
below 2.25 mg/m\3\-yrs., and three had median silica concentrations 
below 100 [mu]g/m\3\ (Mannetje et al., 2002, Document ID 1089, p. 724). 
Other silicosis studies with significant numbers of relatively low-
exposed workers include analyses of German pottery workers (Birk et 
al., 2009, Document ID 4002, Attachment 2; Mundt et al., 2011, 1478; 
Morfeld et al., 2013, 3843), Vermont granite workers (Attfield and 
Costello, 2004, Document ID 0285; Vacek et al., 2011, 1486), and 
industrial sand workers (McDonald et al., 2001, Document ID 1091; 
Hughes et al., 2001, 1060; McDonald et al., 2005, 1092). In this 
section, OSHA will discuss each of them in relationship to whether they 
suggest the existence of a threshold above 100 [mu]g/m\3\, the previous 
PEL for general industry.
a. Mannetje et al. Pooled Study and Related Analyses
    Mannetje et al. (2002b, Document ID 1089) estimated excess lifetime 
risk of silicosis based on six of the ten cohorts that were part of the 
IARC multi-center exposure-response study (Steenland et al., 2001a, 
Document ID 0452). The six cohorts were U.S. diatomaceous earth (DE) 
workers, Finnish granite workers, U.S. granite workers, U.S. industrial 
sand workers, U.S. gold miners, and Australian gold miners. Together, 
the cohorts included 18,634 subjects and 170 silicosis deaths. All 
cohorts except the Finnish granite workers and Australian gold miners 
had significant numbers of workers with median

[[Page 16353]]

cumulative and/or average exposures below the levels associated with 
OSHA's previous general industry PEL. Checking for nonlinearities in 
their exposure-response model, Mannetje et al. found that a five-knot 
cubic spline model (which allows for deviations, such as thresholds, 
from a linear relationship) did not fit the data better than the linear 
model used in their main analysis. The result of this attempt to check 
for nonlinearities suggests that there is no threshold effect in the 
relationship between cumulative silica exposure and silicosis risk in 
the study. Significantly, NIOSH stated that the results of Mannetje et 
al.'s analysis ``suggest the absence of threshold at the lowest 
[cumulative] exposure analyzed . . . in fact, the trend for silicosis 
mortality risk extends down almost linearly to the lowest cumulative 
exposure stratum'', in which ``the average cumulative exposure is the 
equivalent of 45 years of exposure at 11.1 [mu]g/m\3\ silica'' 
(Document ID 4233, pp. 34-35). This level is significantly below the 
new OSHA PEL of 50 [mu]g/m\3\.
    As discussed in Section V.K, Comments and Responses Concerning 
Exposure Estimation Error and ToxaChemica's Uncertainty Analysis, OSHA 
commissioned Drs. Kyle Steenland and Scott Bartell to examine the 
potential effects of exposure measurement error on the mortality risk 
estimates derived from the pooled studies of lung cancer (Steenland et 
al., 2001, Document ID 0452) and silicosis (Mannetje et al., 2002b, 
Document ID 1089). Their analysis of the pooled data, using a variety 
of standard statistical techniques (e.g., regression analysis), also 
found the data either consistent with the absence of a threshold or 
inconsistent with the existence of a threshold \8\ (Document ID 0469). 
Thus, neither Mannetje et al. nor Steenland and Bartell's analyses of 
the pooled cohorts suggested the existence of a cumulative exposure 
threshold effect; in fact, they suggested the absence of a threshold. 
Given the predominance in these studies of cohorts where at least half 
of the workers had cumulative exposures below 4.5 mg/m\3\-yrs, OSHA 
believes these results constitute strong evidence against an exposure 
threshold above the level of cumulative exposure resulting from long-
term exposure at the previous PEL of 100 [mu]g/m\3\.
---------------------------------------------------------------------------

    \8\ This analysis included a log-cumulative logistic regression 
model, as well as a categorical analysis and five-knot restricted 
cubic spline analysis using log-cumulative exposure. Had the spline 
analysis shown a better-fitting model with a flat exposure-response 
at low cumulative exposure levels, it might have suggested a 
threshold effect for cumulative exposure. However, no significant 
difference was observed between the parametric model and the two 
other models, which had greater flexibility in the shape of the 
exposure-response (Document ID 0469, p. 50, Figure 5).
---------------------------------------------------------------------------

b. Vermont Granite Workers
    As discussed in the Supplemental Literature Review of 
Epidemiological Studies, Vacek et al. (2011, Document ID 1486) examined 
exposures from 1950 to 1999 for a group of 7,052 workers in the Vermont 
granite industry (Document ID 1711, Attachment 1, pp. 2-5). The 
exposure samples show relatively low exposures for the worker 
population. For the period 1950 to 2004, Verma et al. (2012), who 
developed the job exposure matrix used by Vacek et al., estimated that 
average exposure concentrations in 21 of 22 jobs were below 100 [mu]g/
m\3\, and 11 of the 22 job classes were at 50 [mu]g/m\3\ or below. The 
remaining job category, laborer, had an estimated average exposure 
concentration of exactly 100 [mu]g/m\3\ (Verma et al., 2011, Document 
ID 1487, p. 75).
    Six of the 5,338 cohort members hired in or after 1940, when 
Vermont's dust control program was in effect, were identified as having 
died of silicosis by the end of the follow-up period (Vacek et al., 
Document ID 1486, p. 314). The frequency of observed silicosis 
mortality in the population is significant by OSHA standards (1.1 per 
1,000 workers), and may be underestimated due to under-reporting of 
silicosis as a cause of death (see Section V.E, Comments and Responses 
Concerning Surveillance Data on Silicosis Morbidity and Mortality). 
This observed silicosis mortality shows that deaths from silicosis 
occurred among workers hired after silica concentrations were reduced 
below OSHA's previous general industry PEL. It therefore demonstrates 
that a threshold for silicosis above 100 [mu]g/m\3\ is unlikely.
    In terms of morbidity, Graham et al.'s study of radiographic 
evidence of silicosis among retired Vermont granite workers found 
silicosis in 5.7 percent of workers hired after 1940 (equivalent to 57/
1,000 workers) (Graham et al., 2004, Document ID 1031, p. 465). OSHA 
concludes that these studies of low-exposed workers in the Vermont 
granite industry show significant risk of silicosis--both mortality and 
morbidity--at concentrations below the previous PELs. These studies 
also indicate that a threshold at an exposure concentration 
significantly above the previous PEL for general industry, as posited 
by industry representatives, is unlikely.
c. U.S. Industrial Sand Workers
    In an exposure-response study of 4,027 workers in 18 U.S. 
industrial sand plants, Steenland and Sanderson (2001) reported that 
approximately three-quarters of the workers with complete work 
histories had cumulative exposures below 1.28 mg/m\3\-yrs, well below 
the cumulative exposure of 2.25 mg/m\3\-yrs associated with a working 
lifetime of exposure at the final PEL of 50 [mu]g/m\3\ (Document ID 
0455, p. 700). The study identified fourteen deaths from silicosis and 
unspecified pneumoconiosis (~3.5 per 1,000 workers) (Document ID 0455, 
p. 700), of which seven occurred among workers with cumulative 
exposures below 1.28 mg/m\3\-yrs. As with other reports of silicosis 
mortality, this figure may underestimate the true rate of silicosis 
mortality in this worker population.
    Hughes et al. (2001) reported 32 cases of silicosis mortality in a 
cohort of 2,670 workers at nine North American industrial sand plants 
(~12 per 1,000) (Document ID 1060, p. 203). The authors developed a 
job-exposure matrix based on exposure samples collected by the 
companies and by MSHA between 1973 and 1994, along with the 1946 
exposure survey used by Steenland and Sanderson (2001, Document ID 
0455; 2307, Attachment 7, p. 6). Job histories were available for 29 
workers who died of silicosis. Of these, fourteen had estimated 
cumulative exposure less than or equal to 5 mg/m\3\-yrs, and seven had 
cumulative exposures less than or equal to 1.5 mg/m\3\-yrs (Document ID 
1060, p. 204). Both studies clearly showed silicosis risk among workers 
whose cumulative exposures were comparable to those that workers could 
experience under the final PEL (Document ID 0455, p. 700; 1060, p. 
204), indicating that a threshold above this level of cumulative 
exposure is unlikely.
d. German Porcelain Workers
    A series of papers by Birk et al. (2009, Document ID 4002, 
Attachment 2; 2010, Document ID 1467), Mundt et al. (2011, Document ID 
1478), and Morfeld et al. (2013, Document ID 3843) examined silicosis 
mortality and morbidity in a population of over 17,000 workers in the 
German porcelain industry. Cohort members' annual average 
concentrations of respirable quartz dust were reconstructed from 
detailed work histories and dust measurements collected in the industry 
from 1951 onward (Birk et al., 2009, Document ID 4002, Attachment 2, 
pp. 374-375). Morfeld et al. observed 40 silicosis morbidity cases (ILO 
profusion category 1/1 or greater), and noted that additional

[[Page 16354]]

follow-up of the cohort might be necessary due to the long latency 
period of silicosis (2013, Document ID 3843, p. 1032).
    Follow-up time is a critical factor for detection of silicosis, 
which has a typical latency of 20-30 years (see Morfeld et al., 2013, 
Document ID 3843, p. 1028). As stated in Section V.C, Summary of the 
Review of Health Effects Literature and Preliminary QRA, the disease 
latency for silicosis can extend to around 30 years. Follow-up was 
extremely limited in the German porcelain workers silicosis morbidity 
analysis, with a mean of 7.5 years of follow up for the study 
population (Document ID 3843). Despite the limited follow-up time, the 
cohort showed evidence of silicosis morbidity among low-exposed 
workers: 17.5 percent of cases occurred among workers whose highest 
average silica exposure in any year (``highest annual'') was estimated 
by the authors to be less than 250 [mu]g/m\3\, and 12.5 percent of 
cases occurred among workers whose highest annual silica exposure was 
estimated at less than 100 [mu]g/m\3\ (Document ID 3843).
    The lead author of the study, Dr. Peter Morfeld, testified at the 
public hearings on behalf of the ACC Crystalline Silica Panel. In his 
post-hearing comments, Dr. Morfeld stated that ``[m]echanistic 
considerations imply that we should not expect to see a threshold for 
cumulative exposure'' in silicosis, but that the question of whether a 
threshold concentration level may exist remains (Document ID 4003, p. 
3). The study by Morfeld et al. ``focused on the statistical estimation 
of a concentration threshold . . . [and] simultaneously took into 
account the cumulative exposure to respirable crystalline silica dust 
as a driving force of the disease'' (Document ID 4003, p. 3). Morfeld 
et al. applied a technique developed by Ulm et al. (1989, 1991) to 
estimate a concentration threshold. In this method a series of 
candidate exposure concentration values are subtracted from the 
estimated annual mean concentration data. Using the recalculated 
exposure estimates for the study population, regression analyses for 
each candidate are run to identify the best fitting model, using the 
Akaike Information Criterion (AIC) to evaluate model fit (Document ID 
3843, p. 1029). According to Morfeld, the best fitting model in their 
study estimated a threshold concentration of 250 [mu]g/m\3\ (AIC = 
488.3) with a 95 percent confidence interval of 160 to 300 [mu]g/m\3\. 
A second model with very similar fit (AIC = 488.8) estimated a 
threshold concentration of 200 [mu]g/m\3\ with a 95 percent confidence 
interval of 57 [mu]g/m\3\ to 270 [mu]g/m\3\. A third model with a 
poorer fit (AIC=490.6) estimated a threshold concentration of 80 [mu]g/
m\3\ with a 95 percent confidence interval of 0.2 [mu]g/m\3\ to 210 
[mu]g/m\3\ (Document ID 3843, Table 3, p. 1031).
    In the Final Peer Review Report, Dr. Crump stated that Morfeld et 
al.'s modeling approach, like ``all such attempts statistically to 
estimate a threshold,'' is ``not reliable because the threshold 
estimates so obtained are highly unstable'' (Document ID 3574, p. 17). 
Dr. Morfeld's co-author, Dr. Mundt, stated in the public hearings:

    I'll be the first one to tell you there is a lot of imprecision 
and, therefore, say confidence intervals or uncertainty should be 
respected, and that the--I'm hesitant to just focus on a single 
point number like the .25 [250 [mu]g/m\3\], and prefer that you 
encompass the broader range that was reported in the Morfeld, on 
which I was an author and consistently brought this point to the 
table (Document ID 3577, Tr. 645).

    NIOSH submitted post-hearing comments on the analysis in Morfeld et 
al. (2013). NIOSH pointed out that the exposure measurements in the 
analysis were based on German dust samplers, which for pottery have 
been shown to collect approximately twice as much dust as U.S. 
samplers. Therefore, ``when Dr. Morfeld cited 0.15 mg/m\3\ (150 [mu]g/
m\3\) as the lower 95% confidence limit for the threshold, that would 
convert to 0.075 mg/m\3\ (75 [mu]g/m\3\) in terms of equivalent 
measurements made with a U.S. sampler'' (Document ID 4233, p. 21). 
Similarly, the U.S. equivalent of each of the other threshold estimates 
and confidence limits presented in Morfeld et al.'s analysis would be 
about half the reported exposure levels. NIOSH also commented that 
Morfeld et al.'s analysis appears to be consistent with both threshold 
and non-threshold models (Document ID 4233, p. 55). Furthermore, NIOSH 
observed that Morfeld et al. did not account for uncertainty in the 
values of one of their model parameters ([egr]); therefore their 
reported threshold confidence limits of 0.16-0.30 are too narrow 
(Document ID 4233, p. 56). More generally, NIOSH noted that Morfeld et 
al. did not quantitatively evaluate how uncertainty in exposure 
estimates may have impacted the results of the analysis; Morfeld agreed 
that he had not performed a ``formal uncertainty analysis'' (Document 
ID 4233, p. 58; 3582, Tr. 2078-2079). NIOSH concluded, ``it is our firm 
recommendation to discount results based on the model specified in 
[Morfeld et al. Eq. 3] . . . including all results related to a 
threshold'' (Document ID 4233, p. 58). OSHA has evaluated NIOSH's 
comments on the analysis and agrees that the issues raised by NIOSH 
raise serious questions about Morfeld et al.'s conclusions regarding a 
silica threshold.
    OSHA's greater concern with Dr. Morfeld's estimate of 250 [mu]g/
m\3\ as a threshold concentration for silicosis is the fact that a 
substantial proportion of workers with silicosis in Dr. Morfeld's study 
had no estimated exposure above the threshold suggested by the authors; 
this threshold was characterized by commenters, including the Chamber 
of Commerce (Chamber), as a concentration ``below which the lung 
responses did not progress to silicosis'' (Document ID 4224, Attachment 
1, p. 3). This point was emphasized by Dr. Brian Miller in the Final 
Peer Review Report (Document ID 3574, p. 57) and by NIOSH (Document ID 
4233, p. 57). In the study, 17.5 percent of workers with silicosis were 
classified as having no exposure above Morfeld et al.'s estimated 
threshold of 250 [mu]g/m\3\, (Document ID 3843, p. 1031) and 12.5 
percent of these workers were classified as having no exposure above 
100 [mu]g/m\3\. OSHA believes the presence of these low-exposed workers 
with silicosis clearly contradicts the authors' estimate of 250 [mu]g/
m\3\ as a level of exposure below which no worker will develop 
silicosis (see Document ID 4233, p. 57).
    In a post-hearing comment, Dr. Morfeld offered a different 
interpretation of his results, describing his threshold estimate as a 
``population average'' which would not be expected to characterize risk 
for all individuals in a population. Rather, according to Dr. Morfeld 
``we expect to see differences in response thresholds among subjects'' 
(Document ID 4003, p. 5). OSHA agrees with this interpretation, which 
was similarly expressed in several comments from OSHA's peer reviewers 
on the subject of thresholds (e.g., Document ID 3574, pp. 13, 21-22). 
Consistent with its peer reviewers' opinions, OSHA draws the conclusion 
from the data and discussion concerning population averages that these 
``differences in response thresholds among subjects'' support setting 
the PEL at 50 [mu]g/m\3\ in order to protect the majority of workers in 
the population of employees exposed to respirable crystalline silica. 
OSHA's review of the Morfeld et al. data on German porcelain workers 
thus reinforces its view that reducing exposures to this level will 
benefit the many workers who would develop silicosis at exposure levels 
below that of the ``average'' worker.
    Dr. Morfeld's discussion of his estimate as a ``population 
average'' among workers with different individual responses to silica 
exposure

[[Page 16355]]

echoes several comments from OSHA's peer reviewers on the subject of 
thresholds. In the Final Peer Review Report, Dr. Ginsberg observed that 
a linear exposure-response model may reflect a distribution of 
individual ``thresholds,'' such that ``the population can be 
characterized as having a distribution of vulnerability. This 
distribution may be due to differences in levels of host defenses that 
come with differences in age, co-exposure to other chemicals, the 
presence of interacting background disease processes, non-chemical 
stressors, and a variety of other host factors'' (Document ID 3574, p. 
21). Given the number of factors that may influence vulnerability to 
certain diseases in a population of workers, Dr. Ginsberg continued:

it is logical for OSHA to strongly consider inter-subject 
variability . . . as the reason for linearly-appearing regression 
slopes in silica-related non-cancer and cancer studies. This 
explanation does not imply an artifact [that is, a false appearance 
of linear exposure-response] but that the linear (or log linear) 
regression coefficient extending down to low dose reflects the 
inherent variability in susceptibility such that the effect of 
concern . . . may occur in some individuals at doses well below what 
might be a threshold in others (Document ID 3574, pp. 21-22).

    Peer reviewer Mr. Bruce Allen agreed that ``[i]t makes no sense to 
discuss a single threshold value . . . Given, then, that thresholds 
must be envisioned as a distribution in the population, then there is 
substantial population-level risk even at the mean threshold value, and 
unacceptably high risk levels at exposures far below the mean 
threshold.'' He further stated:

    It is NOT, therefore, inappropriate to model the population-
level observations using a non-threshold model . . . In fact, I 
would claim that it is inappropriate to include ANY threshold models 
(i.e., those that assume a single threshold value) when modeling 
epidemiological data. A non-threshold model for characterizing the 
population dose-response behavior is theoretically and practically 
the optimal approach (Document ID 3574, p. 13).

    OSHA concludes that this German porcelain workers cohort shows 
evidence of silicosis among workers exposed at levels below the 
previous PELs, and that continued follow-up of this cohort would be 
likely to show greater silicosis risk among low-exposed workers due to 
the short follow-up time. Furthermore, the Chamber's characterization 
of Dr. Morfeld's result as ``a threshold concentration of 250 [mu]g/
m\3\ below which the lung responses did not progress to silicosis'' 
(Document ID 4224, p. 3) is plainly inaccurate, as the estimated 
exposures of a substantial proportion of the workers with silicosis in 
the data set did not exceed this level.
e. Park et al. (2002)
    The ACC submitted comments on the Park et al. (2002, Document ID 
0405) study which examined silicosis and lung disease other than cancer 
(i.e., NMRD) in a cohort of diatomaceous earth workers. The ACC's 
comments on this study are discussed in detail in Section V.D, Comments 
and Responses Concerning Silicosis and Non-Malignant Respiratory 
Disease Mortality and Morbidity, including comments relating to 
exposure-response thresholds in this study. Briefly, the ACC claimed 
that the Park et al. (2002) study is ``fully consistent'' with 
Morfeld's estimate of a threshold above the 100 [mu]g/m\3\ 
concentration for NMRD, including silicosis, mortality (Document ID 
2307, Attachment A, p. 107). However, NIOSH explained in its post-
hearing brief that categorical analysis for NMRD indicated no threshold 
existed at or above a cumulative exposure corresponding to 25 [mu]g/
m\3\ over 40 years of exposure, which is below the cumulative exposure 
equivalent to the new PEL over 45 years (Document ID 4233, p. 27). Park 
et al. did not attempt to estimate a threshold below that level because 
the data lacked the power needed to discern a threshold (Document ID 
4233, p. 27). OSHA agrees with NIOSH's assessment, which indicates 
that, if there is a cumulative exposure threshold for NMRD, including 
silicosis, it is significantly below the final PEL of 50 [mu]g/m\3\.
f. Conclusion--Silicosis and NMRD
    OSHA concludes that the body of epidemiological literature clearly 
demonstrates risk of silicosis and NMRD morbidity and mortality among 
workers who have been exposed to cumulative exposures or average 
exposure concentrations at or below the levels associated with the 
previous general industry PEL (100 [mu]g/m\3\, or cumulative exposure 
of 4.5 mg/m\3\-yrs). Thus, OSHA does not agree with commenters who have 
stated that the previous general industry PEL is fully protective and 
that reducing it will yield no health benefits to silica-exposed 
workers (e.g., Document ID 4224, p. 2-5; Tr. 3582, pp. 1951-1963). 
Instead, the Agency finds that the evidence is at least as consistent 
with a finding that no threshold is discernible as it is with a finding 
that a threshold exists at some minimal level of exposure. The best 
available evidence also demonstrates silicosis morbidity and mortality 
below the previous PEL of 100 [mu]g/m\3\, indicating that any threshold 
for silicosis (understood as an exposure level below which no one would 
develop disease), if one exists, is below that level. Even if the 
conclusion reached by Dr. Morfeld that a population average threshold 
exists above the level of the previous PEL is accurate, there will 
still be a substantial portion of the population who will develop 
silicosis from exposures below the identified ``threshold.'' These 
findings support OSHA's action in lowering the PEL to 50 [mu]g/m\3\.
3. Thresholds--Lung Cancer
    OSHA's Preliminary QRA and supplemental literature review included 
several studies that provide information on possible threshold effects 
for lung cancer. OSHA has determined that the epidemiological studies 
most relevant to the threshold issue are those with workers who have 
cumulative exposures or average exposure concentrations below the 
levels associated with the previous general industry PEL (100 [mu]g/
m\3\, or cumulative exposure of 4.5 mg/m\3\-yrs). As with the silicosis 
studies previously discussed, contrary to comments that OSHA only 
relied on studies involving exposures far above the levels of interest 
to OSHA in this rulemaking (e.g., Document ID 2307, Attachment A, pp. 
94-95; 4226, p. 2), a number of lung cancer studies included workers 
who were exposed at levels close to or below the previous general 
industry PEL. Five of the 10 cohorts of workers in the pooled lung 
cancer risk analysis conducted by Steenland et al. (2001a) had median 
cumulative exposures below 4.5 mg/m\3\-yrs (the cumulative level 
associated with a working lifetime of exposure at the previous general 
industry PEL); four were also below 2.25 mg/m\3\-yrs (the cumulative 
level associated with a working lifetime of exposure at the revised 
PEL) and three had median silica concentrations below 100 [mu]g/m\3\ 
(Document ID 0452, p. 775). Other lung cancer studies with significant 
numbers of relatively low-exposed workers include analyses of the 
Vermont granite workers (Attfield and Costello, 2004, Document ID 0285; 
Vacek et al., 2011, 1486) and industrial sand workers (McDonald et al., 
2001, Document ID 1091; Hughes et al., 2001, 1060; McDonald et al., 
2005, 1092) described in the previous discussion on silicosis. In 
addition to the epidemiological studies discussed here, in Section V.H, 
Mechanisms of Silica-Induced Adverse Health Effects, OSHA discussed 
studies that have shown direct genotoxic mechanisms by which exposure 
to crystalline silica at any level, with no threshold effect, may lead 
to lung cancer.

[[Page 16356]]

a. Steenland et al. Pooled Lung Cancer Study and Related Analyse
    Steenland et al. (2001a) estimated excess lifetime risk of lung 
cancer based on a 10-cohort pooled study, which included several 
cohorts with significant numbers of workers with median cumulative and 
average exposures below those allowed by the previous general industry 
PEL (Document ID 0452). Results indicated that 45 years of exposure at 
0.1 mg/m\3\ (100 [mu]g/m\3\) would result in a lifetime risk of 28 
excess lung cancer deaths per 1,000 workers (95% confidence interval 
(CI) 13-46 per 1,000). An alternative (non-linear) model yielded a 
lower risk estimate of 17 per 1,000 (95% CI 2-36 per 1,000).
    A follow-up letter by Steenland and Deddens (2002, Document ID 
1124) addressed the possibility of an exposure threshold effect in the 
pooled lung cancer analysis conducted by Steenland et al. in 2001. 
According to Dr. Steenland, ``We further investigated whether there was 
a level below which there was no increase in risk, the so-called 
threshold. So we fit models that had a threshold versus those that 
didn't, and we explored various thresholds that might apply'' (Document 
ID 3580, Tr. 1229). Threshold models using average exposure and 
cumulative exposure failed to show a statistically significant 
improvement in fit over models without a threshold. However, the 
authors found that when they used the log of cumulative exposure (a 
transformation commonly used to reduce the influence of high exposure 
points on a model), a threshold model with a 15-year lag fit better 
than a no-threshold model. The authors reported the best threshold 
estimate at 4.8 log mg/m\3\-days (Document ID 1124, p. 781), or an 
average exposure of approximately 10 [mu]g/m\3\ over a 45-year working 
lifetime, one-fifth of the final PEL. Dr. Steenland explained what his 
analysis indicated regarding a cumulative exposure threshold for lung 
cancer: ``we found, in fact, that there was a threshold model that fit 
better than a no-threshold model, not enormously better but better 
statistically, but that threshold was extremely low . . . far below the 
. . . silica standard proposed by OSHA'' (Document ID 3580, Tr. 1229).
    In response to comments from ACC Panel members Dr. Valberg and Dr. 
Long that the analysis presented by Steenland et al. showed a clear 
threshold at a level of cumulative exposure high enough to bear on 
OSHA's choice of PEL (Document ID 2330, p. 20), Dr. Steenland explained 
that their conclusion was based on a misreading of an illustration in 
his study:

    [I]f you look at the figure, you see that the curve of the 
spline [a flexible, nonlinear exposure-response model] starts to go 
up around four on the log scale of microgram per meter cubed days. 
And if you transform that from the log to the regular scale, that is 
quite consistent with the threshold we got when we did a formal 
analysis using the log transform model [discussed above] (Document 
ID 3580, Tr. 1255).

    The ACC representatives' comments do appear to be based on a 
misunderstanding of the figure in question, due to an error in Dr. 
Steenland's 2001 publication in which the axis of the figure under 
discussion was incorrectly labeled. This error was later corrected in 
an erratum (Document ID 3580, Tr. 1257; Steenland et al., 2002, 
Erratum. Cancer Causes Control, 13:777).
    In addition, at OSHA's request, Drs. Steenland and Bartell 
(ToxaChemica, 2004, Document ID 0469) conducted a quantitative 
uncertainty analysis to examine the effects of possible exposure 
measurement error on the pooled lung cancer study results (see Section 
V.K, Comments and Responses Concerning Exposure Estimation Error and 
ToxaChemica's Uncertainty Analysis). These analyses showed no evidence 
of a threshold effect for lung cancer at the final or previous PELs. 
Based on Dr. Steenland's work, therefore, OSHA believes that no-
threshold models are appropriate for evaluating the exposure-response 
relationship between silica exposure and lung cancer. Even if 
commenters are correct that threshold models are preferable, the 
threshold is likely at a level of cumulative exposure significantly 
below what a worker would accumulate in 45 years of exposure at the 
final PEL, and is therefore immaterial to this rulemaking (see Document 
ID 1124, p. 781).
b. Vermont Granite Workers
    In the Preliminary QRA and supplemental literature review, OSHA 
reviewed several studies on lung cancer among silica-exposed workers in 
the Vermont granite industry, whose exposures were reduced to 
relatively low levels due to a program for dust control initiated in 
1938-1940 by the Vermont Division of Industrial Hygiene (Document ID 
1711, pp. 97-102; 1711, Attachment 1, pp. 2-5; 1487, p. 73). As 
discussed above, Verma et al. (2012) reported that all jobs in the 
industry had average exposure concentrations at or below 100 [mu]g/
m\3\--most of them well below this level--in the time period 1950-2004 
after implementation of exposure controls (Document ID 1487, Table IV, 
p. 75).
    Attfield and Costello (2004) examined a cohort of 5,414 Vermont 
granite workers, including 201 workers who died of lung cancer 
(Document ID 0285, pp. 130, 134). In this study, cancer risk was 
elevated at cumulative exposure levels below 4.5 mg/m\3\-yrs, the 
amount of exposure that would result from a 45-year working lifetime of 
exposure at the previous PEL. The authors reported elevated lung cancer 
in all exposure groups, observing statistically significant elevation 
among workers with cumulative exposures between 0.5 and 1 mg/m\3\-yrs 
(p < 0.05), cumulative exposures between 2 and 3 mg/m\3\-yrs (p < 
0.01), and cumulative exposures between 3 and 6 mg/m\3\-yrs (p < 0.05) 
(Document ID 0285, p. 135). These findings indicate that a threshold in 
exposure-response for lung cancer is unlikely at cumulative exposure 
levels associated with 45 years of exposure at the previous PEL and 
below.
    Vacek et al. (2011) examined a group of 7,052 men, overlapping with 
the Attfield and Costello cohort, who worked in the Vermont granite 
industry at any time between January 1, 1947 and December 31, 1998 
(Document ID 1486). Like Attfield and Costello, Vacek et al. reported 
significantly elevated lung cancer (p < 0.01) (Document ID 1486, p. 
315). Most of the lung cancer cases in Vacek et al. (305/356) had 
cumulative exposures less than or equal to 4.1 mg/m\3\-yrs (Document ID 
1486, p. 316), below the cumulative exposure level of 4.5 mg/m\3\-yrs 
associated with 45 years of exposure at the previous PEL and below. 
However, unlike Attfield and Costello, Vacek et al. did not find a 
statistically significant relationship of increasing lung cancer risk 
with increasing silica exposure, leading Vacek et al. to conclude that 
increased lung cancer mortality in the cohort may not have been due to 
silica exposure (Document ID 1486, p. 312).
    The strengths and weaknesses of both studies and the differences 
between them that could account for their conflicting conclusions were 
discussed in great detail in Section V.F, Comments and Responses 
Concerning Lung Cancer Mortality. For the purpose of evaluating the 
effects of low concentrations of silica exposure, as well as whether a 
threshold exposure exists, OSHA believes the Attfield and Costello 
study may merit greater weight than Vacek et al. As discussed in 
Section V.F, Comments and Responses Concerning Lung Cancer Mortality, 
OSHA believes Attfield and Costello's choice to exclude the highest 
exposure group from their analysis likely improved their study's

[[Page 16357]]

estimate of the exposure-response relationship at lower exposures; by 
making this choice, they limited the influence of highly uncertain 
exposure estimates at higher levels and helped to reduce the impact of 
the healthy worker survivor effect. The Agency acknowledges the 
strengths of the Vacek et al. analysis as well, including longer 
follow-up of workers.
    In conclusion, OSHA does not find compelling evidence in these 
studies of Vermont granite workers of a cumulative exposure threshold 
for lung cancer in the exposure range below the previous general 
industry PEL. This conclusion is based on the statistically significant 
elevations in lung cancer reported in both cohorts described above, 
which were composed primarily of workers whose cumulative exposures 
were below the level associated with a working lifetime of exposure. 
However, OSHA acknowledges that a strong conclusion regarding a 
threshold is difficult to draw from these studies, due to the 
disagreement between Attfield and Costello and Vacek et al. regarding 
the likelihood that excess lung cancer among Vermont granite workers 
was due to their silica exposures.
c. Industrial Sand Workers
    OSHA's Preliminary QRA (Document ID 1711, pp. 285-287) evaluated a 
2001 case-control analysis of industrial sand workers including 2,640 
men employed before 1980 for at least three years in one of nine North 
American sand-producing plants. One of the sites was a large associated 
office complex where workers' exposures were lower than those typically 
experienced by production workers (Hughes et al., 2001, Document ID 
1060). A later update by McDonald et al. (2005, Document ID 1091) 
eliminated one plant, following 2,452 men from the 8 remaining U.S. 
plants. Both cohorts overlapped with an earlier industrial sand cohort, 
including 4,626 workers at 18 plants, which was included in Steenland 
et al.'s pooled analysis (2001a, Document ID 0452). OSHA noted that 
these studies (Hughes et al., 2001, Document ID 1060; McDonald et al., 
2005, 1092; Steenland and Sanderson, 2001, 0455) showed similar 
exposure-response patterns of increased lung cancer mortality with 
increased exposure.
    In the Final Peer Review Report, Dr. Ginsberg commented on the 
relevance of the industrial sand cohort studies, which included low-
exposed workers with exceptionally well-characterized exposures, for 
threshold issues:

    With respect to the body of silica epidemiology literature, 
perhaps the case with the least amount of measurement error is of US 
industrial sand workers wherein many measurements were made with 
filter samples and SRD determination of crystalline silica and in 
which there was very careful estimation of historical exposure for 
both silica and smoking (MacDonald et al. 2005; Steenland and 
Sanderson 2001; Hughes et al. 2001) (Document ID 3574, pp. 22-23).

    OSHA agrees with Dr. Ginsberg's assessment of these studies and has 
found them to be particularly high quality. Thus, the Agency was 
especially interested in the studies' findings, which showed that 
cancer risk was elevated at cumulative exposure levels below 4.5 mg/
m\3\-yrs, the amount of exposure that would result from a 45-year 
working lifetime of exposure at the previous PEL. OSHA believes these 
results provide strong evidence against a threshold in cumulative 
exposure at any level high enough to impact OSHA's choice of PEL. Dr. 
Ginsberg agrees with OSHA's conclusion (Document ID 3574, p. 23).
d. Other Studies
    Comments submitted by the ACC briefly mentioned several 
epidemiological studies that, they claim, ``suggest the existence of a 
threshold for any increased risk of silica-related lung cancer,'' 
including studies by Sogl et al. (2012), Mundt et al. (2011), Pukkala 
et al. (2005), Calvert et al. (2003), Checkoway et al. (1997), and 
Steenland et al. (2001a). OSHA previously reviewed several of these 
studies in the Review of Health Effects Literature and Preliminary 
Quantitative Risk Assessment, and the Supplemental Literature Review, 
though not with specific attention to their implications for exposure-
response thresholds (Document ID 1711, pp. 139-155; 1711, Attachment 1, 
pp. 6-12). The studies cited by ACC are discussed below, with the 
exception of Steenland et al. (2001a), which was previously reviewed in 
this section.
e. German Porcelain Workers
    OSHA reviewed Mundt et al. (2011, Document ID 1478) in its 
Supplemental Literature Review (Document ID 1711, Attachment 1, pp. 6-
12). As discussed there, Mundt et al. examined the risks of silicosis 
morbidity and lung cancer mortality in a cohort of 17,644 German 
porcelain manufacturing workers who had participated in medical 
surveillance programs for silicosis between 1985 and 1987. This cohort 
was also examined in a previous paper by Birk et al. (2009, Document ID 
4002, Attachment 2).
    Quantitative exposure estimates for this cohort showed an average 
annual exposure of 110 [mu]g/m\3\ for workers hired prior to 1960 and 
an average of 30 [mu]g/m\3\ for workers hired after 1960. More than 40 
percent of the cohort had cumulative exposures less than 0.5 mg/m\3\-
yrs at the end of follow-up, and nearly 70 percent of the cohort had 
average annual exposures less than 50 [mu]g/m\3\ (Mundt et al., 2011, 
Document ID 1478, pp. 283-284).
    The lung cancer mortality hazard ratios (HRs) associated with 
average annual exposure were statistically significant in two of the 
four average annual exposure groups: 2.1 (95% CI 1.1-4.0) for average 
annual exposure group >50-100 [mu]g/m\3\ and 2.4 (95% CI 1.1-5.2) for 
average annual exposure group >150-200 [mu]g/m\3\, controlling for age, 
smoking, and duration of employment. In contrast, the HRs for lung 
cancer mortality associated with cumulative exposure were not 
statistically elevated after controlling for age and smoking.
    The authors suggested the possibility of a threshold for lung 
cancer mortality. However, no formal threshold analysis for lung cancer 
was conducted in this study or in the follow-up threshold analysis 
conducted on this population by Morfeld et al. for silicosis (2013, 
Document ID 4175). Having reviewed this study carefully, OSHA believes 
it is inconclusive on the issue of thresholds due to the elevated risk 
of lung cancer seen among low-exposed workers (for example, those with 
average exposures of 50-100 [mu]g/m\3\), which is inconsistent with the 
ACC's claim that a threshold exists at or above the previous PEL of 100 
[mu]g/m\3\, and due to several limitations which may preclude detection 
of a relationship between cumulative exposure and lung cancer in this 
cohort. As discussed in the Preliminary QRA, these include: (1) A 
strong healthy worker effect observed for lung cancer; (2) Mundt et al. 
did not follow the typical convention of considering lagged exposures 
to account for disease latency; and (3) the relatively young age of 
this cohort (median age 56 years old at time of silicosis 
determination) (Document ID 1478, p. 288) and limited follow-up period 
(average of 19 years per subject) (Birk et al. 2009, Document ID 4002, 
Attachment 2, p. 377). Only 9.2 percent of the cohort was deceased by 
the end of the follow up period. Mundt et al. (2011) acknowledged this 
limitation, stating that the lack of increased risk of lung cancer was 
a preliminary finding (Document ID 1478, p. 288).
f. German Uranium Miners
    In pre-hearing comments, Dr. Morfeld described a study of 58,677 
German uranium miners by Sogl et al. (2012,

[[Page 16358]]

Document ID 3842; 2307, Attachment 2, p. 11). Dr. Morfeld noted that 
the study was based on a detailed exposure assessment of respirable 
crystalline silica (RCS) dust. According to Dr. Morfeld, Sogl et al. 
``showed that no lung cancer excess risk was observed at RCS dust 
exposure levels below 10 mg/m\3\-years'' (Document ID 2307, Attachment 
2, p. 11). OSHA's review of this publication confirmed that the authors 
reported a spline function with a single knot at 10 mg/m\3\-yrs, which 
Morfeld interprets to suggest a threshold for lung cancer of 
approximately 250 [mu]g/m\3\ average exposure concentration for workers 
exposed over the course of 40 years. However, the authors also noted 
that an increase in risk below this level could not be ruled out due to 
strong confounding with radon, resulting in possible over-adjustment 
(Sogl et al., Document ID 3842, p. 9). That is, because workers with 
high exposures to silica would also have had high exposures to the lung 
carcinogen radon, the models used by Sogl et al. may have been unable 
to detect a relationship between silica and lung cancer in the presence 
of radon. As described previously, excess lung cancer has been observed 
among workers with lower cumulative exposures than the Sogl et al. 
``threshold'' in other studies which do not suffer from confounding 
from potent lung carcinogens other than silica (for example, industrial 
sand workers), and which are, therefore, likely to provide more 
reliable evidence on the issue of thresholds. OSHA concludes that the 
Sogl et al. study does not provide convincing evidence of a cumulative 
exposure threshold for lung cancer.
g. U.S. Diatomaceous Earth Workers
    Checkoway et al. (1997) investigated the risk of lung cancer among 
diatomaceous earth (DE) workers exposed to respirable cristobalite (a 
type of silica found in DE) (Document ID 0326; 1711, pp. 139-143). 
Exposure samples were collected primarily at one of the two plants in 
the study by plant industrial hygienists over a 40-year timeframe from 
1948 to 1988 and used to estimate exposure for each individual in the 
cohort (Seixas et al., 1997, Document ID 0431, p. 593). Based on 77 
deaths from cancer of the trachea, lung, and bronchus, the standardized 
mortality ratios (SMR) were 129 (95% CI 101-161) and 144 (95% CI 114-
180) based on rates for U.S. and local county males, respectively 
(Document ID 0326, pp. 683-684). The authors found a positive, but not 
monotonic, exposure-response trend for lung cancer. The risk ratios for 
lung cancer with increasing quintiles of respirable crystalline silica 
exposure were 1.00, 0.96, 0.77, 1.26 and 2.15 with a 15-year exposure 
lag. Lung cancer mortality was thus elevated for workers with 
cumulative exposures greater than 2.1 mg/m\3\-yrs, but was only 
statistically significantly elevated for the highest exposure category 
(RR = 2.15; 95% CI 1.08-4.28) (Document ID 0326, p. 686). OSHA notes 
that this highest exposure category includes cumulative exposures only 
slightly higher than 4.5 mg/m\3\-yrs, the level of cumulative exposure 
resulting from a 45-year working lifetime at the previous PEL of 100 
[mu]g/m\3\. OSHA does not believe that the appearance of a 
statistically significantly elevated lung cancer risk in the highest 
category should be interpreted as evidence of an exposure-response 
threshold, especially in light of the somewhat elevated risk seen at 
lower exposure levels. OSHA believes it is more likely to reflect 
limited power to detect excess risk at lower exposure levels, a common 
issue in epidemiological studies which was emphasized by peer reviewer 
Dr. Andrew Salmon in relation to purported thresholds (Document ID 
3574, p. 37).
h. Finnish Nationwide Job Exposure Matrix
    OSHA reviewed Pukkala et al. (2005, Document ID 0412) in the Review 
of Health Effects Literature and Preliminary Quantitative Risk 
Assessment (Document ID 1711, pp. 153-154). As discussed there, Pukkala 
et al. (2005) evaluated the occupational silica exposure among all 
Finns born between 1906 and 1945 who participated in a national 
population census on December 31, 1970. Follow-up of the cohort was 
through 1995. Between 1970 and 1995, there were 30,137 cases of 
incident lung cancer among men and 3,527 among women. Exposure data 
from 1972 to 2000 was collected by the Finnish Institute of 
Occupational Health (FIOH). Cumulative exposure categories for 
respirable quartz were defined as: <1.0 mg/m\3\-yrs (low), 1.0-9.9 mg/
m\3\-yrs (medium) and >10 mg/m\3\-yrs (high). For men, over 18 percent 
of the 30,137 lung cancer cases worked in occupations with potential 
exposure to silica dust. The cohort showed statistically significantly 
increased lung cancer among men in the lowest occupationally exposed 
group (those with less than 1.0 mg/m\3\-yrs cumulative silica 
exposure), as well as for men with exposures in the two higher groups 
(1.0-9.9 mg/m\3\-yrs and >10 mg/m\3\-yrs). For women, the cohort showed 
statistically significantly increased lung cancer among women with at 
least 1.0 mg/m\3\-yrs cumulative silica exposure. Given these results, 
it is unclear why ACC stated that Pukkula's results suggest that 
``excess risk of lung cancer is mainly attributable to . . . cumulative 
exposure exceeding 10 mg/m\3\-years'' (Document ID 4209, p. 54). 
Indeed, Pukkula's analysis appears to show excess risk of lung cancer 
among men with any level of occupational exposure and among women whose 
cumulative exposures were quite low (at least equivalent to about 25 
[mu]g/m\3\ over 45 years). It does not support the ACC's contention 
that lung cancer is seen primarily in workers with exposures greater 
than 200 [mu]g/m\3\ (Document ID 4209, p. 54), but rather suggests that 
any threshold for lung cancer risk would likely be well below 100 
[mu]g/m\3\.
i. U.S. National (27 states) Case-Control Study
    As discussed in the Review of Health Effects Literature and 
Preliminary Quantitative Risk Assessment (Document ID 1711, pp. 152-
153), Calvert et al. (2003, Document ID 3890) conducted a case-control 
study using 4.8 million death certificates from the National 
Occupational Mortality Surveillance data set. Death certificates were 
collected from 27 states covering the period from 1982 to 1995. Cases 
were persons who had died from any of several diseases of interest: 
Silicosis, tuberculosis, lung cancer, chronic obstructive pulmonary 
disease (COPD), gastrointestinal cancers, autoimmune-related diseases, 
or renal disease. Worker exposure to crystalline silica was categorized 
as no/low, medium, high, or super-high based on their industry and 
occupation. The authors acknowledged the potential for confounding by 
higher smoking rates for cases compared to controls, and partially 
controlled for this by eliminating white-collar workers from the 
control group in the analysis. Following this adjustment, the authors 
reported weak, but statistically significantly elevated, lung cancer 
mortality odds ratios (OR) of 1.07 (95% CI 1.06-1.09) and 1.08 (95% CI 
1.01-1.15) for the high- and super-high exposure groups, respectively 
(Calvert et al., 2003, Document ID 3890, p. 126). Upon careful review 
of this study, OSHA maintains its position that it should not be used 
for quantitative risk analysis (including determination of threshold 
effects) because it lacks an exposure characterization based on 
sampling. Any determination regarding the existence or location of a 
threshold based on Calvert et al. (2003) must, therefore, be considered 
highly speculative.

[[Page 16359]]

j. Conclusion--Lung Cancer
    In conclusion, OSHA has determined that the best available evidence 
on the issue of a threshold for silica-related lung cancer does not 
support the ACC's contention that an exposure-response threshold, below 
which respirable crystalline silica exposure is not expected to cause 
cancer, exists at or above the previous general industry PEL of 100 
[mu]g/m3. While there are some studies that claim to point 
to thresholds above the previous general industry PEL, multiple studies 
contradict this evidence, most convincingly through evidence that 
cohort members with low cumulative silica exposures suffered from lung 
cancer as a result of their exposure. These studies indicate that there 
is either no threshold for silica-related lung cancer, or that this 
threshold is at such a low level that workers cumulatively exposed at 
or below the level allowed by the new PEL of 50 [mu]g/m3 
will still be at risk of developing lung cancer. Thus, OSHA does not 
agree with commenters who have stated that the previous general 
industry PEL is fully protective and that reducing it will yield no 
health benefits to silica-exposed workers (e.g., Document ID 4224, p. 
2-5; Tr. 3582, pp. 1951-1963).
4. Exposure Uncertainty and Thresholds
    In his pre-hearing comments, Dr. Cox stated that the observation of 
a positive and monotonic exposure-response relationship in 
epidemiological studies ``does not constitute valid evidence against 
the hypothesis of a threshold,'' and that OSHA's findings of risk at 
exposures below the previous PEL for general industry ``could be due 
simply to exposure misclassification'' in studies of silica-related 
health effects in exposed workers (Document ID 2307, Attachment 4, pp. 
41-42). His statements closely followed his analyses from a 2011 paper, 
in which Cox presented a series of simulation analyses designed to show 
that common concerns in epidemiological analyses, such as uncontrolled 
confounding, errors in exposure estimates, and model specification 
errors, can obscure evidence of an exposure-response threshold, if such 
a threshold exists (Document ID 3600, Attachment 7). Dr. Cox concluded 
that the currently available epidemiological studies ``do not provide 
trustworthy information about the presence or absence of thresholds in 
exposure-response relations'' with respect to an exposure concentration 
threshold for lung cancer (Document ID 3600, Attachment 7, p. 1548).
    OSHA has reviewed Dr. Cox's comments and testimony, and concludes 
that uncertainty about risk due to exposure estimation and confounding 
cannot be resolved through the application of the statistical 
procedures recommended by Dr. Cox. (Similar comments from Dr. Cox about 
alleged biases in the studies relied upon are addressed in the next 
section, where OSHA reaches similar conclusions). A reviewer on the 
independent peer review panel, Dr. Ginsberg, commented that:

epidemiology studies will always have issues of exposure 
misclassification or other types of error that may create 
uncertainty when it comes to model specification. However, these 
types of error will also bias correlations to the null such that if 
they were sufficiently influential to obscure a threshold they may 
also substantially weaken regression results and underestimate the 
true risk (Document ID 3574, p. 23).

    OSHA agrees with Dr. Ginsberg. As discussed in Section V.K, 
Comments and Responses Concerning Exposure Estimation Error and 
ToxaChemica's Uncertainty Analysis, a ``gold standard'' exposure sample 
is not available for the epidemiological studies in the silica 
literature, so it is not possible to determine the direction or 
magnitude of the effects of exposure misclassification on OSHA's risk 
estimates. The silica literature is not unique in this sense. As stated 
by Mr. Robert Park of NIOSH, ``modeling exposure uncertainty as 
described by Dr. Cox . . . is infeasible in the vast majority of 
retrospective observational studies. Nevertheless, mainstream 
scientific thought holds that valid conclusions regarding disease 
causality can still be drawn from such studies'' (Document ID 4233, p. 
32).
    For the reasons discussed throughout this analysis of the 
scientific literature, OSHA concludes that, even acknowledging a 
variety of uncertainties in the studies relied upon, these 
uncertainties are, for the most part, typical or inherent in these 
types of studies. OSHA therefore finds that the weight of evidence in 
these studies, representing the best available evidence on the health 
effects of silica exposure, strongly supports the findings of 
significant risk from silicosis, NMRD, lung cancer, and renal disease 
discussed in this section and in the quantitative risk assessment that 
follows in the next section (see Benzene, 448 U.S. at 656 (``OSHA is 
not required to support its finding that a significant risk exists with 
anything approaching scientific certainty. Although the Agency's 
findings must be supported by substantial evidence, 29 U.S.C. 655(f), 
6(b)(5) specifically allows the Secretary to regulate on the basis of 
the `best available evidence.' '')).
5. Conclusion
    In summary, OSHA acknowledges that common issues with 
epidemiological studies limit the Agency's ability to determine whether 
and where a threshold effect exists for silicosis and lung cancer. 
However, as shown in the foregoing discussion, there is evidence in the 
epidemiological literature that workers exposed to silica at 
concentrations and cumulative levels allowable under the previous 
general industry PEL not only develop silicosis, but face a risk of 
silicosis high enough to be significant ( >1 per 1,000 exposed 
workers). Although the evidence is less clear for lung cancer, studies 
nevertheless show excess cases of lung cancer among workers with 
cumulative exposures in the range of interest to OSHA. Furthermore, the 
statistical model-based approaches proposed in public comments do not 
demonstrate the existence or location of a ``threshold'' level of 
silica exposure below which silica exposure is harmless to workers. The 
above considerations lead the Agency to conclude that any possible 
exposure threshold is likely to be at a low level, such that some 
workers will continue to suffer the health effects of silica exposure 
even at the new PEL of 50 [mu]g/m3.
    There is a great deal of argument and analysis directed at the 
question of thresholds in silica exposure-response relationships, but 
nothing like a scientific consensus about the appropriate approach to 
the question has emerged. If OSHA were to accept the ACC's claim that 
exposure to 100 [mu]g/m3 silica is safe for all workers (due 
to a threshold at or above an exposure concentration of 100 [mu]g/
m3) and set a PEL at 100 [mu]g/m3 for all 
industry sectors, and if that claim is in fact erroneous, the 
consequences of that error to silica-exposed workers would be grave. A 
large population of workers would remain at significant risk of serious 
occupational disease despite feasible options for exposure reduction.

J. Comments and Responses Concerning Biases in Key Studies

    OSHA received numerous comments and testimony, particularly from 
representatives of the ACC, regarding biases in the data that the 
Agency relied upon to conduct its Preliminary Quantitative Risk 
Assessment (Preliminary QRA). In this section, OSHA focuses on these 
comments regarding biases, particularly with respect to how such biases 
may have affected the data and findings from the

[[Page 16360]]

key peer-reviewed, published studies that OSHA relied upon in its 
Preliminary QRA.
    The data utilized by OSHA to conduct its Preliminary QRA came from 
published studies in the peer-reviewed scientific literature. When 
developing health standards, OSHA is not required or expected to 
conduct original research or wait for better data or new studies (see 
29 U.S.C. 655(b)(5); e.g., United Steelworkers v. Marshall, 647 F.2d 
1189, 1266 (D.C. Cir. 1980), cert. denied, 453 U.S. 913 (1981)). 
Generally, OSHA bases its determinations of significant risk of 
material impairment of health on the cumulative evidence found in a 
number of studies, no one of which may be conclusive by itself (see 
Public Citizen Health Research Group v. Tyson, 796 F.2d 1479, 1495 
(D.C. Cir. 1986) (reviewing courts do not ``seek a single dispositive 
study that fully supports the Administrator's determination . . . 
Rather, [OSHA's] decision may be fully supportable if it is based . . . 
on the inconclusive but suggestive results of numerous studies.''). 
OSHA's critical reading and interpretation of scientific studies is 
thus appropriately guided by the instructions of the Supreme Court's 
Benzene decision that ``so long as they are supported by a body of 
reputable scientific thought, OSHA is free to use conservative 
assumptions in interpreting the data with respect to carcinogens, 
risking error on the side of overprotection rather than 
underprotection'' (Industrial Union Dep't v. American Petroleum Inst., 
448 U.S. 607, 656 (1980)).
    Since OSHA is not a research agency, it draws from the best 
available existing data in the scientific literature to conduct its 
quantitative risk assessments. In most cases, with the exception of 
certain risk and uncertainty analyses prepared for OSHA by its 
contractor ToxaChemica, OSHA had no involvement in the data generation 
or analyses reported in those studies. Thus, in calculating its risk 
estimates, OSHA used published regression coefficients or equations 
from key peer-reviewed, published studies, but had no control over the 
actual published data; nor did the Agency have access to the raw data 
from such studies.
    As discussed throughout Section V of this preamble, the weight of 
scientific opinion indicates that respirable crystalline silica is a 
human carcinogen that causes serious, life-threatening disease at the 
previously-permitted exposure levels. Under its statutory mandate, the 
Agency can and does take into account the potential for statistical and 
other biases to skew study results in either direction. However, the 
potential biases of concern to the commenters are well known among 
epidemiologists. OSHA therefore believes that the scientists who 
conduct the studies and subject them to peer review before publication 
have taken the potential for biases into account in evaluating the 
quality of the data and analysis. As discussed further below, OSHA 
heard testimony from David Goldsmith, Ph.D., describing how scientists 
use ``absolutely the best evidence they can lay their hands on'' and 
place higher value on studies that are the least confounded by other 
factors that, if unaccounted for, could contribute to the effect (e.g., 
lung cancer mortality). (Document ID 3577, Tr. 894-895). Dr. Goldsmith 
also testified that many of the assertions of biases put forth in the 
rulemaking docket are speculative in nature, with no actual evidence 
presented (Document ID 3577, Tr. 901). Thus, while taking seriously the 
critiques of the ``body of reputable scientific thought'' OSHA has used 
to support this final silica standard, the Agency finds no reason, as 
discussed below, to consider discredited in any material way its key 
conclusions regarding causation or significant risk of harm.
    In his pre-hearing comments, Dr. Cox, on behalf of the ACC, claimed 
that the Preliminary QRA did not address a number of sources of 
potential bias:

    The Preliminary QRA and the published articles that it relies on 
do not correct for well-known biases in modeling statistical 
associations between exposures and response. (These include study, 
data, and model selection biases; model form specification and model 
over-fitting biases; biases due to residual confounding, e.g., 
because age is positively correlated with both cumulative exposure 
and risk of lung diseases within each age category (typically 5 or 
more years long); and biases due to the effects of errors in 
exposure estimates on shifting apparent thresholds to lower 
concentrations). As a result, OSHA has not demonstrated that there 
is any non-random association between crystalline silica exposure 
and adverse health responses (e.g., lung cancer, non-malignant 
respiratory disease, renal disease) at exposure levels at or below 
100 [[micro]g/m\3\]. The reported findings of such an association, 
e.g., based on significantly elevated relative risks or 
statistically significant positive regression coefficients for 
exposed compared to unexposed workers, are based on unverified 
modeling assumptions and on ignoring uncertainty about those 
assumptions (Document ID 2307, Attachment 4, pp. 1-2).

    These biases, according to Dr. Cox, nearly always result in false 
positives, i.e., finding that an exposure-response relationship exists 
when there really is no such relationship (Document ID 3576, Tr. 380). 
Although his comments appear to be directed to all published, peer-
reviewed studies relied upon by OSHA in estimating risks, Dr. Cox 
admitted at the hearing that his statements about false positives were 
based on his review of the Preliminary QRA with relation to lung cancer 
only, and that he ``[didn't] really know'' whether the same allegations 
of bias he directed at the lung cancer studies are relevant to the 
studies of silica's other health risks (Document ID 3576, Tr. 426). In 
his comments, Dr. Cox discussed each source of bias in detail; OSHA 
will address them in turn. The concerns expressed by commenters, 
including Dr. Cox, about exposure uncertainty--another potential source 
of bias--are addressed in Section V.K, Comments and Responses 
Concerning Exposure Estimation Error and ToxaChemica's Uncertainty 
Analysis.
1. Model Specification Bias
    Dr. Cox stated that model specification error occurs when the model 
form, such as the linear absolute risk model, does not correctly 
describe the data (Document ID 2307, Attachment 4, p. 21). Using a 
simple linear regression example from Wikipedia, Dr. Cox asserted that 
common indicators of goodness-of-fit, including sum of square residuals 
and correlation coefficients, can be weak in identifying 
``nonlinearities, outliers, influential single observations, and other 
violations of modeling assumptions'' (Document ID 2307, Attachment 4, 
pp. 52-53). He advocated for the use of diagnostic tests to check that 
a model is a valid and robust choice, stating, ``[u]nfortunately, 
OSHA's Preliminary QRA and the underlying papers and reports on which 
it relies are not meticulous in reporting the results of such model 
diagnostics, as good statistical and epidemiological practice 
requires'' (Document ID 2307, Attachment 4, p. 21). In his post-hearing 
brief, Dr. Cox further described these diagnostic tests to include 
plots of residuals, quantification of the effects of removing outliers 
and influential observations, and comparisons of alternative model 
forms using model cross-validation (Document ID 4027, p. 2). He also 
suggested using Bayesian Model Averaging (BMA) or other model ensemble 
methods to quantify the effects of model uncertainty (Document ID 4027, 
p. 3).
    OSHA believes that guidelines for which diagnostic procedures 
should be performed, and whether and how they are reported in published 
papers, are best determined by the scientific community through the 
pre-publication peer review process. Many studies in

[[Page 16361]]

the silica literature did not report the results of diagnostic tests. 
For example, the Vacek et al. (2009) study of lung cancer and silicosis 
mortality, which was submitted to the rulemaking record by the ACC to 
support its position, made no mention of the results of model 
diagnostic tests; rather, the authors simply stated that models were 
fitted by maximum likelihood, with the deviance used to examine model 
fitting (Document ID 2307, Attachment 6, pp. 11-12). As illustrated by 
this example, authors of epidemiological studies do not normally report 
the results of diagnostic tests; nor do such authors publish their raw 
data. Therefore, there is no data readily available to OSHA with which 
it could perform the diagnostic analysis that Dr. Cox states is 
necessary. If the suggestion is that no well-conducted epidemiological 
study that failed to report a battery of diagnostic tests or disclose 
what they showed should be relied upon for regulatory purposes, there 
would be virtually no body of scientific study left for OSHA to 
consider, raising the legal standard for issuing toxic substance 
standards far above what the Benzene decision requires. Despite this, 
OSHA maintains that, given the large number of peer-reviewed studies in 
the published scientific literature on crystalline silica, subjecting 
each model in each study to diagnostic testing along the lines 
advocated by Dr. Cox would not fundamentally change the collective 
conclusions when examining the literature base as a whole. Despite Dr. 
Cox's criticisms, the scientific literature that OSHA reviewed to draw 
its conclusions regarding material impairment of health and used in its 
quantitative risk assessment, constitutes the best available evidence 
upon which to base this toxic substance standard, in accordance with 29 
U.S.C. 655(b) and the Benzene decision and subsequent case law.
    Dr. Cox's other suggested approach to addressing model uncertainty, 
BMA, can be used to construct a risk estimate based on multiple 
exposure-response models. Unlike BMA, standard statistical practice in 
the epidemiological literature is to evaluate multiple possible models, 
identify the model that best represents the observations in the data 
set, and use this model to estimate risk. In some cases, analysts may 
report the results of two or more models, along with their respective 
fit statistics and other information to aid model selection for risk 
assessment and show the sensitivity of the results to modeling choices 
(e.g., Rice et al., 2001, Document ID 1118). These standard approaches 
were used in each of the studies relied on by OSHA in its Preliminary 
QRA.
    In contrast, BMA is a probabilistic approach designed to account 
for uncertainty inherent in the model selection process. The analyst 
begins with a set of possible models (Mi) and assigns each a 
prior probability (Pr[Mi]) that reflects the analyst's 
initial belief that model Mi represents the true exposure-
response relationship. Next, a data set is used to update the 
probabilities assigned to the models, generating the posterior 
probability for each model. Finally, the models are used in combination 
to derive a risk estimate that is a composite of the risk estimates 
from each model, weighted by each model's posterior probability (see 
Viallefont et al., 2001, Document ID 3600, Attachment 34, pp. 3216-
3217). Thus, BMA combines multiple models, and uses quantitative 
weights accounting for the analyst's belief about the plausibility of 
each model, to generate a single weighted-average risk estimate. These 
aspects of BMA are regarded by some analysts as improvements to the 
standard approaches to exposure-response modeling.
    However, Kyle Steenland, Ph.D., Professor, Department of 
Environmental Health, Rollins School of Public Health, Emory 
University, the principal author of a pooled study that OSHA heavily 
relied upon, noted that BMA is not a standard method for risk 
assessment. ``[Bayesian] model averaging, to my knowledge, has not been 
used in risk assessment ever. And so, sure, you could try that. You 
could try a million things. But I think OSHA has correctly used 
standard methods to do their risk assessment and [BMA] is not one of 
those standard methods'' (Document ID 3580, Tr. 1259).
    Indeed, BMA is a relatively new method in risk analysis. Because of 
its novelty, best practices for important steps in BMA, such as 
defining the class of models to include in the analysis, and choosing 
prior probabilities, have not been developed. Until best practices for 
BMA are established, it would be difficult for OSHA to conduct and 
properly evaluate the quality of BMA analyses. Evaluation of the 
quality of available analyses is a key step in the Agency's 
identification of the best available evidence on which to base its 
significant risk determination and benefits analysis.
    OSHA also emphasizes that, as noted by Dr. Steenland, 
scientifically accepted and standard practices were used to estimate 
risk from occupational exposure to crystalline silica (Document ID 
3580, Tr. 1259). Thus OSHA has decided that it is not necessary to use 
BMA in its QRA, and that the standard statistical methods used in the 
studies it relies upon to estimate risk are appropriate as a basis for 
risk estimation. OSHA notes that it is possible to incorporate risk 
estimates based on more than one model in its risk assessment by 
presenting ranges of risk, a strategy often used by OSHA when the best 
available evidence includes more than one model, analytical approach, 
or data set. In its Preliminary QRA, OSHA presented ranges of risks for 
silica-related lung cancer and silicosis based on different data sets 
and models, thus further lessening the utility of using more complex 
techniques such as BMA. OSHA continued this practice in its final risk 
assessment, presented in Section VI, Final Quantitative Risk Assessment 
and Significance of Risk.
2. Study Selection Bias
    Another bias described by Dr. Cox is study selection bias, which he 
stated occurs when only studies that support a positive exposure-
response relationship are included in the risk assessment, and when 
criteria for the inclusion and exclusion of studies are not clearly 
specified in advance (Document ID 2307, Attachment 4, pp. 22-23). Dr. 
Cox noted the criteria used by OSHA to select studies, as described in 
the Supplemental Literature Review of Epidemiological Studies on Lung 
Cancer Associated with Exposure to Respirable Crystalline Silica 
(Supplemental Literature Review) (Document ID 1711, Attachment 1, p. 
29). Dr. Cox, however, claimed that OSHA did not apply these criteria 
consistently, in that there may still be exposure misclassification or 
confounding present in the studies OSHA relied upon to estimate the 
risk of the health effects evaluated by the Agency (Document ID 2307, 
Attachment 4, pp. 24-25). Similarly, the American Foundry Society 
(AFS), in its post-hearing brief, asserted that, ``No formal process is 
described for search criteria or study selection'' and that OSHA's 
approach of identifying studies based upon the IARC (1997) and NIOSH 
(2002) evaluations of the literature ``is a haphazard approach that is 
not reproducible and is subject to bias. Moreover it appears to rely 
primarily on information that is more than 10 years old'' (Document ID 
4229, p. 4).
    OSHA disagrees with the arguments presented by Dr. Cox and the AFS, 
as did some commenters. The American Public Health Association (APHA), 
in its post-hearing brief, expressed strong

[[Page 16362]]

support for OSHA's study selection methods. Dr. Georges Benjamin, 
Executive Director, wrote, ``APHA recognizes that OSHA has thoroughly 
reviewed and evaluated the peer-reviewed literature on the health 
effects associated with exposure to respirable crystalline silica. 
OSHA's quantitative risk assessment is sound. The agency has relied on 
the best available evidence and acted appropriately in giving greater 
weight to those studies with the most robust designs and statistical 
analyses'' (Document ID 2178, Attachment 1, p. 1). Similarly, Dr. 
Steenland testified that ``OSHA has done a very capable job in 
conducting the summary of the literature'' (Document ID 3580, Tr. 
1235).
    In response to the criticisms by Dr. Cox and the AFS, OSHA notes 
that the silica literature was exhaustively reviewed by IARC in 1997 
and NIOSH in 2002 (Document ID 1062; 1110). As a result, there was no 
need for OSHA to initiate a new review of the historical literature. 
Instead, OSHA used the IARC and NIOSH reviews as a starting point for 
its own review. As recognized by the APHA, OSHA evaluated and 
summarized many of the studies referenced in the IARC and NIOSH 
reviews, and then performed literature searches to identify new studies 
published since the time of the IARC and NIOSH reviews. OSHA clearly 
described this process in its Review of Health Effects Literature: 
``OSHA has included in its review all published studies that the Agency 
deems relevant to assessing the hazards associated with exposure to 
respirable crystalline silica. These studies were identified from 
numerous scientific reviews that have been published previously such as 
the IARC (1997) and NIOSH (2002) evaluations of the scientific 
literature as well as from literature searches and contact with experts 
and stakeholders'' (Document ID 1711, p. 8). For its Preliminary QRA, 
OSHA relied heavily on the IARC pooled exposure-response analyses and 
risk assessment for lung cancer in 10 cohorts of silica-exposed workers 
(Steenland et al., 2001a, Document ID 0452) and multi-center study of 
silicosis mortality (Mannetje et al., 2002b, Document ID 1089). As 
stated in the Review of Health Effects Literature, these two studies 
``relied on all available cohort data from previously published 
epidemiological studies for which there were adequate quantitative data 
on worker exposures to crystalline silica to derive pooled estimates of 
disease risk'' (Document ID 1711, p. 267).
    In addition to relying on these two pooled IARC multi-center 
studies, OSHA also identified single cohort studies with sufficient 
quantitative information on exposures and disease incidence and 
mortality rates. As pointed out by Dr. Cox, OSHA described the criteria 
used for selection of the single cohort studies of lung cancer 
mortality:

    OSHA gave studies greater weight and consideration if they (1) 
included a robust number of workers; (2) had adequate length of 
follow-up; (3) had sufficient power to detect modest increases in 
lung cancer incidence and mortality; (4) used quantitative exposure 
data of sufficient quality to avoid exposure misclassification; (5) 
evaluated exposure-response relationships between exposure to silica 
and lung cancer; and (6) considered confounding factors including 
smoking and exposure to other carcinogens (Document ID 1711, 
Attachment 1, p. 29).

    Using these criteria, OSHA identified four single-cohort studies of 
lung cancer mortality that were suitable for quantitative risk 
assessment; two of these cohorts (Attfield and Costello, 2004, Document 
ID 0285; Rice et al., 2001, 1118) were included among the 10 used in 
the IARC multi-center study and two appeared later (Hughes et al., 
2001, Document ID 1060; Miller and MacCalman, 2009, 1306) (Document ID 
1711, p. 267). For NMRD mortality, in addition to the IARC multi-center 
study (Mannetje et al., 2002b, Document ID 1089), OSHA relied on Park 
et al. (2002) (Document ID 0405), who presented an exposure-response 
analysis of NMRD mortality (including silicosis and other chronic 
obstructive pulmonary diseases) among diatomaceous earth workers 
(Document ID 1711, p. 267). For silicosis morbidity, several single-
cohort studies with exposure-response analyses were selected (Chen et 
al., 2005, Document ID 0985; Hnizdo and Sluis-Cremer, 1993, 1052; 
Steenland and Brown, 1995b, 0451; Miller et al., 1998, 0374; Buchanan 
et al., 2003, 0306) (Document ID 1711, p. 267).
    With respect to Dr. Cox's claim that OSHA did not apply its 
criteria consistently, on the basis that there may still be exposure 
misclassification or confounding present, OSHA notes that it selected 
studies that best addressed the criteria; OSHA did not state that it 
only selected studies that addressed all of the criteria. Given the 
fact that some of the epidemiological studies concern exposures of 
worker populations dating back to the 1930's, there is always some 
potential for exposure misclassification or the absence of information 
on smoking. When this was the case, OSHA discussed these limitations in 
its Review of Health Effects Literature and Preliminary QRA (Document 
ID 1711). For example, OSHA discussed the lack of smoking information 
for cases and controls in the Steenland et al. (2001a, Document ID 
0452) pooled lung cancer analysis (Document ID 1711, pp. 150-151).
    With respect to the AFS's claim that OSHA relied on studies that 
were more than 10 years old, OSHA again notes that it reviewed, in its 
Review of Health Effects Literature and its Supplemental Literature 
Review, the studies in the silica literature and selected the ones that 
best met the criteria described above (Document ID 1711; 1711, 
Attachment 1). It would be improper to only select the most recent 
studies, particularly if the older studies are of higher quality based 
on the criteria. Furthermore, the studies OSHA relied upon in its 
Preliminary QRA were published between 1993 and 2009; the claim that 
OSHA primarily relied on older studies is thus misleading, when the 
studies were of relatively recent vintage and determined to be of high 
quality based on the criteria described above. The AFS also suggested 
that OSHA examine several additional foundry studies of lung cancer 
(Document ID 2379, Attachment 2, p. 24); OSHA retrieved all of these 
suggested studies, added them to the rulemaking docket following the 
informal public hearings, and discusses them in Section V.F, Comments 
and Responses Concerning Lung Cancer Mortality.
3. Data Selection Bias
    A related bias presented by Dr. Cox is data selection bias, which 
he stated occurs when only a subset of the data is used in the analysis 
``to guarantee a finding of a positive'' exposure-response relationship 
(Document ID 2307, Attachment 4, p. 26). He provided an example, the 
Attfield and Costello (2004, Document ID 0285) study of lung cancer 
mortality, which excluded data as a result of attenuation observed in 
the highest exposure group (Document ID 2307, Attachment 4, pp. 26-27). 
Attenuation of response means the exposure-response relationship 
leveled off or decreased in the highest exposure group. Referring to 
another study of the same cohort, Vacek et al. (2009, Document ID 2307, 
Attachment 6; 2011, 1486), Dr. Cox stated, ``OSHA endorses the Attfield 
and Costello findings, based on dropping cases that do not support the 
hypothesis of an ER [exposure-response] relation for lung cancer, while 
rejecting the Vacek et al. study that included more complete data (that 
was not subjected to post hoc subset selection) but that did not find a 
significant ER [exposure-response]

[[Page 16363]]

relation'' (Document ID 2307, Attachment 4, pp. 26-27).
    OSHA believes there are very valid reasons for the observance of 
attenuation of response in the highest exposure group that would 
justify the exclusion of data in Attfield and Costello (2004, Document 
ID 0285) and other studies. This issue was discussed by Gary Ginsberg, 
Ph.D., an OSHA peer reviewer from the Connecticut Department of Public 
Health, in his post-hearing comments. Dr. Ginsberg noted that several 
epidemiological studies have found an attenuation of response at higher 
doses, with possible explanations including: (1) Measurement error, 
which arises from the fact that the highest doses are associated with 
the oldest datasets, which are most prone to measurement error; (2) 
``intercurrent causes of mortality'' from high dose exposures that 
result in death to the subject prior to the completion of the long 
latency period for cancer; and (3) the healthy worker survivor effect, 
which occurs when workers with ill health leave the workforce early 
(Document ID 3574, p. 24). As discussed in Section V.F, Comments and 
Responses Concerning Lung Cancer Mortality, OSHA disagrees strongly 
with Dr. Cox's assertion that data were excluded to ensure a positive 
exposure-response relationship (Document ID 2307, Attachment 4, p. 26). 
In addition, as detailed in Section VI, Final Quantitative Risk 
Assessment and Significance of Risk, OSHA calculated quantitative risk 
estimates for lung cancer mortality from several other studies that did 
not rely on a subset of the data (Rice et al., 2001, Document ID 1118; 
Hughes et al., 2001, 1060; Miller and MacCalman, 2009, 1306; 
ToxaChemica, 2004, 0469; 1711, p. 351). These studies also demonstrated 
positive exposure-response relationships.
4. Model Selection Bias
    Another selection bias presented by Dr. Cox is model selection 
bias, which he said occurs when many different combinations of models, 
including alternative exposure metrics, different lags, alternative 
model forms, and different subsets of data, are tried with respect to 
their ``ability to produce `significant'-looking regression 
coefficients'' (Document ID 2307, Attachment 4, p. 27). This is another 
aspect of model specification error, as discussed above under model 
averaging. Dr. Cox wrote:

    This type of multiple testing of hypotheses and multiple 
comparisons of alternative approaches, followed by selection of a 
final choice based [on] the outcomes of these multiple attempts, 
completely invalidates the claimed significance levels and 
confidence intervals reported for the final ER [exposure-response] 
associations. Trying in multiple ways to find a positive 
association, and then selecting a combination that succeeds in doing 
so and reporting it as `significant,' while leaving the nominal 
(reported) statistical significance level of the final selection 
unchanged (typically at p=0.05), is a well-known recipe for 
producing false-positive associations (Document ID 2307, Attachment 
4, p. 28).

    Dr. Cox further stated that unless methods of significance level 
reduction (i.e., reducing the nominal statistical significance level of 
the final selection) are used, the study is biased towards false-
positive results (Document ID 2307, Attachment 4, p. 28).
    During the informal public hearings, counsel for the ACC asked Mr. 
Park of NIOSH's Risk Evaluation Branch about this issue, i.e., trying a 
number of modeling choices, including exposure metrics, log-
transformations, lag periods, and model subsets (Document ID 3579, Tr. 
149-150). Mr. Park's reply supports the use of multiple modeling 
choices in the risk assessment as a form of sensitivity analysis:

    Investigations like this look at a number of options. They come 
into the study not totally na[iuml]ve. They, in fact, have some very 
strong preference even before looking at the data based on prior 
knowledge. So cumulative exposure, for example, is a generally very 
high confidence choice in a metric. Trying different lags is 
interesting. It helps validate the study because you know what it 
ought to look like sort of. And in many cases, the choice does not 
make a lot of difference. So it's kind of a robust test, and 
similarly, the choice of the final model is not just coming in 
na[iuml]ve. A linear exposure response has a lot of biological 
support in many different contexts, but it could be not the best 
choice (Document ID 3579, Tr. 150-151).

    ACC counsel further asked, ``And does one at the end of this 
process, though, make any adjustment in what you consider to be the 
statistically significant relationship in light of the fact that you've 
looked at so many different models and arrangements?'' (Document ID 
3579, Tr. 151-152). Mr. Park replied, ``No, I don't think that's a 
legitimate application of a multiple comparison question'' (Document ID 
3579, Tr. 152). OSHA agrees with Mr. Park that significance level 
reduction is not appropriate in the context of testing model forms for 
risk estimation, and notes that, in the Agency's experience, 
significance level reduction is not typically performed in the 
occupational epidemiology literature. In addition, OSHA notes that, in 
many of the key studies relied upon by the Agency to estimate 
quantitative risks, the authors presented the results of multiple 
models that showed statistically significant exposure-response 
relationships. For example, Rice et al. (2001) presented the results of 
six model forms, with all except one being significant (Table 1, 
Document ID 1118, p. 41). Attfield and Costello (2004) presented the 
results of their model with and without a 15-year lag and log 
transformation, with many results being significant (Table VII, 
Document ID 0285, p. 135). Thus, OSHA concludes that model selection 
bias is not a problem in its quantitative risk assessment.
    Furthermore, OSHA disagrees with Dr. Cox's assertion that modeling 
choices are used to ``produce `significant'-looking regression 
coefficients'' (Document ID 2307, Attachment 4, p. 27). OSHA believes 
that the investigators of the studies it relied upon in its 
Preliminary, and now final, QRA made knowledgeable modeling choices 
based upon the exposure distribution and health outcome being examined. 
For example, in long-term cohort studies, such as those of lung cancer 
mortality relied upon by OSHA, most authors relied upon cumulative 
exposure (mg/m\3\-yrs or mg/m\3\-days), i.e., the concentration of 
crystalline silica exposure (mg/m\3\) multiplied by the duration of 
exposure (years or days), as an exposure metric. Consistent with 
standard statistical techniques used in epidemiology, the cumulative 
exposure metric may then be log-transformed to account for an 
asymmetric distribution with a long right tail, or attenuation, and the 
metric may be lagged by several years to account for the long latency 
period between the exposure and the development of lung cancer. When 
investigators use subsets of the data, they typically explain the 
rationale and the effect of using the subset in the analysis. These 
choices all have important justifications and are not used purely to 
produce the authors' desired results, as Dr. Cox suggested (Document ID 
2307, Attachment 4, p. 27).
5. Model Uncertainty Bias
    Related to model selection bias is Dr. Cox's assertion of model 
uncertainty bias, which he said occurs when many different models are 
examined and then one is selected on which to base risk calculations; 
this approach ``treats the finally selected model as if it were known 
to be correct, for purposes of calculating confidence intervals and 
significance levels. But, in reality, there remains great uncertainty 
about what the true causal relation between exposure and response looks 
like (if there is one)'' (Document ID 2307,

[[Page 16364]]

Attachment 4, pp. 28-29). He further stated that ignoring this bias 
leads to artificially narrow confidence intervals, which bias 
conclusions towards false-positive findings. He then cited a paper 
(Piegorsch, 2013, included in Document ID 3600) describing statistical 
methods for overcoming this bias by ``including multiple possible 
models in the calculation of results'' (Document ID 2307, Attachment 4, 
p. 29). OSHA concludes this bias is really an extension of model 
specification error and model selection bias, previously discussed, and 
maintains that best practices for model averaging have not yet been 
established, making it difficult for the Agency to conduct and properly 
evaluate the quality of BMA analyses.
6. Model Over-Fitting Bias
    Next, Dr. Cox discussed model over-fitting bias, which he said 
occurs when the same data set is used both to fit a model and to assess 
the fit; this ``leads to biased results: Estimated confidence intervals 
are too narrow (and hence lower confidence limits on estimated ER 
[exposure-response] slopes are too high); estimated significance levels 
are too small (i.e., significance is exaggerated); and estimated 
measures of goodness-of-fit overstate how well the model fits the 
data'' (Document ID 2307, Attachment 4, p. 39). He suggested using 
appropriate statistical methods, such as ``k-fold cross-validation,'' 
to overcome the bias (Document ID 2307, Attachment 4, p. 39).
    OSHA does not agree that using the same data set to fit and assess 
a model necessarily results in an over-fitting bias. The Agency 
understands over-fitting to occur when a model is excessively complex 
relative to the amount of data available such that there are a large 
number of predictors relative to the total number of observations 
available. For survival models, it is the number of events, i.e., 
deaths, that is relevant, rather than the size of the entire sample 
(Babyak, 2004, included in Document ID 3600, p. 415). If the number of 
predictors (e.g., exposure, age, gender) is small relative to the 
number of events, then there should be no bias from over-fitting. In an 
article cited and submitted to the rulemaking docket by Dr. Cox, Babyak 
(2004) discussed a simulation study that found, for survival models, an 
unacceptable bias when there were fewer than 10 to 15 events per 
independent predictor (included in Document ID 3600, p. 415). In the 
studies that OSHA relied on in its Preliminary QRA, there were 
generally a large number of events relative to the small number of 
predictors. For example, in the Miller and MacCalman (2009) study of 
British coal miners, in the lung cancer model using both quartz and 
coal dust exposures, there was a large number of events (973 lung 
cancer deaths) relative to the few predictors in the model (quartz 
exposure, coal dust exposure, cohort entry date, smoking habits at 
entry, cohort effects, and differences in regional background cause-
specific rates) (Document ID 1306, pp. 6, 9). Thus, OSHA does not agree 
the studies it relied upon were substantially influenced by over-
fitting bias. OSHA also notes that k-fold cross-validation, as 
recommended by Dr. Cox, is not typically reported in published 
occupational epidemiology studies, and that the studies the Agency 
relied upon in the Preliminary QRA were published in peer-reviewed 
journals and used statistical techniques typically used in the field of 
occupational epidemiology and epidemiology generally.
7. Residual Confounding Bias
    Dr. Cox also asserted a bias due to residual confounding by age. 
Bias due to confounding occurs in an epidemiological study, in very 
general terms, when the effect of an exposure is mixed together with 
the effect of another variable (e.g., age) not accounted for in the 
analysis. Residual confounding occurs when additional confounding 
factors are not considered, control of confounding is not precise 
enough (e.g., controlling for age by using groups with age spans that 
are too wide), or subjects are misclassified with respect to 
confounders (Document ID 3607, p. 1). Dr. Cox stated in his comments 
that:

key studies relied on by OSHA, such as Park et al. (2002), do not 
correct for biases in reported ER [exposure-response] relations due 
to residual confounding by age (within age categories), i.e., the 
fact that older workers may tend to have both higher lung cancer 
risks and higher values of occupational exposure metrics, even if 
one does not cause the other. This can induce a non-causal 
association between the occupational exposure metrics and the risk 
of cancer (Document ID 2307, Attachment 4, p. 29).

    The Park et al. (2002) study of non-malignant respiratory disease 
mortality, which Dr. Cox cited as not considering residual confounding 
by age, used 13 five-year age groups (<25, 25-29, 30-34, etc.) in the 
models (Document ID 0405, p. 37). Regarding this issue in the Park et 
al. (2002) study, in its post-hearing comments, NIOSH stated:

    This is a non-issue. The five-year categorization was used only 
for deriving the expected numbers of cases as an offset in the 
Poisson analysis using national rates which typically are classified 
in five-year intervals (on age and chronological time). The 
cumulative exposures were calculated with a 10-day resolution over 
follow-up and then averaged across observation time within 50 
cumulative exposure levels cross-classified with the five-year age-
chronological time cells of the classification table. There would be 
virtually no confounding between age and exposure [using this 
approach] (Document ID 4233, p. 33).

    OSHA agrees with this assessment, noting that it appears that age 
groups were adequately constructed to prevent residual confounding. 
OSHA thus rejects this assertion of residual confounding by age in the 
Park et al. (2002) study.
8. Summary of Biases
    In summary, OSHA received comments and heard testimony on potential 
biases in the studies upon which it relied for its QRA. The ACC's Dr. 
Cox, in particular, posited a long list of biases, including model form 
specification bias, study selection bias, data selection bias, model 
selection bias, model over-fitting bias, model uncertainty bias, 
residual confounding bias, and bias as a result of exposure measurement 
error. OSHA, in this section, has specifically addressed each of these 
types of bias (except for bias due to exposure estimation error, which 
is addressed in Section V.K, Comments and Responses Concerning Exposure 
Estimation Error and ToxaChemica's Uncertainty Analysis).
    In addition, OSHA heard testimony that countered the claims of 
biases and their potential to cause false positive results. When asked 
about the biases alleged by Dr. Cox and Dr. Long, Dr. Goldsmith 
testified, ``All of these other things, it seems to me, are smoke 
screens for an inability to want to try and see what the body of 
evidence really shows'' (Document ID 3577, Tr. 895-896). Later in his 
testimony, when asked about exposure misclassification, Dr. Goldsmith 
similarly noted, ``[a]nd for a lot of the arguments that are being put 
forward by industry, they are speculating that there is the potential 
for these biases, but they haven't gotten, [from] my perspective, the 
actual evidence that this is the case'' (Document ID 3577, Tr. 901). 
Similarly, OSHA has reviewed the record evidence extensively and is not 
aware of any specific, non-speculative evidence of biases in the 
studies that it relied upon.
    There also is a question of the extent to which Dr. Cox actually 
reviewed all of the studies that he asserted to be biased. Upon 
questioning from Anne Ryder, Attorney in the Office of the Solicitor, 
Department of Labor, Dr. Cox admitted that he had not examined the

[[Page 16365]]

issue of silica and silicosis, and that his statements about false 
positives were based on his review of the Preliminary QRA with relation 
to lung cancer only:

    MS. RYDER: . . . You talked a little bit earlier about the false 
positives that are . . . present with a lot of the studies on lung 
cancer. And, but I believe, in your comment you didn't say that 
there are any of those same false positives with studies dealing 
with silicosis and silica exposure. Is that correct?
    DR. COX: I don't think I opined on that. So--and I really 
haven't looked carefully at the question. I do take it as given that 
silica at sufficiently high and prolonged exposures causes 
silicosis. I've not really examined that literature.
    MS. RYDER: So you don't think that those studies have the same 
issues that some of the lung cancer studies have?
    DR. COX: I don't really know (Document ID 3576, Tr. 426).

    Dr. Cox further testified, regarding the likelihood that the 
conclusions of the Preliminary QRA for silicosis are correct, ``I 
expect that the evidence is much stronger for silica and silicosis. But 
I haven't reviewed it, so I can't testify to it'' (Document ID 3576, 
Tr. 427).
    OSHA believes this testimony to be inconsistent with some of the 
broad conclusions in Dr. Cox's pre-hearing written submission to the 
rulemaking record, in which he claimed that all adverse outcomes in the 
Preliminary QRA may have been affected by false positives. Dr. Cox 
concluded in this submission that:

    These multiple uncontrolled sources of false-positive bias can 
generate findings of statistically ``significant'' positive ER 
[exposure-response] associations even in random data, or in data for 
which there is no true causal relation between exposure and risk of 
adverse health responses. Because OSHA's Preliminary QRA and the 
studies on which it relies did not apply appropriate technical 
methods (which are readily available, as discussed in the 
references) to diagnose, avoid, or correct for these sources of 
false-positive conclusions, the reported findings of 
``significantly'' positive ER [exposure-response] associations 
between crystalline silica exposures at and below the current PEL 
and adverse outcomes (lung cancer, non-malignant lung disease, renal 
disease) are not different from what might be expected in the 
absence of any true ER [exposure-response] relations. They therefore 
provide no evidence for (or against) the hypothesis that a true ER 
[exposure-response] relation exists. Thus, OSHA has not established 
that a non-random association exists between crystalline silica 
exposures at or below the current PEL and the adverse health effects 
on which it bases its determination of significant risk and 
calculates supposed health effect benefits (Document ID 2307, 
Attachment 4, pp. 29-30).

    OSHA notes that ``non-malignant lung disease'' includes silicosis, 
studies of which Dr. Cox subsequently testified that he did not 
examine.
    In conclusion, the studies relied upon by OSHA for its risk 
assessment were peer-reviewed and used methods for epidemiology and 
risk assessment that are commonly used. Dr. Cox provided no study-
specific evidence (e.g., data re-analysis) to support his comments that 
the studies OSHA relied upon were adversely affected by numerous 
different types of bias. As described above, OSHA recognizes that there 
are uncertainties associated with the results of the studies relied on 
for its risk assessment, as is typically the case for epidemiological 
studies such as these. Nevertheless, as previously stated, OSHA 
maintains that it has used a body of peer-reviewed scientific 
literature that, as a whole, constitutes the best available evidence of 
the relationship between respirable crystalline silica exposure and 
silicosis, lung cancer, and the other health effects studied by the 
Agency in promulgating this final rule.

K. Comments and Responses Concerning Exposure Estimation Error and 
ToxaChemica's Uncertainty Analysis

    Exposure estimation error, a typical feature of epidemiological 
studies, occurs when the authors of an exposure-response study 
construct estimates of the study subjects' exposures using uncertain or 
incomplete exposure data. Prior to the publication of its Preliminary 
Quantitative Risk Assessment (Preliminary QRA), the Agency commissioned 
an uncertainty analysis conducted by Drs. Kyle Steenland and Scott 
Bartell, through its contractor, ToxaChemica, Inc., to address exposure 
estimation error in OSHA's risk assessment, and incorporated the 
results into the Preliminary QRA. After reviewing comments submitted to 
the record on the topic of exposure estimation error, OSHA maintains 
that it has relied upon the best available evidence by: (1) Using high-
quality exposure-response studies and modeling approaches; (2) 
performing an uncertainty analysis of the effect of exposure estimation 
error on the risk assessment results; and (3) further submitting that 
analysis to peer review. OSHA concludes from its uncertainty analysis 
that exposure estimation error did not substantially affect the results 
in the majority of studies examined (Document ID 1711, pp. 299-314).
    Furthermore, having carefully considered the public comments 
criticizing ToxaChemica's uncertainty analysis, OSHA has concluded that 
it was not necessary to conduct additional analyses to modify the 
approach adopted by Drs. Steenland and Bartell in the uncertainty 
analysis. Nor was it necessary to incorporate additional sources of 
uncertainty in the analysis. Also, given the evidence in the rulemaking 
record that these estimation errors bias results towards 
underestimating rather than overestimating the risks from exposure in 
many circumstances, it is very unlikely that regression coefficients 
and risk estimates from all of the different studies relied on in the 
Preliminary QRA were biased upward. Accordingly, OSHA remains convinced 
that the conclusions of the Agency's risk assessment are correct and 
largely unaffected by potential error in exposure measurement.
    OSHA received significant comments on the topic of exposure 
estimation error in the studies it relied on in its Review of Health 
Effects Literature and Preliminary QRA (Document ID 1711). A number of 
commenters discussed the importance of accounting for exposure 
estimation error. Dr. Cox, representing the ACC, described exposure 
estimation error as perhaps the ``most quantitatively important'' issue 
in the studies OSHA relied upon (Document ID 2307, Attachment 4, p. 
40). Similarly, Christopher M. Long, Sc.D., Principal Scientist at 
Gradient, representing the U.S. Chamber of Commerce (Chamber), 
testified that exposure measurement error is a ``common source of 
uncertainty in most occupational and environmental epidemiologic 
studies'' (Document ID 3576, Tr. 298). According to Dr. Long, this type 
of error can lead to inaccurate risk estimates by creating error in the 
exposure-response curve derived from a data set and obscuring the 
presence of a threshold (Document ID 3576, Tr. 300; see Section V.I, 
Comments and Responses Concerning Thresholds for Silica-Related 
Diseases, for further discussion on thresholds). Dr. Long further 
stated that exposure measurement error can lead to over- or under-
estimation of risk: ``the impact of exposure measurement error . . . 
can bias either high or low. It can bias towards the null. It can be a 
source of positive bias.'' (Document ID 3576, Tr. 358-359). A bias to 
the null in an exposure-response model used in a quantitative risk 
assessment is an underestimation of the relationship between exposure 
level and the rate of the disease or health effect of interest, and 
results in underestimation of risk.
    OSHA agrees with the assessments of the ACC and the Chamber with 
respect to the importance of exposure

[[Page 16366]]

measurement error. Indeed, OSHA peer reviewer, Dr. Gary Ginsberg, in 
his peer review comments (Document ID 3574, p. 21), and OSHA's risk 
assessment contractor, Dr. Steenland, in his hearing testimony 
(Document ID 3580, Tr. 1266-1267), noted the potential for exposure 
measurement error to bias exposure-response coefficients towards the 
null. Dr. Steenland explained: ``misclassification I would say in 
general tends to bias things to the null. It's harder to see positive 
exposure-response trends in the face of misclassification. It depends 
partly on the type of error. . . . But, on the whole, I would say that 
exposure measurement tends to bias things down rather than up'' 
(Document ID 3580, Tr. 1266-1267). Fewell et al., the authors of a 
paper on residual confounding submitted by the ACC, wrote, ``It is well 
recognized that under certain conditions, nondifferential measurement 
error in the exposure variable produces bias towards the null'' (2007, 
Document ID 3606, p. 646).
    Several commenters representing the ACC challenged the methods used 
in ToxaChemica's uncertainty analysis on the grounds that the analysis 
failed to adequately address exposure estimation error. In spite of 
their criticisms, critics were unable to supply better studies than 
those OSHA used. Indeed, when asked during the hearing, Dr. Long was 
unable to identify any studies that the Agency could use that 
acceptably account for the impact of exposure measurement error on 
exposure-response associations for crystalline silica (Document ID 
3576, Tr. 356-357), and none was supplied following the hearings.
    Taking into account the record evidence discussed above, OSHA 
concludes that it is possible for exposure measurement error to lead to 
either over- or under-estimation of risk and that this issue of 
exposure measurement error is not specific to the silica literature. It 
further concludes that industry representatives could not identify, and 
failed to submit, any published epidemiological studies of occupational 
disease that corrected for such bias to their satisfaction (Document ID 
3576, Tr. 356-357).
    Nevertheless, because OSHA agreed that an analysis of exposure 
estimation error as a source of uncertainty is important, it 
commissioned the uncertainty analysis discussed above to explore the 
potential effects of exposure measurement error on the conclusions of 
OSHA's risk assessment (Document ID 0469). The analysis examined the 
potential effects of exposure measurement error on the mortality risk 
estimates derived from the pooled studies of lung cancer (Steenland et 
al. 2001a, Document ID 0452) and silicosis (Mannetje 2002b, Document ID 
1089). This included the effects of estimation error on the detection 
and location of a possible threshold effect in exposure-response 
models.
    The uncertainty analysis OSHA commissioned from Drs. Steenland and 
Bartell (2004, Document ID 0469) addressed possible error in silica 
exposure estimates from: (1) Random error in individual workers' 
exposure estimates and (2) error in the conversion of dust measurements 
(typically particle count concentrations) to gravimetric respirable 
silica concentrations, which could have affected estimates of average 
exposure for job categories in the job-exposure matrices used to 
estimate workers' silica exposure. To address possible error in 
individual workers' exposure estimates, the analysts performed a Monte 
Carlo analysis, a type of simulation analysis which varies the values 
of an uncertain input to an analysis (in this case, exposure estimates) 
to explore the effects of different values on the outcome of the 
analysis. The Monte Carlo analysis sampled new values for workers' job-
specific exposure levels from distributions they believed characterized 
the exposures of individual workers in each job. In each run of the 
Monte Carlo analysis, the sampled exposure values were used to 
calculate new estimates of each worker's cumulative exposures, and the 
resulting set was used to fit a new exposure-response model.
    Similarly, the analysts performed a Monte Carlo analysis to address 
the issue of uncertainty in conversion from dust to respirable silica 
exposure, sampling new conversion factors from a normal distribution 
with means equal to the original conversion factor, calculating new 
estimates of workers' cumulative exposures, and re-fitting the 
exposure-response model for each Monte Carlo run. To examine the 
sensitivity of the model to the joint effects of both error types, the 
analysts ran 50 Monte Carlo simulations using the sampling procedure 
for both individual exposures and job-specific conversion factors. They 
also examined the effects of systematic bias in conversion factors, 
considering that these may have been consistently under-estimated or 
over-estimated for any given cohort. They addressed possible biases in 
either direction, conducting 20 simulations where the true silica 
content was assumed to be either half or double the estimated silica 
content of measured exposures.
    The results of their analysis indicated that the conclusions of the 
pooled lung cancer study conducted previously by Steenland et al. 
(Document ID 0452) and included in OSHA's Preliminary QRA were unlikely 
to be affected by the types of exposure estimation error examined by 
Drs. Steenland and Bartell, whose analysis of the underlying data was 
itself reviewed by OSHA's peer review panel. As explained below, after 
reviewing comments critical of the uncertainty analysis, OSHA reaffirms 
its conclusion that workers exposed to silica at the previous PELs are 
at significant risk of disease from their exposure.
    Drs. Long and Valberg, representing the Chamber, commented that 
Drs. Steenland and Bartell's uncertainty analysis did not address all 
potential sources of error and variability in exposure measurement, 
such as possible instrument error; possible sampling error; random 
variability in exposure levels; variability in exposure levels 
resulting from changes in worker job functions during work shifts, 
production process changes, or control system changes; variability in 
sampler type used; variability in laboratory methods for determining 
sampling results and laboratory errors; variability in duration of 
exposure sampling; variability in sampling locations; variability in 
reasons for sample data collection (e.g., compliance sampling, periodic 
sampling, random survey sampling); variability in type of samples 
collected (e.g., bulk samples, respirable dust samples); variation 
among workers and over time in the size distribution, surface area, 
recency of fracture, and other characteristics of the particles 
inhaled; and extrapolation of exposure sampling data to time periods 
for which sampling data are not available (Document ID 2330, pp. 4-5). 
OSHA notes that these sources of potential error and variability are 
common in occupational exposure estimation, and are sources of 
uncertainty in most epidemiological studies, a point with which Drs. 
Valberg and Long agree (Document ID 2330, p. 14).
    OSHA has determined that its reliance on the best available 
evidence provided it with a solid, scientifically sound foundation from 
which to conclude that exposure to crystalline silica poses a 
significant risk of harm, notwithstanding the various uncertainties 
inherent in epidemiology generally or potentially affecting any given 
study and that no studies exist entirely free from the types of data 
limitations or error and variability Drs. Valberg and Long identified. 
During the public hearing Dr. Long acknowledged

[[Page 16367]]

that OSHA had not overlooked studies that he believed adequately 
addressed the sources of error cited in his comments. He was also 
unable to provide examples of such analyses in the silica literature, 
or in any other area of occupational epidemiology (Document ID 3576, 
Tr. 355-358; see also Document ID 3577, Tr. 641, 648 (testimony of Dr. 
Kenneth Mundt)). Additionally, Drs. Valberg and Long's critique of Drs. 
Steenland and Bartell's uncertainty analysis ignores constraints on the 
available data and reasonable limits on the analysts' ability to 
investigate the full variety of possible errors and their potential 
effects on OSHA's risk assessment.
    OSHA additionally notes that Dr. Kenneth Crump, an OSHA peer 
reviewer, in his examination of ToxaChemica's (Document ID 0469) study 
of exposure uncertainty in the Steenland et al. pooled study, opined 
that it was sound. He further observed that the ``analysis of error 
conducted by [ToxaChemica] is a very strong effort. The assumptions are 
clearly described and the data upon [which] they are based appear to be 
appropriate and appropriately applied.'' Dr. Crump was careful to note, 
however, that ``there are questions, as there will always be with such 
an analysis . . . A major source of error that apparently was not 
accounted for is in assuming that the average measure of exposure 
assigned to a job is the true average'' (Document ID 3574, pp. 161-
162). Dr. Cox referenced Dr. Crump's comment in his own pre-hearing 
comments, in the context of a discussion on the importance of exposure 
uncertainty in OSHA's risk analysis (Document ID 2307, p. 40). OSHA 
addressed this particular criticism in the Review of Health Effects 
Literature and Preliminary QRA. There, it stated that it is possible 
that some job exposure estimates were above or below the true average 
for a job; however, there was no ``gold standard'' measurement 
available to appropriately test or adjust for this potential source of 
error (Document ID 1711, p. xv). The Agency further stated that the 
uncertainty, or sensitivity, analysis included potential error in job 
averages, and found that most cohorts in the lung cancer and silicosis 
mortality pooled studies were not highly sensitive to random or 
systematic error in job-average exposure estimates (Document ID 1711, 
pp. 303-314). In his final evaluation of OSHA's response to his 
comments of 2009, Dr. Crump stated, ``I believe that my comments have 
been fairly taken into account in the current draft and I have no 
further comments to make'' (Document ID 3574, p. 17).
    Similarly, Dr. Morfeld, representing the ACC, criticized Drs. 
Steenland and Bartell for performing only 50 simulations of workplace 
exposures as part of the uncertainty analysis (Document ID 2307, 
Attachment 2, p. 10). Peer reviewer Mr. Bruce Allen also remarked that 
this type of uncertainty analysis typically requires more than 50 
simulations (Document ID 3574, p. 114). However, as stated by OSHA in 
the response to peer review section of the Review of Health Effects 
Literature and Preliminary QRA (Document ID 1711, pp. 379-400), the 
results did not appear to change much with an increased number of 
simulations. Thus, OSHA has concluded that the sensitivity findings 
would not have changed substantially by running more simulations. 
Indeed, in the final peer review report conveying his evaluation of 
OSHA's response to his comments of 2009, Mr. Allen stated that OSHA 
adequately addressed his comments in the updated risk assessment 
(Document ID 3574, p. 5).
    The overall salient conclusion that OSHA draws from this peer-
reviewed analysis is that even in those cohorts where exposure error 
had some impact on exposure-response models for lung cancer or 
silicosis, the resulting risk estimates at the previous and new PELs 
remain clearly significant. Therefore, OSHA continues to rely on, and 
have confidence in, the risk analysis it had performed. In particular, 
OSHA concludes that Drs. Steenland and Bartell's modeling choices were 
based on the best available data from a variety of industrial sources 
and, through their uncertainty analysis, reached conclusions that 
survive the ACC and Chamber criticisms of the study methodology. OSHA 
further concludes that it is not necessary to conduct additional 
analysis to modify the approach adopted by Drs. Steenland and Bartell 
or to incorporate additional sources of exposure estimation uncertainty 
in the analysis.
    OSHA also disagrees with other specific criticisms that Drs. Long 
and Valberg made concerning the uncertainty analysis. Dr. Long 
testified that ``there are no formal analyses conducted to determine 
the error structures of the three sources of exposure measurement error 
included in the sensitivity analyses; for example, without any formal 
analysis, the OSHA assessment simply assumed a purely Berkson type 
error structure from the assignment of job-specific average exposure 
levels for individual exposures'' (Document ID 3576, 304-305).\9\ Dr. 
Cox expressed a similar concern that
---------------------------------------------------------------------------

    \9\ The first component of ToxaChemica's analysis takes the 
exposure level for each job in the job-exposure matrix as the mean 
exposure level for workers in that job, with error (that results 
from using the mean to estimate each individual worker's exposure) 
varying randomly around the mean (Document ID 0469, P. 10). The 
second type of error examined by ToxaChemica, resulting from the 
assignment of a single conversion factor to represent quartz 
percentage in dust samples for multiple jobs, similarly might be 
expected to vary randomly around a mean equal to the recorded 
conversion factor. Errors resulting from the assignment of job-
specific mean exposures (or conversion factors) to individual 
workers or jobs results in a type of error known as Berkson error, 
in which the true exposure level is assumed to vary randomly around 
the assigned or ``observed'' exposure level for the job (Snedecor 
and Cochran, 1989).

    OSHA has not developed an appropriate error model specifically 
for the exposure estimates in the crystalline silica studies and has 
not validated (e.g., using a validation subset) that any of the ad 
hoc error models that they discuss describes the real exposure 
estimate errors of concern. They have also provided no justification 
for ToxaChemica's assumption of a log-normal distribution without 
outliers or mixtures of different distributions . . . and have 
provided no rationale for the assumption that a=0.8*p (Document ID 
---------------------------------------------------------------------------
2307, Attachment 4, p. 45).

    OSHA disagrees with Dr. Long's and Dr. Cox's characterizations, 
which implies that Drs. Steenland and Bartell did not adequately 
investigate the patterns of error in the data available to them. As 
noted in their 2004 report and by Dr. Steenland during the public 
hearings, ToxaChemica did not have the internal validation data (true 
exposures for a subset of the data set) that would be required to 
conduct formal analyses or validation of the error structure within 
each cohort of the pooled analysis (Document ID 0469, p. 16; 3580, pp. 
1229-1231). Such data are not often available to analysts. However, 
Drs. Steenland and Bartell researched and reviewed worker exposure and 
dust composition data from several worksites to inform the error 
structures used in their analyses. For example, their analysis of 
individual workers' exposure data from the pooled analyses' industrial 
sand cohort formed the basis of the equation used for the exposure 
error simulation, which Dr. Cox represented as an assumption lacking 
any rationale. Drs. Steenland and Bartell also reviewed a number of 
studies characterizing the distribution of conversion factors across 
and within jobs at different worksites. OSHA concludes that Drs. 
Steenland and Bartell made a strong effort to collect data to inform 
their modeling choices, and that their choices were based on the

[[Page 16368]]

best available information on error structure.
    Dr. Long stated that ``another limitation of the [ToxaChemica 
uncertainty] assessment was its assumption of log-linear . . . types of 
models, including log linear models with log-transformed exposure 
variables, and it focused on cumulative measures of silica exposure 
that obscure both within-person and between-person variability in 
exposure rates'' (Document ID 3576 pp. 305-306). Dr. Long's assertion 
regarding the choice of exposure models is incorrect, as the 
sensitivity analysis was not limited to log-linear models. It included 
models with flexibility to capture nonlinearities in exposure-response, 
including spline analyses and categorical analyses, and log-
transformation of the exposure variable was used only in the lung 
cancer analysis where it was shown in the original pooled analysis to 
better fit the data and address issues of heterogeneity between cohorts 
(Document ID 0469). Drs. Steenland and Bartell found only slight 
differences between the adjusted exposure-response estimates for each 
type of model.
    Drs. Long and Valberg also contended that the cumulative exposure 
metric used in the Steenland and Bartell pooled study did not 
sufficiently allow for examination of the effects of exposure 
measurement uncertainty on the results of OSHA's risk assessment, 
because other exposure metrics could be more relevant. OSHA disagrees. 
As discussed in Section V.M, Comments and Responses Concerning Working 
Life, Life Tables, and Dose Metric, cumulative exposure is widely 
acknowledged by health experts as a driver of chronic diseases such as 
silicosis and lung cancer, has been found to fit the exposure-response 
data well in many studies of silicosis and lung cancer in the silica 
literature, and best fit the exposure-response data in the underlying 
pooled data sets to which Drs. Steenland and Bartell applied their 
subsequent uncertainty analyses. Thus, OSHA believes it was appropriate 
for this investigation of exposure estimation error to focus on the 
cumulative exposure metric, for reasons including data fit and general 
scientific understanding of this disease.
    Furthermore, Dr. Long's concern that the choice of cumulative 
silica exposure might ``obscure within-person variability in exposure 
rates'' is not well supported in the context of lung cancer and 
silicosis mortality. Because death from these diseases typically occurs 
many years after the exposure that caused it, and complete records of 
past exposures do not typically exist, it is very difficult, using any 
metric, to trace within-person exposure variability (that is, changes 
in a person's exposure over time); these factors, not the choice of 
cumulative exposure metric, make it difficult to address variability in 
individuals' exposures over time and their effects on risk. OSHA notes 
that some analysts have explored the use of other exposure metrics in 
threshold analyses, submitting studies to the record which the Agency 
has reviewed and discussed in Section V.I, Comments and Responses 
Concerning Thresholds for Silica-Related Diseases.
    Dr. Long also testified that ``[t]here's very little discussion in 
the OSHA report regarding the potential impacts of exposure measurement 
error on identification of thresholds . . . [ToxaChemica's 2004 report] 
noted that exposure-response threshold estimates are imprecise and 
appear to be highly sensitive to measurement errors'' (Document ID 3576 
p. 306). Dr. Cox further noted that exposure misclassification can 
``create the appearance of a smooth, monotonically increasing estimated 
ER [exposure-response] relation'' and shift thresholds to the left 
(Document ID 2307, Attachment 4, pp. 41-42); that is, create the 
appearance that a threshold effect occurs at a lower exposure level 
than would be seen in a data set without exposure misclassification.
    In their uncertainty analysis, Drs. Steenland and Bartell estimated 
an exposure-response threshold for the pooled cohorts in each of the 50 
runs conducted for their lung cancer analysis. They defined the 
``threshold'' as the highest cumulative exposure for which the 
estimated odds ratio was less than or equal to 1.0, reporting a mean 
value of 3.04 mg/m\3\-days and median of 33.5 mg/m\3\-days across the 
50 runs (Document ID 0469, p. 15). The authors observed that ``[t]hese 
estimates are somewhat lower than the original estimate (Steenland and 
Deddens 2002) of a threshold at 121 mg/m\3\-days (4.8 on the log 
scale), which translates to about 0.01 mg/m\3\ [10 [micro]g/m\3\] over 
a working 30-year lifetime (considering a 15-year lag), or 0.007 
[7[micro]g/m\3\] over a 45-year lifetime without considering a 15-year 
lag'' (Document ID 0469, p. 15). These exposure levels are about one-
fifth the PEL of 50 [mu]g/m\3\ included in the final standard.
    As noted by Dr. Long, the threshold estimates were highly variable 
across the 50 iterations (SD of 1.64 on the log scale), in keeping with 
other comments received by OSHA that estimates of exposure-response 
thresholds based on epidemiological data tend to be highly sensitive to 
sources of measurement error and other issues common to epidemiological 
investigations (see Section V.I, Comments and Responses Concerning 
Thresholds for Silica-Related Diseases). However, the Agency notes that 
the results of the uncertainty analysis, suggesting a possible 
cumulative exposure threshold at approximately one-fifth the final 50 
[mu]g/m3 PEL, provide no cause to doubt OSHA's determination 
that significant risk exists at both the previous and the revised PEL.
    An additional concern raised by Dr. Cox was based on his 
misunderstanding that the equation used to characterize the 
relationship between true and observed exposure in Drs. Steenland and 
Bartell's simulation, ``Exposuretrue = Exposureobserved + E'', 
concerned cumulative exposure. Dr. Cox stated that the equation is 
``inappropriate for cumulative exposures [because] both the mean and 
the variance of actual cumulative exposure received typically increase 
in direct proportion to duration'' (Document ID 2307, Attachment 4, p. 
45). That is, the longer period of time over which a cumulative 
exposure is acquired, the higher variance is likely to be, because 
cumulative exposure is the sum of the randomly varying exposures 
received on different days. However, the exposures referred to in the 
equation are the mean job-specific concentrations recorded in the job-
exposure matrix (Exposureobserved) and individuals' actual exposure 
concentrations from each job worked (Exposuretrue), not their 
cumulative exposures (Document ID 0469, p. 11). Therefore, Dr. Cox's 
criticism is unfounded.
    Dr. Cox additionally criticized the simulation analysis on the 
basis that ``[t]he usual starting point for inhalation exposures [is] 
with the random number of particles inhaled per breath modeled as a 
time-varying (non-homogenous) Poisson process . . . It is unclear why 
ToxaChemica decided to assume (and why OSHA accepted the assumption) of 
an underdispersed distribution . . . rather than assuming a Poisson 
distribution'' (Document ID 2307, Attachment 4, pp. 45-46). OSHA 
believes this criticism also reflects a misunderstanding of Drs. 
Steenland and Bartell's analysis. While it could be pertinent to an 
analysis of workers' silica dose (the amount of silica that enters the 
body), the analysis addresses the concentration of silica in the air 
near a worker's breathing zone, not internal dose. The worker's 
airborne concentration is the regulated exposure endpoint and the 
exposure of interest for OSHA's risk assessment. Thus, the uncertainty 
analysis does not need to

[[Page 16369]]

account for the number of particles inhaled per breath.
    More broadly, Dr. Cox asserted that the Monte Carlo analysis ``is 
an inappropriate tool for analyzing the effects of exposure measurement 
error on estimated exposure-response data,'' citing a paper by Gryparis 
et al. (2009) (Document ID 2307, Attachment 4, p. 44). This paper 
indicates that by randomly simulating exposure measurement error, the 
Monte Carlo approach can introduce classical error (Document ID 3870, 
p. 262). Peer reviewer Dr. Noah Seixas similarly commented that ``[t]he 
typical Monte Carlo simulation, which is what appears to have been 
done, would introduce classical error,'' that is, error which is 
independent of the unobserved variable (in this case, the true exposure 
value). He explained that, as a result, ``the estimated risks [from the 
simulation analyses] are most likely to be underestimates, or 
conservatively estimating risk. This is an important aspect of 
measurement error with significant implications for risk assessment and 
should not be overlooked.'' (Document ID 3574, pp. 116-117). Addressing 
Dr. Cox's broader point, Dr. Seixas in his peer review stated that the 
``simulation of exposure measurement error in assessing the degree of 
bias that may have been present is a reasonable approach to assessing 
this source of uncertainty'' (Document ID 3574, pp. 116). Dr. Crump 
similarly characterized the uncertainty analysis used in the Steenland 
and Bartell study as ``a strong effort'' that ``appropriately applied'' 
this method (Document ID 3574, pp. 161-162). In this regard, OSHA 
generally notes that the advantages and limitations of various methods 
to address exposure measurement error in exposure-response models is an 
area of ongoing investigation in risk assessment. As shown by the 
comments of OSHA's peer reviewers above, there is no scientific 
consensus to support Dr. Cox's opinion that the Monte Carlo analysis is 
an inappropriate approach to analyze the effects of exposure 
measurement error.
    In conclusion, through use of high quality studies and modeling, 
performance of an uncertainty analysis, and submission of the results 
of that analysis to peer review, OSHA maintains that it has relied upon 
the best available evidence. In addition, OSHA has carefully considered 
the public comments criticizing ToxaChemica's uncertainty analysis and 
has concluded that exposure estimation error did not substantially 
affect the results in the majority of studies examined (Document ID 
1711, pp. 299-314). As a result, it was not necessary to conduct 
additional analyses modifying the approach adopted by Drs. Steenland 
and Bartell. Accordingly, OSHA reaffirms its determination that the 
conclusions of the Agency's risk assessment are correct and largely 
unaffected by potential error in exposure measurement.

L. Comments and Responses Concerning Causation

    As discussed in Section V.C, Summary of the Review of Health 
Effects Literature and Preliminary QRA, OSHA finds, based upon the best 
available evidence in the published, peer-reviewed scientific 
literature, that exposure to respirable crystalline silica increases 
the risk of silicosis, lung cancer, other non-malignant respiratory 
disease (NMRD), and renal and autoimmune effects. Exposure to 
respirable crystalline silica causes silicosis and is the only known 
cause of silicosis. For other health endpoints like lung cancer that 
have both occupational and non-occupational sources of exposure, OSHA 
used a comprehensive weight-of-evidence approach to evaluate the 
published, peer-reviewed scientific studies in the literature to 
determine their overall quality and whether there is substantial 
evidence that exposure to respirable crystalline silica increases the 
risk of a particular health effect. For example, with respect to lung 
cancer, OSHA reviewed 60 epidemiological studies covering more than 30 
occupational groups in over a dozen industrial sectors and concluded 
that exposure to respirable crystalline silica increases the risk of 
lung cancer (Document ID 1711, pp. 77-170). This conclusion is 
consistent with that of the World Health Organization's International 
Agency for Research on Cancer (IARC), HHS' National Toxicology Program 
(NTP), the National Institute for Occupational Safety and Health 
(NIOSH), and many other organizations and individuals, as evidenced in 
the rulemaking record and discussed throughout this section.
    In spite of this, and in addition to asserting that OSHA's 
Preliminary QRA was affected by many biases, Dr. Cox, on behalf of the 
ACC, argued that OSHA failed to conduct statistical analyses of 
causation, which led to inaccurate conclusions about causation. He 
specifically challenged OSHA's reliance upon the IARC determination of 
carcinogenicity, as discussed in Section V.F, Comments and Responses 
Concerning Lung Cancer Mortality, and its use of the criteria for 
evaluating causality developed by the noted epidemiologist Bradford 
Hill (Document ID 2307, Attachment 4, pp. 13-14; 4027, p. 28). The Hill 
criteria are nine aspects of an association that should be considered 
when examining causation: (1) The strength of the association; (2) the 
consistency of the association; (3) the specificity of the association; 
(4) the temporal relationship of the association; (5) the biological 
gradient (i.e., dose-response curve); (6) the biological plausibility 
of the association; (7) coherency; (8) experimentation; and (9) analogy 
(Document ID 3948, pp. 295-299).
    Instead, Dr. Cox suggested that OSHA use the methods listed in 
Table 1 of his 2013 paper, ``Improving causal inferences in risk 
analysis,'' which he described as ``the most useful study designs and 
methods for valid causal analysis and modeling of causal exposure-
response (CER) relations'' (Document ID 2307, Attachment 4, p. 11). 
Because OSHA did not use these methods, Dr. Cox maintained that the 
Agency's Preliminary QRA ``asserts causal conclusions based on non-
causal studies, data, and analyses'' (Document ID 2307, Attachment 4, 
p. 3). He also contended that OSHA ``ha[d] conflated association and 
causation, ignoring the fact that modeling choices can create findings 
of statistical associations that do not predict correctly the changes 
in health effects (if any) that would be caused by changes in 
exposures'' (Document ID 2307, Attachment 4, p. 3). He claimed that 
``[t]his lapse all by itself invalidates the Preliminary QRA's 
predictions and conclusions'' (Document ID 2307, Attachment 4, p. 3). 
As discussed below, since OSHA's methodology and conclusions regarding 
causation are based on the best available evidence, they are sound. 
Consequently, Dr. Cox's contrary position is unpersuasive.
1. IARC Determination
    Dr. Cox asserted that OSHA erred in its reliance on the IARC 
determination of carcinogenicity for crystalline silica inhaled in the 
forms of quartz or cristobalite. He believed OSHA only relied on the 
IARC findings because they aligned with the Agency's opinion, noting 
that the ``IARC analysis involved some of the same researchers, same 
methodological flaws, and same gaps in explicit, well-documented 
derivations of benefits and conclusions as OSHA's own preliminary QRA'' 
(Document ID 2307, Attachment 4, pp. 13-14). OSHA, however, relied on 
IARC's determination to include lung cancer in its quantitative risk 
assessment because it constitutes the best available evidence. For this 
reason, Dr. Cox's position is without merit and OSHA's

[[Page 16370]]

findings are supported by substantial evidence in the record and 
reasonable.
    As discussed in Section V.F, Comments and Responses Concerning Lung 
Cancer Mortality, the IARC classifications and accompanying monographs 
are well recognized in the scientific community, and have been 
described by scientists as ``the most comprehensive and respected 
collection of systematically evaluated agents in the field of cancer 
epidemiology'' (Demetriou et al., 2012, Document ID 4131, p. 1273). 
IARC's conclusions resulted from a thorough expert committee review of 
the peer-reviewed scientific literature, in which crystalline silica 
dust, in the form of quartz or cristobalite, was classified as Group 1, 
``carcinogenic to humans,'' in 1997 (Document ID 2258, Attachment 8, p. 
210). Since the publication of these conclusions, the scientific 
community has reaffirmed their soundness. In March of 2009, 27 
scientists from eight countries participated in an additional IARC 
review of the scientific literature and reaffirmed that crystalline 
silica dust is a Group 1 carcinogen, i.e., ``carcinogenic to humans'' 
(Document ID 1473, p. 396). Additionally, the HHS' U.S. National 
Toxicology Program also concluded that respirable crystalline silica is 
a known human carcinogen (Document ID 1164, p. 1).
    Further supporting OSHA's reliance on IARC's determination of 
carcinogenicity for its quantitative risk assessment is testimony 
offered by scientists during the informal public hearings. This 
testimony highlighted IARC's carcinogenicity determinations as very 
thorough examinations of the scientific literature that demonstrate 
that exposure to respirable crystalline silica causes lung cancer. For 
example, when asked about Dr. Cox's causation claims during the 
informal public hearings, David Goldsmith, Ph.D., noted that causation 
was very carefully examined by IARC. He believed that IARC, in its 1997 
evaluation of evidence for cancer and silica, ``. . . chose . . . the 
best six studies that were the least confounded for inability to 
control for smoking or other kinds of hazardous exposures like 
radiation and asbestos and arsenic . . .'' (Document ID 3577, Tr. 894-
896). He also believed it ``. . . crucial . . . that we pay attention 
to those kinds of studies, that we pay attention to the kinds of 
studies that were looked at by the IARC cohort that Steenland did from 
2001. That's where they had the best evidence'' (Document ID 3577, Tr. 
894-896).
    Regarding IARC's evaluation of possible biases and confounders in 
epidemiological studies, as well as its overall determination, Frank 
Mirer, Ph.D., of CUNY School of Public Health, representing the AFL-
CIO, testified:

    IARC has active practicing scientists review--I've been on two 
IARC monographs, but not these monographs, monograph working groups. 
It's been dealt with. It's been dealt with over a week of intense 
discussion between the scientists who are on these committees, as to 
whether there's chance bias in confounding which might have led to 
these results, and by 1987 for foundries and 1997 for silica, and 
it's been decided and reaffirmed.
    So people who don't believe it are deniers, pure and simple. 
This is the scientific consensus. I was on the NTP Board of 
Scientific Counselors when we reviewed the same data. Known to be a 
human carcinogen. Once you know it's a human carcinogen from studies 
in humans, you can calculate risk rates (Document ID 3578, Tr. 937).

    That OSHA relied on the best available evidence to draw its 
conclusions was also affirmed by Dr. Cox's inability to provide 
additional studies that would have cast doubt on the Agency's causal 
analysis. Indeed, during the informal public hearings, Kenneth Crump, 
Ph.D., an OSHA peer reviewer from the Louisiana Tech University 
Foundation, asked Dr. Cox if he could identify ``any causal studies of 
silica that they [OSHA] should have used but did not use?'' Dr. Cox 
responded: ``I think OSHA could look at a paper from around 2007 of 
Brown's, on some of the issues and causal analysis, but I think the 
crystalline silica area has been behind other particulate matter areas 
. . . in not using causal analysis methods. So no, I can't point to a 
good study that they should have included but didn't'' (Document ID 
3576, Tr. 401-402). In light of the above, OSHA maintains that in 
relying on IARC's determination of carcinogenicity, its conclusions on 
causation are rooted in the best available evidence.
2. Bradford Hill Criteria and Causality
    Dr. Cox also challenged OSHA's use of Hill's criteria for 
causation. He claimed that the Bradford Hill considerations were 
neither necessary nor sufficient for establishing causation, which was 
his reason for failing to include them in the statistical methods 
listed in Table 1 of his written comments for objectively establishing 
evidence about causation (Document ID 4027, p. 28). As explained below, 
based on its review of the record, OSHA finds this position meritless, 
as it is unsupported by the best available evidence.
    As a preliminary matter, Hill's criteria for causation (Document ID 
3948) are generally accepted as a gold standard for causation in the 
scientific community. Indeed, OSHA heard testimony during the informal 
public hearings and received post-hearing comments indicating that Dr. 
Cox's assertion that statistical methods should be used to establish 
causality is not consistent with common scientific practice. For 
example, Andrew Salmon, Ph.D., an OSHA peer reviewer, wrote:

    The identification of causality as opposed to statistical 
association is, as described by Bradford Hill in his well-known 
criteria, based mainly on non-statistical considerations such as 
consistence, temporality and mechanistic plausibility: the role of 
statistics is mostly limited to establishing that there is in fact a 
quantitatively credible association to which causality may (or may 
not) be ascribed. OSHA correctly cites the substantial body of 
evidence supporting the association and causality for silicosis and 
lung cancer following silica exposure, and also quotes previous 
expert reviews (such as IARC). The causal nature of these 
associations has already been established beyond any reasonable 
doubt, and OSHA's analysis sufficiently reflects this (Document ID 
3574, p. 38).

    Similarly, Kyle Steenland, Ph.D., Professor, Department of 
Environmental Health, Rollins School of Public Health, Emory 
University, in response to a question about Dr. Cox's testimony on 
causation from Darius Sivin, Ph.D., of the UAW Health and Safety 
Department, stated that the Bradford Hill criteria are met for lung 
cancer and silicosis:

    [M]ost of the Bradford Hill criteria apply here. You know you 
can never prove causality. But when the evidence builds up to such 
an extent and you have 100 studies and they tend to be fairly 
consistent, that's when we draw a causal conclusion. And that was 
the case for cigarette smoke in lung cancer. That was the case for 
asbestos in lung cancer. And when the evidence builds up to a 
certain point, you say, yeah, it's a reasonable assumption that this 
thing causes, X causes Y (Document ID 3580, pp. 1243-1244).

    As a follow-up, OSHA asked if Dr. Steenland felt that the Bradford 
Hill criteria were met for silica health endpoints. Dr. Steenland 
replied, ``For silicosis or for lung cancer. I had said they're met for 
both'' (Document ID 3580, p. 1262).
    Gary Ginsberg, Ph.D., an OSHA peer reviewer, agreed with Dr. 
Steenland, remarking to Dr. Cox during questioning, ``I'm a little 
dumbfounded about the concern over causality, given all the animal 
evidence'' (Document ID 3576, Tr. 406). Mr. Park from NIOSH's Risk 
Evaluation Branch, in his question to Dr. Cox, echoed the sentiments of 
Dr. Ginsberg, stating:


[[Page 16371]]


    It's ludicrous to hear someone question causality. There's 100 
years of research in occupational medicine, in exposure assessment. 
People here even in industry would agree that silica they say causes 
silicosis, which causes lung cancer. There's some debate about 
whether the middle step is required. There's no question that 
there's excess lung cancer in silica-exposed populations. We look at 
literature, and we identify what we call good studies. Good studies 
are ones that look at confounding, asbestos, whatever. We make 
judgments. If there's data that allows one to control for 
confounding, that's part of the analysis. If there is confounding 
that we can't control for, we evaluate it. We ask how bad could it 
be? There's a lot of empirical judgment from people who know these 
populations, know these exposures, know these industries, who can 
make very good judgments about that. We aren't stupid. So I don't 
know where you're coming from (Document ID 3576, Tr. 410-411).

    Indeed, Kenneth Mundt, Ph.D., testifying on behalf of the 
International Diatomite Producers Association (part of the ACC 
Crystalline Silica Panel, which included Dr. Cox), and whose research 
study was the basis for the Morfeld et al. (2013, Document ID 3843) 
paper that reportedly identified a high exposure threshold for 
silicosis, also appeared to disagree with Dr. Cox's view of causation. 
Dr. Mundt testified that while he thought he could appreciate Dr. Cox's 
testimony, at some point there is sufficiently accumulated evidence of 
a causal association; he concluded, ``I think here, over time, we've 
had the advantage with the reduction of exposure to see reduction in 
disease, which I think just makes it a home run that the diseases are 
caused by, therefore can be prevented by appropriate intervention'' 
(Document ID 3577, Tr. 639-640).
    OSHA notes that Dr. Cox, upon further questioning by Mr. Park, 
appeared to concede that exposure to respirable crystalline silica 
causes silicosis; Dr. Cox stated, ``I do not question that at 
sufficiently high exposures, there are real effects'' (Document ID 
3576, Tr. 412). Later, when questioned by Anne Ryder, an attorney in 
the Solicitor of Labor's office, he made a similar statement: ``I do 
take it as given that silica at sufficiently high and prolonged 
exposures causes silicosis'' (Document ID 3576, Tr. 426). Based upon 
this testimony of Dr. Cox acknowledging that silica exposure causes 
silicosis, OSHA interprets his concern with respect to silicosis to be 
not one of causation, but rather a concern with whether there is a 
silicosis threshold (i.e., that exposure to crystalline silica must 
generally be above some level in order for silicosis to occur). Indeed, 
OSHA peer reviewer Brian Miller, Ph.D., noted in his post-hearing 
comments that Dr. Cox, when challenged, accepted that silica was causal 
for silicosis, ``but questioned whether there was evidence for 
increased risks at low concentrations; i.e. whether there was a 
threshold'' (Document ID 3574, p. 31). Thresholds for silicosis are 
addressed in great detail in Section V.I, Comments and Responses 
Concerning Thresholds for Silica-Related Diseases.
    Based on the testimony and written comments of numerous scientists 
representing both public health and industry--all of whom agree that 
causation is established by applying the Bradford Hill criteria and 
examining the totality of the evidence--OSHA strongly disagrees with 
Dr. Cox's claims that the Bradford Hill criteria are inadequate to 
evaluate causation in epidemiology and that additional statistical 
techniques are needed to establish causation. OSHA defends its reliance 
on the IARC determination of 1997 and re-determination of 2012 that 
crystalline silica is a causal agent for lung cancer. OSHA's own Review 
of Health Effects Literature further demonstrates the totality of the 
evidence supporting the causality determination (Document ID 1711). 
Indeed, other than Dr. Cox representing the ACC, no other individual or 
entity questioned causation with respect to silicosis. Even Dr. Cox's 
questioning of causation for silicosis appears to be more of a question 
about thresholds, which is discussed in Section V.I, Comments and 
Responses Concerning Thresholds for Silica-Related Diseases.
3. Dr. Cox's Proposed Statistical Methods
    OSHA reviewed the statistical methods provided by Dr. Cox in Table 
1 of his 2013 paper, ``Improving causal inferences in risk analysis,'' 
(Document ID 2307, Attachment 4, p. 11), and explains below why the 
Agency did not adopt them. For example, Intervention Time Series 
Analysis (ITSA), as proposed by Dr. Cox in his Table 1, is a method for 
assessing the impact of an intervention or shock on the trend of 
outcomes of interest (Gilmour et al., 2006, cited in Document ID 2307, 
Attachment 4, p. 11). Implementing ITSA requires time series data 
before and after the intervention for both the dependent variable 
(e.g., disease outcome) and independent variables (e.g., silica 
exposure and other predictors), as well as the point of occurrence of 
the intervention. Although time-series data are frequently available in 
epidemiological studies, for silica we do not have a specific 
``intervention point'' comparable to the implementation of a new OSHA 
standard that can be identified and analyzed. Rather, changes in 
exposure controls tend to be iterative and piecemeal, gradually 
bringing workers' exposures down over the course of a facility's 
history and affecting job-specific exposures differently at different 
points in time. Furthermore, individual workers' exposures change 
continually with new job assignments and employment. In addition, in a 
situation where the intervention really reduces the adverse outcome to 
a low level, such as 1/1000 lifetime excess risk, ITSA would require an 
enormous observational database in order to be able to estimate the 
actual post-intervention level of risk. OSHA believes the standard risk 
analysis approach of estimating an exposure-response relationship based 
on workers' exposures over time and using this model to predict the 
effects of a new standard on risk appropriately reflects the typical 
pattern of multiple and gradual changes in the workers' exposures over 
time found in most industrial facilities.
    Another method listed in Dr. Cox's Table 1, marginal structural 
models (MSM), was introduced in the late 1990s (Robins, 1998, cited in 
Document ID 2307, Attachment 4, p. 11) to address issues that can arise 
in standard modeling approaches when time-varying exposure and/or time-
dependent confounders are present.\10\ These methods are actively being 
explored in the epidemiological literature, but have not yet become a 
standard method in occupational epidemiology. As such, OSHA faces some 
of the same issues with MSM as were previously noted with BMA: 
Published, peer-reviewed studies using this approach are not available 
for the silica literature, and best practices are not yet well 
established. Thus, the incorporation of MSM in the silica risk 
assessment is not possible using the currently available literature and 
would be premature for OSHA's risk assessment generally.
---------------------------------------------------------------------------

    \10\ A time-dependent confounder is a covariate whose post-
baseline value is a risk factor for both the subsequent exposure and 
the outcome.
---------------------------------------------------------------------------

    In addition, in his post-hearing brief, Dr. Cox contended that 
``[a] well-done QRA should explicitly address the causal fraction (and 
explain the value used), rather than tacitly assuming that it is 1'' 
(Document ID 4027, p. 4). However, this claim is without grounds. OSHA 
understands Dr. Cox's reference to the ``causal fraction'' to mean 
that,

[[Page 16372]]

when estimating risk from an exposure-response model, only a fraction 
of the total estimated risk should be attributed to disease caused by 
the occupational exposure of interest. The Agency notes that the 
``causal fraction'' of risk is typically addressed through the use of 
life table analyses, which incorporate background rates for the disease 
in question. Such analyses, which OSHA used in its Preliminary QRA, 
calculate the excess risk, over and above background risk, that is 
solely attributable to the exposure in question. Thus, there is no need 
to estimate a causal fraction due to exposure. These approaches are 
further discussed in Section V.M, Comments and Responses Concerning 
Working Life, Life Tables, and Dose Metric. Furthermore, nowhere in the 
silica epidemiological literature has the use of an alternative 
``causal fraction'' approach to ascribing the causal relationship 
between silica exposure and silicosis and lung cancer been deemed 
necessary to reliably estimate risk.
4. The Assertion That the Silica Scientific Literature May Be False
    Dr. Cox also asserted that the same biases and issues with 
causation in OSHA's Quantitative Risk Assessment (QRA) were likewise 
present in the silica literature. He wrote, ``In general, the 
statistical methods and causal inferences described in this literature 
are no more credible or sound than those in OSHA's Preliminary QRA, and 
for the same reasons'' (Document ID 2307, Attachment 4, p. 30).
    The rulemaking record contains evidence that contradicts Dr. Cox's 
claims with respect to the scientific foundation of the QRA. Such 
evidence includes scientific testimony and the findings of many expert 
bodies, including IARC, the HHS National Toxicology Program, and NIOSH, 
concluding that exposure to respirable crystalline silica causes lung 
cancer. At the public hearing, Dr. Steenland, Professor at Emory 
University, testified that the body of evidence pertaining to silica 
was of equal quality to that of other occupational health hazards 
(Document ID 3580, pp. 1245-1246). Dr. Goldsmith similarly testified:

    Silica dust . . . is like asbestos and cigarette smoking in that 
exposure clearly increases the risk of many diseases. There have 
been literally thousands of research studies on exposure to 
crystalline silica in the past 30 years. Almost every study tells 
the occupational research community that workers need better 
protection to prevent severe chronic respiratory diseases, including 
lung cancer and other diseases in the future. What OSHA is proposing 
to do in revising the workplace standard for silica seems to be a 
rational response to the accumulation of published evidence 
(Document ID 3577, Tr. 865-866).

    OSHA agrees with these experts, whose positive view of the science 
supporting the need for better protection from silica exposures stands 
in contrast to Dr. Cox's claim regarding what he believes to be the 
problematic nature of the silica literature. Dr. Cox asserted in his 
written statement:

    Scientists with subject matter expertise in areas such as 
crystalline silica health effects epidemiology are not necessarily 
or usually also experts in causal analysis and valid causal 
interpretation of data, and their causal conclusions are often 
mistaken, with a pronounced bias toward declaring and publishing 
findings of `significant' effects where none actually exists (false 
positives). This has led some commentators to worry that `science is 
failing us,' due largely to widely publicized but false beliefs 
about causation (Lehrer, 2012); and that, in recent times, `Most 
published research findings are wrong' (Ioannadis, 2005), with the 
most sensational and publicized claims being most likely to be 
wrong. (Document ID 2307, Attachment 4, pp. 15-16).

    Moreover, during the public hearing, Dr. Cox stated that, with 
respect to lung cancer in the context of crystalline silica, the 
literature base may be false:

    MR. PERRY [OSHA Director of the Directorate of Standards and 
Guidance]: So as I understand it, you basically think there's a good 
possibility that the entire literature base, with respect to lung 
cancer now, I'm talking about, is wrong?
    DR. COX: You mean with respect to lung cancer in the context of 
crystalline silica?
    MR. PERRY: Yes, sir.
    DR. COX: I think that consistent with the findings of Lauer 
[Lehrer] and Ioannidis and others, I think that it's very possible 
and plausible that there is a consistent pattern of false positives 
in the literature base, yes. And that implies, yes, they are wrong. 
False positives are false (Document ID 3576, Tr. 423).

    The Ioannidis paper (Document ID 3851) used mathematical constructs 
to purportedly demonstrate that most claimed research findings are 
false, and then provided suggestions for improvement (Document ID 3851, 
p. 0696). Two of his suggestions appear particularly relevant to the 
silica literature: ``Better powered evidence, e.g., large studies or 
low-bias meta-analyses, may help, as it comes closer to the unknown 
`gold' standard. However, large studies may still have biases and these 
should be acknowledged and avoided''; and ``second, most research 
questions are addressed by many teams, and it is misleading to 
emphasize the statistically significant findings of any single team. 
What matters is the totality of the evidence'' (Document ID 3851, pp. 
0700-0701). OSHA finds no merit in the claim that most claimed research 
findings are false. Instead, it finds that the silica literature for 
lung cancer is overall trustworthy, particularly because the ``totality 
of the evidence'' characterized by large studies demonstrates a causal 
relationship between crystalline silica exposure and lung cancer, as 
IARC determined in 1997 and 2012 (Document ID 2258, Attachment 8, p. 
210; 1473, p. 396).
    OSHA likewise notes that there was disagreement on Ioannidis' 
methods and conclusions. Jonathan D. Wren of the University of 
Oklahoma, in a correspondence to the journal that published the paper, 
noted that Ioannidis, ``after all, relies heavily on other studies to 
support his premise, so if most (i.e., greater than 50%) of his cited 
studies are themselves false (including the eight of 37 that pertain to 
his own work), then his argument is automatically on shaky ground'' 
(Document ID 4087, p. 1193). In addition, Steven Goodman of Johns 
Hopkins School of Medicine and Sander Greenland of the University of 
California, Los Angeles, performed a substantive mathematical review 
(Document ID 4081) of the Ioannidis models and concluded in their 
correspondence to the same journal that ``the claims that the model 
employed in this paper constitutes `proof' that most published medical 
research claims are false, and that research in `hot' areas is most 
likely to be false, are unfounded'' (Document ID 4095, p. 0773).
    Christiana A. Demetriou, Imperial College London, et al. (2012), 
analyzed this issue of potential false positive associations in the 
field of cancer epidemiology (Document ID 4131). They examined the 
scientific literature for 509 agents classified by IARC as Group 3, 
``not classifiable as to its carcinogenicity to humans'' (Document ID 
4131). Of the 509 agents, 37 had potential false positive associations 
in the studies reviewed by IARC; this represented an overall frequency 
of potential false positive associations between 0.03 and 0.10 
(Document ID 4131). Regarding this overall false positive frequency of 
about 10 percent, the authors concluded, ``In terms of public health 
care decisions, given that the production of evidence is historical, 
public health care professionals are not expected to react immediately 
to a single positive association. Instead, they are likely to wait for 
further support or enough evidence to reach a consensus, and if a 
hypothesis is repeatedly tested, then any initial false-positive 
results will be quickly undermined'' (Document ID 4131, p. 1277). The

[[Page 16373]]

authors also cautioned that ``Reasons for criticisms that are most 
common in studies with false-positive findings can also underestimate 
an association and in terms of public health care, false-negative 
results may be a more important problem than false-positives'' 
(Document ID 4131, pp. 1278-1279). Thus, this study suggested that the 
false positive frequency in published literature is actually rather 
low, and stressed the importance of considering the totality of the 
literature, rather than a single study.
    Given these responses to Ioannidis, OSHA fundamentally rejects the 
claim that most published research findings are false. The Agency 
concludes that, most likely, where, as here, there are multiple, 
statistically significant positive findings of an association between 
silica and lung cancer made by different researchers in independent 
studies looking at distinct cohorts, the chances that there is a 
consistent pattern of false positives are small; OSHA's mandate is met 
when the weight of the evidence in the body of science constituting the 
best available evidence supports such a conclusion.

M. Comments and Responses Concerning Working Life, Life Tables, and 
Dose Metric

    As discussed in Section V.C, Summary of the Review of Health 
Effects Literature and Preliminary QRA, OSHA presented risk estimates 
associated with exposure over a working lifetime to 25, 50, 100, 250, 
and 500 [mu]g/m\3\ respirable crystalline silica (corresponding to 
cumulative exposures over 45 years to 1.125, 2.25, 4.5, 11.25, and 22.5 
mg/m\3\-yrs). For mortality from silica-related disease (i.e., lung 
cancer, silicosis and non-malignant respiratory disease (NMRD), and 
renal disease), OSHA estimated lifetime risks using a life table 
analysis that accounted for background and competing causes of death. 
The mortality risk estimates were presented as excess risk per 1,000 
workers for exposures over an 8-hour working day, 250 days per year, 
and a 45-year working lifetime. This is a legal standard that OSHA 
typically uses in health standards to satisfy the statutory mandate to 
``set the standard which most adequately assures, to the extent 
feasible, that no employee will suffer material impairment of health or 
functional capacity even if such employee has regular exposure to the 
hazard dealt with by such standard for the period of his working 
life.'' 29 U.S.C. 655(b)(5). For silicosis morbidity, OSHA based its 
risk estimates on cumulative risk models used by various investigators 
to develop quantitative exposure-response relationships. These models 
characterized the risk of developing silicosis (as detected by chest 
radiography) up to the time that cohort members (including both active 
and retired workers) were last examined. Thus, risk estimates derived 
from these studies represent less-than-lifetime risks of developing 
radiographic silicosis. OSHA did not attempt to estimate lifetime risk 
(i.e., up to age 85) for silicosis morbidity because the relationships 
between age, time, and disease onset post-exposure have not been well 
characterized.
    OSHA received critical comments from representatives of the ACC and 
the Chamber. These commenters expressed concern that (1) the working 
lifetime exposure of 45 years was not realistic for workers, (2) the 
use of life tables was improper and alternative methods should be used, 
and (3) the cumulative exposure metric does not consider the exposure 
intensity and possible resulting dose-rate effects. OSHA examines these 
comments in detail in this section, and shows why they do not alter its 
conclusion that the best available evidence in the rulemaking record 
fully supports the Agency's use of a 45-year working life in a life 
table analysis with cumulative exposure as the exposure metric of 
concern.
1. Working Life
    The Chamber commented that 45-year career silica exposures do not 
exist in today's working world, particularly in ``short term work-site 
industries'' such as construction and energy production (Document ID 
4194, p. 11; 2288, p. 11). The Chamber stated that careers in these 
jobs are closer to 6 years, pointing out that OSHA's contractor, ERG, 
estimated a 64 percent annual turnover rate in the construction 
industry. Referring to Section 6(b)(5) of the Occupational Safety and 
Health (OSH) Act of 1970, the Chamber concluded, ``OSHA improperly 
inflates risk estimates with its false 45-year policy, contradicting 
the Act, which requires standards based on actual, `working life' 
exposures--not dated hypotheticals'' (Document ID 4194, pp. 11-12; 
2288, pp. 11-12).
    As stated previously, OSHA believes that the 45-year exposure 
estimate satisfies its statutory obligation to evaluate risks from 
exposure over a working life, and notes that the Agency has 
historically based its significance-of-risk determinations on a 45-year 
working life from age 20 to age 65 in each of its substance-specific 
rulemakings conducted since 1980. The Agency's use of a 45-year working 
life in risk assessment has also been upheld by the DC Circuit (Bldg & 
Constr. Trades Dep't v. Brock, 838 F.2d 1258, 1264-65 (D.C. Cir. 1988)) 
(also see Section II, Pertinent Legal Authority). Even if most workers 
are not exposed for such a long period, some will be, and OSHA is 
legally obligated to set a standard that protects those workers to the 
extent such standard is feasible. For reasons explained throughout this 
preamble, OSHA has set the PEL for this standard at 50 [micro]g/m\3\ 
TWA. In setting the PEL, the Agency reasoned that while this level does 
not eliminate all risk from 45 years of exposures for each employee, it 
is the lowest level feasible for most operations.
    In addition, OSHA heard testimony and received several comments 
with accompanying data that support a 45-year working life in affected 
industries. For example, six worker representatives of the 
International Union of Bricklayers and Allied Craftworkers (BAC), which 
represents a portion of the unionized masonry construction industry 
(Document ID 4053, p. 2), raised their hands in the affirmative when 
asked if they had colleagues who worked for longer than 40 years in 
their trade (Document ID 3585, Tr. 3053). Following the hearings, BAC 
reviewed its International Pension Fund and counted 116 members who had 
worked in the industry for 40 years or longer. It noted that this 
figure was likely an understatement, as many workers had previous 
experience in the industry prior to being represented by BAC, and many 
BAC affiliates did not begin participation in the Fund until 
approximately a decade after its establishment in 1972 (Document ID 
4053, p. 2).
    OSHA heard similar testimony from representatives of other labor 
groups and unions. Appearing with the Laborers' Health and Safety Fund 
of North America (LHSFNA), Eddie Mallon, a long-time member of the New 
York City tunnel workers' local union, testified that he had worked in 
the tunnel business for 50 years, mainly on underground construction 
projects (Document ID 3589, Tr. 4209). Appearing with the United 
Steelworkers, Allen Harville, of the Newport News Shipbuilding Facility 
and Drydock, testified that there are workers at his shipyard with more 
than 50 years of experience. He also believed that 15 to 20 percent of 
workers had 20 to 40 years of experience (Document ID 3584, Tr. 2571).
    In addition, several union representatives appearing with the 
Building and Construction Trades Department (BCTD) of the American 
Federation of Labor and Congress of Industrial Organizations (AFL-CIO) 
also

[[Page 16374]]

commented on the working life exposure estimate. Deven Johnson, of the 
Operative Plasterers' and Cement Masons' International Association, 
testified that he thought 45 years was relevant, as many members of his 
union had received gold cards for 50 and 60 years of membership; he 
also noted that there was a 75-year member in his own local union 
(Document ID 3581, Tr. 1625-1626). Similarly, Sarah Coyne, representing 
the International Union of Painters and Allied Trades, testified that 
45 years was adequate, as ``we have many, many members who continue to 
work out in the field with the 45 years'' (Document ID 3581, Tr. 1626). 
Charles Austin, of the International Association of Sheet Metal, Air, 
Rail and Transportation Workers, added that thousands of workers in the 
union's dust screening program have been in the field for 20 to 30 
years (Document ID 3581, Tr. 1628-1629).
    In its post-hearing comment, the BCTD submitted evidence on behalf 
of the United Association of Plumbers, Fitters, Welders and HVAC 
Service Techs, which represents a portion of the workers in the 
construction industry. A review of membership records for this 
association revealed 35,649 active members with 45 years or more of 
service as a member of the union. Laurie Shadrick, Safety and Health 
National Coordinator for the United Association, indicated that this 
membership figure is considered an underestimate, as many members had 
previous work experience in the construction industry prior to joining 
the union, or were not tracked by the union after transitioning to 
other construction trades (Document ID 4073, Attachment 1b). The post-
hearing comment of the BCTD also indicated a trend of an aging 
workforce in the construction industry, with workers 65 years of age 
and older predicted to increase from 5 percent in 2012 to 8.3 percent 
in 2022 (Document ID 4073, Attachment 1a, p. 1). This age increase is 
likely due to the fact that few construction workers have a defined 
benefit pension plan, and the age for collecting Social Security 
retirement benefits has been increasing; as a result, many construction 
workers are staying employed for longer in the industry (Document ID 
4073, Attachment 1a, p. 1). Thus, the BCTD expressed its support for 
using a 45-year working life in the construction industry for risk 
assessment purposes (Document ID 4073, Attachment 1a, p. 1).
    In addition to BAC and BCTD, OSHA received post-hearing comments on 
the 45-year working life from the International Union of Operating 
Engineers (IUOE) and the American Federation of State, County and 
Municipal Employees (AFSCME). The IUOE reviewed records of the Central 
Pension Fund, in which IUOE construction and stationary local unions 
participate, and determined that the average years of service amongst 
all retirees (75,877 participants) was 21.34 years, with a maximum of 
49.93 years of active service. Of these retirees, 15,836 participants 
recorded over 30 years of service, and 1,957 participants recorded over 
40 years of service (Document ID 4025, pp. 6-7). The IUOE also pointed 
to the testimony of Anthony Bodway, Special Projects Manager at Payne & 
Dolan, Inc. and appearing with the National Asphalt Pavement 
Association (NAPA), who indicated that some workers in his company's 
milling division had been with the company anywhere from 35 to 40 years 
(Document ID 3583, Tr. 2227, 2228). Similarly, the AFSCME reported 
that, according to its 2011 poll, 49 percent of its membership had over 
10 years of experience, and 21 percent had over 20 years (Document ID 
3760, p. 2).
    The rulemaking record on this topic of the working life thus 
factually refutes the Chamber's assertion that ``no such 45-year career 
silica exposures exist in today's working world, particularly in 
construction, energy production, and other short term work-site 
industries'' (Document ID 4194, p. 11; 2288, p. 11). Instead, OSHA 
concludes that the rulemaking record demonstrates that the Agency's use 
of a 45-year working life as a basis for estimating risk is legally 
justified and factually appropriate.
2. Life Tables
    Dr. Cox, on behalf of the ACC, commented that OSHA should use 
``modern methods,'' such as Bayesian competing-risks analyses, 
expectation-maximization (EM) methods, and copula-based approaches that 
account for subdistributions and interdependencies among competing 
risks (Document ID 2307, Attachment 4, p. 61). Such methods, according 
to Dr. Cox, are needed ``[t]o obtain risk estimates . . . that have 
some resemblance to reality, and that overcome known biases in the 
na[iuml]ve life table method used by OSHA'' (Document ID 2307, 
Attachment 4, p. 61). Dr. Cox then asserted that the life table method 
used in the following studies to estimate mortality risks is also 
incorrect: Steenland et al. (2001a, Document ID 0452), Rice et al. 
(2001, Document ID 1118), and Attfield and Costello (2004, Document ID 
0285) (Document ID 2307, Attachment 4, pp. 61-63).
    OSHA does not agree that the life table method it used to estimate 
mortality risks is incorrect or inappropriate. Indeed, the Agency's 
life table approach is a standard method commonly used to estimate the 
quantitative risks of mortality. As pointed out by Rice et al. (2001), 
the life table method was developed by the National Research Council's 
BEIR IV Committee on the Biological Effects of Ionizing Radiations 
(BEIR), Board of Radiation Effects Research, in its 1988 publication on 
radon (Document ID 1118, p. 40). OSHA notes that the National Research 
Council is the operating arm of the National Academy of Sciences and 
the National Academy of Engineering, and is highly respected in the 
scientific community. As further described by Rice et al., an 
``advantage of this [actuarial] method is that it accounts for 
competing causes of death which act to remove a fraction of the 
population each year from the risk of death from lung cancer so that it 
is not necessary to assume that all workers would survive these 
competing causes to a given age'' (Document ID 1118, p. 40). Because 
this life table method is generally accepted in the scientific 
community and has been used in a variety of peer-reviewed, published 
journal articles, including some of the key studies relied upon by the 
Agency in its Preliminary QRA (e.g., Rice et al., 2001, Document ID 
1118, p. 40; Park et al., 2002, 0405, p. 38), OSHA believes it is 
appropriate here.
    Regarding the alternative methods proposed by Dr. Cox, OSHA 
believes that these methods are not widely used in the occupational 
epidemiology community. In addition, OSHA notes that Dr. Cox did not 
provide any alternate risk estimates to support the use of his proposed 
alternative methods, despite the fact that the Agency made its life 
table data available in the Review of Health Effects Literature and 
Preliminary QRA (Document ID 1711, pp. 360-378). Thus, for these 
reasons, OSHA disagrees with Dr. Cox's claim that the life table method 
used by the Agency to estimate quantitative risks was inappropriate.
3. Exposure Metric
    In its risk assessment, OSHA uses cumulative exposure, i.e., 
average exposure concentration multiplied by duration of exposure, as 
the exposure metric to quantify exposure-response relationships. It 
uses this metric because each of the key epidemiological studies on 
which the Agency relied to estimate risks used cumulative exposure as 
the exposure metric to quantify exposure-response relationships, 
although some

[[Page 16375]]

also reported significant relationships based on exposure intensity 
(Document ID 1711, p. 342). As noted in the Review of Health Effects 
Literature, the majority of studies for lung cancer and silicosis 
morbidity and mortality have consistently found significant positive 
relationships between risk and cumulative exposure (Document ID 1711, 
p. 343). For example, nine of the ten epidemiological studies included 
in the pooled analysis by Steenland et al. (2001a, Document ID 0452) 
showed positive exposure coefficients when exposure was expressed as 
cumulative exposure (Document ID 1711, p. 343).
    Commenting on this exposure metric, the ACC argued that cumulative 
exposure undervalues the role of exposure intensity, as some studies of 
silicosis have indicated a dose-rate effect, i.e., short-term exposure 
to high concentrations results in greater risk than longer-term 
exposure to lower concentrations at an equivalent cumulative exposure 
level (Document ID 4209, p. 58; 2307, Attachment A, pp. 93-94). The ACC 
added that, given that silica-related lung cancer and silicosis may 
both involve an inflammation-mediated mechanism, a dose-rate effect 
would also be expected for lung cancer (Document ID 4209, p. 58). It 
concluded that ``assessments of risk based solely on cumulative 
exposure do not account adequately for the role played by intensity of 
exposure and, accordingly, do not yield reliable estimates of risk'' 
(Document ID 4209, p. 68). Patrick Hessel, Ph.D., representing the 
Chamber, pointed to the initial comments of OSHA peer reviewer Kenneth 
Crump, Ph.D., who stated that ``[n]ot accounting for a dose-rate 
effect, if one exists, could overestimate risk at lower 
concentrations'' (Document ID 4016, p. 2, citing 1716, pp. 165-167).
    OSHA acknowledges these concerns regarding the exposure metric and 
finds them to have some merit. However, it notes that the best 
available studies use cumulative exposure as the exposure metric, as in 
common in occupational epidemiological studies. As discussed below, 
there is also substantial good evidence in the record supporting the 
use of cumulative exposure as the exposure metric for crystalline 
silica risk assessment.
    Paul Schulte, Ph.D., of NIOSH testified that ``cumulative exposure 
is a standard and appropriate metric for irreversible effects that 
occur soon after actual exposure is experienced. For lung cancer and 
nonmalignant respiratory disease, NMRD mortality, cumulative exposure 
lagged for cancer is fully justified . . . For silicosis risk 
assessment purposes, cumulative exposure is a reasonable and practical 
choice'' (Document ID 3579, Tr. 127). NIOSH also conducted a simulated 
dose rate analysis for silicosis incidence with data from a Chinese tin 
miners cohort and, in comparing exposure metrics, concluded that the 
best fit to the data was cumulative exposure with no dose-rate effect 
(Document ID 4233, pp. 36-39). This finding is consistent with the 
testimony of Dr. Steenland, who stated, ``Cumulative exposure, I might 
say, is often the best predictor of chronic disease in general, in 
epidemiology'' (Document ID 3580, Tr. 1227). OSHA also notes that using 
a cumulative exposure metric (e.g., mg/m\3\-yrs) factors in both 
exposure intensity and duration, while using only an exposure intensity 
metric (e.g., [mu]g/m\3\) ignores the influence of exposure duration. 
Dr. Crump's comment that ``[e]stimating risk based on an `incomplete' 
exposure metric like average exposure is not recommended . . . . 
[E]xposure to a particular air concentration for one week is unlikely 
to carry the same risk as exposure to that concentration for 20 years, 
although the average exposures are the same'' also supports the use of 
a cumulative exposure metric (Document ID 1716, p. 166).
    With regard to a possible dose-rate effect, OSHA agrees with Dr. 
Crump that if one exists and is unaccounted for, the result could be an 
overestimation of risks at lower concentrations (Document ID 1716, pp. 
165-167). OSHA is aware of two studies discussed in its Review of 
Health Effects Literature and Preliminary QRA that examined dose-rate 
effects on silicosis exposure-response (Document ID 1711, pp. 342-344). 
Neither study found a dose-rate effect relative to cumulative exposure 
at silica concentrations near the previous OSHA PEL (Document ID 1711, 
pp. 342-344). However, they did observe a dose-rate effect in instances 
where workers were exposed to crystalline silica concentrations far 
above the previous PEL (i.e., several-fold to orders of magnitude above 
100 [mu]g/m\3\) (Buchanan et al., 2003, Document ID 0306; Hughes et 
al., 1998, 1059). For example, the Hughes et al. (1998) study of 
diatomaceous earth workers found that the relationship between 
cumulative silica exposure and risk of silicosis was steeper for 
workers hired prior to 1950 and exposed to average concentrations above 
500 [micro]g/m\3\ compared to workers hired after 1950 and exposed to 
lower average concentrations (Document ID 1059). Similarly, the 
Buchanan et al. (2003) study of Scottish coal miners adjusted the 
cumulative exposure metric in the risk model to account for the effects 
of exposures to high concentrations where the investigators found that, 
at concentrations above 2000 [micro]g/m\3\, the risk of silicosis was 
about three times higher than the risk associated with exposure to 
lower concentrations but at the same cumulative exposure (Document ID 
0306, p. 162). OSHA concluded that there is little evidence that a 
dose-rate effect exists at concentrations in the range of the previous 
PEL (100 [micro]g/m\3\) (Document ID 1711, p. 344). However, at the 
suggestion of Dr. Crump, OSHA used the model from the Buchanan et al. 
study in its silicosis morbidity risk assessment to account for 
possible dose-rate effects at high average concentrations (Document ID 
1711, pp. 335-342). OSHA notes that the risk estimates in the exposure 
range of interest (25-500 [mu]g/m\3\) derived from the Buchanan et al. 
(2003) study were not appreciably different from those derived from the 
other studies of silicosis morbidity (see Section VI, Final 
Quantitative Risk Assessment and Significance of Risk, Table VI-1.).
    In its post-hearing brief, NIOSH also added that a ``detailed 
examination of dose rate would require extensive and real time exposure 
history which does not exist for silica (or almost any other agent)'' 
(Document ID 4233, p. 36). Similarly, Dr. Crump wrote, ``Having noted 
that there is evidence for a dose-rate effect for silicosis, it may be 
difficult to account for it quantitatively. The data are likely to be 
limited by uncertainty in exposures at earlier times, which were likely 
to be higher'' (Document ID 1716, p. 167). OSHA agrees with Dr. Crump, 
and believes that it has used the best available evidence to estimate 
risks of silicosis morbidity and sufficiently accounted for any dose-
rate effect at high silica average concentrations by using the Buchanan 
et al. (2003) study.
    For silicosis/NMRD mortality, the ACC noted that Vacek et al. 
(2009, Document ID 2307, Attachment 6) reported that, in their 
categorical analysis of the years worked at various levels of exposure 
intensity, only years worked at >200 [micro]g/m\3\ for silicosis and 
>300 [micro]g/m\3\ for NMRD were associated with increased mortality 
(Document ID 2307, Attachment A, p. 93, citing 2307, Attachment 6, pp. 
21, 23). However, OSHA believes it to be inappropriate to consider 
these results in isolation from the other study findings, and notes 
that Vacek et al. (2009) also reported statistically significant 
associations of silicosis mortality with cumulative exposure, exposure 
duration, and average exposure intensity in their

[[Page 16376]]

continuous analyses with univariate models; for NMRD mortality, there 
were statistically significant associations with cumulative exposure 
and average exposure intensity (Document ID 2307, Attachment 6, pp. 21, 
23).
    In addition, OSHA notes that Vacek et al. (2009) did not include 
both an exposure intensity term and a cumulative exposure term in the 
multivariate model, after testing for correlation between cumulative 
exposure and years at particular exposure intensity; such a model would 
indicate how exposure intensity affects any relationship with 
cumulative exposure. As Dr. Crump stated in his comments:

    To demonstrate evidence for a dose-rate effect that is not 
captured by cumulative exposure, it would be most convincing to show 
some effect of dose rate that is in addition to the effect of 
cumulative exposure. To demonstrate such an effect one would need to 
model both cumulative exposure and some effect of dose rate, and 
show that adding the effect of dose rate makes a statistically 
significant improvement to the model over that predicted by 
cumulative exposure alone (Document ID 1716, p. 166).

    Indeed, both Buchanan et al. (2003, Document ID 0306) and Hughes et 
al. (1998, Document ID 1059), when examining possible dose-rate effects 
for silicosis morbidity, specifically included both cumulative exposure 
and exposure intensity in their multivariate models. Additionally, as 
described in the lung cancer section of this preamble, the Vacek et al. 
study may be affected by both exposure misclassification and the 
healthy worker survivor effect. Both of these biases may flatten an 
exposure-response relationship, obscuring the relationship at lower 
exposure levels, which could be the reason why a significant effect was 
not found at the lower exposure levels in the Vacek et al. (2009, 
Document ID 2307, Attachment 6) multivariate analysis.
    Regarding lung cancer mortality, the ACC pointed out that Steenland 
et al. (2001a, Document ID 0452) acknowledged that duration of exposure 
did not fit the data well in their pooled lung cancer study. The ACC 
indicated that exposure intensity should be considered (Document ID 
2307, Attachment A, p. 93; 4209, p. 58, citing 0452, p. 779). OSHA 
interpreted the results of the Steenland et al. (2001, Document ID 
0452) study to simply mean that duration of exposure alone was not a 
good predictor for lung cancer mortality, where a lag period may be 
important between the exposure and the development of disease. Indeed, 
Steenland et al. found the model with logged cumulative exposure, with 
a 15-year lag, to be a strong predictor of lung cancer (Document ID 
0452, p. 779). Additionally, no new evidence of a dose-rate effect in 
lung cancer studies was submitted to the record.
    For these reasons, OSHA does not believe there to be any persuasive 
data in the record that supports a dose-rate effect at exposure 
concentrations near the revised or previous PELs. OSHA concludes that 
cumulative exposure is a reasonable exposure metric on which to base 
estimates of risk to workers exposed to crystalline silica in the 
exposure range of interest (25 to 500 [mu]g/m\3\).

N. Comments and Responses Concerning Physico-Chemical and Toxicological 
Properties of Respirable Crystalline Silica

    As discussed in the Review of Health Effects Literature and 
Preliminary Quantitative Risk Assessment (Document ID 1711, pp. 344-
350), the toxicological potency of crystalline silica is influenced by 
a number of physical and chemical factors that affect the biological 
activity of the silica particles inhaled in the lung. The toxicological 
potency of crystalline silica is largely influenced by the presence of 
oxygen free radicals on the surfaces of respirable particles; these 
chemically-reactive oxygen species interact with cellular components in 
the lung to promote and sustain the inflammatory reaction responsible 
for the lung damage associated with exposure to crystalline silica. The 
reactivity of particle surfaces is greatest when crystalline silica has 
been freshly fractured by high-energy work processes such as abrasive 
blasting, rock drilling, or sawing concrete materials. As particles age 
in the air, the surface reactivity decreases and exhibits lower 
toxicologic potency (Porter et al., 2002, Document ID 1114; Shoemaker 
et al., 1995, 0437; Vallyathan et al., 1995, 1128). In addition, 
surface impurities have been shown to alter silica toxicity. For 
example, aluminum and aluminosilicate clay on silica particles has been 
shown to decrease toxicity (Castranova et al., 1997, Document ID 0978; 
Donaldson and Borm, 1998, 1004; Fubini, 1998, 1016; Donaldson and Borm, 
1998, Document ID 1004; Fubini, 1998, 1016).
    In the preamble to the proposed standard, OSHA preliminarily 
concluded that although there is evidence that several environmental 
influences can modify surface activity to either enhance or diminish 
the toxicity of silica, the available information was insufficient to 
determine to what extent these influences may affect risk to workers in 
any particular workplace setting (Document 1711, p. 350). NIOSH 
affirmed OSHA's preliminary conclusion regarding the silica-related 
risks of exposure to clay-occluded quartz particles, which was based on 
what OSHA believed to be the best available evidence. NIOSH stated:

    NIOSH concurs with this assessment by OSHA. Currently available 
information is not adequate to inform differential quantitative risk 
management approaches for crystalline silica that are based on 
surface property measurements. Thus, NIOSH recommends a single PEL 
for respirable crystalline silica without consideration of surface 
properties (Document ID 4233, p. 44).

    Two rulemaking participants, the Brick Industry Association (BIA), 
which represents distributors and manufacturers of clay brick, and the 
Sorptive Minerals Institute (SMI), which represents many industries 
that process and mine sorptive clays for consumer products and 
commercial and industrial applications, provided comment and supporting 
evidence that the crystalline silica encountered in their workplace 
environments presents a substantially lower risk of silica-related 
disease than that reflected in the Agency's Preliminary QRA.
    BIA argued that the quartz particles found in clays and shales used 
in clay brick are occluded in aluminum-rich clay coatings. BIA 
submitted to the record several studies indicating reduced toxicity and 
fibrogenicity from exposure to quartz in aluminum-rich clays (Document 
ID 2343, Attachment 2, p. 2). It purported that ``OSHA lacks the 
statutory authority to impose the proposed rule upon the brick and 
structural clay manufacturing industry because employees in that 
industry do not face a significant risk of material impairment of 
health or functional capacity'' (Document ID 2242, pp. 2-3). BIA 
concluded that its industry should be exempted from the rule, stating: 
``OSHA should exercise its discretion to exempt the brickmaking 
industry from compliance with the proposed rule unless and until it 
determines how best to take into account the industry's low incidence 
of adverse health effects from silica toxicity'' (Document ID 2242, p. 
11).
    SMI argued that silica in sorptive clays exists as either amorphous 
silica or as geologically ancient, occluded quartz, ``neither of which 
pose the health risk identified and studied in OSHA's risk assessment'' 
(Document ID 4230, p. 2). SMI further contended that OSHA's discussion 
of aged silica ``does not accurately reflect the risk of geologically 
ancient, (occluded) silica formed millions of years ago found in

[[Page 16377]]

sorptive clays'' (Document ID 4230, p. 2). Additionally, SMI noted that 
clay products produced by the sorptive minerals industry are not heated 
to high temperatures or fractured, making them different from brick and 
pottery clays (Document ID 2377, p. 7). In support of its position, SMI 
submitted to the record several toxicity studies of silica in sorptive 
clays. It stated that the evidence does not provide the basis for a 
finding of a significant risk of material impairment of health from 
exposure to silica in sorptive clays (Document ID 4230, p. 2). 
Consequently, SMI concluded that the application of a reduced PEL and 
comprehensive standard is not warranted.
    Having considered the evidence SMI submitted to the record, OSHA 
finds that although quartz originating from bentonite deposits exhibits 
some biological activity, it is clear that it is considerably less 
toxic than unoccluded quartz. Moreover, evidence does not exist that 
would permit the Agency to evaluate the magnitude of the lifetime risk 
resulting from exposure to quartz in bentonite-containing materials and 
similar sorptive clays. This finding does not extend to the brick 
industry, where workers are exposed to silica through occluded quartz 
in aluminum rich clays. The Love et al. study (1999, Document ID 0369), 
which BIA claimed would be of useful quality for OSHA's risk 
assessment, shows sufficient cases of silicosis to demonstrate 
significant risk within the meaning used by OSHA for regulatory 
purposes. In addition, OSHA found a reduced, although still 
significant, risk of silicosis morbidity in the study of pottery 
workers (Chen et al., 2005, Document ID 0985) that BIA put forth as 
being representative of mortality in the brick industry (Document ID 
3577, Tr. 674). These findings are discussed in detail below.
1. The Clay Brick Industry
    BIA did not support a reduction in the PEL because although brick 
industry employees are exposed to crystalline silica-bearing materials, 
BIA believes silicosis is virtually non-existent in that industry. It 
contended that silica exposure in the brick industry does not cause 
similar rates of disease as in other industries because brick industry 
workers are exposed to quartz occluded in aluminum-rich layers, 
reducing the silica's toxicity. BIA concluded that ``no significant 
workplace risk for brick workers from crystalline silica exposure 
exists at the current exposure limit'' (Document ID 3577, Tr. 654) and 
that reducing the PEL would have no benefit to workers in the brick 
industry (Document ID 2300, p. 2). These concerns were also echoed by 
individual companies in the brick industry, such as Acme Brick 
(Document ID 2085, Attachment 1), Belden Brick Company (Document ID 
2378), and Riverside Brick & Supply Company, Inc. (Document ID 2346, 
Attachment 1). In addition, OSHA received over 50 letters as part of a 
letter campaign from brick industry representatives referring to BIA's 
comments on the lack of silicosis in the brick industry (e.g., Document 
ID 2004).
    The Tile Council of North America, Inc., also noted that ``[c]lay 
raw materials used in tile manufacturing are similar to those used in 
brick and sanitary ware manufacturing'' and also suggested that 
aluminosilicates decrease toxicity (Document ID 3528, p. 1). OSHA 
agrees with the Tile Council of North America, Inc., that their 
concerns mirror those of the BIA and, therefore, the Agency's 
consideration and response to BIA also applies to the tile industry.
a. Evidence on the Toxicity of Silica in Clay Brick.
    On behalf of BIA, Mr. Robert Glenn presented a series of published 
and unpublished studies (Document ID 3418), also summarized by BIA 
(Document ID 2300, Attachment 1) as evidence that ``no significant 
workplace risk for brick workers from crystalline silica exposure 
exists at the current exposure limit'' (Document ID 3577, Tr. 654). 
Most of these studies, including an unpublished report on West Virginia 
brick workers (West Virginia State Health Department, 1939), a study of 
North Carolina brick workers (Trice, 1941), a study of brick workers in 
England (Keatinge and Potter, 1949), a study of Canadian brick workers 
(Ontario Health Department, 1972), two studies of North Carolina brick 
workers (NIOSH, 1978 and NIOSH, 1980), a study of English and Scottish 
brick workers (Love et al., 1999, Document ID 0369), and an unpublished 
study commissioned by BIA of workers at 13 of its member companies 
(BIA, 2006), reported little or no silicosis among the workers examined 
(Document ID 3418; 3577, Tr. 655-669).
    Based on its review of the record evidence, OSHA finds that there 
are many silica-containing materials (e.g., other clays, sand, etc.) in 
brick and concludes that BIA's position is not supported by the best 
available evidence. The analysis contained in the studies Mr. Glenn 
presents does not meet the rigorous standards used in the studies on 
which OSHA's risk assessment relies. Indeed the studies cited by Mr. 
Glenn and BIA do not adequately support their contention that silicosis 
is ``essentially non-existent.'' Several studies were poorly designed 
and applied inappropriate procedures for evaluating chest X-rays 
(Document ID 3577, Tr. 682-685). Dr. David Weissman of NIOSH 
underscored the significance of such issues, stating: ``It's very 
important, for example, to use multiple [B] readers [to evaluate chest 
X-rays] and medians of readings, and it is very important for people to 
be blinded to how readings are done'' (Document ID 3577, Tr. 682). Also 
problematic was Mr. Glenn's failure to provide key information on the 
length of exposure or time since the first exposure in any of the 
studies he presented, which examined only currently employed workers. 
Information on duration of exposure or time since first exposure is 
essential to evaluating risk of silicosis because silicosis typically 
develops slowly and becomes detectable between 10 years and several 
decades following a worker's first exposure. In the hearing, Dr. Ken 
Rosenman also noted inadequacies related to silicosis latency, 
testifying that ``we know that silicosis occurs 20, 30 years after . . 
. first exposure . . . if people have high exposure but short duration, 
short latency, you are not going to see positive x-rays [even if 
silicosis is developing] and so it's not going to be useful'' (Document 
ID 3577, Tr. 688-689).
    Mr. Glenn acknowledged shortcomings in the studies he submitted for 
OSHA's consideration, agreeing with Dr. Weissman's points about quality 
assurance for X-ray interpretation and study design (e.g., Document ID 
3577, Tr. 683). In response to Dr. Rosenman's concerns about silicosis 
latency, he reported that no information on worker tenure or time since 
first exposure was presented in Trice (1941), Keatings and Potter 
(1949), Rajhans and Buldovsky (1972), the NIOSH studies (1978, 1980), 
or Love et al. (1999), and that more than half of the West Virginia 
brick workers studied by NIOSH (1939) had a tenure of less than 10 
years (Document ID 4021, pp. 5-6), a time period that OSHA believes is 
too short to see development of most forms of silicosis. He suggested 
that high exposures in two areas of the West Virginia facilities could 
trigger accelerated or acute silicosis, which could be observed in less 
than 10 years, if the toxicity of the silica in clay brick was 
comparable to silica found in other industries (post-hearing comments, 
p. 5). However, OSHA notes that a cross-sectional report on actively 
employed workers would not necessarily capture cases of accelerated or 
acute silicosis,

[[Page 16378]]

which are associated with severe symptoms that compromise individuals' 
ability to continue work, and therefore would result in a survivor 
effect where only unaffected workers remain at the time of study.
    Mr. Glenn further argued that the Agency should assess risk to 
brick workers based on studies from that industry because the incidence 
of silicosis among brick workers appears to be lower than among workers 
in other industries (Document ID 3577, Tr. 670). For the reasons 
discussed above, OSHA does not believe the studies submitted by Mr. 
Glenn provide an adequate basis for risk assessment. In addition, 
studies presented did not: (1) Include retired workers; (2) report the 
duration of workers' exposure to silica; (3) employ, in most cases, 
quality-assurance practices for interpreting workers' medical exams; or 
(4) include estimates of workers' silica exposures. Furthermore, Mr. 
Glenn acknowledged in the informal public hearing that the Love et al. 
(1999, Document ID 0369) study of 1,925 workers employed at brick 
plants in England and Scotland in 1990-1991 is the only available study 
of brick workers that presented exposure-response information (Document 
ID 3577, Tr. 692). He characterized the results of that study as 
contradictory to OSHA's risk assessment for silicosis morbidity because 
the authors concluded that frequency of pneumoconiosis is low in 
comparison to other quartz-exposed workers (Document ID 4021, p. 2). He 
also cited an analysis by Miller and Soutar (Document ID 1098) (Dr. 
Soutar is a co-author of the Love et al. study) that compared silicosis 
risk estimates derived from Love et al. and those from Buchanan et 
al.'s study of Scottish coal workers exposed to silica, and concluded 
that silicosis risk among the coal workers far exceeded that among 
brick workers (Document ID 3577, Tr. 671). He furthermore concluded 
that the Love et al. study is ``the only sensible study to be used for 
setting an exposure limit for quartz in brick manufacturing.'' 
(Document ID 3577, Tr. 679).
    Based on review of the Love et al. study (Document ID 0369), OSHA 
agrees with Mr. Glenn's claim that the silicosis risk among workers in 
clay brick industries appears to be somewhat lower than might be 
expected in other industries. However, OSHA is unconvinced by Mr. 
Glenn's argument that risk to workers exposed at the previous PEL is 
not significant because the cases of silicosis reported in this study 
are sufficient to show significant risk within the meaning used by OSHA 
for regulatory purposes (1 in 1,000 workers exposed for a working 
lifetime).
    Love et al. reported that 3.7 percent of workers with radiographs 
were classified as ILO Category 0/1 (any signs of small opacities) and 
1.4 percent of workers were classified as ILO Category 1/0 (small 
radiographic opacities) or greater. Furthermore, among workers aged 55 
and older, the age category most likely to have had sufficient time 
since first exposure to develop detectable lung abnormalities from 
silicosis exposure, Love et al. reported prevalences of abnormal 
radiographs ranging from 2.9 percent (cumulative exposure below 0.5 mg/
yr-m\3\) to 16.4 percent (exposure at least 4 mg/yr-m\3\) (Love et al. 
1999, Document ID 0369, Table 4, p. 129). According to the study 
authors, these abnormalities ``are the most likely dust related 
pathology--namely, silicosis'' (Document ID 0369, p. 132). Given that 
OSHA considers a lifetime risk of 0.1 percent (1 in 1,000) to clearly 
represent a significant risk, OSHA considers the Love et al. study to 
have demonstrated a significant risk to brick workers even if only a 
tiny fraction of the abnormalities observed in the study population 
represent developing silicosis (see Benzene, 448 U.S. 607, 655 n. 2). 
According to the study authors, ``the estimated exposure-response 
relation for quartz suggests considerable risks of radiological 
abnormality even at concentrations of 0.1 mg/m\3\ [100 [mu]g/m\3\] of 
quartz'' (Document ID 0369, p. 132).
    OSHA concludes that, despite the possibly lower toxicity of silica 
in the clay brick industry compared to other forms, and despite the 
Love et al. study's likely underestimation of risk due to exclusion of 
retired workers, the study demonstrates significant risk among brick 
workers exposed at the previous general industry PEL. It also suggests 
that the silicosis risk among brick workers would remain significant 
even at the new PEL. Furthermore, OSHA is unconvinced by Mr. Glenn's 
argument that the Agency should develop a quantitative risk assessment 
based on the Love et al. study, because that study excluded retired 
workers and had inadequate worker follow-up. As explained earlier in 
this section, adequate follow-up time and inclusion of retired workers 
is extremely important to allow for latency in the development of 
silicosis. Therefore, OSHA relied on studies including retired workers 
in its QRA for silicosis morbidity.
    Mr. Glenn additionally argued that the risk of lung cancer from 
silica exposure among brick workers is likely to be lower than among 
workers exposed to silica in other work settings. Mr. Glenn 
acknowledged that ``there are no published mortality studies of brick 
workers that look at cause of death or lung cancer death'' (Document ID 
3577, Tr. 674). However, he stated that ``pottery clays are similar to 
the structural clays used in brickmaking in that the quartz is occluded 
in aluminum-rich layers of bentonite, kaolinite, and illite,'' and that 
OSHA should consider studies of mortality among pottery workers as 
representative of the brick industry (Tr. 674). Mr. Glenn cited the 
Chen et al. (2005) study of Chinese pottery workers, which reported a 
weak exposure-response relationship between silica exposure and lung 
cancer mortality, and which appeared to be affected by PAH-related 
confounding. He concluded that the Chen et al. study ``provides strong 
evidence for aluminum-rich clays suppressing any potential 
carcinogenesis from quartz'' (Document ID 3577, Tr. 675).
    OSHA acknowledges that occlusion may weaken the carcinogenicity of 
silica in the brick clay industry, but does not believe that the Chen 
et al. study provides conclusive evidence of such an effect. This is 
because of the relatively low carcinogenic potential of silica and the 
difficulty involved in interpreting one cohort with known issues of 
confounding (see Section V.F, Comments and Responses Concerning Lung 
Cancer Mortality). OSHA also notes, however, that it estimated risks of 
silicosis morbidity from the cited Chen et al. (2005, Document ID 0985) 
study, and found the risk among pottery workers to be significant, with 
60 deaths per 1,000 workers at the previous PEL of 100 [mu]g/
m3 and 20 deaths per 1,000 workers at the revised PEL of 50 
[mu]g/m3 (as indicated in Section VI, Final Quantitative 
Risk Assessment and Significance of Risk, Table VI-1). Thus, given Mr. 
Glenn's assertion that pottery clays are similar to the clays used in 
brickmaking, OSHA believes that while the risk of silicosis morbidity 
may be lower than that seen in other industry sectors, it is likely to 
still be significant in the brickmaking industry.
    Thus, OSHA concludes that the BIA's position is not supported by 
the best available evidence. The studies cited by Mr. Glenn to support 
his contention that brick workers are not at significant risk of 
silica-related disease do not have the same standards as those studies 
used by OSHA in its quantitative risk assessment. Furthermore, in the 
highest-quality study brought forward by Mr. Glenn (Love et al. 1999, 
Document ID 0369), there are sufficient cases of silicosis to 
demonstrate significant risk within the meaning used by OSHA for

[[Page 16379]]

regulatory purposes. Even if the commenters' arguments that silica in 
clay brick is less toxic were, to some extent, legitimate, this would 
not significantly affect OSHA's own estimates from the epidemiological 
evidence of the risks of silicosis.
2. Sorptive Minerals (Bentonite Clay) Processing
    SMI asserted that the physico-chemical form of respirable 
crystalline silica in sorptive clays reduces the toxicologic potency of 
crystalline silica relative to the forms of silica common to most 
studies relied on in OSHA's Preliminary QRA. In other words, the risk 
associated with exposure to silica in sorptive clays is assertedly 
lower than the risk associated with exposure to silica in other 
materials. SMI based this view on what it deemed the ``best available 
scientific literature,'' epidemiological, in vitro, and animal evidence 
OSHA had not previously considered. It believed the evidence showed 
reduced risk from exposure to occluded quartz found in the sorptive 
clays and that occluded quartz does not create a risk similar to that 
posed by freshly fractured quartz (Document ID 2377, p. 7). Based on 
this, SMI contended that the results of OSHA's Preliminary QRA were not 
applicable to the sorptive minerals industry, and a more stringent 
standard for crystalline silica is ``neither warranted nor legally 
permissible'' (Document ID 4230, p. 1). As discussed below, OSHA 
reviewed the evidence submitted by SMI and finds that although the 
studies provide evidence of some biological activity in quartz 
originating from bentonite deposits, there is not quantitative evidence 
that would permit the Agency to evaluate the magnitude of the lifetime 
risk resulting from exposure to quartz in bentonite-containing 
materials and similar sorptive clays.
a. Evidence on the Toxicity of Silica in Sorptive Minerals
    SMI submitted a number of studies to the rulemaking record. First, 
it summarized a retrospective study by Waxweiler et al. (Document ID 
3998, Attachment 18e) of attapulgite clay workers in Georgia in which 
the authors concluded that there was a significant deficit of non-
malignant respiratory disease mortality and no clear excess of lung 
cancer mortality among these workers. It used the study as the basis 
for its recommendation to OSHA that the study ``be cited and that 
exposures in the industry be recognized in the final rule as not posing 
the same hazard as those in industries with reactive crystalline 
silica'' (Document ID 2377, p. 10).
    Based on its review of the rulemaking record, OSHA concludes that 
the Waxweiler et al. study is of limited value for assessing the hazard 
potential of quartz in bentonite clay because of the low airborne 
levels of silica to which the workers were exposed. The Agency's 
conclusion is supported by NIOSH's summary of the time-weighted average 
(TWA) exposures calculated for each job category in Waxweiler et al. 
(1988, Document ID 3998, Attachment 18e), which were found to be 
``within the acceptable limits as recommended by NIOSH (i.e., <0.05 mg/
m3 [50 [mu]g/m3]) . . . and most were 
substantially lower'' (Document ID 4233, p. 41). It cannot be known to 
what extent the low toxicity of the dust or the low exposures 
experienced by the workers each contributed to the lack of observed 
disease.
    SMI also presented a World Health Organization (WHO) document 
(2005, Document ID 3929), which recognized that ``studies of workers 
exposed to sorptive clays have not identified significant silicosis 
risk'' (Document ID 2377, p. 10). However, although WHO did find that 
there were no reported cases of fibrotic reaction in humans exposed to 
montmorillonite minerals in the absence of crystalline silica (Document 
ID 3929, p. 130), the WHO report does discuss the long-term effects 
from exposure to crystalline silica, including silicosis and lung 
cancer. In fact, with respect to evaluating the hazards associated with 
exposure to bentonite clay, WHO regarded silica as a potential 
confounder (Document ID 3929, p. 136). Thus, WHO did not specifically 
make any findings with respect to the hazard potential of quartz in the 
bentonite clay mineral matrix but instead recognized the hazard 
presented by exposure to crystalline silica generally.
    Additionally, the WHO (Document ID 3929, pp. 114, 118) cited two 
case/case series reports of bentonite-exposed workers, one 
demonstrating increasing prevalence of silicosis with increasing 
exposure to bentonite dust (Rombola and Guardascione, 1955, Document ID 
3998, Attachment 18) and another describing cases of silicosis among 
workers exposed to bentonite dust (Phibbs et al. 1971, Document ID 
3998, Attachment 18b). Rombola and Guardascione (1955) found silicosis 
prevalences of 35.5 and 12.8 percent in two bentonite processing 
factories, and 6 percent in a bentonite mine. In the factory where the 
highest exposures occurred, 10 of the 26 cases found were severe and 
all cases developed with seven or fewer years of exposure, indicating 
that exposure levels were extremely high (Document ID 4233, p. 42, 
citing 3998, Attachment 18). Phibbs et al. (1971) reviewed chest x-rays 
of 32 workers in two bentonite plants, of which x-ray films for 14 
indicated silicosis ranging from minimal to advanced. Although the 
exposure of affected workers to respirable dust or quartz is not known, 
industrial hygiene surveys conducted in four bentonite plants showed 
some areas having particle counts in excess of 3 to 11 times the ACGIH 
particle count limit (Document ID 3998, Attachment 18b, p. 4). This is 
roughly equivalent to exposure levels between 8 and 28 times OSHA's 
former general industry PEL of 100 [mu]g/m3 (given that the 
particle count limit is about 2.5 or more times higher than the 
gravimetric limit for respirable quartz (see Section V.C, Summary of 
the Review of Health Effects Literature and Preliminary QRA). Exposures 
of this magnitude are considerably higher than those experienced by 
worker cohorts of the studies relied on by OSHA in its Final Risk 
Assessment and discussed in Section V.C, Summary of the Review of 
Health Effects Literature and Preliminary QRA. For example, the median 
of average exposures reported in the ten cohort studies used by 
Steenland et al. (2001, Document ID 0684, p. 775) ranged from about 
one-half to six times the former general industry PEL.
    The lack of specific exposure information on bentonite workers 
found with silicosis, combined with the extraordinary exposures 
experienced by workers in the bentonite plants studied by Phibbs et al. 
(1971), make this study, while concerning, unsuitable for evaluating 
risks in the range of the former and final rule PELs. OSHA notes that 
the WHO report also concluded that available data were inadequate to 
conclusively establish a dose-response relationship or even a cause-
and-effect relationship for bentonite dust, and that its role in 
inducing pneumoconiosis remains uncertain.
    SMI also presented evidence from animal and in vitro studies that 
it believes shows that respirable crystalline quartz present in 
sorptive clays exists in a distinct occluded form, which significantly 
mitigates adverse health effects due to the physico-chemical 
characteristics of the occluded quartz. As discussed below, based on 
careful review of the studies SMI cited, OSHA believes these studies 
indicate that silica in bentonite clay is of lower toxicologic potency 
than that found in other industry sectors.
    SMI submitted two studies: an animal study (Creutzenberg et al. 
2008,

[[Page 16380]]

Document ID 3891) and a study of the characteristics of quartz samples 
isolated from bentonite (Miles et al. 2008, Document ID 4173). SMI 
contended that these studies demonstrate the low toxicity potential of 
geologically ancient occluded quartz found in sorptive clays (Document 
ID 2377, pp. 8-9).
    Creutzenberg et al. (2008) summarized the findings from a rat study 
aimed at ``characterizing the differences in biological activity 
between crystalline ground reference quartz (DQ12) and a quartz with 
occluded surfaces (quartz isolate) obtained from a clay deposit formed 
110-112 million years ago'' (Document ID 3891, p. 995). Based on 
histopathological assessment of the lungs in each treatment group, 
Creutzenberg et al. (2008, Document ID 3891) found that the DQ12 
reference quartz group exhibited a significantly stronger inflammatory 
reaction than the quartz isolate, which showed a slight but still 
statistically significant inflammatory response compared to the control 
group. The increased inflammatory response was observed at day 3 but 
not at 28 or 90 days. Thus, reaction elicited by the quartz isolate, 
thought to have similar properties to bentonite, was considered by the 
investigators to represent a moderate effect that did not progress. In 
light of this, the implications of this study for development of 
silicosis are unclear.
    SMI also cited Miles et al. (2008, Document ID 4173), who studied 
the mineralogical and chemical characteristics of quartz samples 
isolated from bentonite, including the quartz isolate used by 
Creutzenberg et al. (2008) in their animal study. Their evaluation 
identified several differences in the chemical and physical properties 
of the quartz isolates and unoccluded quartz that could help explain 
the observed differences in toxicity (Document ID 4173); these included 
differences in crystal structure, electrical potential of particle 
surfaces, and, possibly, differences in the reactivity of surface-free 
radicals owing to the presence of iron ions in the residual clay 
material associated with the quartz isolates.
    With respect to the two studies just discussed, animal evidence 
cited by SMI demonstrates that quartz in bentonite induces a modest 
inflammatory reaction in the lung that does not persist (Creutzenberg 
et al., 2008, Document ID 3891). Such a reaction is notably different 
from the persistent and stronger response seen with standard 
experimental quartz material without surface occlusion (Creutzenberg et 
al., 2008, Document ID 3891). Physical and chemical characteristics of 
quartz from bentonite deposits have been shown to differ from standard 
experimental quartz in ways that can explain its reduced toxicity 
(Miles et al., 2008, Document ID 4173). However, the animal studies 
cited by SMI are not suitable for risk assessment since they were 
short-term (90 days), single-dose experiments.
    In sum, human evidence on the toxicity of quartz in bentonite clay 
includes one study cited by SMI that did not find an excess risk of 
respiratory disease (Waxweiller et al., Document ID 3998, Attachment 
18e). However, because exposures experienced by the workers were low 
with most less than that of the final rule PEL, the lack of an observed 
effect cannot be solely attributed to the nature of the quartz 
particles. Two studies of bentonite workers found a high prevalence of 
silicosis based on x-ray findings (Rombola and Guardascione, 1955, 
Document ID 3998, Attachment 18; Phibbs et al., 1971, Document ID 3998, 
Attachment 18b). Limited exposure data provided in the studies as well 
as the relatively short latencies seen among cases of severe silicosis 
make it clear that the bentonite workers were exposed to extremely high 
dust levels. Neither of these studies can be relied on to evaluate 
disease risk in the exposure range of the former and revised respirable 
crystalline silica PELs.
    OSHA finds that the evidence for quartz originating from bentonite 
deposits indicates some biological activity, but also indicates lower 
toxicity than standard experimental quartz (which has similar 
characteristics to quartz encountered in most workplaces where 
exposures occur). For regulatory purposes, however, OSHA finds that the 
evidence does not exist that would permit the Agency to evaluate the 
magnitude of the lifetime risk resulting from exposure to quartz in 
sorptive clays at the 100 [mu]g/m\3\ PEL. Instead, OSHA finds that the 
record provides no sound basis for determining the significance of risk 
for exposure to sorptive clays containing respirable quartz. Thus, OSHA 
is excluding sorptive clays (as described specifically in the Scope 
part of Section XV, Summary and Explanation) from the scope of the 
rule, until such time that sufficient science has been developed to 
permit evaluation of the significance of the risk. However, in 
excluding sorptive clays from the rule, the general industry PEL, as 
described in 29 CFR 1910.1000 Table Z-3, will continue to apply.

VI. Final Quantitative Risk Assessment and Significance of Risk

A. Introduction

    To promulgate a standard that regulates workplace exposure to toxic 
materials or harmful physical agents, OSHA must first determine that 
the standard reduces a ``significant risk'' of ``material impairment.'' 
Section 6(b)(5) of the OSH Act, 29 U.S.C. 655(b). The first part of 
this requirement, ``significant risk,'' refers to the likelihood of 
harm, whereas the second part, ``material impairment,'' refers to the 
severity of the consequences of exposure. Section II, Pertinent Legal 
Authority, of this preamble addresses the statutory bases for these 
requirements and how they have been construed by the Supreme Court and 
federal courts of appeals.
    It is the Agency's practice to estimate risk to workers by using 
quantitative risk assessment and determining the significance of that 
risk based on the best available evidence. Using that evidence, OSHA 
identifies material health impairments associated with potentially 
hazardous occupational exposures, and, when possible, provides a 
quantitative assessment of exposed workers' risk of these impairments. 
The Agency then evaluates whether these risks are severe enough to 
warrant regulatory action and determines whether a new or revised rule 
will substantially reduce these risks. For single-substance standards 
governed by section 6(b)(5) of the OSH Act, 29 U.S.C. 655(b)(5), OSHA 
sets a permissible exposure limit (PEL) based on that risk assessment 
as well as feasibility considerations. These health and risk 
determinations are made in the context of a rulemaking record in which 
the body of evidence used to establish material impairment, assess 
risks, and identify affected worker population, as well as the Agency's 
preliminary risk assessment, are placed in a public rulemaking record 
and subject to public comment. Final determinations regarding the 
standard, including final determinations of material impairment and 
risk, are thus based on consideration of the entire rulemaking record.
    In this case, OSHA reviewed extensive toxicological, 
epidemiological, and experimental research pertaining to the adverse 
health effects of occupational exposure to respirable crystalline 
silica, including silicosis, other non-malignant respiratory disease 
(NMRD), lung cancer, and autoimmune and renal diseases. Using the 
information collected during this review, the Agency

[[Page 16381]]

developed quantitative estimates of the excess risk of mortality and 
morbidity attributable to the previously allowed and revised respirable 
crystalline silica PELs; these estimates were published with the 
proposed rule. The Agency subsequently reexamined these estimates in 
light of the rulemaking record as a whole, including comments, 
testimony, data, and other information, and has determined that long-
term exposure at and above the previous PELs would pose a significant 
risk to workers' health, and that adoption of the new PEL and other 
provisions of the final rule will substantially reduce this risk. Based 
on these findings, the Agency is adopting a new PEL of 50 [mu]g/m\3\.
    Even though OSHA's risk assessment indicates that a significant 
risk also exists at the revised action level of 25 [mu]g/m\3\, the 
Agency is not adopting a PEL below the revised 50 [mu]g/m\3\ limit 
because OSHA must also consider the technological and economic 
feasibility of the standard in determining exposure limits. As 
explained in the Summary and Explanation for paragraph (c), Permissible 
Exposure Limit (PEL), of the general industry/maritime standard 
(paragraph (d) for construction), OSHA has determined that, with the 
adoption of additional engineering and work practice controls, the 
revised PEL of 50 [mu]g/m\3\ is technologically and economically 
feasible in most operations in the affected general industrial and 
maritime sectors and in the construction industry, but that a lower PEL 
of 25 [mu]g/m\3\ is not technologically feasible for most of these 
operations (see Section VII, Summary of the Final Economic Analysis and 
Final Regulatory Flexibility Analysis (FEA) and Chapter IV, 
Technological Feasibility, of the FEA). Therefore, OSHA concludes that 
by establishing the 50 [mu]g/m\3\ PEL, the Agency has reduced 
significant risk to the extent feasible.

B. OSHA's Findings of Material Impairments of Health

    As discussed below and in OSHA's Review of Health Effects 
Literature and Preliminary QRA (Document ID 1711, pp. 7-229), there is 
convincing evidence that inhalation exposure to respirable crystalline 
silica increases the risk of a variety of adverse health effects, 
including silicosis, NMRD (such as chronic bronchitis and emphysema), 
lung cancer, kidney disease, immunological effects, and infectious 
tuberculosis (TB). OSHA considers each of these conditions to be a 
material impairment of health. These diseases make it difficult or 
impossible to work and result in significant and permanent functional 
limitations, reduced quality of life, and sometimes death. When these 
diseases coexist, as is common, the effects are particularly 
debilitating (Rice and Stayner, 1995, Document ID 0418; Rosenman et 
al., 1999, 0421). Based on these findings and on the scientific 
evidence that respirable crystalline silica substantially increases the 
risk of each of these conditions, OSHA has determined that exposure to 
respirable crystalline silica increases the risk of ``material 
impairment of health or functional capacity'' within the meaning of the 
Occupational Safety and Health Act.
1. Silicosis
    OSHA considers silicosis, an irreversible and potentially fatal 
disease, to be a clear material impairment of health. The term 
``silicosis'' refers to a spectrum of lung diseases attributable to the 
inhalation of respirable crystalline silica. As described more fully in 
the Review of Health Effects Literature (Document ID 1711, pp. 16-71), 
the three types of silicosis are acute, accelerated, and chronic. Acute 
silicosis can occur within a few weeks to months after inhalation 
exposure to extremely high levels of respirable crystalline silica. 
Death from acute silicosis can occur within months to a few years of 
disease onset, with the affected person drowning in his or her own lung 
fluid (NIOSH, 1996, Document ID 0840). Accelerated silicosis results 
from exposure to high levels of airborne respirable crystalline silica, 
and disease usually occurs within 5 to 10 years of initial exposure 
(NIOSH, 1996, Document ID 0840). Both acute and accelerated silicosis 
are associated with exposures that are substantially above the previous 
general industry PEL, although no precise information on the 
relationships between exposure and occurrence of disease exists.
    Chronic silicosis is the most common form of silicosis seen today, 
and is a progressive and irreversible condition characterized as a 
diffuse nodular pulmonary fibrosis (NIOSH, 1996, Document ID 0840). 
Chronic silicosis generally occurs after 10 years or more of inhalation 
exposure to respirable crystalline silica at levels below those 
associated with acute and accelerated silicosis. Affected workers may 
have a dry chronic cough, sputum production, shortness of breath, and 
reduced pulmonary function. These symptoms result from airway 
restriction caused by the development of fibrotic scarring in the lower 
regions of the lungs. The scarring can be detected in chest x-ray films 
when the lesions become large enough to appear as visible opacities. 
The result is a restriction of lung volumes and decreased pulmonary 
compliance with concomitant reduced gas transfer. Chronic silicosis is 
characterized by small, rounded opacities that are symmetrically 
distributed in the upper lung zones on chest radiograph (Balaan and 
Banks, 1992, Document ID 0289, pp. 347, 350-351).
    The diagnosis of silicosis is based on a history of exposure to 
respirable crystalline silica, chest radiograph findings, and the 
exclusion of other conditions that appear similar. Because workers 
affected by early stages of chronic silicosis are often asymptomatic, 
the finding of opacities in the lung is key to detecting silicosis and 
characterizing its severity. The International Labour Organization 
(ILO) International Classification of Radiographs of Pneumoconioses 
(ILO, 1980, Document ID 1063; 2002, 1064) is the currently accepted 
standard against which chest radiographs are evaluated for use in 
epidemiological studies, medical surveillance, and clinical evaluation. 
The ILO system standardizes the description of chest x-rays, and is 
based on a 12-step scale of severity and extent of silicosis as 
evidenced by the size, shape, and density of opacities seen on the x-
ray film. Profusion (frequency) of small opacities is classified on a 
4-point major category scale (0-3), with each major category divided 
into three, giving a 12-point scale between 0/- and 3/+. Large 
opacities are defined as any opacity greater than 1 cm that is present 
in a film (ILO, 1980, Document ID 1063; 2002, 1064, p. 6).
    The small rounded opacities seen in early stage chronic silicosis 
(ILO major category 1 profusion) may progress (through ILO major 
categories 2 and/or 3) and develop into large fibrotic masses that 
destroy the lung architecture, resulting in progressive massive 
fibrosis (PMF). This stage of advanced silicosis is usually 
characterized by impaired pulmonary function, permanent disability, and 
premature death. In cases involving PMF, death is commonly attributable 
to progressive respiratory insufficiency (Balaan and Banks, 1992, 
Document ID 0289).
    Patients with ILO category 2 or 3 background profusion of small 
opacities are at increased risk, compared to those with category 1 
profusion, of developing the large opacities characteristic of PMF. In 
one study of silicosis patients in Hong Kong, Ng and Chan (1991, 
Document ID 1106, p. 231) found the risk of PMF increased by 42 and 64 
percent among patients whose chest x-

[[Page 16382]]

ray films were classified as ILO major category 2 or 3, respectively. 
Research has shown that people with silicosis advanced beyond ILO major 
category 1 have reduced life expectancy compared to the general 
population (Infante-Rivard et al., 1991, Document ID 1065; Ng et al., 
1992a, 0383; Westerholm, 1980, 0484).
    Silicosis is the oldest known occupational lung disease and is 
still today the cause of significant premature mortality. As discussed 
further in Section V.E, Comments and Responses Concerning Surveillance 
Data on Silicosis Morbidity and Mortality, in 2013, there were 111 
deaths in the U.S. where silicosis was recorded as an underlying or 
contributing cause of death on a death certificate (NCHS data). Between 
1996 and 2005, deaths attributed to silicosis resulted in an average of 
11.6 years of life lost by affected workers (NIOSH, 2007, Document ID 
1362). In addition, exposure to respirable crystalline silica remains 
an important cause of morbidity and hospitalizations. National 
inpatient hospitalization data show that in the year 2011, 2,082 
silicosis-related hospitalizations occurred, indicating that silicosis 
continues to be a significant health issue in the U.S. (Document ID 
3577, Tr. 854-855). Although there is no national silicosis disease 
surveillance system in the U.S., a published analysis of state-based 
surveillance data from the time period 1987-1996 estimated that between 
3,600-7,000 new cases of silicosis occurred in the U.S. each year 
(Rosenman et al., 2003, Document ID 1166).
    It has been widely reported that available statistics on silicosis-
related mortality and morbidity are likely to be understated due to 
misclassification of causes of death (for example, as tuberculosis, 
chronic bronchitis, emphysema, or cor pulmonale), lack of occupational 
information on death certificates, or misdiagnosis of disease by health 
care providers (Goodwin et al., 2003, Document ID 1030; Windau et al., 
1991, 0487; Rosenman et al., 2003, 1166). Furthermore, reliance on 
chest x-ray findings may miss cases of silicosis because fibrotic 
changes in the lung may not be visible on chest radiograph; thus, 
silicosis may be present absent x-ray signs or may be more severe than 
indicated by x-ray (Hnizdo et al., 1993, Document ID 1050; Craighhead 
and Vallyahan, 1980, 0995; Rosenman et al., 1997, 4181).
    Although most workers with early-stage silicosis (ILO categories 0/
1 or 1/0) typically do not experience respiratory symptoms, the primary 
risk to the affected worker is progression of disease with progressive 
decline of lung function. Several studies of workers exposed to 
crystalline silica have shown that, once silicosis is detected by x-
ray, a substantial proportion of affected workers can progress beyond 
ILO category 1 silicosis, even after exposure has ceased (e.g., Hughes, 
1982, Document ID 0362; Hessel et al., 1988, 1042; Miller et al., 1998, 
0374; Ng et al., 1987a, 1108; Yang et al., 2006, 1134). In a population 
of coal miners whose last chest x-ray while employed was classified as 
major category 0, and who were examined again 10 years after the mine 
had closed, 20 percent had developed opacities consistent with a 
classification of at least 1/0, and 4 percent progressed further to at 
least 2/1 (Miller et al., 1998, Document ID 0374). Although there were 
periods of extremely high exposure to respirable quartz in the mine 
(greater than 2,000 [mu]g/m\3\ in some jobs between 1972 and 1976, and 
more than 10 percent of exposures between 1969 and 1977 were greater 
than 1,000 [mu]g/m\3\), the mean cumulative exposure for the cohort 
over the period 1964-1978 was 1.8 mg/m\3\-yrs, corresponding to an 
average silica concentration of 120 [mu]g/m\3\. In a population of 
granite quarry workers exposed to an average respirable silica 
concentration of 480 [mu]g/m\3\ (mean length of employment was 23.4 
years), 45 percent of those diagnosed with simple silicosis (i.e., 
presence of small opacities only on chest x-ray films) showed 
radiological progression of disease after 2 to 10 years of follow up 
(Ng et al., 1987a, Document ID 1108). Among a population of gold 
miners, 92 percent progressed in 14 years; exposures of high-, medium-, 
and low-exposure groups were 970, 450, and 240 [mu]g/m\3\, respectively 
(Hessel et al., 1988, Document ID 1042). Chinese mine and factory 
workers categorized under the Chinese system of x-ray classification as 
``suspected'' silicosis cases (analogous to ILO 0/1) had a progression 
rate to stage I (analogous to ILO major category 1) of 48.7 percent, 
and the average interval was about 5.1 years (Yang et al., 2006, 
Document ID 1134).
    The risk of silicosis carries with it an increased risk of reduced 
lung function as the disease irreversibly progresses. There is strong 
evidence in the literature for the finding that lung function 
deteriorates more rapidly in workers exposed to silica, especially 
those with silicosis, than what is expected from a normal aging process 
(Cowie, 1988, Document ID 0993; Hughes et al., 1982, 0362; Malmberg et 
al., 1993, 0370; Ng and Chan, 1992, 1107). The rates of decline in lung 
function are greater in those whose disease showed evidence of 
radiologic progression (Begin et al., 1987, Document ID 0295; Cowie, 
1988, 0993; Ng and Chan, 1992, 1107; Ng et al., 1987a, 1108). 
Additionally, the average deterioration of lung function exceeds that 
in smokers (Hughes et al., 1982, Document ID 0362).
    Several studies have reported no decrease in pulmonary function 
with an ILO category 1 level of profusion of small opacities but found 
declines in pulmonary function with categories 2 and 3 (Ng et al., 
1987a, Document ID 1108; Begin et al., 1988, 0296; Moore et al., 1988, 
1099). However, one study found a statistically significantly greater 
annual loss in forced vital capacity (FVC) and forced expiratory volume 
in one second (FEV1) among those with category 1 profusion 
compared to category 0 (Cowie, 1988, Document ID 0993). In another 
study, the degree of profusion of opacities was associated with 
reductions in several pulmonary function metrics (Cowie and Mabena, 
1991, Document ID 0342). Some studies have reported no associations 
between radiographic silicosis and decreases in pulmonary function (Ng 
et al., 1987a, Document ID 1108; Wiles et al., 1972, 0485; Hnizdo, 
1992, 1046), while other studies (Ng et al., 1987a, Document ID 1108; 
Wang et al., 1997, 0478) have found that measurable changes in 
pulmonary function are evident well before the changes seen on chest x-
ray. Findings of pulmonary function decrements absent radiologic signs 
of silicosis may reflect the general insensitivity of chest radiography 
in detecting lung fibrosis, or may also reflect that exposure to 
respirable silica has been shown to increase the risk of non-malignant 
respiratory disease (NMRD) and its attendant pulmonary function losses 
(see Section V.C, Summary of the Review of Health Effects Literature 
and Preliminary QRA).
    Moreover, exposure to respirable crystalline silica in and of 
itself, with or without silicosis, increases the risk that latent 
tuberculosis infection can convert to active disease. Early 
descriptions of dust diseases of the lung did not distinguish between 
TB and silicosis, and most fatal cases described in the first half of 
this century were a combination of silicosis and TB (Castranova et al., 
1996, Document ID 0314). More recent findings demonstrate that exposure 
to silica, even without silicosis, increases the risk of infectious 
(i.e., active) pulmonary TB (Sherson and Lander, 1990, Document ID 
0434; Cowie, 1994, 0992; Hnizdo and Murray, 1998, 0360; teWaterNaude et 
al., 2006, 0465). Both conditions together can

[[Page 16383]]

hasten the development of respiratory impairment and increase mortality 
risk even beyond that experienced by persons with active TB who have 
not been exposed to respirable crystalline silica (Banks, 2005, 
Document ID 0291).
    Based on the information presented above and in its review of the 
health literature, OSHA concludes that silicosis remains a significant 
cause of early death and of serious illness, despite the existence of 
an enforceable exposure limit over the past 40 years. Silicosis in its 
later stages of progression (i.e., with chest x-ray findings of ILO 
category 2 or 3 profusion of small opacities, or the presence of large 
opacities) is characterized by the likely appearance of respiratory 
symptoms and decreased pulmonary function, as well as increased risk of 
progression to PMF, disability, and early mortality. Early-stage 
silicosis, although without symptoms among many who are affected, 
nevertheless reflects the formation of fibrotic lesions in the lung and 
increases the risk of progression to later stages, even after exposure 
to respirable crystalline silica ceases. In addition, the presence of 
silicosis increases the risk of pulmonary infections, including 
conversion of latent TB infection to active TB. Silicosis is not a 
reversible condition, and there is no specific treatment for the 
disease, other than administration of drugs to alleviate inflammation 
and maintain open airways, or administration of oxygen therapy in 
severe cases. Based on these considerations, OSHA finds that silicosis 
of any form, and at any stage of progression, is a material impairment 
of health and that fibrotic scarring of the lungs represents loss of 
functional respiratory capacity.
2. Lung Cancer
    OSHA considers lung cancer, an irreversible and frequently fatal 
disease, to be a clear material impairment of health (see Homer et al., 
2009, Document ID 1343). According to the National Cancer Institute 
(SEER Cancer Statistics Review, 2006, Document ID 1343), the five-year 
survival rate for all forms of lung cancer is only 15.6 percent, a rate 
that has not improved in nearly two decades. After reviewing the record 
as a whole, OSHA finds that respirable crystalline silica exposure 
substantially increases the risk of lung cancer. This finding is based 
on the best available toxicological and epidemiological data, reflects 
substantial supportive evidence from animal and mechanistic research, 
and is consistent with the conclusions of other government and public 
health organizations, including the International Agency for Research 
on Cancer (1997, Document ID 1062; 2012, Document ID 1473), the HHS 
National Toxicology Program (2000, Document ID 1417), the CDC's 
National Institute for Occupational Safety and Health (2002, Document 
ID 1110), the American Thoracic Society (1997, Document ID 0283), and 
the American Conference of Governmental Industrial Hygienists (2010, 
Document ID 0515).
    The Agency's primary evidence comes from evaluation of more than 50 
studies of occupational cohorts from many different industry sectors in 
which exposure to respirable crystalline silica occurs, including: 
Granite and stone quarrying; the refractory brick industry; gold, tin, 
and tungsten mining; the diatomaceous earth industry; the industrial 
sand industry; and construction. In addition, the association between 
exposure to respirable crystalline silica and lung cancer risk was 
reported in a national mortality surveillance study (Calvert et al., 
2003, Document ID 0309) and in two community-based studies (Pukkala et 
al., 2005, Document ID 0412; Cassidy et al., 2007, 0313), as well as in 
a pooled analysis of 10 occupational cohort studies (Steenland et al., 
2001a, Document ID 0452). Toxicity studies provide supportive evidence 
of the carcinogenicity of crystalline silica, in that they demonstrate 
biologically plausible mechanisms by which crystalline silica in the 
deep lung can give rise to biochemical and cellular events leading to 
tumor development (see Section V.H, Mechanisms of Silica-Induced 
Adverse Health Effects).
3. Non-Malignant Respiratory Disease (NMRD) (Other Than Silicosis)
    Although many of the stakeholders in this rule have focused their 
attention on the evidence related to silicosis and lung cancer, the 
available evidence shows that exposure to respirable crystalline silica 
also increases the risk of developing NMRD, in particular chronic 
bronchitis and emphysema. OSHA has determined that NMRD, which results 
in loss of pulmonary function that restricts normal activity in 
individuals afflicted with these conditions (see American Thoracic 
Society, 2003, Document ID 1332), constitutes a material impairment of 
health. Both chronic bronchitis and emphysema can occur in conjunction 
with the development of silicosis. Several studies have documented 
increased prevalence of chronic bronchitis and emphysema among silica-
exposed workers even absent evidence of silicosis (see Document ID 
1711, pp. 182-192; NIOSH, 2002, 1110; American Thoracic Society, 2003, 
1332). There is also evidence that smoking may have an additive or 
synergistic effect on silica-related NMRD morbidity or mortality 
(Hnizdo, 1990, Document ID 1045; Hnizdo et al., 1990, 1047; Wyndham et 
al., 1986, 0490; NIOSH, 2002, 1110). In a study of diatomaceous earth 
workers, Park et al. (2002, Document ID 0405) found a positive 
exposure-response relationship between exposure to respirable 
cristobalite (a form of silica) and increased mortality from NMRD.
    Decrements in pulmonary function have often been found among 
workers exposed to respirable crystalline silica absent radiologic 
evidence of silicosis. Several cross-sectional studies have reported 
such findings among granite workers (Theriault et al., 1974a, Document 
ID 0466; Wallsh, 1997, 0477; Ng et al., 1992b, 0387; Montes II et al., 
2004b, 0377), gold miners (Irwig and Rocks, 1978, Document ID 1067; 
Hnizdo et al., 1990, 1047; Cowie and Mabena, 1991, 0342), gemstone 
cutters (Ng et al., 1987b, Document ID 1113), concrete workers (Meijer 
et al., 2001, Document ID 1243), refractory brick workers (Wang et al., 
1997, Document ID 0478), hard rock miners (Manfreda et al., 1982, 
Document ID 1094; Kreiss et al., 1989, 1079), pottery workers (Neukirk 
et al., 1994, Document ID 0381), slate workers (Surh, 2003, Document ID 
0462), and potato sorters exposed to silica in diatomaceous earth 
(Jorna et al, 1994, Document ID 1071).
    OSHA also evaluated several longitudinal studies where exposed 
workers were examined over a period of time to track changes in 
pulmonary function. Among both active and retired granite workers 
exposed to an average of 60 [mu]g/m \3\, Graham et al. did not find 
exposure-related decrements in pulmonary function (1981, Document ID 
1280; 1984, 0354). However, Eisen et al. (1995, Document ID 1010) did 
find significant pulmonary decrements among a subset of granite workers 
(termed ``dropouts'') who left work and consequently did not 
voluntarily participate in the last of a series of annual pulmonary 
function tests. This group of workers experienced steeper declines in 
FEV1 compared to the subset of workers who remained at work and 
participated in all tests (termed ``survivors''), and these declines 
were significantly related to dust exposure. Thus, in this study, 
workers who had left work had exposure-related declines in pulmonary 
function to a greater extent than did workers who remained on the job, 
clearly demonstrating a survivor effect among the active

[[Page 16384]]

workers. Exposure-related changes in lung function were also reported 
in a 12-year study of granite workers (Malmberg, 1993, Document ID 
0370), in two 5-year studies of South African miners (Hnizdo, 1992, 
Document ID 1046; Cowie, 1988, 0993), and in a study of foundry workers 
whose lung function was assessed between 1978 and 1992 (Hertzberg et 
al., 2002, Document ID 0358).
    Each of these studies reported their findings in terms of rates of 
decline in any of several pulmonary function measures, such as FVC, 
FEV1, and FEV1/FVC. To put these declines in 
perspective, Eisen et al. (1995, Document ID 1010) reported that the 
rate of decline in FEV1 seen among the dropout subgroup of 
Vermont granite workers was 4 ml per mg/m\3\-yrs of exposure to 
respirable granite dust; by comparison, FEV1 declines at a 
rate of 10 ml/year from smoking one pack of cigarettes daily. From 
their study of foundry workers, Hertzberg et al., reported finding a 
1.1 ml/year decline in FEV1 and a 1.6 ml/year decline in FVC 
for each mg/m\3\-yrs of respirable silica exposure after controlling 
for ethnicity and smoking (2002, Document ID 0358, p. 725). From these 
rates of decline, they estimated that exposure to the previous OSHA 
general industry quartz standard of 100 [micro]g/m\3\ for 40 years 
would result in a total loss of FEV1 and FVC that is less 
than but still comparable to smoking a pack of cigarettes daily for 40 
years. Hertzberg et al. also estimated that exposure to the current 
standard for 40 years would increase the risk of developing abnormal 
FEV1 or FVC by factors of 1.68 and 1.42, respectively (2002, Document 
ID 0358, pp. 725-726). OSHA believes that this magnitude of reduced 
pulmonary function, as well as the increased morbidity and mortality 
from non-malignant respiratory disease (NMRD) that has been documented 
in the studies summarized above, constitute material impairments of 
health and loss of functional respiratory capacity.
4. Renal and Autoimmune Effects
    Finally, OSHA's review of the literature reflects substantial 
evidence that exposure to crystalline silica increases the risk of 
renal and autoimmune diseases, both of which OSHA considers to be 
material impairments of health (see Section V.C, Summary of the Review 
of Health Effects Literature and Preliminary QRA). Epidemiological 
studies have found statistically significant associations between 
occupational exposure to silica dust and chronic renal disease (e.g., 
Calvert et al., 1997, Document ID 0976), subclinical renal changes 
including proteinurea and elevated serum creatinine (e.g., Ng et al., 
1992c, Document ID 0386; Rosenman et al., 2000, 1120; Hotz, et al., 
1995, 0361), end-stage renal disease morbidity (e.g., Steenland et al., 
1990, Document ID 1125), chronic renal disease mortality (Steenland et 
al., 2001b, Document ID 0456; 2002a, 0448), and granulomatosis with 
polyangitis (Nuyts et al., 1995, Document ID 0397). Granulomatosis with 
polyangitis is characterized by inflammation of blood vessels, leading 
to damaging granulomatous formation in the lung and damage to the 
glomeruli of the kidneys, a network of capillaries responsible for the 
first stage of blood filtration. If untreated, this condition often 
leads to renal failure (Nuyts et al., 1995, Document ID 0397, p. 1162). 
Possible mechanisms for silica-induced renal disease include a direct 
toxic effect on the kidney and an autoimmune mechanism (see Section 
V.H, Mechanisms of Silica-Induced Adverse Health Effects; Calvert et 
al., 1997, Document ID 0976; Gregorini et al., 1993, 1032). Steenland 
et al. (2002a, Document ID 0448) demonstrated a positive exposure-
response relationship between exposure to respirable crystalline silica 
and end-stage renal disease mortality.
    In addition, there are a number of studies that show exposure to be 
related to increased risks of autoimmune disease, including scleroderma 
(e.g., Sluis-Cremer et al., 1985, Document ID 0439), rheumatoid 
arthritis (e.g., Klockars et al., 1987, Document ID 1075; Rosenman and 
Zhu, 1995, 0424), and systemic lupus erythematosus (e.g., Brown et al., 
1997, Document ID 0974). Scleroderma is a degenerative disorder that 
leads to over-production of collagen in connective tissue that can 
cause a wide variety of symptoms including skin discoloration and 
ulceration, joint pain, swelling and discomfort in the extremities, 
breathing problems, and digestive problems. Rheumatoid arthritis is 
characterized by joint pain and tenderness, fatigue, fever, and weight 
loss. Systemic lupus erythematosus is a chronic disease of connective 
tissue that can present a wide range of symptoms including skin rash, 
fever, malaise, joint pain, and, in many cases, anemia and iron 
deficiency. OSHA considers chronic renal disease, end-stage renal 
disease mortality, granulomatosis with polyangitis, scleroderma, 
rheumatoid arthritis, and systemic lupus erythematosus clearly to be 
material impairments of health.

C. OSHA's Final Quantitative Risk Estimates

    To evaluate the significance of the health risks that result from 
exposure to hazardous chemical agents, OSHA relies on epidemiological 
and experimental data, as well as statistical methods. The Agency uses 
these data and methods to characterize the risk of disease resulting 
from workers' exposure to a given hazard over a working lifetime at 
levels of exposure reflecting both compliance with previous standards 
and compliance with the new standard. In the case of respirable 
crystalline silica, the previous general industry, construction, and 
shipyard PELs were formulas that limit 8-hour TWA exposures to 
respirable dust; the limit on exposure decreased with increasing 
crystalline silica content of the dust. OSHA's previous general 
industry PEL for respirable quartz was expressed both in terms of a 
particle count and a gravimetric concentration, while the previous 
construction and shipyard employment PELs for respirable quartz were 
only expressed in terms of a particle count formula. For general 
industry, the gravimetric formula PEL for quartz approaches 100 
[micro]g/m\3\ of respirable crystalline silica when the quartz content 
of the dust is about 10 percent or greater. The previous PEL's particle 
count formula for the construction and shipyard industries is equal to 
a range of about 250 [mu]g/m\3\ to 500 [mu]g/m\3\ expressed as 
respirable quartz. In general industry, the previous PELs for 
cristobalite and tridymite, which are forms (polymorphs) of silica, 
were one-half the PEL for quartz.
    In this final rule, OSHA has established a uniform PEL for 
respirable crystalline silica by revising the PELs applicable to 
general industry, construction, and maritime to 50 [mu]g/m\3\ TWA of 
respirable crystalline silica. OSHA has also established an action 
level of 25 [micro]g/m\3\ TWA. In this section of the preamble, OSHA 
presents its final estimates of health risks associated with a working 
lifetime (45 years) of exposure to 25, 50, and 100 [micro]g/m\3\ 
respirable crystalline silica. These levels represent the risks 
associated with exposure over a working lifetime to the new action 
level, new PEL, and previous general industry PEL, respectively. OSHA 
also presents estimates associated with exposure to 250 and 500 
[micro]g/m\3\ to represent a range of risks likely to be associated 
with exposure to the former construction and shipyard PELs. Risk 
estimates are presented for mortality due to lung cancer, silicosis and 
other non-malignant respiratory disease (NMRD),

[[Page 16385]]

and end-stage renal disease, as well as silicosis morbidity. These 
estimates are the product of OSHA's risk assessment, following the 
Agency's consideration of new data introduced into the rulemaking 
record and of the numerous comments in the record that raised questions 
about OSHA's preliminary findings and analysis.
    After reviewing the evidence and testimony in the record, OSHA has 
determined that it is appropriate to base its final risk estimates on 
the same studies and models as were used in the NPRM (see Section V.C, 
Summary of the Review of Health Effects Literature and Preliminary 
QRA). For mortality risk estimates, OSHA used the models developed by 
various investigators and employed a life table analysis to implement 
the models using the same background all-cause mortality data and 
consistent assumption for length of lifetime (85 years). The life table 
is a technique that allows estimation of excess risk of disease 
mortality factoring in the probability of surviving to a particular age 
assuming no exposure to the agent in question and given the background 
probability of dying from any cause at or before that age (see Section 
V.M, Comments and Responses Concerning Working Life, Life Tables, and 
Dose Metric). Since the time of OSHA's preliminary analysis, the 
National Center for Health Statistics (NCHS) released updated all-cause 
mortality background rates from 2011; these rates are available in an 
internet web-based query by year and 2010 International Classification 
of Diseases (ICD) code through the Centers of Disease Control and 
Prevention (CDC) Wonder database (http://wonder.cdc.gov/udc-icd10.html). Using these updated statistics, OSHA revised its life 
table analyses to estimate lifetime risks of mortality that result from 
45 years of exposure to respirable crystalline silica. OSHA's final 
quantitative mortality risk estimates are presented in Table VI-1 
below.
    For silicosis morbidity risk estimates, OSHA relied on the 
cumulative risk models developed by investigators of five studies who 
conducted studies relating cumulative disease risk to cumulative 
exposure to respirable crystalline silica (see footnotes to Table VI-
1). Of these, only one, the study by Steenland and Brown (1995) of U.S. 
gold miners, employed a life-table analysis. Table VI-1 also presents 
OSHA's final quantitative estimates of silicosis morbidity risks.
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    OSHA notes that the updated risk estimates are not substantially 
different from those presented in the Preliminary QRA; for example, for 
exposure at the previous general industry PEL approaching 100 [mu]g/
m\3\, the excess lung cancer mortality risk ranged from 13 to 60 deaths 
per 1,000 workers using the original 2006 background data, and from 11 
to 54 deaths per 1,000 workers using the updated 2011 background data. 
For exposure at the revised PEL of 50 [mu]g/m\3\, the risk estimates 
ranged from 6 to 26 deaths per 1,000 workers using the 2006 background 
data, and 5 to 23 deaths per 1,000 workers using the 2011 background 
data. Similarly, the updated risk estimates for NMRD are not 
substantially different; for example, for exposure for 45 working years 
at the previous general industry PEL approaching 100 [mu]g/m\3\, the 
excess NMRD mortality risk, using the Park et al. (2002, Document 0405) 
model was 83 deaths per 1,000 workers using the original 2006 
background data, and 85 deaths per 1,000 workers using the updated 2011 
background data. For exposure at the revised PEL of 50 [mu]g/m\3\, the 
risk estimate was 43 deaths per 1,000 workers using the 2006 background 
data, and 44 deaths per 1,000 workers using the 2011 background data.
    OSHA also presents in the table the excess lung cancer mortality 
risk associated with 45 years of exposure to the previous construction/
shipyard PEL (in the range of 250 to 500 [micro]g/m\3\). It should be 
noted, however, that exposure to 250 or 500 [micro]g/m\3\ over 45 years 
represents cumulative exposures of 11.25 and 22.5 mg/m\3\-yrs, 
respectively, which are well above the median cumulative exposure for 
most of the cohorts used in the risk assessment. Estimating excess 
risks over this higher range of cumulative exposures required some 
degree of extrapolation, which adds uncertainty. In addition, at 
cumulative exposures as high as permitted by the previous construction 
and maritime PELs, silica-related causes of mortality will compete with 
each other and it is difficult to determine the risk of any single 
cause of mortality in the face of such competing risks.
    OSHA's final risk estimates for renal disease reflect the 1998 
background all-cause mortality and renal mortality rates for U.S. 
males, rather than the 2011 rates used for lung cancer and NMRD, as 
updated in the previous sections. Background rates were not adjusted 
for the renal disease risk estimates because the CDC significantly 
changed the classification of renal diseases after 1998; they are now 
inconsistent with those used by Steenland et al. (2002a, Document ID 
0448), the study relied on by OSHA, to ascertain the cause of death of 
workers in their study. OSHA notes that the change in classification 
system, from ICD-9 to ICD-10, did not materially affect background 
rates for diseases grouped as lung cancer or NMRD. The findings from 
OSHA's final risk assessment are summarized below.
    OSHA notes that the key studies in its final risk assessment were 
composed of

[[Page 16388]]

cohorts with cumulative exposures relevant to those permitted by the 
preceding General Industry PEL (45 years of exposure at 100 [mu]g/m\3\ 
equals 4.5 mg/m\3\-yrs). Table VI-2 provides the reported cumulative 
exposure information for each of the cohorts of the key studies. Most 
of these cohorts had mean or median cumulative exposures below 4.5 mg/
m\3\-yrs. Based on this data, OSHA concludes that the cumulative 
exposures experienced by the cohorts are relevant and reasonable for 
use in the Agency's final risk assessment.
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1. Summary of Excess Risk Estimates for Lung Cancer Mortality
    For estimates of lung cancer risk from crystalline silica exposure, 
OSHA has relied upon studies of exposure-response relationships 
presented in a pooled analysis of 10 cohort studies (Steenland et al., 
2001a, Document ID 0452; ToxaChemica, Inc., 2004, 0469) as well as on 
individual studies of granite (Attfield and Costello, 2004, Document ID 
0543), diatomaceous earth (Rice et al., 2001, Document ID 1118), and 
industrial sand (Hughes et al., 2001, Document ID 1060) worker cohorts, 
and a study of coal miners exposed to respirable crystalline silica 
(Miller et al., 2007, Document ID 1305; Miller and MacCalman, 2009, 
1306). OSHA found these studies to have been suitable for use to 
quantitatively characterize health risks to exposed workers because: 
(1) Study populations were of sufficient size to provide adequate 
statistical power to detect low levels of risk; (2) sufficient 
quantitative exposure data were available over a sufficient span of 
time to characterize cumulative exposures of cohort members to 
respirable crystalline silica; (3) the studies either adjusted for or 
otherwise adequately addressed confounding factors such as smoking and 
exposure to other carcinogens; and (4) investigators developed 
quantitative assessments of exposure-response relationships using 
appropriate statistical models or otherwise provided sufficient 
information that permits OSHA to do so. OSHA implemented all risk 
models in its own life table analysis so that the use of background 
lung cancer rates and assumptions regarding length of exposure and 
lifetime were consistent across each of the models, and so OSHA could 
estimate lung cancer risks associated with exposure to specific levels 
of silica of interest to the Agency.
    The Steenland et al. (2001a, Document ID 0452) study consisted of a 
pooled exposure-response analysis and risk assessment based on raw data 
obtained for ten cohorts of silica-exposed workers (65,980 workers, 
1,072 lung cancer deaths). The cohorts in this pooled analysis include 
U.S. gold miners (Steenland and Brown, 1995a, Document ID 0450), U.S. 
diatomaceous earth workers (Checkoway et al., 1997, Document ID 0326), 
Australian gold miners (de Klerk and Musk, 1998, Document ID 0345), 
Finnish granite workers (Koskela et al., 1994, Document ID 1078), South 
African gold miners (Hnizdo et al., 1997, Document ID 1049), U.S. 
industrial sand workers (Steenland et al., 2001b, Document ID 0456), 
Vermont granite workers (Costello and Graham, 1988, Document ID 0991), 
and Chinese pottery workers, tin miners, and tungsten miners (Chen et 
al., 1992, Document ID 0329). To determine the exposure-response 
relationship between silica exposures and lung cancer, the 
investigators used a nested case-control design with cases and controls 
matched for race, sex, age (within five years), and study; 100 controls 
were matched for each case. An extensive exposure assessment for this 
pooled analysis was developed and published by Mannetje et al. (2002a, 
Document ID 1090).
    Using ToxaChemica's study (2004, Document ID 0469) of this pooled 
data, the estimated excess lifetime lung cancer risk associated with 45 
years of exposure to 100 [mu]g/m\3\ (about equal to the previous 
general industry PEL) is between 20 and 26 deaths per 1,000 workers. 
The estimated excess lifetime risk associated with 45 years of exposure 
to silica concentrations in the range of 250 and 500 [mu]g/m\3\ (about 
equal to the previous construction and shipyard PELs) is between 24 and 
33 deaths per 1,000. At the final PEL of 50 [mu]g/m\3\, the estimated 
excess lifetime risk ranges from 16 to 23 deaths per 1,000, and, at the 
action level of 25 [mu]g/m\3\, from 10 to 21 deaths per 1,000.
    In addition to the pooled cohort study, OSHA's Final Quantitative 
Risk Assessment presents risk estimates in Table VI-1 derived from four 
individual studies where investigators presented either lung cancer 
risk estimates or exposure-response coefficients. Two of these studies, 
one on diatomaceous earth workers (Rice et al., 2001, Document ID 1118) 
and one on Vermont granite workers (Attfield and Costello, 2004, 
Document ID 0543), were included in the 10-cohort pooled study 
(Steenland et al., 2001a, Document ID 0452; ToxaChemica Inc., 2004, 
0469). The other two were of British coal miners (Miller et al., 2007, 
Document ID 1305; Miller and MacCalman, 2009,1306) and North American 
industrial sand workers (Hughes et al., 2001, Document ID 1060).
    Rice et al. (2001, Document ID 1118) presented an exposure-response 
analysis of the diatomaceous worker cohort studied by Checkoway et al. 
(1993, Document ID 0324; 1996, 0325; 1997, 0326), who found a 
significant relationship between exposure to respirable cristobalite 
and increased lung cancer mortality. From this cohort the estimates of 
the excess risk of lung cancer mortality are 30, 15, and 8 deaths per 
1,000 workers for 45 years of exposure to 100, 50, and 25 [mu]g/m\3\, 
respectively. For exposures in the range of the current construction 
and shipyard PELs over 45 years, estimated risks lie in a range between 
72 and 137 excess deaths per 1,000 workers.
    Somewhat higher risk estimates are derived from the analysis 
presented by Attfield and Costello (2004, Document ID 0543) of Vermont 
granite workers. OSHA's use of this analysis yielded a risk estimate of 
54 excess deaths per 1,000 workers for 45 years of exposure to the 
previous general industry PEL of 100 [mu]g/m\3\, 22 excess deaths per 
1,000 for 45 years of exposure to the final PEL of 50 [mu]g/m\3\, and 
10 excess deaths per 1,000 for 45 years of exposure at the action level 
of 25 [mu]g/m\3\. Estimated excess risks associated with 45 years of 
exposure at the current construction PEL range from 231 to 657 deaths 
per 1,000.
    Hughes et al. (2001, Document ID 1060) conducted a study of 
industrial sand workers in the U.S. and Canada. Using this study, OSHA 
estimated cancer risks of 33, 14, and 7 deaths per 1,000 for 45 years 
exposure to the previous general industry PEL of 100 [mu]g/m\3\, the 
final PEL of 50 [mu]g/m\3\, and the final action level of 25 [mu]g/m\3\ 
respirable crystalline silica, respectively. For 45 years of exposure 
to the previous construction PEL, estimated risks range from 120 to 407 
deaths per 1,000 workers.
    Miller and MacCalman (2010, Document ID 1306; also reported in 
Miller et al., 2007, Document ID 1305) presented a study of miners from 
10 coal mines in the U.K. Based on this study, OSHA estimated the 
lifetime lung cancer mortality risk to be 11 per 1,000 workers for 45 
years of exposure to 100 [mu]g/m\3\ respirable crystalline silica. For 
the final PEL of 50 [mu]g/m\3\ and action level of 25 [mu]g/m\3\, the 
lifetime risks are estimated to be 5 and 3 deaths per 1,000, 
respectively. The range of risks estimated to result from 45 years of 
exposure to the previous construction and shipyard PELs is from 33 to 
86 deaths per 1,000 workers.
2. Summary of Risk Estimates for Silicosis and Other Chronic Lung 
Disease Mortality
    OSHA based its quantitative assessment of silicosis mortality risks 
on a pooled analysis conducted by Mannetje et al. (2002b, Document ID 
1089) of data from six of the ten epidemiological studies in the 
Steenland et al. (2001a, Document ID 0452) pooled analysis of lung 
cancer mortality that also included extensive data on silicosis. 
Cohorts included in the silicosis study were: U.S. diatomaceous earth 
workers (Checkoway et al., 1997, Document ID 0326); Finnish granite 
workers (Koskela

[[Page 16390]]

et al., 1994, Document ID 1078); U.S. granite workers (Costello and 
Graham, 1988, Document ID 0991); U.S. industrial sand workers 
(Silicosis and Silicate Disease Committee, 1988, Document ID 0455); 
U.S. gold miners (Steenland and Brown, 1995b, Document ID 0451); and 
Australian gold miners (de Klerk and Musk, 1998, Document ID 0345). 
These six cohorts contained 18,634 workers and 170 silicosis deaths, 
where silicosis mortality was defined as death from silicosis (ICD-9 
502, n = 150) or from unspecified pneumoconiosis (ICD-9 505, n = 20). 
Although Mannetje et al, (2002b, Document ID 1089) estimated silicosis 
risks from a Poisson regression, a subsequent analysis was conducted by 
Steenland and Bartell (ToxaChemica, 2004, Document ID 0469) based on a 
case control design. Based on the Steenland and Bartell analysis, OSHA 
estimated that the lifetime risk of silicosis mortality associated with 
45 years of exposure to the previous general industry PEL of 100 [mu]g/
m\3\ is 11 deaths per 1,000 workers. Exposure for 45 years to the final 
PEL of 50 [mu]g/m\3\ results in an estimated 7 silicosis deaths per 
1,000, and exposure for 45 years to the final action level of 25 [mu]g/
m\3\ results in an estimated 4 silicosis deaths per 1,000. Lifetime 
risks associated with exposure at the previous construction and 
shipyard PELs range from 17 to 22 deaths per 1,000 workers.
    To study non-malignant respiratory diseases (NMRD), of which 
silicosis is one, Park et al. (2002, Document ID 0405) analyzed the 
California diatomaceous earth cohort data originally studied by 
Checkoway et al. (1997, Document ID 0326). The authors quantified the 
relationship between exposure to cristobalite and mortality from NMRD. 
Diseases in this category included pneumoconiosis (which includes 
silicosis), chronic bronchitis, and emphysema, but excluded pneumonia 
and other infectious diseases. Because of the broader range of silica-
related diseases examined by Park et al., OSHA's estimates of the 
lifetime chronic lung disease mortality risk based on this study are 
substantially higher than those that OSHA derived from the Mannetje et 
al. (2002b, Document ID 1089) silicosis analysis. For the previous 
general industry PEL of 100 [mu]g/m\3\, exposure for 45 years is 
estimated to result in 85 excess deaths per 1,000 workers. At the final 
PEL of 50 [mu]g/m\3\ and action level of 25 [mu]g/m\3\, OSHA estimates 
the lifetime risk from 45 years of exposure to be 44 and 22 excess 
deaths per 1,000, respectively. The range of risks associated with 
exposure at the former construction and shipyard PELs over a working 
lifetime is from 192 to 329 excess deaths per 1,000 workers.
3. Summary of Risk Estimates for Renal Disease Mortality
    OSHA's analysis of the health effects literature included several 
studies that have demonstrated that exposure to respirable crystalline 
silica increases the risk of renal and autoimmune disease (see Document 
ID 1711, Review of Health Effects Literature and Preliminary QRA, pp. 
208-229). For autoimmune disease, there was insufficient data on which 
to base a quantitative risk assessment. OSHA's assessment of the renal 
disease risks that result from exposure to respirable crystalline 
silica is based on an analysis of pooled data from three cohort studies 
(Steenland et al., 2002a, Document ID 0448). The combined cohort for 
the pooled analysis (Steenland et al., 2002a, Document ID 0448) 
consisted of 13,382 workers and included industrial sand workers 
(Steenland et al., 2001b, Document ID 0456), U.S. gold miners 
(Steenland and Brown, 1995a, Document ID 0450), and Vermont granite 
workers (Costello and Graham, 1988, Document ID 0991). Exposure data 
were available for 12,783 workers and analyses conducted by the 
original investigators demonstrated monotonically increasing exposure-
response trends for silicosis, indicating that exposure estimates were 
not likely subject to significant random misclassification. The mean 
duration of exposure, cumulative exposure, and concentration of 
respirable silica for the combined cohort were 13.6 years, 1.2 mg/m\3\-
years, and 70 [mu]g/m\3\, respectively. There were highly statistically 
significant trends for increasing renal disease mortality with 
increasing cumulative exposure for both multiple cause analysis of 
mortality (p < 0.000001) and underlying cause analysis (p = 0.0007). 
OSHA's estimates of renal disease mortality risk based on this study 
are 39 deaths per 1,000 for 45 years of exposure at the previous 
general industry PEL of 100 [mu]g/m\3\, 32 deaths per 1,000 for 
exposure at the final PEL of 50 [mu]g/m\3\, and 25 deaths per 1,000 at 
the action level of 25 [mu]g/m\3\. OSHA also estimates that 45 years of 
exposure at the previous construction and shipyard PELs would result in 
a renal disease excess mortality risk ranging from 52 to 63 deaths per 
1,000 workers. OSHA acknowledges that the risk estimates for end-stage 
renal disease mortality are less robust than those for silicosis, lung 
cancer, and NMRD, and are thus more uncertain.
4. Summary of Risk Estimates for Silicosis Morbidity
    OSHA's Final Quantitative Risk Assessment is based on several 
cross-sectional studies designed to characterize relationships between 
exposure to respirable crystalline silica and development of silicosis 
as determined by chest radiography. Due to the long latency periods 
associated with silicosis, OSHA relied on those studies that were able 
to contact and evaluate many of the workers who had retired. OSHA 
believes that relying on studies that included retired workers comes 
closest to characterizing lifetime risk of silicosis morbidity. OSHA 
identified studies of six cohorts for which the inclusion of retirees 
was deemed sufficient to adequately characterize silicosis morbidity 
risks well past employment (Hnizdo and Sluis-Cremer, 1991, Document ID 
1051; Steenland and Brown, 1995b, 0451; Miller et al., 1998, 0374; 
Buchanan et al., 2003, 0306; Chen et al., 2001, 0332; Chen et al., 
2005, 0985). Study populations included five mining cohorts and a 
Chinese pottery worker cohort. With the exception of a coal miner study 
(Buchanan et al., 2003, Document ID 0306), risk estimates reflected the 
risk that a worker will acquire an abnormal chest x-ray classified as 
ILO major category 1 or greater; the coal miner study evaluated the 
risk of acquiring an abnormal chest x-ray classified as major category 
2 or higher.
    For miners exposed to freshly cut respirable crystalline silica, 
OSHA estimates the risk of developing lesions consistent with an ILO 
classification of category 1 or greater to range from 120 to 773 cases 
per 1,000 workers exposed at the previous general industry PEL of 100 
[mu]g/m\3\ for 45 years; from 20 to 170 cases per 1,000 workers exposed 
at the final PEL of 50 [mu]g/m\3\; and from 5 to 40 cases per 1,000 
workers exposed at the new action level of 25 [mu]g/m\3\. From the coal 
miner study of Buchanan et al., (2003, Document ID 0306), OSHA 
estimates the risks of acquiring an abnormal chest x-ray classified as 
ILO category 2 or higher to be 301, 55, and 21 cases per 1,000 workers 
exposed for 45 years to 100, 50, and 25 [mu]g/m\3\, respectively. These 
estimates are within the range of risks obtained by OSHA from the other 
mining studies. At exposures at or above 250 [mu]g/m\3\ (equivalent to 
the previous construction and shipyard PELs) for 45 years, the risk of 
acquiring an abnormal chest x-ray approaches 100 percent. OSHA's risk 
estimates based on the pottery cohort are 60, 20, and 5 cases per 1,000

[[Page 16391]]

workers exposed for 45 years to 100, 50, and 25 [mu]g/m\3\, 
respectively, which is generally below the range of risks estimated 
from the other studies and may reflect a lower toxicity of quartz 
particles in that work environment due to the presence of 
aluminosilicates on the particle surfaces (see Section V.N, Comments 
and Responses Concerning Physico-chemical and Toxicological Properties 
of Respirable Crystalline Silica); they are still well over OSHA's 1 in 
a 1,000 workers benchmark for setting standards, however. According to 
Chen et al. (2005, Document ID 0985), adjustment of the exposure metric 
to reflect the unoccluded surface area of silica particles resulted in 
an exposure-response of pottery workers that was similar to the mining 
cohorts, indicating that the occluded surface reduced the toxic potency 
of the quartz particles. The finding of a reduced silicosis risk among 
pottery workers is consistent with other studies of clay and brick 
industries that have reported finding a lower prevalence of silicosis 
compared to that experienced in other industry sectors (Love et al., 
1999, Document ID 0369; Hessel, 2006, 1299; Miller and Soutar, 2007, 
1098) as well as a lower silicosis risk per unit of cumulative exposure 
(Love et al., 1999, Document ID 0369; Miller and Soutar, 2007, 1098).

D. Significance of Risk and Risk Reduction

    In this section, OSHA presents its final findings with respect to 
the significance of the risks summarized above and the potential of the 
proposed standard to reduce those risks. Findings related to mortality 
risk will be presented first, followed by silicosis morbidity risks.
1. Mortality Risks
    OSHA's Final Quantitative Risk Assessment described above presents 
risk estimates for four causes of excess mortality: Lung cancer, 
silicosis, non-malignant respiratory disease (including silicosis), and 
renal disease. Table VI-1 above presents OSHA's estimated excess 
lifetime risks (i.e., to age 85, following 45 years of occupational 
exposure) of these fatal diseases associated with various levels of 
respirable crystalline silica exposure allowed under the former PELs 
and the final PEL and action level promulgated herein. OSHA's mortality 
risk estimates represent ``excess'' risks in the sense that they 
reflect the risk of dying from disease over and above that of persons 
who are not occupationally exposed to respirable crystalline silica.
    Assuming a 45-year working life, as OSHA has done in significant 
risk determinations for previous standards, the Agency finds that the 
excess risk of disease mortality related to exposure to respirable 
crystalline silica at levels permitted by the previous OSHA standards 
is clearly significant. The Agency's estimate of such risk falls well 
above the level of risk the Supreme Court indicated a reasonable person 
would consider unacceptable (Benzene, 448 U.S. 607, 655). For lung 
cancer, OSHA estimates the range of risk at the previous general 
industry PEL to be between 11 and 54 deaths per 1,000 workers. The 
estimated risk for silicosis mortality is 11 deaths per 1,000 workers; 
however, the estimated lifetime risk for non-malignant respiratory 
disease (NMRD) mortality, including silicosis, is about 8-fold higher 
than that for silicosis alone, at 85 deaths per 1,000. This higher 
estimate for NMRD is better than the estimate for silicosis mortality 
at capturing the total respiratory disease burden associated with 
exposure to crystalline silica dust. The former captures deaths related 
to other non-malignant diseases, including chronic bronchitis and 
emphysema, for which there is strong evidence of a causal relationship 
with exposure to silica, and is also more likely to capture those 
deaths where silicosis was a contributing factor but where the cause of 
death was misclassified. Finally, there is an estimated lifetime risk 
of renal disease mortality of 39 deaths per 1,000. Exposure for 45 
years at levels of respirable crystalline silica in the range of the 
previous limits for construction and shipyards results in even higher 
risk estimates, as presented in Table VI-1. It should be noted that 
these risk estimates are not additive because some individuals may 
suffer from multiple diseases caused by exposure to silica.
    To further demonstrate significant risk, OSHA compares the risks at 
the former PELs and the revised PEL for respirable crystalline silica 
to risks found across a broad variety of occupations. OSHA also 
compares the lung cancer risk associated with the former PELs and 
revised PEL to the risks for other carcinogens OSHA regulates. The 
Agency has used similar occupational risk comparisons in the 
significant risk determinations for other substance-specific standards.
    Fatal injury rates for most U.S. industries and occupations may be 
obtained from data collected by the Department of Labor's Bureau of 
Labor Statistics (BLS). Table VI-3 shows annual fatality rates per 
1,000 employees for several industries for 2013, as well as projected 
fatalities per 1,000 employees assuming exposure to workplace hazards 
for 45 years based on these annual rates. While it is difficult to 
meaningfully compare aggregate industry fatality rates to the risks 
estimated in the quantitative risk assessment for respirable 
crystalline silica, which address one specific hazard (inhalation 
exposure to respirable crystalline silica) and several health outcomes 
(lung cancer, silicosis, NMRD, renal disease mortality), these rates 
provide a useful frame of reference for considering risk from 
inhalation exposure to crystalline silica. For example, OSHA's 
estimated range of 5-54 excess lung cancer deaths per 1,000 workers 
from regular occupational exposure to respirable crystalline silica in 
the range of 50-100 [mu]g/m\3\ is roughly comparable to, or higher 
than, the expected risk of fatal injuries over a working life in high-
risk occupations such as mining and construction (see Table VI-3). 
Regular exposures at higher levels, including the previous construction 
and shipyard PELs for respirable crystalline silica, are expected to 
cause substantially more deaths per 1,000 workers from lung cancer 
alone (ranging from 24 to 657 per 1,000) than result from occupational 
injuries in most private industry. At the final PEL of 50 [mu]g/
m3 respirable crystalline silica, the Agency's estimate of 
excess lung cancer mortality, from 5 to 23 deaths per 1,000 workers, is 
still 3- to 15-fold higher than private industry's average fatal injury 
rate, given the same employment time, and substantially exceeds those 
rates found in lower-risk industries such as finance and educational 
and health services. Adding in the mortality from silicosis, NMRD, and 
renal disease would make these comparisons even more stark.

[[Page 16392]]

[GRAPHIC] [TIFF OMITTED] TR25MR16.009

    Because there is little available information on the incidence of 
occupational cancer across all industries, risk from crystalline silica 
exposure cannot be compared with overall risk from other workplace 
carcinogens. However, OSHA's previous risk assessments provide 
estimates of risk from exposure to certain carcinogens. These risk 
assessments, as with the current assessment for respirable crystalline 
silica, were based on animal or human data of reasonable or high 
quality and used the best information then available. Table VI-4 shows 
the Agency's best estimates of cancer risk from 45 years of 
occupational exposure to several carcinogens, as published in the 
preambles to final rules promulgated since the Benzene decision in 
1980.

[[Page 16393]]

[GRAPHIC] [TIFF OMITTED] TR25MR16.010

    The estimated excess lung cancer mortality risks associated with 
respirable crystalline silica at the previous general industry PEL, 11-
54 deaths per 1,000 workers, are comparable to, and in some cases 
higher than, the estimated excess cancer risks for many other workplace 
carcinogens for which OSHA made a determination of significant risk 
(see Table VI-4, ``Selected OSHA Risk Estimates for Prior and Current 
PELs''). The estimated excess lung cancer risks associated with 
exposure to the previous construction and shipyard PELs are even 
higher. The estimated risk from lifetime occupational exposure to 
respirable crystalline silica at the final PEL of 50 [mu]g/m\3\ is 5-23 
excess lung cancer deaths per 1,000 workers, a range still higher than 
the risks from exposure to many other carcinogens regulated by OSHA.
    OSHA's risk assessment also shows that reduction of the PELs for 
respirable crystalline silica to the final level of 50 [mu]g/m\3\ will 
result in substantial reduction in risk, although quantitative 
estimates of that reduction vary depending on the statistical models 
used. Risk models that reflect attenuation of the risk with increasing 
exposure, such as those relating risk to a log transformation of 
cumulative exposure, will result in lower estimates of risk reduction 
compared to linear risk models. Thus, for lung cancer risks, the 
assessment based on the 10-cohort pooled analysis by Steenland et al. 
(2001, Document ID 0455; also 0469; 1312) suggests risk will be reduced 
by about 14 percent from the previous general industry PEL and by 28-41 
percent from the previous construction/shipyard PEL (based on the 
midpoint of the ranges of estimated risk derived from the three models 
used for the pooled cohort data). These risk reduction estimates, 
however, are much lower than those derived from the single cohort 
studies (Rice et al., 2001, Document ID 1118; Attfield and Costello, 
2004, 0543; Hughes et al., 2001, 1060; Miller and MacCalman 2009, 
1306). These single cohort studies suggest that reducing the previous 
PELs to the final PEL will reduce lung cancer risk by more than 50 
percent in general industry and by more than 80 percent in construction 
and shipyards.
    For silicosis mortality, OSHA's assessment indicates that risk will 
be reduced by 36 percent and by 58-68 percent as a result of reducing 
the previous general industry and construction/shipyard PELs, 
respectively. NMRD mortality risks will be reduced by 48 percent and by 
77-87 percent as a result of reducing the general industry and 
construction/shipyard PELs, respectively, to the new PEL. There is also 
a substantial reduction in renal disease mortality risks; an 18-percent 
reduction associated with reducing the previous general industry PEL 
and a 38-49 percent reduction associated with reducing the previous 
construction/shipyard PEL.
    Thus, OSHA believes that the final PEL of 50 [mu]g/m\3\ respirable 
crystalline silica will substantially reduce the risk of material 
health impairments associated with exposure to silica. However, even at 
this final PEL, as well as the action level of 25 [mu]g/m\3\, the risk 
posed to workers with 45 years of

[[Page 16394]]

regular exposure to respirable crystalline silica is greater than 1 per 
1,000 workers and is still clearly significant.
2. Silicosis Morbidity Risks
    OSHA's Final Quantitative Risk Assessment also characterizes the 
risk of developing silicosis, defined as developing lung fibrosis 
detected by chest x-ray. For 45 years of exposure at the previous 
general industry PEL of 100 [mu]g/m\3\, OSHA estimates that the risk of 
developing lung fibrosis consistent with an ILO category 1+ degree of 
small opacity profusion ranges from 60 to 773 cases per 1,000. For 
exposure at the previous construction and shipyard PELs, the risk 
approaches 100 percent. The wide range of risk estimates derived from 
the underlying studies relied on for the risk assessment may reflect 
differences in the relative toxicity of quartz particles in different 
workplaces; nevertheless, OSHA finds that each of these risk estimates 
clearly represents a significant risk of developing fibrotic lesions in 
the lung. Exposure to the final PEL of 50 [mu]g/m\3\ respirable 
crystalline silica for 45 years yields an estimated risk of between 20 
and 170 cases per 1,000 for developing fibrotic lesions consistent with 
an ILO category of 1+. These risk estimates indicate that the final PEL 
will result in a reduction in risk by about two-thirds or more, which 
the Agency finds is a substantial reduction of the risk of developing 
abnormal chest x-ray findings consistent with silicosis.
    One study of coal miners also permitted the agency to evaluate the 
risk of developing lung fibrosis consistent with an ILO category 2+ 
degree of profusion of small opacities (Buchanan et al., 2003, Document 
ID 0306). This level of profusion has been shown to be associated with 
a higher prevalence of lung function decrement and an increased rate of 
early mortality (Ng et al., 1987a, Document ID 1108; Begin et al., 
1988, 0296; Moore et al., 1988, 1099; Ng et al., 1992a, 0383; Infante-
Rivard, 1991, 1065). From this study, OSHA estimates that the risk 
associated with 45 years of exposure to the previous general industry 
100 [mu]g/m\3\ PEL is 301 cases per 1,000 workers, again a clearly 
significant risk. Exposure to the final PEL of 50 [mu]g/m\3\ respirable 
crystalline silica for 45 years yields an estimated risk of 55 cases 
per 1,000 for developing lesions consistent with an ILO category 2+ 
degree of small opacity profusion. This represents a reduction in risk 
of over 80 percent, again a clearly substantial reduction of the risk 
of developing radiologic silicosis consistent with ILO category 2+.
3. Sources of Uncertainty and Variability in OSHA's Risk Assessment
    Throughout the development of OSHA's risk assessment for silica-
related health effects, sources of uncertainty and variability have 
been identified by the Agency, peer reviewers, interagency reviewers, 
stakeholders, scientific experts, and the general public. This 
subsection reviews and summarizes several general areas of uncertainty 
and variability in OSHA's risk assessment. As used in this section, 
``uncertainty'' refers to lack of knowledge about factors affecting 
exposure or risk, and ``variability'' refers to heterogeneity, for 
example, across people, places, or time. For more detailed discussion 
and evaluation of sources of uncertainty in the risk assessment and a 
comprehensive review of comments received by OSHA on the risk 
assessment, (see discussions provided throughout the previous section, 
Section V, Health Effects).
    As shown in Table VI-1, OSHA's risk estimates for lung cancer are a 
range derived from a pooled analysis of 10 cohort studies (Steenland et 
al., 2001a, Document ID 0452; ToxaChemica, Inc., 2004, 0469), a study 
of granite workers (Attfield and Costello, 2004, Document ID 0543), a 
study of diatomaceous earth workers (Rice et al., 2001, Document ID 
1118), a multi-cohort study of industrial sand workers (Hughes et al., 
2001, Document ID 1060), and a study of coal miners exposed to 
respirable crystalline silica (Miller et al., 2007, Document ID 1305; 
Miller and MacCalman, 2009, 1306). Similarly, a variety of studies in 
several different working populations was used to derive risk estimates 
of silicosis mortality, silicosis morbidity, and renal disease 
mortality. The ranges of risks presented in Table VI-1 for silica 
mortality and the other health endpoints thus reflect silica exposure-
response across a variety of industries and worker populations, which 
may differ for reasons such as the processes in which silica exposure 
occurs and the various kinds of minerals that co-exist with crystalline 
silica in the dust particles (see discussion on variability in 
toxicological potency of crystalline silica later in this section). The 
ranges presented in Table VI-1 do not reflect statistical uncertainty 
(e.g., 95% confidence intervals) or model uncertainty (e.g., the slope 
of the exposure-response curve at exposures higher or lower than the 
exposures of the study population) but do reflect variability in the 
sources of data for the different studies.
    The risks presented in Table VI-1, however, do not reflect 
variability in the consistency, duration or frequency of workers' 
exposures. As discussed previously in this section, OSHA's final 
estimates of health risks represent risk associated with exposure to an 
8-hour time weighted average of 25, 50, 100, 250 and 500 [mu]g/m\3\ 
respirable crystalline silica. These levels represent the risks 
associated with continuous occupational exposure over a working 
lifetime of 45 years to the new action level, new PEL, previous general 
industry PEL, and the range in exposure (250-500 [mu]g/m\3\) that 
approximates the previous construction and shipyard PELs, respectively. 
OSHA estimates risks assuming exposure over a working life so that it 
can evaluate the significance of the risk associated with exposure at 
the previous PELs in a manner consistent with Section 6(b)(5) of the 
Act, which requires OSHA to set standards that substantially reduce 
these risks to the extent feasible even if workers are exposed over a 
full working lifetime. However, while the risk assessment is based on 
the assumed working life of 45 years, OSHA recognizes that risks 
associated with shorter-term or intermittent exposures at a given 
airborne concentration of silica will be less than the risk associated 
with continuous occupational exposure at the same concentration over a 
working lifetime. OSHA thus also uses alternatives to the 45-year full-
time exposure metric in its projections of the benefits of the final 
rule (Section VII of this preamble and the FEA) that reflect the 
reduction in silica-related disease that the Agency expects will result 
from implementation of the revised standard, using the various 
estimates of workers' typical exposure levels and patterns.
    The remainder of this discussion reviews several general areas of 
uncertainty and variability in OSHA's risk assessment that are not 
quantitatively reflected in the risk estimates shown in Table VI-1, but 
that provide important context for understanding these estimates, 
including differences in the degree of uncertainty among the estimates. 
These areas include exposure estimation error, dose-rate effects, model 
form uncertainty, variability in toxicological potency of crystalline 
silica, and additional sources of uncertainty specific to particular 
endpoints, (e.g., the small number of cases in the renal disease 
analysis), differing conclusions in the literature on silica as a 
causative factor in renal disease and lung cancer, and reporting error 
in silicosis mortality and morbidity. These different sources of 
uncertainty have varying effects that can lead either to under- or 
over-

[[Page 16395]]

estimation of risks. OSHA has taken these sources of uncertainty into 
account in concluding that the body of scientific literature supports 
the finding that there is significant risk at existing levels of 
exposure. The Agency is not required to support the finding that a 
``significant risk exists with anything approaching scientific 
certainty'' (Benzene, 448 U.S. at 656).
a. Exposure Estimation Error
    As discussed in Section V, OSHA identified exposure estimation 
error as a key source of uncertainty in most of the studies and thus 
the Agency's risk assessment. OSHA's contractor, ToxaChemica, Inc., 
commissioned Drs. Kyle Steenland and Scott Bartell to perform an 
uncertainty analysis to examine the effect of uncertainty due to 
exposure estimation error in the pooled studies (Steenland et al., 
2001a, Document ID 0452; Mannetje 2002b, 1089) on the lung cancer and 
silicosis mortality risk estimates (ToxaChemica, Inc., 2004, Document 
ID 0469). Drs. Steenland and Bartell addressed two main sources of 
error in the silica exposure estimates. The first arises from the 
assignment of individual workers' exposures based either on exposure 
measurements for a sample of workers in the same job or estimated 
exposure levels for specific jobs in the past when no measurements were 
available, via a job-exposure matrix (JEM) (Mannetje et al., 2002a, 
Document ID 1090). The second arises from the conversion of 
historically-available dust measurements, typically particle count 
concentrations, to gravimetric respirable silica concentrations. 
ToxaChemica, Inc. conducted an uncertainty analysis using the raw data 
from the IARC multi-centric study to address these sources of error 
(2004, Document ID 0469).
    To explore the potential effects of both kinds of uncertainty 
described above, ToxaChemica, Inc. (2004, Document ID 0469) used the 
distributions representing the error in job-specific exposure 
assignment and the error in converting exposure metrics to generate 50 
exposure simulations for each cohort. A study-specific coefficient and 
a pooled coefficient were fit for each new simulation. The results 
indicated that the only lung cancer cohort for which the mean of the 
exposure coefficients derived from the simulations differed 
substantially from the previously calculated exposure coefficient was 
the South African gold cohort (simulation mean of 0.181 vs. original 
coefficient of 0.582). This suggests that the results of exposure-
response analyses conducted using the South African cohort are 
sensitive to error in exposure estimates; therefore, there is greater 
uncertainty due to potential exposure estimation error in an exposure-
response model based on this cohort than is the case for the other nine 
cohorts in Steenland et al's analysis (or, put another way, the 
exposure estimation for the other nine cohorts was less sensitive to 
the effects of exposure measurement uncertainty).
    For the pooled analysis, the mean coefficient estimate from the 
simulations was 0.057, just slightly lower than the previous estimate 
of 0.060. Based on these results, OSHA concluded that random error in 
the underlying exposure estimates in the Steenland et al. (2001a, 
Document ID 0452) pooled cohort study of lung cancer is not likely to 
have substantially influenced the original findings.
    Following the same procedures described above for the lung cancer 
analysis, ToxaChemica, Inc. (2004, Document ID 0469) combined both 
sources of random measurement error in a Monte Carlo analysis of the 
silicosis mortality data from Mannetje et al. (2002b, Document ID 
1089). The silicosis mortality dataset appeared to be more sensitive to 
possible error in exposure measurement than the lung cancer dataset, 
for which the mean of the simulation coefficients was virtually 
identical to the original. To reflect this exposure measurement 
uncertainty, OSHA's final risk estimates derived from the pooled 
analysis (Mannetje et al., 2002b, Document ID 1089), incorporated 
ToxaChemica, Inc.'s simulated measurement error (2004, Document ID 
0469).
b. Uncertainty Related to Dose-Rate Effects
    OSHA received comments citing uncertainty in its risk assessment 
related to possible dose-rate effects in the silica exposure-response 
relationships, particularly for silicosis. For example, the ACC 
commented that extrapolating risks from the high mean exposure levels 
in the Park et al. 2002 cohort (Document ID 0405) to the much lower 
mean exposure levels relevant to OSHA's risk assessment contributes 
uncertainty to the analysis (Document ID 4209, pp. 84-85), because of 
the possibility that risk accrues differently at different exposure 
concentrations. The ACC thus argued that the risk associated with any 
particular level of cumulative exposure may be higher for exposure to a 
high concentration of respirable crystalline silica over a short period 
of time than for an equivalent cumulative exposure resulting from 
exposure to a low concentration of respirable crystalline silica over a 
long period of time (Document ID 4209, p. 58; 2307, Attachment A, pp. 
93-94). These and similar comments on dose-rate effects questioned 
OSHA's use of workers' cumulative exposure levels to estimate risk, as 
the cumulative exposure metric does not capture dose-rate effects. 
Thus, according to the ACC, if there are significant dose-rate effects 
in the exposure-response relationship for a disease or other health 
endpoint, use of the cumulative exposure metric could lead to error in 
risk estimates.
    The rationale for OSHA's reliance on a cumulative exposure metric 
to assess the risks of respirable crystalline silica is discussed in 
Section V. With respect to this issue of uncertainty related to dose-
response effects, OSHA finds limited evidence in the record to either 
support or refute the effects hypothesized by the ACC. As such, OSHA 
acknowledges some uncertainty. Furthermore, use of an alternative 
metric such as concentration would not provide assurance that 
uncertainties would be mitigated or reduced.
    Two studies discussed in OSHA's Review of Health Effects Literature 
and Preliminary QRA examined dose-rate effects on silicosis exposure-
response (Document ID 1711, pp. 342-344). Neither study found a dose-
rate effect relative to cumulative exposure at silica concentrations 
near the previous OSHA PEL (Document ID 1711, pp. 342-344). However, 
they did observe a dose-rate effect in instances where workers were 
exposed to crystalline silica concentrations far above the previous PEL 
(i.e., several-fold to orders of magnitude above 100 [mu]g/m\3\) 
(Buchanan et al., 2003, Document ID 0306; Hughes et al., 1998, 1059). 
The Hughes et al. (1998) study of diatomaceous earth workers found that 
the relationship between cumulative silica exposure and risk of 
silicosis was steeper for workers hired prior to 1950 and exposed to 
average concentrations above 500 [micro]g/m\3\ compared to workers 
hired after 1950 and exposed to lower average concentrations (Document 
ID 1059). Hughes et al. reported that subdivisions for workers with 
exposure to concentrations below 500 [mu]g/m\3\ were examined, but that 
no differences were observed across these groups (Document ID 1059, p. 
809). It is unclear whether sparse data at the low end of the 
concentration range contributed to this finding, as the authors did not 
provide detailed information on the distribution of exposures in the 
study population.
    The Buchanan et al. (2003) study of Scottish coal miners adjusted 
the cumulative exposure metric in the risk model to account for the 
effects of exposures to high concentrations where

[[Page 16396]]

the investigators found that, at concentrations above 2000 [mu]g/m\3\, 
the risk of silicosis was about three times higher than the risk 
associated with exposure to lower concentrations but at the same 
cumulative exposure (Document ID 0306, p. 162). Buchanan et al. noted 
that only 16 percent of exposure hours among the workers in the study 
occurred at levels below 10 [mu]g/m\3\ (Document ID 0306, p. 161), and 
cautioned that insufficient data are available to predict effects at 
very low concentrations where data are sparse (Document ID 0306, p. 
163). However, 56 percent of hours occurred at levels between 10 and 
100 [mu]g/m\3\. Detailed information on the hours worked at 
concentrations within this range was not provided.
    Based on its review of these studies, OSHA concluded that there is 
little evidence that a dose-rate effect exists at concentrations in the 
range of the previous PEL (100 [mu]g/m\3\) (Document ID 1711, p. 344). 
However, there remains some uncertainty related to dose-rate effects in 
the Agency's silicosis risk assessment. Even if a dose-rate effect 
exists only at concentrations far higher than the previous PEL, it is 
possible for the dose-rate effect to impact model form if not properly 
accounted for in study populations with high-concentration exposures. 
This is one reason that OSHA presents a range of risk estimates based 
on a variety of study populations exposed under different working 
conditions. For example, as OSHA noted in its Review of Health Effects 
Literature and Preliminary QRA (Document ID 1711, pp. 355-356), the 
Park et al. study is complemented by the Mannetje et al. multi-cohort 
silicosis mortality pooled study. Mannetje et al.'s study included 
several cohorts that had exposure concentrations in the range of 
interest for this rulemaking and also showed clear evidence of 
significant risk of silicosis mortality at the previous general 
industry and construction PELs (2002b, Document ID 1089). In addition, 
OSHA used the model from the Buchanan et al. study in its silicosis 
morbidity risk assessment to account for possible dose-rate effects at 
high average concentrations (Document ID 1711, pp. 335-342). OSHA notes 
that the risk estimates in the exposure range of interest (25-500 
[mu]g/m\3\) derived from the Buchanan et al. (2003) study were not 
appreciably different from those derived from the other studies of 
silicosis morbidity (see Table VI-1).
c. Model Form Uncertainty
    Another source of uncertainty in OSHA's risk analysis is 
uncertainty with respect to the form of the statistical models used to 
characterize the relationship between exposure level and risk of 
adverse health outcomes. As discussed in Section V, some commenters 
expressed concern that studies relied on by OSHA may not have 
considered all potential exposure-response relationships and might be 
unable to discern differences between monotonic and non-monotonic 
characteristics (e.g., Document ID 2307, Attachment A, p. 113-114).
    OSHA acknowledges that the possibility of error in selection of 
exposure-response model forms is a source of uncertainty in the silica 
risk assessment. To address this uncertainty, the Agency included 
studies in the risk assessment that explored a variety of model forms. 
For example, as discussed in Section V, the ToxaChemica reanalyses of 
the Mannetje et al. silicosis mortality dataset and the Steenland et 
al. lung cancer mortality data set examined several model forms 
including a five-knot restricted spline analysis, which is a highly 
flexible model form able to capture a variety of exposure-response 
shapes (Document ID 0469, p. 50). The ToxaChemica reanalysis addresses 
the issue of model form uncertainty by finding similar exposure-
response relationships regardless of the type of model used.
d. Uncertainty Related to Silica Exposure as a Risk Factor for Lung 
Cancer
    As discussed in Section V, OSHA has reviewed the best available 
evidence on the relationship between silica exposure and lung cancer 
mortality, and has concluded that the weight of evidence supports the 
finding that exposure to silica at the preceding and new PELs increases 
the risk of lung cancer. However, OSHA acknowledges that not every 
study in the literature on silica-related lung cancer reached the same 
conclusions. This variability is to be expected in epidemiology, as 
there are different cohorts, measurements, study designs, and 
analytical methods, among other factors. OSHA further acknowledges that 
there is uncertainty with respect to the magnitude of the risk of lung 
cancer from silica exposure. In the case of silica, the exposure-
response relationship with lung cancer may be easily obscured, as 
crystalline silica is a comparably weaker carcinogen (i.e., the 
increase in risk per unit exposure is smaller) than other well-studied, 
more potent carcinogens such as hexavalent chromium (Steenland et al., 
2001, Document ID 0452, p. 781) and tobacco smoke, a common co-exposure 
in silica-exposed populations.
    A study by Vacek et al. (2011) illustrates the uncertainties 
involved in evaluating risk of lung cancer from silica exposure. This 
study found no significant association between respirable silica 
exposure and lung cancer mortality in a cohort of Vermont granite 
workers (Document ID 1486, pp. 75-81). Some commenters criticized 
OSHA's preliminary risk assessment for rejecting the Vacek et al. 
(2011) study and instead relying upon the Attfield and Costello (2004, 
Document ID 0284) study of Vermont granite workers (Document ID 2307, 
Attachment A, pp. 36-47; 4209, pp. 34-36). As discussed in detail in 
Section V, OSHA reviewed the Vacek et al. study and all comments 
received by the Agency on this issue, and has decided not to reject the 
Attfield and Costello (2004) study in favor of the Vacek et al. (2011) 
study as a basis for risk assessment. OSHA acknowledges that 
comprehensive studies, such as those of Attfield and Costello (2004) 
and Vacek et al. (2011), in the Vermont granite industry have shown 
conflicting results with respect to lung cancer mortality (Document ID 
0284; 1486). Although OSHA believes that the Attfield and Costello 
(2004) study is the most appropriate Vermont granite study to use in 
its QRA, it also relied upon other studies, and that the risk estimates 
for lung cancer mortality based on those studies (i.e., Document ID 
0543, 1060, 1118, 1306) still provide substantial evidence that 
respirable crystalline silica poses a significant risk of lung cancer 
to exposed workers.
e. Uncertainty Related to Renal Disease
    As discussed in Section V, OSHA acknowledges that there are 
considerably less data for renal disease mortality than those for 
silicosis, lung cancer, and non-malignant respiratory disease (NMRD) 
mortality. Although the Agency believes the renal disease risk findings 
are based on credible data, the risk findings based on them are less 
robust than the findings for silicosis, lung cancer, and NMRD.
    Based upon its overall analysis of the literature, including the 
negative studies, OSHA has concluded that there is substantial evidence 
suggesting an association between exposure to crystalline silica and 
increased risks of renal disease. This conclusion is supported by a 
number of case reports and epidemiological studies that found 
statistically significant associations between occupational exposure to 
silica dust and chronic renal disease (Calvert et al., 1997, Document 
ID 0976), subclinical renal changes (Ng et al., 1992c, Document ID 
0386), end-stage renal disease morbidity (Steenland et

[[Page 16397]]

al., 1990, Document ID 1125), end-stage renal disease incidence 
(Steenland et al., 2001b, Document ID 0456), chronic renal disease 
mortality (Steenland et al., 2002a, 0448), and granulomatosis with 
polyangitis (Nuyts et al., 1995, Document ID 0397). However, as 
discussed in the Review of Health Effects Literature and Preliminary 
QRA, the studies reviewed by OSHA included a number of studies that did 
not show an association between crystalline silica and renal disease 
(Document ID 1711, pp. 211-229). Additional negative studies by Birk et 
al. (2009, Document ID 1468), and Mundt et al. (2011, Document ID 1478) 
were reviewed in the Supplemental Literature Review of the Review of 
Health Effects Literature and Preliminary QRA, which noted the short 
follow-up period as a limitation, which reduces the likelihood that an 
increased incidence of renal mortality would have been detected 
(Document ID 1711, Supplement, pp. 6-12). Comments submitted to OSHA by 
the ACC additionally cited several studies that did not show a 
statistically significant association between exposure to crystalline 
silica and renal disease mortality, including McDonald et al. (2005, 
Document ID 1092), Vacek et al. (2011, Document ID 2340), Davis et al. 
(1983, Document ID 0999), Koskela et al. (1987, Document ID 0363), 
Cherry et al. (2012, article included in Document ID 2340), Steenland 
et al. (2002b, Document ID 0454), Rosenman et al. (2000, Document ID 
1120), and Calvert et al. (2003, Document ID 0309) (Document ID 2307, 
Attachment A, pp. 140-145).
    As discussed in detail in Section V, OSHA concludes that the 
evidence supporting causality regarding renal risk outweighs the 
evidence casting doubt on that conclusion, but acknowledges this 
divergence in the renal disease literature as a source of uncertainty.
    OSHA estimated quantitative risks for renal disease mortality 
(Document ID 1711, pp. 314-316) using data from a pooled analysis of 
renal disease, conducted by Steenland et al. (2002a, Document ID 0448). 
The data set included 51 deaths from renal disease as an underlying 
cause, which the authors of the pooled study, Drs. Kyle Steenland and 
Scott Bartell, acknowledged to be insufficient to provide robust 
estimates of risk (Document ID 2307, Attachment A, p. 139, citing 0469, 
p. 27). OSHA agrees with Dr. Steenland and acknowledges, as it did in 
its Review of Health Effects Literature and Preliminary QRA (Document 
ID 1711, p. 357), that its quantitative risk estimates for renal 
disease mortality are less robust than those for the other health 
effects examined (i.e., lung cancer mortality, silicosis and NMRD 
mortality, and silicosis morbidity).
f. Uncertainty in Reporting and Diagnosis of Silicosis Mortality and 
Silicosis Morbidity
    OSHA's final quantitative risk assessment includes risk estimates 
for silicosis mortality and morbidity. Silicosis mortality is 
ascertained by analysis of death certificates for cause of death, and 
morbidity is ascertained by the presence of chest radiographic 
abnormalities consistent with silicosis among silica-exposed workers. 
Each of these kinds of studies are associated with uncertainties in 
case ascertainment and use of chest roentgenograms to detect lung 
scarring due to silicosis.
    For silicosis mortality, OSHA's analysis includes a pooled analysis 
of six epidemiological studies first published by Mannetje et al. 
(2002b, Document ID 1089) and re-analyzed by OSHA's contractor 
ToxaChemica (2004, Document ID 0469). OSHA finds that the estimates 
from Mannetje et al. and ToxaChemica's analyses are likely to 
understate the actual risk because silicosis is under-reported as a 
cause of death, as discussed in Sections VC.2.iv and V.E in the context 
of silicosis disease surveillance systems. To help address this 
uncertainty, OSHA's risk analysis also included an exposure-response 
analysis of diatomaceous earth (DE) workers (Park et al., 2002, 
Document ID 0405), which better captures the totality of silica-related 
respiratory disease than do the datasets analyzed by Mannetje et al. 
and ToxaChemica. Park et al.. quantified the relationship between 
cristobalite exposure and mortality caused by NMRD, which includes 
silicosis, pneumoconiosis, emphysema, and chronic bronchitis. Because 
NMRD captures much of the silicosis misclassification that results in 
underestimation of the disease and includes risks from other lung 
diseases associated with crystalline silica exposures, OSHA finds the 
risk estimates derived from the Park et al. study are important to 
include as part of OSHA's range of estimates of the risk of death from 
silica-related respiratory diseases, including silicosis. (Document ID 
1711, pp. 297-298). OSHA concludes that the range of silicosis and NMRD 
risks presented in the final risk assessment, based on both the 
ToxaChemica reanalysis of Mannetje et al.'s silicosis mortality data 
and Park et al.'s study of NMRD mortality, provide a credible range of 
estimates of mortality risk from silicosis and NMRD across a range of 
industrial workplaces. The upper end of this range, based on the Park 
et al. study, is less likely to underestimate risk as a result of 
under-reporting of silicosis mortality, but cannot be directly compared 
to risk estimates from studies that focused on cohorts of workers from 
different industries.
    OSHA's estimates of silicosis morbidity risks are based on studies 
of active and retired workers for which exposure histories could be 
constructed and chest x-ray films could be evaluated for signs of 
silicosis. There is evidence in the record that chest x-ray films are 
relatively insensitive to detecting lung fibrosis. Hnizdo et al. (1993, 
Document ID 1050) found chest x-ray films to have low sensitivity for 
detecting lung fibrosis related to silicosis, compared to pathological 
examination at autopsy. To address the low sensitivity of chest x-rays 
for detecting silicosis, Hnizdo et al. (1993, Document ID 1050) 
recommended that radiographs consistent with an ILO category of 0/1 or 
greater be considered indicative of silicosis among workers exposed to 
a high concentration of silica-containing dust. In like manner, to 
maintain high specificity, chest x-rays classified as category 1/0 or 
1/1 should be considered as a positive diagnosis of silicosis. Studies 
relied on in OSHA's risk assessment typically used an ILO category of 
1/0 or greater to identify cases of silicosis. According to Hnizdo et 
al., they are unlikely to include many false positives (diagnoses of 
silicosis where there is none), but may include false negatives 
(failure to identify cases of silicosis). Thus, the use of chest 
roentgenograms to ascertain silicosis cases in the morbidity studies 
relied on by OSHA in its risk assessment could lead to an 
underestimation of risk given the low sensitivity of chest 
roentgenograms for detecting silicosis.
g. Variability in Toxicological Potency of Crystalline Silica
    As discussed in Section V, the toxicological potency of crystalline 
silica is influenced by a number of physical and chemical factors that 
affect the biological activity of inhaled silica particles. The 
toxicological potency of crystalline silica is largely influenced by 
the presence of oxygen free radicals on the surfaces of respirable 
particles. These chemically-reactive oxygen species interact with 
cellular components in the lung to promote and sustain the inflammatory 
reaction responsible for the lung damage associated with exposure to 
crystalline silica. The reactivity of particle surfaces is greatest 
when crystalline silica has been freshly fractured by high-energy

[[Page 16398]]

work processes such as abrasive blasting, rock drilling, or sawing 
concrete materials. As particles age in the air, the surface reactivity 
decreases and exhibits lower toxicologic potency (Porter et al., 2002, 
Document ID 1114; Shoemaker et al., 1995, 0437; Vallyathan et al., 
1995, 1128). In addition, surface impurities have been shown to alter 
silica toxicity. For example, aluminum and aluminosilicate clay on 
silica particles has been shown to decrease toxicity (Castranova et 
al., 1997, Document ID 0978; Donaldson and Borm, 1998, 1004; Fubini, 
1998, 1016; Donaldson and Borm, 1998, Document ID 1004; Fubini, 1998, 
1016).
    In the preamble to the proposed standard, OSHA preliminarily 
concluded that although there is evidence that several environmental 
influences can modify surface activity to either enhance or diminish 
the toxicity of silica, the available information was insufficient to 
determine to what extent these influences may affect risk to workers in 
any particular workplace setting (Document 1711, p. 350). OSHA 
acknowledges that health risks are probably in the low end of the range 
for workers in the brick manufacturing industry, although the evidence 
still indicates that there is a significant risk at the previous 
general industry PEL for those workers. OSHA also acknowledges that 
there was a lack of evidence for a significant risk in the sorbent 
minerals industry due to the nature of crystalline silica present in 
those operations; as a result, it decided to exclude sorptive clay 
processing from this rule. Furthermore, Dudley and Morriss (2015) raise 
concerns about the whether the exposures reflected in the historical 
cohorts used in the risk assessment are sufficiently reflective of 
rapidly changing working conditions over the last 45 years.\11\ 
However, the risk estimates presented in Table VI-1 are based on 
studies from a variety of industries, such that the risk ranges 
presented are likely to include estimates appropriate to most working 
populations. Thus, in OSHA's view, its significant risk finding is well 
supported by the weight of best available evidence, notwithstanding 
uncertainties that may be present to varying degrees in the numerous 
studies relied upon and the even greater number of studies that the 
Agency considered.
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    \11\ Dudley, S. E. and Morriss, A. P. (2015), Will the 
Occupational Safety and Health Administration's Proposed Standards 
for Occupational Exposure to Respirable Crystalline Silica Reduce 
Workplace Risk?. Rish Analysis, 35: 1191-1196. doi:10.1111/
risa.12341
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4. OSHA's Response to Comments on Significant Risk of Material 
Impairment
    OSHA received several comments pertaining to the Agency's 
determination of a significant risk of material impairment of health 
posed to workers exposed for a working life to the previous PELs. 
Although many of these comments were supportive of OSHA's conclusions 
regarding the significance of risk, others were critical or suggested 
that OSHA has an obligation to further reduce the risk below that 
estimated to remain at the revised PEL.
    Referring to the previous PELs for respirable crystalline silica, 
the AFL-CIO commented that ``[w]orkers face a significant risk of harm 
from silica exposure at the current permissible exposure limits,'' and 
that ``[t]here is overwhelming evidence in the record that exposure to 
respirable crystalline silica poses a significant health risk to 
workers'' (Document ID 4204, pp. 10-11). The AFL-CIO noted that OSHA's 
mortality risk estimates well exceeded the benchmark of 1/1,000 excess 
risk over a working lifetime of exposure to the previous PELs, and also 
highlighted the risks of silicosis morbidity (Document ID 4204, p. 13). 
The AFL-CIO further pointed out that there is no cure for silicosis, 
and quoted oral testimony from workers at the informal public hearings 
demonstrating that ``[s]ilica-related diseases are still destroying 
workers' lives and livelihoods'' (Document ID 4204, p. 19).
    Both the UAW and the Building and Construction Trades Department 
(BCTD) concurred with the AFL-CIO that the previous PEL needs to be 
lowered to adequately protect workers. Referring to the previous PEL, 
the BCTD stated that ``[t]he record supports OSHA's determination that 
exposures at the current PEL present a significant risk'' (Document ID 
4223, p. 6). Although supportive of OSHA's proposed standard, the UAW 
also suggested the adoption of a PEL of 25 [micro]g/m\3\ or lower where 
feasible (Document ID 2282, Attachment 3, p.1), noting that a PEL set 
at this level ``will significantly reduce workers' exposure to deadly 
silica dust and prevent thousands of illnesses and deaths every year'' 
(Document ID 2282, Attachment 3, p. 25). Similarly, Charles Gordon, a 
retired occupational safety and health attorney, commented that the 
revised PEL ``leaves a remaining risk of 97 deaths per 1,000 workers 
from silicosis, lung cancer, and renal disease combined'' (Document ID 
4236, p. 2). Again, it should be noted that these risk estimates are 
not additive because some individuals may suffer from multiple diseases 
caused by exposure to silica. Instead, OSHA presents risk estimates for 
each health endpoint.
    As discussed above, OSHA acknowledges that there remains a 
significant risk of material impairment of health at the revised PEL; a 
further reduction in the PEL, however, is not currently technologically 
feasible (see Section VII, Summary of the Final Economic Analysis and 
Final Regulatory Flexibility Analysis, in which OSHA summarizes its 
assessment of the technological feasibility of the revised PEL). 
Despite this, the final PEL will provide a very substantial reduction 
in the risk of material impairment of health to silica-exposed workers, 
as described in the Benzene decision (Benzene, 448 U.S. at 642).
    In contrast to the foregoing comments from labor groups contending 
that OSHA would be setting the PEL too high if it made a final 
determination to lower the preceding PELs to 50 [micro]g/m\3\, critical 
comments came from industry groups including the American Chemistry 
Council (ACC), which disagreed with OSHA's determination of a 
significant risk of material impairment of health at the previous PELs. 
The ACC stated, ``OSHA's assessment of these risks is flawed, and its 
conclusions that the risks are significant at a PEL of 100 [micro]g/
m\3\ and would be substantially reduced by lowering the PEL to 50 
[micro]g/m\3\ are unsupported'' (Document ID 4209, p. 12). The ACC then 
asserted several ``fundamental shortcomings'' in OSHA's QRA on which 
OSHA based its significant risk determination (Document ID 4209, pp. 
16-17), including a variety of purported biases in the key studies on 
which OSHA relied. OSHA addresses the ACC's concerns in detail in 
Section V of this preamble dealing with the key studies relied upon by 
the Agency for each health endpoint, as well as separate sections 
addressing the issues of biases, causation, thresholds, the uncertainty 
analysis, and the life table and exposure assumptions used in the QRA. 
As more fully discussed in those sections, OSHA finds these concerns to 
be unpersuasive. As discussed in Section V, the scientific community 
and regulators in other advanced industrial societies agree on the need 
for a PEL of at most 50 [micro]g/m\3\ based on demonstrated health 
risks, and OSHA has used the best available evidence in the scientific 
literature to estimate quantitative risks of silica-related illnesses 
and thereby reach the same conclusion. OSHA's preliminary review of the 
health effects literature and OSHA's preliminary QRA were, further, 
examined by an independent, external peer review panel of

[[Page 16399]]

accomplished scientists, which lent credibility to the Agency's methods 
and findings and led to some adjustments in the analysis that 
strengthened OSHA's final risk assessment. There is, additionally, 
widespread support for the Agency's methods and conclusions in the 
rulemaking record. As such, OSHA is confident in its conclusion that 
there is a significant risk of material impairment of health to workers 
exposed to respirable crystalline silica at the levels of exposure 
permitted under the previous PELs and under this final standard, and 
finds no merit in broad assertions purporting to debunk this 
conclusion.
    In summary, as discussed throughout Section V and this final rule, 
OSHA concludes, based on the best available evidence in the scientific 
literature, that workers' exposure to respirable crystalline silica at 
the previous PELs results in a clearly significant risk of material 
impairment of health. The serious, and potentially fatal, health 
effects suffered by exposed workers include silicosis, lung cancer, 
NMRD, renal disease, and autoimmune effects. OSHA finds that the risk 
is substantially decreased, though still significant, at the new PEL of 
50 [micro]g/m\3\ and below, including at the new action level of 25 
[micro]g/m\3\. The Agency is constrained, however, from lowering the 
PEL further by its finding that a lower PEL would be infeasible in many 
operations across several industries. Given the significant risks faced 
by workers exposed to respirable crystalline silica under the 
previously-existing exposure limits, OSHA believes that it is 
imperative that it issue this final standard pursuant to its statutory 
mandate under the OSH Act.

VII. Summary of the Final Economic Analysis and Final Regulatory 
Flexibility Analysis

A. Introduction

    OSHA's Final Economic Analysis and Final Regulatory Flexibility 
Analysis (FEA) addresses issues related to the costs, benefits, 
technological and economic feasibility, and the economic impacts 
(including impacts on small entities) of this final respirable 
crystalline silica rule and evaluates regulatory alternatives to the 
final rule. Executive Orders 13563 and 12866 direct agencies to assess 
all costs and benefits of available regulatory alternatives and, if 
regulation is necessary, to select regulatory approaches that maximize 
net benefits (including potential economic, environmental, and public 
health and safety effects; distributive impacts; and equity). Executive 
Order 13563 emphasized the importance of quantifying both costs and 
benefits, of reducing costs, of harmonizing rules, and of promoting 
flexibility. The full FEA has been placed in OSHA rulemaking docket 
OSHA-2010-0034. This rule is an economically significant regulatory 
action under Sec. 3(f)(1) of Executive Order 12866 and has been 
reviewed by the Office of Information and Regulatory Affairs in the 
Office of Management and Budget, as required by executive order.
    The purpose of the FEA is to:
     Identify the establishments and industries potentially 
affected by the final rule;
     Estimate current exposures and the technologically 
feasible methods of controlling these exposures;
     Estimate the benefits resulting from employers coming into 
compliance with the final rule in terms of reductions in cases of 
silicosis, lung cancer, other forms of chronic obstructive pulmonary 
disease, and renal failure;
     Evaluate the costs and economic impacts that 
establishments in the regulated community will incur to achieve 
compliance with the final rule;
     Assess the economic feasibility of the final rule for 
affected industries; and
     Assess the impact of the final rule on small entities 
through a Final Regulatory Flexibility Analysis (FRFA), to include an 
evaluation of significant regulatory alternatives to the final rule 
that OSHA has considered.
Significant Changes to the FEA Between the Proposed Standards and the 
Final Standards
    OSHA changed the FEA for several reasons:
     Changes to the rule, summarized in Section I of this 
preamble and discussed in detail in the Summary and Explanation;
     Comments on the Preliminary Economic Analysis (PEA);
     Updates of economic data; and
     Recognition of errors in the PEA.
    OSHA revised its technological and economic analysis in response to 
these changes and to comments received on the NPRM. The FEA contains 
some costs that were not included in the PEA and updates data to use 
more recent data sources and, in some cases, revised methodologies. 
Detailed discussions of these changes are included in the relevant 
sections throughout the FEA.
    The FEA contains the following chapters:

Chapter I. Introduction
Chapter II. Market Failure and the Need for Regulation
Chapter III. Profile of Affected Industries
Chapter IV. Technological Feasibility
Chapter V. Costs of Compliance
Chapter VI. Economic Feasibility Analysis and Regulatory Flexibility 
Determination
Chapter VII. Benefits and Net Benefits
Chapter VIII. Regulatory Alternatives
Chapter IX. Final Regulatory Flexibility Analysis
Chapter X. Environmental Impacts

    Table VII-1 provides a summary of OSHA's best estimate of the costs 
and estimated benefits of the final rule using a discount rate of 3 
percent. As shown, the final rule is estimated to prevent 642 
fatalities and 918 silica-related illnesses annually once it is fully 
effective, and the estimated cost of the rule is $1,030 million 
annually. Also as shown in Table VII-1, the discounted monetized 
benefits of the final rule are estimated to be $8.7 billion annually, 
and the final rule is estimated to generate net benefits of $7.7 
billion annually. Table VII-1 also presents the estimated costs and 
estimated benefits of the final rule using a discount rate of 7 
percent.

[[Page 16400]]

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    The remainder of this section (Section VII) of the preamble is 
organized as follows:

    B. Market Failure and the Need for Regulation
    C. Profile of Affected Industries
    D. Technological Feasibility
    E. Costs of Compliance
    F. Economic Feasibility Analysis and Regulatory Flexibility 
Determination
    G. Benefits and Net Benefits
    H. Regulatory Alternatives
    I. Final Regulatory Flexibility Analysis.

B. Market Failure and the Need for Regulation

    Employees in work environments addressed by the final silica rule 
are exposed to a variety of significant hazards that can and do cause 
serious injury and death. As described in Chapter II of the FEA in 
support of the final rule, OSHA concludes there is a failure of private 
markets to protect workers from exposure to unnecessarily high levels 
of respirable crystalline silica and that private markets, as well as 
information dissemination programs, workers' compensation systems, and

[[Page 16401]]

tort liability options, each may fail to protect workers from silica 
exposure, resulting in the need for a more protective OSHA silica rule.
    After carefully weighing the various potential advantages and 
disadvantages of using a regulatory approach to improve upon the 
current situation, OSHA concludes that, in the case of silica exposure, 
the final mandatory standards represent the best choice for reducing 
the risks to employees. In addition, rulemaking is necessary in this 
case in order to replace older existing standards with updated, clear, 
and consistent health standards.

C. Profile of Affected Industries

Introduction
    Chapter III of the FEA presents profile data for industries 
potentially affected by the final silica rule. The discussion below 
summarizes the findings in that chapter. As a first step, OSHA 
identifies the North American Industrial Classification System (NAICS) 
industries, both in general industry and maritime and in the 
construction sector, with potential worker exposure to silica. Next, 
OSHA provides summary statistics for the affected industries, including 
the number of affected entities and establishments, the number of 
workers whose exposure to silica could result in disease or death 
(``at-risk workers''), and the average revenue for affected entities 
and establishments.\12\ Finally, OSHA presents silica exposure profiles 
for at-risk workers. These data are presented by sector and job 
category. Summary data are also provided for the number of workers in 
each affected industry who are currently exposed above the final silica 
PEL of 50 [mu]g/m\3\, as well as above an alternative PEL of 100 [mu]g/
m\3\ for economic analysis purposes.
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    \12\ The Census Bureau defines an establishment as a single 
physical location at which business is conducted or services or 
industrial operations are performed. The Census Bureau defines a 
business firm or entity as a business organization consisting of one 
or more domestic establishments in the same state and industry that 
were specified under common ownership or control. The firm and the 
establishment are the same for single-establishment firms. For each 
multi-establishment firm, establishments in the same industry within 
a state will be counted as one firm; the firm employment and annual 
payroll are summed from the associated establishments. (US Census 
Bureau, Statistics of US Businesses, Definitions. 2015, http://www.census.gov/econ/susb/definitions.html?cssp=SERP).
---------------------------------------------------------------------------

    The methodological basis for the industry and at-risk worker data 
presented in this chapter comes from the PEA, the Eastern Research 
Group (ERG) analysis supporting the PEA (2007a, 2007b, 2008a, and 
2008b),\13\ and ERG's analytic support in preparing the FEA. The data 
used in this chapter come from the rulemaking record (Docket OSHA-2010-
0034), the technological feasibility analyses presented in Chapter IV 
of the FEA, and from OSHA (2016), which updated its earlier 
spreadsheets to reflect the most recent industry data available. To do 
so, ERG first matched the BLS Occupational Employment Statistics (OES) 
survey occupational titles with the at-risk job categories, by NAICS 
industry. ERG then calculated the percentages of production employment 
represented by each at-risk job title within industry (see OSHA, 2016 
for details on the calculation of employment percentages and the 
mapping of at-risk job categorizations into OES occupations).\14\ ERG's 
expertise for identifying the appropriate OES occupations and 
calculating the employment percentages enabled OSHA to estimate the 
number of employees in the at-risk job categories by NAICS industry 
(Id.).
---------------------------------------------------------------------------

    \13\ Document ID, 1709, 1608, 1431, and 1365, respectively.
    \14\ Production employment includes workers in building and 
grounds maintenance; forestry, fishing, and farming; installation 
and maintenance; construction; production; and material handling 
occupations.
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    In the NPRM and PEA, OSHA invited the public to submit additional 
information and data that might help improve the accuracy and 
usefulness of the preliminary industry profile; the profile presented 
here and in Chapter III of the FEA reflects public comment.
Selection of NAICS Industries for Analysis
    The technological feasibility analyses presented in Chapter IV of 
the FEA identify the general industry and maritime sectors and the 
construction activities potentially affected by the final silica 
standard.
General Industry and Maritime
    Employees engaged in various activities in general industry and 
maritime routinely encounter crystalline silica as a molding material, 
as an inert mineral additive, as a component of fluids used to 
stimulate well production of oil or natural gas, as a refractory 
material, as a sandblasting abrasive, or as a natural component of the 
base materials with which they work. Some industries use various forms 
of silica for multiple purposes. As a result, employers are faced with 
the challenge of limiting worker exposure to silica in dozens of job 
categories throughout the general industry and maritime sectors.
    Job categories in general industry and maritime were selected for 
analysis based on data from the technical industrial hygiene 
literature, evidence from OSHA Special Emphasis Program (SEP) results, 
and, in several cases, information from ERG site visit reports and 
public comment submitted into the record. These data sources provided 
evidence of silica exposures in numerous sectors. While the available 
data are not entirely comprehensive, OSHA believes that silica 
exposures in other sectors are quite limited.
    The industry subsectors in the overall general industry and 
maritime application groups that OSHA identified as being potentially 
affected by the final silica standard are as follows:

 Asphalt Paving Products
 Asphalt Roofing Materials
 Hydraulic Fracturing
 Industries with Captive Foundries
 Concrete Products
 Cut Stone
 Dental Equipment and Supplies
 Dental Laboratories
 Flat Glass
 Iron Foundries
 Jewelry
 Mineral Processing
 Mineral Wool
 Nonferrous Sand Casting Foundries
 Non-Sand Casting Foundries
 Other Ferrous Sand Casting Foundries
 Other Glass Products
 Paint and Coatings
 Porcelain Enameling
 Pottery
 Railroads
 Ready-Mix Concrete
 Refractories
 Refractory Repair
 Shipyards
 Structural Clay

    In some cases, affected industries presented in the technological 
feasibility analysis have been disaggregated to facilitate the cost and 
economic impact analysis. In particular, flat glass, mineral wool, and 
other glass products are subsectors of the glass industry described in 
Chapter IV, Section IV-9, of the FEA, and captive foundries,\15\ iron 
foundries, nonferrous sand casting foundries, non-sand cast foundries, 
and other ferrous sand casting foundries are subsectors of the

[[Page 16402]]

overall foundries industry presented in Chapter IV, Section IV-8, of 
the FEA.
---------------------------------------------------------------------------

    \15\ Captive foundries include establishments in other 
industries with foundry processes incidental to the primary products 
manufactured. ERG (2008b, Document ID 1365) provides a discussion of 
the methodological issues involved in estimating the number of 
captive foundries and in identifying the industries in which they 
are found. Since the 2008 ERG report, through comment in the public 
record and the public hearings, OSHA has gained additional 
information on the presence of captive foundries throughout general 
industry.
---------------------------------------------------------------------------

    As described in ERG (2008b, Document ID 1365) and updated in OSHA 
(2016), OSHA identified the six-digit NAICS codes for these subsectors 
to develop a list of industries potentially affected by the final 
silica standard. Table VII-2 presents the sectors listed above with 
their corresponding six-digit NAICS industries. The NAICS codes and 
associated industry definitions in the FEA are consistent with the 2012 
NAICS edition.
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Construction
    The construction sector is an integral part of the nation's 
economy, accounting for approximately 4.5 percent of total private 
sector employment. Establishments in this industry are involved in a 
wide variety of activities, including land development and subdivision, 
homebuilding, construction of nonresidential buildings and other 
structures, heavy construction work (including roadways and bridges), 
and a myriad of special trades such as plumbing, roofing, electrical, 
excavation, and demolition work.
    Construction activities were selected for analysis based on 
historical data of recorded samples of construction worker exposures 
from the OSHA Integrated Management Information System (IMIS) and the 
National Institute for Occupational Safety and Health (NIOSH). In 
addition, OSHA reviewed the industrial hygiene literature across the 
full range of construction activities and focused on dusty operations 
where silica sand was most likely to be fractured or abraded by work 
operations. These physical processes have been found to cause the 
silica exposures that pose the greatest risk of silicosis for workers.
    The construction activities, by equipment or task, that OSHA 
identified as being potentially affected by the final silica standard 
are as follows:
 Earth drilling
 Heavy Equipment Operators and Ground Crew Laborers--I 
(Abrading or fracturing silica containing materials or demolishing 
concrete or masonry structures)
 Heavy Equipment Operators and Ground Crew Laborers--II 
(Grading and Excavating)
 Hole Drillers Using Handheld or Stand-Mounted Drills
 Jackhammers and Other Powered Handheld Chipping Tools
 Masonry and Concrete Cutters Using Portable Saws--I (Handheld 
power saws)
 Masonry and Concrete Cutters Using Portable Saws--II (Handheld 
power saws for cutting fiber-cement board)
 Masonry and Concrete Cutters Using Portable Saws--III (Walk-
behind saws)
 Masonry and Concrete Cutters Using Portable Saws--IV (Drivable 
or ride-on concrete saws)
 Masonry and Concrete Cutters Using Portable Saws--V (Rig-
mounted core saws or drills)
 Masonry Cutters Using Stationary Saws
 Millers Using Portable or Mobile Machines--I (Walk-behind 
milling machines and floor grinders)
 Millers Using Portable or Mobile Machines--II (Small drivable 
milling machine (less than half-lane))
 Millers Using Portable or Mobile Machines--III (Milling 
machines (half-lane and larger with cuts of any depth on asphalt only 
and for cuts of four inches in depth or less on any other substrate))
 Rock and Concrete Drillers--I (Vehicle-mounted drilling rigs 
for rock and concrete)
 Rock and Concrete Drillers--II (Dowel drilling rigs for 
concrete)
 Mobile Crushing Machine Operators and Tenders
 Tuckpointers and Grinders--I (Handheld grinders for mortar 
removal (e.g., tuckpointing))
 Tuckpointers and Grinders--II (Handheld grinders for uses 
other than mortar removal)
    As shown in OSHA (2016) and in Chapter IV of the FEA, these 
construction activities occur in the following industries and 
governmental bodies, accompanied by their four-digit NAICS codes: \16\ 
\17\
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    \16\ ERG and OSHA used the four-digit NAICS codes for the 
construction sector both because the BLS's Occupational Employment 
Statistics survey only provides data at this level of detail ad 
because, unlike the case in general industry and maritime, job 
categories in the construction sector are task-specific, not 
industry-specific. Furthermore, as far as economic impacts are 
concerned, IRS data on profitability are reported only at the four-
digit NAICS code level of detail.
    \17\ Some public employees in state and local governments are 
exposed to elevated levels of respirable crystalline silica. These 
exposures are included in the construction sector because they are 
the result of construction activities.
---------------------------------------------------------------------------

 2361 Residential Building Construction
 2362 Nonresidential Building Construction

[[Page 16407]]

 2371 Utility System Construction
 2372 Land Subdivision
 2373 Highway, Street, and Bridge Construction
 2379 Other Heavy and Civil Engineering Construction
 2381 Foundation, Structure, and Building Exterior Contractors
 2382 Building Equipment Contractors
 2383 Building Finishing Contractors
 2389 Other Specialty Trade Contractors
 2211 Electric Utilities
 9992 State Government
 9993 Local Government
Characteristics of Affected Industries
    Table VII-3 provides an overview of the industries and estimated 
number of workers affected by the final rule. Included in Table VII-3 
are summary statistics for each of the affected industries, subtotals 
for construction and for general industry and maritime, and grand 
totals for all affected industries combined.
    The first five columns in Table VII-3 identify the NAICS code for 
each industry in which workers are routinely exposed to respirable 
crystalline silica and the name or title of the industry, followed by 
the total number of entities, establishments, and employees for that 
industry. Note that, while the industries are characterized by such 
exposure, not every entity, establishment, and employee in these 
affected industries engage in activities involving silica exposure.
    The next three columns in Table VII-3 show, for each affected 
industry, the number of entities and establishments in which workers 
are actually exposed to silica and the total number of workers exposed 
to silica. The number of affected establishments was set equal to the 
total number of establishments in an industry (based on Census data) 
unless the number of affected establishments would exceed the number of 
affected employees in the industry. In that case, the number of 
affected establishments in the industry was set equal to the number of 
affected employees, and the number of affected entities in the industry 
was reduced so as to maintain the same ratio of entities to 
establishments in the industry.\18\
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    \18\ OSHA determined that removing this assumption would have a 
negligible impact on total costs and would reduce the cost and 
economic impact on the average affected establishment or entity.
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    As shown in Table VII-3, OSHA estimates that a total of 652,600 
entities (586,800 in construction; 65,900 in general industry and 
maritime), 675,800 establishments (600,700 in construction; 75,100 in 
general industry and maritime), and 2.3 million workers (2.0 million in 
construction; 0.3 million in general industry and maritime) would be 
affected by the final silica rule. Note that only 67 percent of the 
entities and establishments, and about 21 percent of the workers in 
affected industries,

[[Page 16419]]

actually engage in activities involving silica exposure.\19\
---------------------------------------------------------------------------

    \19\ It should be emphasized that these percentages vary 
significantly depending on the industry sector and, within an 
industry sector, depending on the NAICS industry. For example, about 
35 percent of the workers in construction, but only 6 percent of 
workers in general industry, actually engage in activities involving 
silica exposure. As an example within construction, about 35 percent 
of workers in highway, street, and bridge construction, but only 3 
percent of workers in state and local governments, actually engage 
in activities involving silica exposure.
---------------------------------------------------------------------------

    The ninth column in Table VII-3, with data only for construction, 
shows for each affected NAICS construction industry the number of full-
time-equivalent (FTE) affected workers that corresponds to the total 
number of affected construction workers in the previous column.\20\ 
This distinction is necessary because affected construction workers may 
spend large amounts of time working on tasks with no risk of silica 
exposure. As shown in Table VII-3, the 2.0 million affected workers in 
construction converts to approximately 387,700 FTE affected workers. In 
contrast, OSHA based its analysis of the affected workers in general 
industry and maritime on the assumption that they were engaged full 
time in activities with some silica exposure.
---------------------------------------------------------------------------

    \20\ FTE affected workers becomes a relevant variable in the 
estimation of control costs in the construction industry. The reason 
is that, consistent with the costing methodology, control costs 
depend only on how many worker-days there are in which exposures are 
above the PEL. These are the worker-days in which controls are 
required. For the derivation of FTEs, see Tables IV-8 and IV-22 and 
the associated text in ERG (2007a, Document ID 1709).
---------------------------------------------------------------------------

    The last three columns in Table VII-3 show combined total revenues 
for all entities (not just affected entities) in each affected 
industry, and the average revenue per entity and per establishment in 
each affected industry. Because OSHA did not have data to distinguish 
revenues for affected entities and establishments in any industry, 
average revenue per entity and average revenue per affected entity (as 
well as average revenue per establishment and average revenue per 
affected establishment) are estimated to be equal in value.
Silica Exposure Profile of At-Risk Workers
    The technological feasibility analyses presented in Chapter IV of 
the FEA contain data and discussion of worker exposures to silica 
throughout industry. Exposure profiles, by job category, were developed 
from individual exposure measurements that were judged to be 
substantive and to contain sufficient accompanying description to allow 
interpretation of the circumstance of each measurement. The resulting 
exposure profiles show the job categories with current overexposures to 
silica and, thus, the workers for whom silica controls would be 
implemented under the final rule.
    Chapter IV of the FEA includes a section with a detailed 
description of the methods used to develop the exposure profile and to 
assess the technological feasibility of the final standard. The final 
exposure profiles take the exposure data that were used for the same 
purpose in OSHA's PEA and build upon them, using new data in the 
rulemaking record. The sampling data that were used to identify the 
affected industries and to develop the exposure profiles presented in 
the PEA were obtained from a comprehensive review of the following 
sources of information: OSHA compliance inspections conducted before 
2011, OSHA contractor (ERG) site visits performed for this rulemaking, 
NIOSH site visits, NIOSH Health Hazard Evaluation reports (HHEs), 
published literature, submissions by individual companies or 
associations and, in a few cases, data from analogous operations 
(Document ID 1720, pp. IV-2-IV-3). The exposure profiles presented in 
the PEA were updated for the FEA using exposure measurements from the 
OSHA Information System (OIS) that were taken during compliance 
inspections conducted between 2011 and 2014 (Document ID 3958). In 
addition, exposure data submitted to the record by rulemaking 
participants were used to update the exposure profiles. The criteria 
used for determining whether to include exposure data in the exposure 
profiles are described in Section IV-2--Methodology in Chapter IV of 
the FEA. As explained there, some of the original data are no longer 
used in the exposure profiles based on those selection or screening 
criteria. OSHA considers the exposure data relied upon for its analysis 
to be the best available evidence of baseline silica exposure 
conditions.
    Table VII-4 summarizes, from the exposure profiles, the total 
number of workers at risk from silica exposure at any level, and the 
distribution of 8-hour TWA respirable crystalline silica exposures by 
job category for general industry and maritime sectors and for 
construction activities. Exposures are grouped into the following 
ranges: Less than 25 [mu]g/m\3\; >= 25 [mu]g/m\3\ and <= 50 [mu]g/m\3\; 
> 50 [mu]g/m\3\ and <= 100 [mu]g/m\3\; > 100 [mu]g/m\3\ and <= 250 
[mu]g/m\3\; and greater than 250 [mu]g/m\3\. These frequencies 
represent the percentages of production employees in each job category 
and sector currently exposed at levels within the indicated range.
    Table VII-5 presents data by NAICS code--for each affected general, 
maritime, and construction industry--on the estimated number of workers 
currently at risk from silica exposure, as well as the estimated number 
of workers at risk of silica exposure at or above 25 [mu]g/m\3\, above 
50 [mu]g/m\3\, and above 100 [mu]g/m\3\. As shown, an estimated 
1,249,250 workers (1,097,000 in construction; 152,300 in general 
industry and maritime) currently have silica exposures at or above the 
new action level of 25 [mu]g/m\3\; an estimated 948,100 workers 
(847,700 in construction; 100,400 in general industry and maritime) 
currently have silica exposures above the new PEL of 50 [mu]g/m\3\; and 
an estimated 578,000 workers (519,200 in construction; 58,800 in 
general industry and maritime) currently have silica exposures above 
100 [mu]g/m\3\--an alternative PEL investigated by OSHA for economic 
analysis purposes.
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BILLING CODE 4510-26-C

D. Technological Feasibility

    In Chapter IV of OSHA's FEA, OSHA assesses the technological 
feasibility of the standard in all affected industry sectors and 
application groups. The analysis presented in this chapter is organized 
by industry sectors in general industry and maritime and by application 
groups in the construction industry. Employee exposures were analyzed 
at the operation, job category or task/activity level to the extent 
that the necessary data were available.

[[Page 16433]]

OSHA collected exposure data to characterize current (baseline) 
exposures and to identify the tasks, operations, and job categories for 
which employers will need to either improve their process controls or 
implement additional controls to reduce respirable crystalline silica 
exposures to 50 [micro]g/m\3\ or below. In the few instances where 
there were insufficient exposure data, OSHA used analogous operations 
to characterize these operations.
    The technological feasibility analysis informed OSHA's selection of 
the rule's permissible exposure limit (PEL) of 50 [micro]g/m\3\ 
respirable crystalline silica, consistent with the requirements of the 
Occupational Safety and Health Act (``OSH Act''), 29 U.S.C. 651 et seq. 
Section 6(b)(5) of the OSH Act requires that OSHA ``set the standard 
which most adequately assures, to the extent feasible, on the basis of 
the best available evidence, that no employee will suffer material 
impairment of health or functional capacity'' (29 U.S.C. 655(b)(5)). In 
fulfilling this statutory directive, OSHA is guided by the legal 
standard expressed by the Court of Appeals for the D.C. Circuit for 
demonstrating the technological feasibility of reducing occupational 
exposure to a hazardous substance:

    OSHA must prove a reasonable possibility that the typical firm 
will be able to develop and install engineering and work practice 
controls that can meet the PEL in most of its operations. . . . The 
effect of such proof is to establish a presumption that industry can 
meet the PEL without relying on respirators. . . . Insufficient 
proof of technological feasibility for a few isolated operations 
within an industry, or even OSHA's concession that respirators will 
be necessary in a few such operations, will not undermine this 
general presumption in favor of feasibility. Rather, in such 
operations firms will remain responsible for installing engineering 
and work practice controls to the extent feasible, and for using 
them to reduce . . . exposure as far as these controls can do so 
(United Steelworkers of Am, AFL-CIO-CLC v. Marshall, 647 F.2d 1189, 
1272 (D.C. Cir. 1980)).

    Additionally, the D.C. Circuit explained that ``[f]easibility of 
compliance turns on whether exposure levels at or below [the PEL] can 
be met in most operations most of the time . . . '' (Am. Iron & Steel 
Inst. v. OSHA, 939 F.2d 975, 990 (D.C. Cir. 1991)); (see Section II, 
Pertinent Legal Authority).
    Consistent with the legal standard described above, Chapter IV of 
the FEA, which can be found at www.regulations.gov (docket OSHA-2010-
0034), describes OSHA's examination of the technological feasibility of 
this rule on occupational exposure to respirable crystalline silica. 
The chapter provides a description of the methodology and data used by 
OSHA to analyze the technological feasibility of the standard, as well 
as a discussion of the accuracy and reliability of current methods used 
for the sampling and analysis of respirable crystalline silica. Chapter 
IV contains OSHA's analyses, for 21 general industry sectors, 1 
maritime sector, and 12 construction industry application groups, of 
the technological feasibility of meeting the rule's requirements for 
reducing exposures to silica. For each sector and application group, 
OSHA addresses the extent to which the evidence in the record indicates 
that engineering and work practice controls can reduce respirable 
crystalline silica exposures to the PEL or below and maintain them at 
that level. These individual technological feasibility analyses form 
the basis for OSHA's overall finding that employees' exposures can be 
reduced to the rule's PEL or below in most of the affected sectors' 
operations. Throughout Chapter IV, OSHA describes and responds to 
issues raised in the comments and testimony it received from interested 
parties during the comment periods and public hearing OSHA held on the 
proposed rule. The material below summarizes the detailed discussion 
and presentation of OSHA's findings contained in Chapter IV of the FEA.
1. Methodology
    As noted above, OSHA's technological feasibility analysis for this 
rule largely involved describing engineering and work practice controls 
that OSHA concludes can be expected to control respirable crystalline 
silica exposures to the PEL or below. For this portion of the analysis, 
OSHA relied on information and exposure measurements from many 
different sources, including OSHA's inspection database (OSHA 
Information System (OIS)), OSHA inspection reports, National Institute 
of Occupational Safety and Health (NIOSH) reports, site visits by NIOSH 
and OSHA's contractor, Eastern Research Group, Inc. (ERG), and 
materials from other federal agencies, state agencies, labor 
organizations, industry associations, and other groups. In addition, 
OSHA reviewed studies from the published literature that evaluated the 
effectiveness of engineering controls and work practices in order to 
estimate the reductions from current, baseline exposures to silica that 
can be achieved through wider or improved implementation of such 
controls. Finally, OSHA considered the extensive testimony and numerous 
comments regarding the feasibility of implementing engineering and work 
practice controls, including circumstances that preclude the use of 
controls in certain situations. In total, OSHA's feasibility analysis 
is based on hundreds of sources of information in the record, 
constituting one of the largest databases of information OSHA has used 
to evaluate the feasibility of a health standard.
    The technological feasibility chapter of the FEA describes the 
industry sectors and application groups affected by the rule, and 
identifies the sources of exposure to respirable crystalline silica for 
each affected job category or task. The technological feasibility 
analysis subdivides the general industry and maritime workplaces into 
24 industry sectors.\21\ General industry sectors are identified 
primarily based on the type of product manufactured (e.g., concrete 
products, pottery, glass) or type of process used (e.g., foundries, 
mineral processing, refractory repair). Where sufficiently detailed 
information was available, the Agency further divided general industry 
sectors into specific job categories on the basis of common factors 
such as materials, work processes, equipment, and available exposure 
control methods. OSHA notes that these job categories are intended to 
represent job functions; actual job titles and responsibilities might 
differ depending on the facility or industry practice.
---------------------------------------------------------------------------

    \21\ OSHA's technological feasibility analysis in the FEA is 
divided into 22 sections, one for each of the general industry and 
maritime sectors. However, separate technological feasibility 
findings are made for three different foundry sectors (ferrous, 
nonferrous, and non-sand casting foundries), making a total of 24 
sectors for which separate analyses and findings are made (see Table 
VII-8).
---------------------------------------------------------------------------

    For the construction industry, OSHA identified application groups 
based on construction activities, tasks, or equipment that are commonly 
recognized to create silica exposures; these tasks involve the use of 
power tools (e.g., saws, drills, jackhammers) or larger equipment that 
generates silica-containing dust (e.g., milling machines, rock and 
concrete crushers, heavy equipment used in demolition or earthmoving). 
The technological feasibility analysis for the construction industry 
addresses 12 different application groups, defined by common 
construction tasks or activities. OSHA organized construction workers 
by application groups, rather than by industry sector or job titles, 
because construction workers often perform multiple activities and job 
titles do not always coincide with the sources of exposure; likewise, 
the same equipment,

[[Page 16434]]

tool or task may be called by different names throughout construction 
and its various subspecialties. By organizing construction activities 
this way, OSHA was able to create exposure profiles for employees who 
perform the same activities in any segment of the construction 
industry.
    OSHA developed exposure profiles for each sector and application 
group in order to characterize the baseline exposures and conditions 
for each operation or task (see sections 4 and 5 of Chapter IV of the 
FEA). The sample results included in the exposure profiles presented in 
the Preliminary Economic Analysis (PEA) were obtained primarily from 
OSHA compliance inspection reports and from NIOSH Health Hazard 
Evaluation and control technology assessments. Samples were also 
obtained from state plan case files, contractor site visits, published 
literature and other sources. To ensure the exposure profiles were 
based on the best available data, the exposure profiles were updated by 
removing samples collected prior to 1990 (n = 290), leaving 2,512 
samples from exposure profiles presented in the PEA from 1990 through 
2007. More recent samples submitted by commenters during the rulemaking 
(n = 153), primarily from 2009 through 2014, and samples obtained from 
the OIS database (n = 699) from OSHA compliance inspections from 2011 
to 2014 were added to exposure profiles, resulting in a total of 3,364 
samples (2,483 for general industry and 881 for construction) in the 
final exposure profiles. In total, these were obtained from 683 source 
documents (see Table VII-6).
    The exposure profiles characterize what OSHA considers to be the 
baseline, or current, exposures for each job category or application 
group. Where sufficient information on control measures was available, 
the exposure profiles were subdivided into sample results with and 
without controls and the controls were discussed in the baseline 
conditions section. OSHA also discusses the sampling results associated 
with specific controls in the baseline conditions section. In these 
cases, the exposure profiles include exposures associated with a range 
of controlled and uncontrolled exposure scenarios.
[GRAPHIC] [TIFF OMITTED] TR25MR16.041

    The exposure profiles include silica exposure data only for 
employees in the United States. Information on international exposure 
levels is occasionally referenced for perspective or in discussions of 
control options. The rule covers three major polymorphs of crystalline 
silica (i.e., quartz, cristobalite, and tridymite). However, the vast 
majority of crystalline silica encountered by employees in the United 
States is in the quartz form, and the terms crystalline silica and 
quartz are often used interchangeably. Unless specifically indicated 
otherwise, all silica exposure data, samples, and results discussed in 
the technological feasibility analysis refer to personal breathing zone 
(PBZ) measurements of respirable crystalline silica.
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    \22\ OSHA silica Special Emphasis Program (SEP) inspection 
reports are from inspections conducted by OSHA compliance safety and 
health officers (CSHOs) under the silica National Emphasis Program 
between 1993 and 2000.
---------------------------------------------------------------------------

    In general industry and maritime, the exposure profiles in the 
technological feasibility analysis consist mainly of full-shift 
samples, collected over periods of 360 minutes or more (see

[[Page 16435]]

Table IV-02-G in the FEA). By using this criterion, OSHA ensured that 
the samples included in the exposure profiles were collected for at 
least three-quarters of a typical 8-hour shift and therefore captured 
most activities involving exposure to silica at which the employee 
spends a substantial amount of time (Document ID 0845, pp. 38-40; see 
Table IV-02-G in the FEA). Due to the routine nature of most job 
activities in general industry, OSHA assumed that, for the partial 
shift samples of less than 480 minutes, the same level of exposure as 
measured during the sampled portion of the shift continued during the 
smaller, unsampled portion. OSHA considers the 6-hour (360-minute) 
sampling duration to be a reasonable criterion for including a sample 
because it limits the extent of uncertainty about general industry/
maritime employees' true exposures, as no more than 25 percent of an 8-
hour shift would be unsampled. The sample result is therefore assumed 
to be representative of an 8-hour time-weighted average (TWA). 
Moreover, by relying primarily on sampling results 360 minutes or 
greater, OSHA minimized the number of results included in the profiles 
reported as below the limit of detection (LOD). The LOD for an 
analytical method refers to the smallest mass of silica that can be 
detected on the filter used to collect the air sample. Many 
laboratories currently report an LOD of 10 [mu]g or lower for quartz 
samples (Document ID 0666). As discussed in the Methodology section of 
Chapter IV of the FEA, relying primarily on samples with a duration of 
360 minutes or greater allows OSHA to draw the conclusion that any 
sample results reported as non-detect for silica are at most 16 [mu]g/
m\3\, and well below the action level of 25 [mu]g/m\3\.
    In the construction industry, approximately 43 percent of the 
sampling data used in the exposure profiles also consisted of samples 
collected over periods of 360 minutes or more. Most of the samples 
(approximately 70%, or an additional 27%) in the construction industry 
exposure profiles were collected over periods of 240 minutes or more 
(see Table IV-02-G in the FEA). This allows OSHA to draw the conclusion 
that any sample results reported as non-detect are below the action 
level of 25 [mu]g/m\3\ (see Table IV-2-F in the FEA). Construction 
workers typically spend their shifts working at multiple discrete tasks 
and do not normally engage in any one task for the entire duration of a 
shift; these varied tasks can include tasks that generate exposure to 
respirable crystalline silica (Document ID 0677). Consequently, for 
construction, OSHA assumed zero exposure during the unsampled portion 
of the employee's shift unless there was evidence that silica exposures 
continued for the entire shift. For example, if a sample measured an 
average of 100 [mu]g/m\3\ over 240 minutes (4 hours), the result would 
be recorded as 50 [mu]g/m\3\ TWA for a full 8-hour shift (480 minutes).
    The Construction Industry Safety Coalition (CISC), comprised of 25 
trade associations, was critical of several aspects of OSHA's 
feasibility analysis. CISC objected to the assumption of zero exposure 
for the unsampled portion of the work shift when calculating 8-hour 
TWAs for the construction exposure profiles. It claimed that assuming 
zero exposure underestimated TWA exposure levels when compared with the 
alternative assumption used for general industry that the exposure 
level measured during the sampled time period remained at the same 
level during the unsampled period (Document ID 2319, pp. 21-25). While 
there would be some uncertainty whichever assumption OSHA used, OSHA 
concludes that the no-exposure assumption for unsampled portions of a 
shift produces a more accurate result than the assumption of continued 
exposure at the same level because of the widely-recognized differences 
in work patterns between general industry and construction operations. 
In general industry, most operations are at a fixed location and 
involve manufacturing processes that remain relatively constant over a 
work shift. Also, most of the sample durations in general industry were 
360 minutes or longer, and therefore were more likely to be 
representative of 8-hour TWA exposures. In contrast, construction work 
is much more variable with respect to the location of the work site, 
the number of different tasks performed, and the duration of tasks 
performed. As stated above, tasks that generate exposure to respirable 
crystalline silica in construction are often performed on an 
intermittent basis (e.g., Document ID 0677).
    OSHA's conclusion that the variability in sample durations for the 
samples taken by OSHA in the construction industry more accurately 
reflects the variability in exposure duration for these activities thus 
comports with empirical experience. An assumption that exposure levels 
during short-term tasks continued for the entire work shift would 
substantially overestimate the actual 8-hour TWA exposures. The 
Building and Construction Trades Department, AFL-CIO (BCTD) supported 
OSHA's assumptions on work patterns, stating ``OSHA correctly treated 
the unsampled time as having `zero exposure' in its technological 
feasibility assessment'' (Document ID 4223, pp. 16-17). Its conclusion 
was based on research performed by The Center to Protect Workers' 
Rights, which developed a task-based exposure assessment model for the 
construction industry that combines air sampling with task observations 
and task durations in order to assess construction workers' exposure to 
workplace hazards (Susi, et al., 2000, Document ID 4073, Attachment 
8c). This model, when applied to masonry job sites, found that 
employees spent much of their shifts performing non-silica-generating 
tasks, both before and after the task involving silica exposure 
(Document ID 4223, p. 16; 4073, Attachment 3a, pp. 1-2). BCTD indicated 
that it was reasonable to assume these types of work patterns would be 
similar for other construction tasks (Document ID 4223, pp. 16-17).
    CISC also commented that OSHA did not account for the varying 
amounts of crystalline silica that could exist in materials being 
disturbed by employees, and that OSHA did not account for differences 
in exposure results ``due solely to what part of the country the 
activity took place in'' (Document ID 2319, pp. 26-27). OSHA has 
determined that the sampling data relied on to establish baseline 
silica exposures are representative of the range of silica content in 
materials worked on by construction workers. Information on the percent 
silica content of the respirable dust sampled was available for 588 of 
the 881 samples used in the exposure profiles for construction tasks. 
The silica content in these samples ranged from less than 1 percent 
(non-detect) to 50 percent, with an average silica content of 9.1 
percent. Thus, the sample results in the exposure profiles reflect the 
range in the silica content of the respirable dust sampled by OSHA at 
construction work sites. Similarly, the exposure profiles contain 
exposure results from many different construction tasks taken in a 
variety of locations around the country under different weather 
conditions. Therefore, OSHA concludes that the exposure data used in 
the exposure profiles are the best available evidence of actual 
exposures in construction representing nationwide weather patterns, and 
that these data reflect the broad range of silica exposures experienced 
by employees in the construction industry.
    Each section in the technical feasibility analysis presented in 
Chapter

[[Page 16436]]

IV of the FEA begins with descriptions of the manufacturing or 
industrial process or construction activity that has potential exposure 
to respirable crystalline silica, each job category or construction 
task with exposure, and the major activities and sources of exposure. 
Exposure profiles based on the available sampling information are then 
presented and used to characterize the baseline exposures and 
conditions for each operation or task (including exposure controls 
currently in use). Based on the profile of baseline exposures, each 
section next includes a description of additional engineering and work 
practice controls that can be implemented to reduce employee exposures 
to at least the rule's PEL. In addition, comments and other evidence in 
the record relating to the description of the industry sector or 
application group, the exposure profile and baseline conditions, and 
the need for additional controls are discussed in each section. 
Finally, based on the exposure profile and assessment of available 
controls and other pertinent evidence in the record, each section 
includes a feasibility determination for each operation, task, or 
activity, including an overall feasibility determination where more 
than one operation, task, or activity is addressed in the section.
    In particular, OSHA evaluated information and testimony from the 
record on the effectiveness of engineering and work practice controls 
and either: (1) Identified controls that have been demonstrated to 
reduce exposures to 50 [mu]g/m\3\ or below; or (2) evaluated the extent 
to which baseline exposures would be reduced to 50 [mu]g/m\3\ or below 
after applying the percent reduction in respirable silica or dust 
exposure that has been demonstrated for a given control in the 
operation or task under consideration or, in some cases, in analogous 
circumstances. In some cases, the evidence demonstrates that most 
exposures are already below the PEL. OSHA considers the evidence relied 
on in making its feasibility determinations to be the best available 
evidence on these issues.
    For general industry and maritime, the additional engineering 
controls and work practices identified by OSHA consist of equipment and 
approaches that are widely available and are already used in many 
applications. In some cases, the same technology can be transferred or 
adapted to similar operations in other industry sectors covered under 
the scope of this rule. Such controls and work practices include 
implementing and maintaining local exhaust ventilation (LEV) systems 
with dust collection systems (such as integrated material transfer 
stations); enclosing a conveyor of silica-containing material or other 
containment systems; worker isolation; process modifications; dust 
suppression, systems such as water sprays; and housekeeping. In many 
cases, a combination of controls is necessary to control exposures to 
silica. In general industry, enclosed and ventilated equipment is often 
already in use. For example, most paint and coating production 
operations have switched from manual transfer of raw materials 
containing crystalline silica to integrated bag dumping stations 
equipped with well-ventilated enclosures and bag compactors (e.g., 
Document ID 0199, pp. 9-10; 0943, p. 87; 1607 p. 10-19; 1720, p. IV-
237). Where the evidence shows that a type of control like the material 
transfer system is already being used in a sector covered by the rule, 
OSHA is able to conclude that it can be used more widely in that sector 
as an additional control or can be adapted to other industry sectors 
for use during similar operations (see sections IV-15 Paint and 
Coatings, IV-16 Porcelain Enameling, IV-11 Glass, and IV-05 Concrete 
Products, of the FEA for additional information).
    For construction, the exposure controls contained in Table 1 of the 
rule consist primarily of water-based dust suppression systems, and LEV 
systems that are integrated into hand tools and heavier equipment. As 
shown in Chapter IV of the FEA, such systems are commercially available 
from several vendors. In addition, equipment such as filtered, 
ventilated booths or cabs and water-based systems for suppressing 
fugitive dust generated by crushers and heavy equipment are available 
to control exposures of construction workers to respirable crystalline 
silica.
    OSHA received numerous comments that disputed OSHA's preliminary 
conclusion in the Notice of Proposed Rulemaking (NPRM) that a PEL of 50 
[mu]g/m\3\ TWA was technologically feasible. These comments addressed 
two general areas of concern: (1) Whether sampling and analytical 
methods are sufficiently accurate to reliably measure respirable 
crystalline silica concentrations at levels around the PEL and action 
level; and (2) whether engineering and work practice controls can 
reduce exposures from current levels to the lower levels required to 
comply with the new standards. These issues and OSHA's technological 
feasibility findings are discussed in the sections that follow. Much 
more detail can be found in Chapter IV of the FEA.
2. Feasibility Determination for Sampling and Analytical Methods
    As explained in Pertinent Legal Authority (Section II of this 
preamble to the final rule), a finding that a standard is 
technologically feasible requires that ``provisions such as exposure 
measurement requirements must also be technologically feasible'' (see 
Forging Indust. Ass'n v. Sec'y of Labor, 773 F.2d 1436, 1453 (4th Cir. 
1985)). Thus, part of OSHA's technological feasibility assessment of a 
new or revised health standard includes examining whether available 
methods for measuring worker exposures have sufficient sensitivity and 
precision to ensure that employers can evaluate compliance with the 
standard and that workers have accurate information regarding their 
exposure to hazardous substances. Consistent with the Supreme Court's 
definition of ``feasibility'', OSHA finds that it is feasible to 
measure worker exposures to a hazardous substance if achieving a 
reasonable degree of sensitivity and precision with sampling and 
analytical methods is ``capable of being done'' (Am. Textile Mfrs. 
Inst., Inc. v. Donovan, 452 U.S. 490, 509-510 (1981)). OSHA also notes 
that its analysis of the technological feasibility of the sampling and 
analysis of respirable crystalline silica must be performed in 
recognition of the fact that, as recognized by federal courts of 
appeals, measurement error is inherent to sampling (Nat'l Min. Assoc. 
v. Sec'y, U.S. Dep't of Labor, Nos. 14-11942, 14-12163, slip op. at 55 
(11th Cir. Jan. 25, 2016); Am. Mining Cong. v. Marshall, 671 F.2d 1251, 
1256 (10th Cir. 1982)). ``Since there is no perfect sampling method, 
the Secretary has discretion to adopt any sampling method that 
approximates exposure with reasonable accuracy.'' Am. Mining Cong. v. 
Marshall, 671 F.2d at 1256.
    Since the late 1960s, exposures to respirable crystalline silica 
(hereinafter referred to as ``silica'') have typically been measured 
using personal respirable dust samplers coupled with laboratory 
analysis of the crystalline silica content of the collected airborne 
dust. The laboratory analysis is usually performed using X-ray 
diffraction (XRD) or infrared spectroscopy (IR). A colorimetric method 
of analysis that was used by a few laboratories has now been phased out 
(Harper et al., 2014, Document ID 3998, Attachment 8, p. 1). OSHA has 
successfully used XRD analysis since the early 1970s to enforce its 
previous PELs for crystalline silica, which, for general industry, were 
approximately equivalent to 100 micrograms per cubic meter ([mu]g/m\3\) 
for quartz and 50 [mu]g/m\3\ for cristobalite and

[[Page 16437]]

tridymite (and within the range of about 250 [mu]g/m\3\ to 500 [mu]g/
m\3\ for quartz in construction). There are no other generally accepted 
methods for measuring worker exposure to respirable crystalline silica.
    The ability of current sampling and analytical methods to 
accurately measure worker exposures to respirable crystalline silica 
was a subject of much comment in the rulemaking record. In particular, 
the Chamber of Commerce (Chamber) and American Chemistry Council (ACC) 
submitted comments and testimony maintaining that existing methods do 
not measure respirable crystalline silica exposures with sufficient 
accuracy to support OSHA's proposal in the Notice of Proposed 
Rulemaking to reduce the PEL to 50 [mu]g/m\3\ and establish the 25 
[mu]g/m\3\ action level (Document ID 2285; 2288, pp. 17-21; 2307, 
Attachment A, pp. 198-227; 4209, pp. 129-155; 3436, p. 8; 3456, pp. 18-
19; 3460; 3461; 3462; 4194, pp. 17-21). Similar views were expressed by 
several other rulemaking participants (e.g., Document ID 2056, p. 1; 
2085, p. 3; 2174; 2185, pp. 5-6; 2195, Attachment 1, p. 37; 2276, pp. 
4-5; 2317, p. 2; 2379, Comments, pp. 28-30; 4224, pp. 11-14; 4232, 
Attachment 1, pp. 3-24). Specifically, these commenters argue that, due 
to several asserted sources of error, current sampling and analytical 
methods do not meet the NIOSH accuracy criterion of 25 
percent (NIOSH Manual of Analytical Methods, http://www.cdc.gov/niosh/docs/95-117/). Their arguments include: (1) That there is sampling 
error attributed to bias against the particle-size selection criteria 
that defines the performance of the samplers and variation in 
performance between sampling devices; (2) that the accuracy and 
precision of the analytical method at the low levels of silica that 
would be collected at the revised PEL and action level is less than 
that in the range of the previous PELs for silica, particularly in the 
presence of interfering substances; and (3) variation between 
laboratories analyzing comparable samples adds an unacceptable degree 
of uncertainty. After considering all of the testimony and evidence in 
the record, OSHA rejects these arguments and, as discussed below, 
concludes that it is feasible to obtain measurements of respirable 
crystalline silica at the final rule's PEL and action level with 
reasonable accuracy.
    OSHA is basing its conclusions on the following findings, which are 
described in detail in this section. First, although there is variation 
in the performance of respirable dust samplers, studies have 
demonstrated that, for the majority of work settings, samplers will 
perform with an acceptable level of bias (as defined by international 
standards) as measured against internationally recognized particle-size 
selection criteria that define respirable dust samplers. This means 
that the respirable dust mass collected by the sampler will be 
reasonably close to the mass that would be collected by an ideal 
sampler that exactly matches the particle-size selection criteria. In 
addition, OSHA finds that the measure of precision of the analytical 
methods for samples collected at crystalline silica concentrations 
equal to the revised PEL and action level is only somewhat higher 
(i.e., somewhat less precise) than that for samples collected at 
concentrations equal to the previous, higher PELs. Further, the 
analytical methods can account for interferences such that, with few 
exceptions, the sensitivity and precision of the method are not 
significantly compromised. Studies of measurement variability between 
laboratories, as determined by proficiency testing, have demonstrated a 
significant decline in inter-laboratory variability in recent years. 
Improvements in inter-laboratory variability have been attributed to 
changes in proficiency test procedures as well as greater 
standardization of analytical procedures among laboratories. Finally, 
although measurement variability increases at low sample loads compared 
to sample loads in the range of the former PELs, OSHA finds, based on 
these studies, that the magnitude of this increase has also declined in 
recent years.
    Several rulemaking participants commented that OSHA's analysis of 
the feasibility of sampling and analytical methods for crystalline 
silica was well supported and sound (Document ID 2080, pp. 3-4; 2244, 
p. 3; 2371, Attachment 1, p. 5; 3578, Tr. 941; 3586, Tr. 3284; 3577, 
Tr. 851-852; 4214, pp. 12-13; 4223, pp. 30-33). Gregory Siwinski, CIH, 
and Dr. Michael Lax, Medical Director of Upstate Medical University, an 
occupational health clinical center, commented that current laboratory 
methods can measure respirable crystalline silica at the 50 [mu]g/m\3\ 
PEL and 25 [mu]g/m\3\ action level, and that they have measured 
exposures below the action level (Document ID 2244, p. 3). Dr. Celeste 
Montforton of the George Washington School of Public Health testified 
that ``[i]ndustrial hygienists, company safety personnel, consultants, 
and government inspectors have been conducting for decades workplace 
sampling for respirable silica . . .'' and that some governments, such 
as Manitoba and British Columbia, are successfully collecting and 
analyzing samples to determine compliance with their occupational 
exposure limits of 25 [mu]g/m\3\ (Document ID 3577, Tr. 851-852). Dr. 
Frank Mirer of the CUNY School of Public Health, formerly with the UAW 
and on behalf of the AFL-CIO, stated that ``[a]ir sampling is feasible 
at 25 [mu]g/m\3\ and below for [a] full shift and even for part shift. 
It was dealt with adequately in the OSHA proposal'' (Document ID 3578, 
Tr. 941).
    The ACC, Chamber, and others base their argument that sampling and 
analytical methods for respirable crystalline silica are insufficiently 
precise on strict adherence to NIOSH's accuracy criterion of 25 percent at a 95-percent confidence level for chemical sampling 
and analysis methods (http://www.cdc.gov/niosh/docs/95-117/). The ACC 
pointed out that ``OSHA standards typically reflect the NIOSH Accuracy 
Criterion by requiring employers to use a method of monitoring and 
analysis that has an accuracy of plus or minus 25 percent . . . ,'' and 
cited a number of OSHA standards where the Agency has included such 
requirements (benzene, 29 CFR 1910.1028; lead (which requires a method 
accuracy of 20%), 29 CFR 1910.1025; cadmium, 29 CFR 
1910.1027; chromium (VI), 29 CFR 1910.1026) (Document ID 4209, p. 129). 
However, the NIOSH accuracy criterion is not a hard, bright-line rule 
in the sense that a sampling and analytical method must be rejected if 
it fails to meet this level of accuracy, but is rather a goal or target 
to be used in methods development. Where evidence has shown that a 
method does not meet the accuracy criterion at the PEL or action level, 
OSHA has stipulated a less rigorous level of accuracy to be achieved. 
For example, OSHA's acrylonitrile standard requires use of a method 
that is accurate to 35 percent at the PEL and 50 percent at the action level (29 CFR 1910.1045), and several 
OSHA standards require that 35 percent accuracy be obtained 
at the action level (arsenic, 29 CFR 1910.1018; ethylene oxide, 29 CFR 
1910.1047; formaldehyde, 29 CFR 1910.1048; 1,3-butadiene, 29 CFR 
1910.1051; methylene chloride, 29 CFR 1910.1052). As discussed below, 
the precision of the sampling and analytical method for crystalline 
silica, as currently implemented using OSHA Method ID-142 for X-ray 
diffraction, is about 21 percent for quartz and 
cristobalite.
    In the remainder of this section, OSHA first describes available 
respirable dust sampling methods and

[[Page 16438]]

addresses comments and testimony related to the performance and 
accuracy of respirable dust samplers. Following that discussion, OSHA 
summarizes available analytical methods for measuring crystalline 
silica in respirable dust samples and addresses comments and evidence 
regarding analytical method precision, the presence of interfering 
materials, and reported variability between laboratories analyzing 
comparable samples.
a. Respirable Dust Sampling Devices
    Respirable dust comprises particles small enough that, when 
inhaled, they are capable of reaching the pulmonary region of the lung 
where gas exchange takes place. Measurement of respirable dusts 
requires the separation of particles by size to assess exposures to the 
respirable fraction of airborne dusts. A variety of different 
industrial hygiene sampling devices, such as cyclones and elutriators, 
have been developed to separate the respirable fraction of airborne 
dust from the non-respirable fraction. Cyclones are the most commonly 
used size-selective sampling devices, or ``samplers,'' for assessing 
personal exposures to respirable dusts such as crystalline silica. The 
current OSHA (ID-142, revised December 1996, Document ID 0946) and 
NIOSH (Method 7500, Document ID 0901; Method 7602, 0903; Method 7603, 
http://www.cdc.gov/niosh/docs/2003-154/pdfs/7603.pdf) methods for 
sampling and analysis of crystalline silica specify the use of 
cyclones.
    Although respirable dust commonly refers to dust particles having 
an aerodynamic diameter of 10 [mu]m (micrometer) or less, it is more 
precisely defined by the collection efficiency of the respiratory 
system as described by a particle collection efficiency model. These 
models are often depicted by particle collection efficiency curves that 
describe, for each particle size range, the mass fraction of particles 
deposited in various parts of the respiratory system. These curves 
serve as the ``yardsticks'' against which the performance of cyclone 
samplers should be compared (Vincent, 2007, Document ID 1456). Figure 
VII-1 below shows particle collection efficiency curves for two 
particle size selection criteria: The criteria specified in the 1968 
American Conference of Governmental Industrial Hygienists (ACGIH) 
Threshold Limit Value (TLV) for respirable dust, which was the basis 
for the prior OSHA general industry silica PEL, and an international 
specification by the International Organization for Standardization 
(ISO) and the Comit[eacute] Europ[eacute]en de Normalisation (CEN) 
known as the ISO/CEN convention, which was adopted by ACGIH in 1994 and 
is the basis for the definition of respirable crystalline silica in the 
final rule. In addition to the curves, which cover the full range of 
particle sizes that comprise respirable dust, particle size collection 
criteria are also often described by their 50-percent respirable ``cut 
size'' or ``cut point.'' This is the aerodynamic diameter at which 50 
percent of the particle mass is collected, i.e., the particle size that 
the sampler can collect with 50-percent efficiency. Particles with a 
diameter smaller than the 50-percent cut point are collected with an 
efficiency greater than 50 percent, while larger-diameter particles are 
collected with an efficiency less than 50 percent. The cut point for 
the 1968 ACGIH specification is 3.5 [mu]m and for the ISO/CEN 
convention is 4.0 [mu]m (Lippman, 2001, Document ID 1446, pp. 107, 
113).
[GRAPHIC] [TIFF OMITTED] TR25MR16.042


[[Page 16439]]


    For most workplace conditions, the change in the criteria for 
respirable dust in the final rule would theoretically increase the mass 
of respirable dust collected over that measured under the previous 
criteria by an amount that depends on the size distribution of airborne 
particles in the workplace. Soderholm (1991, Document ID 1661) examined 
these differences based on 31 aerosol size distributions measured in 
various industrial workplaces (e.g., coal mine, lead smelter, brass 
foundry, bakery, shielded metal arc [SMA] welding, spray painting, 
pistol range) and determined the percentage increase in the mass of 
respirable dust that would be collected under the ISO/CEN convention 
over that which would be collected under the 1968 ACGIH criteria. 
Soderholm concluded that, for all but three of the 31 size 
distributions that were evaluated, the increased respirable dust mass 
that would be collected using the ISO/CEN convention for respirable 
dust instead of the 1968 ACGIH criteria would be less than 30 percent, 
with most size distributions (25 out of the 31 examined, or 80 percent) 
resulting in a difference of between 0 and 20 percent (Document ID 
1661, pp. 248-249, Figure 1). In the PEA, OSHA stated its belief that 
the magnitude of this effect does not outweigh the advantages of 
adopting the ISO/CEN convention. In particular, most respirable dust 
samplers on the market today are designed and calibrated to perform in 
a manner that closely conforms to the international ISO/CEN convention.
    Incorporating the ISO/CEN convention in the definition of 
respirable crystalline silica will permit employers to use any sampling 
device that conforms to the ISO/CEN convention. There are a variety of 
these cyclone samplers on the market, such as the Dorr-Oliver, Higgins-
Dewell (HD), GK2.69, SIMPEDS, and SKC aluminum. In the PEA, OSHA 
reviewed several studies demonstrating that these samplers collect 
respirable particles with efficiencies that closely match the ISO/CEN 
convention (Document ID 1720, pp. IV-21--IV-24). In addition to cyclone 
samplers, there are also personal impactors available for use at flow 
rates from 2 to 8 L/min that have been shown to conform closely with 
the ISO/CEN convention (Document ID 1834, Attachment 1). Cyclones and 
impactors both separate particles by size based on inertia. When an 
airstream containing particles changes direction, smaller particles 
remain suspended in the airstream and larger ones impact a surface and 
are removed from the airstream. Cyclones employ a vortex to separate 
particles centrifugally, while impactors use a laminar airflow around a 
flat surface such that particles in the desired size range impact onto 
the surface.
    The current OSHA sampling method for crystalline silica, ID-142, is 
the method used by OSHA to enforce the silica PELs and is used by some 
employers as well. It specifies that a respirable sample be collected 
by drawing air at 1.7  0.2 liters/minute (L/min) through a 
Dorr-Oliver 10 millimeter (mm) nylon cyclone attached to a cassette 
containing a 5-[mu]m pore-size, 37-mm diameter polyvinyl chloride (PVC) 
filter (Document ID 0946). NIOSH sampling and analysis methods for 
crystalline silica (Method 7500, Method 7602, Method 7603) have also 
adopted the ISO/CEN convention with flow rate specifications of 1.7 L/
min for the Dorr-Oliver 10-mm nylon cyclone and 2.2 L/min for the HD 
cyclone (Document ID 0901; 0903). Method 7500 also allows for the use 
of an aluminum cyclone at 2.5 L/min. NIOSH is revising its respirable 
dust method to include any sampler designed to meet the ISO/CEN 
criteria (Document ID 3579, Tr. 218).
    The devices discussed above, when used at the appropriate flow 
rates, are capable of collecting a quantity of respirable crystalline 
silica that exceeds the quantitative detection limit for quartz (the 
principle form of crystalline silica) of 10 [mu]g for OSHA's XRD method 
(Document ID 0946). For several scenarios based on using various 
devices and sampling times (8-hour, 4-hour, and 1-hour samples), OSHA 
calculated the amount of respirable quartz that would be collected at 
quartz concentrations equal to the existing general industry PEL, the 
proposed (and now final) rule's PEL, and the proposed (and now final) 
rule's action level. As seen in Table IV.3-A, computations show that 
the 10-mm nylon Dorr-Oliver operated at an optimized flow rate of 1.7 
L/min, the aluminum cyclone operated at 2.5 L/min, the HD cyclone 
operated at 2.2 L/min, and the GK2.69 operated at 4.2 L/min will all 
collect enough quartz during an 8-hour or 4-hour sampling period to 
meet or exceed the 10 [micro]g quartz limit of quantification for OSHA 
Method ID-142. Therefore, each of the commercially available cyclones 
is capable of collecting a sufficient quantity of quartz to exceed the 
limit of quantification when airborne concentrations are at or below 
the action level, provided that at least 4-hour air samples are taken. 
Table VII-7 also shows that the samplers can collect enough silica to 
meet the limit of quantification when the airborne respirable silica 
concentration is below the action level of 25 [mu]g/m\3\, in one case 
as low as 5 [mu]g/m\3\.

[[Page 16440]]

[GRAPHIC] [TIFF OMITTED] TR25MR16.043

    A comment from the National Rural Electric Cooperative Association 
(NRECA) stated that the current OSHA and NIOSH analytical methods 
require sampling to collect a minimum of 400 liters of air, and that at 
the flow rates specified for current samplers, sampling would have to 
be performed for approximately 2.5 to 4 hours; however, this is 
considerably longer than most construction tasks performed in 
electrical transmission and distribution work, which tend to last 2 
hours or less (Document ID 2365, pp. 2, 6-7). OSHA does not view this 
discrepancy to be a problem. The minimum sampling times indicated in 
the OSHA and NIOSH methods contemplate that exposure occurs over most 
of the work shift. Construction operations frequently involve shorter-
term tasks after which there is no further exposure to respirable 
crystalline silica. In those situations, OSHA often does not itself 
continue sampling during inspections and does not expect employers to 
continue sampling when there is no exposure to silica, and considers 
the sampling result that is obtained from shorter-term task sampling to 
be sufficient to represent a worker's 8-hour time-weighted-average 
(TWA) exposure, which can be calculated assuming no exposure for the 
period of the shift that is not sampled. If the airborne concentration 
of silica for the task is low, the sampling result would likely be 
below the limit of quantification. In that case, it would be safe for 
the employer to assume that the exposure is below the action level.
Transition to ISO-CEN Criteria for Samplers
    In the final rule, OSHA is adopting the ISO/CEN particle size-
selective criteria for respirable dust samplers used to measure 
exposures to respirable crystalline silica. Under the ISO/CEN 
convention, samplers should collect 50 percent of the mass of particles 
that are 4 [mu]m in diameter (referred to as the cut point), with 
smaller particles being collected at higher efficiency and larger 
particles being collected at lower efficiency. Particles greater than 
10 [mu]m in diameter, which are not considered to be respirable, are to 
be excluded from the sample based on the ISO/CEN convention (Document 
ID 1446, pp. 112-113).
    Several rulemaking participants supported OSHA's proposed adoption 
of the ISO/CEN criteria for respirable dust samplers (Document ID 1730; 
1969; 3576, Tr. 290; 3579, Tr. 218-219; 4233, p. 4). For example, a 
representative of SKC, Inc., which manufactures samplers used to 
collect respirable crystalline silica, stated that:

    Adoption of the ISO/CEN performance standard for respirable dust 
samplers by OSHA will bring the U.S. regulatory standards in line 
with standards/guidelines established by other occupational health 
and safety agencies, regulatory bodies, and scientific consensus 
organizations around the world. It will also align OSHA performance 
criteria for respirable dust samplers to that of NIOSH (Document ID 
1730, pp. 1-2).

    As discussed above, OSHA's previous (and currently enforceable) 
general industry PEL for crystalline silica was based on a 1968 ACGIH 
definition, which specified a model with a cut point of 3.5 [mu]m. 
Based on available studies conducted over 40 years ago, the Dorr-Oliver 
10-mm cyclone was thought to perform closely to this specification. As 
such, it is the sampling device specified in OSHA's respirable dust 
sampling and analytical methods, including Method ID-142 for respirable 
crystalline silica (Document ID 0946). For most sizes of respirable 
particles, the ISO/CEN convention specifies a greater efficiency in 
particle collection than does the 1968 ACGIH model; consequently, 
samplers designed to meet the ISO/CEN convention will capture somewhat 
greater mass of airborne particle than would a sampler designed to the 
1968 ACGIH model, with the magnitude of the increased mass dependent on 
the distribution of particle sizes in the air. For most particle size 
distributions encountered in workplaces, the increase in dust mass 
theoretically collected under the ISO/CEN convention compared to the 
ACGIH model would be 25 percent or less (Soderholm, 1991, Document ID 
1661).
    Several rulemaking participants commented that moving from the 1968 
ACGIH model to the ISO/CEN convention effectively decreased the PEL and 
action level below the levels intended, since more dust would be 
collected by samplers that conform to

[[Page 16441]]

the ISO/CEN convention than by those that conform to the 1968 ACGIH 
model (Document ID 2174; 2195, p. 30; 2285, pp. 3-4; 2307, Attachments 
10, p. 19, and 12, p. 3; 2317, p. 2; 3456, p. 10; 4194, pp. 15-16). For 
example, the Chamber commented that adopting the ISO/CEN specification 
``can result in citations for over exposure to quartz dust where none 
would have been issued prior to the adoption of this convention'' 
(Document ID 2288, p. 16). OSHA disagrees with this assessment because, 
based on more recent evaluations (Bartley et al., 1994, Document ID 
1438, Attachment 2; Lee et al., 2010, 3616; 2012, 3615), the Dorr-
Oliver 10-mm cyclone that has been used by the Agency for enforcement 
of respirable dust standards for decades has been found to perform 
reasonably closely (i.e., with an acceptable level of bias) to the ISO/
CEN specification when operated at the 1.7 L/min flow rate specified by 
OSHA's existing method. Consequently, OSHA and employers can continue 
to use the Dorr-Oliver cyclone to evaluate compliance against the final 
PEL of 50 [mu]g/m\3\ without having to change equipment or procedures, 
and thus would not be collecting a greater quantity of dust than 
before. Furthermore, OSHA notes that other ISO/CEN-compliant samplers, 
such as the SKC 10-mm aluminum cyclone and the HD cyclone specified in 
the NIOSH Method 7500, are already widely used by investigators and 
employers to evaluate exposures to respirable crystalline silica 
against benchmark standards. Therefore, the change from the ACGIH 
convention to the ISO/CEN convention is more a continuation of the 
status quo than a drastic change from prior practice.
    Other rulemaking participants argued that moving to the ISO/CEN 
convention effectively invalidates OSHA's risk and feasibility analyses 
since the exposure data that underlie these analyses were obtained 
using devices conforming to the 1968 ACGIH specification. For example, 
Thomas Hall, testifying for the Chamber, stated that moving to the ISO/
CEN convention ``would produce a difference in [current] exposure 
results from . . . historical measurements that have been used in the 
risk assessments'' (Document ID 3576, Tr. 435). Similarly, in its pre-
hearing comments, the ACC argued that:

    When OSHA conducted technological feasibility studies for 
attaining the proposed 50 [mu]g/m\3\ PEL, the Agency based its 
decisions on samples collected using the current ACGIH method, not 
the proposed ISO/CEN method. Thus, the switch to the ISO/CEN 
definition will have two impacts on feasibility. First, it will add 
uncertainty regarding OSHA's technological feasibility determination 
because greater reductions in exposure will be required to achieve a 
50 [mu]g/m\3\ PEL measured by the ISO/CEN definition than by the 
ACGIH definition that OSHA applied. Second, OSHA's use of the ACGIH 
definition to estimate compliance costs causes the Agency to 
underestimate the costs of achieving the 50 [mu]g/m\3\ PEL because 
OSHA did not account for the additional workers whose exposures 
would exceed the proposed PEL under the ISO/CEN definition but who 
would be exposed below the proposed PEL if measured under the ACGIH 
definition (Document ID 2307, Attachment 8, p. 9).

    OSHA rejects these arguments for the following reasons. First, with 
respect to the risk information relied on by the Agency, exposure data 
used in the various studies were collected from employer records 
reflecting use of several different methods. Some studies estimated 
worker exposures to silica from particle counts, for which the sampling 
method using impingers does not strictly conform to either the ACGIH or 
ISO/CEN conventions (e.g., Rice et al., Document ID 1118; Park et al., 
Document ID 0405; Attfield and Costello, Document ID 0285; Hughes et 
al., Document ID 1060). Other studies used measurements taken using 
cyclone samplers and modern gravimetric methods of silica analysis 
(e.g., Rice et al. and Park et al., data obtained from cyclone pre-
separator up through 1988, Document ID 1118, 0405; Hughes et al., data 
from 10-mm nylon cyclone through 1998, Document ID 1060). OSHA believes 
it likely that exposure data collected using cyclones in these studies 
likely conformed to the ISO/CEN specification since flow rates 
recommended in the OSHA and NIOSH methods were most likely used. The 
studies by Miller and MacCalman (Document ID 1097) and by Buchanan et 
al. (Document ID 0306) used exposure measurements made with the MRE 
113A dust sampler, which does conform reasonably well with the ISO/CEN 
specification (Gorner et al., Document ID 1457, p. 47). The studies by 
Chen et al. (2001, Document ID 0332; 2005, Document ID 0985) estimated 
worker exposures to silica from total dust measurements that were 
converted to respirable silica measurements from side-by-side 
comparisons of the total dust sampling method with samples taken using 
a Dorr-Oliver cyclone operated at 1.7 L/min, which is consistent with 
the ISO/CEN convention (see Section V, Health Effects, of this preamble 
and OSHA's Preliminary Review of Health Effects Literature and 
Preliminary Quantitative Risk Assessment, Document ID 1711). Thus, it 
is simply not the case that the exposure assessments conducted for 
these studies necessarily reflect results from dust samples collected 
with a device conforming to the 1968 ACGIH particle size-selective 
criteria, and OSHA finds that no adjustment of OSHA's risk estimates to 
reflect exposure measurements consistent with the ISO/CEN convention is 
warranted.
    Second, with respect to the feasibility analysis, OSHA relied on 
exposure data and constructed exposure profiles based principally on 
measurements made by compliance officers using the Dorr-Oliver cyclone 
operated at 1.7 L/min, as the Agency has done since Method ID-142 was 
developed in 1981, well before the 1990 cut-off date for data used to 
construct the exposure profiles. As explained earlier in the section, 
recent research shows that the Dorr-Oliver cyclone operated at this 
flow rate performs in a manner consistent with the ISO/CEN 
specification. Other data relied on by OSHA comes from investigations 
and studies conducted by NIOSH and others who used various cyclones 
that conform to the ISO/CEN specification. Thus, OSHA finds that the 
exposure profiles being relied on to evaluate feasibility and costs of 
compliance do not reflect sample results obtained using the 1968 ACGIH 
model. Instead, the vast majority of sample results relied upon were 
collected in a manner consistent with the requirements of the final 
rule. NIOSH supported this assessment, stating that, given the Dorr-
Oliver sampler operated at a flow rate of 1.7 L/min conforms closely to 
the ISO/CEN convention, ``there is continuation with historic exposure 
data'' (Document ID 4233, p. 4). For these reasons, OSHA finds that it 
is appropriate to rely on the feasibility and cost analyses and 
underlying exposure data without adjustment to account for the final 
rule's adoption of the ISO/CEN specification for respirable dust 
samplers.
Sampling Error
    Several commenters raised issues concerning the accuracy of 
respirable dust samplers in relation to the ISO/CEN criteria, asserting 
that sampling respirable dust is uncertain and inaccurate, and that 
there are numerous sources of error. Chief among these were Dr. Thomas 
Hall of Industrial Hygiene Specialty Resources, LLC, testifying for the 
Chamber, and Paul K. Scott of ChemRisk, testifying for the ACC.
    The Chamber's witnesses and others referenced studies showing that 
all samplers were biased against the ISO/CEN particle-size selection 
convention. This means that the sampler would collect more or less mass 
of respirable particulate than would an ideal sampler

[[Page 16442]]

that exactly conforms to the ISO/CEN convention. OSHA discussed this 
issue in the PEA, noting that most samplers tend to over-sample smaller 
particles and under-sample larger particles, compared to the ISO/CEN 
convention, at their optimized flow rates. This means that, for 
particle size distributions dominated by smaller particles, the sampler 
will collect more mass than would be predicted from an ideal sampler 
that exactly conforms to the ISO/CEN convention. For particle size 
distributions dominated by larger particles in the respirable range, 
less mass would be collected than predicted. In the PEA, OSHA evaluated 
several studies that showed that several cyclone samplers exhibited a 
bias of 10 percent or less for most particle size distributions 
encountered in the workplace. Some of these studies found biases as 
high as 20 percent but only for particle size distributions 
having a large mass median aerodynamic diameter (MMAD) (i.e., 20 
[micro]m or larger) and narrow distribution of particle sizes (i.e., a 
geometric standard deviation (GSD) of 2 or less) (Document ID 1720, pp. 
IV-21--IV-24). Such particle size distributions are infrequently seen 
in the workplace; for well-controlled environments, Frank Hearl of 
NIOSH testified that the GSD for typical particle size distributions 
would be about 2 (Document ID 3579, Tr. 187). Dr. Hall (Document ID 
3576, Tr. 502) testified, similarly, that it would be around 1.8 to 3 
for well-controlled environments and higher for uncontrolled 
environments (see also Liden and Kenny, 1993, Document ID 1450, p. 390, 
Figure 5; Soderholm, 1991,1661, p. 249, Figure 1). Furthermore, a 
particle size distribution with a large MMAD and small GSD would 
contain only a very small percentage (< 10%) of respirable dust that 
would be collected by a sampler optimized to the ISO/CEN criteria 
(Soderholm, 1991, Document ID 1661, p. 249, Figure 2). According to 
Liden and Kenny (1993), ``samplers will perform reasonably well 
providing the absolute bias in sampling is kept to within 10 percent . 
. . this aim can be achieved . . . over the majority of size 
distributions likely to be found in field sampling'' (Document ID 1450, 
p. 390).
    Dr. Hall commented that ``sampling results differ depending on the 
choice of sampler used'' and that published evaluations have shown that 
they ``have different collection efficiencies, specifically with 
respect to particle collection in aerosol clouds with large [MMADs 
greater than] 10 [mu]m'' (Document ID 2285, p. 16). He cited the work 
of Gorner et al. (2001, Document ID 1457), who noted that the cut 
points achieved by different samplers varied considerably and that flow 
rates were optimized to bring their respective cut points closer to the 
ISO/CEN convention, as evidence that commercial samplers do not provide 
consistently similar results. However, OSHA interprets the findings of 
Gorner et al. as actually providing evidence of samplers' consistency 
with the ISO/CEN convention for most particle size distributions 
encountered in the workplace. This study, which was reviewed in OSHA's 
PEA, evaluated 15 respirable dust samplers, most of them cyclones, 
against 175 different aerosol size distributions and evaluated the bias 
and accuracy of sampler performance against the ISO/CEN convention.\23\ 
Gorner et al. found that most of the samplers they tested met the 
international criteria for acceptable bias and accuracy (described by 
Bartley et al., 1994, Document ID 1438, Attachment 2 and Gorner et al., 
2001, 1457); under those criteria, bias is not to exceed 10 percent and 
inaccuracy is not to exceed 30 percent for most of the size 
distributions tested (Document ID 1457, pp. 49, 52; Document ID 1438, 
Attachment 2, p. 254). Gorner et al. concluded that the samplers ``are 
therefore suitable for sampling aerosols within a wide range of 
particle size distributions'' (Document ID 1457, p. 52). Gorner et al. 
also stated that sampler performance should be evaluated by examining 
bias and accuracy rather than simply comparing cut points and slopes 
against the ISO/CEN convention (Document ID 1457, p. 50), as Dr. Hall 
did in his comments.
---------------------------------------------------------------------------

    \23\ Bias means the difference in particle mass collected by a 
sampler as compared to the mass that would be collected by a 
hypothetical ideal sampler that exactly matched the ISO/CEN 
convention. Accuracy includes bias and other sources of error 
related to the testing procedure (e.g., errors in flow rate and 
particle mass analysis)(Document ID 1457, p. 49).
---------------------------------------------------------------------------

    The ACC's witness, Mr. Scott, noted several potential sources of 
sampling error in addition to the conventional 5-percent pump flow rate 
error that is included in OSHA's estimate of sampling and analytical 
error (SAE, discussed further in Section IV-3.2.4--Precision of 
Measurement). These included variation in performance of the same 
cyclone tested multiple times (estimated at 6 percent) and variation 
between different cyclones tested in the same environment (estimated at 
5 percent) (Document ID 2308, Attachment 6, pp. 7-8). Based on 
published estimates of the magnitude of these kinds of errors, Mr. 
Scott estimated a total sampling error of 9.3 percent after factoring 
in pump flow rate error, inter-sampler error, and intra-sampler error; 
this would increase the SAE by 4 percent, for example, from 15 to 19 
percent at 50 [mu]g/m\3\ (Document ID 2308, pp. 8-9). This means that, 
if all sampler error were factored into the SAE, an employer would be 
considered out of compliance with the PEL for an exposure exceeding 
59.5 [micro]g/m\3\, rather than at 57.5 [micro]g/m\3\ if only pump 
error were considered, a difference of only 2 [micro]g/m\3\ in silica 
concentration. OSHA therefore concludes that intra- and inter-sampler 
error of the types described by Mr. Scott do not materially change how 
OSHA would enforce, or how employers should evaluate, compliance with 
the final rule PEL.
    As described above, many different respirable dust samplers have 
been evaluated against the ISO/CEN convention for different particle 
size distributions and, in general, these biases are small for the vast 
majority of particle size distributions encountered in the workplace. 
OSHA concludes that Mr. Scott's estimate likely overstates the true 
total sampling error somewhat because the measurements of sampler bias 
against the ISO/CEN criteria involve accurately measuring and 
maintaining consistent pump flow rates during the testing of the 
samplers; therefore, adding pump flow rate error to estimates of inter- 
and intra-sampler measurement error is redundant. Furthermore, if an 
employer relies on a single type of cyclone sampler, as is OSHA's 
practice, there would be no inter-sampler variability between different 
field samples. If an employer is concerned about this magnitude of 
uncertainty, he or she can choose simply to use the same sampling 
device as OSHA (i.e., the Dorr-Oliver cyclone operated at a flow rate 
of 1.7 L/min, as specified in Method ID-142) and avoid any potential 
measurement uncertainties associated with use of different sampling 
devices.
    The American Foundry Society (AFS) commented that the ASTM Standard 
D4532 for respirable dust sampling includes errors for sampling, 
weighing, and bias, none of which is included in OSHA's pump flow rate 
error (Document ID 2379, p. 29). This ASTM standard describes 
procedures for sampling respirable dust using a 10-mm cyclone, HD 
cyclone, or aluminum cyclone in a manner identical to that prescribed 
in the OSHA and NIOSH methods for sampling and analysis of silica. 
Thus, the kinds of errors identified by AFS are the same as those 
reflected in Mr. Scott's testimony described above, which, as OSHA has

[[Page 16443]]

shown, do not result in substantial uncertainties in exposure 
measurement.
    OSHA further observes that the kinds of sampling errors described 
by rulemaking participants are independent of where the PEL is 
established and are not unique to silica; these biases have existed 
since OSHA began using the Dorr-Oliver cyclone to enforce the previous 
PELs for crystalline silica, as well as many other respirable dust 
standards, over 40 years ago. OSHA also believes that sampling error 
within the range quantified by Mr. Scott would be unlikely to change 
how an employer makes risk management decisions based on monitoring 
results. One Chamber witness, Gerhard Knutson, President of Knutson 
Ventilation, testified that the type of cyclone used to obtain exposure 
measurements for crystalline silica was not typically a consideration 
in designing industrial ventilation systems (Document ID 3576, Tr. 521-
522). Dr. Hall, another Chamber witness, also testified that he has 
used all three sampling devices listed in the NIOSH Method 7500 and has 
not historically made a distinction between them, though he might make 
different decisions today based on the aerosol size distribution 
encountered in a particular workplace (Document ID 3576, Tr. 522-523). 
In his pre-hearing submission, Dr. Hall cited the Gorner et al. (2001, 
Document ID 1457) study as recommending that ``rough knowledge of the 
aerosol size distribution can guide the choice of an appropriate 
sampling technique'' (Document ID 2285, p. 8). OSHA concludes it 
unlikely that, in most instances, it is necessary to obtain such data 
to minimize sampling bias for risk management purposes, given the 
overall magnitude of the bias as estimated by Mr. Scott (i.e., an error 
of less than 10 percent).
High Flow Samplers
    OSHA's PEA also described high-flow samplers, in particular the 
GK2.69 from BGI, Inc., which is run at a flow rate of 4.2 L/min in 
contrast to 1.7 L/min for the Dorr-Oliver and 2.5 L/min for the 
aluminum cyclone. High-flow devices such as this permit a greater 
amount of dust to be collected in low-dust environments, thus improving 
sensitivity and making it more likely that the amount of silica 
collected will fall within the range validated by current analytical 
methods. For example, a Dorr-Oliver run at 1.7 L/min where the silica 
concentration is 50 [mu]g/m\3\ would collect 41 [mu]g of silica over 8 
hours, compared to the GK2.69 run at 4.2 L/min, which would collect 101 
[mu]g of silica (see Table IV.3-A), well within the validation range of 
the OSHA method (i.e., the range over which precision is determined, 50 
to 160 [mu]g) (Document ID 0946, p. 1). Several rulemaking participants 
supported OSHA's proposal to permit use of high-flow samplers that 
conform to the ISO/CEN convention (Document ID 2256, Attachment 3, p. 
12; 3578, Tr. 941; 3586, Tr. 3286-3287; 4233, p. 4). For example, 
William Walsh, representing the American Industrial Hygiene Association 
(AIHA) Laboratory Accreditation Programs, stated that he could measure 
concentrations of silica at the 25 [mu]g action level with sufficient 
precision by using a high-flow device (Document ID 3586, Tr. 3287).
    The performance of high-flow samplers has been extensively studied, 
particularly by Lee et al. (2010, Document ID 3616; 2012, 3615), Stacey 
et al. (2013, Document ID 3618), and Kenny and Gussman (1997, Document 
ID 1444). The Kenny and Gussman study, which was reviewed in OSHA's 
PEA, found the GK2.69 had good agreement with the ISO/CEN convention at 
the 4.2 L/min flow rate, with a cut point of 4.2 [mu]m and a collection 
efficiency curve that was steeper than the ISO/CEN (i.e., it was more 
efficient for smaller particles and less so for larger particles). For 
particle size distributions up to an MMAD of 25 [mu]m and GSD of 1.5 to 
3.5, bias against the ISO/CEN convention was generally between +5 and -
10 percent. Bias was greater (-20 percent) for particle size 
distributions having an MMAD above 10 [mu]m and a low GSD which, 
according to the authors, are not likely to be encountered (Document ID 
1444, p. 687, Figure 7).
    The Lee et al. (2010, Document ID 3616; 2012, 3615) and Stacey 
(2013, Document ID 3618) studies of high-flow sampler performance are 
the product of a collaborative effort between NIOSH and the United 
Kingdom's Health and Safety Executive (HSE) that examined the 
performance of three high-flow samplers; these were the GK2.69, the 
CIP10-R (Arelco ARC, France), and the FSP10 (GSA, Germany). The FSP10 
runs at a flow rate of 10 L/min and the combination of large cyclone 
and heavy-duty pump may be burdensome for workers to wear. The CIP-10 
also runs at 10 L/min and is much smaller and lighter, but uses a 
collection technology different from cyclones, which may be unfamiliar 
to users. According to NIOSH, cyclones operating around 4 L/min ``offer 
a current compromise'' for obtaining higher flow rates without the need 
to use larger personal samplers that may be difficult for workers to 
wear (Document ID 2177, Attachment B, p. 13; 3579, Tr. 163).'' For this 
reason, OSHA's review of these studies focuses on the performance of 
the GK2.69 cyclone.
    Lee et al. (2010, Document ID 3616) tested the GK2.69 against 11 
sizes of monodisperse aerosol and found that, at the 4.2 L/min flow 
rate, the estimated bias against the ISO/CEN convention was positive 
for all particle size distributions (i.e., the sampler collected 
greater mass of particulate than would be predicted from an ideal 
sampler that exactly conformed to ISO/CEN), with a 10-percent 
efficiency for collecting 10 [mu]m particles, compared to 1 percent for 
the ISO/CEN convention. The authors estimated a bias of +40 percent for 
a particle size distribution having a MMAD of 27.5 [mu]m. However, 
adjustment of the flow rate to 4.4 L/min resulted in biases of less 
than 20 percent for most particle size distributions and the collection 
efficiency for 10 [mu]m particles was much closer to the ISO/CEN 
convention (2.5 percent compared to 1 percent). The authors concluded 
that, at the higher flow rate, the GK2.69 cyclone met the international 
standard for sampler conformity to relevant particle collection 
conventions (European Committee for Standardization, EN 13205, cited in 
Lee et al., 2010, Document ID 3616), and would provide relatively 
unbiased measurements of respirable crystalline silica (Document ID 
3616, pp. 706, 708, Figure 5(a)).
    Lee et al. (2012, Document ID 3615) performed a similar evaluation 
of the same samplers using coal dust but included analysis of 
crystalline silica by both XRD and IR. The GK2.69 runs at a flow rate 
of 4.4 L/min collected somewhat more respirable dust and crystalline 
silica than would be predicted from differences in flow rates, compared 
to the 10-mm nylon cyclone, but nearly the same as the Higgins-Dewell 
cyclone. The authors found that the GK2.69 ``showed non-significant 
difference in performance compared to the low-flow rate samplers'' 
(Document ID 3615, p. 422), and that ``the increased mass of quartz 
collected with high-flow rate samplers would provide precise analytical 
results (i.e., significantly above the limit of detection and/or the 
limit of quantification) compared to the mass collected with low-flow 
rate samplers, especially in environments with low concentrations of 
quartz . . .'' (Document ID 3615, p. 413). Lee et al. concluded that 
``[a]ll samplers met the [EN 13205] requirements for accuracy for 
sampling the ISO respirable convention'' (Document ID 3615, p. 424).
    Stacey et al. (2013, Document ID 3618) used Arizona road dust 
aerosols

[[Page 16444]]

to evaluate the performance of high-flow samplers against the Safety In 
Mines Personal Dust Sampler (SIMPEDS), which is the low-flow sampler 
used to measure respirable crystalline silica in the U.K. For the 
GK2.69, use of a flow rate of 4.2 L/min or 4.4 L/min made little 
difference in the respirable mass collected, and there was closer 
agreement between the GK2.69 and SIMPEDS sampler when comparing 
respirable crystalline silica concentration than respirable dust 
concentration, and the difference was not statistically significant 
(Document ID 3618, p. 10). According to NIOSH, the findings by Stacey 
et al. (2013) corroborate those of Lee et al. (2010 and 2012) that the 
GK2.69 meets the ISO/CEN requirements for cyclone performance and that 
either the 4.2 L/min or 4.4 L/min flow rate ``can be used to meet the 
ISO convention within acceptable limits'' (Document ID 2177, p. 13).
    Mr. Scott testified that the high-flow samplers (including the 
GK2.69) studied by Lee et al., (2010 and 2012), ``tended to have a 
substantial bias towards collecting more respirable particulates than 
the low-flow samplers, collecting between 12 percent and 31 percent 
more mass'' because high-flow samplers tend to collect a higher 
proportion of larger particles (Document ID 3582, Tr. 1984). In his 
written testimony, he noted that Lee et al. (2010) reported a nearly 
10-fold higher collection efficiency for 10 [mu]m particles compared to 
the ISO/CEN standard. However, Mr. Scott's testimony ignores Lee et 
al.'s findings that the oversampling of larger particles seen at a flow 
rate of 4.2 L/min was not apparent at the higher 4.4 L/min flow rate 
and that Lee et al. (2010) concluded that agreement with the ISO/CEN 
convention was achieved at the higher flow rate (Document ID 3616, pp. 
706, 708). In addition, oversampling of larger particles at the 4.2 L/
min flow rate was not reported by Lee et al. (2012, Document 3615) or 
Stacey et al. (2013, Document ID 3618).
    Dr. Hall expressed a similar concern as Mr. Scott. He cited Lee et 
al. (2010) as stating that the GK2.69 would collect significantly more 
aerosol mass for particle size distributions having an MMAD of more 
than 6 [mu]m. He also cited Lee et al. (2010 and 2012) for the finding 
that the GK2.69 collects from 1.8 to 3.84 times as much aerosol mass as 
the Dorr-Oliver or Higgins-Dewell cyclones (Document ID 2285, p. 12). 
In his pre-hearing comment, Dr. Hall stated that ``[f]or aerosol clouds 
with a [MMAD] greater than 10 [mu]m, the expected absolute bias can 
range be (sic) between 20 and 60%'' and ``the total variability for the 
method SAE can be as large as 85-90%'' (Document ID 2285, pp. 15-16).
    OSHA notes that both Dr. Hall and Mr. Scott focus their comments 
regarding the performance of high-flow samplers on environments where 
the particle size distribution is characterized by larger particles and 
small variance (GSD). The findings by Lee et al. (2010) show that, at a 
flow rate of 4.2 L/min, under this experimental system, there were 
large positive biases (>20 percent) against the ISO/CEN convention for 
nearly all particle size distributions having MMAD of 5 to 10 [mu]m 
(Document ID 3616, pp. 704-706, Figure 3(b)). However, when the flow 
rate was adjusted to 4.4 L/min, bias exceeding 20 percent was found to 
occur primarily with particle size distributions having GSDs under 2.0 
and MMAD greater than 10 [mu]m (Document ID 3616, p. 707, Figure 5(a)). 
As discussed above, it is rare to encounter particle size distributions 
having relatively large MMADs and small GSDs, so the high variability 
attributed to high-flow samplers by Dr. Hall and Mr. Scott should not 
be of concern for most workplace settings. Further, sampler performance 
is considered acceptable if the bias and accuracy over at least 80 
percent of the remaining portion of the bias map are within acceptable 
limits, which are no more than 10 and 30 percent, respectively 
(Document ID 1457, pp. 49, 52). The Lee et al. studies (2010 and 2012) 
concluded that the high-flow samplers tested met these international 
requirements for accuracy for sampling the ISO/CEN convention, and the 
Stacey et al. (2013) study found that their results compared favorably 
with those of Lee et al. (2012). Therefore, OSHA finds that the 
uncertainties characterized by Dr. Hall and Mr. Scott are exaggerated 
for most workplace situations, and that there is substantial evidence 
that high-flow samplers, in particular the GK2.69 cyclone, can be used 
to collect respirable crystalline silica air samples in most workplace 
settings without introducing undue bias.
    Mr. Scott, testifying for the ACC, was of the opinion that, 
although high-flow samplers have been evaluated by Gorner et al. (2001, 
Document ID 1457) and Lee et al. (2010, Document ID 3616; 2012, 3615) 
with respect to their sampling efficiencies as compared to the ISO/CEN 
convention and their performance compared to low-flow samplers, none of 
the studies evaluated the accuracy and precision using methods 
recommended in NIOSH's Guidelines for Air Sampling and Analytical 
Method Development and Evaluation (1995, http://www.cdc.gov/niosh/docs/95-117/) (Document ID 2308, Attachment 6, p. 18). OSHA understands Mr. 
Scott to contend that the sampler must be tested against a generated 
atmosphere of respirable crystalline silica and that the precision of 
the sampling and analytical method must be determined overall from 
these generated samples.
    OSHA does not agree with the implication that, until high-flow 
samplers have been evaluated according to the NIOSH (1995) protocol, 
the findings from the studies described above are not sufficient to 
permit an assessment of sampler performance. The NIOSH Guidelines cited 
by Mr. Scott state that ``[a]n experimental design for the evaluation 
of sampling and analytical methods has been suggested. If these 
experiments are not applicable to the method under study, then a 
revised experimental design should be prepared which is appropriate to 
fully evaluate the method'' (http://www.cdc.gov/niosh/docs/95-117/, p. 
1). These guidelines contemplate the development of entirely new 
sampling and analytical methods. Because the analytical portion of the 
sampling and analytical method for respirable crystalline silica was 
already fully evaluated before the GK2.69 was developed (Kenny and 
Gussman, 1997, Document ID 1444), it was only necessary to evaluate the 
performance of the GK2.69 high-flow sampler. As described above, the 
studies by Lee et al. (2010, Document ID 3616; 2012, 3615) and Stacey 
et al. (2013, Document ID 3618) reflect a collaborative effort between 
NIOSH in the U.S. and HSE in the U.K. to evaluate the performance of 
high-flow respirable dust samplers. The Lee et al. (2010, 2012) studies 
were conducted by NIOSH laboratories in Morgantown, West Virginia with 
peer review by HSE scientists, and the Stacey et al. (2013) study was 
conducted by HSE at the Health and Safety Laboratory at Buxton in the 
U.K. Both Lee et al. (2012) and Stacey et al. (2013) concluded that 
high-flow samplers studied, including the GK2.69, met the EN 13205 
requirements for accuracy for sampling against the ISO/CEN convention, 
demonstrating that results from these two national laboratories 
compared favorably. OSHA concludes these peer-reviewed studies, 
performed by NIOSH and HSE scientists, meet the highest standards for 
effective methods evaluation and therefore does not agree with the 
suggestion that additional work following NIOSH's protocol is 
necessary. Comments submitted by NIOSH indicate that the Lee et al. 
(2010, 2012) and Stacy et al. (2013) studies are

[[Page 16445]]

sufficient to establish the GK2.69 high-flow sampler as acceptable for 
sampling respirable crystalline silica under the ISO/CEN convention 
(Document ID 2177, Attachment B; 4233, p. 4).
    URS Corporation, on behalf of the ACC, commented that precision 
will not be improved by the use of high-flow samplers because filter 
loadings of interferences will increase along with the amount of 
crystalline silica; this would, in URS's opinion, necessitate 
additional sample handling procedures, such as acid washing, that erode 
precision. URS also argued that such samples may require analysis of 
multiple peaks and that overall X-ray intensity may be diminished due 
to increased filter load (Document ID 2307, Attachment 12, p. 3). In 
its post-hearing brief, the ACC stated that the use of high-volume 
samplers ``in addition to traditional Dorr-Oliver sampler'' would 
reduce inter-laboratory precision (i.e., the extent to which different 
laboratories achieve similar results for the same sample) due to the 
use of multiple sampler types (Document ID 4209, p. 154).
    OSHA finds that these arguments are unsupported. Although the high-
flow sampler will collect more dust than lower-flow samplers in the 
same environment, the relative proportion of any interfering materials 
collected to the amount of crystalline silica collected would remain 
unchanged. Thus, there should be no increased effect from the 
interfering materials relative to the silica. OSHA recognizes that, to 
prevent undue interference or diminished X-ray intensity, it is 
important to keep the dust load on the filter within reasonable limits. 
Both OSHA and NIOSH methods stipulate a maximum sample weight to be 
collected (3 mg for OSHA and 2 mg for NIOSH) (Document ID 0946, p. 5; 
0901, p. 3), and in the event that excess sample is collected, the 
sample can be split into portions and each portion analyzed separately 
(Document ID 0946, p. 5). In environments where using a high-flow 
sampler is likely to collect more than the maximum sample size, use of 
a lower-flow sampler is advised. In response to the concern that 
permitting use of high-flow samplers will affect inter-laboratory 
variability, OSHA observes that employers are already using a variety 
of commercially available samplers, such as those listed in the NIOSH 
Method 7500, to obtain exposure samples; not everyone uses the Dorr-
Oliver sampler. Thus, for the final rule, OSHA is permitting employers 
to use any sampling device that has been designed and calibrated to 
conform to the ISO/CEN convention, including higher-flow samplers such 
as the GK2.69. In effect, this is a continuation of well-studied 
current practice, not an untested departure from it.
b. Laboratory Analysis of Crystalline Silica
    Crystalline silica is analyzed in the laboratory using either X-ray 
diffraction (XRD) or infrared spectroscopy (IR). A third method, 
colorimetric spectrophotometry, is no longer used (Document ID 3579, 
Tr. 211; Harper et al., 2014, 3998, Attachment 8, p. 1). This section 
describes crystalline silica analysis by XRD and IR and responds to 
comments and testimony on the precision and accuracy of these methods 
for measuring crystalline silica concentrations in the range of the 
final rule's PEL and action level. As discussed below, both XRD and IR 
methods can detect and quantify crystalline silica in amounts collected 
below the final rule's 25 [micro]g action level.
X-Ray Diffraction
    For XRD, a dust sample that has been collected by a sampler is 
deposited on a silver-membrane filter and scanned by the X-ray beam, 
where X-rays diffract at specific angles. A sensor detects these 
diffracted X-ray beams and records each diffracted beam as a 
diffraction peak. Unique X-ray diffraction patterns are created when 
the diffraction peaks are plotted against the angles at which they 
occur. The intensity of the diffracted X-ray beams depends on the 
amount of crystalline silica present in the sample, which can be 
quantified by comparing the areas of the diffraction peaks obtained 
with those obtained from scanning a series of calibration standards 
prepared with known quantities of an appropriate reference material. 
Comparing multiple diffraction peaks obtained from the sample with 
those obtained from the calibration standards permits both quantitative 
and qualitative confirmation of the amount and type of crystalline 
silica present in the sample (i.e., quartz or cristobalite). A major 
advantage of XRD compared with the other techniques used to measure 
crystalline silica is that X-ray diffraction is specific for 
crystalline materials. Neither non-crystalline silica nor the amorphous 
silica layer that forms on crystalline silica particles affects the 
analysis. The ability of this technique to quantitatively discriminate 
between different forms of crystalline silica and other crystalline or 
non-crystalline materials present in the sample makes this method least 
prone to interferences. Sample analysis by XRD is also non-destructive, 
meaning that samples can be reanalyzed if necessary (Document ID 1720, 
pp. IV-26--IV-27).
    The OSHA Technical Manual lists the following substances as 
potential interferences for the analysis of crystalline silica using 
XRD: Aluminum phosphate, feldspars (microcline, orthoclase, 
plagioclase), graphite, iron carbide, lead sulfate, micas (biotite, 
muscovite), montmorillonite, potash, sillimanite, silver chloride, 
talc, and zircon (https://www.osha.gov/dts/osta/otm/otm_ii/otm_ii_1.html, Chapter 1, III.K). The interference from other minerals 
usually can be recognized by scanning multiple diffraction peaks 
quantitatively. Diffraction peak-profiling techniques can resolve and 
discriminate closely spaced peaks that might interfere with each other. 
Sometimes interferences cannot be directly resolved using these 
techniques. However, many interfering materials can be chemically 
washed away in acids that do not dissolve the crystalline silica in the 
sample. Properly performed, these acid washes can dissolve and remove 
these interferences without appreciable loss of crystalline silica 
(Document ID 1720, p. IV-27).
    The nationally recognized analytical methods using XRD include OSHA 
ID-142, NIOSH 7500, and MSHA P-2 (Document ID 0946; 0901; 1458). All 
are based on the XRD of a redeposited thin-layered sample with 
comparison to standards of known concentrations (Document ID 0946, p. 
1; 0901, p. 1; 1458, p. 1). These methods, however, differ on 
diffraction peak confirmation strategies. The OSHA and MSHA methods 
require at least three diffraction peaks to be scanned (Document ID 
0946, p. 5; 1458, p. 13). The NIOSH method only requires that multiple 
peaks be qualitatively scanned on representative bulk samples to 
determine the presence of crystalline silica and possible 
interferences, and quantitative analysis of air samples is based on a 
single diffraction peak for each crystalline silica polymorph analyzed 
(Document ID 0901, pp. 3, 5).
Infrared Spectroscopy
    Infrared spectroscopy is based on the principle that molecules of a 
material will absorb specific wavelengths of infrared electromagnetic 
energy that match the resonance frequencies of the vibrations and 
rotations of the electron bonds between the atoms making up the 
material. The absorption of IR radiation by the sample is compared with 
the IR absorption of calibration standards of known concentration to 
determine the amount of crystalline silica in the sample. Using IR can 
be efficient for routine analysis of samples that are well

[[Page 16446]]

characterized with respect to mineral content, and the technique, like 
XRD, is non-destructive, allowing samples to be reanalyzed if 
necessary. The three principle IR analytical methods for crystalline 
silica analyses are NIOSH 7602 (Document ID 0903), NIOSH 7603 (http://www.cdc.gov/niosh/docs/2003-54/pdfs/7603.pdf), and MSHA P-7 (Document 
ID 1462); NIOSH Method 7603 and MSHA P-7 were both specifically 
developed for the analysis of quartz in respirable coal dust. OSHA does 
not use IR for analysis of respirable crystalline silica.
    Interferences from silicates and other minerals can affect the 
accuracy of IR results. The electromagnetic radiation absorbed by 
silica in the infrared wavelengths consists of broad bands. In theory, 
no two compounds have the same absorption bands; however, in actuality, 
the IR spectra of silicate minerals contain silica tetrahedra and have 
absorption bands that will overlap. If interferences enhance the 
baseline measurement and are not taken into account, they can have a 
negative effect that might underestimate the amount of silica in the 
sample. Compared with XRD, the ability to compensate for these 
interferences is limited (Document ID 1720, pp. IV-29--IV-30).
c. Sensitivity of Sampling and Analytical Methods
    The sensitivity of an analytical method or instrument refers to the 
smallest quantity of a substance that can be measured with a specified 
level of accuracy, and is expressed as either the LOD or the ``Limit of 
Quantification'' (LOQ). These two terms have different meanings. The 
LOD is the smallest amount of an analyte that can be detected with 
acceptable confidence that the instrument response is due to the 
presence of the analyte. The LOQ is the lowest amount of analyte that 
can be reliably quantified in a sample and is higher than the LOD. 
These values can vary from laboratory to laboratory as well as within a 
given laboratory between batches of samples because of variation in 
instrumentation, sample preparation techniques, and the sample matrix, 
and must be confirmed periodically by laboratories.
    At a concentration of 50 [micro]g/m\3\, the final rule's PEL, the 
mass of crystalline silica collected on a full-shift (480 minute) air 
sample at a flow rate of 1.7 L/min, for a total of 816 L of air, is 
approximately 41 [micro]g (see Table VII-7). At a concentration of 25 
[micro]g/m\3\, the final rule's action level, the mass collected is 
about 20 [micro]g. The LOQ for quartz for OSHA's XRD method is 10 
[micro]g (Document ID 0946; 3764, p. 4), which is below the amount of 
quartz that would be collected from full-shift samples at the PEL and 
action level. Similarly, the reported LODs for quartz for the NIOSH and 
MSHA XRD and IR methods are lower than that which would be collected 
from full-shift samples taken at the PEL and action level (NIOSH Method 
7500, Document ID 0901, p. 1; MSHA Method P-2, 1458, p. 2; NIOSH Method 
7602, 0903, p. 1; NIOSH Method 7603, http://www.cdc.gov/niosh/docs/2003-154/pdfs/7603.pdf, p. 1; MSHA Method P-7, 1462, p. 1).
    The rule's 50 [micro]g/m\3\ PEL for crystalline silica includes 
quartz, cristobalite, and tridymite in any combination. For 
cristobalite and tridymite, the previous general industry formula PEL 
was approximately 50 [micro]g/m\3\, so the change in the PEL for 
crystalline silica does not represent a substantive change in the PEL 
for cristobalite or tridymite when quartz is not present. OSHA Method 
ID-142 (Document ID 0946) lists a 30-[micro]g LOQ for cristobalite; 
however, because of technological improvements in the equipment, the 
current LOQ for cristobalite for OSHA's XRD method as implemented by 
the OSHA Salt Lake Technical Center (SLTC) is about 20 [micro]g 
(Document ID 3764, p. 10).
    That XRD analysis of quartz from samples prepared from reference 
materials can achieve LODs and LOQs between 5 and 10 [micro]g was not 
disputed in the record. Of greater concern to several rulemaking 
participants was the effect of interfering materials potentially 
present in a field sample on detection limits and on the accuracy of 
analytical methods at low filter loads when interferences are present. 
Although the Chamber's witness, Robert Lieckfield of Bureau Veritas 
Laboratories, did not dispute that laboratories could achieve this 
level of sensitivity (Document ID 3576, Tr. 485-486), the ACC took 
issue with this characterization of method sensitivity stating that 
``the LOQ for real world samples containing interferences is likely to 
be higher than the stated LOQ's for analytical methods, which are 
determined using pure NIST samples with no interferences'' (Document ID 
4209, p. 132). Both Mr. Lieckfield and Mr. Scott testified that the 
presence of interferences in samples can increase the LOQ and potential 
error of measurement at the LOQ (Document ID 2259, p. 7; 3460, p. 5).
    Mr. Scott (Document ID 2308, Attachment 6, p. 5) cited a laboratory 
performance study by Eller et al. (1999a, Document ID 1687), in which 
laboratories analyzing samples with and without interfering materials 
present reported a range of LOD's from 5 [mu]g to 50 [mu]g. Mr. Scott 
believed that this study provided evidence that interfering materials 
present in crystalline silica samples adversely affected laboratories' 
reported LODs. OSHA disagrees with this interpretation. The Agency 
reviewed this study in the PEA (Document ID 1720, p. IV-33) and 
believes that the variability in reported LODs reflected differences in 
laboratory practices with respect to instrument calibration and quality 
control procedures. These factors led Eller et al. (1999b, Document ID 
1688, p. 24; 1720, p. IV-42) to recommend changes in such practices to 
improve laboratory performance. Thus, OSHA finds that the variation in 
reported LODs referred to by Mr. Scott cannot be attributed primarily 
to the presence of interfering materials on the samples.
    The presence of interferences can adversely affect the sensitivity 
and precision of the analysis, but typically only when the interference 
is so severe that quantification of crystalline silica must be made 
from secondary and tertiary diffraction peaks (Document ID 0946, p. 6). 
However, OSHA finds no evidence that interferences usually present 
serious quantification problems. First, there are standard protocols in 
the OSHA, NIOSH, and MSHA methods that deal with interferences. 
According to OSHA Method ID-142,

Because of these broad selection criteria and the high specificity 
of the method for quartz, some of the listed interferences may only 
present a problem when a large amount of interferent is present. . . 
. Interference effects are minimized by analyzing each sample for 
confirmation using at least three different diffraction peaks so as 
to include peaks where the quartz and cristobalite results are in 
good agreement and where the interferent thus causes no problem. 
Bulk samples or a description of the process being sampled are 
useful in customizing a chemical cleanup procedure for any 
interference found difficult to resolve by software. Even so, the 
presence of an interference rarely jeopardizes the analysis 
(Document ID 0946, p. 5).

    Software developed by instrument manufacturers and techniques such 
as acid washing of the sample when interferences are suspected to be 
present are also useful in resolving interferences. The Chamber's 
expert witness, Mr. Lieckfield, acknowledged that it was also their 
practice at his lab to chemically treat samples from the start to 
remove interfering materials and to analyze multiple diffraction peaks 
to resolve interferences (Document ID 3576, Tr. 533, 542). According to 
OSHA's representative from the SLTC, it is ``nearly always possible'' 
to eliminate interferences and is it no more difficult to obtain 
precise measurements when

[[Page 16447]]

interferences are present than when they are not (Document ID 3579, Tr. 
48).
    ACC also cites the results of a round-robin performance study that 
it commissioned, in which five laboratories were provided with 
crystalline silica samples with and without interfering materials 
(Document ID 4209, p. 132). These laboratories reported non-detectable 
levels of silica for 34 percent of the filters having silica loadings 
of 20 [mu]g or more. However, as discussed below in the section on 
inter-laboratory variability (Section IV-3.2.5--Measurement Error 
Between Laboratories), OSHA has determined that this study is seriously 
flawed and, in particular, that there was systematic bias in the 
results, possibly due to sample loss. This could explain the high 
prevalence of reported non-detectable samples by the laboratories, 
rather than the presence of interferences per se.
    Furthermore, OSHA's review of the several hundred inspection 
reports relied on to evaluate the technological feasibility of the 
final rule's PEL in many industry sectors does not show that 
investigators have particular difficulty in measuring respirable 
crystalline silica concentrations below the PEL. Sections IV-4 and IV-5 
of this chapter contain hundreds of exposure measurement results in a 
wide variety of workplace settings that were detected and reported by a 
laboratory as being above detectable limits but below the PEL or action 
level. If, as ACC suggests, interferences have a profound effect on the 
ability to measure concentrations in this range, many of these samples 
might have been reported as ``less than the LOD,'' with the reported 
LOD in the range of 25 [mu]g to 50 [mu]g. Examination of the exposure 
data described in Sections IV-4 and IV-5 of this chapter shows clearly 
that this is not the case (see exposure profiles for Concrete Products, 
Section IV-4.3; Cut Stone, Section IV-4.4; Foundries (Metal Casting), 
Section IV-4.8; Mineral Processing, Section IV-4.12; Porcelain 
Enameling, Section IV-4.14; Ready Mix Concrete, Section IV-4.17; 
Refractories, Section IV-4.18). In addition, the United Steelworkers 
reported receiving exposure data from 17 employers with samples in this 
same range, indicating that sampling of exposures below the final PEL 
and action level is feasible and already being utilized by employers 
(Document ID 4214, pp. 12-13; Document ID 4032, Attachment 3).
    Therefore, OSHA finds that the presence of interfering substances 
on field samples will not, most of the time, preclude being able to 
detect concentrations of respirable crystalline silica in the range of 
the PEL and action level, and that such instances where this might 
occur are rare. Accordingly, even when the presence of interfering 
substances is taken into account, worker exposure is capable of being 
measured with a reasonable degree of sensitivity and precision.
d. Precision of Measurement
    All analytical methods have some random measurement error. The 
statistics that describe analytical error refer to the amount of random 
variation in measurements of replicate sets of samples containing the 
same quantity of silica. This variation is expressed as a standard 
deviation about the mean of the measurements. The relative standard 
deviation (RSD), a key statistic used to describe analytical error, is 
calculated by dividing the standard deviation by the mean for a data 
set. The RSD is also known as the coefficient of variation (CV).
    When random errors are normally distributed, a 95-percent 
confidence interval can be calculated as X  (1.96 x CV), 
where X is the mean. This statistic is termed the ``precision'' of the 
analytical method and represents a 2-sided confidence interval in that, 
for a particular measurement, there is a 95-percent chance that the 
``true'' value, which could be higher or lower than the measurement, 
lies within the confidence interval. The measure of analytical 
precision typically also includes a term to represent error in sampler 
pump flow, which is conventionally taken to be 5 percent. The better 
the precision of an analytical method, the lower its value (i.e., a 
method having a precision of 17 percent has better precision than one 
with a precision of 20 percent).
    OSHA also uses a statistic called the Sampling and Analytical Error 
(SAE) to assist compliance safety and health officers (CSHOs) in 
determining compliance with an exposure limit. The estimate of the SAE 
is unique for each analyte and analytical method, and must be 
determined by each laboratory based on its own quality control 
practices. At OSHA's Salt Lake Technical Center (SLTC), where 
analytical methods are developed and air samples taken for enforcement 
purposes are analyzed, the SAE is based on statistical analysis of 
results of internally prepared quality control samples. Sampling and 
analytical components are assessed separately, where CV1 
reflects analytical error that is estimated from the analysis of 
quality control samples, and CV2 is the sampling error, 
assumed to be 5 percent due to variability in sampling pump flow rates 
that can affect sample air volume. Analytical error is combined with 
sampling pump error, and the SAE is calculated as a one-sided 95-
percent confidence limit with the following formula:

[GRAPHIC] [TIFF OMITTED] TR25MR16.178

    The current SLTC SAE for crystalline silica is approximately 0.17, 
according to testimony from a representative of SLTC (Document ID 3579, 
Tr. 95). OSHA uses the SAE in its enforcement of PELs, where the PEL 
times the SAE is added to the PEL for a substance and compared to a 
sample result (see Section II, Chapter 1 of the OSHA Technical Manual, 
https://www.osha.gov/dts/osta/otm/otm_toc.html). A sample result is 
considered to have definitively exceeded the PEL if the result is 
greater than the sum of the PEL and the PEL times the SAE. For example, 
with the PEL at 50 [mu]g/m\3\ and an SAE of 17 percent, an air sample 
result would have to be greater than 58.5 [mu]g/m\3\ (i.e., 50 + (50 x 
0.17)) to be considered to have definitively exceeded the PEL. This 
policy gives employers the benefit of the doubt, as it assumes that the 
actual exposure was below the PEL even when the result is above the PEL 
but below the PEL plus the SAE; the effect is that OSHA does not cite 
an employer for an exposure above the PEL unless the Agency has 
obtained a sample measurement definitively above the PEL after 
accounting for sampling and analytical error.
    OSHA's quality control samples, which were prepared and analyzed at 
SLTC, demonstrate that the XRD method has acceptable precision, even at 
the low range of filter loads (50 [mu]g). For the period April 2012 
through April 2014, SLTC's analysis of 348 quality control samples, 
with a range of filter loads of about 50 to 250 [mu]g crystalline 
silica, showed average recovery (i.e., the measurement result as 
compared to the reference mean value for the sample) of 0.98 with an 
RSD of 0.093 and precision of 20.8 percent (Document ID 3764, 
Attachment 1). Among those samples, there were 114 with a target filter 
load of 50 [mu]g (range of actual filter load was 50 to 51.6 [mu]g); 
these samples showed an average recovery of 1.00 with an RSD of 0.093 
and precision of 20.7 percent (Document ID 3764, Attachment 1). Thus, 
OSHA's experience with quality control standards shows that the XRD 
method for quartz is as precise in the low range of method validation 
as it is over the full range.
    The ACC raised several questions regarding OSHA's Method ID-142 and

[[Page 16448]]

its validation. First, a paper they submitted by Sandra Wroblewski, 
CIH, of Computer Analytical Solutions notes that OSHA's stated Overall 
Analytical Error is 26 percent, higher than the 25-percent level ``OSHA 
states is necessary to ensure that a PEL can be feasibly measured,'' 
and that the method had not been validated for cristobalite (Document 
ID 2307, Attachment 10, pp. 13-14). In addition, the ACC stated that 
OSHA's method specifies a precision and accuracy validation range of 
50-160 [micro]g quartz per sample, above the quantity that would be 
collected at the PEL and action level (assuming use of a Dorr-Oliver 
sampler at 1.7 L/min) and that the method has not been tested for 
validation at a range corresponding to the PEL and action level 
(Document ID 2307, Attachment 10, p. 14). ACC also argued that OSHA's 
method does not comply with the Agency's Inorganic Methods Protocol, 
which requires the CV1 to be 0.07 or less and the detection 
limit to be less than 0.1 times the PEL (Document ID 2307, Attachment 
A, p. 202). The Edison Electric Institute (Document ID 2357, pp. 20-21) 
and Ameren Corporation (Document ID 2315, p. 2) expressed similar 
concerns about the detection limit.
    While OSHA's published Method ID-142 reports an Overall Analytical 
Error of 26 percent, OSHA no longer uses this statistic (it is in the 
process of revising Method ID-142); the Agency provides measures of 
precision and SAE instead. The Overall Analytical Error, which is 
described in Method ID-142, published in 1996, included a bias term 
that is now corrected for in the data used to determine method 
precision, so there is no longer a need to include a bias term in the 
estimation of analytical error. As described above, the precision of 
Method ID-142 is about 21 percent based on recent quality control 
samples.\24\ OSHA's Inorganic Methods Protocol, to which the ACC 
referred, has been replaced by evaluation guidelines for air sampling 
methods using spectroscopic or chromatographic analysis, published in 
2005 (https://www.osha.gov/dts/sltc/methods/spectroguide/spectroguide.html) and 2010 (https://www.osha.gov/dts/sltc/methods/chromguide/chromguide.html), respectively. These more recent 
publications no longer reflect the guidance contained in the Inorganic 
Methods Protocol, and OSHA's Method ID-142 is consistent with these 
more recent guidelines. Finally, although the published method did not 
include validation data for filter loads below 50 [mu]g or data for 
cristobalite, OSHA has conducted studies to characterize the precision 
that is achieved at low filter loads for quartz and cristobalite; these 
studies are in the rulemaking record (Document ID 1670, Attachment 1; 
1847, Attachment 1; 3764, pp. 15-16) and are discussed further below.
---------------------------------------------------------------------------

    \24\ OSHA also wishes to point out that the guideline for 
achieving a method precision of 25 percent was never an OSHA 
requirement for determining method feasibility, but is drawn from 
the NIOSH Accuracy Criterion (http://www.cdc.gov/niosh/docs/95-117/
), which was used for the purpose of developing and evaluating 
analytical methods. Nevertheless, OSHA's Method ID-142 now meets 
that guideline.
---------------------------------------------------------------------------

    In comments submitted on behalf of the Chamber, Mr. Lieckfield 
cited the NIOSH Manual of Analytical Methods, Chapter R, as stating 
that ``current analysis methods do not have sufficient accuracy to 
monitor below current exposure standards'' (Document ID 2259, p. 1). 
However, this is contradicted by NIOSH's own post-hearing submission, 
which stated that, although method variability was assessed based on 
the exposure limits at that time (i.e., 1983, see Document ID 0901, pp. 
1, 7), ``it was known from an intra-laboratory study that an acceptable 
variability would likely be at least 20 [mu]g on-filter, and so 20 
[mu]g was given as the lower range of the analytical method'' (Document 
ID 4233, p. 3). Furthermore, in Chapter R of NIOSH's Manual, NIOSH goes 
on to say that the GK2.69 high-flow sampler ``has promise for 
potentially lowering the levels of silica that can be measured and 
still meet the required accuracy'' (http://www.cdc.gov/niosh/docs/2003-154/pdfs/chapter-r.pdf, p. 265). This chapter was published in 2003, 
well before the studies by Lee et al. (2010, 2012) and Stacey et al. 
(2013), discussed above, which demonstrate that the GK2.69 sampler has 
acceptable performance. NIOSH concluded in its post-hearing comment 
that ``current methods of sampling and analysis for respirable 
crystalline silica have variability that is acceptable to demonstrate 
compliance with the proposed PEL and action level'' (Document ID 4233, 
p. 4).
    At the time of the proposal, there was little data characterizing 
the precision of analytical methods for crystalline silica at filter 
loads in the range of the PEL and action level (i.e., with prepared 
samples of 40 [mu]g and 20 [mu]g crystalline silica, which are the 
amounts of silica that would be collected from full-shift sampling at 
the PEL and action level, respectively, assuming samples are collected 
with a Dorr-Oliver cyclone at a flow rate of 1.7 L/min). To 
characterize the precision of OSHA's Method ID-142 at low filter loads, 
SLTC conducted studies in 2010 and again in 2013 (the latter of which 
was presented in the PEA; see Document ID 1720, p. IV-35). For these 
studies, the lab prepared 10 replicate samples each of quartz and 
cristobalite from NIST standard reference material and determined the 
precision of the analytical method; a term representing pump flow rate 
error was included in the precision estimate. In the 2010 test 
(Document ID 1670, Attachment 1), the precision for quartz loads 
equating to the PEL and action level was 27 and 33 percent, 
respectively. For cristobalite loads equating to the PEL and action 
level, the precision was 23 and 27 percent, respectively. The results 
from the 2013 test (Document ID 1847, Attachment 1; 3764, pp. 15-16; 
Document ID 1720, p. IV-35) showed improvement in the precision; for 
quartz, precision at loads equating to the PEL and action level was 17 
and 19 percent, respectively, and for cristobalite, precision at loads 
equating to the PEL and action level was 19 and 19 percent, 
respectively. Both the 2010 and 2013 tests were conducted using the 
same NIST standards, same instrumentation, and same sample preparation 
method (OSHA Method ID-142) with the exception that the 2013 test used 
automatic pipetting rather than manual pipetting to prepare the samples 
(Document ID 1847). OSHA believes it likely that this change in sample 
preparation reduced variation in the amount of silica loaded onto the 
filters, which would account for at least some of the increased 
precision seen between 2010 and 2013 (i.e., imprecision in preparing 
the samples would make the analytical precision for 2010 appear worse 
than it actually was). Based on these studies, particularly the 2013 
study, OSHA preliminarily determined that the XRD method was capable of 
accurately measuring crystalline silica concentrations at the PEL and 
action level.
    The ACC believed that OSHA's reliance on the 2013 study was 
``misplaced'' because the results were not representative of ``real 
world'' samples that contain interfering minerals that could increase 
analytical error, and because the studies did not account for inter-
laboratory variability (Document ID 4209, pp. 135-137; 2308, Attachment 
6, p. 10). The ACC also believed that variability would have been 
depressed in this study because the samples were analyzed in close 
temporal proximity by the same analyst and using the same instrument 
calibration, and the study involved only 10 samples at each filter load 
(Document ID 4209, pp. 137-138; 2308,

[[Page 16449]]

Attachment 6, p. 10). The ACC's witness, Mr. Scott, also commented that 
the study failed to take into account the effect of particle sizes on 
the analysis of crystalline silica and believed that SLTC's evaluation 
could not reflect differences in precision between the XRD and IR 
methods (Document ID 2308, Attachment 6, p. 10).
    Despite the criticism that OSHA's investigation involved a small 
number of samples analyzed at the same time, the results obtained were 
comparable to OSHA's analysis of quality control samples at somewhat 
higher filter loads (between 50 and 51.6 [mu]g) analyzed over a two-
year period (Document ID 3764, Attachment 1). These results, described 
above, showed a precision of 20.7 percent, compared to 17 and 19 
percent for quartz filter loads of 40 and 20 [mu]g, respectively 
(Document ID 1847, Attachment 1; Document ID 3764). From these results, 
OSHA concludes that any effect on analytical error from performing a 
single study using the same analyst and instrument calibration is 
modest.
    OSHA also concludes that Mr. Scott's argument that particle size 
effects were not taken into account is without merit. The samples 
prepared and analyzed in OSHA's study, like any laboratory's quality 
control samples, use standard materials that have a narrow range in 
particle size. Although large (non-respirable) size particles can 
result in an overestimate of crystalline silica content, in practice 
this is not typically a serious problem with air samples and is more of 
a concern with analyzing bulk samples. First, as discussed above, 
respirable dust samplers calibrated to conform to the ISO/CEN 
convention are collecting respirable particulate and excluding larger 
particles (Document ID 3579, Tr. 219). In analyzing field samples, OSHA 
uses microscopy to identify whether larger particles are present and, 
if they are, the results are reported as a bulk sample result so as not 
to be interpreted as an airborne exposure (Document ID 3579, Tr. 213). 
Additionally, OSHA's Method ID-142 calls for grinding and sieving bulk 
samples to minimize particle size effects in the analysis (Document ID 
0946, p. 13). OSHA also notes that the Chamber's witness, Mr. 
Lieckfield, testified that his laboratory does not check for oversized 
particles (Document ID 3576, p. 483).
    With regard to interferences, as discussed above, there are 
procedures that have been in place for many years to reduce the effect 
of interfering materials in the analysis. The presence of interferences 
does not typically prevent an analyst from quantifying crystalline 
silica in a sample with reasonable precision. As to the claim regarding 
XRD versus IR, a recent study of proficiency test data, in which 
multiple laboratories are provided comparable silica samples, both with 
and without interfering materials added, did not find a meaningful 
difference in precision between laboratories using XRD and those using 
IR (Harper et al., 2014, Document ID 3998, Attachment 8). In addition, 
as discussed above, NIOSH's and OSHA's measures of precision of the XRD 
method at low filter loads were comparable, despite differences in 
equipment and sample preparation procedures. Therefore, OSHA finds that 
the studies it carried out to evaluate the precision of OSHA Method ID-
142 at low filter loads provide a reasonable characterization of the 
precision of the method for analyzing air samples taken at 
concentrations equal to the final PEL and action level under the 
respirable crystalline silica rule.
    With respect to the ACC's and Mr. Scott's reference to inter-
laboratory variation in silica sample results, OSHA discusses data and 
studies that have evaluated inter-laboratory variance in analytical 
results in the next section.
e. Measurement Error Between Laboratories
    The sources of random and systematic error described above reflect 
the variation in sample measurement experienced by a single laboratory; 
this is termed intra-laboratory variability. Another source of error 
that affects the reliability of results obtained from sampling and 
analytical methods is inter-laboratory variability, which describes the 
extent to which different laboratories may obtain disparate results 
from analyzing the same sample. Inter-laboratory variability can be 
characterized by using data from proficiency testing, where 
laboratories analyze similarly-prepared samples and their results are 
compared. In practice, however, it is difficult to separate intra- and 
inter-laboratory variability because each laboratory participating in a 
proficiency test provides analytical results that reflect their own 
degree of intra-laboratory variability. Thus, use of proficiency test 
data to compare performance of laboratories in implementing an 
analytical method is really a measure of total laboratory variability.
    The best available source of data for characterizing total 
variability (which includes an inter-laboratory variability component) 
of crystalline silica analytical methods is the AIHA Industrial Hygiene 
Proficiency Analytical Testing (PAT) Program. The AIHA PAT Program is a 
comprehensive testing program that provides an opportunity for 
laboratories to demonstrate competence in their ability to accurately 
analyze air samples through comparisons with other labs. The PAT 
program is designed to help consumers identify laboratories that are 
deemed proficient in crystalline silica analysis.
    Crystalline silica (using quartz only) is one of the analytes 
included in the proficiency testing program. The AIHA PAT program 
evaluates the total variability among participating laboratories based 
on proficiency testing of specially prepared silica samples. The AIHA 
contracts the preparation of its crystalline silica PAT samples to an 
independent laboratory that prepares four PAT samples in the range of 
about 50 to 225 [mu]g (Document ID 3586, Tr. 3279-3280) and one blank 
sample for each participating laboratory per round. Each set of PAT 
samples with the same sample number is prepared with as close to the 
same mass of crystalline silica deposited on the filter as possible. 
However, some variability occurs within each numbered PAT sample set 
because of small amounts of random error during sample preparation. 
Before the contract laboratory distributes the round, it analyzes a 
representative lot of each numbered set of samples to ensure that 
prepared samples are within 10 percent (Document ID 3586, 
Tr. 3276). The samples are distributed to the participating 
laboratories on a quarterly basis (Document ID 1720, p. IV-36). The PAT 
program does not specify the particular analytical method to be used. 
However, the laboratory is expected to analyze the PAT samples using 
the methods and procedures it would use for normal operations.
    The results of the PAT sample analysis are reported to the AIHA by 
the participating laboratories. For each PAT round, AIHA compiles the 
results and establishes upper and lower performance limits for each of 
the four sample results based on the mean and RSD of the sample 
results. For each of the four samples, a reference value is defined as 
the mean value from a selected set of reference laboratories. The RSD 
for each of the four samples is determined from the results reported by 
the reference labs after correcting for outliers (generally clear 
mistakes in analysis or reporting, particularly those that are order-
of-magnitude errors) (Document ID 4188, p. 2). A participating 
laboratory receives a passing score if at least three out of the four 
sample results reported are within 20 percent of the reference mean for 
the sample (Document ID 3586, Tr. 3291).

[[Page 16450]]

Two or more results reported by a lab in a given round that are outside 
the limits results in the lab receiving an unsatisfactory rating. An 
unsatisfactory rating in 2 of the last 3 rounds results in revocation 
of the lab's AIHA accreditation for the analysis of crystalline silica. 
Participation in the PAT program is a prerequisite for accreditation 
through the AIHA Industrial Hygiene Laboratory Accreditation Program 
(IHLAP).
    In the PEA, OSHA presented PAT results from its SLTC for the period 
June 2005 through February 2010 (PAT Rounds 160-180) (Document ID 1720, 
pp. IV-40-41). The mean recovery was 99 percent, with a range of 55 to 
165 percent. Eighty-one percent of the samples analyzed over this 
period were within 25 percent of the reference mean and the 
RSD for this set of samples was 19 percent, showing reasonable 
agreement with the reference mean. OSHA also evaluated PAT data from 
all participating laboratories for the period April 2004 through June 
2006 (PAT Rounds 156-165) (Document ID 1720, pp. IV-37--IV-40). 
Overall, the mean lab RSD was 19.5 percent for the sample range of 49 
to 165 [mu]g. Beginning with Round 161, PAT samples were prepared by 
liquid deposition rather than by sampling a generated silica aerosol, 
in order to improve consistency and reduce errors in sample 
preparation. The improvement was reflected in the results, with the 
mean lab RSD declining from 21.5 percent to 17.2 percent after the 
change to liquid deposition, demonstrating the improved consistency 
between PAT samples.
    In the time since OSHA analyzed the PAT data, Harper et al. (2014, 
Document ID 3998, Attachment 8) evaluated more recent data. 
Specifically, Harper et al. (2014, Document ID 3998, Attachment 8, p. 
3) evaluated PAT test results for the period 2003-2014 (Rounds 152 
through 194) and found that variation in respirable crystalline silica 
analysis has improved substantially since the earlier data from 1990 to 
1998 was studied by Eller et al. (1999a, Document ID 1687). A total of 
9,449 sample results were analyzed after removing re-test results, 
results where the method of analysis was not identified, and results 
that were more than three standard deviations from the reference mean. 
There was a clear improvement in overall variation in the newer data 
set compared with that of Eller et al. (1999a, Document ID 1687), with 
the mean laboratory RSD declining from about 28.7 percent to 20.9 
percent (Document ID 3998, Attachment 8, Figure 1). Both the older and 
newer data sets showed that analytical variation increased with lower 
filter loadings, but the more recent data set showed a much smaller 
increase than did the older. At a filter load of 50 [mu]g, the mean lab 
RSD of the more recent data was less than 25 percent, whereas it was 
almost 35 percent with the older data set (Document ID 3998, Attachment 
8, Figure 1). It was also clear that the change in sample preparation 
procedure (i.e., from aerosol deposition to liquid deposition starting 
in Round 161) explained at least some of the improvement seen in the 
more recent PAT results, with the mean lab RSD declining from 23.6 
percent for all rounds combined to 19.9 percent for Rounds 162-194.
    Despite the improvement seen with the change in deposition method, 
it is important to understand that the observed variation in PAT 
results between labs still reflects some sample preparation error 
(limited to 10 percent as explained above), a source of 
error not reflected in the analysis of field samples. Other factors 
identified by the investigators that account for the improved 
performance include the phasing out of the colorimetric method among 
participating labs, use of more appropriate calibration materials 
(i.e., NIST standard reference material), calibration to lower mass 
loadings, stricter adherence to published method procedures, and 
possible improvements in analytical equipment. There was also only a 
small difference (2 percent) in mean lab RSD between labs using XRD and 
those using IR (Document ID 3998, Attachment 8, p. 9). The increase in 
variance seen with lower filter loads was not affected either by 
analytical method (XRD vs. IR) or by the composition of interfering 
minerals added to the matrix (Document ID 3998, Attachment 8, p. 4).
    OSHA finds that this study provides substantial evidence that 
employers will obtain reliable results from analysis of respirable 
crystalline silica most of the time for the purpose of evaluating 
compliance with the PEL. From Round 162 through 194 (after the 
deposition method was changed), and over the full range of PAT data, 
only about 7 out of the 128 (5 percent) lab RSD values reported were 
above 25 percent (Document ID 3404, Figure 2). For filter loads of 75 
[mu]g or less, only 3 lab RSD values out of about 30 reported, were 
above 25 percent. As stated above, the mean RSD at a filter load of 50 
[mu]g was less than 25 percent and agreement between labs improved 
substantially compared to earlier PAT data.
    Summary data for PAT samples having a target load of less than 62.5 
[mu]g were provided by AIHA in a post-hearing comment (Document ID 
4188) and compared with the findings reported by Harper et al. (2014, 
Document ID 3998, Attachment 8). For PAT rounds 155-193 (from 1999 to 
2013), there were 15 sets of samples in the range of 41.4 to 61.8 [mu]g 
distributed to participating laboratories. Lab RSDs from results 
reported for these samples ranged from 11.2 to 26.4 percent, with an 
average RSD of 17.1 percent, just slightly above the average RSD of 
15.9 percent for all samples across the entire range of filter loads 
from those rounds. Taken together, the results of the analysis 
performed by Harper et al. (2014, Document ID 3998, Attachment 8) and 
the summary data provided by AIHA (Document ID 4188) suggest that 
sample results from participating labs will be within 25 percent of the 
crystalline silica filter load most of the time.
    In its post hearing comments, the National Stone, Sand & Gravel 
Association (NSSGA) contended that analytical laboratories cannot 
provide adequately precise and accurate results of silica samples 
(Document ID 4232). NSSGA provided a detailed analysis of low-load 
samples from the same 15 PAT rounds as examined by AIHA (Document ID 
4188) and concluded that ``employers and employees cannot rely on 
today's silica sampling and analytical industry for consistently 
accurate sample results necessary to achieve or surpass compliance 
requirements'' (Document ID 4232, p. 26). The NSSGA compared individual 
labs' sample results to the reference mean for each sample and found, 
from the AIHA PAT data, that 76-84 percent of the results were within 
25 percent of the reference mean, and the range of results reported by 
laboratories included clear outliers, ranging from zero to several-fold 
above the target filter load (Document ID 4232, p. 8, Table 1, rows 1-
6). NSSGA concluded from this that ``[i]t is of little value to 
employers that a given lab's results meet the NIOSH Accuracy Criterion 
while other labs' results cannot, particularly since employers almost 
certainly won't know which labs fall into which category'' (Document ID 
4232, p. 10). NSSGA's point appears to be that the outliers in the PAT 
data erode an employer's ability to determine if they are receiving 
accurate analytical results, without which they have little ability to 
determine their compliance status with respect to the PEL or action 
level. Further, NSSGA suggests that OSHA's analysis of the PAT data, 
discussed above, is not adequate to demonstrate the performance of an 
individual

[[Page 16451]]

laboratory that may be chosen by an employer.
    In response to NSSGA's criticism, OSHA points out that its analysis 
of the PAT data was part of its analysis of technological feasibility 
in which the Agency's legal burden is to show that employers can 
achieve compliance in most operations most of the time. It may be an 
unavoidable fact that lab results may be inaccurate some of the time, 
but that does not render the standard infeasible or unenforceable. OSHA 
contends that its analysis has satisfied that burden and nothing in the 
NSSGA's comments suggests otherwise.
    NSSGA further suggests that employers have no means of determining, 
based on a laboratory's PAT proficiency rating alone, whether that 
individual laboratory is likely to produce erroneously high or low 
results. OSHA concurs that selecting a laboratory based on 
accreditation, price, and turnaround time, as NSSGA suggests (Document 
ID 4232, p. 5), is common but may be inadequate to determine whether an 
individual laboratory is capable of producing results of consistently 
high quality. Employers and their industrial hygiene consultants can, 
and should, ask additional questions and request additional assurances 
of quality from the laboratories they consider using. For example, 
employers can ask to review the laboratory's individual PAT results 
over time, focusing on and questioning any significant outliers in the 
laboratory's results. While NSSGA suggests that the PAT results are 
treated as confidential by the AIHA-PAT program (Document ID 4232, p. 
6), there is nothing stopping a laboratory from sharing its PAT data or 
any other information related to its accreditation with their clients 
or prospective clients.
    Further, laboratories routinely perform statistical analyses of 
their performance in the context of analyzing known samples they use 
for equipment calibration, and often perform statistical comparisons 
among the various technicians they employ. Review of these statistics 
can shed light on the laboratory's ability to provide consistent 
analysis. Finally, as employers conduct exposure monitoring over time, 
and come to understand what results are typically seen in their 
workplaces, clear outliers should become more identifiable; for 
example, if employee exposures are usually between the action level and 
PEL, and a sample result shows an exposure significantly above the PEL 
without any clear change in workplace conditions or operations, 
employers should question the result and ask for a reanalysis of the 
sample. Employers could also request gravimetric analysis for 
respirable dust against which to compare the silica result to confirm 
that the silica content of the dust is consistent with past experience. 
For example, if, over time, an employer's consistent results are that 
the silica content of respirable dust generated in its workplace is 20 
percent silica, and subsequently receives a sample result that 
indicates a significantly higher or lower silica content, it would be 
appropriate for the employer to question the result and request 
reanalysis. Therefore, OSHA rejects the idea that employers are at the 
mercy of random chance and have to simply accept a high degree of 
uncertainty in exposure measurements; rather, there are positive steps 
they can take to reduce that uncertainty.
    Results from the AIHA PAT program were discussed at considerable 
length during the rulemaking proceeding. After considering all of the 
analyses of PAT data presented by Eller et al. (1999a, Document ID 
1687), OSHA in its PEA, and Harper et al. (2014, Document ID 3404), the 
ACC concluded that ``PAT program results indicate that analytical 
variability as measured by precision is unacceptably high for silica 
loadings in the range of 50-250 [mu]g'' and that the PAT data ``provide 
strong evidence that commercial laboratories will not be able to 
provide reliable measurements of . . . [respirable crystalline silica] 
exposures at the levels of the proposed PEL and action level'' 
(Document ID 4209, p. 144). OSHA disagrees with this assessment. First, 
OSHA's experience over the last 40 years in enforcing the preceding PEL 
that this standard supersedes is that analytical variability has not 
been an impediment to successful enforcement of the superseded PEL, and 
there have been few, if any, challenges to such enforcement actions 
based on variability. Nor has OSHA been made aware of concerns from 
employers that they have been unable to evaluate their own compliance 
with the former PEL or make reasonable risk management decisions to 
protect workers. In fact, the Chamber's expert, Mr. Lieckfield, 
admitted that analytical variability for asbestos, another substance 
that has been regulated by OSHA over the Agency's entire history, ``is 
worse'' than that for crystalline silica (Document ID 3576, Tr. 531).
    To support its contention that reliably measuring silica at the 
final rule's PEL and action level is not possible, the ACC cited Harper 
et al. (2014, Document ID 3998, Attachment 8) as stating that further 
increases in laboratory variance below the 40-50 [mu]g range would have 
``implications for the [working] range of the analytical methods,'' and 
that excessive variance might ``make it difficult to address for either 
method'' (Document ID 4209, p. 144). However, it is clear from Harper 
et al. (2014) that this is the basis for the authors' recommendation 
that the PAT program consider producing samples with filter loads as 
low as 20 [mu]g to ``support the analysis of lower target concentration 
levels'' (Document ID 3404, p. 5). They also identify use of currently 
available higher-flow-rate sampling devices (discussed above) to 
increase the collected mass of silica, which would generate field 
samples in the filter load range currently used in the PAT program.
    Finally, the ACC sponsored a performance testing study to assess 
inter-laboratory variability at crystalline silica filter loads at 40 
and 20 [mu]g (i.e., the amount of silica collected at final rule's PEL 
and action level, respectively, assuming use of a Dorr-Oliver cyclone 
operated at a flow rate of 1.7 L/min) as well as at 80 [mu]g (i.e., the 
amount collected at the preceding PEL) (Document ID 2307, Attachment 
14; 3461; 3462). The study was blinded in that participating 
laboratories were not aware that they were receiving prepared samples, 
nor were they aware that they were involved in a performance study. For 
this study, each of five laboratories was sent three replicate rounds 
of samples; each round consisted of three filters prepared with 
respirable crystalline silica (Min-U-Sil 5) alone, three of silica 
mixed with kaolin, three of silica mixed with soda-feldspar, and one 
blank filter. The samples were prepared by RJ Lee Group and sent by a 
third party to the laboratories as if they were field samples. All 
laboratories were accredited by AIHA and analyzed the samples by XRD.
    The samples were initially prepared on 5 [mu]m PVC filters; 
however, due to sample loss during preparation, RJ Lee changed to 0.8 
[mu]m PVC filters. It should be noted that the 2-propanol used to 
suspend the Min-U Sil sample for deposition onto the 0.8 [mu]m filter 
dissolved between 50 and 100 [mu]g of filter material, such that the 
amount of minerals deposited on the filter could not be verified from 
the post-deposition filter weights. In addition, two of the labs had 
difficulty dissolving these filters in tetrahydrofuran, a standard 
method used to dissolve PVC filters in order to redeposit the sample 
onto silver membrane filters for XRD analysis. These labs were replaced 
by two laboratories that used muffle furnaces to ash the filters before 
redeposition, as

[[Page 16452]]

did the other three labs originally selected.
    Results reported from the labs showed a high degree of both intra- 
and inter-laboratory variability as well as a systematic negative bias 
in measured vs. applied silica levels, with mean reported silica values 
more than 30 percent lower than the deposited amount. Across all 
laboratories, mean results reported for filter loads of 20, 40, and 80 
[mu]g were 13.36, 22.93, and 46.91 [mu]g, respectively (Document ID 
2307, Attachment 14, pp. 5-6). In addition, laboratories reported non-
detectable results for about one-third of the silica samples (Document 
ID 2307, Attachment 14, p. 7) and two blank filters sent to the labs 
were reported to have silica present, in one case an amount of 52 [mu]g 
(Document ID 2307, Attachment 14, pp. 9-10; 3582, Tr. 1995). Individual 
CVs for the labs ranged from 20 to 66 percent, up to more than 3 times 
higher than the CVs reported by OSHA or NIOSH for their respective 
methods. After examining variability in reported results, the 
investigators concluded that two-fold differences in filter load could 
not be reliably distinguished in the concentration range of 25 to 100 
[mu]g/m\3\ (Document ID 2307, Attachment 14, p. 14).
    OSHA identifies several deficiencies in this study; these 
deficiencies are sufficient to discredit the finding that high 
variability in silica results can be attributed to the inability of the 
analytical method to accurately measure crystalline silica at filter 
loads representative of concentrations at the action level and PEL set 
by this rule. Principally, the loss of filter material during 
deposition of the samples, combined with the lack of any verification 
of the actual amount of silica loaded onto the filters, makes it 
impossible to use the laboratory results to assess lab performance 
since the amount of silica on the filters analyzed by the labs cannot 
be known. The large negative bias in lab results compared to the target 
filter load implies that there was significant sample loss. In 
addition, the quality control employed by RJ Lee to ensure that filter 
loads were accurately known consisted only of an analysis of six 
separately prepared samples to evaluate the recovery from the 0.8 [mu]m 
PVC filter and two sets of filters to evaluate recovery and test for 
shipping loss (Document ID 3461, Slides 8, 15, 16; 3582, Tr. 2090-
2091). This is in stark contrast to the procedures used by the AIHA PAT 
program, which verifies its sample preparation by analyzing a 
statistically adequate number of samples prepared each quarter to 
ensure that sample variation does not exceed 10 percent 
(Document ID 3586, Tr. 3276-3277). RJ Lee's use of the 0.8 [mu]m PVC 
copolymer filter (Document ID 4001, Attachment 1) is also contrary to 
the NIOSH Method 7500 (Document ID 0901), which specifies use of the 5 
[mu]m PVC filter, and may have introduced bias. As stated at the 
hearing by Mary Ann Latko of the AIHA Proficiency Analytical Testing 
Programs, ``[a]ny variance from the NIOSH method should not be 
considered valid unless there's a sufficient quality control data 
provided to demonstrate the reliability of the modified method'' 
(Document ID 3586, Tr. 3278).
    OSHA finds that the AIHA PAT data are a far more credible measure 
of inter-laboratory variation in crystalline silica measurement than 
the ACC-sponsored RJ Lee study. Strict procedures are used to prepare 
and validate sample preparation in accordance with ISO requirements for 
conformity assessment and competence of testing in calibration 
laboratories (Document ID 3586, Tr. 3275) and the database includes 200 
rounds of silica testing since 2004, with 55 laboratories participating 
in each round (Document ID 3586, Tr. 3264-3265). By comparison, the RJ 
Lee study consisted of three rounds of testing among five laboratories.
    One of the goals of the RJ Lee study was to conduct a double-blind 
test so that laboratories would not know they were analyzing prepared 
samples for proficiency testing; according to Mr. Bailey, a 
laboratory's knowledge that they are participating in a performance 
study, such as is the case with the AIHA PAT program, ``can introduce 
bias into the evaluation from the very beginning'' (Document ID 3582, 
Tr. 1989; Document ID 4209, p. 147). However, OSHA doubts that such 
knowledge has a profound effect on laboratory performance. Accredited 
laboratories participating in the PAT program undergo audits to ensure 
that analytical procedures are applied consistently whether samples are 
received from the field or from the PAT program. According to testimony 
from Mr. Walsh:

    [S]ite assessors [for the AIHA accreditation program] are very 
sensitive to how PAT samples are processed in the lab. It's a 
specific area that's examined, and if the samples are processed in 
any way other than a normal sample, the laboratory is cited as a 
deficiency (Document ID 3586, Tr. 3299-3300).

    Therefore, after considering the evidence and testimony on the RJ 
Lee study and AIHA PAT Program data, OSHA concludes that the AIHA PAT 
data are the best available data on which to evaluate inter-laboratory 
variability in measuring respirable crystalline silica. The data 
evaluated by Harper et al. (2014) showed that laboratory performance 
has improved in recent years resulting in greater agreement between 
labs; mean RSD for the period 2003-2013 was 20.9 percent (Document ID 
3998, Attachment 8, Figure 1). In addition, across the range of PAT 
filter loadings, only about 5 percent of the samples resulted in lab 
RSDs above 25 percent. At lower filter loads, 75 [mu]g or less, about 
10 percent of samples resulted in RSDs above 25 percent Document ID 
3998, Attachment 8, Figure 2). OSHA concludes that these findings 
indicate general agreement between laboratories analyzing PAT samples.
    Although laboratory performance has not been broadly evaluated at 
filter loads below 40 [mu]g, particularly when interferences are 
present, OSHA's investigations show that the XRD method is capable of 
measuring crystalline silica at filter loads of 40 [mu]g or less 
without appreciable loss of precision. The analysis of recent PAT data 
by Harper et al. (2014, Document ID 3998, Attachment 8) shows that the 
increase seen in inter-laboratory variation with lower filter loads 
(e.g., about 50 and 70 [mu]g) is modest compared to the increase in 
variation seen in the past from earlier PAT data, and the summary data 
provided by AIHA (Document ID 4188) show that the average lab RSD for 
samples with low filter loads is only a few percentage points above 
average lab RSD across the full range of filter loads used in the PAT 
program since 1999. OSHA finds that the studies of recent PAT data 
demonstrate that laboratories have improved their performance in recent 
years, most likely as a result of improving quality control procedures 
such as were first proposed by Eller et al. (1999b, Document ID 1688, 
pp. 23-24). Such procedures, including procedures concerning equipment 
calibration, use of NIST standard reference material for calibration, 
and strict adherence to published analytical methods, are required by 
Appendix A of the final standards (29 CFR 1910.1053 and 29 CFR 
1926.1153). According to Dr. Rosa Key-Schwartz, NIOSH's expert in 
crystalline silica analysis, NIOSH worked closely with the AIHA 
laboratory accreditation program to implement a silica emphasis program 
for site visitors who audit accredited laboratories to ensure that 
these quality control procedures are being followed (Document ID 3579, 
Tr. 153). With such renewed emphasis being placed on

[[Page 16453]]

tighter procedures for crystalline silica analysis, OSHA finds that 
exposure monitoring results being received from laboratories are more 
reliable than was the case in years past and thus are deserving of 
greater confidence from employers and workers.
f. Conclusion
    Based on the record evidence reviewed in this section, OSHA finds 
that current methods to sample respirable dust and analyze samples for 
respirable crystalline silica by XRD and IR methods are capable of 
reliably measuring silica concentrations in the range of the final 
rule's PEL and action level. This finding is based on the following 
considerations: (1) Several sampling devices are available that conform 
to the ISO/CEN specification for particle-size selective samplers with 
a level of bias and accuracy deemed acceptable by international 
convention, and moving to the ISO/CEN convention will maintain 
continuity with past practice, (2) both the XRD and IR methods can 
measure respirable crystalline silica with acceptable precision at 
amounts that would be collected by samplers when airborne 
concentrations are at or around the PEL and action level, and (3) 
laboratory proficiency data demonstrate that there is reasonable 
agreement between laboratories analyzing comparable samples most of the 
time.
    There are several sampling devices that can collect respirable 
crystalline silica in sufficient quantity to be measured by laboratory 
analysis; some of these include the Dorr-Oliver nylon cyclone operated 
at 1.7 L/min air flow rate, the Higgins-Dewell cyclones (2.2 L/min), 
the SKC aluminum cyclone (2.5 L/min), and the GK2.69, which is a high-
flow sampler (4.2 L/min). Each of these cyclones can collect the 
minimum amount of silica necessary, at the PEL and action level, for 
laboratories to measure when operated at their respective flow rates 
for at least four hours. In addition, each of these devices (as well as 
a number of others) has been shown to conform to the ISO/CEN convention 
with an acceptable bias and accuracy for a wide range of particle-size 
distributions encountered in the workplace. OSHA used the Dorr-Oliver 
at a flow rate of 1.7 L/min to enforce the previous PELs for respirable 
crystalline silica, so specifying the use of sampling devices 
conforming to the ISO/CEN convention does not reflect a change in 
enforcement practice. The modest error that is associated with using 
respirable dust samplers is independent of where the PEL is set, and 
these samplers have been used for decades both by OSHA, to enforce the 
preceding silica PEL (and other respirable dust PELs), and by employers 
in managing silica-related risks. Therefore, OSHA finds that these 
samplers are capable of and remain suitable for collecting respirable 
dust samples for crystalline silica analysis.
    Both XRD and IR analytical methods are capable of quantifying 
crystalline silica with acceptable precision when air samples are taken 
in environments where silica concentrations are around the PEL and 
action level. OSHA's quality control samples analyzed by XRD over the 
past few years show the precision to be about 20 percent over the range 
of filter loads tested (about one-half to twice the former PEL). OSHA 
conducted studies to characterize the precision of its Method ID-142 at 
low filter loads representing the amounts that would be captured using 
the Dorr-Oliver cyclone at the action level and PEL (i.e., 20 and 40 
[mu]g, respectively), and found the precision, for quartz and 
cristobalite, at both 20 and 40 [mu]g to be comparable to the precision 
at the higher range of filter loads.
    Evaluation of data from AIHA's Proficiency Analytical Testing 
Program shows that results from participating laboratories are in 
agreement (i.e., within 25%) most of the time. Performance between 
laboratories has improved significantly in recent years, most likely 
due to adoption of many of the quality control practices specified by 
Appendix A of the final standards. Although precision declines as the 
amount of crystalline silica in samples declines, the rate of decline 
in precision with declining mass is less today than for prior years. 
OSHA expects that increasing emphasis on improved quality control 
procedures by the AIHA laboratory accreditation program (Document ID 
3579, Tr. 153), the requirement in the final rule for employers to use 
laboratories that use XRD or IR analysis (not colorimetric) and that 
are accredited and conform to the quality control procedures of 
Appendix A of the final standards, and increased market pressure for 
laboratories to provide reliable results are likely to improve 
agreement in results obtained by laboratories in the future.
    Inter-laboratory variability has not been well characterized at 
filter loads below 50 [mu]g, which is slightly more than would be 
collected by a Dorr-Oliver cyclone sampling a silica concentration at 
the PEL over a full shift. However, OSHA concludes that the studies 
conducted by SLTC show that acceptable precision can be achieved by the 
XRD method for filter loads obtained by collecting samples with the 
Dorr-Oliver and similar devices at the action level and PEL. If 
employers are concerned about the accuracy that their laboratory would 
achieve at filter loads this low, samplers with higher flow rates could 
be used to collect an amount of silica that falls within the working 
range of the OSHA method and within the range of filter loads currently 
used by the PAT program (i.e., 50 [mu]g or more). For example, either 
the aluminum cyclone or HD will collect at least 50 [micro]g or more of 
silica where concentrations are around the PEL, and the GK2.69 will 
collect a sufficient quantity of crystalline silica where 
concentrations are at least at the action level.
    Based on the information and evidence presented in this section, 
OSHA is confident that current sampling and analytical methods for 
respirable crystalline silica provide reasonable estimates of measured 
exposures. Employers should be able to rely on sampling results from 
laboratories meeting the specifications in Appendix A of the final 
standards to analyze their compliance with the PEL and action level 
under the new silica rule; employers can obtain assurances from 
laboratories or their industrial hygiene service providers that such 
requirements are met. Similarly, employees should be confident that 
those exposure results provide them with reasonable estimates of their 
exposures to respirable crystalline silica. Thus, OSHA finds that the 
sampling and analysis requirements under the final rule are 
technologically feasible.
3. Feasibility Findings for the Final Permissible Exposure Limit of 50 
[mu]g/m\3\
    In order to demonstrate the technological feasibility of the final 
PEL, OSHA must show that engineering and work practices are capable of 
reducing exposures to the PEL or below for most operations most of the 
time. Substantial information was submitted to the record on control 
measures that can reduce employee exposures to respirable crystalline 
silica, including but not limited to LEV systems, which could include 
an upgrade of the existing LEV or installation of additional LEV; 
process enclosures that isolate the employee from the exposure; dust 
suppression such as wet methods; improved housekeeping; and improved 
work practices. Substantial information was also submitted to the 
record on the use of respiratory protection; while OSHA does not, as a 
rule, consider the use of respirators when deciding whether an 
operation is technologically

[[Page 16454]]

feasible, it does, when it finds a particular operation or task cannot 
achieve the PEL without respiratory protection, require appropriate 
respirator use as a supplementary control to engineering and work 
practice controls, when those controls are not sufficient alone to meet 
the PEL.
    OSHA finds that many engineering control options are currently 
commercially available to control respirable dust (e.g., Document ID 
0199, pp. 9-10; 0943, p. 87; 1607, p. 10-19; 1720, p. IV-237; 3791, p. 
iii; 3585, p. 3073; 3585, p. 3072). These controls will reduce 
employees' exposures to respirable crystalline silica when the 
employees are performing the majority of tasks that create high 
exposures. OSHA's finding is based on numerous studies, conducted both 
in experimental settings in which the tools, materials and duration of 
the task are controlled by the investigator, and in observational field 
studies of employees performing their normal duties in the field. As 
detailed in Chapter IV of the FEA, more than 30 studies were submitted 
to the docket that report substantial reductions in exposure when using 
controls compared with uncontrolled situations. The specific reports 
that OSHA relied upon to estimate the range of reductions that can be 
achieved through the implementation of engineering controls are 
discussed in greater detail in the relevant sections of the 
technological feasibility analyses.
    Table VII-8 lists the general industry sectors included in the 
technological feasibility analysis and indicates the numbers of job 
categories in each sector for which OSHA has concluded that the final 
PEL of 50 [mu]g/m\3\ is technologically feasible (see Chapter IV of the 
FEA). As this table shows, OSHA has determined that the final rule's 
PEL is feasible for all general industry sectors for the vast majority 
of operations in these affected industry sectors (87 out of 90). For 
only three general industry job categories, OSHA has concluded that 
exposures to silica will likely exceed the final rule's PEL even when 
all feasible controls are fully implemented; therefore, supplemental 
respiratory protection will be needed in addition to those controls to 
ensure that employees are not exposed in excess of the PEL for those 
three categories. Specifically, supplemental use of respiratory 
protection may be necessary for abrasive blasting operations in the 
concrete products industry sector, cleaning cement trucks in the ready 
mix concrete industry sector, and during abrasive blasting operations 
in shipyards. In addition, in foundries, while finding that compliance 
with the standard is overall feasible for all job categories, OSHA 
recognizes that supplemental use of respiratory protection may be 
necessary for the subset of employees who infrequently perform 
refractory lining repair; for the small percentage of shakeout 
operators, knockout operators, and abrasive blasters who work on large 
castings in circumstances where substitution to non-silica granular 
media is not feasible; and for maintenance operators performing 
refractory patching where reduced silica refractory patching products 
cannot be used.

[[Page 16455]]

[GRAPHIC] [TIFF OMITTED] TR25MR16.044

    OSHA has determined that some engineering controls are already 
commercially available for the hydraulic fracturing industry, and other 
controls that have demonstrated promise are currently being developed. 
OSHA recognizes, however, that engineering controls have not been 
widely implemented at hydraulic fracturing sites, and no individual PBZ 
results associated with controls have been submitted to the record.
    The available information indicates that controls for dust 
emissions occurring from the sand mover, conveyor, and blender hopper 
have been effective in reducing exposures. KSW Environmental reported 
that a commercially-available control technology reduced exposures in 
one test with all 12 samples below the NIOSH recommended exposure limit 
(REL) of 50 [mu]g/m\3\ (Document ID 4204, p. 35, Fn. 21). KSW 
Environmental also stated that four additional customer tests resulted 
in 76 PBZ samples, all below 100 [mu]g/m\3\ (Document ID 4204, p. 35, 
Fn. 21). Another manufacturer of a similar ventilation system (J&J 
Bodies) reported that there was significantly less

[[Page 16456]]

airborne dust during the loading of proppant onto the sand mover when 
its dust control system was used. This dust control system was used at 
10 different hydraulic fracturing sites with reportedly good results 
(Document ID 1530, p. 5).
    These findings indicate that, with good control of the major dust 
emission sources at the sand mover and along the conveyor to the 
blender hopper, exposures can be reduced to at least 100 [mu]g/m\3\. 
Use of other dust controls, including controlling road dust (reducing 
dust emissions by 40 to 95 percent), applying water misting systems to 
knock down dust released from partially-enclosed conveyors and blender 
hoppers (reducing dust emissions by more than half), providing filtered 
booths for sand operators (reducing exposure to respirable dust by 
about half), reducing drop height at transfer points and hoppers, and 
establishing regulated areas, will further reduce exposures to 50 
[mu]g/m\3\ or below. Additional opportunities for exposure reduction 
include use of substitute proppant, where appropriate, and development 
and testing of dust suppression agents for proppant, such as that 
developed by ARG (Document ID 4072, Attachment 35, pp. 9-10). OSHA 
anticipates that once employers come into compliance with the preceding 
PEL, the additional controls to be used in conjunction with those 
methodologies to achieve compliance with the PEL of 50 [mu]g/m\3\ will 
be more conventional and readily available.
    Therefore, OSHA finds that the PEL of 50 [mu]g/m\3\ can be achieved 
for most operations in the hydraulic fracturing industry most of the 
time. As shown in Table IV.4.22-B of the FEA, this level has already 
been achieved for almost one-third of all sampled workers (and nearly 1 
in 5 sand fracturing workers, the highest exposed job category). OSHA 
expects that the growing availability of the controls needed to achieve 
the preceding PEL, along with further development of emerging 
technologies and better use and maintenance of existing controls, will 
reduce exposures to at or below the PEL for the remaining operations.
    The American Petroleum Institute (API), the Marcellus Shale 
Coalition (MSC), and Halliburton questioned whether the analysis of 
engineering controls presented in the PEA was sufficient to demonstrate 
the technological feasibility of reducing exposures to silica at 
hydraulic fracturing sites to levels at or below 50 [mu]g/m\3\, in part 
because the analysis did not include industry-specific studies on the 
effectiveness of dust controls but largely relied instead on research 
from other industries (Document ID 2301, Attachment 1, pp. 29, 60-61; 
2302, pp. 4-7; 2311, pp. 2-3). These stakeholders argued that OSHA 
needed to do significantly more data collection and analysis to show 
that the PEL of 50 [mu]g/m\3\ is feasible for hydraulic fracturing 
operations.
    OSHA sought additional information on current exposures and dust 
control practices. Throughout the NPRM and hearings, OSHA, as well as 
other stakeholders, requested additional information on exposures and 
engineering controls (Document ID 3589, Tr. 4068-4070, 4074-4078, 4123-
4124; 3576, Tr. 500, 534). Submissions to the record indicate that 
significant efforts are currently being made to develop more effective 
dust controls specifically designed for hydraulic fracturing (Document 
ID 1530; 1532; 1537; 1538; 1570; 4072, Attachments 34, 35, 36; 4204, p. 
35, Fn. 21). However, industry representatives provided no additional 
sampling data to evaluate the effectiveness of current efforts to 
control exposures. Thus, NIOSH and OSHA provided the only detailed air 
sampling information for this industry, and summary data were provided 
by a few rulemaking participants (Document ID 4204, Attachment 1, p. 
35, Fn. 21; 4020, Attachment 1, p. 4).
    When evaluating technological feasibility, OSHA can consider 
engineering controls that are under development. Under section 6(b)(5) 
of the OSH Act, 29 U.S.C. 655(b), OSHA is not bound to the 
technological status quo and can impose a standard where only the most 
technologically advanced companies can achieve the PEL even if it is 
only some of the operations some of the time. Lead I (United 
Steelworkers of Am., AFL-CIO-CLC v. Marshall, 647 F.2d 1189 (D.C. Cir. 
1980)); Am. Iron & Steel Inst. v. OSHA, 577 F.2d 825 (3d Cir. 1978). 
Relying on these precedents, the D.C. Circuit reaffirmed that MSHA and 
OSHA standards may be ``technology-forcing'' in Kennecott Greens Creek 
Min. Co. v. MSHA, 476 F.3d 946, 957, 960 (D.C. Cir. 2007), and that 
``the agency is `not obliged to provide detailed solutions to every 
engineering problem,' but only to `identify the major steps for 
improvement and give plausible reasons for its belief that the industry 
will be able to solve those problems in the time remaining.' '' Id. 
(finding that MSHA provided ``more than enough evidence,'' including 
``identif[ying] several types of control technologies that are 
effective at reducing . . . exposure,'' to conclude that the industry 
could comply with the two-year implementation date of a technology-
forcing standard) (citing Nat'l Petrochemical & Refiners Ass'n v. EPA, 
287 F.3d 1130, 1136 (D.C. Cir. 2002)).
    OSHA concluded that these technologies will enable the industry to 
comply within five years. OSHA has described technologies that have 
been developed and tested, and that have demonstrated that the PEL is 
obtainable. These technologies have been developed to reduce exposures 
to the preceding PEL, but some of them appear also to have the 
capability to reduce some exposures to the PEL of 50 [micro]g/m\3\. KSW 
Environmental has provided data that indicate exposures can be achieved 
at or below the PEL (Document ID 1570, p. 22; 4204, Attachment 1, p. 
35, Fn. 21; 4222, Attachment 2, p. 6), and NIOSH has presented concepts 
of ``mini-bag houses'' that can be retrofitted on existing equipment 
(Document ID 1537, p. 5; 1546, p. 10). SandBox Logistics, LLC, has 
developed a shipping container for bulk transport of sand specifically 
designed for hydraulic fracturing operations that eliminates the need 
for sand movers, a major source of exposure to silica at fracturing 
sites (Document ID 3589, Tr. 4148). OSHA views these and other advanced 
controls discussed above as on the ``horizon,'' but not currently 
widely available for operational use (Am. Fed'n of Labor & Cong. of 
Indus. Organizations v. Brennan, 530 F.2d 109, 121 (3d Cir. 1975)). 
Once they are deployed, as explained fully in Chapter IV of the FEA, 
more conventional adjustments and additional controls can be used with 
them to lower exposures to the new PEL or below.
    Evidence in the record shows widespread recognition of silica 
exposure hazards on hydraulic fracturing sites and industry's efforts 
to address them primarily through the efforts of the National Service, 
Transmission, Exploration & Production Safety (STEPS) network's 
Respirable Silica Focus Group. The STEPS network initiated action to 
address exposure to silica at hydraulic fracturing sites in 2010, when 
NIOSH first conducted air sampling and then publicized the severity of 
hazardous silica exposures as part of its Field Effort to Assess 
Chemical Exposures in Gas and Oil Workers (Document ID 1541). 
Recognition of silica exposures in the industry well above the 
preceding PEL of 100 [micro]g/m\3\ prompted the development of 
engineering controls to reduce exposures to silica. While some 
companies in the hydraulic fracturing industry are able to obtain and 
implement controls to comply with the preceding PEL (e.g., Document ID 
4204,

[[Page 16457]]

Attachment 1, p. 35, Fn. 21), the technology is not currently widely 
available. Given the progress that has been made since 2010, OSHA 
concluded that these technologies will become more widely available and 
enable the industry to comply with the final PEL within five years. As 
noted by Kenny Jordan, the Executive Director of the Association of 
Energy Service Companies (AESC), his organization's participation on 
the National Occupational Research Agenda (NORA) NIOSH Oil and Gas 
Extraction Council enabled members to be ``at the forefront of building 
awareness of the silica at the well site issue, particularly among 
those working in fracking operations'' (Document ID 3589, Tr. 4059). In 
the five years since that time, the substantial progress in controlling 
silica exposures at fracking sites described above has occurred.
    In June 2012, the STEPS network, in which AESC and many other 
industry, educational and regulatory entities participate, launched a 
respirable silica focus group to spread awareness, better characterize 
on-site silica exposures, and facilitate and evaluate the development 
of engineering controls (Document ID 3589, Tr. 4059; 1537). This 
enabled several manufacturers of engineering controls, such as KSW 
Environmental (formerly Frac Sand Dust Control and Dupre) who had 
developed a working model in 2009 (Document ID 1520), to collaborate 
and share information on various engineering controls. As a 
consequence, the silica control field has grown significantly during 
this period, including the development, testing and, in some cases, 
deployment of new technologies, including those from KSW Environmental, 
J&J Truck Bodies, SandBox Logistics, and NIOSH's baghouse. For example, 
John Oren, the co-inventor of the SandBox Logistics technology, said it 
had taken his company only three years to develop the product and make 
it commercially available (Document ID 3589, Tr. 4148). OSHA concludes 
that an additional five years will be more than enough time for these 
and other firms to complete development and increase manufacturing and 
sales capacity, and, simultaneously, for hydraulic fracturing employers 
to test, adopt and adapt these emerging technologies to their 
workplaces. Indeed, in light of the progress that has already been 
made, it may be more accurate to call the standard ``market-
accelerating'' than ``technology-forcing.''
    During the rulemaking, API touted the efforts of this industry to 
develop technology to protect workers against the hazards of silica 
(Document ID 4222, Attachment 2, p. 9). OSHA agrees with API that these 
efforts have been noteworthy and that more time is warranted to allow 
for continued development, commercialization, and implementation of 
these innovative technologies. OSHA is confident that with the 
innovation displayed by this industry to date, the hydraulic fracturing 
industry can further reduce worker exposures to the PEL if sufficient 
time is provided. Therefore, OSHA is providing an extra three years 
from the effective date of the standard--for a total of five years--to 
implement engineering controls for the hydraulic fracturing industry. 
OSHA concludes that this is ample time for this highly technical and 
innovative industry to come into compliance with the final PEL. This is 
consistent with, but longer than, the time frame OSHA granted for 
implementation of engineering controls for hexavalent chromium, where 
OSHA provided four years to allow sufficient time for some industries 
to coordinate efforts with other regulatory compliance obligations as 
well as gain experience with new technology and learn more effective 
ways to control exposures (71 FR 10100, 10372, Feb. 28, 2006). Thus, 
with the extra time provided for this industry to come into compliance, 
OSHA finds that the final PEL of 50 [micro]g/m\3\ is feasible for the 
hydraulic fracturing industry.
    In the two years leading up to the effective date, the hydraulic 
fracturing industry will continue to be subject to the preceding PEL in 
29 CFR 1910.1000 (Table Z). In order to meet the preceding PEL of 100 
[micro]g/m\3\ during this interim period, such compliance will include 
adoption of the new engineering controls discussed above as they become 
widely available for field use.\25\ As a result, OSHA expects many 
exposures in hydraulic fracturing to be at or near the 50 [micro]g/m\3\ 
level ahead of the five-year compliance date due to the expected 
efficacy of this new technology. Thus, with the extra time provided for 
this industry to come into compliance, OSHA finds that the standard is 
feasible for most workers in the Hydraulic Fracturing industry most of 
the time.
---------------------------------------------------------------------------

    \25\ Compliance with Table Z requires implementing all feasible 
engineering and administrative controls to achieve the PEL before 
using protective equipment such as respirators. 29 CFR 1910.1000(e). 
OSHA acknowledges that the technologies to meet the PEL in Table Z 
are not currently widely available in the quantities needed for the 
entire industry to achieve compliance. Accordingly, as employers 
work toward implementing controls during the interim period, 
supplemental respiratory protection may be necessary to comply with 
the PEL of 100 [micro]g/m\3\. Likewise, during the additional three-
year phase-in period, OSHA anticipates that many employers may need 
to use supplemental respiratory protection to comply with the PEL of 
50 [micro]g/m\3\.
---------------------------------------------------------------------------

    OSHA has determined that a PEL of 50 [micro]g/m\3\ is 
technologically feasible for the maritime industry. Although it is not 
feasible to reduce painters' exposures to 50 [micro]g/m\3\ when 
conducting abrasive blasting operations most of the time without the 
use of respirators, evidence in the record demonstrates that it is 
feasible to reduce painters' helpers' exposure to 50 [micro]g/m\3\ most 
of the time with HEPA-filtered vacuums. As noted in Chapter IV of the 
FEA, workers in the maritime industry may also be exposed during 
foundry activities; as explained in FEA Chapter IV. Section 4.8.4--
Captive Foundries, OSHA has determined that it is feasible to reduce 
exposures during most operations in captive foundries to 50 [micro]g/
m\3\, most of the time. The record evidence indicates that shipyard 
foundries face similar issues controlling silica as other typical small 
foundries (e.g., cleaning the cast metal) and that shipyard foundries 
cast items in a range of sizes, from small items like a ship's plaque 
to large items like the bow structure for an aircraft carrier (Document 
ID 1145; 3584, Tr. 2607). OSHA did not receive comments indicating that 
foundries in shipyards would require any unique controls to reduce 
exposures, and therefore believes that exposures in shipyard foundries 
can also be reduced to 50 [micro]g/m\3\ in most operations, most of the 
time. Accordingly, OSHA has determined that 50 [micro]g/m\3\ is 
feasible for most silica-related activities performed in the maritime 
industry.
    Even if captive foundries are excluded from consideration, OSHA 
considers the standard to be feasible for shipyards with the use of 
respirators by painters doing abrasive blasting. OSHA recognizes that, 
consistent with its hierarchy of controls policy for setting methods of 
compliance, respirator use is not ordinarily taken into account when 
determining industry-wide feasibility. Neither this policy nor the 
``most operations most of the time'' formulation for technological 
feasibility is meant to place OSHA in a ``mathematical straitjacket'' 
(Indus. Union Dep't, AFL-CIO v. Am. Petroleum Inst., 448 U.S. 607, 655 
(1980) (``Benzene'') (stated with respect to the ``significant risk'' 
finding, which the Supreme Court recognized is ``based largely on 
policy considerations'' (Benzene, 448 U.S. at 655 n.62)). No court has 
been confronted with a situation where an industry has two operations 
(or any even number), of which one can achieve the PEL through

[[Page 16458]]

engineering controls and the other (or exactly half) can achieve it 
most of the time only with the use of respirators. However, the same 
court that formulated the ``most operations most of the time'' standard 
``also noted that `[i]nsufficient proof of technological feasibility 
for a few isolated operations within an industry, or even OSHA's 
concession that respirators will be necessary in a few such operations, 
will not undermine' a showing that the standard is generally feasible'' 
(Amer. Iron & Steel Inst. v. OSHA, 939 F.2d 975, 980 (D.C. Cir. 1991) 
(Lead II), (quoting United Steelworkers of Am. AFL-CIO-CLC v. Marshall, 
647 F.2d 1189, 1272 (D.C. Cir. 1980) (``Lead I'')). It further 
recognized the intended pragmatic flexibility of this standard by 
stating that ``[f]or example, if `only the most technologically 
advanced plants in an industry have been able to achieve [the 
standard]--even if only in some of their operations some of the time,' 
then the standard is considered feasible for the entire industry'' 
(Lead II, 939 F. 2d at 980 (quoting Lead I, 647 F.2d at 1264)). In this 
instance, OSHA has determined that it makes sense to treat painters 
performing abrasive blasting in shipyards as an outlier for which the 
PEL established for all other covered industries is feasible, even 
conceding that respirators will be necessary. If abrasive blasting were 
the predominant activity that occurs in shipyards, there might be 
justification to set a separate, higher PEL for shipyards. But as in 
construction (for which supplemental respirator use is also 
contemplated for abrasive blasting operations), abrasive blasting is 
one of many activities that occurs; substitution of non-silica blasting 
materials is an option in many cases; few, if any, painters spend 
entire days or weeks doing blasting operations and thus needing 
respirators for the duration; and lowering the standard from 250 
[micro]g/m\3\ to 50 [micro]g/m\3\ does not threaten the economic 
viability of the industry. Under these circumstances, OSHA concludes 
that it may find the standard feasible for shipyards rather than raise 
the PEL for this single industry because it can only achieve the 
uniform PEL with respirators or, alternatively, not be able to revise 
the previous PEL of 250 [micro]g/m\3\ at all.
    Table VII-9 lists the construction application groups included in 
the technological feasibility analysis and indicates the numbers of 
tasks in each application group. As this table shows, OSHA has 
determined that the rule's PEL is feasible for the vast majority of 
tasks (19 out of 23) in the construction industry. For those 
construction tasks listed in Table 1 of paragraph (c) of the 
construction standard, OSHA has determined that the controls listed on 
Table 1 are either commercially available from tool and equipment 
manufacturers or, in the case of jackhammers, can be fabricated from 
readily available parts. Therefore, OSHA has determined that these 
control requirements are technologically feasible and will, with few 
exceptions, achieve exposures of 50 [mu]g/m\3\ or less most of the 
time. Furthermore, Table 1 in paragraph (c) of the standard for 
construction acts as a ``safe harbor'' in the sense that full and 
proper implementation of the specified controls satisfies the 
employer's duty to achieve the PEL, and the employer is under no 
further obligation to do an exposure assessment or install additional, 
non-specified controls. Thus, OSHA finds the operations listed in Table 
1 to be technologically feasible for the vast majority of employers who 
will be following the table.
    Where available evidence indicates that exposures will remain above 
this level after implementation of dust controls (see Chapter IV of the 
FEA), Table 1 requires that respiratory protection be used. OSHA has 
determined that available engineering and work practice controls cannot 
achieve exposure levels of 50 [mu]g/m\3\ or less for only two 
activities: Handheld grinders used to remove mortar (i.e., 
tuckpointing) and dowel drilling in concrete. For a few other 
activities, OSHA concludes that respiratory protection will not 
generally be needed unless the task is performed indoors or in enclosed 
areas, or the task is performed for more than four hours in a shift. 
Table 1 requires use of respiratory protection when using handheld 
power saws indoors or outdoors more than four hours per shift; walk-
behind saws indoors; dowel drills in concrete; jackhammers or handheld 
powered chipping tools indoors or outdoors more than four hours per 
shift; handheld grinders for mortar removal; and handheld grinders for 
uses other than mortar removal when used indoors for more than four 
hours per shift.
    OSHA has also evaluated the feasibility of three application groups 
that do not appear on Table 1: Underground construction, drywall 
finishing work, and abrasive blasting. For these operations, employers 
will be subject to the paragraph (d) requirements for alternative 
exposure control methods. Due in part to the complexity of excavating 
machines, dust controls, and the ventilation systems required to 
control dust for underground operations, OSHA decided not to include 
underground construction and tunneling operations in Table 1 of 
paragraph (c) of the construction standard. Nonetheless, OSHA has 
determined that the PEL is technologically feasible in underground 
construction because exposures can be reduced to 50 [micro]g/m\3\ or 
less most of the time. Drywall finishing work was not included on Table 
1 because silica-free drywall compounds are commercially available and 
can be used to eliminate exposure to silica when finishing drywall. In 
contrast to underground construction and drywall finishing, OSHA 
decided that abrasive blasting was not suited to the Table 1 approach 
because employers have several options in the control measures they can 
implement when abrasive blasting based on their particular application. 
For example, substitution to low-silica agent, use of wet blasting and 
process enclosures are all possible control options for abrasive 
blasting operations. Therefore, OSHA does not specify a specific 
control for abrasive blasting suitable for all applications, unlike the 
entries on Table 1 for tuckpointing and dowel drilling, where LEV is 
the only option accompanied by required supplemental respirator use. 
Furthermore, OSHA has existing requirements for abrasive blasting under 
the ventilation standard for construction (29 CFR 1926.57). In certain 
situations, that standard requires abrasive blasting operators to use 
abrasive blasting respirators approved by NIOSH for protection from 
dusts produced during abrasive blasting operations (29 CFR 
1926.57(f)(5)(i) through (iii)). That standard also includes 
specifications for blast-cleaning enclosures (29 CFR 1926.57(f)(3)), 
exhaust ventilation systems (29 CFR 1926.57(f)(4)), air supply and air 
compressors (29 CFR 1926.57(f)(6)), and operational procedures (29 CFR 
1926.57(f)(7)). OSHA also has similar requirements for abrasive 
blasting under the general industry standard (29 CFR 1910.94). 
Therefore, OSHA expects that respiratory protection will be required to 
be used during blasting operations under the paragraph (d) approach 
that employers must follow when employees are doing this task.

[[Page 16459]]

[GRAPHIC] [TIFF OMITTED] TR25MR16.045

    The American Chemistry Council's (ACC's) Crystalline Silica Panel 
contended that OSHA did not demonstrate that the proposed standard 
would be technologically feasible in all affected industry sectors 
because OSHA had failed to account for day-to-day environmental 
variability in exposures (Document ID 4209, Attachment 1, p. 97). ACC 
noted that OSHA enforces PELs as never-to-be-exceeded values and that 
an employer can be cited based

[[Page 16460]]

on a single measurement even if most exposures on most days are below 
the PEL. Therefore, they stated that to be ``reasonably confident of 
complying with OSHA's proposed PEL of 50 [mu]g/m\3\, the long-term 
average exposure in most workplaces likely would have to be maintained 
at a level below 25 [mu]g/m\3\ (or even below 20 [mu]g/m\3\)'' 
(Document ID 4209, p. 97; 2307, Attachment A, pp. 23-24, 160). 
Representatives from the American Foundry Society (AFS) and the Asphalt 
Roofing Materials Association (ARMA) made similar arguments (Document 
ID 2291, p. 5; 3584, Tr. 2654-2655; 3580, Tr. 1282-1284, 1289).
    OSHA recognizes the existence of exposure variability due to 
environmental factors that can affect employee exposures, especially in 
the construction industry where work sites and weather conditions can 
change on a daily basis. OSHA has acknowledged this in past rulemakings 
where the same issue was raised (e.g., benzene, 52 FR 34534; asbestos, 
53 FR 35609; lead in construction, 58 FR 26590; formaldehyde, 57 FR 
22290; cadmium, 57 FR 42102; and chromium (VI), 71 FR 10099). However, 
not all exposure variation is due to random environmental factors; 
rather, many high exposures are the result of predictable causes that 
the employer can readily identify and address in efforts to improve 
exposure control. Several studies were submitted to the docket that 
used multivariate statistical models to identify factors associated 
with increased exposure to silica during various construction 
activities (Document ID 3608, 3803, 3956, 3998 Attachment 5h). These 
studies reported that as much as 80 percent of the variability in 
respirable quartz exposures could be attributed to various exposure 
determinants included in the models, clearly indicating that not all 
variability in exposure is uncontrollable. This was also attested to at 
the hearing by Dr. Frank Mirer:

    Exposures go up and down not by magic but by particular 
conditions, differences in work methods, differences in control 
efficiency, differences in adjacent operations (Document ID 3578, 
Tr. 971).

    OSHA concludes from the evidence in the record that the consistent 
use of engineering controls will reduce exposure variability. By 
improving or adding effective controls and work practices to reduce 
employee exposures to the PEL or below, employers will reduce exposure 
variability, and this reduction will provide employers with greater 
confidence that they are in compliance with the revised PEL. OSHA does, 
however, acknowledge that exposure controls cannot entirely eliminate 
variability. Some day-to-day variability in silica exposure 
measurements may remain, despite an employer's conscientious 
application and maintenance of all feasible engineering and work 
practice controls. Nonetheless, the legal standard for finding that a 
PEL is technologically feasible for an industry sector is whether most 
employers can implement engineering and work practice controls that 
reduce exposures to the PEL or below most of the time. As explained in 
Section XV, Summary and Explanation, in situations where exposure 
measurements made by OSHA indicate that exposures are above the PEL, 
and that result is clearly inconsistent with an employer's own exposure 
assessment, OSHA will use its enforcement discretion to determine an 
appropriate response. Moreover, for the vast majority of construction 
employers (and some general industry or maritime employers doing tasks 
that are ``indistinguishable'' from Table 1 tasks and choose to comply 
with the construction standard), full compliance with Table 1 will 
eliminate the risk that an employer will be subject to citation for 
exposures above the PEL, even when the employer has instituted all 
feasible controls that normally or typically maintain exposures below 
the PEL.
    OSHA also received a number of general comments on the feasibility 
of wet methods and LEV, as well as comments on challenges faced when 
employing these dust control strategies in specific work settings. In 
general industry, several commenters indicated for specific industries 
that there was no one control that could obtain the PEL of 50 [mu]g/
m\3\ (Document ID 2264, p. 36). CISC was also critical of several 
aspects of OSHA's feasibility analysis. CISC commented that OSHA failed 
to consider exposures from secondary or adjacent sources and that OSHA 
should factor this into its analysis (Document ID 2319, p. 30; 4217, p. 
13). Dr. Mirer also stated that many employees' silica exposures are 
due to dust released from adjacent operations, but indicated that if 
these dust releases are controlled, the exposures of workers in 
adjacent areas will be substantially reduced (Document ID 4204, p. 
104). In many industries, OSHA has shown that all sources of respirable 
crystalline silica should be controlled and that often a combination of 
controls may be needed to address potential sources of silica. 
Additionally, addressing each source of exposure also reduces exposures 
in adjacent areas, thus mitigating the concern about secondary 
exposures expressed by both industry and union stakeholders.
    Other commenters addressed the use of water on construction sites; 
several commenters asserted that it is not always possible for 
employers to use water for dust suppression. For example, in its post-
hearing submission, CISC discussed what it believed to be ``significant 
obstacles'' to using wet dust suppression technologies on construction 
sites. Such obstacles include freezing weather, which contraindicates 
water use, and a lack of running water onsite, which requires employers 
to deliver water, a practice which, according to CISC, is both ``costly 
and time consuming'' (Document ID 4217, pp. 18-19). However, many other 
participants commented that these barriers can be overcome. For 
example, Phillip Rice, of Fann Contracting, Inc., uses water trucks to 
haul water to sites and includes the cost of doing so in his bids. He 
added that ``when someone says they can't get water on their project 
there is something wrong'' (Document ID 2116, Attachment 1, p. 33). 
Representatives of the International Union of Bricklayers and Allied 
Craftworkers pointed out that water is essential for work in the 
masonry trades and without it, no mortar can be mixed to set materials 
(Document ID 3585, Tr. 3059-3060). They testified that, in their 
experience, it was rare to work on sites that did not have water or 
electricity available, but when they do, they bring in water trucks and 
gas-powered generators to run saws (Document ID 3585, Tr. 3061-3063). 
With respect to weather conditions, heated water or heated shelters can 
be used if construction work is being performed in sub-freezing 
temperatures (Document ID 3585, Tr. 3095-3096).
    These comments and testimony indicate that the vast majority of the 
barriers to wet dust suppression raised by CISC have already been 
overcome in various construction settings. However, OSHA recognizes 
that there will be limited instances where the use of wet dust 
suppression is not feasible, particularly where its use can create a 
greater hazard. For example, water cannot be used for dust control in 
work settings where hot processes are present due to the potential for 
steam explosions (Document ID 2291, p. 13; 2298, p. 3), nor can it be 
used safely where it can increase fall hazards, such as on a roof 
(Document ID 2214, p. 2). Nevertheless, OSHA finds that many employers 
currently use wet dust suppression, that there are many commercially 
available products with integrated water systems for dust suppression, 
and that these products

[[Page 16461]]

can be used in most work settings to control exposures to respirable 
crystalline silica. In the limited cases where dust suppression is not 
feasible, OSHA discusses the use of alternative controls such as local 
exhaust ventilation and the supplemental use of respiratory protection, 
as needed.
    Some commenters questioned whether OSHA had adequately considered 
the difficulties in complying with the PEL for maintenance activities. 
The National Association of Manufacturers, for example, quoted one of 
its members, who stated:

[t]here are occasional conditions where maintenance cleaning is 
performed inside conveyor enclosures where the enclosure is 
ordinarily a part of the dust control systems. This is just one 
example of where a control would have to be breached in order to 
properly maintain it as well as the operating equipment. It is 
simply not technically feasible to establish engineering controls 
for all possible maintenance activities (Document ID 2380, 
Attachment 2, p. 1).

    OSHA has addressed maintenance activities in each sector's 
technological feasibility analysis, but the standard itself 
acknowledges the difficulties of some maintenance activities. Paragraph 
(g)(1)(ii) of the standard for general industry and maritime (paragraph 
(e)(1)(ii)(B) in construction) requires respiratory protection ``where 
exposures exceed the PEL during tasks, such as certain maintenance and 
repair tasks, for which engineering and work practice controls are not 
feasible'' (see the Summary and Explanation section on Respiratory 
Protection for more information).
    CISC submitted comments suggesting that the technological 
feasibility analysis was incomplete because it did not cover every 
construction-related task for which there is the potential for exposure 
to silica dust. It listed more than 20 operations, including cement 
mixing, cutting concrete pavers, demolishing drywall or plaster walls/
ceilings, overhead drilling, demolition of concrete and masonry 
structures, and grouting floor and wall tiles, that it stated OSHA must 
examine in order to establish feasibility, in addition to the 
application groups already covered by OSHA's analysis (Document ID 
2319, pp. 19-21). CISC asserted that, because of the many types of 
silica-containing materials used in the construction industry, as well 
as the presence of naturally occurring silica in soil, additional data 
collection and analysis by OSHA should be conducted before promulgating 
a final rule (Document ID 2319, pp. 25-26; 4217, p. 3).
    As explained in the NPRM, OSHA's analysis for construction focuses 
on tasks for which the available evidence indicates that significant 
levels of respirable crystalline silica may be created, due primarily 
to the use of powered tools or large equipment that generates visible 
dust. OSHA notes that many of the examples of tasks for which CISC 
requested additional analysis are tasks involving the tools and 
equipment already covered in this feasibility analysis. For example, 
overhead drilling is addressed in section IV-5.4 Hole Drillers Using 
Handheld or Stand-Mounted Drills, and the demolition of concrete and 
masonry structures is addressed in section IV-5.3 Heavy Equipment 
Operators. In other cases, such as for concrete mixing, there are no 
sampling data in the record to indicate that the task is likely to 
result in 8-hour TWA exposures above the action level. Exposure can 
occur when cleaning dried cement, and the feasibility of control 
measures to reduce exposures when cleaning out the inside of cement 
mixers is discussed in section IV-4.17 Ready Mix Concrete. Other tasks 
listed by CISC involve working with wet or intact concrete, which is 
unlikely to result in 8-hour TWA exposures above the action level. 
Further, CISC did not submit to the record any air monitoring data to 
support its assertion that these activities result in significant 
exposures. Therefore, OSHA has not added these additional activities to 
the feasibility analysis.
4. Feasibility Findings for an Alternative Permissible Exposure Limit 
of 25 [mu]g/m\3\
    In the NPRM, OSHA invited comment on whether it should consider a 
lower PEL because it determined there was still significant risk at the 
proposed PEL of 50 [mu]g/m\3\ (78 FR 56288, September 12, 2013). OSHA 
has determined that the rule's PEL of 50 [mu]g/m\3\ is the lowest 
exposure limit that can be found to be technologically feasible based 
on the rulemaking record. Specifically, OSHA has determined that the 
information in the rulemaking record either demonstrates that the 
proposed alternative PEL of 25 [mu]g/m\3\ would not be achievable for 
most of the affected industry sectors and application groups or the 
information is insufficient to conclude that engineering and work 
practice controls can consistently reduce exposures to or below 25 
[mu]g/m\3\. Therefore, OSHA cannot find that the proposed alternative 
PEL of 25 [mu]g/m\3\ is achievable for most operations in the affected 
industries, most of the time.
    The UAW submitted comments and data to the record, maintaining that 
a PEL of 25 [mu]g/m\3\ is technologically feasible. As evidence, it 
submitted exposure data from a dental equipment manufacturing plant and 
two foundries (Document ID 2282, Attachment 3, pp. 7-8; 4031, pp. 3-8) 
showing that exposures to silica in these establishments were 
consistently below 25 [mu]g/m\3\ TWA. However, OSHA cannot conclude 
that exposure data from three facilities is representative of the wide 
array of facilities affected by the rule or sufficient to constitute 
substantial record evidence that a PEL of 25 [mu]g/m\3\ is 
technologically feasible in most operations most of the time.
    Although available exposure data indicate that exposures below 25 
[mu]g/m\3\ have already been achieved for most employees in some 
general industry sectors and construction application groups (e.g., 
dental laboratories, jewelry, and paint and coatings in general 
industry, and drywall finishers and heavy equipment operators 
performing excavation in construction), the relatively low exposures 
can be attributed to the effective control of the relatively small 
amounts of dust containing silica generated by employees in these 
industries and application groups. Further extrapolation to other 
sectors or groups with higher baseline exposures or more challenging 
control situations is not warranted, however.
    For most of the industries and application groups included in this 
analysis, a review of the sampling data indicates that an alternative 
PEL of 25 [mu]g/m\3\ cannot be achieved with engineering and work 
practice controls. OSHA finds that engineering and work practice 
controls will not be able to consistently reduce and maintain exposures 
to an alternative PEL of 25 [mu]g/m\3\ in the sectors that use large 
quantities of silica containing material, including foundries (ferrous, 
nonferrous, and non-sandcasting), concrete products, and hydraulic 
fracturing, or have high energy operations, such as jackhammering and 
crushing machines.
    For instance, in the ferrous foundry industry, the baseline median 
exposure in the profiles exceeds 50 [mu]g/m\3\ for 6 of the 12 job 
categories analyzed: Sand system operators, shakeout operators, 
abrasive blasting operator, cleaning/finishing operators, maintenance 
operators, and housekeeping employees. OSHA concluded that engineering 
and work practice controls can reduce TWA exposures to 50 [mu]g/m\3\ or 
less for most of these operations most of the time. However, because 
large amounts of silica-containing sand is transported, used, and 
recycled to create castings, OSHA cannot conclude that available 
controls can reduce exposures to or below 25 [mu]g/m\3\ in any step of 
the

[[Page 16462]]

production process. Additionally, high energy operations in foundries 
can create concentrations of respirable silica above 25 [mu]g/m\3\. For 
example, the shakeout process is a high energy operation using 
equipment that separates castings from mold materials by mechanically 
vibrating or tumbling the casting. The dust generated from this process 
causes elevated silica exposures for shakeout operators and often 
contributes to exposures for other employees in a foundry. The 
effectiveness of dust controls on shakeout operations was demonstrated 
at three foundries that implemented various dust controls in the 
shakeout area (e.g., shakeout enclosure added, ventilation system 
improved, conveyors enclosed and ventilated); full-shift samples taken 
by or for OSHA measured exposures for shakeout operators ranging from 
less than or equal to 13 [mu]g/m\3\ to 41 [mu]g/m\3\ (Document ID 1365, 
pp. 2-51; 1407, p. 20; 0511, p. 2). These readings were obtained in 
foundries that had made a systematic effort to identify and abate all 
sources of dust emission with the establishment of an abatement team 
consisting of an engineer, maintenance and production supervisors, and 
employees. TWA exposures for the shakeout operators were reduced to 
less than 50 [mu]g/m\3\, but two of the four measurements in this well-
controlled facility exceeded 25 [mu]g/m\3\ (see Chapter IV 4.8.1 of the 
FEA). Other industry sectors that use substantial quantities of 
crystalline silica as a raw material include refractories, glass 
products, mineral processing, structural clay and cement products. OSHA 
finds that the available evidence on exposures at facilities in these 
industries in which controls have been implemented indicates most 
exposures are typically between 25 [mu]g/m\3\ and 50 [mu]g/m\3\.
    For other general industry sectors, OSHA has insufficient data to 
demonstrate that engineering and work practice controls will reduce 
exposures to or below 25 [mu]g/m\3\ most of the time (see Chapter IV of 
the FEA). For example, it is not evident that exposures can be reduced 
to 25 [mu]g/m\3\ for four out of five jobs analyzed in the pottery 
sector, for two out of three job categories in the structural clay 
sector, and for two jobs in the porcelain enameling sector.
    OSHA has also determined that application groups in construction 
that use large quantities of silica containing material or involve high 
energy operations will not be able to consistently achieve 25 [mu]g/
m\3\ (e.g. tuck pointing/grinding and rock and concrete drilling). 
These operations cause employees to have elevated exposures even when 
available engineering and work practice controls are used. Examples 
include using jackhammers during demolition of concrete and masonry 
structures, grinding concrete surfaces, using walk-behind milling 
machines, operating rock and concrete crushers, and using portable saws 
to cut concrete block. For instance, jackhammering is a high energy 
operation and OSHA finds that when employees perform this operation for 
four hours or less in a shift, most employees using jackhammers 
outdoors experience levels at or below 50 [mu]g/m\3\ TWA but not 
reliably at or below 25 [mu]g/m\3\. The use of portable cut-off saws (a 
type of handheld power saw) is also a high energy operation that can 
lead to exposures over 25 [mu]g/m\3\. Due to energy applied to the 
material being cut from the rapid rotation of the circular blade, the 
dust generated can be difficult to control; available data indicate 
that exposures will often exceed 25 [mu]g/m\3\ TWA, even when the 
portable cut-off saw is used with water for dust suppression. Evidence 
in the record indicates that, for most of the other construction 
operations examined, use of feasible engineering and work practice 
controls will still result in frequent exposures above 25 [mu]g/m\3\. 
For other tasks in construction application groups, OSHA has 
insufficient data to demonstrate that engineering and work practice 
controls will reduce exposures to or below 25 [mu]g/m\3\ most of the 
time (see Chapter IV of the FEA).
    Therefore, OSHA concludes that 50 [mu]g/m\3\ as an 8-hour TWA is 
the lowest feasible exposure limit that the record demonstrates can be 
applied to most general industry, maritime, and construction operations 
without the excessive use of respirators. OSHA also concludes that it 
would hugely complicate both compliance and enforcement of the rule if 
it were to set a PEL of 25 [mu]g/m\3\ for a minority of industries or 
operations where it would be technologically feasible and a PEL of 50 
[mu]g/m\3\ for the remaining industries and operations where 
technological feasibility at the lower PEL is either demonstrably 
unattainable, doubtful or unknown. OSHA is not under a legal obligation 
to issue different PELs for different industries or application groups, 
but may exercise discretion to issue a uniform PEL if it determines 
that the PEL is technologically feasible for all affected industries 
(if not for all affected operations) and that a uniform PEL would 
constitute better public policy (see Section II, Pertinent Legal 
Authority (discussing the chromium (VI) decision)). In declining to 
lower the PEL to 25 [mu]g/m\3\ for any segment of the affected 
industries, OSHA has made that determination here.

E. Costs of Compliance

Overview
    This section assesses the costs to establishments in all affected 
industry sectors of reducing worker exposures to silica to an 8-hour 
time-weighted average (TWA) permissible exposure limit (PEL) of 50 
[mu]g/m\3\--or, alternatively, for employers in construction to meet 
the Table 1 requirements--and of complying with the standard's 
ancillary requirements. This cost assessment is based on OSHA's 
technological feasibility analysis presented in Chapter IV of the FEA; 
analyses of the costs of the standard conducted by OSHA's contractor, 
Eastern Research Group; testimony during the hearings; and the comments 
submitted to the docket as part of the rulemaking process.
    OSHA estimates that the standard will have a total cost of $1,029.8 
million per year in 2012 dollars. Of that total, $370.8 million will be 
borne by the general industry and maritime sectors, and $659.0 million 
will be borne by the construction sector. Costs originally estimated 
for earlier years in the PEA were adjusted to 2012 dollars using the 
appropriate price indices. In general, all employee and supervisor 
wages (loaded) were from the 2012 BLS OES (Document ID 1560); medical 
costs were inflated to 2012 dollars using the medical services 
component of the Consumer Price Index; and, unless otherwise specified, 
all other costs were inflated using the GDP Implicit Price Deflator 
(Document ID 1666).
    All costs were annualized using a discount rate of 3 percent, 
which--along with 7 percent \26\--is one of the discount rates 
recommended by OMB. Annualization periods for expenditures on equipment 
are based on equipment life, while there is a 10-year annualization 
period for one-time costs. Note that the benefits of the standard, 
discussed in Section VII.G of this preamble and in Chapter VII of the 
FEA, were annualized over a 60-year period to reflect the time needed 
for benefits to reach steady-state values. Therefore, the time horizon 
of OSHA's complete analysis of this rule is 60 years. Employment and 
production in affected

[[Page 16463]]

industries are being held constant over this time horizon for purposes 
of the analysis. All non-annual costs are estimated to repeat every ten 
years over the 60-year time horizon, including one-time costs that 
recur because of changes in operations over time or because of new 
entrants that must comply with the standard.\27\ Table VII-10 shows, by 
affected industry in the sectors of general industry and maritime, 
annualized compliance costs for all establishments, all small entities 
(as defined by the Small Business Act and the Small Business 
Administration's (SBA's) implementing regulations; see 15 U.S.C. 632 
and 13 CFR 121.201), and for all very small entities (those with fewer 
than 20 employees). Table VII-11 similarly shows, by affected industry 
in construction, annualized compliance costs for all entities, all 
small entities, and all very small entities. Note that the totals in 
these tables and all other tables in this chapter, as well as totals 
summarized in the text, may not precisely sum from underlying elements 
due to rounding.
---------------------------------------------------------------------------

    \26\ Appendix V-D of the FEA presents costs by NAICS industry 
and establishment size category using, as alternatives, both a 7 
percent discount rate and a 0 percent discount rate. In the 
sensitivity analysis presented in Chapter VII of the FEA, OSHA 
compares the estimated cost of the rule using the 3 percent discount 
rate to the estimated cost using these alternative discount rates.
    \27\ To the extent one-time costs do not recur, OSHA's cost 
estimates, when expressed as an annualization over a 10-year period, 
will overstate the cost of the standard.
---------------------------------------------------------------------------

    OSHA's exposure profile, presented in Chapter III of the FEA, 
represents the Agency's best estimate of current exposures (i.e., 
baseline exposures). Except for compliance with Table 1 in 
construction, OSHA did not attempt to determine the extent to which 
current exposures in compliance with the new silica PEL are the result 
of baseline engineering controls or the result of other circumstances 
leading to low exposures. This information is not needed to estimate 
the costs of (additional) engineering controls needed to comply with 
the new PEL, but it is relevant to estimate the costs of complying with 
Table 1 in construction.
    For both construction and general industry/maritime, the estimated 
costs for the silica rule represent the additional costs necessary for 
employers to achieve full compliance with the new standard, assuming 
that all firms are compliant with the previous standard. Thus, the 
estimated costs do not include any costs necessary to achieve 
compliance with previous silica requirements, to the extent that some 
employers may not be fully complying with previously-applicable 
regulatory requirements. OSHA almost never assigns costs for reaching 
compliance with an already existing standard to a new standard 
addressing the same health issues. Nor are any costs associated with 
previously-achieved compliance with the new requirements included.
    Because of the severe health hazards involved, as well as current 
OSHA regulation, the Agency expects that the estimated 11,640 abrasive 
blasters in the construction sector and the estimated 3,038 abrasive 
blasters in the maritime sector are currently wearing respirators as 
required by OSHA's abrasive blasting provisions (29 CFR 1915.154 
(referencing 29 CFR 1910.134)). Furthermore, an estimated 264,761 
workers, including abrasive blasters, will need to use respirators at 
least once during a year to achieve compliance with the new silica rule 
in construction, and, based on the NIOSH/BLS respirator use survey 
(NIOSH/BLS, 2003, Document ID 1492), an estimated 56 percent of 
construction employees whose exposures are high enough that they will 
need respirators under the new rule currently use such respirators. 
OSHA therefore estimates that 56 percent of affected construction 
employees already use respirators in compliance with the respirator 
requirements of the final silica rule.
    Other than respiratory protection, OSHA did not assume baseline 
compliance with any other ancillary provision, even though some 
employers have reported that they currently monitor silica exposure, 
provide silica training, and conduct medical surveillance.
    The remainder of this chapter is organized as follows. First, unit 
and total costs by provision are presented for general industry and 
maritime and for construction. Following that, the chapter concludes 
with a summary of the estimated costs of the rule for all affected 
industries.
BILLING CODE 4510-26-P

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BILLING CODE 4510-26-C
1. Engineering Controls
a. General Industry and Maritime
    The engineering control section in Chapter V of the FEA covers 
OSHA's estimates of engineering control costs for general industry and 
maritime sectors. Oil and natural gas fracturing operations are 
addressed separately because OSHA used a different methodology to 
estimate engineering control costs for this application group. This 
section will address OSHA's overall methodology, the methodology for 
each category of costs (such as ventilation, housekeeping, conveyors), 
issues specific to small entities, and issues specific to the hydraulic 
fracturing industry. Within each of these discussions, this section 
summarizes the methodology used in the PEA to estimate engineering 
control costs, summarizes and responds to the comments on the PEA, and 
summarizes the changes made to the methodology used in the PEA for the 
FEA. Finally, the chapter presents OSHA's final estimates of 
engineering control costs.
Introduction
    The PEA's technological feasibility analysis identified the types 
of engineering controls that affected industries or sectors would need 
in order to control worker exposures to at

[[Page 16469]]

or below the proposed PEL of 50 [mu]g/m\3\. Through its contractor, 
Eastern Research Group (ERG), OSHA generated cost estimates for those 
controls using product and technical literature, equipment vendors, 
industrial engineers, industrial hygienists, and other sources, as 
relevant to each item. Wherever possible, objective cost estimates from 
recognized technical sources were used. Specific sources for each 
estimate were presented with the cost estimates.
    Table V-4 of the PEA provided a list of possible controls on an 
industry-by-industry basis and included details on control 
specifications and costs. The basic information for the types of 
controls needed was taken from the PEA's technological feasibility 
analysis. The following discussion explains how OSHA developed and used 
these estimates to prepare the aggregate costs of engineering controls 
presented in the PEA.
    In developing engineering control cost estimates for the PEA, OSHA 
made a variety of estimates about the size or scope of the engineering 
or work practice changes necessary to reduce silica exposures in 
accordance with the proposed rule. In some cases, OSHA estimated that 
employers would need to install all new engineering controls. In other 
cases, though, employers were expected to only need to add additional 
ventilation capacity or improve maintenance for existing equipment. In 
these cases, the costs were based on judgments of the amount of 
incremental change (either additional capacity or additional 
maintenance work) required per year. These estimates of the size or 
scope of the necessary engineering or work practice changes reflected 
representative conditions for the affected workers based on technical 
literature (including National Institute for Occupational Safety and 
Health (NIOSH) Health Hazard Evaluations), judgments of knowledgeable 
consultants and industry observers, and site visits. A detailed list of 
the specific costing assumptions and information sources for each 
control, grouped by job category or industry sector, was shown in PEA 
Appendix V-A, Table V-A-1.
    In order to estimate costs in a consistent manner, OSHA, in the 
PEA, estimated all costs on an annualized basis. For capital costs, 
OSHA calculated the annualized capital cost, using a three percent 
discount rate over the expected lifetime of the capital item. The 
capital costs for long-lasting capital items (such as ventilation 
system improvements) were annualized over ten years. OSHA estimated 
that, in the general industry and maritime sectors, any capital 
expenditure would also entail maintenance costs equal to ten percent of 
the value of the capital investment annually.
General Methodology
General Methodology: Per-Worker Basis and Treatment of Overexposures 
for Cost Calculations
PEA Estimates
    OSHA, in the PEA, estimated control costs on a per-worker basis. 
Costs were related directly to the estimates of the number of workers 
needing controls (i.e., workers exposed over 50 [mu]g/m\3\). OSHA 
divided engineering control costs into two categories: (1) Those only 
needed by establishments with employees exposed to levels of silica 
that exceeded the preceding general industry PEL of 100 [mu]g/m\3\; and 
(2) those applicable to all establishments where workers were exposed 
to levels of silica above the proposed PEL (whether just above 50 
[mu]g/m\3\ or also above 100 [mu]g/m\3\). It should be noted that the 
maritime sector has been subject to a different preceding PEL of 250 
[mu]g/m\3\. The PEA estimates were presented in the PEA cost analysis 
tables. The overwhelming majority of the costs (90 percent of all 
engineering control costs and 85 percent of costs associated with 
meeting the preceding PEL of 100 [mu]g/m\3\) were associated with the 
second category (controls applicable to all establishments with 
exposures above the proposed or preceding PEL). Because OSHA is not 
accounting for the costs of controls necessary to reach the preceding 
PEL, the PEA focused on controls that may be needed to meet the new 
PEL. OSHA derived per-worker costs by examining the controls needed for 
each job category in each industry and dividing the cost of that 
control by the number of workers whose exposures would be reduced by 
that control. OSHA then multiplied the estimated per-worker control 
cost by the number of workers exposed between the proposed (new) PEL of 
50 [mu]g/m\3\ and the preceding PEL of 100 [mu]g/m\3\. The numbers of 
workers in this category were based on the exposure profiles for at-
risk occupations developed in the technological feasibility analysis in 
Chapter IV of the PEA and the estimates of the number of workers 
employed in these occupations were developed in the industry profile in 
Chapter III of the PEA. The exposure profile information was determined 
to be the best available data for estimating the need for incremental 
controls on a per-worker basis.
    In general, in the PEA, OSHA inferred the extent to which exposure 
controls were already in place from the distribution of overexposures 
among the affected workers. Thus, if most exposures in a facility were 
above the preceding PEL, OSHA broadly interpreted this as a sign of 
limited or no controls, and if most exposures were below the proposed 
(new) PEL of 50 [mu]g/m\3\, this would be indicative of having adequate 
controls in place. OSHA calculated the costs of controls per exposed 
worker in each job category and assigned this cost to the total number 
of employees exposed between the proposed (new) PEL and the preceding 
PEL. For example, if a control cost $1,000 per year and covered 4 
employees, the cost per employee would be $250 per year. If 100 
employees in the job category were exposed between the preceding and 
proposed (new) PEL, then the total costs would be $250 times 100 
employees or $25,000. No costs were estimated for employees currently 
exposed above the preceding PEL or below the proposed (new) PEL.
    OSHA determined that multiple controls would be needed for almost 
all jobs in general industry in order reduce exposures from baseline 
conditions to meeting the proposed (new) PEL of 50 [mu]g/m\3\. Some of 
these controls cover a group of workers, while others might be 
individualized (such as daily housekeeping by each individual worker).
Comments on the Per-Worker Basis and Proportionality of Costs
    URS, speaking for the American Chemistry Council (ACC), argued that 
OSHA's approach underestimated the costs of controls because it based 
costs on controls per worker instead of controls per facility (Document 
ID 2307, Attachment 8, p. 4). Since OSHA did not provide a distribution 
of exposures by facility or provide facility-specific information, URS 
used data in the record to create its own models to account for 
facility size. URS described its approach as follows:

    URS created three statistical binomial distributions of 
overexposed workers, one for each of the three facility sizes, using 
OSHA's estimate of the percentage of over-exposed workers for that 
job. The result was a binomial distribution curve indicating the 
percentage of overexposed workers for each job category for each 
size-specific ``model facility.''
    For each binomial distribution, the peak of the distribution 
curve centers on the average number of overexposed workers per 
facility for that job description according to OSHA's estimate 
(Document ID 2307, Attachment 8, p. 7).

    In taking this approach, URS erroneously assumed that the

[[Page 16470]]

distribution of overexposed workers per facility was random, as 
evidenced by its use of a binomial distribution to approximate 
overexposures per facility within each of three facility sizes 
(Document ID 2307, Attachment 8, p. 7). Examination of the spreadsheet 
URS provided shows that this approach approximately doubles the number 
of controls needed and, and for this reason, doubles the total cost of 
engineering controls (Document ID 2307, Attachment 26, Table 2A, URS 
Summary Worksheet).
    OSHA disagrees with URS's implicit conclusion that overexposures 
are random across facilities. It is not reasonable to assume that 
controls have no relation to exposure level as this approach assumes. 
As will be discussed later in the context of OSHA's treatment of the 
preceding PEL, the data underlying the exposure profile show that 
establishments with low exposures are much more likely to have controls 
in place than those with very high exposures.
    URS then assumed that if one worker in a job category is 
overexposed, then all controls listed by OSHA will be needed (Document 
ID 2307, Attachment 25, Engineering Costs). URS did not dispute that 
multiple controls would be needed for almost all jobs in general 
industry in order reduce exposures from baseline conditions to meeting 
the proposed (new) PEL of 50 [mu]g/m\3\. The existence of multiple 
controls weakens the theory suggested by URS--that all controls are 
needed if even one worker is exposed at levels above the PEL--because 
as explained above, some controls are individualized while some protect 
groups of workers.
    The best possible approach to what engineering controls are needed 
might differ based on whether: (1) There are no controls for a job 
category in place at all and most workers are overexposed by a large 
margin; or (2) only some workers in a job category are overexposed by a 
small margin (i.e., a set of controls is already in place).
    In the first case, the most common approach would be to apply a 
relatively full set of controls, as explained in OSHA's technological 
feasibility analysis. This might start with enclosures and local 
exhaust ventilation (LEV), but, if exposures are high and the 
establishment is very dusty, it might also include initial cleaning or 
the introduction of ongoing routine housekeeping. In these situations, 
in which most employees are overexposed, OSHA estimated that the full 
set of controls listed in the technological feasibility analysis would 
be applied and, in these cases, there would be little difference in the 
results obtained using OSHA's approach and the results obtained using 
the approach suggested by URS.
    However, the approach to controlling silica exposures that OSHA 
believes to be typical when establishments are faced with the second 
situation would be quite different, and therefore different from what 
URS expected. Commenters from both labor (Document ID 4204, p. 40) and 
industry (Document ID 1992, p. 6) pointed out that when there are 
controls in place or only some workers are overexposed, the first step 
is to examine work practices. The AFL-CIO noted that exposures can be 
controlled through work practices, repositioning ventilation systems, 
and controlling fugitive emissions (carryover from adjacent silica 
emitting processes) (Document ID 4204, p. 40). Implementing these types 
of changes can be inexpensive. The principal cost of improving work 
practices may only be training or retraining workers in appropriate 
work practices. OSHA's proportional cost approach in the PEA may 
therefore overestimate costs for situations in which overexposures can 
be corrected with work practice changes because the Agency will have 
included costs for engineering controls when, in fact, none will be 
needed. The URS approach will always include the costs of all controls 
for a job category in any facility where anyone in a job category is 
overexposed, and will thus yield even higher estimates.
    As described in Chapter IV, Technological Feasibility, of the FEA, 
and summarized below, in situations in which there are LEV systems in 
place but the PEL is still not being met, employers would typically try 
many things short of removing the entire system and replacing it with a 
system with greater air flow velocities (and thus greater capacity and 
cost). The incremental solutions to controlling silica exposures 
include minor design modification of existing controls, better repair 
and maintenance of existing controls, adding additional LEV capacity to 
existing systems, improving housekeeping, modifying tools or machinery 
causing high levels of emissions, and reducing cross contamination.
    Some worksites might require a slightly different and readily 
modified design. For example, an OSHA special emphasis program 
inspection of a facility in the Concrete Products industry discovered 
that installing a more powerful fan motor, installing a new filter bag 
for the bag-filling machine LEV, and moving hoods closer to the packing 
operator's position reduced respirable dust exposure by 92 percent, to 
11 [mu]g/m\3\ (Document ID 0126, pp. 7-8). In an assessment of the 
Asphalt Roofing industry, NIOSH recommended repair and servicing of 
existing process enclosures and ventilation systems to eliminate leaks 
and poor hood capture but did not indicate that entirely new systems 
would need to be installed (Document ID 0889, pp. 12-13; 0891, pp. 3 
and 11; 0890, p.14; 0893, p. 12).
    In other cases, better equipment repair and maintenance procedures 
can be the key to meeting the PEL when there are already controls in 
place. For example, as described in Chapter IV of the FEA, in the 
Concrete Products industry, OSHA obtained a sample of 116 [mu]g/m\3\ 
for a material handler who operated a forklift to transport product 
between stations. The inspector noted that there were leaks in the silo 
bin chute and that some controls were not fully utilized. The report 
indicated that dust generated by various other processes in the 
facility was a contributing factor to the forklift operator's high 
level of exposure. In this case, the first course of action for the 
employer would be to correct the deficiencies in the existing systems. 
Similarly, at a site visit in the Paint and Coating industry, ERG 
monitored mixer operators' exposures and obtained results below the 
limit of detection while workers emptied 50-pound bags of powder into 
hoppers when dust control systems were working properly. These values 
are 95 percent lower than the 263 [mu]g/m\3\ obtained during another 
shift, at the same plant, when the dust control systems malfunctioned 
(Document ID 0199, p. 9).
    In other cases, as pointed out by a foundry commenter, adding LEV 
capacity to existing systems for silica emissions not yet subject to 
any LEV control can be a good strategy for lowering exposures (Document 
ID 1992, p. 6). In one foundry, NIOSH investigators recommended 
installation of LEV over the coater and press areas, enclosure of the 
coating process, and/or repair and servicing of existing process 
enclosures and ventilation systems to eliminate leaks and poor hood 
capture (Document ID 0889, pp. 12-13; 0891, pp. 3 and 11; 0890, p. 14; 
0893, p. 12).
    Various combinations of improved housekeeping, initial cleaning, 
and switching to High-Efficiency Particulate Air (HEPA) vacuums can 
also help employers meet the PEL. In the Structural Clay industry, 
professional cleaning in a brick manufacturing facility removed 
``several inches'' of dust from floors, structural surfaces and 
equipment (Document ID 1365, pp. 3-19-3-20; 0571). These changes alone 
led

[[Page 16471]]

to a dramatic decrease in exposures, by as much as 90 percent, to below 
50 [mu]g/m\3\, for materials handlers. Similar results were observed 
for grinding operators (Document ID 0571). In one NIOSH evaluation, 
operators in a grinding area where good housekeeping practices were 
being implemented had substantially lower exposures than operators in a 
grinding room where the housekeeping practices were poor. The grinding 
room referred to as the ``C plant'' had 2 to 3 inches of settled dust 
on the floor and had an exposure result of 144 [mu]g/m\3\. Grinding 
operators at the grinding room referred to as the ``B plant,'' where 
dust had been cleaned up, had substantially lower exposures (24 [mu]g/
m\3\) (Document ID 0235, pp. 6-7).
    Good housekeeping also increases the useful life of equipment. As 
discussed in Chapter IV of the FEA, dust clogs machines and reduces 
their useful life. As an example, regulating cotton dust was 
acknowledged to increase productivity by reducing down time. It also 
increased the useful life of looms (Document ID 2256, Attachment 4, p. 
11). The Agency predicts that this is likely to be the case with silica 
controls as well. Dust being properly captured at the source can also 
result in cost savings in housekeeping activities because less dust 
needs to be cleaned up when it is captured at the source and not 
allowed to spread (Document ID 2256, Attachment 4, p. 11).
    In specific situations, there are a variety of other controls that 
may be useful. As discussed in the Technological Feasibility chapter of 
the FEA, Simcox et al. (1999) (Document ID 1146) found that Fabricators 
in the Cut Stone industry had a mean exposure of 490 [mu]g/m\3\, which 
was reduced 88 percent to 60 [mu]g/m\3\ when dry grinding tools used on 
granite were replaced or modified to be water-fed. Similar reductions 
were found at other facilities when wet grinding, polishing, and 
cutting methods were adopted (Document ID 1365, p. 11-20; 1146, p. 
579). In the technological feasibility chapter, OSHA examined the work 
practices of cut stone splitters and chippers and found that a 
combination of wetting the floor at appropriate times, modifying 
ventilation directly from the top of the saws, and retrofitting 
splitting stations with LEV reduced exposures from a mean of 117 [mu]g/
m\3\ to a mean of 18 [mu]g/m\3\, an 85 percent reduction (Document ID 
1365, p. 11-22; 0180).
    Finally, in situations where there is cross contamination, 
employers may achieve the PEL for some workers without implementing any 
controls specific to that job category. As pointed out by the AFL-CIO, 
when this occurs, OSHA's costs may be overestimated (Document ID 4204, 
Attachment 1, p. 105).
    These examples show that in many situations, where there are 
already controls in place, or where exposures are only slightly above 
the PEL, the PEL can be met by a variety of mechanisms short of 
installing an entirely new set of controls. Since the record shows 
that, frequently, exposures can be controlled without installing new 
engineering controls, OSHA's approach of estimating costs based on the 
proportion of the workers exposed above the PEL is much more likely to 
be accurate than estimates based on URS's suggestion that all controls 
are needed whenever one worker is exposed above the PEL.
    The URS facility-based approach would require taking the costs of 
newly installing a full set of controls even if only one worker is 
exposed above the PEL. This approach assumes that (1) the existing 
exposure levels in a given facility have been achieved without the use 
of any controls; and (2) existing controls cannot be improved upon for 
less than the cost of installing an entirely new system of controls. 
These assumptions are unsupported by the URS comments and the nature of 
exposure control, as discussed above.
    OSHA, therefore, rejects URS's approach and is maintaining its per-
worker basis for calculating costs for the FEA. Based on the evidence 
presented in this section, the Agency concludes that OSHA's 
proportional approach of assigning control costs to each worker based 
on the cost per worker of a complete set of controls is a better 
approach to commonly encountered exposure situations than to assume 
that any reading above the PEL triggers the need for a complete set of 
controls.
    The AFL-CIO argued that OSHA's proportional approach resulted in an 
over-estimation of costs because it involved adding costs for the 
exposed occupation wherever there was an overexposure, even when the 
overexposure was primarily or solely the result of cross contamination. 
The AFL-CIO recommended that OSHA ``identify operations which are 
unlikely to [generate] silica emissions, or background and bystander 
exposure measurements, and subtract those measured exposure levels from 
those operations which do emit silica'' (Document ID 4204, Attachment 
1, pp. 31-32). OSHA has routinely included the elimination of cross 
contamination as a component of the controls needed for some job 
categories. As discussed in Chapter IV of the FEA, OSHA also believes 
that other controls will still be needed for many job categories in 
which cross contamination is common and as long as these additional 
controls are needed, overall costs will not decline as a result of 
controlling cross contamination. However, OSHA agrees that there may be 
situations in which correcting cross contamination alone would be 
sufficient. In this case, the commenter is right that OSHA may 
sometimes overestimate costs.
General Methodological Issues--Comments on Costs Associated With 
Exposures Over the Preceding PEL
    Many commenters argued that OSHA should have attributed the costs 
of reaching the preceding PEL of 100 [mu]g/m\3\ to this standard 
(Document ID 2307, Attachment 8b, p. 16; 2195, p. 33; 1819, p. 2; 2375, 
Attachment 2, p. 65; 2307, Attachment 1, p. 2; 2379, Attachment 2, p. 
9). For example, Stuart Sessions of Environomics, commenting on behalf 
of the ACC, stated that of the workers currently exposed over 50 [mu]g/
m\3\, two-thirds are exposed over 100 [mu]g/m\3\, and that OSHA erred 
in excluding the costs of reducing those exposures to 100 [mu]g/m\3\ 
(Document ID 2307, Attachment C, pp. 2-3).
    OSHA's preliminary initial regulatory flexibility analysis (PIRFA) 
for the 2003 Small Business Advocacy Review (SBAR) panel included 
benefits and costs associated with future compliance with existing 
silica requirements on the basis that the rule would help improve 
compliance with the existing silica rules (OSHA, 2003a and 2003b) 
(Document ID 1685 and 0938, respectively). Upon further consideration, 
OSHA determined that a more fair and accurate measure of the benefits 
and costs of the proposed rule was to begin the analysis with a 
baseline of full compliance with existing requirements; OSHA has 
retained this approach for the final rule. The Agency offers three 
reasons in support of this approach. First, the obligation to comply 
with the preceding silica PEL is independent of OSHA's actions in this 
rulemaking. The benefits and costs associated with achieving compliance 
with the preceding silica rules are a function of those rules and do 
not affect the choice of PEL. The question before the Agency was 
whether to adopt new rules, and its analysis focused on the benefits 
and costs of those new rules. Second, the Agency's longstanding policy 
is to assume 100 percent compliance for purposes of estimating the 
costs and benefits of new rules, and to assume less than full 
compliance with the existing OSHA rules would be inconsistent with that 
policy. Finally, assuming full compliance with the existing rules is in 
keeping with standard OSHA practice in

[[Page 16472]]

measuring the incremental effects of a new rule against pre-existing 
legal obligations. Reliance on costs that assume full compliance with 
both the preceding and proposed (new) OSHA rules makes it easier to 
compare the two regulatory schemes.
    Some commenters also disagreed with the way OSHA attributed costs 
to employers whose workers were being exposed to silica at levels 
greater than the preceding PEL of 100 [mu]g/m\3\ (Document ID 3251, p. 
2; 3296, p. 2; 3333, p. 2; 3373, p.2; 2503, p.2; 2291, p. 16; 4209, p. 
111). These commenters argued that OSHA did not attribute any costs to 
reaching 50 [mu]g/m\3\ to employers whose employees were exposed above 
100 [mu]g/m\3\. They argued that OSHA instead assumed that the costs 
and controls necessary to reach 100 [mu]g/m\3\ would also be sufficient 
to reach a level of 50 [mu]g/m\3\, and as discussed above, that OSHA 
did not account for those costs because reducing exposures to the 
preceding PEL of 100 [mu]g/m\3\ was already required before this 
rulemaking. The American Foundry Society (AFS) argued that OSHA reduced 
costs by two-thirds ``under the logic that employers must comply with 
the current PEL and the proposal does not add any existing obligation'' 
(Document ID 2379, Appendix 1, p. 10). AFS added that OSHA's 
underestimation of costs in this manner was particularly severe because 
OSHA used outdated data that showed more employees with exposures over 
100 [mu]g/m\3\, whereas more recent data would show fewer employees 
with exposures above 100 [mu]g/m\3\ and more with exposures between 50 
and 100 [mu]g/m\3\. Had OSHA used this updated data, in AFS's 
estimation, the Agency would have identified more employers needing to 
install additional engineering controls and thus there would be 
additional costs that were not accounted for in the PEA (Document ID 
2379, Attachment 3, pp. 9-10). ACC made a similar point, saying that as 
a result of OSHA's methodology, ``the exposure reduction costs for the 
estimated 81,000 workers now exposed above 100 [mu]g/m\3\ are not taken 
into account by OSHA on either a full cost basis or an incremental cost 
basis'' (Document ID 2308, Attachment 9, pp. 2-3).
    In addition URS, among others, argued that ``OSHA fails to account 
for the non-linear costs associated with each incremental reduction in 
silica concentrations,'' meaning that URS believed that it is more 
costly to achieve additional reductions in exposure as exposures are 
lowered. For example, according to URS's contention, it would be more 
costly to reduce exposures from 75 [mu]g/m\3\ to 50 [mu]g/m\3\ than 
from 125 [mu]g/m\3\ to 100 [mu]g/m\3\ (Document ID 2308--Attachment 8, 
p. 11; 2291, p. 16; 4209, p. 11; 2307, Attachment 2, pp. 181-182; 2379, 
Attachment 2, p. 9; 3487, p. 13).
    OSHA has several responses to these criticisms. In response to the 
criticism that OSHA overestimated the number of workers with exposure 
levels above 100 [mu]g/m\3\ as a result of using outdated data, the 
Agency has updated the exposure profile used to develop the final 
analysis of costs. This update is described previously in Chapters III 
and IV of the FEA. As a result of this update, OSHA found that, in the 
aggregate, the percentage of workers in general industry and maritime 
exposed to silica levels between 50 [mu]g/m\3\ and 100 [mu]g/m\3\ rose 
from 33 percent as estimated in the PEA to 42 percent. And, as the 
commenters noted would be the case, the percentage exposed at levels 
above 100 [mu]g/m\3\ fell from 67 percent to 58 percent. OSHA has 
updated this analysis to incorporate these data and has estimated costs 
for these additional workers whose exposures fall between 50 [mu]g/m\3\ 
and 100 [mu]g/m\3\. The revised distribution also shows that of those 
workers with exposures above the new PEL, 41 percent are exposed 
between the new PEL and the preceding general industry PEL with an 
average exposure level of 70 [mu]g/m\3\, 29 percent are exposed between 
the preceding PEL and 250 [mu]g/m\3\ with an average exposure level of 
156 [mu]g/m\3\, and 30 percent are exposed above 250 [mu]g/m\3\ with an 
average exposure level of 485 [mu]g/m\3\. Where an industry submitted 
more recent exposure data or information about exposure distributions 
within their industry, OSHA was able to show that its final exposure 
distribution was roughly equivalent (see Chapter IV of the FEA).
    The technological feasibility analysis (presented in Chapter IV of 
the FEA) describes the controls necessary for reducing exposures from 
the highest levels observed in an industry's exposure profile to the 
new PEL. In all application groups except two (asphalt paving products 
and dental laboratories), the highest observed exposures were above the 
preceding PEL. With the exception of hydraulic fracturing,\28\ the 
technological feasibility analysis did not distinguish between the 
controls necessary to meet the preceding general industry PEL of 100 
[mu]g/m\3\ and those necessary to meet the new general industry PEL of 
50 [mu]g/m\3\. Instead, the technological feasibility analysis simply 
listed the controls necessary for those employers whose employees had 
the highest baseline exposures to significantly reduce exposures and, 
in most operations, meet the new PEL.
---------------------------------------------------------------------------

    \28\ Due to an unusually rich data set, and the great similarity 
of different fracturing operations, both with respect to the 
equipment used and the current levels of control, OSHA was able to 
estimate which controls are necessary to go from an uncontrolled 
situation to the preceding PEL and which are necessary to get from 
the preceding PEL to the new PEL in the hydraulic fracturing 
industry.
---------------------------------------------------------------------------

    It was not necessary for OSHA to distinguish between controls 
necessary to achieve the preceding PEL and those necessary to achieve 
the new PEL in order to demonstrate the technological feasibility of 
achieving a PEL of 50 [mu]g/m\3\. Such a distinction would have been 
difficult because, from a baseline of uncontrolled exposures, the 
controls necessary to meet the preceding and new PELs are difficult to 
distinguish. For example, if there are two different controls necessary 
to fully meet the new PEL, then it is logically possible that two 
different establishments may achieve an exposure level at or below the 
preceding PEL in different ways. One establishment may have excellent 
housekeeping but poorly maintained LEV. Another may have well 
maintained LEV but poor housekeeping. For individual cases, there is 
not a simple demarcation of which controls of the total set of controls 
are necessary to achieve the new PEL when only the exposure level and 
not the controls already in place are known. Nor, as discussed above, 
is it the case that a control, once installed, will always provide 
identical protection. Two otherwise equal facilities may have the same 
installed controls but different exposure levels because of the quality 
of the maintenance of the system.
    For the purposes of costing engineering controls for general 
industry and maritime in the PEA, OSHA assigned all of the costs for 
meeting a PEL of 50 [mu]g/m\3\--including the costs of controls 
necessary to meet the preceding PEL of 100 [mu]g/m\3\--to all workers 
with exposure levels between 50 [mu]g/m\3\ and 100 [mu]g/m\3\. However, 
OSHA assigned no costs in the PEA to employees whose exposures exceeded 
the preceding PEL. This approach would be accurate for both those above 
and below the preceding PEL only if the exact same controls would be 
needed to control exposures in both situations and these controls would 
always yield an exposure level below the preceding PEL. However, as 
discussed in the previous section on proportionality of costs, OSHA has 
determined that this is not typically the case. There exist multiple 
kinds of controls and the actual application and operation of the 
control can differ. The approach applied in the PEA applied more 
controls than will typically be needed where exposures are below the 
preceding PEL and thus overestimates costs in these situations, but 
then assigns no costs for achieving

[[Page 16473]]

the new PEL where exposures are above the preceding PEL. In the latter 
situation, it can reasonably be expected that, in most cases, some 
costs would be incurred to meet the new PEL even after the preceding 
PEL is met and therefore the PEA methodology underestimated costs in 
those situations. Although these over- and under-estimates are 
partially offsetting, OSHA acknowledges that any over-estimates of cost 
do not necessarily offset the potential under-estimates of costs.
    OSHA has therefore decided to adopt an approach to the estimation 
of costs different from that adopted in the PEA. In the FEA, OSHA 
relied on data available in the rulemaking record to both correct the 
overestimate of costs for those below the preceding PEL and, as many 
industry commenters urged, estimate the costs necessary to meet the 
preceding PEL as well as the new PEL for those above the preceding PEL.
    To be clear, these data still do not enable OSHA to distinguish 
between the exact controls needed to get from uncontrolled exposures to 
the preceding PEL and those needed to get from the preceding PEL to the 
new PEL on an industry-by-industry and occupation-by-occupation basis. 
However, the data do enable OSHA to show that the majority of the costs 
of controlling silica exposures are incurred in order to reduce 
exposures from uncontrolled levels to the preceding PEL. OSHA will then 
assume that 50 percent of the costs incurred will be to implement the 
controls necessary to get from the uncontrolled situation to the 
preceding PEL and 50 percent to implement the controls necessary to go 
from the preceding PEL to meeting the new PEL. If, in fact, a majority 
of the costs are incurred in order to reduce exposures to the preceding 
PEL, the assumption that attributes 50 percent of costs to going from 
the preceding PEL to the new PEL will overestimate the true costs for 
establishments with exposures at the preceding PEL or between the 
preceding PEL and the new PEL.
    In order to assess whether the majority of the costs are necessary 
to meet the preceding PEL, OSHA first examined what kinds of exposures 
are associated with the uncontrolled situations that served as the 
starting point for the estimates of needed controls in the 
technological feasibility analysis. The average level of exposure 
across all of general industry for employees with exposure exceeding 
the preceding PEL is over 300 [mu]g/m\3\. Thus, on average, across all 
industries the uncontrolled situation involves high levels of exposure, 
commonly more than 3 times the preceding PEL.\29\
---------------------------------------------------------------------------

    \29\ To check that this was not the result of a very high 
exposures for a small number of employees or industries, OSHA 
examined the exposure profile presented in Table III-9 and found 
that in only 4 industries (with 1.1 percent of all employees exposed 
above the preceding PEL) were there no exposures above 250 [mu]g/
m\3\.
---------------------------------------------------------------------------

    In general, to reduce exposures from over 2.5 times the preceding 
PEL to the preceding PEL, employers would have to implement some 
measure or measures, and those measures would be the ones that provide 
the greatest reduction in silica exposures and therefore control most 
of the silica exposures in the facility. In most cases this will be a 
working LEV system or some form of worker isolation. Measures like 
improved housekeeping cannot reduce exposures from the levels observed 
in uncontrolled exposure situations to the preceding PEL. OSHA reviewed 
industry-by-industry and occupation-by-occupation cost estimates for 
engineering controls and found that, on average 63 percent of the costs 
were for LEV, 23 percent were for housekeeping, and 16 percent were for 
other controls, most commonly wet methods (based on OSHA, 2016). In 
many cases, where wet methods were applicable, wet methods represented 
the majority of the costs and there were not significant LEV costs. As 
a result, 79 percent of the costs of controls, on average, are 
attributable to either wet methods or LEV. The combination of LEV or 
wet methods with some improvement in housekeeping (though not the 
improvements necessary to meet the new PEL) will constitute the 
majority of costs for virtually all occupational categories. Some 
improvement in housekeeping will typically also be required to meet 
even the preceding PEL.\30\ While employers can probably meet the 
preceding PEL with less than ideally maintained LEV systems, 
improvements in maintenance will not reverse the conclusion that the 
majority of the costs are incurred to meet the preceding PEL. This is 
the case because on average 63 percent of engineering control costs are 
necessary to reach the preceding PEL and some housekeeping costs will 
also be necessary, leaving a significant percentage of expenditures 
above 50 percent of the costs available for improved maintenance.
---------------------------------------------------------------------------

    \30\ For example, in several industry sectors where workers are 
currently manually dumping silica-containing materials, the use of 
automated and ventilated dumping stations is needed to reduce 
exposures from over 250 [mu]g/m\3\ to below the preceding PEL. 
However, once these controls are installed and in use, final 
exposures are often below the limit of detection or less than 12 
[mu]g/m\3\--well below the new PEL (see technological feasibility 
chapter for paint and coatings). However, to maintain these 
exposures below the new PEL, these industry sectors will need to 
ensure that ventilation systems are properly maintained and will 
need sufficient housekeeping to ensure against build-ups of dust.
---------------------------------------------------------------------------

    To confirm the findings of this cost-spreadsheet-based analysis of 
where the majority of the costs are incurred, OSHA reviewed industries 
where good data are available on controls in both uncontrolled 
situations and situations with exposures between the new and the 
preceding PEL. OSHA examined the exposures and controls in eight 
ferrous sand casting foundry facilities. In these eight facilities, 
four had relatively few workers exposed above 50 [mu]g/m\3\, and the 
other 4 had many exposures over 100 [mu]g/m\3\. OSHA found that those 
facilities with most exposures over 100 [mu]g/m\3\ generally had little 
or no LEV (relying instead on general ventilation), poor housekeeping, 
no enclosures for workers, and poor maintenance. The foundries where 
silica dust was better controlled generally had working LEV systems, 
good housekeeping that kept surfaces free of silica dust, and good 
maintenance practices. This indicates that LEV and some housekeeping 
are essential to meeting the preceding PEL. OSHA also examined data on 
all exposures with control descriptions. These data showed that 
exposures above 250 [mu]g/m\3\ occurred in uncontrolled situations or 
situations in which controls, though installed, were not in use. In 
situations where exposures were between the preceding and new PELs, 
most exposures showed some controls in place, normally LEV, but not all 
controls recommended. In some cases there were no controls in place. 
These generally represented situations in which exposures were much 
lower than the typical uncontrolled situations and such facilities 
would not normally need the full controls necessary to go from very 
high levels of exposure to the new PEL (See Exhibit: Descriptions of 
Control, available in Docket OSHA-2010-0034 at www.regulations.gov).
    Based on these findings, OSHA determined that the majority of costs 
are incurred in order to implement controls necessary to get from an 
uncontrolled situation to the preceding PEL. However, OSHA developed 
cost estimates for engineering controls based on the conservative 
assumption that 50 percent of the total costs of going from an 
uncontrolled situation to the new PEL is incurred in order to reach the 
preceding PEL and the remaining 50 percent are incurred to reach the 
new

[[Page 16474]]

PEL.\31\ For example, in the cut stone industry 63 percent of those 
exposed above the new PEL are also above the preceding PEL and 37 
percent are below the preceding PEL but above the new PEL. The total 
cost to the cut stone industry of going from uncontrolled exposure to 
the new PEL is $17.7 million. With OSHA's assumption that half of the 
costs of going from an uncontrolled situation to the new PEL is 
incurred in order to reach the preceding PEL, then the cost for those 
employers with employees exposed above the preceding PEL would be 63 
percent of $17.5 million times 0.5, which equals $5.5 million. The cost 
for those below the preceding PEL would be 37 percent of $17.7 million 
times 0.5, which equal $3.3 million. The total cost of going from the 
preceding PEL to the new PEL in the cut stone industry is therefore the 
sum of these two calculations: $8.8 million. This will overestimate the 
costs of reaching the new PEL, given the majority of the costs are 
incurred to implement controls necessary to reach the preceding 
PEL.\32\
---------------------------------------------------------------------------

    \31\ This approach was not applied to the two industries, dental 
laboratories and asphalt paving materials, where the exposure 
profile showed that there were no exposures above the preceding PEL.
    \32\ OSHA also notes that this approach shows rising incremental 
costs of control, which is consistent with some comments. This is 
because 50 percent of the costs are estimated to be incurred to go 
from levels of over 250 [mu]g/m\3\ to 100 [mu]g/m\3\ and equal costs 
are estimated to be incurred to go from 100 [mu]g/m\3\ to 50 [mu]g/
m\3\.
---------------------------------------------------------------------------

    As presented in more detail below, this approach results in a total 
annualized cost estimate for general industry and maritime engineering 
controls of $225 million. Fortunately, this cost estimate is not highly 
sensitive to the allocation percentage chosen. Each decrement of 5 
percentage points changes the engineering control costs by 
approximately 5.5 percent. Thus, for example, if 65 percent of the 
costs are necessary to go from the preceding PEL to the new PEL, then 
the annualized cost estimate for engineering controls would rise to 
$261 million per year.\33\
---------------------------------------------------------------------------

    \33\ A value of 100 percent would be totally implausible as it 
would imply that all establishments currently far above the 
preceding PEL could achieve that PEL without cost. Put another way, 
this would be equivalent to saying that, if OSHA had decided to 
adopt the alternative PEL of 100 [mu]g/m\3\ (i.e., the same as the 
preceding general industry PEL), as some employer groups 
recommended, any employers currently above that PEL--regardless of 
how far above the PEL they were--would be able to meet a PEL of 100 
[mu]g/m\3\ without implementing any new engineering controls.
---------------------------------------------------------------------------

Accounting for Costs of Downtime
    Some commenters suggested that OSHA failed to account for the 
downtime that installing engineering controls or performing an initial 
through cleaning would require (e.g., Document ID 2368, p. 13 for 
engineering controls; Document ID 2379, Attachment 2, p. 16 for initial 
thorough cleaning).
    Almost all firms need downtime occasionally in order to perform 
general maintenance, inventory, or other tasks. In the final rule, OSHA 
has extended the compliance date for general industry from one year to 
two years. This will allow almost all employers to schedule work that 
might require downtime to install, improve, or maintain controls that 
they determine are necessary to meet the new PEL or to perform the 
initial thorough cleaning at times when they would already need 
scheduled downtime for other purposes. Therefore, OSHA has determined 
that there will be no additional costs incurred for downtime in order 
for employers to install engineering controls or to perform the initial 
thorough cleaning.
Technological Change
    One commenter, Dr. Ruth Ruttenberg, testifying for the AFL-CIO, 
argued that OSHA had overestimated costs by failing to consider 
technological change:

    Technological improvements--both engineering and scientific--are 
constantly occurring, especially when the pressure of a pending or 
existing regulation provide a strong incentive to find a way to 
comply at a lower cost. . . . These improvements are well-documented 
following the promulgation of rules for vinyl chloride, coke ovens, 
lead, asbestos, lock-out/tag-out, ethylene oxide, and a host of 
others (Document ID 2256, Attachment 4, p. 2).

    Dr. Ruttenberg recognized that OSHA, in the PEA, already predicted 
some ``technological and cost-saving advances with silica,'' such as 
expanding the use of automated processes and developing more effective 
bag seals, but criticized OSHA for not accounting for those cost 
savings in its analysis:

    Technological improvements are as sure a reality--based on past 
experience and academic research--as overestimation of cost and 
underestimate of benefits are in an OSHA regulatory analysis. More 
than 40 years of OSHA history bear this out (Document ID 2256, 
Attachment 4, p. 3).

    When promulgating health standards, OSHA generally takes an 
approach in which cost estimates and economic feasibility analyses are 
based on the technologies specified in the technological feasibility 
analysis. This is a conservative approach to satisfying OSHA's legal 
obligations to show economic and technological feasibility. As a 
result, the Agency does not account for some factors that may reduce 
costs, such as technological changes that reduce the costs of controls 
over time and improvements in production that reduce the number of 
employees exposed. As pointed out in the PEA, and from the examples 
described in the ``Total Cost Summary'' at the end of this chapter, 
some past experience suggests that these factors tend to result in 
OSHA's costs being overestimated.\34\ OSHA considers the primary 
purpose of the cost estimate to be to provide a basis for evaluating 
the economic feasibility of the rule, and OSHA has determined that for 
this rulemaking, feasibility is most accurately demonstrated by using 
an approach that does not account for the potential impacts of future 
technological changes.
---------------------------------------------------------------------------

    \34\ On the other hand, there is supplemental evidence from 
Harrington et al. (2000) [Harrington, Winston, Richard D. 
Morgenstern and Peter Nelson. ``On the Accuracy of Regulatory Cost 
Estimates.'' Journal of Policy Analysis and Management, 19(2), 297-
322, 2000] that OSHA does not systematically overestimate costs on a 
per-unit basis, and that the reason for overestimation of costs at 
the aggregate level has been a combination of difficulty with 
establishing baseline conditions and noncompliance. Nevertheless, 
several examples of OSHA's overestimation of costs reported in the 
article are due to technological improvements.
---------------------------------------------------------------------------

General Methodological Issues: Number of Workers Covered by a Control 
PEA Estimates
    The cost calculations in the PEA included estimates of the number 
of workers whose exposures are controlled by each engineering control. 
Because working arrangements vary within occupations and across 
facilities of different sizes, there are no definitive data on how many 
workers are likely to be covered by a given set of controls. In many 
small facilities, especially those that might operate only one shift 
per day, some controls will limit exposures for only a single worker. 
Also, small facilities might have only one worker in certain affected 
job categories. More commonly, however, and especially in the principal 
production operations, several workers are likely to derive exposure 
reductions from each engineering control.
    The PEA relied on case-specific judgments of the number of workers 
whose exposures are controlled by each engineering control (see Table 
3-3 in ERG, 2007b, Document ID 1608). The majority of controls were 
estimated to benefit four workers, based on the judgment that there is 
often multi-shift work and that many work stations are shared by at 
least two workers per shift. The costs of some types of equipment that 
protect multiple employees, such as HEPA vacuums, were spread over 
larger groups of employees (e.g., six to eight workers). In the PEA, 
the average number of workers affected represented

[[Page 16475]]

an average across all establishments, large and small.
Comments and Responses
    Some commenters questioned OSHA's estimate of the number of workers 
whose exposures could be controlled per newly added or enhanced 
control. OSHA's PEA most commonly estimated that four workers would 
have their exposures reduced for each new or enhanced engineering 
control. Dr. Ronald Bird, testifying for the Chamber of Commerce, 
argued that OSHA's estimates were simply arbitrary assumptions 
(Document ID 2368, p. 14). Stuart Sessions, testifying for the ACC, 
argued that the use of a single standard crew size of four led OSHA to 
underestimate costs and economic impacts for smaller establishments, at 
which, he argued, ``there are virtually never as many as four 
overexposed workers in any job category, and it is simply impossible 
that one application of a package of controls in this situation could 
protect as many as 4 overexposed workers on average'' (Document ID 
4231, Attachment 1, p. 6).
    The approach OSHA used was intended to represent the average number 
of employees affected by a given set of controls. Larger establishments 
may have more than four workers whose exposures are reduced by a single 
control, and smaller establishments may have fewer than four. However, 
OSHA agrees that this approach may result in an underestimate of costs 
for the smallest establishments. Because it is particularly important 
to consider the costs to the smallest establishments, OSHA has reduced 
the number of employees whose exposures are reduced per control by half 
for establishments with fewer than twenty employees, so that in those 
small establishments a given control is assumed to reduce exposures for 
two workers instead of four as assumed in the PEA. Because larger 
establishments may have greater numbers of employees whose exposures 
are reduced per control, this change may result in an overall 
overestimation of costs. (In the PEA, the overestimation of costs for 
larger facilities was partially offset by the underestimation of costs 
for smaller establishments. This is no longer the case in the FEA.) 
OSHA nevertheless believes the revised approach used in the FEA is 
better than the approach used in the PEA for purposes of capturing 
economic impacts on smaller establishments, even though it may result 
in aggregate costs being overestimated.
Variability
    Some commenters argued that both OSHA's technological feasibility 
and cost analyses were flawed because OSHA neglected to address the 
day-to-day variability of exposure measurements. By failing to address 
the issue of variability, these commenters argued, OSHA grossly 
underestimated the costs of engineering controls. These commenters 
reported that silica exposures would have to be controlled to levels 
considerably lower than the proposed (new) PEL in order to account for 
the variation in exposures across jobs and from day to day (e.g., 
Document ID 2307, Attachment 2, p. 202; 2308, Attachment 7, p. 2; 2308, 
Attachment 8, p. 6; 2379, Attachment 4, p. 1; 2291, p. 11; 2195, pp. 
26-27; 2503, p. 2; 2222, Attachment 1, p. 1). For example, in response 
to a written question about the activities in which employers were able 
to achieve the proposed (new) PEL ``most of the time,'' AFS objected to 
the premise of the question, noting that ``[s]everal foundries have 
received citations for exposures above the current PEL on operations or 
tasks for which the proposed PEL is achieved most of the time'' 
(Document ID 2379, Appendix 1, p. 18). AFS argued that OSHA's non-
compliance model of enforcement requires employers to reduce average 
exposures to half the PEL in order to have confidence that exposures 
will never exceed the PEL (Document ID 2379, Appendix 2, p. 29). The 
Asphalt Roofing Manufacturing Association (ARMA) made a similar point 
and said that the majority of asphalt roofing plants operated by its 
members have some exposures over the PEL of 50 [mu]g/m\3\, even if it's 
a ``relatively small incidence'' (Document ID 2291, p. 11).
    Both AFS and ARMA offered estimates of the magnitude of this 
variability by measuring the statistical variance of exposures. AFS 
stated that to assure 84 percent confidence in compliance with the 
preceding PEL, the mean exposures in some specific jobs in specific 
foundries would need to be below half that PEL, and that the ``mean 
level necessary to achieve the 95 percent confidence of compliance 
could not be determined but is significantly below one half the PEL'' 
(Document ID 2379, Appendix 1, p. 23).
    ARMA examined the distribution of silica exposures in over 1,300 
samples from 57 asphalt roofing facilities. These data showed that even 
though the median exposures for all jobs were below the new action 
level of 25 [mu]g/m\3\, a total of 9 percent of all samples were above 
the new PEL of 50 [mu]g/m\3\ (Document ID 2291, p. 5, Table 1). ARMA 
also provided an estimate of the ``lowest strictly achievable level'' 
(meaning a level not to be exceeded more than 5 percent of the time) 
which varied by job classification from 67 to 310 [mu]g/m\3\ (Document 
ID 2291, p. 9, Table 2).
    One serious problem with the ARMA analysis is that the discussions 
of variability and the estimates of mathematical variance are based on 
results either from different facilities with potentially different 
levels of controls or from all job categories within one facility. The 
key issue for assessing the importance of variability is the variance 
within a given job category in a specific establishment with specific 
controls. The methodology employed is such that even if individual job 
categories or individual facilities had no variance, pooling data 
across facilities would create variance.
    ARMA estimated that sufficiently controlling variation would 
require investment in capture vents, duct work, and dust collection 
systems costing up to $2.1 million each in initial costs per 
manufacturing line (Document ID 2291, p. 12). AFS did not provide a 
cost estimate solely for sufficiently controlling variation.
    The AFL-CIO disagreed with industry's arguments and instead argued 
that the best way to reduce variability was not simply to add 
additional engineering controls because, as explained earlier in the 
discussion of URS's comments on the per-worker cost basis, 
overexposures are not random:

    The worker-to-worker variation is explainable and controllable: 
Workers use different methods, they may take different positions 
relative to ventilation systems, they may use different work 
practices, and they may be subject to fugitive emissions (carryover 
from adjacent silica emitting processes). These differences in 
conditions can be observed by the industrial hygienist collecting 
the air sample, compared to exposure levels, and changed. Day-to-day 
variation for the same worker is caused by variation in materials, 
ventilation systems, production rate, and adjacent sources showing 
such variation. Sometimes these variations can be large, based on 
breakdowns of ventilation, process upsets and blowouts (Document ID 
4204, p. 40).

    OSHA's enforcement policies are discussed in Chapter IV of the FEA 
and in this preamble. Variability of exposures is potentially a cost 
issue when there are technologically feasible controls that have costs 
not otherwise accounted for that could further reduce environmental 
variability. If it is not technologically feasible to reduce 
variability then there will be no further costs. For example, if an 
employer has

[[Page 16476]]

installed all feasible controls, there are no additional costs for 
engineering controls because there are no additional controls to 
purchase, regardless of variability. On the other hand, an employer who 
has a median exposure level of 80 percent of the PEL with frequent 
excursions above and who could feasibly reduce variability would be 
required to do so.
    As noted above, those (AFS, ARMA) who argued that OSHA had 
underestimated costs by failing to account for exposure variability, in 
general, assumed that the best approach to reducing variability would 
be to increase the levels of LEV to reduce the average exposure level 
to half of the PEL or less, without examining the origin of the 
variability.
    OSHA agrees with the AFL-CIO that variability in exposure is likely 
controllable by examining the origins of the variability. One origin is 
poor work practices. To improve work practices, employers could observe 
work practices when monitoring takes place; determine which work 
practices are associated with high exposures; and modify those work 
practices found to lead to high exposures. Variability can also be the 
result of a failure of controls not functioning properly, either 
resulting from sudden failures or from gradual deterioration of 
performance over time. The latter can be prevented by good maintenance.
    Both in its cost assessment for the proposal and in the 
modifications made for this final rule, OSHA has taken account of the 
costs necessary to reduce unusual and exceptionally high exposure 
levels and thus reduce some sources of variation. As discussed in the 
cost of ancillary provisions, OSHA has estimated costs for exposure 
monitoring that include the time for observation of the worker. OSHA 
has also estimated costs for training to assure good work practices, 
and has increased the estimated length of training in general industry 
to ensure that the time is sufficient for training on work practices. 
In this section, OSHA has costed LEV, LEV maintenance, and the need for 
replacement LEV to assure that the LEV will function properly. OSHA has 
therefore already accounted for a variety of costs associated with 
steps that can be taken to reduce variability in exposures.
Substitution of Low- or Non-Silica Inputs
PEA Estimate
    For several industries, employers might lower silica exposures by 
substituting low- or non-silica inputs for existing inputs. While this 
option can be an extremely effective method for controlling silica 
exposures in many industries, OSHA did not cost this option in the PEA. 
OSHA determined that there were often complicating factors that 
restricted the potential for broad substitution of non-silica-
containing inputs for silica-containing inputs throughout the affected 
industries. It is possible that the same product quality cannot be 
maintained without using silica. Some products made with substitute 
ingredients were judged to be inferior in quality and potentially not 
viable in the market. In addition, a substitute silica ingredient might 
introduce adverse health risks of its own. Further, in several 
instances, the availability of reasonably inexpensive alternative non-
silica ingredients was well known but the alternative was not selected 
as a control option by most firms. In light of these concerns, OSHA 
decided not to include the option of non-silica substitutes in 
estimating the cost of the proposed rule.
Comments and Responses on Substitution
    Some commenters complained that OSHA's analysis did not account for 
the costs of substitution (Document ID 2264, Attachment 1, p. 27; 2379, 
Attachment 2, p. 6; 3485, p. 25; 3487, p. 17).
    OSHA considered the comments on the issue but has decided to adhere 
to the approach taken in the PEA. OSHA did not take account of the 
costs of substituting other substances for silica, because, while such 
substitution might have substantial benefits and avoid the need for 
engineering controls, OSHA determined that, in most situations, 
substitution is not the least costly method of achieving the proposed 
or new PEL (Document ID 2379, Attachment 2, p. 6). As a result, OSHA's 
final cost analyses do not account for the possibility that firms would 
choose to substitute for substances other than silica. To the extent 
that substitutes are the least costly solution in some situations, OSHA 
has overestimated the costs.
Cost of Air Quality Permit Notification
    The Agency received comments suggesting that foundries and other 
manufacturing plants would be required by the Environmental Protection 
Agency (EPA), or other federal or state environmental authorities, to 
incur an administrative cost to ensure their systems are compliant with 
relevant EPA regulations. Commenters expressed concern that the 
permitting process itself could be a major undertaking, made worse by 
difficult compliance deadlines. Given that the final rule provides 
extra time for planning and permitting, OSHA has examined the potential 
impacts of the new rule and finds that the commenters are overstating 
the potential for such costs. The argument for significant permitting 
costs was typically combined (e.g., Document ID 2379, Appendix 3) with 
an argument that the Agency underestimated the amount of ventilation 
required to comply with the final rule; comments on ventilation 
requirements are dealt with in great detail elsewhere in this chapter.
    Upon investigation, while OSHA agrees that it would be appropriate 
to recognize an administrative burden with respect to the interfacing 
environmental regulations, the Agency believes that many of the 
commenters' concerns were overstated. First, many control methods 
needed to comply with the final rule will not require alterations to 
existing ventilation systems. As discussed earlier in Chapter V of the 
FEA, work practices, housekeeping and maintenance are important 
components in controlling exposures; in many cases existing 
ventilation, as designed and permitted with the environmental 
authority, is adequate, but needs to be maintained better. In addition, 
most establishments, particularly smaller ones, will continue to have 
particulate emissions levels that fall below the level of EPA permit 
requirements. In the case of large facilities that do not, the changes 
will be on a sufficiently small scale that they will not require 
elaborate repermitting, but will only require minor incremental costs 
for notifying the environmental authorities, or in some cases, 
submitting a ``minor'' permit (see http://www2.epa.gov/nsr and http://www2.epa.gov/title-v-operating-permits). Taking into account the 
preceding silica PEL and the estimate that baghouses will capture 99 
percent of silica emissions (Document ID 3641, p. VII-19), OSHA 
concludes that it is unlikely that facilities will encounter a need for 
significant air permit modifications.
    The Agency recognizes, however, that there will be minor 
incremental costs for notifying environmental authorities. While many 
establishments in the United States may have no requirement to do so, 
the Agency has conservatively assumed that all establishments with 
twenty or more employees in most industries will need to dedicate a 
certain amount of time to preparing a one-time notification to 
environmental authorities to ensure that their air permits accurately 
reflect current operating conditions. OSHA has determined that small 
establishments

[[Page 16477]]

would generally lack the large scale industrial facilities requiring 
permits, and that the few that might require such permits would be 
balanced out by the likely inclusion of medium establishments that do 
not actually require permits for their emissions. The industries 
excluded were those that generally lack large scale industrial 
facilities, or that do not produce a concentrated, as opposed to 
diverse or unconsolidated, emission source. The excluded industries 
were hydraulic fracturing, shipyards, dental equipment and labs, 
jewelry, railroads, and landscaping.
    To allow for adequate administrative time for creating and 
submitting the notification, at those facilities that could potentially 
incur costs, OSHA allocated 20 hours to establishments with 20 to 499 
employees and 40 hours to establishments with 500 or more employees. A 
manager's loaded hourly wage rate of $74.97 was applied to estimate the 
cost to employers (BLS, OES, 2012, Document ID 1560). The costs per 
establishment were estimated at approximately $1,500 per medium 
establishment and $3,000 per large establishment. Because both new 
permit applications and permit modifications are minor administrative 
chores, OSHA's cost estimates are sufficient to cover either case.
Costs for Specific Engineering Controls
Ventilation Costs
PEA Estimates
    In the PEA, OSHA determined that at many workstations, employers 
needed to improve ventilation to reduce silica exposures. The cost of 
ventilation enhancements estimated in the PEA generally reflected the 
expense of ductwork and other equipment for the immediate workstation 
or individual location and, potentially, the cost of incremental 
capacity system-wide enhancements and increased operating costs for the 
heating, ventilation, and air conditioning (HVAC) system for the 
facility.
    In considering the specific ventilation enhancements for given job 
categories the PEA estimated the type of LEV and the approximate 
quantity in cubic feet per minute (cfm) of air flow required to reduce 
worker exposures.
    To develop generally applicable ventilation cost estimates for the 
PEA, a set of workstation-specific and facility-wide ventilation 
estimates were defined using suggested ventilation approaches described 
in the American Conference of Governmental Industrial Hygienists 
(ACGIH) Industrial Ventilation Manual, 24th edition (Document ID 1607). 
With the assistance of industrial hygienists and plant ventilation 
engineering specialists, workstation estimates of cfm were derived from 
the ACGIH Ventilation Manual, and where not covered in that source, 
from expert judgements for the purpose of costing LEV enhancements 
(Document ID 1608, p. 29).
    Over a wide range of circumstances, ventilation enhancement costs, 
which included a cost factor for HEPA filters and baghouses, where 
needed, varied from roughly $9 per cfm to approximately $18 per cfm 
(Document ID 1608, p. 29). Because of a lack of detailed data to 
estimate the specific ventilation installation costs for a given 
facility, an estimate of the likely average capital cost per cfm was 
used and applied to all ventilation enhancements. Based on discussions 
with ventilation specialists, $12.83 per cfm was judged to be a 
reasonable overall estimate of the likely capital costs of ventilation 
enhancements (Document ID 3983, p. 1).
    OSHA applied the per-cfm capital cost estimate to estimated cfm 
requirements for each workstation. By using the unit value of $12.83 
per cfm, the cost estimates for each ventilation enhancement included 
both the cost of the LEV enhancement at the workstation and the 
contribution of the enhancement to the overall facility ventilation 
system requirements. That is, each ventilation enhancement at a 
workstation was expected to generate costs to the building's general 
ventilation system either by requiring increased capacity to make up 
for the air removed by the LEV system or to filter the air before 
returning it to the workplace.
    For operating costs, engineering consultants analyzed the costs of 
heating and cooling system operation for 12 geographically (and 
therefore, climatologically) diverse U.S. cities. The analysis, 
presented in Table 3-2 in the ERG report (Document ID 1608, p. 30), 
showed the heating and cooling British Thermal Unit (BTU) requirements 
for 60-hours-a-week operation (12 hours a day, Monday through Friday) 
or for a continuous 24-hour-a-day, year-round operation, with and 
without recirculation of plant air. Facilities that recirculate air 
have much lower ventilation system operating costs because they do not 
need to heat or cool outside air to comfortable inside temperatures.
    In the PEA, ventilation operating costs were based on a weighted 
average of the costs of four operating scenarios: (1) No recirculated 
air, continuous operation; (2) no recirculated air, operating 60 hours 
per week; (3) recirculated HEPA filtered air, continuous operation; and 
(4) recirculated HEPA filtered air, operating 60 hours per week. These 
scenarios were chosen to reflect the various types of operating system 
characteristics likely to be found among affected facilities. The 
weights (representing the share of total facilities falling into each 
category) and operating costs per cfm for each of these scenarios are 
shown below in Table VII-11-1:

[[Page 16478]]

[GRAPHIC] [TIFF OMITTED] TR25MR16.051

    The national average annual operating cost per cfm was estimated to 
be $2.22. This estimate was a weighted average of the operating costs 
for facilities that recirculate air and those that require make-up air. 
The operating costs for HEPA-filter recirculated air were estimated at 
$0.50 per cfm for facilities operating 60 hours per week and $1.40 per 
cfm for those continuously operating 24 hours per day. The operating 
costs for facilities that do not recirculate air were $5.78 per cfm for 
those operating 60 hours per week and $15.55 per cfm for those 
operating continuously. In generating these estimates, it was judged 
that 80 percent of facilities would recirculate airflow and 20 percent 
would not, and that 75 percent within each group operate for 12 hours 
per day on weekdays, with the remainder operating continuously, year-
round, for 24 hours a day.
    OSHA also added a maintenance factor to the operating cost 
estimates, which was 10 percent of the capital cost investments of 
$12.83 per cfm for ventilation systems. As a result, the total annual 
costs per cfm, excluding annualized capital costs, were estimated to be 
$3.50 (weighted average operating costs of $2.22 plus annual 
maintenance costs of 10 percent of $12.83).
    Underlying the cost results was the assumption that, over the 
course of the proposed one-year compliance period for engineering 
controls, employers would schedule installation of ventilation to 
minimize disruption of production, just as they would with any 
modification to their plants.
Comments and Responses on Local Exhaust Ventilation Issues: Need for a 
Complete New System
    Local exhaust ventilation represents one of the major costs 
associated with engineering controls in both the PEA and in the FEA. 
Commenters raised issues both about OSHA's PEA estimates of the unit 
costs of LEV and about the adequacy of OSHA's estimates of the volume 
of LEV that would be needed to adequately control silica exposures.
    URS, testifying on behalf of ACC, argued that any firm that would 
be utilizing LEV to meet a PEL of 50 [mu]g/m\3\ would need to remove 
any existing LEV and install an entirely new LEV system. Thus, in URS's 
estimation, there would be no incremental addition of LEV. In a 
discussion of the URS approach during OSHA's informal public hearings, 
OSHA asked the URS representative to confirm that his organization 
commented that when a majority of workers are exposed over the PEL, the 
existing controls must be replaced instead of enhanced:

    MR. BURT: I want to be sure I understand what that's saying. 
Let's say you encountered a situation in which there were four 
workers. Two were exposed at 35, two at 60. You would scrap all of 
the controls and start over again. That's what it seems to be 
saying.
    [. . .]
    MR. WAGGENER: [Y]es, that they would need to be replaced with a 
more adequate system (Document ID 3582, Tr. 2109-2110).

    OSHA's examination of the spreadsheets URS provided documenting its 
independently developed cost estimates shows that, in all cases where 
any employee in an establishment was exposed above 50 [mu]g/m\3\, URS 
assumed that the employer would need to install a complete new LEV 
system and included the costs for installing and operating this 
entirely new system (Document ID 2308, Attachment 8, pp. 13-14).
    John Burke from OSCO Industries took a different approach to the 
question that better illustrates the options that OSHA believed to be 
available when it developed the PEA estimates:

    A single large dust collector is probably already handling the 
exhausting of the entire sand conditioning system. Most likely all 
the pick-up points referenced in the economic analysis already have 
suction being applied and yet there is still an overexposure. What 
do you do and how much is that going to cost? If the sand system 
operator is overexposed then you could first evaluate work practices 
controls. If work practice controls are unsuccessful and additional 
suction is needed, that suction is going to be very expensive! If 
your environmental operating permit allows it you may be able to 
tweak the performance of the dust collector. There may be some 
things you can

[[Page 16479]]

do to tweak the capacity of your existing dust collector to bring it 
up to exactly its permitted air volume or you might have to enlarge 
your dust collector (Document ID 1992, p. 6).

    OSHA agrees with Mr. Burke. As discussed above, there are usually a 
wide variety of ways to improve existing controls before removing and 
reinstalling an LEV system. As a result, OSHA finds the URS approach 
unrealistic and likely to significantly overestimate costs.
Comments and Responses on the Volume of Controls Needed
    One commenter, URS, questioned OSHA's estimates of the volume of 
additional LEV that would be needed to comply with the standard. URS, 
testifying for ACC, reported that OSHA's estimates in the PEA were too 
low as compared to the recommendations in Table 6-2 of the ACGIH 
Ventilation Manual (28th Edition). They criticized OSHA's estimates 
saying that OSHA routinely underestimated required capture velocities 
by at least a factor of two for particles with high (conveyor loading, 
crushing) or very high (grinding, abrasive blasting, tumbling) energies 
of dispersion (Document ID 2308, Attachment 8, pp. 12 and 14). URS said 
that ``the capture velocities for LEV systems in OSHA's models were 
often based on the minimum recommended velocity,'' that OSHA's 
estimated additional LEV was too low because ``the ACGIH capture 
velocity values used by OSHA were first developed and published many 
years ago'' and were not sufficient to control dust to the levels OSHA 
is now proposing, and that ``the velocity values used in OSHA's cost 
model are most likely undersized by a factor of 2 or more'' (Document 
ID 2308, pp. 11-12). Other than its own supposition, URS did not 
identify an alternative source for OSHA to use as the basis for 
estimates of ventilation capacity necessary to control silica 
exposures.
    In response to these comments, and in order to determine whether 
ACGIH recommendations had changed between the 24th edition (which OSHA 
used to develop estimates in the PEA) and the more recent 28th edition, 
OSHA checked its estimated volumes against those in the more recent 
ACGIH Ventilation Manual (Chapter 13 in the 28th edition (Document ID 
3883)). In the 24th edition of the Manual, ACGIH provided a single 
recommendation for ventilation capacity rather than a range. In the 
PEA, OSHA adopted this recommendation and did not choose a value from 
within a range of values. The 28th edition of the Manual provides more 
flexibility in system design and specification and incorporates a 
recommended range. However, OSHA determined that the ventilation 
capacity estimates did not change between the 24th edition of the 
Manual and the 28th edition. In most cases, OSHA's estimated volumes 
were identical to those recommended by ACGIH. The exceptions were 
situations in which ACGIH provided no recommendation (in which case 
OSHA relied on recommendations of industrial hygienists), and 
situations in which the technological feasibility analysis recommended 
additional volumes of LEV capacity above what employers were typically 
using. In the latter situations, OSHA estimated that an additional 25 
percent of the ACGIH specification would be necessary to adequately 
control silica exposures (See Exhibit: Comparison of OSHA CFM Volumes 
to ACGIH Values, available in Docket OSHA-2010-0034 at 
www.regulations.gov).
    URS argued that silica was different from other substances LEV 
might be applied to in ways that would call for higher volumes of 
ventilation (Document ID 2308, Attachment 8, p. 14). However, in all 
cases involving silica (such as shake-out stations), the ACGIH Manual 
recommended the volumes used by OSHA and criticized by URS.
    OSHA's estimates of the ventilation capacity necessary to control 
silica exposures relied on a detailed set of recommendations provided 
by ACGIH while URS simply asserted that these values are ``most likely 
undersized by a factor of 2 or more'' without providing additional 
evidence to support this (Document ID 2308, Attachment 8, p. 12). Based 
on these findings, OSHA has determined that the ACGIH recommendations 
constitute the best available evidence and has maintained the estimates 
of ventilation capacity from the PEA for the FEA.
Comments Providing Alternative Ventilation System Cost Estimates
    Other commenters provided much higher costs than OSHA's estimates 
but without providing any background to allow OSHA to put those costs 
in context. It is difficult for OSHA to evaluate a cost estimate 
without information on the size of the facility, the estimated volume 
of air, and the exposure levels before and after the LEV was installed.
    The Interlocking Concrete Pavement Institute (ICPI) commented that 
OSHA underestimated compliance costs because ``[o]ne ICP manufacturer 
reported that it could cost $150,000 to acquire and install highly 
efficient vacuum and water dust-control systems'' and other 
manufacturers reported similarly high costs (Document ID 2246, p. 11). 
At the public hearings, OSHA sought clarification on the assumptions 
underlying the ICPI cost estimate, and the ICPI representative stated 
that $150,000 was a mid-range estimate. The representative also 
confirmed that this was the cost of an entirely new system:

    MR. BLICKSILVER: [D]oes this actually represent the incremental 
cost associated with complying with OSHA's proposed rule? . . . Or 
is this an overall cost for dust control in these manufacturing 
plants?
    MR. SMITH: The latter (Document ID 3589, Tr. 4407-4409).

    In a follow-up verbal exchange, OSHA requested that ICPI analyze 
its survey data to produce median values for the range of cost 
estimates and submit their analysis as a post-hearing comment (Document 
ID 3589, Tr. 4409). However, no ICPI comments appeared in the record 
following the Institute's testimony at the hearings.
    Similarly, OSHA asked Mr. Tom Slavin, testifying for AFS, for 
additional information from AFS on the many cost estimates for 
individual foundries that it had included in its comments:

    MR. BURT: You provide many examples of cost to specific 
foundries of specific activities. I would like to suggest that those 
can be most useful if we have data on the size of the firm in 
question, the type of foundry if that's appropriate, and what they 
were trying to accomplish with this effort.
    Were they at 400 and trying to get to 100, at 100 trying to get 
lower? Something that puts it in context would again make these 
many, many helpful quotes much more useful.
    Size is just critical, just because of the fact that when we 
don't know whether we're talking about 20 or 200 people in a foundry 
really affects what you want to do with those cost estimates. And 
that one's relatively simple, size of firm, type of foundry if you 
have it, what they were trying to do with that effort (Document ID 
3584, Tr. 2773-2774).

    Later in the exchange, OSHA requested information on ``the 
components of [AFS's estimated cost per cfm of additional ventilation] 
that would be capital cost, installation cost, and then any other 
operating costs you have'' (Document ID 3584, Tr. 2784). OSHA received 
no response to this request.
    Unfortunately, it is almost impossible for OSHA to make use of 
commenters' estimates of costs or volume of LEV systems without 
information on the size of the facility and on what the resulting 
system accomplished in terms of reducing exposure levels. OSHA 
consistently requested this kind of

[[Page 16480]]

information, but did not receive it. As shown in the discussion of 
alternative estimates of costs by small entity representatives during 
the SBAR Panel (discussed below), even estimates that appear higher 
than OSHA's average costs can be consistent with those costs when the 
full context for the estimates is examined.
Comments and Responses on Unit Cost per CFM
    Many commenters thought that OSHA's unit costs for ventilation were 
too low. With respect to the annualized value of the capital costs plus 
operating and maintenance costs of $5.33 that OSHA used in the PEA, AFS 
stated:

    The PEA uses an annual cost factor of $5.33 for ventilation, 
including ducting and bag house operation [...] is far below foundry 
experience. A group of foundry ventilation managers and ventilation 
experts estimated the annual cost per CFM at $20 for exhaust alone 
and another $6-10 for makeup air critical to achieving the lower 
PEL. The cost to meet the new U.S. Environmental Protection Agency 
(EPA) dust loading criteria increases the exhaust annual cost to $25 
per CFM. Any new installation would be expected to design to the new 
criteria even if not yet required to do so for that specific 
jurisdiction (Document ID 2379, Appendix 3, p. 9).

    URS, commenting on behalf of ACC, estimated the annualized cost of 
LEV to be $27 per cfm, and increased OSHA's original estimate of 
capital costs from $12.83 to $22 per cfm for the purpose of URS's cost 
estimate (Document ID 2308, Attachment 8, pp. 13-14).
    Many other commenters from industry suggested unit costs for 
additional LEV. For example, AFS provided independent estimates of 
annualized costs of $20 to $25 per cfm and URS estimated $22 to $27 
capital costs per cfm (Document ID 2379, Appendix 1, p. 45; 2308, 
Attachment 8, p. 14; 2379, Appendix 2, p. 13; 2503, p. 2; 2119, 
Attachment 3, p. 4; 2248, p. 8; 3490, p. 3; 3584, Tr. 2779).
    OSHA agrees that there can be a wide range of both capital and 
operating costs associated with LEV. Capital costs will vary according 
to such factors as the exact nature of the ventilation (including the 
design of the slot, hood, or bagging station), the volume of materials 
to be handled by the ventilation, and the length of the ductwork 
necessary. OSHA also would like to clarify that, as shown in OSHA's 
spreadsheets (OSHA, 2016), where there are major structural changes 
associated with a control, such as automation, a new bagging station, 
or conveyor closure, these costs are estimated over and above the basic 
capital costs of LEV. Annual operating costs vary according to climate, 
hours of operation, and the extent to which air is recirculated. To 
examine these possible costs, OSHA reviewed the thoroughly documented 
LEV costs presented in its Final Economic Analysis for the Occupational 
Exposure to Hexavalent Chromium Standard (Document ID 3641). In that 
FEA, OSHA's estimates of the capital costs for LEV (updated to 2012 
dollars) averaged more than $20 per cfm when major work station 
changes, such as automated bag slitting stations, were included in the 
cost of LEV. Ordinary additional LEV without major workstation changes 
was estimated to have an average capital cost of $9 per cfm in 2012 
dollars. Operating costs in that rulemaking were estimated to be 
somewhat higher than estimated here, but combined annualized costs 
(capital plus operating costs) were approximately the same (See 
Exhibit: Analysis of LEV Costs from Hex Chrome, available in Docket 
OSHA-2010-0034 at www.regulations.gov).
    OSHA agrees that the capital costs of some kinds of LEV that 
involve significant workstation modifications or even automation can 
exceed $20 per cfm, but finds an average of $13.34 (in 2012 dollars) 
per cfm in capital costs to be reasonable given that some kinds of LEV 
installation can cost as little as $3 to $5 per cfm. OSHA also finds 
the operating cost estimates used in the FEA to be a reasonable average 
across a very wide variety of circumstances.
Housekeeping and Dust Suppression Costs
PEA Costs
    For a number of occupations, the technological feasibility analysis 
in the PEA indicated that improved housekeeping practices were needed 
to reduce silica exposures. The degree of incremental housekeeping 
depended upon how dusty the operations were and the appropriate 
equipment for addressing the dust problem. The incremental costs for 
most such occupations reflected labor associated with additional 
housekeeping efforts. Because incremental housekeeping labor was 
required on virtually every work shift by most of the affected 
occupations, the costs of housekeeping in the PEA were significant. The 
PEA also estimated that employers would need to purchase HEPA vacuums 
and to incur the ongoing costs of HEPA vacuum filters. The time needed 
for such housekeeping varied from five to twenty minutes per affected 
worker per day. Appendix V-A in the PEA provided detailed 
specifications on the application of housekeeping and other dust-
suppression controls in each occupational category and the sources of 
OSHA's unit cost data for such controls.
    For some indoor dust suppression tasks, it was assumed that dust 
suppression mixes--often sawdust-based with oil or other material that 
adheres to dust and allows it to be swept up without becoming 
airborne--were spread over the areas to be swept. For these products, 
estimates were made of usage rates and the incremental times necessary 
to employ them in housekeeping tasks.
    For outdoor dust suppression, the PEA determined that workers must 
often spray water over storage piles and raw material receiving areas. 
The methods by which water is provided for these tasks can vary widely, 
from water trucks to available hoses. It was judged that most 
facilities would make hoses available for spraying and that spraying 
requires a materials-handling worker to devote part of the workday to 
lightly spray the area for dust control.
    The PEA did not include any costs for thorough cleaning designed to 
remove accumulated dust, either as a one-time cost or as an annual 
cost.
Comments and Responses on Costs of Routine Housekeeping and Initial 
Cleaning
    Commenters had a number of issues with respect to how OSHA treated 
the costs of housekeeping, including the time and equipment needed for 
vacuuming, the need for professional floor to ceiling cleaning, and the 
costs of the ban on dry sweeping.
Comments and Responses on Costs of Routine Housekeeping
    With respect to the use of HEPA vacuums, AFS commented that due to 
the volume of sand involved, foundries often use vacuum systems that 
cost $45,000 instead of the $3,500 estimated by OSHA in the PEA 
(Document ID 4229, Attachment 1, p. 23). Several commenters reported 
that HEPA semi-mobile central vacuum systems cost more than $40,000 to 
purchase and cost approximately $4,000 per year to maintain, and that 
sweeping compound costs approximately $4,000 per year (Document ID 
2384, p. 7; 2114, Attachment 1, p. 4). Several others noted that 
acquiring HEPA vacuums and employee time for vacuuming would be 
expensive (Document ID 2301, Attachment 1, p. 74; 3300, pp. 4-5; 2114, 
Attachment 1, p. 4).
    OSHA's costs are for improved housekeeping, beyond the necessary 
tasks related to dealing with the large volumes of sand used in 
foundries. For this final rule, OSHA estimates the costs

[[Page 16481]]

of additional housekeeping as those necessary for overexposed workers 
to spend 10 minutes vacuuming their immediate work areas with a 15-
gallon HEPA vacuum. It is possible that a large firm may find a dust 
handling system or a semi-mobile central vacuum system less expensive 
than having individual workers equipped with smaller capacity HEPA 
vacuums spend additional time performing housekeeping on each shift.
    With respect to the shipbuilding sector, OSHA found that it had not 
accounted for the costs of HEPA vacuums for abrasive blasting helpers. 
OSHA has added costs for the vacuums, but not for the time spent 
performing housekeeping as the vacuums replace dry sweeping.
    As to the possible costs of the ban on dry sweeping, OSHA has 
modified this prohibition in ways that should avoid significant costs 
in situations where dry sweeping is the only effective method of 
housekeeping.
Comments and Responses on Costs of Initial Cleaning
    URS, testifying for ACC, questioned OSHA's omission of 
``professional cleaning'' from its cost models for some industries, 
noting that professional cleaning was identified in the PEA as 
necessary for some industries to achieve the PEL (Document ID 2308, 
Attachment 8, p. 12). URS also provided estimates of the cost of 
professional cleaning:

    Based on communications with several industries, URS estimates 
that a thorough annual professional cleaning will cost about $1.00 
per square foot of the facility process operations area.
    . . . A professional cleaning can take several days to 
accomplish [. . .] For square footage, URS assumed 20,000 square 
feet for very small facilities, 50,000 square feet for small 
facilities, and 200,000 square feet for large facilities (Document 
ID 2308, Attachment 8, p. 24).

    Initial thorough facility cleaning and rigorous housekeeping are 
supplemental controls and work practices addressed in the technological 
feasibility analysis for the following application groups: Concrete 
Products, Pottery, Structural Clay, Mineral Processing, Iron Foundries, 
Nonferrous Sand Foundries, and Captive Foundries. OSHA failed to 
include the costs of a thorough initial cleaning in the PEA, but has 
developed estimates of these costs for the FEA in response to the URS 
comment. The final standard sets the performance objective of achieving 
the PEL using engineering controls, work practices, and where 
necessary, respiratory protection, and, with respect to facility 
cleaning and housekeeping, the rule does not mandate that firms hire 
outside specialists. To estimate the final costs for initial thorough 
facility cleaning, OSHA first developed an analysis of average 
production floor space in square feet for two plant sizes based on data 
on plant floor space and employment for individual facilities reported 
in various NIOSH control technology and exposure assessment field 
studies (OSHA examined Document ID 215; 216; 268; 1373; 1383; 3786; 
3996; and 4114. The analysis is in Exhibit: Analysis of Plant Floor 
Space, available in Docket OSHA-2010-0034 at www.regulations.gov).
    For the purpose of estimating cleaning costs, OSHA characterized 
establishments with fewer than twenty employees as very small 
establishments, and characterized establishments with twenty or more 
employees as larger establishments.
    OSHA determined, based on a review of the data in the NIOSH field 
studies, that production floor space averages 725 square feet per 
employee (See Exhibit: Analysis of Plant Floor Space).
    For very small establishments with fewer than 20 employees, OSHA 
used an average of 7 employees per establishment. For larger 
establishments, OSHA used an average of 80 employees. (These estimates 
of the number of employees are based on OSHA (2016), which shows that 
the average number of employees for establishments with fewer than 20 
employees is 7 employees and that the average number of employees for 
establishments with more than 20 employees is 80 employees.) Based on 
these parameters, OSHA's floor space model found that the typical floor 
space for very small establishments is 5,075 square feet and for larger 
establishments is 58,000 square feet.
    ERG spoke with a representative of an upper-Midwestern firm 
specializing in the industrial cleaning of foundries and related 
facilities (Document ID 3817, p. 2). According to that representative, 
cleaning costs depend on numerous factors, such as the distance to the 
facility that needs to be cleaned, the size and number of machines and 
pieces of equipment present, the types of required cleaning activities, 
and the presence of confined spaces. The representative described one 
of his company's clients as a sand-casting foundry that produces 42,000 
tons of gray and ductile iron castings per year in a 210,000 square 
foot facility. According to the representative, a crew of two 
technicians cleans the facility every 2 to 3 weeks at a cost of $2,200 
to $3,500 per cleaning, which requires one day, or roughly $0.01 to 
$0.02 per square foot in 2014 dollars.
    For the FEA, OSHA is estimating, based on data from the ERG field 
interviews, that it will take 4 to 5 days to perform a one-time initial 
cleaning (remove all visible silica dust) and that if the same facility 
is cleaned every 2 to 3 weeks it will take 1 day to clean it. At a cost 
of $0.02 per day per square foot, and using a cleaning duration of 5 
days, OSHA calculated a cost of $0.15 per square foot in 2012 dollars 
for an initial thorough cleaning. This value is derived from inflating 
the 2003 estimate of $0.10 per square foot ($0.02 per day per square 
foot over 5 days) to 2012 dollars, which raised the cost to $0.12 per 
square foot. OSHA also allowed for an additional allotment of 25 
percent of the estimated cost of $0.12 per square foot (in 2012 
dollars) to ensure that the cleaning was sufficiently thorough to 
achieve compliance, increasing the total from $0.12 to $0.15. OSHA 
judges that this is a reasonable average for the range of facilities to 
be covered, especially given that some annual cleaning is probably 
already occurring at most facilities and therefore the full cost of 
cleaning would not be attributable to this rule. The costs here are 
applied to represent an incremental cleaning beyond that employed for 
normal business purposes.
    As discussed earlier in this chapter, URS, an engineering 
consultant to ACC, estimated that a thorough annual professional 
cleaning will cost about $1.00 per square foot of a facility's process 
operations area. URS provided no specific reference for that unit 
estimate other than that it communicated with industry representatives 
(Document ID 2308, Attachment 8, p. 24). The data OSHA used to develop 
its cost estimates are based on interviews with a company that provides 
housekeeping services rather than companies that may or may not have 
purchased such services. OSHA's estimated costs for a thorough initial 
cleaning are over five times the costs of a thorough cleaning where 
there is just few weeks' worth of accumulated dust. Greater 
accumulations during an initial cleaning do not mean that the initial 
cleaning will cost 50 times the cost of a more basic/regular cleaning, 
as much of the cost of the initial cleaning will be due to the time 
spent going over the entire facility with the appropriate cleaning 
devices--a cost that is fixed by area and not by accumulation. OSHA 
therefore rejects the URS unit estimate of $1.00 per square foot as not 
representative of a typical cost for initial thorough facility 
cleaning, particularly for firms that choose to use in-house resources. 
Nonetheless, OSHA

[[Page 16482]]

acknowledges that unique circumstances may create higher unit costs 
than the value OSHA is using in the FEA. OSHA also acknowledges that 
the cost of cleaning per square foot probably declines as facility size 
increases (Document ID 4231, p. 4). The paucity of data on square 
footage for the affected facilities, however, did not allow for further 
modeling of cleaning costs.
    For this final analysis of costs for initial thorough facility 
cleaning, OSHA estimated that an upfront, one-time, extensive servicing 
(using vacuum and wash equipment) to rid the production area of 
respirable crystalline silica during plant turnaround or other downtime 
would cost $0.15 per square foot (including the additional allowance to 
ensure a sufficiently thorough cleaning) or $0.02 when annualized at 3 
percent for 10 years, and OSHA applied that unit cost along with the 
average production floor space discussed above in OSHA's cost model 
(725 square feet per employee) to derive final costs for facility 
cleaning by application group. For the seven affected application 
groups, OSHA estimates that annualized initial thorough facility 
cleaning costs will range from just under $45,000 for Nonferrous Sand 
Foundries to $488,000 for Concrete Products. Across all seven affected 
application groups, OSHA estimates that annualized costs for initial 
thorough facility cleaning will total $2.8 million.
Conveyor Covers
    The technological feasibility analysis in the PEA recommended 
reducing silica exposures by enclosing process equipment, such as 
conveyors, particularly where silica-containing materials were 
transferred (and notable quantities of dust can become airborne), or 
where dust is generated, such as in sawing or grinding operations. For 
the PEA, OSHA estimated the capital costs of conveyor covers as $20.73 
(updated to 21012 dollars) per linear foot, based on Landola (2003, 
Document ID 0745) (as summarized in footnote a in Table V-3 of the 
PEA). OSHA estimated that each work crew of four affected workers would 
require 100 linear feet of conveyors. OSHA, based on ERG's estimates, 
calculated maintenance costs as 10 percent of capital costs. Based on 
the technological feasibility analysis, OSHA also included the cost of 
LEV on the vents of the conveyors for the structural clay, foundry, 
asphalt roofing, and mineral processing application groups, but not for 
the glass and mineral wool application groups.
    URS commented that OSHA underestimated the length of conveyors by 
using 100 linear feet in its estimate, and suggested that the estimate 
of 200 feet that it used as the basis for its estimates was still an 
underestimation for some foundries (Document ID 2307, Attachment 26, 
Control Basis and Control Changes tabs). URS maintained OSHA's estimate 
of $20.73 per linear foot in its own calculations. However, it appears 
that URS did not understand that OSHA estimated 100 linear feet of 
conveyors for every 4 workers, not 100 linear feet of conveyors for an 
entire affected establishment. Further, the URS comment indicated that 
100 linear feet was an underestimate for ``medium and large 
foundries.'' But because OSHA's estimate of 100 linear feet is for 
every four workers, OSHA actually estimated much longer conveyor 
lengths for larger facilities with more workers. OSHA has determined 
that its estimate of 100 linear feet for every four workers at a cost 
of $20.73 per linear foot is a reasonable approach for estimating the 
costs of conveyor covers.
Selected Control Options That Are Not Costed
    Consistent with ERG's cost model, in the PEA OSHA chose not to 
estimate costs for some control options mentioned in the accompanying 
technological feasibility analysis in Chapter IV of the PEA. In these 
cases, OSHA judged that other control options for a specific at-risk 
occupation were sufficient to meet the PEL. AFS identified several 
control options for which OSHA did not estimate costs:

 Substitution of non-silica sand (V-A-51)
 Pneumatic sand handling systems (V-A-51)
 Didion drum to clean scrap for furnace operators (V-A-52)
 Non-silica cores and core coatings (V-A-52)
 Professional cleaning costs and associated downtime (V-A-52)
 Physical isolation of pouring areas (V-A-52)
 Modify ventilation system to reduce airflow from other areas 
(V-A-52)
 Automation of a knockout process (V-A-53)
 Automated abrasive blast pre-cleaning of castings for 
finishing operators (V-A-54)
 Wet methods (V-A-54)
 Low silica refractory (V-A-55) (Document ID 2379, p. 16)

    Just because a control is mentioned in the technological 
feasibility analysis does not mean that OSHA has determined that its 
use is required--only that it represents a technologically feasible 
method for controlling exposures. The Agency developed cost estimates 
based on the lowest cost combination of controls that allows employers 
to move from an uncontrolled situation to meeting the new PEL. OSHA did 
not include the costs for possible controls that were either more 
expensive or were not necessary to achieve the PEL. OSHA (2016) 
describes in detail which controls were considered necessary to achieve 
the PEL. OSHA continues in the FEA to exclude costs for these kinds of 
more expensive possible controls.
Railroads
    In its preliminary estimates, OSHA inadvertently applied the 
preceding general industry PEL of 100 [mu]g/m\3\ in its analysis of the 
railroad industry. Silica exposures among railroad employees, however, 
result from ballast dumping, which is track work that is generally 
subject to OSHA's construction standard and covered by the preceding 
construction PEL of 250 [mu]g/m\3\ (see discussion of railroads in 
Chapter III, Industry Profile). As a result, OSHA has changed its 
conclusion that there would be no incremental costs for railroads to 
meet the new PEL. OSHA has reassigned all costs previously assigned to 
meeting the preceding PEL to being incremental costs of meeting the new 
PEL. Although the railroad activities affected by the new silica rule 
will typically constitute construction work, OSHA has categorized all 
compliance costs for railroads with general industry costs under NAICS 
482110 because the railroad industry is predominantly engaged in non-
construction work and its NAICS code is not typically classified as a 
construction code.
Costs of Engineering Controls for Hydraulic Fracturing in the PEA
    Both in the PEA and in the FEA, OSHA presented the methods of 
estimating the costs of controlling silica exposures during hydraulic 
fracturing separately from the engineering control costs for all other 
portions of general industry because there are some fundamental 
differences in the methodology OSHA used, and thus in the comments OSHA 
received on that methodology. In the PEA, OSHA began its analysis of 
hydraulic fracturing in the standard way of examining the set of 
engineering controls available to control employee exposures to silica. 
Unlike the way OSHA handled the rest of general industry, however, for 
hydraulic fracturing OSHA identified precisely which controls were 
necessary to go from current levels of exposure to the preceding 
general industry PEL of 100 [mu]g/m\3\ and then what further

[[Page 16483]]

controls would be necessary to go from the preceding general industry 
PEL of 100 [mu]g/m\3\ to the new PEL of 50 [mu]g/m\3\. OSHA took a 
different approach for this sector because the data available for this 
industry, as a result of an extensive set of site visits, were adequate 
to make this type of determination. OSHA determined that a combination 
of wet methods, partial enclosure, and LEV controls would be sufficient 
to meet a PEL of 100 [mu]g/m\3\ for hydraulic fracturing. OSHA then 
determined that LEV controls at thief hatches and operator enclosures 
would be sufficient to reduce exposures during hydraulic fracturing 
from 100 [mu]g/m\3\ to 50 [mu]g/m\3\. The costs of these additional 
engineering controls were shown in Tables A-14, A-15, and A-16 for 
large, medium, and small fleets, respectively, in the PEA (the full 
derivation of the results in these tables can be found in ERG, 2013, 
Document ID 1712).
    As discussed in the Industry Profile section of the FEA (Chapter 
III), the basic unit for analysis for this industry is the fleet rather 
than the establishment. Rather than allocating costs according to the 
proportion of workers above a given exposure level, as was done for the 
rest of general industry, for hydraulic fracturing the controls applied 
per fleet were judged to reduce the exposures of all workers associated 
with the fleet.
Public Comments on OSHA's Preliminary Cost Estimates for Engineering 
Controls in Hydraulic Fracturing
General Methodology
    Though there were extensive comments on OSHA's estimates of 
engineering control costs for hydraulic fracturing, no commenter 
objected to the differences in methodology compared to OSHA's treatment 
of the other general industry sectors (as outlined above). Halliburton 
Energy Services, Inc. commented that OSHA's analysis ``lacks data'' 
(Document ID 4211, p. 5). As discussed in Chapter IV Technological 
Feasibility, OSHA agrees that there is limited experience with many 
possible controls. For this reason, OSHA has allowed this industry an 
extended compliance deadline of five years before they have to meet the 
new PEL with engineering controls. However, OSHA does not agree that 
this adds significant uncertainty to the costs analysis. The costs of 
the controls OSHA has examined, and especially those needed to go from 
the preceding general industry PEL to the new PEL can readily be 
ascertained. It is possible that the cost of some controls that have 
not yet been tested and that OSHA has not costed could be much lower 
than the costs OSHA estimated in the PEA and in the FEA.
Compliance Rate
    In the joint comments submitted by the American Petroleum Institute 
and the Independent Petroleum Association of America (API/IPAA or ``the 
Associations''), the Associations disagreed with OSHA's estimated 
current compliance rate for the use of engineering controls. In the 
PEA, OSHA estimated a compliance rate of ten percent for engineering 
controls in this industry. In their comments the Associations said that 
``ERG assumed that 10% of all hydraulic fracturing firms already 
utilize: (1) Baghouse controls; (2) caps on fill ports; (3) dust 
curtains; (4) wetting methods; and (5) conveyor skirting systems'' 
(Document ID 2301, p. 40, fn. 148).
    While OSHA used a compliance rate of ten percent for all of these 
controls, it is not meant to represent that all prescribed controls are 
used in ten percent of firms. OSHA's compliance rates take into account 
that some well sites, as documented in Chapter IV of the FEA, were 
observed to be using a variety of controls that reduce dust levels, and 
as a result, those firms will not need to implement as many additional 
controls in order to achieve the new PEL. Further, as noted in Chapter 
IV of the FEA, the industry is constantly installing additional 
controls to reduce silica exposures. Thus the Agency sees no reason to 
change its estimate of current compliance. In any case, removing the 
assumption would make only a ten percent difference to the cost 
estimates, which would not be a change of large enough magnitude to 
threaten OSHA's conclusion that compliance with the final rule is 
economically feasible for the hydraulic fracturing industry.
Maintenance Costs
    In the PEA, OSHA estimated that the life of most capital equipment 
would be ten years, and that maintenance and operating costs would 
range from ten to thirty percent of capital costs per year (ten percent 
being most common).
    API/IPAA argued that the hostile, sandy environment of the well 
site shortens the useful life of equipment and increases maintenance 
costs. The Associations estimated that the useful life of equipment 
ranges from 5 years to 7.5 years and that annual operating and 
maintenance costs range from 10 percent to 25 percent of capital costs. 
While OSHA agrees that the oilfield environment is challenging and 
dusty, there is no evidence in the record that these environments are 
more challenging than other industrial settings where equipment lives 
of 10 years and operating and maintenance costs of 10 to 30 percent 
have been used as reasonable estimates.
Cost of Specific Controls
Dust Booths
    In the PEA, OSHA estimated that there would need to be one dust 
booth for each sand moving machine, and that this would result in one 
dust booth for small fleets, three for medium fleets, and five for 
large fleets. In critiquing OSHA's cost analysis for hydraulic 
fracturing, API/IPAA disagreed with OSHA's estimates that only sand 
mover operators would need to utilize dust control booths in order to 
achieve the new PEL (Document ID 2301, p. 69). API/IPAA suggested that 
instead there would need to be one booth per affected worker and that 
only one worker could utilize a given booth. In the Associations' 
estimate this would mean that there would need to be 3, 8 and 12 booths 
for small, medium, and large fleets, respectively (Document ID 2301, 
Attachment 4, Dust Booths, row 9).
    As discussed in the technological feasibility chapter of the FEA, 
OSHA agrees that workers other than sand mover operators will need to 
use dust booths. However, OSHA does not agree that a booth can only 
accommodate a single person. These booths are places of refuge and are 
not assigned to specific individuals. The technological feasibility 
chapter in the FEA determined that dust booths can accommodate more 
than one person per booth. Because OSHA agrees that more employees than 
sand mover operators will need booths, OSHA has raised its estimates of 
booths needed by size class from 1, 4, and 5 booths to 3, 6, and 8 
booths. While this estimate of the number of booths is lower than that 
recommended by API/IPAA, OSHA finds that these booths can accommodate 2 
persons per booth and thus can accommodate more workers than API/IPAA 
suggested.
    In the PEA, OSHA estimated the transportation costs for booths as 
$37.25 per booth. API/IPAA disagreed. The Associations argued that a 
cost of $513 for a small fleet, which would only have one booth, would 
be more appropriate (Document ID 2301, p. 69). Most of the difference 
between API/IPAA's cost estimate for deploying dust control booths and 
OSHA's estimate is attributable to the fact that the Associations 
presented their cost per fleet and OSHA presented its cost per

[[Page 16484]]

booth. API/IPAA applied their estimate of the number of booths 
necessary at these worksites when deriving their estimate and they 
estimated about six times as many booths being necessary as OSHA did. 
However, after further examination of this cost, OSHA determined that 
the standard per-mile shipping rate that it used to estimate 
transportation costs in the PEA was applied incorrectly. This resulted 
in an estimate of transportation costs for booths in the PEA that was 
too low. OSHA has determined that the cost to transport dust booths 
presented by the Associations more completely captured the costs 
associated with transporting these booths. For the FEA, OSHA has 
accepted the Associations' per-fleet transportation cost of $513 for 
each booth and applied the cost to the Agency's estimate of the number 
of booths necessary to control silica exposures on well sites.
Water Misting
    In the PEA, OSHA estimated that water misting system would be 
needed to control residual emissions from some releases from sand 
moving systems. These water misting systems were estimated to cost 
$60,000 per fleet to purchase and an additional 20 percent of the 
purchase cost for installation. API/IPAA incorrectly assumed that these 
water misting systems were intended to control all dust emission from 
truck traffic and other sources (Document ID 2301, pp. 69-70). This was 
not the case--dust suppression for truck and other traffic was costed 
at a much higher rate separately from water misting.
    OSHA's cost estimates for misting systems were based on 
conversations with a mining dust control specialist who indicated the 
price and efficacy of available water misting systems (Document ID 
1571). While API/IPAA disagreed with OSHA's costs, they did not offer 
any data to show an alternative cost, instead simply carrying OSHA's 
estimate for water misting systems forward in their analysis to arrive 
at their cost estimate (Document ID 2301, Attachment 3, Water Misting, 
cells K:O6 and J8). OSHA has determined that the equipment that formed 
the basis for its cost estimates in the PEA may not be durable enough 
to stand up to the wear from frequent loading, unloading, and 
transportation. Therefore, the Agency, based on its own judgement, has 
increased the estimated cost of a water misting system by 33 percent in 
order to account for the need for a more durable system. Based on this, 
OSHA's final cost analysis for hydraulic fracturing includes costs of 
$79,800 per fleet to purchase the equipment plus installation costs of 
$15,960 for installation (20 percent of the purchase price) for water 
misting equipment to control residual dust emissions from sand moving 
systems.
Costs of Transportation
    In developing the costs for hydraulic fracturing firms to comply 
with this rule in the PEA, it was determined that the baghouse controls 
that are commercially available are integrated into sandmover units and 
therefore should not present any logistical difficulties for 
transportation purposes. However, in examining the costs to transport, 
assemble, and disassemble the control equipment, API/IPAA noted 
potential difficulties in adding baghouse controls to sandmovers, which 
are often nearly at weight limits for road movement (Document ID 2301, 
p. 71).
    OSHA's determination about integrated units has not changed since 
the PEA. The existence of integrated units is further discussed in 
Chapter IV of the FEA, Technological Feasibility. OSHA notes that 
sandmover units are not the heaviest items transported by hydraulic 
fracturing firms, so the additional weight associated with baghouse 
controls would be insignificant in this context. These firms are highly 
experienced in moving the heavy, bulky equipment needed on well sites 
and including additional controls on this equipment is not expected to 
create a situation that exceeds the capabilities of these firms.
Containerized Systems
    Commenting on OSHA's analysis of the cost of controls for hydraulic 
fracturing, API/IPAA expressed concern that OSHA was considering 
requiring the use of containerized systems. The Associations stated 
that these systems would be economically infeasible for small fleets 
and raised questions about whether these systems would be sufficient to 
allow fleets using them to achieve the PEL (Document ID 4222, p. 7). 
Neither in the PEA nor the FEA has OSHA's cost analysis reflected the 
use of containerized systems, nor does OSHA require their use. Instead, 
containerized systems represent a possible technological change that 
could potentially reduce the costs of silica control. OSHA has in no 
way quantitatively tried to estimate the effects of this possible 
reduction.
Conveyor Skirting
    In the PEA, OSHA found that conveyor skirting systems with 
appropriate LEV would be needed to meet the new PEL, and included the 
cost of such controls in the incremental costs associated with the new 
PEL. As discussed in Chapter IV, Technological Feasibility, in the FEA, 
however, OSHA now finds that these conveyor skirting systems will be 
needed to meet the preceding PEL, but not to further lower exposures to 
the new PEL, so OSHA is not including costs for these controls as 
incremental costs associated with achieving the new PEL. As a result, 
the FEA does not include costs for conveyor skirting systems and LEV.
Dust Suppression--Control of Dust Generated From Traffic
    On the other hand, dust suppression to control silica emissions 
generated by truck traffic, estimated in the PEA as necessary only to 
meet the preceding PEL, has now been determined to be necessary to meet 
the new PEL (see Chapter IV, Technological Feasibility in the FEA). As 
a result, in the FEA OSHA added the costs of dust suppression to 
control silica dust generated by truck traffic to the estimated 
incremental costs of meeting the new PEL. OSHA estimates that dust 
suppression is more expensive in the aggregate than conveyor skirting 
systems with appropriate LEV.
    OSHA made two additional changes to the costs of dust suppression 
from the PEA to the FEA. First, OSHA accepted the unit costs for dust 
suppression application provided by API/IPAA (Document ID 2301, 
Attachment 3, Dust Suppression). This unit cost is somewhat lower than 
the original estimate that OSHA adopted in the PEA (Document ID 1712). 
This seems reasonable to OSHA based on the costs of the most commonly 
used dust suppression materials. Second, OSHA has determined that these 
controls will be utilized to reduce exposures for ancillary support 
workers and remote/intermittent workers, 50 percent of whom work in 
situations that currently have exposures below the new PEL (as shown in 
the exposure profile in the section on hydraulic fracturing in Chapter 
IV, of the FEA, technological feasibility). As a result, instead of 
assigning dust suppression costs for all wells (as in the PEA), OSHA 
determined in the FEA that dust suppression costs would be incurred by 
50 percent of wells. This aligns with a view that, in many cases, 
natural conditions (silica content of soils, dustiness, wetness and/or 
climate) are such that dust suppression is not needed.

[[Page 16485]]

Small Business Considerations
Small Business Regulatory Enforcement Fairness Act (SBREFA) Comments on 
Compliance
Costs in General Industry and Maritime
    Before publishing the NPRM, OSHA received comment on the accuracy 
of its unit costs through the Small Business Advocacy Review (SBAR) 
Panel process.
    The Small Entity Representatives (SERs) who participated in the 
2003 SBAR Panel process on OSHA's draft standards for silica provided 
many comments on the estimated compliance costs OSHA presented in the 
Preliminary Initial Regulatory Flexibility Analysis (PIRFA) for general 
industry and maritime (Document ID 0938).
    In response to the SERs' comments, OSHA carefully reviewed its cost 
estimates and evaluated the alternative estimates and methodologies 
suggested by the SERs. OSHA updated all unit costs presented in the 
PIRFA to reflect the most recent cost data available and inflated all 
costs to 2009 dollars prior to publication of the proposed rule. 
However, the Agency generally determined that the control cost 
estimates in the PIRFA were based on sound methods and reliable data 
sources.
    For the PEA, OSHA reviewed the SERs' cost estimates for small 
entities in the foundry and structural clay industries. Given that 
those SERs did not report their own sizes, the Agency could not compare 
their estimates to the estimates in the PEA. OSHA concluded that the 
compliance costs reported by the SERs in general industry that did 
provide size data were not incompatible with OSHA's own estimates of 
the costs of engineering controls to comply with the PEL. As discussed 
above, for the FEA, OSHA has halved the number of workers assumed to be 
covered by each control for most controls in establishments with fewer 
than twenty employees, which results in a doubling of the engineering 
control costs for these establishments.
Comments and Responses on Costs for Small Establishments
    Stuart Sessions, testifying on behalf of ACC, argued that OSHA had 
underestimated costs to small establishments for two reasons: (1) Small 
establishments may have higher exposures and therefore many need to 
spend more money installing controls to reduce those exposures; and (2) 
costs to small establishments may involve diseconomies of scale--
whereby smaller facilities would have to pay more per unit to procure 
and install systems--that OSHA had not accounted for (Document ID 4231, 
Attachment 1, pp. 2-4).
    With respect to the issue about small establishments having higher 
exposures--the commenter simply asserted that this is the case without 
providing any evidence to support the claim. Mr. Sessions speculated 
that smaller businesses have a ``lesser ability to afford compliance 
expenditures and lesser ability to devote management attention to 
compliance responsibilities'' (Document ID 4231, Attachment 1, p. 2). 
While it is possible that very small establishments may not have the 
same controls already in place as large establishments, as asserted by 
the commenter, this does not necessarily mean that very small 
establishments will have higher exposures. Small and very small 
establishments typically only have one shift per day, so fewer shifts 
are being worked where there is a potential for exposure. They also may 
spend more time on activities not involving silica exposures. For 
example, a small art foundry that produces one or two castings a week 
will simply spend proportionally less time on activities that lead to 
silica exposure than a large production foundry.
    With respect to the issue of diseconomies of scale, OSHA has taken 
this phenomenon into account in its cost estimates in the FEA. First, 
in order to provide a conservative estimate of costs for the purposes 
of determining the impacts on very small employers, OSHA has revised 
what Mr. Sessions called ``the most inappropriate of OSHA's 
assumptions'' (Document ID 4231, Attachment 1, p. 6). In the PEA, OSHA 
estimated that a single control would reduce the exposures of four 
workers. For the FEA, OSHA has revised its estimates so that the number 
of workers whose exposures are reduced by a control are half that used 
in the PEA for establishments with fewer than 20 employees--reducing 
the number of workers covered by a control from four to two. OSHA made 
this adjustment even though there are ways in which small 
establishments may have lower costs per cfm than larger establishments. 
For capital costs, a major element of cost per cfm is the length of 
ductwork. Within the same industry, the length of ductwork will be much 
shorter in smaller establishments. For operating costs per cfm, length 
of operating time is a key element of costs.
    OSHA has continued to estimate that the exposures of four employees 
whose exposures would be reduced per control for establishments with 
more than twenty employees (even though it is likely that more than 
four workers have their exposures reduced per control in the largest 
establishments). This effectively means that very large establishments 
with hundreds of employees have been modeled as if their costs were 
equivalent to that of several 20-40 person establishments combined. Far 
from neglecting diseconomies of scale, in an effort to be conservative 
and adequately account for the challenges faced by smaller 
establishments, OSHA has instead neglected to account for economies of 
scale in larger establishments.
    Mr. Sessions calculated some higher overall costs for smaller 
establishments (Document ID 4231, Attachment 1, pp. 6-10). However, 
these costs are critically dependent on the assumptions already 
addressed and rejected by OSHA, such as that exposures are random and 
that any exposures require that all possible controls be installed to 
control those exposures.
Final Control Costs
Unit Control Costs
Methodology
    For the FEA, OSHA used unit costs developed in the PEA for specific 
respirable crystalline silica control measures from product and 
technical literature, equipment vendors, industrial engineers, 
industrial hygienists, and other sources, as relevant to each item. 
Some PEA estimates were modified for the FEA based on comments in the 
record, and all costs were updated to 2012 dollars. Specific sources 
for each estimate are presented with the cost estimates. Wherever 
possible, objective cost estimates from recognized technical sources 
were used. Table V-4 in the FEA provides details on control 
specifications and data sources underlying OSHA's unit cost estimates.
Summary of Control Costs for General Industry and Maritime
    Table V-5 in the FEA summarizes the estimated number of at-risk 
workers and the annualized silica control costs for each application 
group. Control costs in general industry and maritime for firms to 
achieve the PEL of 50 [mu]g/m\3\ level are expected to total $238.1 
million annually. As shown, application group-level costs exceed $15.0 
million annually for concrete products, hydraulic fracturing, iron 
foundries, railroads, and structural clay.
    Table V-6 in the FEA shows aggregate annual control costs in 
general industry and maritime by NAICS industry. These costs reflect 
the disaggregation of

[[Page 16486]]

application group costs among the industries that comprise each group 
(see Table III-1 in Chapter III of the FEA on the profile of affected 
industries.)
b. Control Costs in Construction
    In both the PEA and the FEA, OSHA determined that employers, in 
order to minimize exposure monitoring costs, would select appropriate 
controls from Table 1. The final estimate for control costs, however, 
includes Table 1 control costs for a larger number of employees than in 
the PEA. For the purpose of estimating control costs in the PEA, OSHA 
examined all of the employers with employees engaged in Table 1 tasks 
but judged that only a subset of those employers (those with workers 
exposed above the proposed silica PEL) would require additional 
engineering controls. For this final rule, OSHA has judged, for costing 
purposes, that all of the construction employers with employees 
performing any task covered in Table 1 will adopt the engineering 
controls for that task as specified in Table 1. Thus, in the FEA, OSHA 
took the more conservative approach--which may result in an 
overestimate of costs--of identifying the cost of controls for all 
employers with employees engaged in Table 1 tasks, not just the subset 
of employers with employees exposed above the PEL. However, as 
discussed in Chapter III of the FEA, OSHA did adjust control costs to 
reflect the 44 percent of workers in construction currently exposed at 
or below the PEL who are estimated to be in baseline compliance with 
the Table 1 requirements.
    OSHA is also likely overestimating the cost of controls for another 
reason. If the employer is able to demonstrate by objective data, or 
other appropriate means, that worker exposures would be below the 
action level under any foreseeable conditions, the employer would be 
excluded from the scope of the final rule. These employers would not 
require additional controls. OSHA did not have sufficient data to 
identify this group of employers and did not try to reduce the costs to 
reflect this group, so OSHA's estimate of costs is therefore 
overestimated by an amount equal to the costs for those employers 
engaged in covered construction tasks but excluded from the scope of 
the rule.
    A few tasks involving potentially hazardous levels of silica 
exposure are not covered in Table 1. Employers would have to engage in 
exposure monitoring for these tasks pursuant to paragraph (d) and use 
whatever feasible controls are necessary to meet the PEL specified in 
paragraph (d)(1). For example, tunnel boring and abrasive blasting are 
not covered by Table 1 and are therefore addressed separately in this 
cost analysis. Although several commenters identified various other 
activities that they believed were not covered by Table 1 that could 
result in crystalline silica exposure over the PEL (Document ID 2319, 
pp. 19-21; 2296, pp. 8-9), some of these activities were simply 
detailed particularized descriptions of included activities. For 
example, overhead drilling is addressed in the FEA, Chapter IV-5.4 Hole 
Drillers Using Handheld or Stand-Mounted Drills, and the demolition of 
concrete and masonry structures is addressed in the FEA, Chapter IV-5.3 
Heavy Equipment Operators. For the remainder, the available exposure 
data did not indicate that these activities resulted in a serious risk 
of exposure to respirable crystalline silica (see FEA, Chapter III 
Industry Profile, Construction, Public Comments on the Preliminary 
Profile of Construction and Summary and Explanation, Scope and 
Application); furthermore, these other activities could be addressed 
using the controls identified in the FEA. Because OSHA did not have 
sufficient data to identify a significant number of silica exposures 
above the PEL of 50 [mu]g/m\3\ for these activities, the Agency did not 
include costs for controlling silica exposures during these activities. 
Nevertheless, to the extent that employers find it necessary to 
implement controls for any activity that OSHA did not explicitly 
include in this analysis, the FEA shows that those controls are clearly 
economically feasible.
    The control costs for the construction standard are therefore based 
almost entirely on the tasks and controls specified in Table 1. Most of 
the remainder of this section is devoted to explaining the manner in 
which OSHA estimated the costs of applying appropriate engineering 
controls to construction activities as required by Table 1 of the final 
standard. These costs are generated by the application of known dust-
reducing technology, such as the application of wet methods or 
ventilation systems, as detailed in the technological feasibility 
analysis in Chapter IV of the FEA. These costs are discussed first, 
and, following that, the control costs for tasks not specified in Table 
1 are separately estimated.
    OSHA revised Table 1 between the PEA and the FEA. The entries 
included in the table have been modified with some tasks being added 
and some being removed.\35 \In addition, the methods of controlling 
exposures that Table 1 requires for certain tasks have changed in 
response to comments and additional analysis. Excluding changes to 
respirator requirements, which are addressed elsewhere in this 
preamble, significant and substantive revisions to Table 1 that have 
the potential to impact control costs include:
---------------------------------------------------------------------------

    \35\ Additionally, the nomenclature changed from ``Operation'' 
in the NPRM to ``Equipment/Task'' in the final rule.
---------------------------------------------------------------------------

     New entries on Table 1--
    [cir] Handheld power saws for cutting fiber-cement board (with 
blade diameter of 8 inches or less)
    [cir] Rig-mounted core saws and drills
    [cir] Dowel drilling rigs for concrete
    [cir] Small drivable milling machines (less than half-lane)
    [cir] Large drivable milling machines (half-lane and larger for 
cuts of any depth on asphalt only and for cuts of four inches in depth 
or less on any other substrate)
    [cir] Heavy equipment and utility vehicles used to abrade or 
fracture silica-containing materials (e.g., hoe-ramming, rock ripping) 
or used during demolition activities involving silica-containing 
materials.
    [cir] Heavy equipment and utility vehicles for tasks such as 
grading and excavating but not including: Demolishing, abrading, or 
fracturing silica-containing materials
     Removed entry for drywall finishing from Table 1
     Revised entries on Table 1--
    [cir] Drivable saw entry revised to permit outdoor use only.
    [cir] Portable walk-behind or drivable masonry saws divided into 
two entries--walk-behind saws and drivable saws.
    [cir] Handheld drills entry revised to include stand-mounted drills 
and overhead drilling.
    [cir] Combined entries for vehicle-mounted drilling rigs for rock 
and vehicle-mounted drilling rigs for concrete.
    [cir] Milling divided into three tasks--walk-behind milling 
machines and floor grinders; small drivable milling machines (less than 
half-lane); and large drivable milling machines (half-lane and larger 
with cuts of any depth on asphalt only and for cuts of four inches in 
depth or less on any other substrate).
    [cir] Heavy equipment used during earthmoving divided into two 
tasks--(1) heavy equipment and utility vehicles used to abrade or 
fracture silica-containing materials (e.g., hoe-ramming, rock ripping) 
or used during demolition activities involving silica-containing 
materials, and (2) use of heavy equipment and utility vehicles for 
tasks such as grading and excavating but not including: Demolishing, 
abrading, or fracturing silica-containing materials.

[[Page 16487]]

    [cir] Revised crushing machines entry to require equipment designed 
to deliver water spray or mist for dust suppression and a ventilated 
booth or remote control station.
    In addition to the new and revised tasks in Table 1, some of the 
controls and specifications required by Table 1 were revised for this 
final rule, including removal of ``Notes/Additional Specifications'' 
from individual Table 1 entries and addition of substantive paragraphs 
after the table. Those revisions include:
     Revised or newly required controls/specifications for 
Table 1 tasks--
    [cir] Revised requirement to operate and maintain tools/machine/
equipment in accordance with manufacturer's instructions to minimize 
dust emissions.
    [cir] Revised specifications for dust collectors to require they 
provide at least 25 cubic feet per minute (cfm) of air flow per inch of 
blade/wheel diameter (for some, but not all entries that include a dust 
collection system as a control method).
    [cir] Revised specification for dust collectors to require they 
provide the air flow recommended by the tool manufacturer, or greater, 
and have a filter with 99 percent or greater efficiency and a filter-
cleaning mechanism (for some, but not all entries that include a dust 
collection system as a control method). The entries for handheld 
grinders for mortar removal (i.e., tuckpointing) and handheld grinders 
for uses other than mortar removal require a cyclonic pre-separator or 
filter-cleaning mechanism.
    [cir] Revised requirement for tasks indoors or in enclosed areas to 
provide a means of exhaust as needed to minimize the accumulation of 
visible airborne dust (paragraph (c)(2)(i)).
    [cir] Added requirement for wet methods to apply water at flow 
rates sufficient to minimize release of visible dust (paragraph 
(c)(2)(ii)).
    [cir] Revised specifications for enclosed cabs to require that 
cabs: (1) Are maintained as free as practicable from settled dust; (2) 
have door seals and closing mechanisms that work properly; (3) have 
gaskets and seals that are in good condition and working properly; (4) 
are under positive pressure maintained through continuous delivery of 
fresh air; (4) have intake air that is filtered through a filter that 
is 95% efficient in the 0.3-10.0 [mu]m range (e.g., MERV-16 or better); 
and (5) have heating and cooling capabilities (paragraph (c)(2)(iii)).
    [cir] Added requirement to operate handheld grinders outdoors only 
for uses other than mortar removal, unless certain additional controls 
are implemented.
    [cir] Added wet methods option for use of heavy equipment and 
utility vehicles for tasks such as grading and excavating but not 
including: Demolishing, abrading, or fracturing silica-containing 
materials.
    [cir] Added requirement to use wet methods when employees outside 
of the cab are engaged in tasks with heavy equipment used to abrade or 
fracture silica-containing materials (e.g., hoe-ramming, rock ripping) 
or used during demolition activities involving silica-containing 
materials.
     Removed controls/specifications for Table 1 tasks--
    [cir] Removed requirements to change water frequently to avoid silt 
build-up in water.
    [cir] Removed requirements to prevent wet slurry from accumulating 
and drying.
    [cir] Removed requirements to operate equipment such that no 
visible dust is emitted from the process.
    [cir] Removed local exhaust dust collection system option and 
requirement to ensure that saw blade is not excessively worn from the 
entry for handheld power saws.
    [cir] Removed requirement to eliminate blowing or dry sweeping 
drilling debris from working surface from the entry for handheld and 
stand-mounted drills (including impact and rotary hammer drills).
    [cir] Removed additional specifications for dust collection systems 
for vehicle-mounted drilling rigs for concrete (e.g., use smooth ducts 
and maintain duct transport velocity at 4,000 feet per minute; provide 
duct clean-out points; install pressure gauges across dust collection 
filters; activate LEV before drilling begins and deactivate after drill 
bit stops rotating).
    [cir] Removed requirements to operate grinder for tuckpointing 
flush against the working surface and to perform the work against the 
natural rotation of the blade.
    [cir] Removed dust collection system option and requirement to use 
an enclosed cab from crushing machines.
    These and other changes to Table 1 are discussed in detail in 
Section XV: Summary and Explanation of this preamble. While Table 1 has 
changed with regard to the tasks included and the control methods 
required, OSHA's methodology used to estimate the costs of controls for 
the construction industry has remained basically the same as that 
explained in detail in the PEA, with steps added (and explained in the 
following discussion) to address cost issues raised during the comment 
period and the updates and revisions to Table 1. OSHA summarizes the 
methodology in the following discussion, but the PEA includes 
additional details about the methodology not repeated in the FEA.
    OSHA adopted the control cost methodology developed by ERG (2007a, 
Document ID 1709) for the PEA and subsequently for the FEA. In order to 
provide some guidance on that cost methodology, OSHA itemizes below the 
three major steps, with sub-tasks, used to estimate control costs in 
construction, with two additional steps added for the FEA to estimate 
the number of affected workers by industry and equipment category \36\ 
(numbered Step 3) and to estimate control costs for self-employed 
persons (numbered Step 5)--tables referenced below are in Chapter V of 
the FEA:
---------------------------------------------------------------------------

    \36\ The term ``equipment category'' as used here matches the 
broad headings used in the Technological Feasibility analysis. Later 
on in this section, OSHA identifies which Table 1 tasks are included 
in each equipment category.
---------------------------------------------------------------------------

     Step 1: Baseline daily costs, relative costs of controls, 
and labor share of value
    [cir] Use RSMeans (2008, Document ID 1331) estimates to estimate 
the baseline daily cost for every representative job associated with 
each silica equipment category (Table V-30) and unit labor and 
equipment costs (Table V-31).
    [cir] Use vendors' equipment prices and RSMeans estimates to 
estimate the unit cost of silica controls (Table V-32), and estimate 
the productivity impact for every silica control and representative 
job, to be added to the cost of the control applied to a particular job 
(Table V-33).\37\
---------------------------------------------------------------------------

    \37\ This latter sub-step was performed in the PEA, but it was 
inadvertently omitted in the text summary.
---------------------------------------------------------------------------

    [cir] Use the costs from Tables V-32 and V-33 to calculate the 
incremental productivity impact, labor cost, and equipment cost for 
each representative job when controls are in place (Table V-34).
    [cir] Using Tables V-30 and V-34, calculate the percentage 
incremental cost of implementing silica controls for each 
representative job (Table V-35).
    [cir] Calculate the weighted average incremental cost (in 
percentage terms) and labor share of total costs for each silica job 
category (outdoors and indoors estimated separately) using the assumed 
distribution of associated representative jobs (Tables V-36a and V-
36b).
     Step 2: Total value of activities performed in all Table 1 
silica equipment categories
    [cir] Match BLS Occupational Employment Statistics OES

[[Page 16488]]

occupational classifications for key and secondary workers with the 
labor requirements for each equipment category (Table V-37) and 
estimate the full-time-equivalent (FTE) number of employees by key and 
secondary occupations working on each silica task (Tables V-38a and V-
38b).
    [cir] Based on the distribution of occupational employment by 
industry from OES, distribute the full-time-equivalent employment 
totals for each equipment category by NAICS construction industry 
(Table V-39).
     Step 3: Total affected employment by industry and 
equipment category
    [cir] Disaggregate construction industries into four distinct 
subsectors based on commonality of construction work (Table V-40a) and 
then estimate the percentage of affected workers by occupation, 
equipment category, and construction subsector (Table V-40b).
    [cir] Use the percentage of affected workers by occupation, 
equipment category, and construction subsector (Table V-40b) to obtain 
total affected employment by occupation (Table V-41) and total affected 
employment by industry and task (Table V-42).
     Step 4: Aggregate silica control costs (not including 
self-employed persons)
    [cir] Using the FTE employment totals for each task by NAICS 
construction industry (Table V-39) and the mean hourly wage data from 
OES, adjusted for fringe benefits, calculate the annual labor value of 
each Table 1 silica activity by NAICS construction industry (Table V-
43).
    [cir] Using the labor share of value calculated for each activity 
performed in a silica-related equipment category (Table V-43), estimate 
the total value of each Table 1 equipment/task category by industry 
(Table V-44).
    [cir] Estimate the distribution of silica work by equipment type, 
duration of activity, and location of activity (Table V-45).
    [cir] Multiply the total value of Table 1 construction activities 
requiring controls (Table V-44) by the percentage incremental cost 
associated with the controls required for each activity that uses 
equipment in each equipment category (Tables V-36a and V-36b) and 
weighted by the percentage of tasks performed outdoors and indoors/
within an enclosed space (Table V-45), to calculate the total control 
costs, adjusted for baseline compliance, by Table 1 equipment category 
and industry (Table V-46).
    [cir] Calculate engineering control costs for silica-generating 
construction activities not covered in Table 1 (Tables V-47a and V-
47b).
    [cir] Combine the control costs for Table 1 construction activities 
(Table V-46) and the control costs for construction activities not 
covered in Table 1 (Tables V-47a and V-47b) to calculate the total 
control costs by equipment category and construction industry (Table V-
48).
     Step 5: Adjust aggregate silica control costs to include 
self-employed persons
    [cir] Use data from the BLS Current Population Survey to estimate 
the ratio of the number of self-employed persons to the number of 
employees by occupation (Table V-49) and then redo the estimation after 
restricting self-employed persons to just those occupations covered by 
OSHA that potentially involve exposure to hazardous levels of 
respirable crystalline silica (Table V-50).
    [cir] Multiply the FTE rate for each occupation (from Tables V-38a 
and V-38b) by the number of self-employed workers and employees in that 
occupation (from Table V-50) to obtain the ratio of FTE self-employed 
persons to FTE employees and then reduce that ratio to reflect only 
self-employed persons working on a multi-employer worksite where the 
work of the self-employed person cannot be isolated in time or space 
(Table V-51).
    [cir] Increase the earlier estimate of control costs by equipment 
category and industry (Table V-48) by the adjusted FTE ratio of self-
employed workers (Table V-40) to calculate total control costs by 
equipment category and industry with self-employed persons included 
(Table V-52).
Baseline Costs of Representative Jobs
Baseline Job Safety Practices
    OSHA's cost estimates address the extent to which current 
construction practices incorporate silica dust control measures. Thus, 
OSHA's baseline reflects such safety measures as are currently 
employed. To the limited extent that silica dust control measures are 
already being employed, OSHA has reduced the estimates of the 
incremental costs of silica control measures to comply with the new 
PEL. As discussed in Chapter III of the FEA and summarized in Tables 
III-A-1 and III-A-2, OSHA estimates that 44 percent of workers with 
exposures currently below the new PEL are using the controls required 
in Table 1.
Representative Jobs
    Unlike the situation with the general industry/maritime standard, 
OSHA does not have extensive data identifying the number of employees 
engaged in Table 1 tasks or the duration of their exposure to 
respirable crystalline silica during those tasks. Therefore, ERG 
developed a model based on ``representative jobs'' for the purposes of 
identifying the control costs necessary to comply with Table 1. Using 
RSMeans Heavy Construction Cost Data (RSMeans, 2008, Document ID 1331), 
which is a data source frequently used in the construction industry to 
develop construction bids, ERG (2007a, Document ID 1709) defined 
representative jobs for each silica-generating activity described in 
the feasibility analysis. These activities and jobs are directly 
related to the silica-related construction activities described in the 
technological feasibility chapter of the FEA. ERG (2007a, Document ID 
1709) specified each job in terms of the type of work being performed 
(e.g., concrete demolition), the makeup of the crew necessary to do the 
work, and the requisite equipment. For example, for the impact drilling 
activity, ERG defined three representative jobs for various types of 
demolition work. For each job, ERG derived crew composition and 
equipment requirement data from the RSMeans (2008,Document ID 1331) 
guide and then calculated the per-day baseline cost from the labor 
rates, equipment charges, material costs, and overhead and profit 
markups presented in the cost estimating guide.
    Table V-30 of the FEA shows the specifications for each 
representative job and the associated daily labor, equipment, and 
material costs. Table V-31 of the FEA provides a summary of the labor 
rates and equipment charges used to estimate the daily cost of each 
representative construction job in Table V-30 of the FEA. Note that the 
data on hourly wages with overhead and profit in Table V-31 of the FEA, 
obtained from RSMeans (2008, Document ID 1331), are employed here to be 
consistent with other RSMeans cost parameters to estimate the baseline 
costs of representative jobs. The RSMeans estimates are published for 
the purpose of helping contractors formulate job bids, so ERG relied on 
that data as an indicator of the amount of labor and time that would be 
required for each of the representative jobs in the cost model 
developed for this analysis. These RSMeans estimates are later used 
only to determine two ratios: The labor share of the costs of 
representative construction jobs and the percentage increase in the 
cost of each representative job due to the addition of controls to 
comply with the final rule. Everywhere else in the cost chapter, when 
the actual wages were important to the calculations and are expressed 
as

[[Page 16489]]

fixed amounts and not just ratios, OSHA used 2012 BLS wage data, which 
include fringe benefits but not overhead and profit.
SBREFA Panel Comments on Cost Methodology for Construction
    Prior to the publication of the PEA, one SBREFA commenter 
criticized the methodology for estimating engineering control costs on 
the grounds that while RSMeans estimates were used to establish the 
marginal costs of new controls (as a percentage of baseline costs), 
average wage rates (including fringe benefits) from the BLS 
Occupational Employment Statistics Survey, 2000, were used to calculate 
the value of at-risk tasks without providing a justification for not 
using RSMeans wage data (Document ID 0968, p. 13). Since BLS wage rates 
are significantly lower than the RSMeans rates used by ERG in earlier 
parts of the analysis, the commenter argued that this would 
significantly lower the base to which the marginal cost factors are 
applied to estimate compliance costs (Id.). This SBREFA commenter 
further argued that the RSMeans estimates are likely to be on the high 
end of estimated wages because they only cover unionized labor and are 
therefore likely to lead to high estimates of impacts. The commenter 
then recommended that more appropriate indexed labor wage costs be 
computed and used consistently throughout the analysis (Document ID 
0968, p. 14).
    First, the commenter's concern is misplaced because the choice of 
the RSMeans estimates source does not skew the results in the manner 
suggested by the commenter; nor does it even have a significant impact 
on the cost analysis. The RSMeans estimates were used only to develop 
the ratio of costs for the representative jobs to the total labor cost 
and then to determine the incremental compliance costs as a percentage 
of the total and the share (percentage) of estimate value with controls 
accounted for by labor. Because the RSMeans estimates are organized by 
project cost to assist contractors in bid planning, that data set is 
the logical choice for this purpose over BLS data, which provides wage 
data but does not provide comparable costs for projects. Dividing 
project labor value by the labor share of project value yields an 
estimate of total project value.
    The absolute level of the RSMeans wage and equipment cost levels do 
not directly affect the resultant aggregate compliance costs. While 
lower wage rates would lower the baseline costs of the representative 
jobs, it does not follow that control costs as a percent of baseline 
costs would also be lower. In fact, if lower wage rates are combined 
with the same equipment costs, the equipment part of incremental 
control costs would be a higher percentage of total baseline costs. 
Only the labor share (percentage) of baseline costs, along with the 
incremental compliance costs as a percent of baseline costs, are taken 
from the analysis of representative costs and used in the subsequent 
estimation of aggregate costs. The absolute levels of the wage rates 
and equipment costs taken from RSMeans do not directly enter the 
aggregate cost analysis.
    Second, OSHA notes that the BLS wage data, on which the aggregate 
compliance costs are based, are obtained from a statistically valid, 
national survey of employment and compensation levels and are the best 
available data characterizing national averages of wages by detailed 
occupation. For some of the reasons the commenter noted, OSHA believes 
that the BLS wage estimate provides a more accurate reflection of 
average wages.
    Another set of SBREFA commenters criticized OSHA's cost estimation 
methodology, arguing that fundamental errors resulted in serious 
underestimates of the costs of engineering controls. The commenters 
asserted without any significant explanation that the task-by-task 
incremental cost estimates (shown in Table V-23 of the PIRFA, Document 
ID 1720, p. 749) should have been multiplied by two factors: (1) ``The 
ratio of the RSMeans labor rate to the BLS wage and benefits rate,'' 
and (2) the inverse of the ``percentage in key occupations working on 
task'' from Table V-26 (also in the PIRFA, Document ID 1720, p. 766). 
Under this approach, the commenters argued that ``the cost of PEL 
controls for brickmasons, blockmasons, cement masons and concrete 
finishers performing grinding and tuckpointing would be approximately 
seventy-two (72.0) times the ERG estimate, and . . . the cost of PEL 
controls for drywall finishing (at the 50 [mu]g/m\3\ PEL) would be 
approximately 7.2 times the ERG estimate'' (Document ID 0004).
    The rationalization for these calculations was not provided, and 
OSHA found these conclusions without merit. The incremental control 
costs shown in Table V-34 of the FEA were based on RSMeans estimates 
for labor and equipment costs. As shown in Table V-34, these cost 
estimates, after adjustments for productivity impacts, are used to 
calculate the percentage increase in baseline costs associated with 
each control. The RSMeans-based cost estimates shown in Table V-34 are 
also used to estimate the share of total baseline task/project costs 
accounted for by labor requirements. The averages of the percentage 
increase due to incremental control costs and the labor share 
(percentage) of total baseline costs are shown in Table V-37 of the 
FEA. These two percentages are used to extrapolate the aggregate 
control costs associated with each task. This extrapolation was based 
on (1) the full-time-equivalent employment in key and secondary 
occupations associated with each task, and (2) the value of the labor 
time as measured by the BLS occupational wage statistics, adjusted for 
fringe benefits.
    OSHA provided similar responses in the PEA and requested comment on 
its responses to the SBREFA comments, but received none (see PEA, p. V-
131).
    The same set of SBREFA commenters further argued that OSHA's 
analysis contained five more ``fundamental errors'' (Document ID 0004). 
First, the commenters asserted that OSHA's calculations understate the 
actual cost because they are based on old data (1999 or 2000 data from 
RSMeans rather than RSMeans 2003 data). OSHA used the most recent 
available data at the time the initial preliminary analysis was 
completed and subsequently updated those data for the PEA (and the FEA) 
using RSMeans estimates from 2008 (Document ID 1331). However, as noted 
previously, the RSMeans estimates do not directly determine the 
absolute level of aggregate compliance costs, but rather the labor 
share (percentage) of project costs and incremental compliance costs as 
a percentage of baseline costs. This aspect of the analysis received no 
further comment and has been retained for the FEA.
    Second, the commenters asserted that there is no information to 
``suggest much less substantiate the premise that the exposure 
monitoring data in Tables 3-1 and 3-2 [in the ERG (2007a) report, 
Document ID 1709)] (even if they were properly collected and analyzed) 
are in any way representative of current workplace exposures across the 
country'' (Document ID 0004). In response, OSHA points out that the 
profiles used to estimate the numbers of workers exposed in excess of 
each PEL option were, in fact, based on the extensively documented 
technological feasibility analysis with many of the data points in the 
exposure profiles being taken from the findings of OSHA inspections 
(and based on ERG, 2007a, Document ID 1709). OSHA is tasked with using 
the best available evidence to develop the analyses, and the data in 
the exposure profile represent the best available evidence on current 
workplace

[[Page 16490]]

exposures to respirable crystalline silica. More importantly, for 
estimating the cost of controls, Table 1 in the final rule is intended 
to be the default option for protecting workers performing covered 
tasks, regardless of actual exposure level. The FEA reflects this, 
while recognizing that a sizable minority of workers with exposures 
below the PEL have limited their exposures by using such controls 
currently.
    Third, the commenters claimed that there is ``is no information to 
suggest much less substantiate the premise that the exposure monitoring 
data in Tables 3-1 and 3-2 (even if they were representative of current 
workplace exposures) are in any way representative of the non-existent, 
theoretical jobs artificially created by the FTE [full-time equivalent] 
analysis so as to justify their use as the foundation for Table 4-12'' 
(Document ID 0004). However, OSHA notes that the representative jobs on 
which the cost analysis is based were designed to correspond directly 
to the tasks assessed in the technological feasibility analysis. 
Furthermore, Table 4-12 in ERG (2007a, Document ID 1709) was derived 
directly from Table 3-2 and is independent of the ``FTE analysis.''
    Fourth, the commenters argued that a more logical and appropriate 
methodology would assume that all FTEs were exposed above the PEL in 
the absence of controls, and the commenter could find ``no 
justification, and substantial support to the contrary, for an approach 
that artificially condenses actual exposures into far more highly 
concentrated exposures (by condensing all at-risk task hours into FTEs) 
and then [assumes] that, despite the impact of this change, the grab 
bag of exposure monitoring described in ERG Tables 3-1, 3-2 and 4-12 
represents these FTEs'' (Document ID 0004). The commenters asserted 
that the effect in ERG (2007a, Document ID 1709) of ``first multiplying 
total project costs by the FTE percentage (from Table 4-8) and then by 
the `Percentage of Workers Requiring Controls' from Table 4-12 (and 
then by the average `Total Incremental Costs as % of Baseline Costs' by 
job category from Table 4-7) results in an unjustified double 
discounting of exposed workers in the incremental cost calculation'' 
(Document ID 0004).
    OSHA disagrees. The Agency notes that ERG (2007a, Document ID 1709) 
used the exposure profiles from the industry profile to estimate the 
number of full-time equivalent workers that are exposed above the PEL. 
In other words, this exposure profile is applicable if all exposed 
workers worked full time only at the specified silica-generating tasks. 
The actual number exposed above the PEL is represented by the adjusted 
FTE numbers (see Table 4-22 in ERG, 2007a, Document ID 1709). The 
adjusted FTE estimate takes into account that most workers, 
irrespective of occupation, spend some time working on jobs where no 
silica contamination is present. The control costs (as opposed to some 
program costs) are independent of the number of workers associated with 
these worker-days. OSHA noted in the PEA that the thrust of the comment 
about ``double discounting'' was unclear, but the commenters did not 
respond with clarification. Nothing is ``discounted'' in the estimation 
of aggregate control costs.
    Finally, the SBREFA commenters argued that the ``application of the 
FTE analysis to the additional equipment costs is based on the wholly 
unfounded assumption, contrary to actual experience, that this 
additional equipment could be used with perfect efficiency (i.e., never 
idle) so that it is only at a particular site during the time the at-
risk tasks are being performed'' (Document ID 0004). In response, OSHA 
notes that its analysis does in fact assume some efficiency with 
respect to the use of additional equipment required for controls. 
However, many of the equipment costs are based on monthly equipment 
rental rates provided by RSMeans that already embody some degree of 
idleness over the course of a year (see ERG, 2007a, Table 4-3, Document 
ID 1709). In other cases, daily equipment costs were directly estimated 
based on equipment purchase costs, annualization factors, and assumed 
operating and maintenance costs.\38\ OSHA did receive further comment 
on the issue following the publication of the PEA (Document ID 4217, 
pp. 84-88), and, in response, the Agency developed prorated ownership 
costs (equivalent to twice the rental rates) for control equipment for 
tradespersons performing tasks involving short-term, intermittent 
silica work.
---------------------------------------------------------------------------

    \38\ These were originally translated to daily costs on the 
assumption of full-time usage (240 days per year). However, in 
response to this comment, this rate was adjusted downward, assuming 
instead that equipment would be used 150 days per year (30 weeks), 
on average; OSHA applied this downward adjustment to equipment usage 
in the PEA and the effect of this change in equipment usage was to 
increase the daily cost of control equipment.
---------------------------------------------------------------------------

Public Comment on Engineering Control Costs in Construction
    Having already incorporated comments from small business in the 
SBREFA panel process, the Agency produced revised estimates for the PEA 
in support of the proposed silica rule. In the PEA, OSHA requested 
comments from rulemaking participants on the Agency's preliminary 
estimate of control costs in construction. Below are comments 
representative of the prominent issues that raised concerns.
    The most broad-based critique of the construction cost analysis 
came from the Construction Industry Safety Coalition (CISC), and its 
consultant Environomics (Document IDs 2319, 2320, and 4217). Several of 
their arguments regarding underestimation of costs related to an 
undercount of the affected construction population (for example, they 
believed OSHA should have accounted for the cost to control silica 
exposures for plumbers). OSHA agrees in part that there were some 
occupations--plumbers, plumber helpers, electricians, electrician 
helpers, roofers, roofer helpers, terrazzo workers and finishers, and 
sheet metal workers--that likely have exposure and should be included 
in this analysis, as they do perform some activities covered by Table 
1. These are discussed in FEA Chapter III, Industry Profile.
Owning Versus Renting Engineering Controls in Construction
    OSHA also received comments regarding the availability of control 
equipment. In its post-hearing brief, CISC commented:

    In the Agency's cost analysis, it has also made the entirely 
impractical assumption that controls (e.g., wet methods, LEV) for 
the tools that construction workers use in performing tasks that 
generate respirable silica need to be available only during the 
exact duration while a dusty task is performed. The CISC estimates 
costs instead to provide control equipment on an ``always 
available'' basis to workers who engage in dusty tasks. Control 
equipment must be available whenever a worker may need to perform an 
at-risk task, and not for only the very limited duration when the 
at-risk task is actually being performed. Costs for the engineering 
controls required to meet the reduced PEL in the proposed rule will 
be far higher than OSHA estimates (Document ID 4217, p. 29).

    While OSHA agrees that CISC's argument has merit, during hearing 
testimony CISC's representative acknowledged that its estimates did not 
initially take into account the economic life of a control. This is 
reflected in the following conversation between CISC's Stuart Sessions 
and OSHA's Robert Stone:

    MR. STONE: So returning to the methodology for costing, you 
pretty much used our numbers and you used our, presumably, like you 
mentioned the dust shroud that has a one-year life and, therefore,

[[Page 16491]]

after one year, you take the cost again the second year, is that 
right? And the third year, and so on? Okay. I think this is perhaps 
a problem with the way you've done your analysis. We used basically 
FTEs, full-time equivalents. You're using three percent of the time 
let's say for plumbers, as an example, you're applying it to three 
crews, all right? At the end of one year, you're having them buy 
another dust shroud. And my view . . . they will have used nine 
percent of the economic life of the dust shroud. Now, you can argue 
I'd make an adjustment because we estimate 150-[day construction 
work-year] use of it, for full-time use. This would suggest, though, 
that after one year, you will have used one-sixth of the life of 
that dust shroud and an employer is not going to throw it out. It's 
still functional. He'll use it for the next five years. He'll use it 
for six years. Any views on that?
* * *
    MR. SESSIONS: Yes. That's a good point, and I hadn't thought 
about that.
    MR. STONE: Okay, thank you. A related point is actually the same 
issue. It would be operating in maintenance costs. You're--it's 
going to be one-sixth of our original estimate, but I don't think 
you've made that adjustment.
    MR. SESSIONS: Correct. (Document ID 3580, Tr. 1501-1502).
    After the hearing discussion, CISC revised its methodology, 
noting:
    After additional thought and discussion about this issue with 
several construction tradespeople, we . . . concluded that useful 
life is a function of both how often the tool and controls are used, 
but also how long they sit in the construction worker's truck and 
get bounced around going from job site to job site (even when they 
are not used), and how often they are taken out of the truck and 
returned to the truck (even when they are only set up then taken 
down at the job site but not actually used). Thus useful life will 
increase if a tool sits idle for some percentage of the time when it 
is available, but useful life will not increase to the same 
proportional extent as the decrease in usage. We assumed in the 
example in workbook Tab # X2B that using the tool and equipment 1/4 
as often will double its useful life (Document ID 4217, p 89).

    OSHA agrees with this updated methodology and has adopted CISC's 
approach--essentially assuming one-half of the usage life over which to 
amortize the purchased control equipment--for jobs that typically 
involve intermittent short-term exposure. The jobs for which the Agency 
assumed a half-life of the control equipment were: (1) Hole drillers 
using hand-held or stand-mounted drills--for electricians, plumbers, 
carpenters, and their helpers, and for sheet metal workers; and (2) 
handheld power saws for carpenters and their helpers. Note that OSHA's 
adoption of this updated approach resolves CISC's criticism that OSHA 
had not accounted for productivity decreases from controls not being 
available when the worker needs to use them for short-term or 
intermittent silica jobs.
    For all other construction jobs (i.e., those not itemized above 
involving intermittent short-term exposure), OSHA did not adopt CISC's 
approach but instead (as in the PEA) used the market-derived rental 
rate for control equipment without either doubling the rental rate to 
take into account ``down-time'' or requiring purchase of the control 
equipment. There are several reasons OSHA retained its PEA approach for 
these jobs in the final rule:
     In most cases, an employer's own/rent decision for control 
equipment will be determined by the own/rent decision for the 
construction equipment (including construction tools) to which the 
control equipment will be applied. If the employer rents/owns the 
construction equipment, the employer will rent/own the control 
equipment. The major exception would be if a particular piece of 
control equipment could be applied to many types of construction 
equipment. An example might be a dust collector. In that situation, the 
employer might find it economic to rent the construction equipment and 
own the control equipment. But, in that case, the purchased control 
equipment will not be sitting idle.
     Construction equipment is sufficiently expensive that 
employers, as a general matter, will not find it economically efficient 
to have it sitting idle. That is why employers so frequently rent 
construction equipment. Of course, employers that do only one type of 
construction job all year (or those that are sufficiently large that 
they work on that particular type of construction job all year) will 
find it economic to own the construction equipment--as well as the 
control equipment--but then the control equipment will not be sitting 
idle.
     In light of permit requirements and other job-planning 
requirements, in almost all cases, the employer will have advance 
knowledge of the details of the construction job (as opposed to, 
sometimes, repair work in general industry). This knowledge would 
include the construction equipment--and controls--required to perform 
the job. In fact, employers will often schedule construction jobs 
precisely to avoid having construction equipment sitting idle. In other 
words, the typical employer--and certainly the competent employer--
won't come to the job site unprepared, needing to leave the job site to 
obtain rental equipment or controls.
     The construction sector is a significant component of the 
U.S. economy. There is a large, competitive construction equipment/
control rental market in place to serve it. In most places, employers 
should be able to obtain needed construction equipment/controls in a 
timely manner under terms similar to those estimated here.
    For the aforementioned reasons, OSHA believes that the ownership-
versus-rental cost issue, except in the case of construction jobs that 
involve intermittent short-term exposure, is somewhat of a red herring. 
The difference in amortized cost should be negligible, given that 
employers will choose to own or rent based on whichever is the lower-
cost alternative. In fact, because rental costs are typically somewhat 
higher than amortized ownership costs, OSHA may have overestimated 
compliance costs for those employers who purchase control equipment.
Self-Employed Persons
    CISC, and its contractor Environomics, claimed in their comments 
that OSHA had omitted the costs of compliance by sole proprietors 
(typically self-employed persons) (Document ID 4217, p. 80). The 
inclusion of such costs and the circumstances under which they would 
arise are discussed in Chapter III of the FEA. In the FEA OSHA has 
accounted for costs associated with controlling employee exposures from 
sole proprietor activities. The actual self-employment data and the 
estimated effect on employer costs are presented at the end of this 
section on engineering control costs in construction.
Full Cost vs. Incremental Cost
    Prior to the PEA, a participant in the SBREFA process noted that 
while OSHA established the total incremental cost for each silica 
control method (summarized for the final rule in Table V-35 of the 
FEA), the cost estimates were based on the application of a single 
control method. The commenter argued that there may be cases where two 
or more control methods would have to be applied concurrently to meet 
the exposure limits (Document ID 0968, p. 14). In response, OSHA noted 
in the PEA that for each task, specified control options correspond to 
the control methods described in the technological feasibility analysis 
in Chapter IV (of the PEA). These methods reflected the choices laid 
out in Table 1 of the proposed rule; they were also presented in Table 
V-25 in the PEA along with OSHA's calculation of the weighted average 
proportion of project costs attributable to labor and the incremental

[[Page 16492]]

control costs as a percentage of baseline project cost.
    Throughout the comment period, CISC reiterated its pre-PEA 
objections to OSHA's methodology of estimating incremental costs 
instead of the ``full'' compliance costs, which CISC defined as 
including the costs for employers to meet their existing duty to comply 
with OSHA's old PEL (CISC claims employers of ``nearly 60,000 workers'' 
were not in compliance with OSHA's preceding standard and would have 
OSHA attribute the costs of compliance with the preceding standard to 
the costs of this rule) (Document ID 4217, p. 33):
    In our view, OSHA has made two errors in the approach it has taken:
     First, the ``full'' compliance costs for reducing worker 
exposures from their current levels to below the proposed new PEL are 
the conceptually correct costs to estimate when assessing economic 
feasibility, not the ``incremental'' costs for reducing exposures to 
below the proposed new PEL from a starting point assuming compliance 
with the current PEL. In practice, employers will face the full costs, 
not the lesser incremental costs, and the economic feasibility 
assessment should consider whether employers can afford these full 
costs, not the hypothetical and lower incremental costs.
     Second, OSHA has made a conceptual error in the Agency's 
methodology for estimating compliance costs * * * Insofar as OSHA omits 
all costs for [employees with exposures >250 [micro]g/m\3\]--failing to 
estimate the costs to reduce their exposures all the way down below 50 
[micro]g/m\3\ instead of only to below 250 [micro]g/m\3\--OSHA 
estimates costs that fall short of the incremental costs of the 
Proposed Standard that the Agency aims to estimate. (Document ID 4217, 
pp. 96-97)
    Both arguments are now largely moot because in the FEA almost all 
of the construction engineering control costs are based on compliance 
with Table 1 and encompass all employees engaged in the Table 1 tasks, 
regardless of their current level of exposure. OSHA has included the 
full incremental--and full total--costs for all employers in 
construction who have workers who are performing tasks listed on Table 
1, even those workers with exposures currently above 250 [micro]g/m\3\.
    CISC's arguments for the construction sector are now only relevant 
to the very few tasks not covered by Table 1, such as tunnel boring. 
OSHA therefore addresses CISC's arguments in the context of those few 
tasks.
    The first argument is that employers who are not in compliance with 
the preceding PEL of 250 [micro]g/m\3\ will have to incur costs to 
achieve that PEL in addition to the costs they will incur to reach the 
new PEL of 50 [micro]g/m\3\. As laid out in the PEA, OSHA rejects this 
position, as this is inappropriate for estimating economic feasibility 
among firms making a good faith effort to comply with the existing 
silica rule. Employers who had a legal obligation to comply with OSHA's 
preceding PEL but failed to do so are not excused from their previous 
obligation by the new rule; nor can the fulfillment of a pre-existing 
duty be fairly re-characterized as a new duty resulting from a new 
rule. But this issue is not limited to construction, and a more 
complete discussion is presented in the general industry engineering 
control cost section in the FEA.
    The second argument can be dismissed on similar grounds. CISC's 
argument appears to assume that employers will incur different costs 
for different controls necessary to reduce exposures from above 250 
[micro]g/m\3\ down to 250 [micro]g/m\3\, and from 250 [micro]g/m\3\ 
down to 50 [micro]g/m\3\. In many cases, however, the same controls 
needed to bring exposures below 250 [micro]g/m\3\ will also bring 
exposures to 50 [micro]g/m\3\ or below, so there would be no cost 
associated with the new rule. To the extent that separate controls are 
required to reduce exposures down from 250 [micro]g/m\3\ to 50 
[micro]g/m\3\, OSHA does account for the costs for those controls.
General Comments on Cost Methodology
    James Hardie Building Products commissioned Peter Soyka of Soyka & 
Company LLC to perform an evaluation of the PEA. While Mr. Soyka's 
comments cover many aspects of the analysis and overlap with those of 
other commenters, some were relatively unique.
    In one place, Mr. Soyka questions the entire method of analyzing 
jobs from the level of workers and their tasks. He expressed concern 
about both what he termed the failure to capture the cost to the 
establishment, as well as the need for workers to have controls 
available (Document ID 2322, Attachment G, p. 165). OSHA did not, 
however, ignore other costs for establishments. Elements of these costs 
are dealt with at the establishment level for some ancillary provisions 
of the standard, and are discussed later in this chapter. The second 
element, regarding the availability of controls for certain 
occupations, mirrors concerns raised by Environomics and CISC, and has 
been dealt with above.
    Elsewhere in his comments, Mr. Soyka states that ``OSHA should 
develop revised unit costs that consider the full array of elements 
that affect what a business charges its customers for a unit of time 
expended.'' Such unit costs,'' he submitted, ``would include direct 
labor, fringe benefits, overhead, SG&A, and a reasonable allowance for 
profit (e.g., the typical cost of capital found in a specific industry 
or overall)'' (Document ID 2322, Attachment G, p. 182). The approach 
put forward in the PEA and in the FEA incorporates fringe labor costs. 
OSHA has provided a sensitivity analysis of the effects of including 
other cost elements in the sensitivity analysis section of the FEA. As 
noted elsewhere, for the FEA the Agency recognizes that the labor 
productivity effect of adopting certain controls is accompanied by a 
loss of productivity in equipment under certain circumstances; that 
additional cost has been incorporated in the FEA. The National 
Association of Home Builders (NAHB) faulted the costing of engineering 
controls in the PEA on several grounds, including several very similar 
to those raised by Mr. Soyka and addressed earlier. NAHB also stated 
that OSHA has not considered the ``unique nature of construction, in 
that sites are not fixed in nature, and that equipment may need to be 
moved between several sites in a single day'' or the ``compliance costs 
for cleanup of the jobsites'' (Document ID 2296, p. 38). Both are 
addressed in the FEA as opportunity costs or housekeeping costs.
Other Aspects of Unit Costs
    Following publication of the NPRM, a representative of 
petrochemical employers, the American Fuel and Petrochemical 
Manufacturers, raised concerns about retrofitting and clean-up costs 
that it claimed were improperly omitted from OSHA's analysis of 
engineering controls in construction:

    OSHA claims ``[t]he estimated costs for the proposed silica 
standard rule include the additional costs necessary for employers 
to achieve full compliance.''[ ] Yet it fails to consider the 
additional costs of retrofitting existing equipment to comply with 
Table 1 in Section 1926.1053 (Table 1). In addition to acquiring new 
engineering controls not previously implemented, many employers will 
have to modify pre-existing equipment to come into compliance (e.g., 
outfitting the cab of a heavy equipment bulldozer with air 
conditioning and positive pressure). Table V-3, found in OSHA's 
complete PEA, begins to address these costs by enumerating the 
capital and operating costs for the engineering controls required by 
Table 1. But it does not account for the ancillary costs of

[[Page 16493]]

retrofitting those controls, including the cost of retrofitting the 
equipment itself as well as the lost time the facility may absorb in 
doing so.
    OSHA also fails to account for the clean-up costs associated 
with the natural by-products from Table 1's required engineering 
controls. For example, many of the engineering controls require the 
use of wet methods or water delivery systems. [ ] Employers will 
incur costs from removing (from the clean-up process itself and lost 
time) excess water to prevent ice or mold from developing. Yet these 
costs go unaccounted for in the PEA (Document ID 2350, pp. 6-7).

    In the FEA, the Agency does not include any specific cost for 
retrofitting equipment. The record indicates that almost universally 
employers either already have equipment with the required controls 
available for use (e.g., wet method for saw), or the equipment allows 
for the easy addition of a control (e.g., shroud for HVAC). 
Furthermore, most equipment is portable and/or handheld and is 
relatively inexpensive with a useful life of two years or less. As a 
result, it would simply not make economic sense to retrofit the 
equipment when it would be less expensive to replace it. In addition, 
most other types of relevant construction equipment--heavier and 
drivable--generally have a useful life of ten years or less; control-
ready equipment of this type has been on the market for years and is 
typically already in use. Thus, OSHA did not estimate any retrofitting 
costs. While some employers might still retain pieces of earth-moving 
equipment that do not have a cab that complies with Table 1, equipment 
with a cab is the industry standard for both purchase and rental. As 
discussed in this chapter in the context of productivity, the 
implication is that the market has shifted to heavy equipment with cabs 
even in the absence of a silica standard. In addition, in final Table 1 
OSHA has reduced the number of tasks that require equipment with 
enclosed cabs to just a single task: Heavy equipment and utility 
vehicles used to abrade or fracture silica-containing materials or used 
during demolition activities involving silica-containing materials. For 
the odd piece of old, cab-less heavy equipment which does not conform 
to the requirements of Table 1, individual employers have the choice of 
renting the required equipment to perform that single task, or simply 
using the cab-less equipment only on non-silica tasks (thereby ceding 
the one silica-abrading construction task to employers that have more 
up-to-date equipment). In short, the requirement to use a cab when 
performing Table 1 tasks is not a requirement to retrofit all existing 
equipment that might conceivably be used for a Table 1 task.
    Regarding the question of clean-up costs, the commenter treats the 
issue as if there were no clean-up costs associated with generating 
silica currently. As discussed in the Environmental Impact Analysis 
(Section XIV of this preamble) and in the discussion of productivity 
impacts later in this section, there was substantial comment to the 
record indicating that in many, if not most, situations, the controls 
associated with reducing silica exposure will lead to a net decrease in 
the amount of time required for cleanup after a job. While OSHA is not 
attempting to quantify any potential cost savings, the record likewise 
does not support attributing additional costs to cleanup.
Specific Industry/Equipment Category Cost Comments
Crushing Machines
    William Turley, executive director of the Construction & Demolition 
Recycling Association (CDRA), broadly described the impacts he 
anticipated for his industry.

    Recyclers who crush materials for reentry into the economic 
mainstream as aggregate products would appear to have to do all of 
the following:
     Purchase and install climate-controlled enclosures or 
cabs for all crusher operators;
     Install crusher baghouses for particulate emission 
reduction;
     Enclose conveyor belts--a measure unprecedented in our 
industry;
     Install effectively designed and maintained water 
spraying equipment;
     Impose full-shift use of respirators for all quality 
control hand pickers working on processing lines;
     Establish and implement emission testing protocols and 
procedures to ensure compliance with the PEL;
     Implement medical surveillance programs for all 
employees engaged in material crushing activities; and
     Achieve a ``no visible emissions'' standard, which 
frankly is both unattainable and utterly unreasonable.
    To the best of our knowledge, no recycler in the United States 
has a system even resembling the above. The cost of such systems 
will unquestionably threaten the economic viability of construction 
& demolition debris recyclers across the Country. It must also be 
pointed out that the industry has an exceptionally diverse 
composition of larger operators with higher economic margins and 
small operations with limited capabilities to capitalize the type of 
equipment called for in this rulemaking (Document ID 2220, pp. 2-3).

    The final silica rule does not require all the above steps. OSHA 
expects that crushing machines will be used for construction/demolition 
activities, as discussed in detail in the Summary and Explanation of 
the standard. As such, OSHA anticipates that employers engaged in the 
recycling operation would follow Table 1 and would not need to conduct 
exposure monitoring.
    For crushing machines, OSHA removed the ``no visible emissions'' 
requirement and the requirement for enclosed cabs, both of which had 
been in the proposed Table 1. Employers are now required to use a spray 
system and comply with manufacturer instructions. Also, there is no 
requirement to enclose conveyor belts or install crusher baghouses. 
Instead, employees must use a remote control station or ventilated 
booth that provides fresh, climate-controlled air to the operator. For 
the FEA, OSHA added the cost of a ventilated booth for the use of 
crushing machines in construction/demolition activities. Most crushing 
machines are already equipped with movable controls that will allow 
operation of the machine from inside the booth, so no additional 
equipment modifications will be required for most machines. Crushers 
available for purchase or rental are also typically equipped with a 
water spray system, so OSHA has not assessed any incremental cost for 
sprayers.
Homebuilding--Roofing
    The National Roofing Contractors Association (NRCA) objected to 
OSHA's preliminary cost estimates for controls used to limit silica 
exposure in roofing operations, claiming that OSHA's preliminary 
estimate of an average of $550 per year for firms that employ 20 
workers or fewer (covering the majority of roofing contractors) had 
significantly underestimated the cost of specialized saws that would be 
required for roofing equipment. In support of the argument that OSHA 
had underestimated costs, NRCA identified costs for retrofitting 
portable saws with integrated dust collection systems along with 
specialized vacuums equipped with HEPA filters (Document ID 2214 p. 4).
    The task of cutting most roofing materials would fall under 
``Handheld power saws (any blade diameter)'' in Table 1, and the final 
version of Table 1 does not allow for the dust collection methods 
described, so the majority of costs quoted by NAHB are not relevant. 
Instead, the final version of Table 1 requires that the employer use 
wet methods. Second, the estimate of $550 a year in costs to very small 
employers was an estimated average across all affected establishments 
with fewer than 20 employees, not just roofing operations in 
homebuilding. Questions of small business impact or economic

[[Page 16494]]

feasibility for the roofing industry are dealt with Chapter VI of the 
FEA.
    The comments submitted by consultant Peter Soyka on behalf of James 
Hardie Building Products (``Hardie'') presented a table of typical 
devices with engineering controls involved in fiber cement cutting and 
an un-sourced range of costs for the retail prices of those types of 
devices and their controls (Document ID 2322, p. 13).
    Hardie's inclusion of a table of retail prices for the purchase of 
equipment with controls suggests there may have been a misunderstanding 
of the nature of OSHA's cost methodology--it is not based on purchasing 
entirely new pieces of equipment, but making sure the equipment has the 
controls necessary to comply with Table 1. To the extent commenters 
submitted estimates addressing the latter question, OSHA has taken them 
into consideration in its final estimates.
Asphalt Milling
    Fann Contracting, Inc. acknowledged that the availability of 
equipment with built-in controls is rising. However, the commenter 
suggested that OSHA's preliminary assessment of the design 
specifications and costs for the engineering controls identified in 
Table 1 of the proposed rule had under-counted the amount of milling 
machines and other paving-related equipment that the commenter believed 
would still require additional retrofits to enclosed cabs (sealing 
cracks, adding air conditioning, upgrading to HEPA filters, etc.) to 
satisfy the requirements in Table 1 (Document ID 2116, pp. 6-7).
    Table 1 in the final rule does not require a cab for milling 
machines or any of the equipment identified by the commenter for paving 
purposes, so the commenter's concerns are not relevant. Table 1 only 
requires cabs for ``(xvii) Heavy equipment and utility vehicles used to 
abrade or fracture silica-containing materials (e.g., hoe-ramming, rock 
ripping) or used during demolition activities involving silica-
containing materials,'' and specifies it as an option for ``(ix) 
Vehicle-mounted drilling rigs for rock and concrete.'' Table 1 requires 
employers to use wet methods to control dust emissions from milling 
machines. These costs have been accounted for in the cost analysis.
Drywall Finishing
    A SBREFA commenter raised questions about the availability of 
silica-free joint compound for drywall finishing (Document ID 0004). In 
the PEA, OSHA relied on NIOSH studies showing that silica-free joint 
compounds had become readily available in recent years (see ERG, 2007a, 
Section 3.2) (Document ID 1709). The cost model for the PEA assumed 
that 20 percent of drywall finishing jobs would continue to use 
conventional joint compound. Based on additional information, OSHA has 
determined that all commercially available joint compounds have no, or 
very low amounts of, silica and do not pose a risk to workers from 
respirable crystalline silica (Document ID 2296, pp. 32, 36; 1335, p. 
iii) and has therefore not included drywall finishing in Table 1 or 
taken any costs for this task (see Section XV. Summary and Explanation 
of the Standards, Specified Exposure Control Methods for more 
information).
Number of Days Controls Are Used Annually
    Whether equipment, and the relevant controls, are rented or 
purchased, the effective annual cost of the equipment is based on the 
assumed number of days per year that it would be used. In the PEA, OSHA 
had estimated rental of the equipment for 150 days during each 365-day 
period. Based on comments received from industry representatives during 
the 2003 SBAR Panel process (Docket ID 0968), this estimate had been 
reduced from an average of 250 days in the Preliminary Initial 
Regulatory Flexibility Analysis (PIRFA). This reduced workday estimate 
presumably reflected winter weather slowdown in many parts of the 
country, as well as general weather conditions (such as rain) that can 
interfere with many construction processes, and resulted in \2/3\ 
higher daily rental rates for control equipment.
    However, Environomics, in developing its own cost estimates, 
assumed that control equipment would be used for 250 days a year, 
without an articulated rationale for departing from the estimate 
provided during the SBAR Panel process (Document ID 4023, Attachment 2, 
X2B-Hole Drilling Unit Costs, Cell P:Q44). More importantly, 
Environomics selectively and inconsistently applied 250 days only to 
the frequency of usage but not to the daily rate (which OSHA had based 
on 150 days of usage). To see why it is a problem to apply a different 
number of days to the same daily rate, consider a piece of control 
equipment, with a one-year life, known to cost $1,500. Using a 150-day 
construction work-year, OSHA would estimate a daily rate for the 
control equipment of $10 ($1,500/150 days in the construction work-
year). The annual cost for that control would be $1,500 ($10 multiplied 
by 150 days). Using the same example, Environomics would keep OSHA's 
daily rate of $10 (amortized over 150 days) but apply it to a 250-day 
calendar to arrive at an annual cost of $2,500--where the one-year cost 
of the equipment was known to be $1,500. In short, the selective 250-
day methodology Environomics used results in an overestimation of costs 
by 67 percent.
    Accordingly, OSHA has decided to retain the 150-day construction 
work year based on the best available evidence, and the Agency has 
consistently applied that work-year throughout the cost analysis 
developed in the FEA for construction. (General industry and maritime 
work is typically less affected by weather, so a separate work-year 
number of days is used for those calculations).
Unit Control Costs
    In developing the cost estimates in the FEA, OSHA defined silica 
dust control measures for each representative job (see ERG (2007a, 
Document ID 1709). Generally, these controls involve either a water-
spray approach (wet method) or a dust collection system to capture and 
suppress the release of respirable silica dust. Wet-method controls 
require a water source (e.g., tank) and hoses. The size of the tank 
varies with the nature of the job and ranges from a portable water tank 
(unspecified capacity) costing $15.50 a day to a 10,000 gallon water 
tank with an engine-driven discharge, costing $168.38 a day.\39\ 
Depending on the type of tool being used, dust collection methods 
entail vacuum equipment, including a vacuum unit and hoses, and either 
a dust shroud or an extractor. The capacity of the vacuum depends on 
the type and size of tool being used. Some equipment, such as concrete 
floor grinders, comes equipped with a dust collection system and a port 
for a vacuum hose. The estimates of control costs for those jobs using 
dust collection methods also include the cost for HEPA filters.
---------------------------------------------------------------------------

    \39\ See Chapter X in the FEA for a discussion on the 
environmental impacts resulting from the use of wet methods for 
controlling exposure to silica.
---------------------------------------------------------------------------

    The unit costs for most control equipment are based on price 
information collected from manufacturers and vendors. In some cases, 
control equipment costs were based on data from RSMeans (2008) on 
equipment rental charges (Document ID 1331). Table V-32 of the FEA 
shows the general unit control equipment costs and the assumptions that 
OSHA used to estimate the costs for specific types of jobs.
    For each job identified as needing engineering controls, OSHA 
estimated

[[Page 16495]]

the annual cost of the appropriate controls and translated this cost to 
a daily charge, based on an assumed use of 150 days per year (30 
weeks), as explained earlier. The only exceptions were engineering 
controls expected to be used for short-term, intermittent work. For 
these controls, consistent with the CISC methodology that OSHA adopted, 
carpenters and other occupational groups were estimated to purchase 
this control equipment, and for costing purposes, OSHA amortized the 
equipment over its ``half-life''--that is, over 75 days rather than 150 
days (effectively doubling the daily capital costs of the equipment). 
Accordingly, Table V-32 of the FEA shows separate daily cost estimates, 
for regular and for infrequent use, for a dust extraction kit and for a 
10-15 gallon vacuum with a HEPA filter.
Incremental Labor Costs and Productivity Impacts in Construction
    In addition to incremental equipment costs, OSHA estimated in the 
PEA the incremental labor costs generated by implementing silica dust 
controls. These labor costs were generated by: (1) The extra time 
needed for workers to set up the control equipment; (2) potential 
reductions in productivity stemming from use of the controls; (3) 
additional time to service vacuum dust control equipment; and (4) 
additional housekeeping time associated with or generated by the need 
to reduce exposures. All additional labor costs related to the use of 
controls were subsumed into a single additional labor productivity 
impact estimate for each of the representative job categories. Except 
where otherwise noted, the productivity impact described is negative, 
meaning that the addition of the control is expected to reduce 
productivity. To develop estimates of the labor productivity impacts of 
the dust control equipment that would be required as a result of the 
proposed standard, ERG interviewed equipment dealers, construction 
contractors, industry safety personnel, and researchers working on 
construction health topics.
    In part, because most silica dust controls are not yet the norm in 
construction, knowledge about the impact of dust controls on 
productivity was uneven and quite limited. More precisely, few 
individuals that ERG interviewed were in any position to compare 
productivity with and without controls and the literature on this topic 
appears deficient in this regard. Overall, telephone contacts produced 
a variety of opinions on labor productivity effects, but very few 
quantitative estimates. Of all the sources contacted, equipment rental 
agencies and construction firms estimated the largest (negative) 
productivity impacts. Some equipment vendors suggested that there are 
positive productivity effects from control equipment due to improved 
worker comfort (from the reduction in dust levels). Others suggested 
that the use of dust collection equipment reduces or eliminates the 
need to clean up dust after job completion. Comments to the record, 
discussed below, closely mirrored this preliminary information.
    The estimation of labor productivity effects is also complicated by 
the job- and site-specific factors that influence silica dust exposures 
and requirements for silica dust control. Potential exposures vary 
widely with hard-to-predict characteristics of some specific work tasks 
(e.g., characteristics of materials being drilled), environmental 
factors (e.g., wet or dry conditions, soil conditions, wind 
conditions), work locations (e.g., varying dust control and dust 
cleanup requirements for inside or outside jobs), and other factors. 
Generalizations about productivity impacts, therefore, are hampered by 
the range of silica dust control requirements and work circumstances.
    After considering the existing evidence OSHA concluded that labor 
productivity impacts are often likely to occur and accounted for them 
in the PEA analysis. In the PEA, depending on the general likelihood of 
productivity impacts for each activity, OSHA used a productivity impact 
ranging from zero to negative five percent of output. After considering 
the many comments advocating for both increasing and decreasing the 
productivity impact estimates, OSHA has concluded that the estimates in 
the PEA were approximately correct and has retained the PEA estimates 
for the FEA. The comments and factors influencing each selection are 
described in the following discussion.
SBREFA Panel Comments on Productivity Impacts
    In response to the SBREFA Panel, the Reform OSHA Coalition 
commented on the estimates of the impact of exposure control equipment 
on productivity during construction operations. This SBREFA commenter 
noted that the estimates of the productivity impact of using additional 
control measures were based on interviews with dealers, contractors, 
and researchers working on construction health topics and expressed its 
opinion that it was not clear how this ``purely qualitative analysis 
[was translated] into productivity [impact] rates . . . . '' (Document 
ID 0968, p. 14). The commenter indicated that engineering control 
compliance costs would be sensitive to the ultimate choice of 
productivity impact measures (Id.).
    OSHA responded to these comments in the PEA as part of the 
discussion of the basis for OSHA's productivity estimates. OSHA 
summarizes the responses to SBREFA comments here for the convenience of 
the reader. As described in the PEA, ERG's research revealed little 
substantive, quantitative evidence about the magnitude of the 
productivity impacts of the controls, and in some cases, the direction 
of the impacts (positive or negative) appeared to depend on the 
specific nature of the job. OSHA's estimates in the preliminary 
analysis reflected ERG's best professional judgment about the likely 
magnitude of these impacts. Some of the estimates may be conservative 
because under some scenarios for certain tasks the productivity impacts 
could be significantly smaller than those shown in Table V-23 of the 
PEA. In some scenarios the productivity impact may even be positive.
    The same commenter also expressed a concern that even though 
``silica is not now considered a hazardous waste,'' OSHA had not 
analyzed the impact of the proposed rule on disposal of ``[silica-
]contaminated'' wastes such as ``filters of dust control vacuums and 
contaminated water discharge'' (Document ID 0968, p. 28). The commenter 
asserted that disposal issues are ``acute on the construction site 
where a means to readily dispose of such material or water is not 
available'' (Id.). The comment was somewhat puzzling because the 
comment was premised on the fact that there is not currently any 
``hazardous'' classification for such waste that would trigger special 
disposal duties, and the commenter did not explain why any additional 
costs would be incurred beyond normal disposal practices. OSHA did not 
identify any new areas of cost in its Environmental Impacts analysis 
presented in the FEA, and finds no evidence that employers will be 
required to incur additional environmental costs as a result of this 
rule, other than some potential permit-modification notification costs 
addressed in the discussion of engineering control costs for general 
industry in the FEA. The incremental disposal costs resulting from dust 
collected in vacuums, discarded filters, and other sources in 
construction are therefore likely to be de minimis. An analysis of wet 
methods for dust controls suggests that in most cases the amount of 
slurry discharge is not

[[Page 16496]]

sufficient to cause a runoff to storm drains or surface water.\40\
---------------------------------------------------------------------------

    \40\ For a more detailed discussion of this issue, see Chapter X 
of the FEA.
---------------------------------------------------------------------------

Public Comment on Productivity Impacts in Construction
    OSHA invited comment on the productivity impacts--positive and 
negative--resulting from the introduction of controls to limit exposure 
to silica. In the discussion below, OSHA reviews comments supporting 
both negative productivity impacts and positive productivity impacts. 
The comments supporting negative productivity impacts include 
assertions that OSHA underestimated the negative productivity impact of 
complying with the silica rule, failed to include a productivity impact 
on equipment, and failed to include a fixed productivity impact. OSHA 
considered those comments before concluding that it will generally 
retain the approach it used in the PEA, with the exception of 
selectively adding additional costs for productivity impacts on 
equipment in response to a point raised by CISC. OSHA will also explain 
separately why it is not calculating any productivity impact for two 
specific activities: (1) Use of cabs for earthmoving equipment, and (2) 
drywall installation.
Public Comments Suggesting That OSHA Underestimated the Productivity 
Impacts Associated With Engineering Controls
    The Interlocking Concrete Pavement Institute reported that 
``converting from in-place paver cutting to wet cutting and/or vacuum 
systems could induce a 50 percent productivity penalty,'' but did not 
otherwise substantiate that claim beyond noting that it was a survey 
response from one of its members (Document ID 2246, Attachment 1, p. 
3).
    Mr. Soyka, in the comments prepared for Hardie, critiqued OSHA's 
estimates of the productivity impact on construction operations as 
``far too small'' and urged OSHA to adjust productivity-loss estimates 
based on empirical data ``if available'' (Document ID 2322, Appendix G, 
pp. 14-15 and 21-22). However, the commenter did not clearly identify 
any such empirical data in the comments. The only labor-based 
engineering control cost alternative offered by the commenter that 
resembled ``empirical data'' is the addition of a seven-hour penalty 
per job that was ``based on a JHI time-motion study'' apparently 
conducted exclusively in a single industry (new home construction) and 
comprised of data from just the JHI study (Document ID 2322, Appendix 
G, Attachment A, p. A-8). OSHA could not determine whether it would 
actually supply new ``empirical evidence'' that would warrant a change 
from the preliminary estimate because the study was not submitted into 
the record. The commenter cites ``James Hardie Building Products, Inc., 
undated, pg. 15,'' which appears to align with an entry in the list of 
references to an undated ``James Hardie Labor Efficiency Manual,'' but 
that manual was not submitted into the record.
    Mr. Soyka recommended that OSHA use time-motion studies to derive 
the estimated productivity impacts.

    [. . . F]ew [of the productivity penalties estimated by OSHA] 
are supported by actual data (e.g., time-motion studies). OSHA 
should apply a more conservative approach that considers how work 
flow and task completion are likely to be affected by newly required 
changes to existing practices as well as entirely new activities 
(Document ID 2322, Appendix G).

    In addition, Mr. Soyka developed an alternative cost model that 
included additional productivity impacts that OSHA did not include. In 
this model Mr. Soyka ``assumed that wherever possible, company owners 
in the residential construction industry will outsource their 
compliance obligations to specific subcontractors . . . providing the 
products and services that might generate significant amounts of silica 
dust'' (Document ID 2322, Appendix G, p. 26). In this scenario, Mr. 
Soyka determined that the employer would require ``the subcontractor to 
relocate its work location outside the house(s) being constructed to a 
distance sufficient to ensure that silica dust concentrations remained 
minimal inside and around the house(s)'' and that ``relocating the 
materials and work giving rise to silica dust generation [. . .] would 
add substantially to the time required to complete the associated 
tasks'' (Document ID 2322, Appendix G, p. 30). He accounted for this 
additional time by increasing the productivity impact on the specialty 
subcontractors to seven hours per job, ``based upon time-motion studies 
conducted by James Hardie (James Hardie Building Products, Inc., 
undated, pg. 15)'' (Document ID 2322, Appendix G, p. 31).
    Mr. Soyka's model also included a productivity impact for ``wearing 
respirators to account for fatigue and adverse impacts on employee-to-
employee communication'' (Document ID 2322, Appendix G, p. 32).
    OSHA fundamentally disagrees with the Mr. Soyka's assumptions. Mr. 
Soyka's assumption that all silica-generating tasks need to be removed 
from the homebuilding site results from a misunderstanding of OSHA's 
statement that ``[i]n response to the proposed rule, many employers are 
likely to assign work so that fewer construction workers perform tasks 
involving silica exposure; correspondingly, construction work involving 
silica exposure will tend to become a full-time job for some 
construction workers'' (FR, 2013, at 56357) (Document ID 2322, Appendix 
G, p. 25). OSHA did not mean that silica-generating tasks will be 
subcontracted out and that subcontractors will be forced to perform 
these tasks off-site. Rather, the Agency was acknowledging that 
construction employers would likely consolidate the responsibilities 
for performing silica-generating tasks to as few workers as possible in 
order to limit exposures to peripheral workers.
    As mentioned previously, the ``time-motion studies'' performed by 
James Hardie, compiled in an unpublished reference, were not provided 
for public inspection. Moreover, the description of how those data were 
used in developing the model suggests that Mr. Soyka's relevant 
assumptions are not based on time-motion studies of how long it 
actually takes to perform specific tasks with controls added. Rather, 
it appears that Mr. Soyka assumed inflated times to perform the tasks, 
based on a misunderstanding of what the proposed rule required; in any 
case, it is not descriptive of the requirements for the final rule. Mr. 
Soyka's suggested approach contrasts with the estimates provided by 
CISC/Environomics, which accepted the limitations of the analytical 
exercise and agreed with most of the estimates in the PEA regarding the 
``variable'' productivity effect.
    Moreover, it should be noted that aside from weighing the possible 
competing forces on productivity in the course of a shift (e.g., more 
time for set up vs. less time required for clean-up), there is also a 
short-run/long-run phenomenon over a longer period as the standard 
comes into use. There may be a short learning curve until workers 
determine the most efficient way to perform a job when controls are 
introduced (Document ID 3581, p. 1700); in some cases the effect may be 
relatively larger until the method of performing a job is 
reconceptualized. Mr. Sokya criticizes OSHA for not recognizing ``the 
dynamic nature of construction'' (Document ID 2322, Appendix G, p. 19), 
but one obvious aspect of the dynamic nature of construction is that 
employers will be constantly adapting to changing circumstances and 
trying to find ways to

[[Page 16497]]

perform the job in the most cost-effective manner. In short, the Agency 
believes that a time-motion study of a particular task is neither 
necessary to determine approximately what the effect will be in the 
short-run, nor would it allow OSHA to determine what the long-run cost 
of integrating the controls will be.
    CISC and its consultant Environomics, as well as some other 
commenters, questioned OSHA's productivity-loss estimates associated 
with the required controls. CISC/Environomics claimed that overall OSHA 
``underestimated productivity losses associated with performing tasks 
using the prescribed controls by an amount roughly equal to the average 
equipment intensity of about 42 percent'' (Document ID 2320, p. 29). 
CISC/Environomics reported that this underestimation came largely from 
OSHA failing to account for what they termed ``fixed productivity 
impacts'' and for productivity impacts to equipment. Both of these 
concerns are discussed below.
    In its post-hearing brief, CISC/Environomics presented the results 
from a questionnaire and interviews conducted with employers and 
knowledgeable tradespeople; the results included a finding that ``the 
variable penalty percentages [. . .] were the same as or slightly 
larger than those that OSHA had estimated'' (Document ID 4217, p. 92). 
CISC/Environomics did not submit the questionnaire or the answers 
received, nor the details of the interviews, to the record so OSHA 
could not fully evaluate the findings or compare them to its own 
findings. Based on the available summary information it appears that, 
while CISC and OSHA's estimates for variable productivity costs were 
nearly identical, it is not clear that CISC's estimates took current 
compliance into account. CISC stated that its members felt that 
``something greater than zero variable productivity penalty should be 
estimated for masons using portable saws controlled with wet methods [. 
. .] and for heavy equipment operations using enclosed cabs and HEPA 
filters'' (Document ID 4217, pp. 92-93). OSHA acknowledges that there 
would be a productivity impact to comply with the requirements of the 
silica rule relative to using no controls for those activities. 
However, as shown in Chapter III of the FEA, Industry Profile, OSHA has 
found high levels of baseline compliance with the provisions of the 
rule for those activities. As is standard in OSHA's costing 
methodology, only costs above and beyond those incurred under current 
standards are attributable to the final rule.
    In addition, CISC argued that OSHA should take higher productivity 
impacts because ``in some fraction of these instances [(where controls 
would be required)], the controls are hellaciously difficult to use'' 
(Document ID 3580, Tr. 1321). The testimony goes on to give examples of 
such difficulties such as when ``building houses where the utilities 
are not yet in and the water is not yet in,'' when working in places 
where power is not readily available such as in parking garages or on 
scaffolding, and when doing work that requires wet methods outdoors in 
extremely cold temperatures (Document ID 3580, Tr. 1321-1322). A 
different commenter, the National Utility Contractors Association, 
similarly criticized OSHA's estimates for excluding additional water-
transportation costs: ``there is not always a water supply available 
which would require trucking large volumes of water to the job site 
which adds additional costs.'' (Document ID 3729, p.3)
    Given the fact that the majority of the silica-generating equipment 
requiring controls under this standard--such as tuckpointing grinders 
and concrete drilling equipment--require electricity, OSHA does not 
find merit in applying any productivity impact simply because the 
controls for those tools may also need electricity. If the employer can 
find a way to power the equipment, it can also power the controls when 
necessary. Similarly, employers must commonly transport water to 
worksites without it for cleanup and sanitation purposes, and OSHA's 
technological feasibility analysis explains why the amount of water 
required to generate the spray mist is not typically very significant. 
Although it seems plausible that wet methods would occasionally be used 
outdoors by some employers in weather cold enough to freeze the water 
mist used to control the silica dust, this is far from a common 
construction occurrence. Moreover, it is not entirely clear from the 
record that freezing mist would decrease productivity. OSHA's estimates 
of productivity impacts is intended to represent an average across all 
situations, and the tiny fraction of time wet methods will need to be 
used outdoors in extremely cold weather should not skew the average 
productivity impact.
    CISC/Environomics stated that there should also be a productivity 
impact on equipment rental or use as well as for the additional labor 
to operate that equipment longer. Environomics reported that a complete 
cost estimate of productivity loss would include not only the 
additional labor time required, but also the cost of having to rent 
equipment for a longer period of time.

    . . . Simply put, a productivity penalty for labor will 
translate to a productivity penalty for equipment. For example, if 
due to a labor productivity loss, the labor time required to 
complete a job increases from eight hours to eight hours and 15 
minutes, the equipment time required for job completion will also 
increase to eight hours and 15 minutes. Additional equipment rental 
costs will be incurred for the additional 15 minutes, or equipment 
owned by the employer will be delayed for use on another job by 15 
minutes (Document ID 2320, p. 29).

    This concern was reiterated both in its hearing testimony (Document 
ID 3580, Tr.1323) and in its post-hearing brief where Environomics 
stated that ``OSHA's analysis should add an equipment component to the 
costs associated with whatever productivity penalty is incurred in 
performing a construction task using the Table 1 controls'' (Document 
ID 4217, p. 91). OSHA agrees, in part, and recognizes that there can be 
a productivity impact for equipment (as well as for labor) for many 
tasks when there is a cost created by having to extend the rental time 
of the equipment.
    In the PEA, OSHA had estimated the labor productivity impacts 
associated with engineering controls to reduce silica exposure. For the 
FEA, the Agency has added a parallel cost for the equipment portion of 
the cost for a number of equipment categories. These are itemized in 
Table V-34 of the FEA. For example, for Task 15 (Demolition of concrete 
slabs, mesh-reinforcing, up to 3''deep), there is estimated to be a 2 
percent labor increase related to maintaining wet methods for dust 
suppression. In the original Means estimates, it was estimated that 
approximately 70 percent of the costs of the task were labor-related, 
divided between an operator and a laborer. This 2 percent additional 
cost is estimated to amount to $9.39 in added labor cost for an 
equipment operator and $7.84 for a laborer, or a total labor 
productivity cost per job of $17.23. For the FEA, OSHA is adding an 
additional cost item of $7.58 to reflect an opportunity cost, in the 
form of a prospective extended equipment rental cost, raising the total 
incremental estimated cost to $24.81 per task. As with the other 
construction engineering control costs, this additional cost item is 
task-specific.
    While OSHA judged that equipment productivity can be impacted 
negatively by the new rule for many tasks, there are two general 
categories for which the Agency determined that there would be

[[Page 16498]]

no impact on equipment productivity. The first broad category is short-
term, intermittent work in which the equipment and control are often 
idle. An example would be a plumber drilling holes in concrete. The 
equipment and control are sufficiently inexpensive (relatively 
speaking) that the construction employer or trade contractor (or 
possibly even the tradesperson) would typically own rather than rent 
the equipment and control. As discussed elsewhere in the FEA, OSHA 
determined that certain tradespersons, such as plumbers, electricians, 
and their helpers, are more likely to purchase their equipment, rather 
than renting it. OSHA estimated the cost of purchasing control 
equipment at twice the rental cost.
    The second category of tasks for which the Agency did not assess 
any equipment productivity impact is the group of tasks in which there 
is not a fixed ratio of labor to capital (capital in this case 
including rental costs). For example, as explained in the following 
unit cost discussion, Task 10 (as detailed in Table V-34 of the FEA) 
involves performing earthmoving as a heavy equipment operation task. In 
this case, while extra time by a laborer would be required to tend to 
the application of wet methods, such application would be done 
simultaneously with actually performing the earth-moving task. Thus, 
while wet methods for Task 10 would require an added labor cost 
(itemized as a ``productivity'' cost), it would not actually slow down 
the operation so as to require the longer period of use of the 
equipment that would impose an equipment impact.
    CISC/Environomics also argued that part of the productivity effect 
was fixed and would therefore need to be accounted for separately. This 
fixed component, CISC/Environomics reported, would be ``typically 
involving activities such as initial set-up and final take-down and 
clean-up of the control equipment, [which] often occur at the beginning 
and end of a job or work shift'' (Document ID 4217, p. 90, see also 
2320, p. 28; 3580, Tr. 1320). This would mean that shorter jobs would 
have a relatively larger percentage loss in productivity.
    Other commenters did not agree that there would be costs related to 
set up. During the hearings, Deven Johnson, of the Operative 
Plasterers' and Cement Masons' International Association, testified 
that the concrete grinding ``tools that are on the market today come 
integral with the capture device[. . .] The hose is attached to the 
grinder already. The electrical cord is attached to the motor already. 
[. . .] You simply plug it in and start using it [. . .] there's no 
setup time'' and that for ``a walk-behind concrete diamond-bladed saw 
for cutting slabs, the setup time is, make sure there's gas in it and . 
. . hook a water hose up to it and turn the water on'' (Document ID 
3581, Tr. p. 1699). During the hearing, Manafort Brothers described a 
wheel-based machine used to suppress dust during demolition operations, 
which was simply wheeled onto the worksite and hooked up to a water 
supply and electrical source (Document ID 3583, Tr. 2430), and the 
Building Trades Construction Department (BCTD) of the AFL-CIO submitted 
an extensive list of available tools that included the controls 
required by the rule that would require little or no set up (Document 
ID 4073, Attachment 4a).
    Based on the evidence in the record, OSHA determined that any time 
needed to set up the engineering controls required by this rule is 
adequately accounted for in the productivity impacts the Agency has 
included, particularly in light of the fact that OSHA is not making any 
adjustment to account for productivity improvements that are likely to 
result from this rule (see the discussion of comments identifying 
productivity improvements later in this section). Environomics' 
inclusion of both a ``fixed'' productivity impact as well as a 
``variable'' productivity impact, without recognizing offsetting 
productivity benefits identified by other commenters', results ins a 
significant overestimate of the productivity impact.
Public Comments Suggesting That OSHA had Overestimated the Productivity 
Impacts Associated With Engineering Controls
    BCTD strongly disagreed with CISC's estimates about productivity 
decreases resulting from the rule, stating in their post-hearing brief:

[a]ll that [CISC] offered to support these significant increases [in 
the productivity impact] is an explanation of how its approach to 
calculating productivity differs from OSHA's and a few examples, 
such as:
    So in the case of the carpenters with the dust extraction 
equipment on the drill and the HEPA vacuum, the carpenter takes a 
little bit longer to do his hole-drilling task because he's got to 
attach the equipment to the drill. He's got to attach the hose to 
the HEPA vacuum. He's got to walk over before he drills and he's got 
to turn on the HEPA vacuum. Then after he drills, he's got to turn 
off the HEPA vacuum. He's got to periodically empty the HEPA vacuum. 
He's got to worry about the vacuum hose from the drill to the vacuum 
getting kinked and all that sort of thing. So the job takes a little 
bit longer. Tr:1317-18.
    CISC offered no evidence that its analytical approach is more 
accurate than OSHA's. Moreover, this description of how its 
hypothetical carpenter would deploy control technology assumes the 
employer would select the most cumbersome and inefficient technique 
available, rather than taking advantage of the range of more 
suitable and less costly tools that are readily available on the 
market. See, e.g., Ex. 4073, Att.7a (ROI: hand-held drill with 
integrated dust collection) (Document ID 4223, pp. 55-56).

    BCTD also took exception to the fact that ``CISC acknowledged that 
`there may be a productivity net gain in terms of cleanup from using a 
control,' Tr:1319 (Sessions), [but did] not appear to have taken 
potential gains into consideration when estimating its lost 
productivity cost'' (Document ID 4223 pp. 55).
    Dr. Ruth Ruttenberg highlighted the various areas where the PEA may 
have overestimated the negative productivity effect of engineering 
controls in construction. She stated that the assumption of a negative 
impact on productivity

    . . . is yet another example of OSHA erring on the side of being 
conservative in cost estimates. Despite the fact that some who were 
interviewed suggested there could be a positive impact on 
productivity, OSHA's PEA assessed anywhere from 0 percent to a 5 
percent penalty in productivity loss as a result of OSHA compliance 
with the proposed silica rule. (PEA, p. V-123-124) The impact of an 
assumption of lost productivity can be profound, and OSHA 
acknowledges this: ``. . . the magnitude of the productivity impacts 
can substantially change the estimate of the overall cost increase 
associated with controls'' (PEA, p. V-131).
    Despite the fact that OSHA leaves likely productivity increases 
out of its calculations, it does point to opportunities to increase 
productivity with dust control. [. . .]
    Limiting dust increases visibility for workers. (PEA, p. V-126) 
Vacuum systems speed up drilling because continuous removal of drill 
cuttings from the hole, reduce the need for workers to periodically 
stop and clean. (PEA, p. V-128) And the list goes on. OSHA's cost 
estimates are conservative, and high, when it comes to productivity 
impact (Document ID 2256-A4, p. 7).
Productivity Improvements
    In addition to comment that the productivity loss due to this rule 
would be minimal, OSHA also received considerable comment to the record 
that the controls would improve productivity in a number of ways the 
Agency had not factored in--for example by reducing clean-up time by 
capturing dust at the source, improving worker comfort and morale, and 
encouraging innovation.

[[Page 16499]]

Productivity Improvements--Reduced Clean-Up Time
    Testimony at the public hearings by the International Union of 
Bricklayers and Allied Craftworkers on the experience by union members 
with engineering controls suggested that use of controls may boost 
productivity by reducing the amount of dust that needs to be cleaned up 
during a given shift. The following is a hearing dialogue between Chris 
Trahan of BCTD, and Sean Barrett of the International Union of 
Bricklayers and Allied Craftworkers:

    MS. TRAHAN: [. . .] In your experience is there any productivity 
gains or benefits that you can describe?
    MR. BARRETT: I can. These machines, when running correctly, when 
[. . .] the vacs are regulated, the filters are running good. You 
can run that machine until 3 o'clock in the afternoon, shut it off, 
and go home. [. . .] If [the machine is] not [running correctly], 
you constantly got to keep going back and cleaning up what you 
already did. You're losing productivity. And over the course of [. . 
.] a month you're talking 40 man-hours. You're talking a--paying a 
guy for a week. It's--that's not the case at all [if dust controls 
are functioning]. You would actually increase productivity by having 
the right equipment there and not have people have to keep coming 
back or jimmy-rig little things to try to get by. Just do it the way 
it was designed, and you'll get a lot farther. . . . (Document ID 
3585, Tr. 3055-3057).

    Deven Johnson of the Operative Plasterers' and Cement Masons' 
International Association elaborated on the potential time savings of 
some of the new engineering controls:

One of the other things that collecting the dust from these operations 
on the front end does, it saves time on cleanup. Some of the industry 
people have said that it's prohibitive to do that because it takes more 
time to collect the dust. That's also not true. If you're collecting 
the dust as it's generated and it's going into a HEPA-filtered 
container, it's not being blown all over the job site, you don't need 

    anybody else to clean it up (Document ID 3581, Tr. 1594).Walter 
Jones of the Laborer's Health and Safety Fund testified that, for some 
tasks, reducing or eliminating the need to clean up after a job can 
dramatically increase productivity, in this case by one-third:

    We had the Bricklayers here a few days ago and they were talking 
about their ability to work till 3:00, because they did not have to 
clean up. Instead, when they use non-dust controlling or capturing 
devices, they would have to stop right after lunch in order to begin 
cleaning up. So we're looking at adding a few more hours to the 
workday. So to me, in my mind, they're way more productive (Document 
ID 3589, Tr. 4246).

    Joel Guth, President of iQ Power Tools and a mason contractor, 
testified that he had been able to document the savings in clean-up 
time.

    In certain industries we've been able to measure the time 
savings from cleaning up the silica dust [. . .] It saves them one 
to two to three hours a day in cleanup time because they don't have 
to wash down the house or wash the windows or wash the bushes where 
they're inherently dry cutting (Document ID 3585, Tr. 2981).

    Scott Schneider, CIH, Director of Occupational Safety and Health. 
Laborer's Health and Safety Fund of North America, discussed how 
engineering controls contribute to a more productive workplace:

    When you control the dust and you don't have--you're not 
breathing it into your lungs, but you're also not spraying it all 
over the construction site, all over the sidewalk, and you have to 
clean it up, there's a lot of other costs involved in not 
controlling. So I think we're going to realize those benefits by 
implementing the standard (Document ID 3589, Tr. 4277).
Productivity Improvements--Improved Worker Comfort
    OSHA also heard a good deal of testimony suggesting that 
productivity will be improved through the use of engineering controls 
due to improving the working conditions for workers.
    Mr. James Schultz of Wisconsin Coalition of Occupational Safety and 
Health described the physiological and practical benefits of 
introducing or enhancing engineering controls:

    I think if you would work in the work environment that was less 
dust or hopefully dust free, it would definitely increase the amount 
of productivity just because so much of the time you're spending 
wiping the dust off your brow because it's falling into your eyes or 
something like that. Even if you have the respirator, it still 
interferes with your vision and things like that. So a cleaner 
environment would definitely be more productive just because [. . 
.], you spend less time trying to think about how you can protect 
yourself from this hazard, and I know myself, after working in the 
place for many years, I've started to have breathing problems and so 
if you can eliminate those breathing problems, if you can breathe 
freely, you're also going to be much more productive because you're 
not going to stop because you have [to] wheeze or go stand outside 
to get some fresh air for awhile or those types of things (Document 
ID 3586, Tr. 3253-3254).

    Deven Johnson, mentioned previously, testified about the human 
effect of controlling silica as well:

    Another thing is, an individual who is working in an environment 
where [. . .] he or she is constantly bombarded with concrete dust 
all day long, your productivity drops as you get more and more 
miserable as the day goes on. Commonsense would dictate, if you're 
not blasting me in the face with dust and sand and silica for eight 
hours a day, that I'm going to feel physically better and I'm not 
going to be as tired and exhausted and pissed off as I normally 
would be at the end of the day. Your productivity goes up[. . .]. 
(Document ID 3581, Tr. 1594-1595).

    Mr. Javier Garcia Hernandez, from National Council for Occupational 
Safety and Health/Equality State Policy Center/Laborsafe, testified on 
the cognitive factors that affect productivity, and why engineering 
controls should aid productivity:

    . . . as a construction worker, I highly believe that we're more 
productive when we are protected[. . . .]. We spend less energy 
focusing on how to protect ourselves. Just imagine you're working in 
a roomful of dust and you're just trying to either close your eyes 
or cover your mouth so the less you breathe. So you're constantly 
thinking about how to breathe less dust but if you have the 
respirator or the wet, the controlled area, whether it is water or 
respiratory protection, you're much more productive because our mind 
is less occupied in how to protect ourselves and we spend that time 
that we would have spent protecting ourselves working (Document ID 
3586, Tr. 3248-49).

    Todd Ward, a bricklayer, testified that workers have some awareness 
of the hazards of dry cutting blocks and that

    . . . when [workers] on the job [are] dry cutting they know--it 
affects morale as well when they know [. . .] they have some 
safeguards and they're protecting their lungs. So there is an 
increased productivity when you have a good morale then on the job 
(Document ID 3585, Tr. 3057).
Productivity Improvements--Innovation
    OSHA received comments on the fact that OSHA standards often lead 
to innovation.
    The Laborers' Health and Safety Fund of North America pointed out 
that ``[j]ust about every OSHA standard has had a look-back that has 
shown [that] industry has innovated to meet the new standard'' and 
continued, saying that ``[w]e believe a new OSHA standard with a lower 
PEL will spur innovation in the construction industry to meet the 
challenge'' (Document ID 3589, pp. 4183-4184).
    Charles Gordon observed that ``reality is that the new technology 
will increase productivity faster, so that the actual costs will be 
much less than predicted'' (Document ID 3855, Tr. 3815).
Conclusions Regarding Productivity Impacts
    In summary, while some commenters have asserted that OSHA has 
underestimated the productivity penalties of using engineering controls 
in construction, other evidence in the record suggests that the 
aggregate net

[[Page 16500]]

productivity effect of implementing engineering controls could either 
be neutral, or possibly positive. In the absence of detailed 
quantitative data on these various potentially offsetting effects, OSHA 
has conservatively chosen to retain its percentage estimates from the 
PEA, while adding some additional productivity impacts that will 
increase not only labor costs but also equipment costs.
    There is one exception: OSHA has removed the productivity impact 
that it had included in the PEA for drywall installers. As explained in 
the unit cost discussion, the Agency has determined from the record 
that there is no economic reason why drywall installers would now use 
silica-based drywall installation--the U.S. market has shifted entirely 
to a silica-free compound (Document ID 2287, p. 38; 2296, Attachment 1, 
p. 30; 1335, pp. 3-4, 7, 10). Therefore, there is no longer a logical 
basis for a assigning a productivity loss to workers performing this 
task.
    Table VII-12 summarizes the labor productivity estimates. As 
discussed previously, while empirical quantitative data are quite 
limited on productivity, it is possible to gauge the relative 
productivity impacts across the principal control options. For example, 
OSHA judged that there are no productivity impacts for certain 
controls, such as mobile crushing machines. On the other hand, OSHA 
found that the controls required for tuckpointers and grinders may 
result in additional time being spent setting up and maintaining 
controls over the course of a workday. In Table V-34 of the FEA, 
productivity impacts, or ``lost production time,'' are shown by task 
and are factors in OSHA's estimate of incremental cost per day.
    As discussed, OSHA has retained most of its original estimates of 
the productivity effects from the PEA. In some cases, however, Table 1, 
which forms the basis for the equipment categories listed in Table VII-
12, was changed from the PEA in response to comment. (see Methods of 
Compliance in this preamble for further discussion on the changes to 
Table 1). In other cases, OSHA received clarification on the manner of 
exposure and added elements to Table VII-12, but did not adjust the 
productivity impact. For example, OSHA received very specific comments 
on tasks involving portable masonry saws used to cut fiber cement 
materials (e.g., ``Hardie board''), and this is reflected in specific 
descriptions in Table 1 and in Table VII-12, but the estimated 
productivity impact for ``masonry cutting using portable saws'' remains 
the same. Similarly, the Table 1 task that included ``heavy equipment 
operations'' in the proposed rule has been broken out into two groups: 
(1) Heavy equipment operators and ground crew laborers used for 
activities such as grading and excavating that will not involve 
demolition or other uses that will abrade or fracture silica-containing 
materials; and (2) heavy equipment operators and ground crew laborers 
involved in demolition or the abrading or fracturing of silica-
containing materials. These two categories are now estimated to have 
productivity impacts of two and three percent, respectively.

[[Page 16501]]

[GRAPHIC] [TIFF OMITTED] TR25MR16.052

Productivity Impact Estimates, by Equipment Category
Rock and Concrete Drilling
    This equipment category includes the following Table 1 tasks:
     Dowel drilling rigs for concrete; and
     Vehicle-mounted drilling rigs for rock and concrete
    This equipment category covers a range of drilling activities using 
truck-mounted and similar drilling equipment, such as quarry drills and 
crawler-type drills. Dust control requires the use of either a dust 
collection system or wet drilling methods. Studies of the effectiveness 
of available dust collection systems have not addressed performance 
issues, but ERG judged that their use does not affect drilling 
productivity. While workers must service the dust control equipment 
during the workday, this activity generally does not affect the rate of 
drilling, except perhaps for short-duration jobs. The wet drilling 
methods are integrated into drilling equipment and also should not 
adversely affect the drilling rate. Thus, OSHA estimates that there 
will be no lost production time for these tasks.
Tuckpointers and Grinders
    This equipment category includes the following Table 1 tasks:
     Handheld grinders for mortar removal (i.e., tuckpointing); 
and
     Handheld grinders for uses other than mortar removal
    According to ERG's search of the literature, grinding tools can be 
retrofitted with dust control shrouds that connect to a vacuum system 
(Buser, 2001 & 2002, Document ID 0577). Studies on the use of these 
controls indicate that extra time is required to install the shroud and 
periodically

[[Page 16502]]

clean, empty, or replace the vacuum drums, filters, or bags. The 
estimated time to install the shroud may be as short as five minutes, 
although some types of shrouds take longer to install. Once installed, 
however, the shroud can be left in place for the work at that location, 
so this activity need not take place at the initiation of each grinding 
job.
    For interior jobs and for exterior work that requires site cleanup 
of grinding debris, the additional work time required to use a vacuum 
system might be partially offset by savings in the time required to 
seal work areas (to prevent dust migration) and to clean the work area 
after task completion. Overall, clean-up times will vary depending on 
the size of the job site, the quantity of grinding debris, and the 
strength and capacity of the vacuum.
    Grinding without a dust-control shroud can generate clouds of dust 
that might impair a worker's views of the grinding area. Whereas metal 
shrouds also block the view of the grinding area, plastic shrouds allow 
workers a view of the work area. Some contractors have noted, however, 
that use of shrouds does not allow for the precision required for 
certain tasks, such as grinding an inside corner (Lattery, 2001, 
Document ID 0777).
    For exterior jobs where cleanup is not required and where the work 
area is not sealed, the use of vacuum equipment is likely to decrease 
productivity for the amount of time required for servicing the vacuum 
collectors. If, for example, five minutes were required to empty the 
vacuums every two hours, production time would decline about 4 percent, 
due simply to dumping the accumulated dust.
    At some construction sites, vacuums have been used during the 
grinding process, but without shrouds. In these cases, one worker 
typically holds the vacuum nozzle near the grinding tool, which another 
worker operates. Switching to shrouds with a direct vacuum attachment 
would eliminate the need for this assistant and is a more productive 
operation.
    Manufacturers and vendors cited other benefits from using the 
shroud-vacuum systems. Because dust does not build up on and clog the 
surface of the grinding wheel, the wheels last longer, resulting in an 
approximate 40 percent savings on the grinding discs (Eurovac, 2001, 
Document ID 0688). Another source contacted by ERG estimated that 
shrouds can increase the abrasive life of a grinding wheel by more than 
500 percent (Buser, 2001 & 2002, Document ID 0577). In this regard, 
workers would spend slightly less time replacing wheels over the life 
of the equipment.
    OSHA concluded that while the productivity impacts of vacuum 
systems can sometimes be partly offset by other factors, net 
productivity impacts are likely to remain negative. For exterior work, 
productivity is clearly lower when workers use a vacuum system. 
Overall, based on ERG's research, OSHA's final cost estimates include a 
5 percent impact for lost production time associated with grinding 
operations in construction. This productivity impact is identical to 
the impact estimated for this activity in the PEA.
    For a tuckpointing project, NIOSH researchers examined the use of 
vacuum system controls at a large college building complex (Gressel et 
al., 1999, Document ID 0718). Workers used a shroud-vacuum system with 
an integral impeller and a fabric dust collection bag. This system 
required emptying the collection bags about once an hour. The authors 
reported some problems caused by blocking and kinking of the hose and 
occasional separations of the hose from the tool. Some of these 
problems can be attributed to the design of the dust control system and 
might be rectified by future design innovations. Overall, the vacuum 
control systems appeared to reduce worker output.
    Manufacturers and vendors contacted by ERG estimated that 
polyurethane shroud-vacuum systems with tuckpointing equipment, similar 
to those used with hand-held grinders, actually enhance productivity. 
Among the reasons provided for productivity improvements were: (1) 
Fewer workers were required; (2) cleanup times were reduced; (3) 
workers had improved visibility of the work surface; and (4) blades 
last longer (Buser, 2001 & 2002, Document ID 0577; Caperton, 2002, 
Document ID 0580; Eurovac, 2001, Document ID 0688; Nash and Williams, 
2000, Document ID 0829). These observations on productivity applied to 
tuckpointers with 2- to 8-inch diameter wheels. In addition, positive 
effects on worker productivity have also been reported for shrouds that 
fit on 5-inch and 7- to 8-inch (18-lb) tuckpointers with integrated 
dust-collection systems since equipment without integrated dust-
collection systems require that an additional worker be present to 
continually vacuum dust away from the work area (Document ID 0577). On 
the equipment that can be used with the tuckpointers with 5- to 8-inch 
wheels, an impeller inside the tool housing pushes dust down a hose 
into a reusable dust-collection bag (Document ID 0577). One vendor 
estimated that the operational productivity of these tools is no 
different from that of the same tool without dust control capability. 
Workers would still be required to periodically empty dust bags, 
although other clean-up time might be somewhat reduced (Document ID 
0580). Because tuckpointing work is almost exclusively exterior work, 
however, clean-up is often not required.
    Based on the considerations for hand-held grinding tools discussed 
above and the findings from the NIOSH tuckpointing study, OSHA judged 
in the PEA that use of a vacuum system during tuckpointing operations 
would impose, on average, a 5 percent negative productivity impact. 
Based on these findings and because manufacturer optimism about any 
positive productivity impacts has not been documented in controlled 
studies, OSHA included the same 5 percent negative productivity impact 
for tuckpointing tasks in the FEA.
Heavy Equipment Operators and Ground Crew Laborers
    This activity includes the following Table 1 tasks:
     Heavy equipment and utility vehicles used to abrade or 
fracture silica-containing materials (e.g., hoe-ramming, rock ripping) 
or used during demolition; and
     Heavy equipment and utility vehicles for tasks such as 
grading and excavating but not including: Demolishing or abrading or 
fracturing silica-containing materials \41\
---------------------------------------------------------------------------

    \41\ Heavy equipment operations (grading and excavating) was 
referred to as earth moving in the PEA and in comments. The term has 
been updated for this analysis and used throughout for the sake of 
consistency and to avoid confusion.
---------------------------------------------------------------------------

    The control method proscribed in the proposed silica standard was 
to enclose and ventilate the operator's cab. The requirement for an 
enclosed cab is only retained in the final standard with respect to the 
use of heavy equipment used to abrade or fracture silica-containing 
materials or used during demolition. Final Table 1 allows employers to 
control dust from heavy equipment used for other purposes (e.g., 
grading or excavating) by using wet methods.
    Using an enclosed cab on heavy construction equipment will not 
require maintenance beyond the general maintenance necessary to 
maintain the integrity of the cab enclosure. Therefore, OSHA estimated 
in the PEA that no productivity loss will be incurred for this control.
    In the case of heavy equipment operations, CISC/Environomics 
estimated that there would be a one percent productivity penalty for

[[Page 16503]]

enclosed cabs, due to communication issues and the need to unclog HEPA 
filters (Document ID 4217, p. 93). For several reasons OSHA is not 
persuaded that the factors CISC cites would result in a net 
productivity loss for enclosed cabs on heavy equipment.
    First, it is not clear that communication issues are being created 
by setting some minimal standards for enclosed cabs. Information 
supplied in the record indicates that there are alternate means of 
communication beyond shouting from the cab to the front-line workers 
outside the cab, including hand signals (Document ID 3583, Tr. 2441) 
and existing wireless communication systems (Document ID 0805, p. 4; 
2262, p. 28). Many of these work environments are noisy, which seems to 
make alternate means of communication desirable, if not required.
    Second, it appears that it may be more economical and desirable for 
workers to operate in a climate-controlled cab and that equipment with 
enclosed cabs has become standard in the construction industry. In 
fact, OSHA has determined that relevant heavy equipment currently comes 
with an enclosed cab as standard equipment (Document ID 3813, 3814, 
3815, 3816), and in pricing construction jobs, RS Means included a cab 
as a standard equipment (meaning that it was already included in the 
equipment cost, not an added engineering control). In any case, the 
fact that cabs are standard suggests that potential buyers do not view 
the presence of a cab to be undesirable. While Environomics 
acknowledged this possibility at the hearings, their judgment remained 
that there would be a net productivity loss (without providing 
information on how these offsetting considerations were being 
incorporated) (Document ID 3580, Tr. 1434-1435). While OSHA is not 
persuaded that the evidence in the record supports Environomics 
conclusions, their argument is largely moot. Any productivity impact 
would result only from the addition of new controls, but enclosed cabs 
appear to have become standard on the relevant equipment, meaning that 
in most cases employers would not have the option of using open cabs 
even if OSHA's new rule was not in effect. Thus, there can be no 
productivity impact attributed to the requirement for a cab.
    Although OSHA is not including any productivity impact to account 
for enclosed cabs, final Table 1 requires water, or other dust 
suppressants, during specified heavy equipment operations in order to 
protect workers outside the cab and as an alternative method of 
protecting operators for activities that do not involve silica abrading 
or fracturing. OSHA has therefore, as indicated in Table VII-12, added 
a 2 percent productivity impact for heavy equipment tasks involving 
grading and excavating, and 3 percent during demolishing, abrading or 
fracturing silica-containing materials. OSHA judged that the abrading, 
fracturing, and demolition-related tasks tend to be relatively dustier, 
and would therefore require relatively more labor to administer.
Hole Drilling Using Handheld or Stand-mounted Drills
    This equipment category includes the Table 1 task ``handheld and 
stand-mounted drills (including impact and rotary hammer drills).''
    This category includes workers in the construction industry who use 
handheld drills to create clearly defined holes for attachments (e.g., 
anchors, bolts, hangers) or for small openings for utility pass-
throughs in concrete and other silica-containing construction 
materials. Workers use common electric drills, pneumatic drills, 
handheld core drills, stand-mounted drills, rotary drills, rotary 
hammers, percussion hammer drills, or other impact drills to drill 
holes. With regard to core drills, only small, handheld core drills 
with bits up to a few inches in diameter are included in this category. 
This discussion does not address the use of portable and mobile hole 
saws used to produce large holes or openings. That equipment is covered 
in the discussion of Masonry and Concrete Cutters Using Portable Saws.
    Handheld and rig-mounted drills can be equipped with local exhaust 
ventilation to effectively capture dust generated when drilling small 
diameter holes. Larger core drills, also referred to as core saws, are 
more frequently used with water as a coolant to extend the service life 
of the drill bit, as well to suppress dust.
    One rock-drill manufacturer asserts that use of vacuum systems 
speeds drilling by continuously removing the drill cuttings from the 
hole, making it unnecessary for workers to periodically stop drilling 
to accomplish this task (Atlas-Copco, 2001, Document ID 0542). On the 
other hand, the connection and servicing of the vacuum equipment 
requires incremental work that could reduce productivity. If the 
construction project at hand involves interior work, this impact might 
be offset by reductions in the time necessary for cleanup (i.e., 
interior work would require cleanup, while exterior drilling probably 
would not). In the PEA, OSHA applied a 2 percent productivity impact 
where this task is performed and did not receive comment suggesting 
that this estimate was too low, so OSHA retains the same 2% 
productivity impact in estimating compliance costs in the FEA.
Jackhammers and Other Powered Handheld Chipping Tools
    This equipment category includes the Table 1 task ``Jackhammers and 
handheld powered chipping tools.''
    Silica exposures generated during pavement breaking, concrete 
demolition, and other concrete work using jack hammers and other 
handheld powered chipping tools (including pavement breakers and other 
similar tools) are controlled through the use of wet or dry methods.
    Regarding wet methods, because the work area generally cannot be 
presoaked effectively (i.e., dust is generated once impact drillers 
break through the surface), OSHA judged that adequate dust control 
requires a constant spray of water to the work area. Thus, dust control 
requires that a water sprayer be mounted onto the jackhammer (or that a 
mobile sprayer be set up that can move along with the work). 
Alternatively, a crew member can use a water hose to spray and wet the 
concrete and asphalt surfaces being broken, although the associated 
productivity loss could be substantial, and, for that reason, OSHA 
believes that construction firms would likely try to avoid that 
approach.
    However, OSHA judged that the incremental productivity impact from 
the spraying activity is modest because various crew members could 
occasionally be enlisted to keep the water spray directed in the 
correct location. Further, because of the interactive nature of the 
various crew member activities, the time to move the water sprayer is 
unlikely to affect the overall crew output. In addition, incremental 
cleanup costs generally would not be significant since most drilling 
projects are performed outside. Nevertheless, to allow for some 
incremental work related to supplying water and positioning the spray 
when wet methods are used, as was the case in the PEA, for the FEA OSHA 
estimated a 3 percent productivity impact for this equipment category 
when wet methods are used.
    A separate, higher, productivity impact was defined for use of dry 
methods for activities where jackhammers and other handheld powered 
chipping tools are used. Dry methods are somewhat less flexible and 
require a shroud for the close capture of dust as it is generated 
during operations. Workers also periodically have to empty

[[Page 16504]]

the vacuum bags in which the dust accumulates. Thus, as discussed above 
with respect to the use of a shroud for grinding and tuckpointing, 
these controls are judged to generally have a greater productivity 
impact during operations and, consistent with the PEA, OSHA assigned a 
5 percent productivity impact to use of this control method for this 
equipment category.
Masonry and Concrete Cutters Using Portable Saws
    This equipment category includes the following Table 1 tasks:
     Handheld power saws (any blade diameter);
     Handheld power saws for cutting fiber-cement board (with 
blade diameter of 8 inches or less);
     Rig-mounted core saws or drills;
     Walk-behind saws; and
     Drivable saws
    Drivable saws and walk-behind saws have an integrated water tank, 
and the sawing is almost always done wet (see FEA Chapter IV, 
Technological Feasibility). Wet sawing keeps the blade from 
overheating, with the water acting as coolant. Rig-mounted core saws 
used to drill larger diameter holes in concrete are typically used with 
water as a coolant to extend the service life of the bit, as well as to 
suppress dust.
    As has been noted, most portable hand-held concrete saws are 
designed with wet-sawing capability (see Chapter IV, Technological 
Feasibility of the FEA). These saws have a water hookup for a hose 
attachment, but might also be used for dry cutting. (Dry-cut diamond 
blades for dry cutting are available; these are made especially so that 
the tips do not separate during dry cutting.)
    A construction equipment distributor judged that there are no 
operational productivity advantages for dry cutting, as opposed to wet 
cutting (Healy, 2002, Document ID 0726). Wet cutting, however, requires 
access to water (water line or pressurized tank), and some time is 
needed to connect the equipment (although OSHA received a number of 
comments saying that this hook up is very simple and not time 
consuming--see ``Public comments suggesting that OSHA underestimated 
the productivity impacts associated with engineering controls'' earlier 
in this section for more detail). In addition, the water hose hookup 
may be cumbersome and interfere with the work (Healy, 2002, Document ID 
0726). For these reasons, as was estimated in the PEA, for the FEA, 
OSHA assigned a cost of 2 percent in lost production time for equipment 
in this category.
    For the final rule, the Agency has clarified in Table 1 that hand-
held circular saws with a blade diameter of eight inches or less 
specially designed for cutting fiber cement board can be used outdoors 
without respiratory protection, when equipped with a local exhaust 
ventilation. The productivity impact for this group is also estimated 
at 2 percent because, although it does not have an impact on job 
performance, it involves some set-up time and incremental maintenance.
Masonry Cutters Using Stationary Saws
    This equipment category includes the Table 1 task ``Stationary 
masonry saws.'' Stationary saws for masonry, brick, and tile cutting 
come equipped with water systems for wet cutting, which is the 
conventional, baseline control method for this type of work. Some 
modest incremental time is needed to provide for and connect the water 
supply and to maintain the water nozzles and spray system. This 
incremental time was the basis for OSHA to estimate a 2 percent cost in 
lost production, both in the PEA and in the FEA.
Millers Using Portable or Mobile Machines
    This equipment category includes the following Table 1 tasks:
     Walk-behind milling machines and floor grinders;
     Small drivable milling machine (less than half-lane);
     Large drivable milling machines (half-lane and larger with 
cuts of any depth on asphalt only and for cuts of four inches in depth 
or less on any other substrate)
    The activities performed using equipment in this category range 
from cold planing and cleaning of asphalt to surface planing or 
grinding of concrete. In large-scale projects, such as street 
resurfacing, baseline practices are judged to control silica dust 
exposures. No additional controls would be needed, and therefore no 
negative productivity impacts are expected.
    While some grinding machines designed for milling concrete surfaces 
have built-in dust collection or wet-method systems, others must be 
attached to external vacuum equipment. ERG reviewed the available 
literature and found no evidence that the grinding operation is slowed 
when such vacuum equipment is attached. Nevertheless, workers must 
devote some time to setting up equipment, changing vacuum bags or 
barrels, and cleaning filters. On the other hand, using an LEV system 
to capture dust as it is generated reduces the time required for 
cleaning up the settled dust from the surfaces following completion of 
the grinding task. OSHA estimated in the PEA that there would be a 2 
percent productivity impact for milling using wet methods and a 5 
percent productivity impact when using LEV systems.\42\ These estimates 
have been retained for the FEA.
---------------------------------------------------------------------------

    \42\ For the FEA, milling operations using LEV are accounted for 
under grinding operations, as indicated in Table V-24.
---------------------------------------------------------------------------

Mobile Crushing Machine Operators and Tenders
    This equipment category comprises the Table 1 task ``Crushing 
machines.''
    OSHA projected in the PEA that there would be no productivity 
impact for this equipment category. The Table 1 requirements for this 
machinery have changed in the final rule, but OSHA's conclusion that 
there will be no productivity impact remains the same. Final Table 1 
requires employers to protect employees through a combination of 
sprayers and requiring the operator to operate the machinery from 
within a ventilated booth or at a remote control station. Once 
installed, the sprayer systems will be part of the crushing machine 
operation and will not impact production rates. For the purpose of the 
economic analysis of this rule, OSHA has accounted for additional costs 
for use of the ventilated booth. Because the booth can be located close 
to the machinery, there would not be productivity loss from the 
operator having to travel to a different location for operation. In 
most cases the booth can be set up quickly once at each location, so in 
most cases there will not be any significant productivity loss 
associated with the use of the booth.
Baseline and Incremental Unit Control Costs
    Table V-34 in the FEA, and presented as Table VII-13 in this 
section, summarizes the control method and costs per day for each 
representative construction job. These costs include incremental 
equipment costs and indirect labor costs due to productivity impacts 
(decreases in productivity associated with the use of the control 
equipment).
    Note that the only silica tasks in Table V-34 of the FEA considered 
to have short-term infrequent work where the employee would own the 
equipment are Task 11: Hole drilling using hand-held or stand-mounted 
drills and Task 18: Masonry cutting using portable saws--II. Note also 
that all the indoor tasks in Table V-34 of the FEA have an additional 
daily control equipment cost of $1.67 for a fan.

[[Page 16505]]

    Table V-35 of the FEA summarizes the baseline costs and incremental 
control costs from Tables V-30 and V-34, of the FEA, respectively, for 
each representative silica-related job in OSHA's silica construction 
cost analysis. The control cost (defined as incremental control costs 
per day) are shown in Table V-35 of the FEA as a percentage of the 
baseline daily job costs. As the incremental control costs were 
obtained from Table V-34, they are just the sum of additional labor and 
equipment costs associated with the use of silica controls, including 
the labor and equipment productivity impacts of the use of the silica 
controls.
    As is evident from Table V-35 of the FEA, these incremental control 
costs can range from 0.3 percent to 7.8 percent of the baseline job 
cost. The magnitude of the productivity impacts can substantially 
change the estimate of the overall cost increase associated with the 
silica dust controls.
    Table V-36a of the FEA presents the weighted average of control 
costs by task category for outdoor tasks. OSHA defined ``weights'' for 
each job category (column ``Relative Frequency Within Categories'') 
based on the projected relative applicability of the controls and/or 
tasks within each category (as determined in the technological 
feasibility analysis in Chapter IV of the FEA). These percentages did 
not change from the PEA except for the two tasks that have each been 
further partitioned into multiple tasks in the final rule: Heavy 
construction operators and masonry cutters using portable saws. Heavy 
equipment operators are subdivided into tasks that involve fracturing, 
abrading, or demolishing silica-containing materials such as masonry or 
concrete, that require use of wet methods whenever workers other than 
the equipment operator are present, and tasks that involve use of heavy 
equipment for earthmoving and excavation of soil, that require wet 
methods only as necessary to minimize fugitive dust. Masonry cutters 
using portable saws are subdivided into five categories: (1) Handheld 
power saws such as cutoff saws; (2) handheld power saws for cutting 
fiber-cement board with blade diameters of less than eight inches; (3) 
walk-behind saws; (4) drivable saws; and (5) rig-mounted core saws. Wet 
methods are specified as a control method for all use of portable saws 
except for handheld power saws for cutting fiber-cement board, for 
which LEV rather than use of water to suppress dust is required. The 
labor cost as a percentage of project costs--which, as subsequently 
shown, is a critical factor in calculating the total value of all 
silica-generating construction activities--is derived from Table V-30 
of the FEA.
    Table V-36b of the FEA presents the weighted average of control 
costs by task category for tasks indoors or in enclosed areas (``indoor 
tasks''). The procedures are identical to those used in Table V-36a of 
the FEA, and the only difference is that the total incremental costs as 
a percentage of baseline costs are higher due to the addition of the 
cost of a fan for indoor tasks.
    Once the total value of all silica-generating construction activity 
is calculated for each task, as shown in Table V-44 of the FEA, the 
incremental costs associated with each task category as a percentage of 
baseline costs (from Tables V-36a and V-36b of the FEA) will determine 
the costs that the engineering control requirements in the final 
construction standard add to the costs of construction activity--that 
is, the incremental costs of the resulting reduction in silica 
exposure.
Aggregate ``Key'' and ``Secondary'' Labor Costs for Representative 
Projects
    To estimate aggregate labor costs or value for each equipment 
category, OSHA first matched OES occupational classifications with the 
labor requirements for each equipment category (e.g., hole drillers 
using hand-held or stand-mounted drills). These matching occupations 
are shown in Table V-37 of the FEA. In order to estimate the percentage 
of time during each work day that workers spend on activities using 
equipment in the relevant categories, OSHA designated some occupations 
as ``key'' and others as ``secondary.'' The key field in Table V-37 is 
set to ``1'', if a key occupation and to ``0'' if a secondary one. Even 
those employees who are engaged in tasks on Table 1 typically spend 
only a portion of their workdays engaged in silica-generating tasks, so 
the distinction between ``key'' and ``secondary'' is needed in order to 
estimate the amount of time workers participate in silica-generating 
tasks. In the preliminary and final cost analyses, OSHA applied ERG's 
occupation designation, as explained in greater detail below. OSHA 
requested comment on the designations of ``key'' and ``secondary'' 
designations in the PEA, but did not receive any comments challenging 
those designations.
    ``Key'' occupations refer to the worker or workers on each crew who 
perform the principal silica-generating activity using the equipment in 
each equipment category. For each equipment category, ERG estimated the 
overall percentage of time that workers in key occupations devote to 
the activity.
    Other ``secondary'' crew members (e.g., first-line supervisors/
managers and construction laborers) were estimated in terms of their 
ratio to the number of key workers required for given task areas. The 
secondary crew ratios range from 0 percent (no one in a secondary 
occupation engaged in silica-generating tasks) to 300 percent (three 
times the number of secondary occupation workers, in relation to the 
number of key workers, exposed to silica-generating tasks). As noted 
above, OSHA used these percentages and ratios to estimate (on an annual 
basis) the amount of time these employees are using relevant equipment 
to engage in work that causes silica exposures. The estimate of the 
percentage of time performing the silica-generating activity can be 
viewed in terms of the full-time-equivalent (FTE) employees engaged in 
work that utilizes equipment in each equipment category. These 
estimates and the corresponding ratios for secondary workers are shown 
in Table V-37 of the FEA.
    For the key occupations, OSHA was able to obtain some data with 
which to estimate the proportion of time workers perform activities 
using silica-generating equipment. For the secondary occupations, such 
estimates were generally not possible. Thus, the participation of 
secondary occupations in silica-generating activities was defined based 
on their relationship to the key occupations. This participation is 
defined by their presence in the job crews, as shown in Table V-30 of 
the FEA. To illustrate the need for this approach, consider the 
difficulty in predicting how often construction foremen of all types 
are present during activities where silica-generating equipment is 
used. BLS data, for example, provide only a total number of foremen, 
but no information about how they might spend their time. It is 
reasonable to forecast, however, using the job-crew definitions, that 
foremen will be present in some proportion to the number of workers in 
key occupations using jackhammers and other powered handheld chipping 
tools, rock and concrete drillers, and other silica-generating 
equipment. OSHA presented these data in the PEA and requested comments, 
but did not receive any on this aspect of the analysis. Therefore, OSHA 
is retaining its estimates from the PEA, except as noted.
    For some activities, the crew size and composition vary among the 
jobs defined in the equipment category. In those cases, OSHA used ERG 
determinations as to the most representative crew composition and used 
that crew model to define the ratio

[[Page 16506]]

of secondary to key occupations (ERG, 2007a, Document ID 1709).
    The estimates of the number of FTE employees engaged in activities 
using silica-generating equipment are one of many factors that 
influence the final cost estimates. There are few data, however, on the 
breakdown of time spent by construction workers in various activities. 
The following discussion presents the basis for the time-on-task 
estimates for the key occupations as included in the PEA and the FEA 
(except where noted). OSHA presented most of these estimates for public 
comment in the PEA but did not receive any comments challenging them.
Rock and Concrete Drillers
    A review of NIOSH reports covering rock and concrete drillers 
showed that over 75 percent of driller time was spent on actual 
drilling (NIOSH 1992a, Document ID 0911, NIOSH 1992b, Document ID 0910, 
NIOSH 1995, Document ID 0907) and is supported by updated data in 
NIOSH, 1999b (Document ID 0220). Therefore, for the PEA and FEA, OSHA 
used 75 percent as the best indication of the time spent using dust-
generating equipment for workers in this category.
Tuckpointers and Grinders
    Grinding and tuckpointing are only two of the numerous jobs 
performed by brickmasons, cement masons, and their helpers. Workers in 
those trades are much more frequently performing bricklaying, cement 
work, and masonry construction. Where tuckpointers and grinders are 
being used, a review of the OSHA Special Emphasis Program reports 
revealed that the time spent using tuckpointers and grinders varied 
widely (see the technological feasibility analysis for this activity in 
Chapter IV of the FEA). In both the PEA and in the FEA, OSHA used ERG's 
estimate that 2.5 percent of the time for workers in each of the 
applicable occupations would be spent on using this equipment.
Heavy Equipment Operators and Ground Crew Laborers
    For the final rule, heavy equipment operators and ground crew 
laborers were split into two categories in Table 1 based on how the 
heavy equipment and utility vehicles are being used, which reflects 
distinctions added in the final rule. This equipment is considered to 
either be used a) to abrade or fracture silica-containing materials 
(e.g., hoe-ramming, rock ripping) or used during the demolition of 
concrete or masonry structures; or b) for tasks such as grading and 
excavating but not including: demolition of concrete or masonry 
structures or abrading or fracturing silica-containing materials.
    ERG estimated that workers using heavy equipment to abrade or 
fracture silica-containing materials or for demolition devoted only 2.5 
percent of their time, on an FTE-equivalent basis, to doing this work.
    Key workers in the companion group using heavy equipment for 
grading and excavating often spend the bulk of their work shift on the 
equipment itself, engaged in construction work. OSHA Inspection Reports 
and other documentation consistently show that heavy equipment 
operators perform their tasks for more than 7 hours per shift (OSHA SEP 
Inspection Reports 122212079, 116179359; Greenspan, et al., 1995; NIOSH 
HETA 93-0696-2395, 1999; NIOSH, 1999b; NIOSH ECTB 233-120, 1999c.).\43\ 
Nevertheless, the heavy equipment operator occupational category also 
includes operators of such equipment as pile drivers, cranes, and air 
compressors that are not generally associated with silica dust 
generation. For the PEA, OSHA used ERG's estimate of 75 percent for 
operating engineers and 50 percent for excavating and loading machine 
and dragline operators in this category to estimate the number of heavy 
equipment operators performing silica-generating activities. OSHA did 
not receive any comment on these estimates and therefore has retained 
their substance for the FEA.
---------------------------------------------------------------------------

    \43\ Document ID 0133, 0192, 0716, 0220, and 0266, respectively.
---------------------------------------------------------------------------

Hole Drilling Using Handheld or Stand-Mounted Drills
    While many workers might occasionally be assigned to drill holes in 
concrete, this equipment category represents a very small part of the 
activities of the occupational groups performing this work. ERG judged 
that carpenters, electricians, plumbers, sheet metal workers, and 
helpers (construction laborers) spend one percent of their time 
drilling holes in silica-containing materials in the affected 
industries. OSHA presented this estimate in the PEA and did not receive 
comment or alternate estimates and has therefore retained the estimate 
for the FEA.
Jackhammers and Other Powered Handheld Chipping Tools
    OSHA estimated in the PEA that in the key occupation of 
construction laborers, relatively few use equipment in this category. 
In developing the estimate of time spent using equipment in this 
category for the PEA, ERG examined a snapshot of construction 
activities from the BLS publication, Injuries to Construction Laborers 
(BLS, 1986, Document ID 0559). That source presents a survey of injured 
construction workers and includes questions about their activities at 
the time they were injured. The survey indicated that 3 percent of 
construction workers were using jackhammers at the time they were 
injured. ERG judged that, while the survey was not intended to 
characterize typical construction activities, and a survey of injured 
workers introduces considerable potential bias into the observations, 
this estimate was useful as an observation of representative 
construction activities. ERG also judged that, because jackhammers are 
heavier, more cumbersome, and more powerful than much construction 
equipment, workers are probably injured more frequently while using 
jackhammers, on average, than when using all other construction 
equipment. Thus, the 3 percent figure is likely to be an upper bound of 
the amount of time spent using jackhammers and other powered handheld 
chipping tools. In the absence of other data, OSHA used ERG's estimate 
that 3 percent of laborers are using this equipment for the PEA. The 
Agency received no additional data or comment on this estimate and has 
therefore retained this estimate for the FEA.
Masonry and Concrete Cutters Using Portable Saws--I
    The key occupations using portable saws to cut masonry and 
concrete, namely brickmasons, blockmasons, stonemasons, and their 
helpers, spend, on average, a small share of their time cutting these 
materials with portable saws. In Table 1, OSHA notes three types of 
portable saws: (1) Hand-held saws, (2) walk-behind saws, and (3) 
drivable saws. Each of those is encompassed in this analysis, although 
small-diameter handheld saws are addressed separately. According to 
OSHA and NIOSH reports, the workers in these occupations perform 
multiple masonry activities and might engage in cutting for only a 
small portion of their shift (OSHA SEP Inspection Report 300646510; 
NIOSH, 1999a) (Document ID 0084). Another glimpse of this activity can 
be gleaned from the BLS injury report for construction laborers, where 
3 percent of workers were injured while breaking up or cutting 
concrete, asphalt, brick, rocks, etc. For each of the applicable 
occupations, OSHA estimated in the PEA that 10 percent of the workers' 
time would be spent using

[[Page 16507]]

the equipment in this category. The Agency received no comment on this 
estimate and has therefore retained this estimate for the FEA.
Masonry and Concrete Cutters Using Portable Saws--II--Small Diameter 
Saws for Cutting Fiber-Cement Board
    The task of using handheld power saws for cutting fiber-cement 
board (with blade diameter of 8 inches or less) was separated out in 
Table 1 in the final rule to recognize portable saws used for cutting 
cement fiberboard or cement fibersiding as a potential source of 
silica-containing dust. OSHA judged that portable saws would be used by 
carpenters or their helpers to cut fiber-cement board and that, on 
average, they would spend 2.5 percent of their time using equipment in 
this category to cut the referenced materials.
Masonry Cutters Using Stationary Saws
    As noted earlier, OSHA and NIOSH surveillance publications report 
that saw operators perform multiple masonry cutting activities and 
might engage in cutting silica-containing materials for only a small 
portion of their shift (OSHA SEP Inspection Report 300646510; NIOSH, 
1999a). For the PEA, OSHA used ERG's estimate that workers in mason 
occupations spend 10 percent of their time cutting silica-containing 
materials with stationary saws. The Agency received no comment on this 
estimate and has therefore retained this estimate for the FEA.
Millers Using Portable or Mobile Machines
    In the PEA, ERG identified two key occupation groups where millers 
are using portable or mobile machines: (1) Cement masons and (2) 
paving, surfacing, and tamping equipment operators. In response to 
comments (see Document ID 3585, Tr. 3036; 4220, p. 9; 3756, Attachment 
1), for the FEA, OSHA added a third key occupation group: Terrazzo 
workers and finishers. Milling using this equipment represents a small 
share of the overall job duties of these applicable key occupations: In 
the PEA OSHA judged that 5 percent of all work for the first two 
occupation groups is spent using this equipment, and OSHA is retaining 
that estimate in the FEA because there were no comments challenging 
that estimate. OSHA estimates that terrazzo workers use the equipment 
about half as much as the other two occupation groups, so OSHA 
estimates that 2.5 percent of all work time spent by terrazzo workers 
and finishers will be spent using this equipment.
Rock Crushing Machine Operators and Tenders
    According to information collected from ERG communication and OSHA 
SEP inspection reports, rock crushing machine operators spend most, if 
not all, of their shifts at and around the rock crushing process 
(Polhemus, 2000, Document ID 0958; Haney, 2001, Document ID 0721; OSHA 
SEP Inspection Report 2116507, Document ID 0186; OSHA SEP Inspection 
Report 300441862, Document ID 0030). OSHA estimated in the PEA that 
this occupational group spends 75 percent of its time using rock 
crushing machines and did not receive any comment on the estimate. OSHA 
has retained this estimate for the FEA.
Tunnel Boring
    Underground workers perform both tunnel work and other types of 
construction work. The majority of these underground tasks still fall 
under Table 1 and have been accounted for elsewhere in the appropriate 
construction task analysis. However, a small amount of silica-
generating underground construction work outside the scope of Table 1, 
primarily in tunnel boring, is expected to occur. The cost of 
engineering controls for this activity (to comply with the new PEL) is 
presented after the total engineering control costs to comply with 
Table 1 are presented.
SBREFA Panel Comments on Key and Secondary Occupations
    As stated in the comments during the Silica SBREFA process, one 
SBREFA commenter was ``unable to reconcile ERG's statement that `the 
amount of time . . . grinders and tuck-pointers perform grinding ranges 
widely, from about 1 hour per shift up to a full 8-hour shift (or 
longer)' [see the discussion on technological feasibility in Chapter IV 
of the FEA] with the 2.5% estimate in Table 4-8 [in the ERG report 
(2007a); Table V-26 in the PEA]'' (Document ID 0004; 1709). The 
commenter also asserted that masonry cutters use stationary saws 
approximately 20 to 30 percent of their working time (rather than 10 
percent), and that masonry cutters use portable saws approximately 5 
percent of their working time (rather than 10 percent) (Document ID 
0004).
    In response, OSHA reiterated in the PEA that Table V-26 of the PEA 
showed the estimates of the full-time-equivalent number of workers in 
key and secondary occupations using equipment to perform silica-
generating tasks. These occupations are taken from the BLS Occupational 
Employment Survey classification system and are much broader than the 
``masonry cutter'' category referred to by the commenter, implying a 
lower percentage of time devoted to tasks involving masonry cutting.
    OSHA did not receive further comment on this explanation. 
Therefore, OSHA has not changed these estimates in the FEA. For each 
occupation the estimates in Table V-37 of the FEA are meant to reflect 
the typical or average amount of a worker's time (over a year) devoted 
to the listed tasks.
FTE At-Risk Employment by Task Category
    Tables V-38a and V-38b of the FEA provide estimates, by occupation, 
of the full-time-equivalent (FTE) number of key and secondary workers, 
respectively, for each task category, using the percentages and ratios 
from Table V-37 of the FEA. These tables are relatively direct 
compilations from previous tables with adjustments needed, in a few 
cases, to assure that the industry-specific FTE occupational totals did 
not exceed the total occupational employment for any industry.
    Table V-39 of the FEA shows the corresponding estimates by NAICS 
code for the construction industry.
    OSHA distributed FTE at-risk workers across NAICS codes according 
to the combination of task categories and occupational (key and 
secondary) categories (from BLS, 2012, Document ID 1560) derived and 
updated by ERG for each industry group (ERG, 2007a, Document ID 1709).
    Overall, a full-time equivalent of 374,003 workers is estimated to 
use equipment to perform work on silica-containing materials in 
construction, ranging from 1,135 FTEs for rock crushing machine 
operators and tenders to 198,585 FTEs for heavy equipment operators and 
ground crew laborers (grading and excavating).
Total At-Risk Employment
    In the PEA, OSHA used a relatively crude approach to convert the 
estimated number of FTE affected construction workers to the number at-
risk construction workers. There, OSHA used a multiplier of 2 or 5, 
depending on the industry, to convert the number of FTEs to the number 
of at-risk workers (in Table V-37 of the PEA).
    OSHA received several comments regarding the analysis used in the 
PEA as being too simplistic. Joseph Liss challenged OSHA's methodology:

    Even though OSHA estimates the number of workers needing 
training for silica exposure under the proposed rule by

[[Page 16508]]

multiplying full-time equivalents by a factor of either 2 or 5, 
depending upon the sub-industry, the multiplicative factor for 
training purposes is likely to be much higher. For example, while 
paving, surfacing, and tamping operators spend a total of only 5% of 
their time on tasks exposed to silica, as estimated by ERG, it is 
not unlikely that many of the 51,857 workers in that industry sub-
group will do silica-exposed work at some point, and, thus, require 
training. There are 823,737 construction laborers, and ERG estimated 
that 3% of their time is spent on silica-exposed work, but the 
severe turnover in that industry means firms may need to train many 
of those workers in silica safety procedures and health effects. 
OSHA estimates the nation's 575,000 residential construction workers 
spend 5% of their time on construction work and uses a 
multiplicative factor of two, thus assuming that only 10% of those 
workers require training and exposure monitoring. Costs may increase 
if the number of workers exposed increases, since OSHA requires 
training for all newly hired workers as well as all initial training 
for all workers exposed to silica (citations omitted) (Document ID 
1950, p. 9).

    Additionally, the Construction Industry Safety Coalition (CISC) 
submitted calculations to arrive at their own results of at-risk 
workers. They note:

    These percentages represent our quick judgement across both the 
key occupations and the secondary occupations that OSHA identifies 
as participating in the crew when the at-risk task is performed. If 
we had more time, we would like to make this judgement more 
carefully (Document ID 4032, Tab 6).

    For the FEA, in response to comments, OSHA refined its process, as 
described below, to allow for a more nuanced approach to estimating the 
number of affected workers. As a result of this revised approach, the 
ratio of the estimated number of at-risk construction workers to the 
estimated number of FTE-affected construction workers increased from 
approximately three to one in the PEA to over five to one in the FEA. 
OSHA first assigned each of the affected NAICS construction industries 
to one of four subsectors in order to account for likely differences 
among specific industries with respect to the frequency with which 
silica-generating equipment is used. These subsectors are shown in 
Table V-40a of the FEA. Note that non-construction industries doing 
construction work--state and local governments and electric utilities--
are included in Subsector 3.
    Second, because at-risk workers do not necessarily specialize in 
jobs that use equipment that generates silica-containing dust, ERG 
independently estimated the number of ``affected'' workers based on 
judgments of the share of workers in each occupation that would likely 
ever perform these tasks. These judgments were also made on a 
subsector-by-subsector basis. In most cases, costs for program 
requirements (but not for engineering controls) are based on the 
numbers of affected workers performing each task in a given industry. 
The estimated share of affected workers for the key occupations, taking 
into account the specific construction subsector and task, is shown in 
Table V-40b of the FEA.
    Using the FTE rates, secondary ratios, and affected rate parameters 
displayed in Table V-37 of the FEA, OSHA calculated, in Table V-39 of 
the FEA, that there are an estimated 374,003 FTEs affected by the rule. 
Table V-41 of the FEA converts these FTEs to 2.02 million affected 
construction workers disaggregated by occupation based on 2012 County 
Business Pattern (CBP) total employment of 2.93 million in affected 
occupations in construction industries. Thus, as shown in Table V-41 of 
the FEA, about 68.9 percent of construction workers in affected 
occupations will be affected by the final rule. Table V-42 of the FEA 
shows the same estimated number of affected workers, but disaggregated 
by NAICS industries and equipment category. There are an estimated 
13.45 million workers total in the affected industries, meaning that 
about 15 percent of the workers in these industries are affected by the 
final rule. That percentage is misleading, however, because almost 7.7 
million of total employment in affected industries (almost 60 percent) 
are employed in state and local governments, of which only 2 percent 
are affected by the final rule. When these public workers are removed, 
approximately 32 percent of the construction workers in affected 
private industries are affected by the final rule.
    All of the above statistics do not include the estimated 11,640 at-
risk abrasive blasters working in construction industries. Also, 
because some occupations are associated with the use of more than one 
equipment category, the ``affected'' totals are constrained to be less 
than or equal to the industry total for each at-risk occupation.
Labor Cost and Total Value of Work Performed Using Silica Exposure-
Generating Equipment
    To derive labor costs and project value for construction work done 
using the specified equipment where occupational exposure to silica is 
found, OSHA multiplied the mean hourly wage, as reported by OES (BLS, 
2012, Document ID 1560), for each affected occupation within each 
affected industry, by 2,000 hours. Then, to derive the total value of 
annual wages expended for work done using specified equipment to 
perform silica exposure-generating activities, OSHA multiplied that 
product by the number of affected full-time-equivalent employees. These 
estimates were then inflated to adjust for fringe benefits. These 
loaded-wage costs, totaled by industry and equipment category, are 
summarized in Table V-43 of the FEA as the annual labor value (or labor 
cost) of silica-generating projects. Overall, OSHA estimated the labor 
value of all silica-generating construction work performed with the 
specified equipment to be $21.8 billion annually.
    OSHA then converted the labor values for each industry and task 
category from Table V-43 of the FEA to the total project value by 
dividing by the labor share of project costs. This conversion is 
possible because the labor share for each task category equals the 
labor value divided by project value, so dividing the labor value by 
the labor share generates an estimate of project value. The 
corresponding estimates of total project value for each industry and 
equipment category are shown in Table V-44 of the FEA. Overall, OSHA 
estimated the value of silica-generating construction work performed 
with the specified equipment at $41.2 billion. The values for specific 
equipment categories ranged from $136.2 million for rock crushing 
machine operators and tenders to $28.0 billion for heavy construction 
equipment operations-II.
    The value of work performed using the specified equipment was then 
summed by NAICS industry to derive the total value of at-risk projects, 
a base from which OSHA calculated control costs associated with 
compliance with Table 1 or the final PEL.
Aggregate Control Costs in Construction To Comply With Table 1 or the 
New PEL
    For the final rule, OSHA revised Table 1 to include separate 
engineering control and respirator requirements for tasks indoors or in 
enclosed areas (``indoor tasks'') to provide a means of exhaust as 
needed to minimize the accumulation of visible airborne dust. As a 
result, indoor tasks will have an additional cost to reflect use of 
control equipment (e.g., a fan or ``blower'') providing a means of 
exhaust as needed to minimize the accumulation of visible airborne 
dust. These additional indoor costs were included in Table V-34 of the 
FEA. However, to properly reflect these costs in the aggregate control 
costs in construction, OSHA had to add an additional methodological 
step. OSHA's Office of Technological Feasibility

[[Page 16509]]

helped to develop estimates of the distribution of silica-related work 
disaggregated by the type of control equipment used, the duration of 
the task, and the location of the task (i.e., indoors or outdoors). The 
resulting distribution of silica-related work, which is later used to 
weight costs by the percentage of tasks performed indoors or outdoors, 
is displayed in Table V-45 of the FEA.
    To derive estimates in Table V-46 of the FEA of aggregate 
incremental compliance costs to meet final Table 1, the total value of 
construction work using the specified equipment and requiring controls 
(in Table V-44 of the FEA) was multiplied by the percentage of 
incremental cost associated with the controls required for each 
equipment category (in Tables V-36a and V-36b of the FEA), weighted by 
the percentage of work using each type of equipment performed outdoors 
and indoors (in Table V-45 of the FEA), and reduced by the percentage 
of baseline compliance.
    As indicated in Table V-46 of the FEA, OSHA estimates that the 
incremental compliance costs for engineering controls (excluding tunnel 
boring and abrasive blasting) will total $386.4 million for 
construction work performed using the specified equipment affected by 
the final standard.
Control Costs for Construction Tasks Not Under Table 1
Abrasive Blasting
    In the PEA, OSHA estimated that some abrasive blasting crews were 
not currently using all feasible engineering controls and added costs 
for wet methods for them to achieve the proposed PEL. OSHA did not 
receive comments on the PEA estimates of engineering control costs for 
abrasive blasting crews and has retained the same methodology to 
estimate costs for the FEA.
    Consistent with what was done in the PEA, Table V-47a of the FEA 
presents the unit costs and analytical assumptions applied in OSHA's 
cost analysis of controlling silica exposures during abrasive blasting 
operations. As shown in the table, after accounting for the number of 
affected workers, crew size, daily output, blasting cost per square 
foot, number of blasting days per year, and the percentage of crews 
using sand, OSHA estimates that baseline annual costs for sand blasting 
total $126.7 million. As in the PEA, ERG estimated that the incremental 
cost for wet blasting is 30 percent of baseline costs and that 50 
percent of crews currently use wet methods. Therefore, the annual costs 
to comply with the final standard by using wet methods during sand 
blasting are expected to total $19.0 million, or $2,366 per worker for 
the approximately 8,033 workers exposed to silica dust.
    Distributing these annualized costs by industry, OSHA estimates 
that employers in NAICS 238200, Building Finishing Contractors, will 
incur compliance costs of $12.1 million annually, while firms in NAICS 
238900, Other Specialty Trade Contractors, will incur compliance costs 
of $6.9 million annually.
Tunnel Boring
    Tunnel boring is not included on Table 1 of the final rule. An 
employer engaged in tunnel boring must comply with the PEL of 50 [mu]g/
m\3\ specified in Sec.  1926.1153(d). Employers in tunnel boring must 
already comply with the ventilation and dust suppressant requirements 
in subpart S of Part 1926 (Underground construction), which would have 
allowed those employers to meet the previous PEL of 250 [mu]g/m\3\. 
Therefore, OSHA calculates the additional controls necessary to reduce 
exposures from the preceding PEL to the new PEL of 50 [mu]g/m\3\.
    In most cases, employers are able to reduce exposures to the 
preceding PEL by providing suction at the drill head, removing the dust 
as soon as it is generated. The technological feasibility chapter of 
the FEA demonstrates that employers can do so by extending the existing 
suction controls as the drill head progresses. There are limits on 
these extensions, however, and the amount of worker exposure can 
increase if the suction is not extended frequently enough to keep it at 
the drill head. This extension does not require additional machinery, 
but it is likely to require the employer to invest more labor time to 
extend the suction device more frequently to meet the new PEL than 
previously necessary to meet the preceding PEL. OSHA has estimated in 
Table V-47 of the FEA the control costs for tunnel boring using the 
same cost methodology applied in the PEA (see Tables V-21 and V-24 in 
the PEA) to calculate the incremental cost as a percentage of baseline 
control costs (0.013%). The rest of the calculations in Table V-47 
reflect 2012 data on the number of affected FTE tunnel workers and 2012 
hourly wage rates. The resulting estimate of annualized incremental 
control costs for tunnel boring is about 0.02 million.
    Table V-48 of the FEA adds the abrasive blasting and the tunnel 
boring control costs in construction to the control costs for Table 1 
tasks presented in Table V-46 of the FEA.
Adjustment for Self-Employed Workers on a Multi-Employer Worksite
    The OSH Act provides authority for OSHA to regulate employers for 
the protection of their employees. Because sole proprietors without 
employees, referred to as ``self-employed workers'' for the purposes of 
this discussion, are not ``employers'' under the Act, OSHA cannot 
require them to comply with the silica standard. On a multi-employer 
worksite, however, their silica activities could expose employees 
protected by the Act to respirable crystalline silica.
    Employers must still protect their employees from exposure to 
silica in accordance with the standard, whether it is generated by work 
performed by their own employees or by the work performed by a sole 
proprietor not regulated by the Act (see the summary and explanation of 
the written exposure control plan requirements in paragraph Sec.  
1926.1153(g)(1)(iv)). Under OSHA's multi-employer citation policy (CPL 
02-00-124), employers of workers who may be exposed to silica are 
considered ``exposing employers'' who have a duty to protect their 
employees, even from hazards they do not correct themselves. However, 
the controlling employer, the employer in overall charge of the 
worksite or project, also has a duty to exercise reasonable care to 
prevent and detect violations of the silica standard on the multi-
employer worksite. The silica standard does not limit the means by 
which either employer may fulfill this duty, and in many cases the 
issue may be resolved if the work schedule does not place the self-
employed worker in the same area of the worksite at the same time as 
employees, thereby avoiding the need for additional measures.
    As discussed in Chapter III of the FEA, CISC requested that the 
Agency account for the costs arising from self-employed workers 
separately based on the theory that self-employed workers will use the 
controls necessary to comply with Table 1 to reduce exposures to others 
when working on a multi-employer worksite where employees are present 
(Document ID 4217, p. 80). CISC identified several reasons why this 
might happen, including self-interested recognition of ``Table 1 
specifications as the safe way to perform their work''; demands by 
construction general contractors that anyone working on their site, 
whether self-employed or not, conform to regulatory requirements; and 
demands by nearby employers that their employees ``not suffer increased 
silica

[[Page 16510]]

exposures from inappropriate practices by self-employed workers.''
    While these are not costs that OSHA typically includes in its 
analysis, OSHA recognizes that Table 1 is unique among OSHA standards, 
and that it is possible that controlling employers on a multi-employer 
construction worksite may assume some costs of engineering controls--
either by providing the controls or by reimbursing the self-employed 
persons for the costs of the controls through increased fees--when they 
cannot resolve the issue through simple scheduling choices. Therefore, 
OSHA is estimating the additional cost of the engineering controls in 
that scenario.
    In order to estimate the number of self-employed persons in 
construction, CISC's contractor, Environomics, Inc., took the following 
approach:

    The U.S. Census Bureau, in Revised 2008 Nonemployer Statistics 
Reflecting 2009 Methodology Changes, provides information on the 
number of self-employed individuals (``nonemployers'') working in 
each of the 4-digit construction industries (total of 2.52 million 
self-employed construction workers), but no further information on 
the occupations of these self-employed workers. In order to estimate 
the number of self-employed workers in each of the various at-risk 
construction occupations that OSHA identified and that we added, we 
simply assumed that these 2.52 million ``nonemployers'' are 
distributed among occupations within each construction NAICS in the 
same proportion as employed workers are distributed among 
occupations within the NAICS (Document ID 4217, p. 80).

    Note that the Census data that Environomics used provides detail on 
self-employed persons by 4-digit NAICS construction industries but not 
by occupation. Hence, in the absence of occupational data, Environomics 
simply assumed that the number of self-employed persons by occupation 
was proportional to the number of employees by occupation--which 
implies that the ratio of the number of self-employed persons to 
employees was the same for each occupation. Using this database and 
approach, Environomics estimated that the ratio of self-employed 
persons to employees for all occupations affected by the rule was 40.1 
percent (1,811,009 self-employed relative to 4,519,889 employees). 
Based on the full-time-equivalent (FTE) number of workers--which, in 
OSHA's estimation methodology, determines the amount of engineering 
control equipment used--Environomics calculated that the ratio of FTE 
self-employed persons to FTE employees for all occupations affected by 
the rule was 35.7 percent.
    Having reviewed the Environomics self-employment analysis, OSHA has 
concluded that the occupation of the self-employed persons is a much 
more relevant factor for estimating costs than the 4-digit construction 
industry in which self-employed persons work. Therefore, for its 
analysis, OSHA has chosen to rely on data from the 2013 BLS Current 
Population Survey, with the goal of estimating the ratio of the number 
of self-employed persons to the number of employees by occupation. 
Table V-49 of the FEA presents data from the 2013 BLS Current 
Population Survey with the focus on the ratio of the self-employed to 
the non-self-employed (i.e., employees).\44\ Note that this table 
includes many occupations that do not involve silica exposure (e.g., 
boilermakers, paperhangers, glaziers) and others that are not covered 
by OSHA (e.g., mining machine operators; roof bolters, mining--covered 
by MSHA).
---------------------------------------------------------------------------

    \44\ The absolute number of self-employed and employed in 
construction by occupation from this survey is not, itself, relevant 
for this analysis. What matters is the ratio of self-employed to 
non-self employed in construction where the estimates of both types 
of workers are derived from a single source.
---------------------------------------------------------------------------

    Table V-50 of the FEA presents the same data as shown in Table V-49 
of the FEA, but restricted to just those occupations where OSHA 
estimated that workers are potentially exposed to hazardous levels of 
respirable crystalline silica. One thing that is immediately obvious in 
this table is the very wide variation from occupation to occupation in 
the ratio of the self-employed to the employed, with the ratio ranging 
from 0 percent to 47.53 percent. This wide variation is clearly 
incompatible with the assumption made by Environomics that the ratio of 
the number of self-employed to employees is the same for all 
occupations. Table V-50 of the FEA also shows that average ratio of 
self-employed to employees over all construction occupations involving 
silica exposure (when the ratio is allowed to vary by occupation) is 
22.82 percent when weighted by the number of employees (as compared to 
40.1 percent as estimated by Environomics).
    As noted above, in OSHA's methodology, the amount of engineering 
control equipment used is based on the FTE number of workers. In Table 
V-51 of the FEA, OSHA multiplied the FTE rate for each occupation (from 
Tables V-38a and V-38b of the FEA) by the number of self-employed 
workers and employees in that occupation (from Table V-48 of the FEA). 
As shown in Table V-51 of the FEA, there are an estimated 69,461 FTE 
self-employed workers in at-risk occupations, relative to the total of 
377,913 FTE employees in at-risk occupations. In other words, the 
number of at-risk FTE self-employed workers is 18.38 percent of the 
number of at-risk FTE employees (as compared to 35.7 percent as 
estimated by Environomics).
    The analysis of the number of self-employed persons conducted by 
Environomics stopped at this point. However, as OSHA explained in 
Chapter III of the FEA, self-employed workers are not required to 
comply with the final rule and are only likely to do so in two 
situations: (1) Where self-employed workers are generating silica dust 
while working in a multi-employer construction worksite such that their 
activities could expose the employees of others, and (2) where the host 
employer (or competent person) is unable to schedule the self-employed 
worker's activities or location so as to prevent the exposure or 
overexposure of other, covered workers. OSHA does not have data on the 
likelihood of either of these two conditions. OSHA judges that self-
employed workers work at multi-employer construction sites at the same 
times as others a minority of their worktime, and work even less 
frequently within the same area such that covered employees could be 
exposed. Nevertheless, OSHA is conservatively estimating here that they 
do so 50 percent of the time. OSHA also judges that the host contractor 
(with the assistance of the competent person) would be able to schedule 
the self-employed workers' activities or location so as to prevent the 
exposure or overexposure of other, covered workers a majority of the 
time. This makes sense because self-employed workers would often be 
used on multi-employer sites when they possess special skills not 
otherwise available onsite. Therefore, their work frequently could be 
performed at a different time or location from the other work. In any 
case, for costing purposes, OSHA is conservatively estimating that the 
work of self-employed persons cannot be isolated in time or space so as 
to prevent the exposure or overexposure of other, covered workers 50 
percent of the time that those self-employed workers are on the multi-
employer worksite.
    Based on these estimates, OSHA calculates that only 25 percent of 
the at-risk work of self-employed workers would meet the conditions in 
which a host or controlling employer would incur engineering control 
costs to mitigate the exposures to employees on the site. At the bottom 
of Table V-51 of the FEA, OSHA has accordingly reduced the number of 
FTE self-

[[Page 16511]]

employed workers using equipment to perform silica-dust-producing work 
relative to the number of FTE at-risk employees to 25 percent of the 
earlier estimate of 18.38 percent. OSHA therefore concludes that the 
number of FTE at-risk self-employed workers imposing costs on host 
employers is equal to 4.60 percent of the number of FTE at-risk 
employees. This result is shown at the bottom of Table V-51 of the FEA.
    Finally, in Table VII-13, OSHA increased the estimates of the 
control costs for work performed using the specified equipment in 
construction presented in Table V-48 of the FEA by 4.60 percent to 
include the engineering control costs that would be incurred by host or 
controlling employers to control the exposures caused by self-employed 
workers. This increases the annualized cost of engineering controls 
needed in construction to comply with the final rule from $405.5 
million to $423.4 million.

[[Page 16512]]

[GRAPHIC] [TIFF OMITTED] TR25MR16.053

2. Respiratory Protection
    OSHA's cost estimates assume that implementation of the recommended 
silica controls prevents workers in general industry and maritime from 
being exposed over the PEL in most cases. Specifically, based on its 
technological feasibility analysis, OSHA expects that the engineering 
controls are adequate to keep silica exposures at or below the PEL for 
an alternative PEL of 100 [mu]g/m\3\ (introduced for economic analysis 
purposes).\45\ For the new 50 [mu]g/m\3\ PEL, OSHA's feasibility 
analysis

[[Page 16513]]

suggests that the controls that employers use, either because of 
technical limitations or imperfect implementation, might not be 
adequate in all cases to ensure that worker exposures in all affected 
job categories are at or below 50 [mu]g/m\3\.
---------------------------------------------------------------------------

    \45\ As a result, OSHA expects that establishments in general 
industry do not currently use respirators to comply with the current 
OSHA PEL for quartz of approximately 100 [mu]g/m\3\.
---------------------------------------------------------------------------

    For the FEA, OSHA estimates that respirators will be required: (1) 
For all workers that the Agency's technological feasibility analysis 
has determined will require respirator use; and (2) for ten percent of 
the remaining workers currently exposed above 50 [mu]g/m\3\ at covered 
workplaces.
    This is a change in methodology from the PEA, where OSHA estimated 
the percentage of workers requiring respirators in an industry as 
either (1) or (2), whichever was larger. The Agency believes that the 
FEA formula, which results in higher estimates of respirator usage, is 
more accurate in that it reflects the combined effects of (1) and (2) 
whereas the earlier methodology did not. The number of workers that the 
FEA estimates will need respirators is presented in Table V-13 in the 
FEA.
    In the PEA, OSHA concluded that all maritime workers engaged in 
abrasive blasting were already required to use respirators under 
existing OSHA standards and, therefore, maritime establishments would 
incur no additional costs for maritime workers to use respirators as a 
result of this final rule. However, for the FEA, OSHA has determined 
from its earlier technological feasibility analysis that only abrasive 
blasting operators, but not abrasive blasting helpers, are already 
required to use respirators under existing OSHA standards. The Agency, 
therefore, has added respirator costs for abrasive blaster helpers in 
maritime (half of all the abrasive blaster workers) as a result of this 
final rule.
    For construction, employers whose workers are exposed to respirable 
silica above the proposed PEL were assumed to adopt the appropriate 
task-specific engineering controls and, where required, respirators 
prescribed in Table 1 and paragraph (g)(1) in the final standard. 
Respirator costs in the construction industry have been adjusted to 
take into account OSHA's estimate (consistent with the findings from 
the NIOSH Respiratory Survey, 2003, Document ID 1492) that 56 percent 
of establishments in the construction industry are already using 
respirators that would be in compliance with the final silica rule.
    OSHA used respirator cost information from a 2003 OSHA respirator 
study to estimate the annual cost of $367 (general industry) or $286 
(construction) for disposable filtering facepiece respirators, $520 
(general industry) or $409 (construction) for a half-mask, non-powered, 
air-purifying respirator and $644 (general industry) or $533 
(construction) per year (in 2012 dollars) for a full-face non-powered 
air-purifying respirator (ERG, 2003, Document ID 1612). These unit 
costs reflect the annualized cost of respirator use, including 
accessories (e.g., filters), training, fit testing, and cleaning where 
relevant.
    The PEA estimated that (with the exception of workers who are 
entering regulated areas) all workers in general industry and 
construction who need respirators with an assigned protection factor 
(APF) of 10 would use non-disposable, half-face respirators. The FEA 
estimates that in general industry half of the workers who need 
respirators will use half-face elastomeric respirators and half will 
use disposable N95 respirators. This is because, as clarified in the 
final rule, both disposable and non-disposable respirators are 
available with an APF of 10, and, with each type of respirator offering 
certain advantages, OSHA accordingly estimates that about half of the 
employees in general industry and maritime will prefer the ease of use 
of disposable respirators while the other half will prefer the 
durability of non-disposable respirators. For the construction sector, 
the FEA estimates that 10 percent of workers needing respirators will 
use elastomeric half-face respirators and 90 percent will use 
disposable N95 respirators. This is because very few workers in 
construction engage in tasks requiring respirator use full-time. Under 
those circumstances, disposable respirators are both more convenient to 
use and much less expensive than reusable respirators.
    In addition to bearing the costs associated with the provision of 
respirators, employers will incur a cost burden to establish respirator 
programs. OSHA projects that this expense will involve an initial 8 
hours for establishments with 500 or more employees and 4 hours for all 
other firms. After the first year, OSHA estimates that 20 percent of 
establishments would revise their respirator program every year, with 
the largest establishments (500 or more employees) expending 4 hours 
for program revision, and all other employers expending 2 hours for 
program revision. Consistent with the findings from the NIOSH 
Respiratory Survey (2003) (Document ID 1492), OSHA estimates that 56 
percent of establishments in the construction industry that would 
require respirators to achieve compliance with the final PEL already 
have a respirator program.\46\ OSHA further estimates that 50 percent 
of firms in general industry and all maritime firms that would require 
respirators to achieve compliance already have a respirator program.
---------------------------------------------------------------------------

    \46\ OSHA's derivation of the 56 percent current compliance rate 
in construction, in the context of the final silica rule, is 
described in Chapter V in the FEA.
---------------------------------------------------------------------------

3. Exposure Assessment
    OSHA developed separate cost estimates for (1) initial monitoring 
or any exposure monitoring at hydraulic fracturing sites and (2) 
scheduled monitoring at fixed sites (which excludes hydraulic 
fracturing). Costs under (2) were estimated to be lower because the 
exposure monitoring is expected to be of shorter duration (possibly 
obviating an overnight stay) and could be conducted by a lower-cost 
Industrial Hygienist (IH) or IH technician rather than by a CIH. Based 
on the comments received in the record, OSHA decided to significantly 
increase its estimate from $500 (in the PEA) to $2,500 for an IH 
consultant to perform initial exposure monitoring or to perform at 
sites that have not previously been well characterized. In the 
construction sector, the $2,500 cost estimate for IH services applies 
to all exposure monitoring since the worksite is not fixed and has not 
been previously characterized. OSHA estimates that the IH periodic 
exposure monitoring costs would be approximately $1,250, or half of the 
$2,500 estimate. These IH monitoring costs would cover 2, 6, and 8 
personal breathing zone (PBZ) samples per day for small, medium, and 
large establishments, respectively.
    For initial monitoring or any exposure monitoring at hydraulic 
fracturing sites, the total unit cost of an exposure sample is 
estimated to range from $487 to $1,425 (depending on establishment 
size). For periodic monitoring in general industry and maritime, 
excluding hydraulic fracturing sites, the total unit cost of an 
exposure sample is estimated to range from $328 to $796 (depending on 
establishment size).
    Tables V-14 and V-61 in the FEA shows the unit costs and associated 
assumptions used to estimate exposure assessment costs. Unit costs for 
exposure sampling include direct sampling costs, the costs of 
productivity losses, and recordkeeping costs, and, depending on 
establishment size, range from $328 to $1,421 per sample in general 
industry and maritime and from $488 to $1,425 per sample in 
construction.

[[Page 16514]]

    For costing purposes, based on OSHA (2016), OSHA estimated that 
there are four workers per work area. OSHA interpreted the initial 
exposure assessment in general industry and maritime as requiring 
first-year testing of at least one worker in each distinct job 
classification and work area who is, or may reasonably be expected to 
be, exposed to airborne concentrations of respirable crystalline silica 
at or above the action level.
    For periodic monitoring, the final standard provides employers an 
option of assessing employee exposures either under a performance 
option (paragraph (d)(2)) or a scheduled monitoring option (paragraph 
(d)(3)). For the performance option, the employer must assess the 8-
hour TWA exposure for each employee on the basis of any combination of 
air monitoring data or objective data sufficient to accurately 
characterize employee exposures to respirable crystalline silica. For 
the scheduled monitoring option (termed the ``periodic'' monitoring 
option in the proposal), the employer must perform initial monitoring 
to assess the 8-hour TWA exposure for each employee on the basis of one 
or more (PBZ) air samples that reflect the exposures of employees on 
each shift, for each job classification, in each work area. Where 
several employees perform the same job tasks on the same shift and in 
the same work area, the employer may sample a representative fraction 
of these employees in order to meet this requirement. In representative 
sampling, the employer must sample the employee(s) who are expected to 
have the highest exposure to respirable crystalline silica. Under the 
scheduled monitoring option, requirements for periodic monitoring 
depend on the results of initial monitoring. If the initial monitoring 
indicates that employee exposures are below the action level, no 
further monitoring is required. If the most recent exposure monitoring 
reveals employee exposures to be at or above the action level but at or 
below the PEL, the employer must repeat monitoring within six months of 
the most recent monitoring. If the most recent exposure monitoring 
reveals employee exposures to be above the PEL, the employer must 
repeat monitoring within three months of the most recent monitoring. 
OSHA used the fixed schedule option under the frequency-of-monitoring 
requirements to estimate, for costing purposes, that exposure 
monitoring will be conducted (a) twice a year where initial or 
subsequent exposure monitoring reveals that employee exposures are at 
or above the action level but at or below the PEL, and (b) four times a 
year where initial or subsequent exposure monitoring reveals that 
employee exposures are above the PEL.
    As required under paragraph (d)(4) of the final rule, employers 
must reassess exposures whenever a change in the production, process, 
control equipment, personnel, or work practices may reasonably be 
expected to result in new or additional exposures at or above the 
action level, or when the employer has any reason to believe that new 
or additional exposures at or above the action level have occurred. In 
response to comments, OSHA increased its estimate from 15 percent to 25 
percent of the share of workers whose initial exposure or subsequent 
monitoring was at or above the action level would undertake additional 
monitoring.
    Changes from the proposed to the final rule have resulted in a 
significant reduction in OSHA's estimate of the annual number of 
samples taken by construction employers. For the final rule, employers 
following Table 1 are not required to engage in initial or subsequent 
exposure monitoring for those construction workers engaged in tasks on 
Table 1. Therefore, OSHA only estimated scheduled semi-annual exposure 
monitoring (for expected exposures at or above the action level but at 
or below the PEL) and scheduled quarterly exposure monitoring costs 
(for expected exposures above the PEL) for those operations are not 
listed on Table 1. In addition, OSHA estimated that some small fraction 
of employers--1 percent--will choose to conduct initial sampling to 
investigate the possibility that exposures are so low (below the action 
level) that Table 1 need not be followed.
    A more detailed description of unit costs, other unit parameters, 
and methodological assumptions for exposure assessments is presented in 
Chapter V of the FEA.
4. Medical Surveillance
    Paragraph (i) of the final standard requires the employer to make 
medical surveillance available for each employee occupationally exposed 
to respirable crystalline silica at or above the action level of 25 
[mu]g/m\3\ for 30 days or more per year. ERG (2013) assembled 
information on representative unit costs for initial and periodic 
medical surveillance (Document ID 1712). Separate costs were estimated 
for current employees and for new hires as a function of the employment 
size (i.e., 1-19, 20-499, or 500+ employees) of affected 
establishments. Table V-16 in the FEA presents ERG's unit cost data and 
modeling assumptions used by OSHA to estimate medical surveillance 
costs.
    In accordance with paragraph (i)(2) of the final standard, the 
initial medical examination will consist of (1) a medical and work 
history, (2) a physical examination with special emphasis on the 
respiratory system, (3) a chest x-ray interpreted and classified 
according to the International Labour Office (ILO) International 
Classification of Radiographs of Pneumoconiosis by a NIOSH-certified B 
Reader, (4) a pulmonary function test administered by a spirometry 
technician with a current certificate from a NIOSH-approved course, (5) 
testing for latent tuberculosis (TB) infection, and (6) any other tests 
deemed appropriate by the PLHCP. In accordance with paragraph (i)(3) of 
the final standard, the contents of the periodic medical examinations 
are the same as those for the initial examination, with the exception 
that testing for latent tuberculosis infection is not required.
    As shown in Table V-16 in the FEA, the estimated unit cost of the 
initial health screening for current employees in general industry and 
maritime ranges from approximately $415 to $435 and includes direct 
medical costs, the opportunity cost of worker time (i.e., lost work 
time, evaluated at the worker's 2012 hourly wage, including fringe 
benefits) for offsite travel and for the initial health screening 
itself, and recordkeeping costs. The variation in the unit cost of the 
initial health screening is due entirely to differences in the 
percentage of workers expected to travel offsite for the health 
screening. In OSHA's experience, the larger the establishment the more 
likely it is that the selected PLHCP would provide the health screening 
services at the establishment's worksite. OSHA estimates that 20 
percent of establishments with fewer than 20 employees, 75 percent of 
establishments with 20-499 employees, and 100 percent of establishments 
with 500 or more employees would have the initial health screening for 
current employees conducted onsite.
    The unit cost components of the initial health screening for new 
hires in general industry and maritime are identical to those for 
existing employees with the exception that the percentage of workers 
expected to travel offsite for the health screening would be somewhat 
larger (due to fewer workers being screened annually, in the case of 
new hires, and therefore yielding fewer economies of onsite screening). 
OSHA estimates that 10 percent of establishments with fewer than 20

[[Page 16515]]

employees, 50 percent of establishments with 20-499 employees, and 90 
percent of establishments with 500 or more employees would have the 
initial health screening for new hires conducted onsite. As shown in 
Table V-16 in the FEA, the estimated unit cost of the initial health 
screening for new hires in general industry and maritime ranges from 
approximately $417 to $437.
    The unit costs of medical surveillance in construction were derived 
using identical methods. As shown in Table V-63 of the FEA, the 
estimated unit costs of the initial health screening for current 
employees in construction range from approximately $429 to $467; the 
estimated unit costs of the initial health screening for new hires in 
construction range from $433 to $471.
    In accordance with paragraph (h)(2) of the final standard, the 
initial medical examination will consist of (1) a medical and work 
history, (2) a physical examination with special emphasis on the 
respiratory system, (3) a chest x-ray interpreted and classified 
according to the International Labour Office (ILO) International 
Classification of Radiographs of Pneumoconioses by a NIOSH-certified B 
Reader, (4) a pulmonary function test administered by a spirometry 
technician with a current certificate from a NIOSH approved course, (5) 
testing for latent tuberculosis (TB) infection, and (6) any other tests 
deemed appropriate by the physician or licensed health care 
professional (PLHCP). In accordance with paragraph (h)(3) of the final 
standard, the contents of the periodic medical examinations are the 
same as those for the initial examination, with the exception that 
testing for latent tuberculosis infection is not required.
    The estimated unit cost of periodic health screening also includes 
direct medical costs, the opportunity cost of worker time, and 
recordkeeping costs. As shown in Table V-16 in the FEA, these triennial 
unit costs in general industry and maritime vary from $415 to $435. For 
construction, as shown in Table V-63 in the FEA, the triennial unit 
costs for periodic health screening vary from roughly $429 to $467. The 
variation in the unit cost (with or without the chest x-ray and 
pulmonary function test) is due entirely to differences in the 
percentage of workers expected to travel offsite for the periodic 
health screening. OSHA estimated that the share of workers traveling 
offsite, as a function of establishment size, would be the same for the 
periodic health screening as for the initial health screening for 
existing employees.
    OSHA estimated a turnover rate of 75 percent in general industry 
and maritime and 40 percent in construction, based on estimates of the 
separations rate (layoffs, quits, and retirements) provided by the 
Bureau of Labor Statistics (BLS, 2012). However, not all new hires 
would require initial medical testing. As specified in paragraph (h)(2) 
of the final rule, employees who had received a medical examination 
that meets the requirements of this section within the previous three 
years would be exempt from undergoing a second ``initial'' medical 
examination. OSHA estimates that 25 percent of new hires in general 
industry and maritime and 60 percent of new hires in construction would 
be exempt from the initial medical examination.
    Although OSHA believes that some affected establishments in 
construction currently provide some medical testing to their silica-
exposed employees, there was significant testimony in the record that 
many employers would at least have to make changes to their existing 
practices in order to comply with the new standard. Therefore, for 
costing purposes, the Agency assumed no current compliance with the 
health screening requirements of the rule.
    OSHA requested information from interested parties on the current 
levels and the comprehensiveness of health screening in general 
industry, maritime, and construction. Although testimony in the record 
indicated that current medical surveillance programs exist to a limited 
extent among affected employers (see Chapter V, Costs of Compliance) 
for costing purposes for the rule, OSHA has conservatively assumed no 
current compliance with the health screening requirements.
    Finally, OSHA estimated the unit cost of a medical examination by a 
pulmonary specialist for those employees found to have signs or 
symptoms of silica-related disease or are otherwise referred by the 
PLHCP. OSHA estimates that a medical examination by a pulmonary 
specialist costs approximately $335 for workers in general industry and 
maritime and $364 for workers in construction. This cost includes 
direct medical costs, the opportunity cost of worker time, and 
recordkeeping costs. In all cases, OSHA anticipates that the worker 
will travel offsite to receive the medical examination by a pulmonary 
specialist (see Chapter V in the FEA for a full discussion of OSHA's 
analysis of medical surveillance costs under the final standard).
5. Familiarization Costs and Costs of Communication of Silica Hazards 
to Employees
    OSHA did not estimate any employer familiarization costs in the PEA 
in support of the proposed rule. OSHA's rationale for not including 
familiarization costs in the PEA was that there was already an existing 
silica standard in place and, therefore, the Agency expected that any 
familiarization costs for a revised silica standard would be 
negligible.
    However, several commenters on the proposed rule argued that 
employers will need to spend time to become familiar with the 
requirements of the final rule; that the employer time spent is the 
direct result of the final rule itself; and, therefore, that OSHA 
should include employer familiarization costs as part of the costs of 
the final rule.
    OSHA found the comments in support of including some 
familiarization costs persuasive and the Agency has now concluded that 
employers will need to spend some time to understand the ancillary 
provisions and the other new and revised components of the final rule 
and to determine what actions they must take in order to comply. OSHA 
estimated that 8 hours would be spent on familiarization in its 2012 
update to the Hazard Communication Standard (see 77 FR 17637-17638 
(March 26, 2012)) and believes that this is a reasonable estimate of 
familiarization time for a typical firm for this final silica rule.
    For the silica rule OSHA used the number of employees as a proxy 
for the level of familiarization that would be needed. Accordingly, 
OSHA has reduced the average of 8 hours of familiarization time for 
establishments with fewer employees and increased it significantly for 
establishments with a larger number of employees: 4 hours per covered 
employer with fewer than 20 employees; 8 hours per covered employer 
with 20 to 499 employees; and 40 hours per covered employer with 500 or 
more employees. These estimates represent average familiarization 
times; it is expected that some establishments will spend less time on 
familiarization than estimated here (e.g.,, if worker exposure never 
meets or exceeds the action level) and some will spend more time on 
familiarization than estimated here. The annualized costs per 
establishment range from $19 to $189 for establishments in general 
industry and maritime and from $21 to $207 for establishments in 
construction.
    The final standard requires two forms of hazard communication to 
employees: Paragraph (j)(1) notes that employers

[[Page 16516]]

must include respirable crystalline silica in their existing hazard 
communication programs required by the hazard communication standard 
(HCS) (29 CFR 1910.1200), and paragraph (j)(3) requires that employers 
must provide employees with specific information and training. As 
specified in paragraph (j)(3)(i) of the final rule and the HCS, 
training is required for all employees in general industry and maritime 
are covered by the standard. This requirement applies to newly hired 
workers who would require training before starting work, workers who 
change jobs within their current workplace or are assigned new tasks or 
exposure protection, and any covered worker an employer believes needs 
additional training. Thus OSHA has estimated a one-time training cost 
for existing employees as well as recurring training costs to account 
for new hires.
    OSHA estimated separate costs for initial training of current 
employees and for training new hires. Given that new-hire training 
might need to be performed frequently during the year, OSHA estimated a 
smaller class size for new hires. OSHA anticipates that training, in 
accordance with the requirements of the final rule, will be conducted 
by in-house safety or supervisory staff with the use of training 
modules or videos and will last, on average, one hour. OSHA judged that 
establishments could purchase sufficient training materials at an 
average cost of $2.10 per worker, encompassing the cost of handouts, 
video presentations, and training manuals and exercises. Included in 
the cost estimates for training are the value of worker and trainer 
time as measured by 2012 hourly wage rates (to include fringe 
benefits). OSHA also developed estimates of average class sizes as a 
function of establishment size. For initial training, OSHA estimated an 
average class size of 5 workers for establishments with fewer than 20 
employees, 10 workers for establishments with 20 to 499 employees, and 
20 workers for establishments with 500 or more employees. For new hire 
training, OSHA estimated an average class size of 2 workers for 
establishments with fewer than 20 employees, 5 workers for 
establishments with 20 to 499 employees, and 10 workers for 
establishments with 500 or more employees.
    The unit costs of training are presented in Tables V-22 (for 
general industry/maritime) and V-69 (for construction) in the FEA. 
Based on ERG's work, OSHA estimated the annualized cost (annualized 
over 10 years) of initial training per current employee at between 
$3.39 and $4.10 and the annual cost of new-hire training at between 
$30.90 and $47.05 per employee in general industry and maritime, 
depending on establishment size. For construction, OSHA estimated the 
annualized cost of initial training per employee at between $4.21 and 
$4.99 and the annual cost of new hire training at between $38.14 and 
$55.76 per employee, depending on establishment size.
    OSHA recognizes that many affected establishments currently provide 
training on the hazards of respirable crystalline silica in the 
workplace. In the PEA OSHA estimated that 50 percent of affected 
establishments already provide such training. However, some of the 
training specified in the final rule requires that workers be familiar 
with the training and medical surveillance provisions in the rule.
    The Agency reviewed its baseline training estimates in light of 
comments in the record decided to take a more conservative approach to 
estimating current compliance with the training provisions in the final 
rule. Therefore, for the FEA, OSHA assumed no baseline respirable 
crystalline silica training (other than that already required under the 
HCS) and that a full hour of training, on average, will be required for 
all covered workers. This removal of baseline respirable crystalline 
silica training in estimating training costs has the effect, by itself, 
of increasing the effective training costs in the FEA relative to the 
PEA by 33 percent (from an average training time, per employee, of 45 
minutes to 60 minutes). OSHA recognizes that this change may lead to an 
overestimation of training costs for some employers.
6. Regulated Areas
    Paragraph (e)(1) of the final standard requires employers in 
general industry and maritime to establish a regulated area wherever an 
employee's exposure to airborne concentrations of respirable 
crystalline silica is, or can reasonably be expected to be, in excess 
of the PEL. Paragraph (e)(2)(i) requires employers to demarcate 
regulated areas from the rest of the workplace in a manner that 
minimizes the number of employees exposed to respirable crystalline 
silica within the regulated area. Paragraph (e)(2)(ii) requires 
employers to post signs at all entrances to regulated areas bear the 
legend specified in paragraph (j)(2) of the standard. Under paragraph 
(e)(3), employers must limit access to regulated areas and under 
paragraph (e)(4), employers must provide each employee and designated 
employee representative entering a regulated area with an appropriate 
respirator (in accordance with paragraph (g) of the standard) and 
require each employee and designated employee representative to use the 
respirator while in a regulated area.
    Based on OSHA (2016), OSHA derived unit cost estimates for 
establishing and maintaining regulated areas to comply with these 
requirements and estimated that one area would be necessary for every 
eight workers in general industry and maritime exposed above the PEL. 
Planning time for a regulated area is estimated to be an initial seven 
hours of supervisor time (initial cost of $282.67 in 2012 dollars), and 
one hour for changes annually (at a cost of $40.38 in 2012 dollars); 
material costs for signs and boundary markers (annualized at $66.93 in 
2012 dollars); and costs of $526 annually for two disposable 
respirators per day to be used by authorized persons (other than those 
who regularly work in the regulated area) who might need to enter the 
area in the course of their job duties. Tables V-25 in the FEA shows 
the cost assumptions and unit costs applied in OSHA's cost model for 
regulated areas in general industry and maritime. Overall, OSHA 
estimates that each regulated area would, on average, cost employers 
$666 annually in general industry and maritime.
7. Written Exposure Control Plans
    A written exposure control plan provision was not included in the 
silica proposal, and no costs for a written exposure control plan were 
estimated in the PEA. Paragraph (f)(2) in the final standard for 
general industry and paragraph (g) in the final standard for 
construction specify the following requirements for a written exposure 
control plan: (i) A description of the tasks in the workplace that 
involve exposure to respirable crystalline silica; (ii) a description 
of the engineering controls, work practices, and respiratory protection 
used to limit employee exposure to respirable crystalline silica for 
each task; (iii) a description of the housekeeping measures used to 
limit employee exposure to respirable crystalline silica; and (iv) for 
construction, a description of the procedures used to restrict access 
to work areas, when necessary, to minimize the number of employees 
exposed to respirable crystalline silica and their level of exposure, 
including exposures generated by other employers or sole proprietors.
    In the FEA, Table V-27 shows the unit costs and assumptions for 
written exposure control plans in general

[[Page 16517]]

industry and Tables V-72 and V-74 show, respectively the unit costs for 
developing and implementing written exposure control plans in 
construction.
    Unit costs for a written exposure control plan were calculated 
based on establishment size, and the Agency assumed, for costing 
purposes, that a supervisor will develop and update the written 
exposure control plan for each establishment, spending 1 hour for 
establishments with fewer than 20 employees, 4 hours for those 
establishments with between 20 and 499 employees, and 16 hours for 
those establishments with 500 or more employees. OSHA estimated that 1 
hour would be sufficient for very small establishments because there 
is, on average, barely more than 1 worker covered by the standard per 
very small establishment in general industry and maritime.
    OSHA further determined that the additional supervisory time needed 
to review and evaluate the effectiveness of the plan, and to update it 
as necessary, will also vary by establishment size. OSHA estimated 0.5 
hours for establishments with fewer than 20 employees, 2 hours for 
those with between 20 and 499 employees, and 8 hours for those with 500 
or more employees to perform the annual review and update. The Agency 
expects that no other labor or materials will be required to implement 
the plan, so the sole cost for this provision is the time it will take 
to develop, review, and update the plan.
    In the context of general industry or maritime activities in 
permanent facilities, the implementation of the written exposure 
control plan will not typically involve significant time or effort 
above existing operations. In construction, however, employers may be 
faced with new costs to implement the written exposure plan as they 
move from site to site. OSHA has therefore included costs for 
implementation, in addition to the costs for development of the plan, 
for construction activities. The plan must be implemented by a 
``competent person,'' and OSHA has addressed the additional costs for 
training the competent person after the discussion of the general 
implementation costs.
    Paragraph (g)(4) requires the employer to designate a competent 
person to implement the exposure control plan, and restrict access to 
work areas, when necessary, to minimize the number of employees exposed 
to respirable crystalline silica and their level of exposure, including 
exposures generated by other employers or sole proprietors. The 
competent person has two broad options to restrict access to work areas 
when necessary: (1) Notifying or briefing employees, or (2) direct 
access control. The direct access control component is similar to the 
written access control plan included in the PEA, which OSHA has 
replaced with the written exposure control plan in the final rule. 
While the requirements for the written exposure control plan are more 
performance-oriented and thus should provide more flexibility for 
employers and reduce the cost of compliance, OSHA has estimated the 
costs of these options using, where appropriate, comparable components 
of the regulated area and written access control plan costs estimated 
in the PEA.
    For the employee notification or briefing option, OSHA estimated 
that, on average, it will take the competent person 15 minutes (0.25 
hours) per job to revise the briefing plan, that each job will last 10 
work-days, and that there are 150 construction working days in a year 
(Document ID 1709, p. 4-6). OSHA further estimated that it will take 
the competent person 6 minutes (0.1 hours) to brief each at-risk crew 
member (where an at-risk crew member could be an employee, a 
contractor, a subcontractor, or other worker under the control of the 
competent person) and that each crew consists of 4 at-risk workers. As 
shown in Table V-74 in the FEA, the annual cost of the job briefing 
option is $105.25 per at-risk crew member.
    For the direct access control option, OSHA estimated that, on 
average, it will take the competent person 15 minutes (0.25 hours) per 
job to revise the plan concerning direct access control and, again, 
that each job will last 10 work-days and that there are 150 
construction working days in a year. Thus, OSHA estimates that, on 
average, each employer would implement a direct access control 15 times 
per year over a total of 3.75 hours per year.
    OSHA also added the cost of signage and tape for constructing 
physical barriers: 100 feet of hazard tape (per job) and three warning 
signs. These costs are all displayed in Table V-74 in the FEA. As also 
shown there, the annualized cost of the direct access control option is 
$71.40 per at-risk crew member.
    As discussed in the Summary and Explanation section of this 
preamble concerning the written exposure control plan, restricting 
access is necessary where respirator use is required under Table 1 or 
when an exposure assessment reveals that exposures are in excess of the 
PEL, or in other situations identified by the competent person. On the 
other hand, when exposure to respirable crystalline silica is being 
successfully contained by engineering controls and work practices 
specified in Table 1 and no respirator use is required by Table 1, 
implementation of access control procedures is not required.
    OSHA assumed that, in restricting access, half the time employers 
would use the briefing option and the other half of the time they would 
use direct access control. Consequently, as shown in Table V-74, the 
annualized cost of restricting access to work areas is $88.33 per at-
risk crew member.
    As specified in paragraph (g)(4) of the final standard, a competent 
person must carry out the responsibilities of implementing the written 
exposure control plan. As defined in the standard, ``competent person'' 
means an individual who is capable of identifying existing and 
foreseeable respirable crystalline silica hazards in the workplace and 
who has authorization to take prompt corrective measures to eliminate 
or minimize them, as well as has the knowledge and ability necessary to 
fulfill the responsibilities set forth in paragraph (g) of the 
standard. OSHA has utilized the competent person provision in other 
construction standards, such as 1926.1127, Cadmium, and 1926.1101, 
Asbestos, so the Agency expects that there is widespread familiarity 
with both the concept and the responsibilities of competent person in 
the construction sector. As in other OSHA construction rules, a major 
purpose of the competent person provision in this final silica standard 
is to identify who has the responsibility for inspections of the job 
sites, materials, and equipment. Thus, OSHA expects that most employers 
will have training programs in place to produce competent persons, and 
the cost of training someone will only be a relatively small marginal 
increase in the overall training cost. For that reason, the Agency 
expects that many employees designated as competent persons will 
undergo some training for the position. OSHA is estimating that each 
competent person will, on average, undergo two hours of training--in 
addition to the one hour of silica training estimated for all 
construction employees. OSHA does not anticipate any additional costs 
beyond training costs to be associated with the requirement that a 
competent person implement the written exposure control plan.
    While the competent person provision does not specify a training 
requirement, the competent person is required to possess the knowledge 
and skills to perform the functions required by the standard. For that 
reason, the Agency expects that many employees designated as competent 
persons will undergo some training for the position.

[[Page 16518]]

OSHA estimates that, on average, there will be 1 competent person for 
each establishment with fewer than 20 employees, 5 competent persons 
for each establishment with 20-499 employees, and 10 competent persons 
for each establishment with 500 or more employees.
    OSHA expects that competent persons will be trained by a 
supervisor, presumably one who went through the process to become 
familiar with the requirements of the respirable crystalline silica 
standard, or by a combination of supervisory and/or technical staff 
that are familiar with the operation of the engineering controls. While 
the competent persons are not required to be supervisors and some of 
the staff providing the training may not be supervisors, OSHA is using 
a supervisor's wage to estimate the costs for time spent by both the 
trainers and the trainees in order to provide the upper cost limit, 
realizing that the cost for establishments who do not designate 
supervisors as the competent person will be lower. OSHA estimated that 
the total cost per establishment to train a competent person in 
construction will range from $21 to $114 (see Chapter V in the FEA for 
a full discussion of OSHA's analysis of costs for written exposure 
control plans under the final standard).
8. Combined General Industry/Maritime Control, Respirator, and Program 
Costs
    Table VII-14 shows that the estimated combined costs for employers 
in the general industry and maritime sectors to comply with the final 
silica rule are approximately $370.8 million annually. These costs 
include $238.1 million annually for engineering controls and $10.5 
million annually for respirators to meet the final PEL of 50 [mu]g/
m\3\. The remaining $122.2 million annually are to meet the ancillary 
provisions of the final rule. These ancillary annual costs consist of 
$79.6 million for exposure monitoring; $29.7 million for medical 
surveillance; $6.0 million for familiarization and training; $2.6 
million for regulated areas; and $4.1 million for the written exposure 
control plan.
    Table V-B-1 in Appendix V-B in the FEA presents estimated 
compliance costs by NAICS industry code and program element for small 
business entities (as defined by the Small Business Act and the Small 
Business Administration's implementing regulations; see 15 U.S.C. 632 
and 13 CFR 121.201) in general industry and maritime, while Table V-B-2 
in the FEA presents estimated compliance costs, by NAICS code and 
program element, for very small entities (fewer than twenty employees) 
in general industry and maritime.
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BILLING CODE 4510-26-C
9. Combined Construction Control, Respirator, and Program Costs
    Table VII-15 summarizes the engineering control costs, respirator 
costs, and program costs of the rule for the construction sector. 
Annualized compliance costs in construction are expected to total 
$659.0 million, of which $423.4 million are for engineering controls, 
$22.4 million are for respirators, and $213.2 million are to meet the 
ancillary provisions of the rule. These ancillary annual costs consist 
of $16.5 million for exposure monitoring; $66.7 million for medical 
surveillance; $89.9 million for familiarization and

[[Page 16526]]

training; and $40.1 million for the written exposure control plan.
    Table V-B-1 in Appendix V-B in the FEA presents estimated 
compliance costs by NAICS industry code and program element for small 
entities (as defined by the Small Business Administration) in 
construction, while Table V-B-2 in the FEA presents estimated 
compliance costs, by NAICS code and program element, for very small 
entities (fewer than twenty employees) in construction.
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[[Page 16527]]


BILLING CODE 4510-26-C
10. Total Cost Summary
    As shown in Table VII-16, annualized compliance costs associated 
with the rule are expected to total $1,030 million. Table VII-16 also 
provides total annualized costs for general industry, maritime, and 
construction separately, by major provision or program element included 
in the rule. This table shows that engineering control costs represent 
64 percent of the costs of the standard for all three affected industry 
sectors: general industry, maritime, and construction. Considering 
other leading cost categories, costs for exposure assessment and 
medical surveillance represent, respectively, 30 percent and 15 percent 
of the costs of the standard for general industry and maritime; costs 
for training and familiarization and medical surveillance represent, 
respectively, 14 percent and 10 percent of the costs of the standard 
for construction.
    While the costs presented here represent the Agency's best estimate 
of the costs to industry of complying with the rule under static 
conditions (that is, using existing technology and the current 
deployment of workers), OSHA recognizes that actual costs could be 
somewhat higher or lower, depending on the Agency's possible 
overestimation or underestimation of various cost factors. In Chapter 
VII of the FEA, OSHA provides a sensitivity analysis of its cost 
estimates by modifying certain critical unit cost factors. Beyond this 
sensitivity analysis, OSHA notes that its cost estimates do not reflect 
the possibility that, in response to the rule, industry may find ways 
to reduce compliance costs.
    This could be achieved in three ways. First, in construction, 36 
percent of the estimated costs of the rule (all costs except 
engineering controls) vary directly with the number of workers exposed 
to silica. However, as shown in Table III-5 in the FEA, more than five 
times as many construction workers will be affected by the rule as will 
the number of full-time-equivalent construction workers necessary to do 
the work. This is because most construction workers currently doing 
work involving silica exposure perform such tasks for only a portion of 
their workday. In response to the rule, many employers are likely to 
assign work so that fewer construction workers perform tasks involving 
silica exposure; correspondingly, construction work involving silica 
exposure will tend to become a full-time job for some construction 
workers.\47\ Were this approach fully implemented in construction, the 
actual cost of the rule would decline because employers would have to 
comply with the ancillary provisions of the final rule for fewer 
workers.\48\ However, these workers would be subject to the full 
protections of the final rule.
---------------------------------------------------------------------------

    \47\ There are numerous instances of job reassignments and job 
specialties arising in response to OSHA regulation. For example, 
asbestos removal and confined space work in construction have become 
activities performed by well-trained specialized employees, not 
general laborers (whose only responsibility is to identify the 
presence of asbestos or a confined space situation and then to 
notify the appropriate specialist).
    \48\ OSHA expects that such a structural change in construction 
work assignments would not have a significant effect on the benefits 
of the rule. As discussed in Chapter VII of this PEA, the estimated 
benefits of the rule are relatively insensitive to changes in 
average occupational tenure or how total silica exposure in an 
industry is distributed among individual workers.
---------------------------------------------------------------------------

    Second, industry could demonstrate that certain construction 
activities result in exposures below the action level under any 
foreseeable conditions--in which case, workers engaged only in those 
silica-generating activities would not be subject to the requirements 
of the final rule. For example, an employer could make this 
demonstration by using objective data developed for short-term, 
intermittent tasks involving limited generation of silica dust. In 
estimating the costs for this final rule, however, OSHA included all 
costs, including ancillary costs as appropriate, associated with short-
term intermittent silica tasks.
    Third, the costs presented here do not take into account the 
possible development and dissemination of cost-reducing compliance 
technology in response to the rule.\49\ One possible example is the 
development of safe substitutes for silica sand in activities such as 
abrasive blasting operations, repair and replacement of refractory 
materials, foundry operations, and in the railroad transportation 
industry. Another is expanded use of automated processes which would 
allow workers to be isolated from the points of operation that involve 
silica exposure (such as tasks between the furnace and the pouring 
machine in foundries and at sand transfer stations in structural clay 
production facilities). Yet another example is the further development 
and use of bags with valves that seal effectively when filled, thereby 
preventing product leakage and worker exposure (for example, in mineral 
processing and concrete products industries). Probably the most 
pervasive and significant technological advances, however, will likely 
come from the integration of compliant control technology into standard 
production equipment. Such advances would both increase the 
effectiveness and reduce the costs of silica controls when compared to 
retrofitted production equipment. Possible examples include local 
exhaust ventilation (LEV) systems attached to portable tools used by 
grinders and tuckpointers; enclosed operator cabs equipped with air 
filtration and air conditioning in industries that mechanically 
transfer silica or silica-containing materials; and machine-integrated 
wet dust suppression systems used, for example, in road milling 
operations.\50\
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    \49\ Evidence of such technological responses to regulation 
includes Ashford, Ayers, and Stone (1985)(Document ID 0536), OTA 
(1995)(Document ID 0947), and OSHA's regulatory reviews of existing 
standards under Sec.  610 of the Regulatory Flexibility Act (``610 
lookback reviews''). On the other hand, supplemental evidence from 
Harrington et al. (2000) [Harrington, Winston, Richard D. 
Morgenstern and Peter Nelson. ``On the Accuracy of Regulatory Cost 
Estimates.'' Journal of Policy Analysis and Management, 19(2), 297-
322, 2000] finds that OSHA does not systematically overestimate 
costs on a per-unit basis. Nevertheless, several examples of OSHA's 
overestimation of costs reported in the article are due to 
technological improvements.
    \50\ A dramatic example from OSHA's 610 lookback review of its 
1984 ethylene oxide (EtO) standard is the use of EtO as a sterilant. 
OSHA estimated the costs of then existing add-on controls for EtO 
sterilization, but in response to the standard, improved EtO 
sterilizers with built-in controls were developed and widely 
disseminated at about half the cost of the equipment with add-on 
controls. (See OSHA, 2005.) Lower-cost EtO sterilizers with built-in 
controls did not exist, and their development had not been predicted 
by OSHA, at the time the final rule was published in 1984.
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    OSHA has decided not to include in its analysis any possible cost-
reducing technological advances or worker specialization because the 
technological and economic feasibility of the rule can easily be 
demonstrated using existing technology and employment patterns. 
However, OSHA believes that actual costs, which will incorporate any 
future developments of this type, will likely be lower than those 
estimated here.
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BILLING CODE 4510-26-C

[[Page 16529]]

a. Costs Under Alternative PEL (100 [mu]g/m\3\) Scenario
    Appendix V-C in the FEA presents, for analytical purposes, costs 
for an alternative PEL of 100 [mu]g/m\3\. Total annualized compliance 
costs under this alternative are $649.3 million. Table V-C-1 displays 
costs for general industry, maritime, and construction by each program 
element. Table V-C-2 shows total costs by NAICS industry code for all 
affected general industry and maritime establishments, for business 
entities in general industry and maritime defined as small by the Small 
Business Administration, and for very small business entities in 
general industry and maritime (those with fewer than twenty employees). 
Table V-C-3 shows total costs by NAICS industry code for all affected 
construction establishments, for business entities in construction 
defined as small by the Small Business Administration, and for very 
small business entities in construction (those with fewer than twenty 
employees).
b. Costs Under Alternative Discount Rates
    An appropriate discount rate \51\ is needed to reflect the timing 
of costs after the rule takes effect and to allow conversion to an 
equivalent steady stream of annualized costs.
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    \51\ Here and elsewhere throughout the FEA, unless otherwise 
noted, the term ``discount rate'' always refers to the real discount 
rate--that is, the discount rate net of any inflationary effects.
---------------------------------------------------------------------------

c. Alternative Discount Rates for Annualizing Costs
    Following OMB (2003) guidelines (Document ID 1493), OSHA has 
estimated the annualized costs of the rule using separate discount 
rates of 3 percent and 7 percent. Consistent with the Agency's own 
practices in recent proposed and final rules,\52\ OSHA has also 
estimated, for benchmarking purposes, undiscounted costs--that is, 
costs using a zero percent discount rate.
---------------------------------------------------------------------------

    \52\ See, for example, 71 FR 10099, the preamble for the final 
hexavalent chromium rule.
---------------------------------------------------------------------------

d. Summary of Annualized Costs Under Alternative Discount Rates
    In addition to using a 3 percent discount rate in its main cost 
analysis, OSHA estimated compliance costs, in Appendix V-D in the FEA, 
using alternative discount rates of 7 percent and zero percent. Table 
V-D-1 and V-D-2 in Appendix V-D present total costs at a 7 percent 
discount rate for both (1) all employers by major industry category and 
program element, and (2) affected employers by NAICS industry code and 
employment size class (all establishments, small entities, and very 
small entities). Tables V-D-3 and V-D-4 present the same breakdowns of 
total costs estimated at a zero percent discount rate.
    As shown in Appendix V-D, the choice of discount rate has only a 
minor effect on total annualized compliance costs, with annualized 
costs increasing from 1,030 million using a three percent discount rate 
to $1,056 million using a seven percent discount rate, and decreasing 
to $1,012 million using a zero percent discount rate.
e. Time Distribution of Costs
    OSHA analyzed the stream of (unannualized) compliance costs, by 
industry sector, for the first ten years after the rule takes effect 
under the simplifying assumption that no provisions of the rule are 
phased in. As shown in Table VII-16, total compliance costs are 
expected to peak in Year 1 at more than $1.5 billion. After that, costs 
are estimated to decline and remain relatively flat after the initial 
set of capital and program start-up expenditures has been incurred. 
Costs are projected to rise somewhat in Year 4 as a result of the 
triennial medical examinations and in Year 6 because of a second cycle 
of control equipment purchases in construction for short-term, 
intermittent work. Thereafter there are fluctuations but no strong 
trend. OSHA notes that the differences between costs for Year 1 and 
costs for subsequent years are narrower than might otherwise be the 
case due to (1) the expectation that, in the construction sector, a 
large percentage of control equipment will be rented (leading to 
constant annual expenses for the rented control equipment) rather than 
purchased as capital in Year 1; and (2) the expectation that the only 
engineering controls needed in the maritime sector will be wet methods, 
which do not require capital expenditures. On the other hand, the 
ancillary provisions are expected to have a relatively large number of 
initial costs (mainly labor rather than capital) in Year 1.

[[Page 16530]]

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F. Economic Feasibility Analysis and Regulatory Flexibility 
Determination

    Chapter VI of the FEA presents OSHA's analysis of the economic 
impacts of its final silica rule on affected employers in general 
industry, maritime, and construction. The discussion below summarizes 
the findings in that chapter.
    As a first step, the Agency explains its approach for achieving the 
two major objectives of its economic impact analysis: (1) To establish 
whether the final rule is economically feasible for all affected 
industries, and (2) to determine if the Agency can certify that the 
final rule will not have a significant economic impact on a substantial 
number of small entities. Next, this approach is applied to industries 
with affected employers in general industry and maritime and then to 
industries with affected employers in construction. Finally, OSHA 
examines the employment effects of the silica rule. This includes a 
review of estimates of employment effects that commenters provided and 
a summary of a report prepared for the Agency by Inforum--a not-for-
profit corporation (based at the University of Maryland) specializing 
in the design and application of macroeconomic models of the United

[[Page 16531]]

States (and other countries)--to estimate the industry and aggregate 
employment effects of the silica rule.
    Many commenters questioned OSHA's preliminary conclusions 
concerning economic feasibility, but did so for reasons that OSHA has 
responded to in previous chapters.
    A variety of commenters raised issues concerning industries with 
possible silica exposure that were not covered in the Preliminary 
Economic and Initial Regulatory Feasibility Analysis (PEA). A full 
discussion of these comments and of industries added is provided in the 
FEA.
    Many commenters questioned why OSHA used no data after 2006 (see 
comments by the Brick Industry Association (BIA) (Document ID 2300, p. 
5), the American Fuel & Petrochemical Manufacturers (AFPM) (Document ID 
2350, p. 6), the Belden Brick Company (Document ID 3260, p. 3), 
Basalite Concrete Products, LLC (Document ID 2083, p. 1), SBG 
Consulting (Document ID 2222, p. 1), Acme Brick (Document ID 2182, p. 
4), Erie Bronze & Aluminum (Document ID 1780, p. 1), Calstone (Document 
ID 3391, p. 2), the Chamber of Commerce (Document ID 1782, p. 1), the 
Mason Contractors Association of America (MCAA) (Document ID 1767, p. 
2), Scango Consulting LLC d.b.a. Capitol Hardscapes (Document ID 2241, 
p. 3), the National Concrete Masonry Association (NCMA) (Document ID 
3585, p. 2944), the American Road and Transportation Builders 
Association (ARTBA) (Document ID 2245, p. 4), and the Construction 
Industry Safety Coalition (CISC) (Document ID 4217, Attachment 1, pp. 4 
and 49-52)). As discussed in Chapter III of the FEA, OSHA is using 
revenue data from 2012 and profit data averaged across the years 2000 
through 2012. The revenue data from 2012 represent a reasonable choice 
because this year was neither a peak growth year nor a recession year 
and was the most up-to-date data available at the time this analysis 
was developed. The range of years for profits assures the use of profit 
rates from throughout the business cycle--including two recessions and 
two sustained growth periods.
    One commenter questioned OSHA's sources and methodology for 
estimating revenues (Document ID 2308, Attachment 9, pp. 7-8 and 14-
16). This commenter questioned the methodology used to update revenue 
estimates between Economic Census years. This is no longer an issue as 
OSHA is using 2012 Economic Census data and using 2012 as the base year 
for the analysis. Therefore, there is no need for a methodology to 
update Economic Census revenues.
    OSHA also received criticism on the choice of the data source and 
the methodology for estimating profits of the construction industry. 
These include comments from the National Association of Home Builders 
(NAHB) and the CISC (Document ID 2296, Attachment 1, pp. 20-22; 2308, 
Attachment 9, pp. 7-12).
    Stuart Sessions, submitting on behalf of the CISC, criticized OSHA 
for using the Internal Revenue Service's (IRS) Corporation Source Book 
(CSB) as the source for industry profits since those data are only 
presented at the four-digit NAICS level instead of the five- or six-
digit NAICS level. Mr. Sessions recommended that OSHA use an 
alternative data source for profit data and recommended Bizminer or RMA 
(Document ID 4231, Attachment 1, pp.12-13). OSHA investigated these 
sources and determined that these data were private data sources and 
that their publishers would not allow the data to be made publicly 
available. These other sources of profit data also suffered from the 
disadvantage of not representing adequate and random samples of the 
affected industries. A further discussion on this issue appears in 
Chapter III of the FEA.
    In the PEA, OSHA used IRS data to calculate profit rates as the 
ratio of net income to total receipts (with the numerator including 
only firms with positive net income and the denominator including firms 
with and without net income) by NAICS industry. In response to comments 
criticizing this ratio as an inappropriate method to calculate industry 
profitability (Document ID 2308, Attachment 9, pp. 11-12; 4209, pp. 
115-116), OSHA has revised the way that estimated profits are 
calculated. In the FEA, OSHA calculates profit rates using the method 
recommended by Mr. Sessions, which is discussed more fully in Chapter 
III. This method includes unprofitable firms and divides the ``net 
income'' from all firms (profitable and unprofitable) by total receipts 
from all firms (profitable and unprofitable), resulting in somewhat 
lower profit rates.
    Similarly, Mr. Sessions criticized OSHA for using data that he 
believed were at a level that was too aggregated to show economic 
impacts of the costs of the rule accurately (Document ID 2319, 
Attachment 1, p. 71). The Portland Cement Association likewise 
disagreed with OSHA's presentation of costs as averages across 
industries. It said that ``a more focused explanation of individual 
plant and facility costs is relevant to those industries with 
significant compliance responsibilities'' (Document ID 2284, p. 6). 
OSHA's data sources for profile data are presented in Chapter III of 
the FEA. In general, OSHA has disaggregated industries to the extent 
that the source data will allow.
    The most common criticism of OSHA's preliminary conclusions on 
economic feasibility was that the conclusions were based on costs that 
were underestimated or inaccurate (e.g., Document ID 2023, p. 1; 2299, 
p. 15; 2379, Attachment 3, pp. 2 and 10; 2388, pp. 2 and 10; 2296, 
Attachment 1, p. 17; 2116, Attachment 1, p. 22; and 3378, Attachment 
2). For example, Wayne D'Angelo of the American Petroleum Institute 
(API) and the Independent Petroleum Association of America (IPAA) (API/
IPAA or ``the Associations'') critiqued OSHA's feasibility analysis for 
the hydraulic fracturing industry, stating that OSHA had not met its 
obligations due to inaccurate cost data and an industry profile that, 
they asserted, did not ``reasonably represent the typical firms in the 
various segments of the industry, given varying operations, exposure 
levels, and processes'' (Document ID 2301, Attachment 1, pp. 62-63).
    OSHA responded to comments on its preliminary cost estimates in 
Chapter V of the FEA. In the aggregate, OSHA increased its cost 
estimate by approximately 46 percent, in part, as a result of changes 
in cost estimates made in response to comments and, in part, as a 
result of changes in the rule.
    Some commenters argued that OSHA had not adequately considered the 
possibility that smaller establishments might have higher costs or that 
the costs have a greater impact on small businesses (Document ID 4231, 
Attachment 1, p. 11; 2379, Attachment 2, p. 7; 3582, Tr. 2107-2109; 
2203, p. 1; 2351, p. 8; 3433, p. 9; 3580, Tr. 1398). As discussed in 
Chapter V, OSHA has made a number of changes to the costs analysis to 
reflect higher costs for small establishments.
1. Analytic Approach
a. Economic Feasibility
    The Court of Appeals for the D.C. Circuit has long held that OSHA 
standards are economically feasible so long as their costs do not 
threaten the existence of, or cause massive economic dislocations 
within, a particular industry or alter the competitive structure of 
that industry. American Iron and Steel Institute. v. OSHA, 939 F.2d 
975, 980 (D.C. Cir. 1991); United Steelworkers of America, AFL-CIO-CLC 
v. Marshall, 647 F.2d 1189, 1265 (D.C. Cir. 1980); Industrial Union 
Department

[[Page 16532]]

v. Hodgson, 499 F.2d 467, 478 (D.C. Cir. 1974).
    In practice, the economic burden of an OSHA standard on an 
industry--and whether the standard is economically feasible for that 
industry--depends on the magnitude of compliance costs incurred by 
establishments in that industry and the extent to which they are able 
to pass those costs on to their customers. That, in turn, depends, to a 
significant degree, on the price elasticity of demand for the products 
sold by establishments in that industry.
    The price elasticity of demand refers to the relationship between 
the price charged for a product and the demand for that product: The 
more elastic the relationship, the less an establishment's compliance 
costs can be passed through to customers in the form of a price 
increase and the more it has to absorb compliance costs in the form of 
reduced profits. When demand is inelastic, establishments can recover 
most of the variable costs of compliance (i.e., costs that are highly 
correlated with the amount of output) by raising the prices they 
charge; under this scenario, if costs are variable rather than fixed, 
profit rates are largely unchanged and the industry remains largely 
unaffected. Any impacts are primarily on those customers using the 
relevant product. On the other hand, when demand is elastic, 
establishments cannot recover all compliance costs simply by passing 
the cost increase through in the form of a price increase; instead, 
they must absorb some of the increase from their profits. Commonly, 
this will mean reductions both in the quantity of goods and services 
produced and in total profits, though the profit rate may remain 
unchanged. Other things being equal, higher fixed costs mean that the 
optimal scale of the typical establishment will be larger than it would 
be if fixed costs were lower. This in turn means that, where there are 
higher fixed costs, there will be fewer plants for the same level of 
production. Whether an increase in fixed costs results in closures of 
existing plants depends on several factors. If demand regularly 
increases (such as due to economic growth) or the industry regularly 
experiences plant closures, the optimal scale may be arrived at by 
reduced entry rather than premature closures. If plants are not part of 
a simple homogeneous market, it may not be possible to shift the scale 
of production. For example, if a plant provides foundry products to 
others in the same city, it may not be able to readily expand its scale 
of production. In general, ``[w]hen an industry is subjected to a 
higher cost, it does not simply swallow it; it raises its price and 
reduces its output, and in this way shifts a part of the cost to its 
consumers and a part to its suppliers,'' in the words of the court in 
American Dental Association v. Secretary of Labor (984 F.2d 823, 829 
(7th Cir. 1993)).
    The court's summary is in accord with microeconomic theory. In the 
long run, firms can remain in business only if their profits are 
adequate to provide a return on investment that ensures that investment 
in the industry will continue. As technology and costs change, however, 
the long-run demand for some products naturally increases and the long-
run demand for other products naturally decreases. In the face of 
additional compliance costs (or other external costs), firms that 
otherwise have a profitable line of business may have to increase 
prices to stay viable. Increases in prices typically result in reduced 
quantity demanded, but rarely eliminate all demand for the product. 
Whether this decrease in the total production of goods and services 
results in smaller output for each establishment within the industry, 
or the closure of some plants within the industry; a reduced number of 
new establishments entering the industry; or a combination of the 
three, is dependent on the cost and profit structure of individual 
firms within the industry.
    If demand is perfectly inelastic (i.e., the price elasticity of 
demand is zero), then the impact of compliance costs that are 1 percent 
of revenues for each firm in the industry would result in a 1 percent 
increase in the price of the product, with the quantity demanded 
constant. (This outcome would hold in the long run, regardless of type 
of costs, but in the short run would hold with certainty only if 
compliance costs are strictly variable.) Such a scenario represents an 
extreme case, but might be observed in situations in which there were 
few if any substitutes for the product in question, or if the products 
of the affected sector account for only a very small portion of the 
revenue or income of its customers. Under this scenario, both profits 
and output of the industry would be unaffected, but customers would be 
worse off.
    If the demand is perfectly elastic (i.e., the price elasticity of 
demand is infinitely large), then no increase in price is possible and 
before-tax profits would be reduced by an amount equal to the costs of 
compliance (net of any cost savings--such as reduced workers' 
compensation insurance premiums--resulting from the final standard) if 
the industry attempted to maintain production at the same level. Under 
this scenario, if the costs of compliance are such a large percentage 
of profits that some or all plants in the industry could no longer 
operate with the hope of an adequate return on investment, then some or 
all of the firms would close. Similarly, if compliance costs are fixed, 
such costs may result in premature closures or reduced entry into the 
market in some circumstances.
    A commonly discussed intermediate case would be a price elasticity 
of demand of one.\53\ In this scenario, if the costs of compliance 
amount to 1 percent of revenues, then production would decline by 1 
percent and prices would rise by 1 percent. (As before, this outcome 
would hold in the long run, regardless of type of costs, but in the 
short run would hold with certainty only if compliance costs are 
variable.) Under this scenario, and if marginal costs of the regulation 
fall proportionally with output, then industry revenues would remain 
the same, with somewhat lower production, but with similar profit 
rates. Customers would, however, receive less of the product for their 
(same) expenditures, and firms would have lower total profits; this, as 
the court described in Am. Dental Ass'n v. Sec'y of Labor, 984 F.2d 823 
(7th Cir. 1993), is the more typical case.
---------------------------------------------------------------------------

    \53\ Here and throughout this section, the price elasticity of 
demand is reported as an abosulte value.
---------------------------------------------------------------------------

    A decline in output as a result of an increase in price may occur 
in a variety of ways: Individual establishments could each reduce their 
levels of production; some marginal plants could close; or, in the case 
of an industry with high turnover of establishments, new entry may be 
delayed until demand equals supply. In many cases a decrease in overall 
output for an industry will be a combination of all three kinds of 
reductions. Which possibility is most likely depends on the rate of 
turnover in the industry and on the form that the costs of the 
regulation take.
    When turnover in an industry is high, or an industry is expanding 
rapidly, then the key issue is the long run costs as determined by the 
cost of entry into the industry. For example, if there is annual 
turnover in an industry of ten percent per year, and a price elasticity 
of one, then a single year without new entry would result in a price 
rise of ten percent. Such a rise would be more than enough to 
compensate existing employers for a cost increase of one percent of 
revenues. If the costs are variable costs (i.e., costs that vary with 
the level of production at a facility), then economic theory suggests 
that any reductions in output will take the form

[[Page 16533]]

of reductions in output at each affected facility, with few, if any, 
plant closures. If the costs of a regulation primarily take the form of 
fixed costs (i.e., costs that do not vary with the level of production 
at a facility), and assuming perfect competition, then reductions in 
overall output are more likely to can only take the form of plant 
closures or delays in new entry. Most of the costs of this regulation, 
as estimated in Chapter V of the FEA, are variable costs. Almost all of 
the major costs of program elements, such as medical surveillance and 
training, will vary in proportion to the number of employees (which is 
a rough proxy for the amount of production). Exposure monitoring costs 
will vary with the number of employees, but do have some economies of 
scale to the extent that a larger firm need only conduct representative 
sampling rather than sample every employee. The costs of engineering 
controls in construction also vary by level of production because 
almost all necessary equipment can readily be rented and the 
productivity costs of using some of these controls vary proportionally 
to the level of production. Finally, the costs of operating engineering 
controls in general industry (the majority of the annualized costs of 
engineering controls are in general industry) vary by the number of 
hours the establishment works, and thus vary by the level of production 
and are not fixed costs in the strictest sense.
    This leaves two kinds of costs that are, in some sense, fixed 
costs--capital costs of engineering controls in general industry and 
certain initial costs that new entrants to the industry will not have 
to bear.
    Fixed costs in the form of capital costs of engineering controls in 
general industry and maritime due to this standard are relatively small 
as compared to the total costs, representing less than 21 percent of 
total annualized costs and approximately $1,019 per year per affected 
establishment in general industry.
    There are some initial fixed costs in the sense that they might 
only be borne by firms in the industry today. For example, costs for 
general training not currently required and initial costs of medical 
surveillance may not be borne by establishments new to the industry to 
the extent they can hire from a workforce that may have already had 
this training and/or initial medical surveillance. An initial thorough 
facility cleaning is not a cost a new establishment would need to bear. 
These costs will disappear after the initial year of the standard and 
thus would be difficult to pass on. These costs, however, represent 
less than two percent of total costs and less than $58 per affected 
establishment. These initial fixed costs that may be borne by firms in 
the affected industries today, together with capital costs, give a 
total fixed cost of approximately 22 percent of total annual costs.
    Because the remaining three-fourths of the total annual costs are 
variable, OSHA expects it is somewhat more likely that reductions in 
industry output resulting from the increase in costs associated with 
this rule will be met by reductions in output at each affected facility 
rather than as a result of plant closures or reduced new entry. 
However, closures of some marginal plants or poorly performing 
facilities are always possible. To determine whether a rule is 
economically feasible, OSHA begins with two screening tests to consider 
minimum threshold effects of the rule under two extreme cases: (1) All 
costs are passed through to customers in the form of higher prices 
(consistent with a price elasticity of demand of zero), and (2) all 
costs are absorbed by the firm in the form of reduced profits 
(consistent with an infinite price elasticity of demand).
    In the former case, the immediate impact of the rule would be 
observed in increased industry revenues. While there is no hard and 
fast rule, in the absence of evidence to the contrary, OSHA generally 
considers a standard to be economically feasible for an industry when 
the annualized costs of compliance are less than a threshold level of 
one percent of annual revenues. Retrospective studies of previous OSHA 
regulations have shown that potential impacts of such a small magnitude 
are unlikely to eliminate an industry or significantly alter its 
competitive structure,\54\ particularly since most industries have at 
least some ability to raise prices to reflect increased costs and, as 
shown in the FEA, normal price variations for products typically exceed 
three percent a year.\55\ Of course, OSHA recognizes that even when 
costs are within this range, there could be unusual circumstances 
requiring further analysis.
---------------------------------------------------------------------------

    \54\ See OSHA's Web page, http://www.osha.gov/dea/lookback.html#Completed, for a link to all completed OSHA lookback 
reviews.
    \55\ See, for example, Table VI-3 and the accompanying text 
presented in Chapter VI of the FEA.
---------------------------------------------------------------------------

    In the latter case, the immediate impact of the rule would be 
observed in reduced industry profits. OSHA uses the ratio of annualized 
costs to annual profits as a second check on economic feasibility. 
Again, while there is no hard and fast rule, in the absence of evidence 
to the contrary, OSHA generally considers a standard to be economically 
feasible for an industry when the annualized costs of compliance are 
less than a threshold level of ten percent of annual profits. In the 
context of economic feasibility, the Agency believes this threshold 
level to be fairly modest, given that normal year-to-year variations in 
profit rates in an industry can exceed 40 percent or more.\56\ OSHA's 
choice of a threshold level of ten percent of annual profits is low 
enough that even if, in a hypothetical worst case, all compliance costs 
were upfront costs, then upfront costs would still equal 88.5 percent 
of profits using a three percent discount rate (see section Normal 
Year-to-Year Variations in Prices and Profit Rates below) and thus 
would be affordable from profits alone without the need for an employer 
to resort to credit markets. If the threshold level were first-year 
costs of ten percent of annual profits, firms could even more easily 
expect to cover first-year costs at the threshold level out of current 
profits without having to access capital (including credit markets) 
markets and otherwise being threatened with short-term insolvency.
---------------------------------------------------------------------------

    \56\ See, for example, Table VI-5 and the accompanying text 
presented in Chapter VI of the FEA.
---------------------------------------------------------------------------

    In general, it is usually the case that firms would be able to pass 
on some or all of the costs of the rule to their customers in the form 
of higher prices. OSHA therefore will tend to give much more weight to 
the ratio of industry costs to industry revenues than to the ratio of 
industry costs to industry profits. However, if costs exceed either the 
threshold percentage of revenue or the threshold percentage of profits 
for an industry, or if there is other evidence of a threat to the 
viability of an industry because of the standard, OSHA will examine the 
effect of the rule on that industry more closely. Such an examination 
would include market factors specific to the industry, such as normal 
variations in prices and profits, international trade and foreign 
competition, and any special circumstances, such as close domestic 
substitutes of equal cost, which might make the industry particularly 
vulnerable to a regulatory cost increase.
    The preceding discussion focused on the economic viability of the 
affected industries in their entirety. However, even if OSHA found that 
a final standard did not threaten the survival of affected industries, 
there is still the question of whether the industries' competitive 
structure would be significantly altered. For example, if the

[[Page 16534]]

annualized costs of an OSHA standard were equal to ten percent of an 
industry's annual profits, and the price elasticity of demand for the 
products in that industry were equal to one, then OSHA would not expect 
the industry to go out of business. However, if the increase in costs 
were such that most or all small firms in that industry would have to 
close, it could reasonably be concluded that the competitive structure 
of the industry had been altered. For this reason, OSHA also examines 
the differential costs by size of establishment.
Public Comments on OSHA's Approach to Economic Feasibility
    Some commenters were concerned that reductions of profits of less 
than ten percent could still represent major losses to an employer. For 
example, one commenter said:

    The proposed rule states that in no cases will the amount of 
revenue or profits exceed 8.8% noting that this number is easily 
passed to consumers in the form of increased product and service 
costs. For a rule as specific and slight as one affecting only 
silica dust inhalation, a reduction in profits by 8.8% should give 
the government pause (Document ID 2189, p. 1).

    Another commenter expressed similar concerns about a reduction in 
profits of 4.8 percent (Document ID 1882, Attachment 1, p. 2). OSHA is 
not dismissive of losses in profits of less than ten percent. However, 
such losses need to be weighed against the OSH Act's objectives of 
occupational safety and health. For purposes of assessing economic 
feasibility, OSHA needs to be concerned with major dislocating effects 
on entire industries, which will not be the result of relatively small 
changes in profits. Further, as will be discussed below, these costs 
can likely be passed on to consumers.
    API/IPAA, while disagreeing with OSHA's cost estimates, 
acknowledged that OSHA's use of the rules of thumb of ten percent of 
profits or one percent of revenues has been upheld in court (Document 
ID 2301, Attachment 1, pp. 62-63).
    Some commenters were also concerned that OSHA's screening analysis 
methodology did not give adequate consideration to upfront costs 
(Document ID 2379, Attachment 3, p. 39; 2119, Attachment 3, p. 22). As 
will be discussed below, OSHA's choice of a threshold level of ten 
percent of annual profits is low enough that even if, in a hypothetical 
worst case, all compliance costs were upfront costs, then upfront costs 
would still equal 88.5 percent of profits and thus would be affordable 
from profits alone without needing to resort to credit markets. (If the 
cost exceeds 100 percent of profits then the company would have to 
borrow to pay the balance. Otherwise the firm will not have to borrow 
but could finance the cost internally.)
    While not specifically addressed to the issue of the screening 
analysis, Mr. Sessions provided some estimates of how various 
percentage cost increases might interact with demand and supply 
elasticities to produce estimates of declines in total industry output. 
His estimates show that the decline in total revenues (and, in this 
situation, total production) associated with increased costs of one 
percent of revenues ranges from zero to 0.83 percent of total 
production (the range depending on the elasticities of supply and 
demand, with the highest impact on total revenues associated with a 
very unlikely price elasticity of ten) (Document ID 4231, Attachment 1, 
p. 31). Even the largest decline in revenues would result in only a 
0.83 percent decline in revenues, which would not represent a major 
dislocation of any affected industry. While OSHA does not necessarily 
endorse this particular approach to calculating changes in total 
revenue for given percentage change in costs, the calculation confirms 
OSHA's general view that increases of less than one percent of costs do 
not render a standard economically infeasible.
    After reviewing these comments, OSHA has decided to retain its 
screening test of ten percent of profits and one percent of revenues as 
levels below which significant dislocation of an industry is extremely 
unlikely.
b. Regulatory Flexibility Screening Analysis
    The Regulatory Flexibility Act (RFA), Public Law 96-354, 94 Stat. 
1164 (codified at 5 U.S.C. 601), requires Federal agencies to consider 
the economic impact that a final rulemaking will have on small 
entities. The RFA states that whenever an agency ``promulgates a final 
rule under section 553 of this title, after being required by that 
section or any other law to publish a general notice of proposed 
rulemaking, the agency shall prepare a final regulatory flexibility 
analysis'' (FRFA). 5 U.S.C. 604(a). Pursuant to section 605(b), in lieu 
of an FRFA, the head of an agency may certify that the final rule will 
not have a significant economic impact on a substantial number of small 
entities. A certification must be supported by a factual basis. If the 
head of an agency makes a certification, the agency shall publish such 
certification in the Federal Register at the time of publication of 
general notice of final rulemaking or at the time of publication of the 
final rule. 5 U.S.C. 605(b). Thus, if OSHA cannot issue the required 
certification, it must prepare a FRFA.
    OSHA makes its determination about whether it can issue the 
required certification by applying screening tests to consider minimum 
threshold effects of the rule on small entities. These screening tests 
are similar in concept to those OSHA described above to identify 
minimum threshold effects for the purposes of demonstrating economic 
feasibility and are discussed below.
    There are, however, two differences. First, for each affected 
industry, the screening tests are applied, not to all establishments, 
but to small entities (defined as ``small business concerns'' by the 
Small Business Administration (SBA)) and also to very small entities 
(as defined by OSHA as small businesses with fewer than 20 employees). 
Second, although OSHA's regulatory flexibility screening test for 
revenues also uses a minimum threshold level of annualized costs equal 
to one percent of annual revenues, OSHA has established a minimum 
threshold level of annualized costs equal to five percent of annual 
profits for the average small entity or very small entity (rather than 
the ten percent threshold applicable for general economic feasibility 
screening). The Agency has chosen a lower minimum threshold level for 
the profitability screening analysis and has applied its screening 
tests to both small entities and very small entities in order to ensure 
that certification will be made, and an FRFA will not be prepared, only 
if OSHA can be highly confident that a final rule will not have a 
significant economic impact on a substantial number of small entities 
or very small entities in any affected industry.
    OSHA has prepared separate regulatory flexibility screening tests 
for general industry, maritime, and construction.
2. Impacts in General Industry and Maritime
    In this section, OSHA will determine whether (1) the rule is 
economically feasible for all affected industries in general industry 
and maritime, and (2) the Agency can certify that the rule will not 
have a significant economic impact on a substantial number of small 
entities in general industry and maritime. OSHA concludes that the rule 
is economically feasible, but the Agency is unable to certify that it 
will not have a significant economic impact on a substantial number of 
small entities.

[[Page 16535]]

a. Economic Feasibility Screening Analysis: All Establishments
    Earlier chapters of the FEA identified the general industry and 
maritime sectors potentially affected by the final rule; presented 
summary profile data for affected industries, including the number of 
affected entities and establishments, the number of at-risk workers, 
and the average revenue for affected entities and establishments; and 
developed estimates, by affected industry, of the costs of the rule. 
The economic impacts of the final rule on general industry and maritime 
are driven, in part, by the costs of additional dust control measures, 
respirators, and silica program activities needed to comply with the 
rule.
    To determine whether the final rule's projected costs of compliance 
would threaten the economic viability of affected industries; OSHA 
first compared, for each affected industry, annualized compliance costs 
to annual revenues and profits per (average) affected establishment. 
The results for all affected establishments in all affected industries 
in general industry and maritime are presented in Table VII-18, using 
annualized costs per establishment for the PEL of 50 [mu]g/m\3\. Shown 
in the table for each affected industry are total annualized costs, the 
total number of affected establishments, annualized costs per affected 
establishment, annual revenues per establishment, the profit rate, 
annual profits per establishment, annualized compliance costs as a 
percentage of annual revenues, and annualized compliance costs as a 
percentage of annual profits.
    The annualized costs per affected establishment for each affected 
industry were calculated by distributing the industry-level 
(incremental) annualized compliance costs among all affected 
establishments in the industry, where annualized compliance costs 
reflect a three percent discount rate. The annualized cost of the rule 
for the average establishment in all of general industry and maritime 
is estimated to be $4,939 in 2012 dollars. It is clear from Table VII-
18 that the estimates of the annualized costs per affected 
establishment in general industry and maritime vary widely from 
industry to industry. These estimates range from $220,558 for NAICS 
213112 (Support Activities for Oil and Gas Operations) and $57,403 for 
NAICS 331511 (Iron Foundries) to $304 for NAICS 621210 (Offices of 
Dentists) and $377 for NAICS 324121 (Asphalt Paving Mixture and Block 
Manufacturing).
    Table VII-18 also shows that, within the general industry and 
maritime sectors, there are no industries in which the annualized costs 
of the final rule exceed 1 percent of annual revenues and there are 
eight industries in which the annualized costs of the rule exceed ten 
percent of annual profits and none where annualized costs exceed one 
percent of annual revenues. NAICS 213112 (Support Activities for Oil 
and Gas Operations), has the highest cost impact as a percentage of 
revenues, of 0.56 percent. NAICS 327120 (Clay Building Material and 
Refractories Manufacturing) has the highest cost impact as a percentage 
of profits, of 31.08 percent. For all affected establishments in 
general industry and maritime, the estimated annualized cost of the 
rule is, on average, equal to 0.06 percent of annual revenue and 2.43 
percent of annual profits.
    The industries with costs that exceed ten percent of profits are: 
NAICS 327110--Pottery, Ceramics, and Plumbing Fixture Manufacturing, 31 
percent; NAICS 327120--Clay Building Material and Refractories 
Manufacturing, 31 percent; NAICS 327991--Cut Stone and Stone Product 
Manufacturing, 24 percent; NAICS 327390--Other Concrete Product 
Manufacturing, 17 percent; NAICS 327999--All Other Miscellaneous 
Nonmetallic Mineral Product Manufacturing, 16 percent; NAICS 327332--
Concrete Pipe Manufacturing, 13 percent; NAICS 327331 Concrete Block 
and Brick Manufacturing, 13 percent; and NAICS 327320 Ready-Mix 
Concrete Manufacturing, 10 percent.
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BILLING CODE 4510-26-C
b. Normal Year-to-Year Variations in Prices and Profit Rates
    The United States has a dynamic and constantly changing economy in 
which an annual percentage changes in industry revenues or prices of 
one percent or more is common. Examples of year-to-year changes in an 
industry that could cause such variations in revenues or prices include 
increases in

[[Page 16545]]

fuel, material, real estate, or other costs; tax increases; and shifts 
in demand.
Methodology
    To demonstrate the normal year-to-year variation in prices for all 
the manufacturers in general industry and maritime affected by the 
rule, OSHA developed in the FEA year-to-year producer price indices and 
year-to-year percentage changes in producer prices, by industry, for 
the years 2004 through 2014. As shown in Table VI-3 in the FEA, for the 
combined affected manufacturing industries in general industry and 
maritime over the 12-year period, the average change in producer prices 
was 2.7 percent a year. For the industries in general industry and 
maritime with the largest estimated potential annual cost impact as a 
percentage of revenue--NAICS 213112--Support Activities for Oil and Gas 
Operations, 0.56 percent; and NAICS 327991--Cut Stone and Stone Product 
Manufacturing, 0.42 percent--the average annual changes in producer 
prices in these industries over the 12-year period were, respectively, 
3.8 percent, and 0.5 percent.
    Based on these data, it is clear that the potential cost impacts of 
the final rule in general industry and maritime are all well within 
normal year-to-year variations in prices in those industries. The 
maximum cost impact of the rule as a percentage of revenue in any 
affected industry is 0.56 percent, while the average annual change in 
producer prices for affected industries was 2.7 percent for the period 
2004 through 2014 (changed from 1998 to 2009 in the PEA). Furthermore, 
even a casual examination of Table VI-3 of the FEA reveals that annual 
changes in producer prices in excess of five or even ten percent are 
possible without threatening an industry's economic viability. Thus, 
OSHA concludes that the potential price impacts of the final rule would 
not threaten the economic viability of any industries in general 
industry and maritime.
    Changes in profit rates are also subject to the dynamics of the 
U.S. economy. A recession, a downturn in a particular industry, foreign 
competition, or the increased competitiveness of producers of close 
domestic substitutes are all easily capable of causing a decline in 
profit rates in an industry of well in excess of ten percent in one 
year or for several years in succession.
    To demonstrate the normal year-to-year variation in profit rates 
for all the manufacturers in general industry and maritime affected by 
the rule, OSHA in the FEA developed Table VI-4 and Table VI-5, which 
show, respectively, year-to-year profit rates and year-to-year 
percentage changes in profit rates, by industry, for the years 2000 
through 2012. For the combined affected manufacturing industries in 
general industry and maritime over the thirteen-year period, OSHA 
calculated an average change in profit rates of 138.5 percent a year 
(average for all industries calculated from the per-NAICS averages 
shown in Table VI-5 in the FEA). For the industries in general industry 
and maritime with the largest estimated potential annual cost impacts 
as a percentage of profit--NAICS 327120--Clay Building Material and 
Refractories Manufacturing, 31 percent; NAICS 327110--Pottery, 
Ceramics, and Plumbing Fixture Manufacturing, 31 percent; and NAICS 
327991--Cut Stone and Stone Product Manufacturing, 24 percent--the 
average annual percentage changes in profit rates in these industries 
over the 13-year period were, respectively, 951 percent, 951 percent, 
and 113 percent.
    One complicating factor is that the annualized costs of the rule, 
if absorbed in lost profits, would involve not just a temporary loss of 
profits but a longer term negative effect on profits relative to the 
baseline. To address this issue, the Agency compared the effect of a 
longer term reduction in profits to much larger reductions in profits 
but over shorter periods. Assuming a three-percent discount rate, the 
Agency determined a ten percent decline in profit rates relative to the 
original baseline, which remains constant at that lower level over a 
ten-year period, would be equivalent to: \57\
---------------------------------------------------------------------------

    \57\ Note that the reduction in profits rates over time, as a 
result of the rule, is being measured here relative to the baseline. 
If the reduction in profit rates were made relative to the previous 
year, as is done in Table VI-5 in the FEA, then there would be only 
a one-time reduction in the profit rate in year one as a result of 
the rule, after which the profit rate would reach a new (lower) 
level but would not change from year to year.
---------------------------------------------------------------------------

     An 88.5 percent decline in profit rates for one year;
     a 44.5 percent decline in profit rates that remains 
constant at the lower level for two years; or
     a 30 percent decline in profit rates that remains constant 
at the lower level for three years.\58\
---------------------------------------------------------------------------

    \58\ Assuming a seven-percent discount rate, a ten-percent 
decline in profit rates over the ten-year annualization period would 
be equivalent to: A 75-percent decline in profit rates for one year; 
a 39-percent decline in profit rates that remains constant at the 
lower level for two years; or a 27-percent decline in profit rates 
that remains constant at the lower level for three years.
---------------------------------------------------------------------------

    An examination of Table VI-5, for the thirteen year period from 
2000 to 2012, clearly shows that short-run changes in average industry 
profit rates of the above magnitudes have occurred on numerous 
occasions in general industry and maritime, without threatening the 
economic viability of the affected industries. For this reason, OSHA is 
confident that potential profit rate impacts of ten percent or less as 
a result of the rule would not threaten the economic viability of the 
affected industries in general industry and maritime.
    A longer-term loss of profits in excess of ten percent a year could 
be more problematic for some affected industries and might conceivably, 
under sufficiently adverse circumstances, threaten an industry's 
economic viability. In OSHA's view, however, affected industries would 
generally be able to pass on most or all of the costs of the final rule 
in the form of higher prices rather than bear the costs of the final 
rule in reduced profits. In other words, the demand for the goods and 
services produced by affected industries in general industry and 
maritime do not appear to be perfectly elastic or close to it. While 
there are substitutes for these products, there are no perfect 
substitutes that would lead the price elasticity to be extremely high. 
As a result, the demand for quantities of brick and structural clay, 
vitreous china, ceramic wall and floor tile, other structural clay 
products (such as clay sewer pipe), and the various other products 
manufactured by affected industries would not significantly contract in 
response to a 0.48 percent (or lower) price increase for these 
products. It is of course possible that such price changes will result 
in some reduction in output, and the reduction in output might be met 
through the closure of a small percentage of the plants in the 
industry. However, the only realistic circumstance under which an 
entire industry would be significantly affected by small price 
increases would be the availability in the market of a very close or 
perfect substitute product not subject to OSHA regulation. The classic 
example, in theory, would be foreign competition. In the following 
discussion OSHA examines the threat of foreign competition for affected 
U.S. establishments in general industry and maritime and concludes that 
it is unlikely to threaten the viability of any affected industry.
Public Comments on Year-to-Year Variations in Prices and Profit Rates
    The American Chemistry Council (ACC) stated, with respect to a 
similar analysis in the PEA, that short-term volatility within an 
industry sector is of little value in projecting what will

[[Page 16546]]

happen when a new regulation resets the baseline for profits and 
revenue because OSHA is comparing short-term changes to long-term 
changes (Document ID 2307, Attachment 2, p. 196). Another commenter 
made the similar point that year-to-year fluctuations cannot be 
compared to long-term changes (Document ID 2308, Attachment 9, p. 7).
    OSHA first examines the issue of changes in prices over time. Such 
changes, on the whole, represent pass through of changes in costs, 
since profits are not continually rising. These changes in costs are 
not ``fluctuations'' with upward and downward shifts in prices. For 
almost all industries these changes in costs are continuing upward 
shifts that average each year much larger changes than the maximum 
price change any industry will need to incur in order to comply with 
the silica rule.
    For variations in profits, these are indeed fluctuations and 
profits do indeed both rise and fall. However, if, as the commenters 
argue only long-term average profits matter, then we could reach the 
very counterintuitive result that there should be no excess plant 
closures during recessions. This is not the case because long-term 
profits are, in fact, nothing more than a prediction and the present 
value of long term profits will be different at the beginning than at 
the end of a recession. Recognizing these timing effects is why OSHA 
examined the annualized value of losses in profits associated with the 
recession beginning 2008 and compared it to the annualized value of the 
loss in profits as result of costs of this standard. While temporary 
and permanent losses are different, the use of discounting enables us 
to compare short- and long-term losses.
c. International Trade Effects
    The magnitude and strength of foreign competition is an important 
factor in determining the ability of firms in the U.S. to pass on (part 
or all of) the costs of the rule in the form of higher prices for their 
products. If firms are unable to do so, they must absorb the costs of 
the rule out of profits, possibly resulting in the business failure of 
individual firms or even, if the cost impacts are sufficiently large 
and pervasive, causing significant dislocations within an affected 
industry.
    As in the PEA, OSHA in the final economic analysis examined how 
likely such an outcome is. The analysis there included a review of 
trade theory and empirical evidence and the estimation of impacts. 
Throughout, the Agency drew on ERG (2007c) (Document ID 1710), which 
was prepared specifically to help analyze the international trade 
impacts of OSHA's final silica rule. A summary of the FEA results is 
presented below.
    OSHA focused its analysis on eight of the industries likely to be 
most affected by the final silica rule and for which import and export 
data were available. OSHA combined econometric estimates of the 
elasticity of substitution between foreign and domestic products, 
Annual Survey of Manufactures data, and assumptions concerning the 
values for key parameters to estimate the effect of a range of 
hypothetical price increases on total domestic production. In 
particular, OSHA estimated the domestic production that would be 
replaced by imported products and the decrease in exported products 
that would result from a 1 percent increase in prices--under the 
assumption that firms would attempt to pass on all of a 1 percent 
increase in costs arising from the final rule. The sum of the increase 
in imports and decrease in exports represents the total loss to 
industry attributable to the rule. These projected losses are presented 
as a percentage of baseline domestic production to provide some context 
for evaluating the relative size of these impacts.
    The effect of a 1 percent increase in the price of a domestic 
product is derived from the baseline level of U.S. domestic production 
and the baseline level of imports. The baseline ratio of import values 
to domestic production for the eight affected industries ranges from 
0.04 for iron foundries to 0.547 for ceramic wall and floor tile 
manufacturing--that is, baseline import values range from 4 percent to 
more than 50 percent of domestic production in these eight industries. 
OSHA's estimates of the percentage reduction in U.S. production for the 
eight affected industries due to increased domestic imports (arising 
from a 1 percent increase in the price of domestic products) range from 
0.013 percent for iron foundries to 0.237 percent for cut stone and 
stone product manufacturing.
    OSHA also estimated the baseline ratio of U.S. exports to 
consumption in the rest of the world for the sample of eight affected 
industries. The ratios range from 0.001 for other concrete 
manufacturing to 0.035 percent for nonclay refractory manufacturing. 
The estimated percentage reductions in U.S. production due to reduced 
U.S. exports (arising from a 1 percent increase in the price of 
domestic products) range from 0.014 percent for ceramic wall and floor 
tile manufacturing to 0.201 percent for nonclay refractory 
manufacturing.
    The total percentage change in U.S. production for the eight 
affected industries is the sum of the loss associated with increased 
imports and the loss resulting from reduced exports. The total 
percentage reduction in U.S. production arising from a 1 percent 
increase in the price of domestic products range from a low of 0.085 
percent for other concrete product manufacturing to a high of 0.299 
percent for porcelain electrical supply manufacturing.
    These estimates suggest that the final rule would have only modest 
international trade effects. It was previously hypothesized that if 
price increases resulted in a substantial loss of revenue to foreign 
competition, then the increased costs of the final rule would have to 
come out of profits. That possibility has been contradicted by the 
results reported in this section. The maximum loss to foreign 
competition in any affected industry due to a 1 percent price increase 
was estimated at approximately 0.3 percent of industry revenue. 
Because, as reported earlier in this section, the maximum cost impact 
of the final rule for any affected industry would be 0.56 percent of 
revenue, this means that the maximum loss to foreign competition in any 
affected industry as a result of the final rule would be 0.2 percent of 
industry revenue --which would hardly qualify as a substantial loss to 
foreign competition. This analysis cannot tell us whether the resulting 
change in revenues will lead to a small decline in the number of 
establishments in the industry or slightly less revenue for each 
establishment. However it can reasonably be concluded that revenue 
changes of this magnitude will not lead to the elimination of 
industries or significantly alter their competitive structure.
    Based on the Agency's preceding analysis of economic impacts on 
revenues, profits, and international trade, along with the discussion 
of industry concerns below, OSHA concluded that the annualized costs of 
the final rule are below the threshold level that could threaten the 
economic viability of any industry in general industry or maritime. 
OSHA further noted that while there would be additional costs (not 
attributable to the final rule) for some employers in general industry 
and maritime to come into compliance with the new silica standard, 
these costs would not affect the Agency's determination of the economic 
feasibility of the final rule.

[[Page 16547]]

Public Comment on International Trade Effects
Foundries
    The following comments discuss the loss of business to foreign 
competition in the foundry industry. The comments have been grouped 
together by issue and are followed by OSHA's response. The first group 
of commenters used impact numbers from an alternative cost model to 
discuss the loss of business to foreign competition.
    The United States Chamber of Commerce (``the Chamber'') stated that 
additional costs of the rule's ancillary provisions along with 
engineering controls will result in reduced competitiveness relative to 
foreign foundries (Document ID 2288, pp. 27-28). The Chamber also 
critiqued OSHA's inability to determine feasibility because of a lack 
of data to analyze economic impacts across facilities by age, design, 
operations, condition and region (Document ID 2288, pp. 29-30).
    In the comments above, the negative economic effect of losing 
business to foreign competition is based on an alternative cost model 
report prepared for the American Foundry Society (AFS) by Environomics. 
This report is addressed in the Engineering Control Costs section in 
Chapter V of the FEA, where OSHA concluded that the costs in that 
report were inflated. Because these inflated costs also underpin the 
Chamber's claim that the rule will reduce competitiveness with foreign 
foundries, OSHA does not accept that claim. In response to the 
Chamber's criticism of OSHA's data sources, the Agency notes that 
Chapter III, the section on Survey Data and OSHA Economic Analyses, 
discusses why it was infeasible to collect and compile a full-scale 
national survey of the kinds of baseline conditions and practices that 
the Chamber of Commerce urged OSHA to consider.
    The following comments from foundry firms and associations address 
foreign competition in metalcasting from China and India along with the 
inability to pass the cost on to their customers.
    AFS submitted comments that the metalcasting industry would lose 
business to foreign competition as follows:

    Many foundries have closed in recent years with foreign 
competition assuming much of that business. Five of the eleven 
identifiable foundries used in the PEA to support OSHA's assertion 
of feasibility have closed. Because castings are the starting point 
of many manufacturing processes, loss of foundry jobs also means 
loss of other manufacturing jobs.
    The U.S. metalcasting industry is made up of 1,978 facilities, 
down from 2,170 five years ago. This reduction can be attributed to 
the recession, technological advancements, foreign competition and 
tightening regulations (Document ID 2379, Attachment 3, p. 42; 4035, 
p. 5).

    The Indiana Cast Metals Association concurred with these comments 
and also suggested that other industries would also be negatively 
impacted if U.S. foundries shut down (Document ID 2049, p. 1). The Ohio 
Cast Metals Association submitted two comments stating that the rule 
will increase costs and undermine the Ohio-based metalcasting 
industry's ability to compete in the global marketplace:

    [The silica rule] will significantly increase costs, slow down 
or eliminate hiring, reduce the number of foundry jobs and undermine 
our industry's ability to compete in the global marketplace. For 
some foundries, the rulemaking could be the final straw that 
destroys their business.
    . . . Over the past two decades Ohio foundries along with other 
manufacturers throughout the United States have faced tremendous 
international competition from China, Brazil, and India and many 
foundries have closed and thousands of employees have lost their 
jobs during this period. To suggest that Ohio foundries can just 
pass on the tremendous costs associated with compliance with the 
proposed silica rule with ``minimal loss of business to foreign 
competition'' indicates that the individuals performing this 
analysis were driven by other agendas or misinformed (Document ID 
2119, Attachment 3, pp. 1-2).

    Grede Holdings L.L.C. submitted a comment expressing its view that 
it would be difficult for foundries to pass the cost of compliance to 
the customer because of international competition, and that the number 
of foundries in the U.S. has dropped by more than half since 1980, 
going from 4,200 foundries to 2,050 foundries (Document ID 2298, p. 3).
    Sawbrook Steel submitted two comments voicing concern that the 
implementation of the regulation will cause jobs to move overseas, 
resulting in a shrinking of the domestic casting manufacturing 
(Document ID 2227, p. 2; 1995, p. 1).
    In the comments above, businesses and associations state that the 
costs of the rule will be too high and they will lose business to 
foreign competition. The chief advantage of foreign imports to 
downstream users, as reported to the U.S. International Trade 
Commission (ITC) during an investigation they conducted into the 
competitive conditions in the U.S. foundry market, is their low 
pricing. Respondents to the investigations said the cost of foreign 
produced products ranged from ten percent to forty percent less than 
the cost of U.S. products (Document ID 0753, table 5-60, p. 5-53 as 
referenced in Document ID 1710, pp. 5-4). U.S. producers have responded 
to competition with a broad array of initiatives, such as implementing 
lean manufacturing, improving customer service, and increasing 
automation (Document ID 0753, pp. 10-14 and 10-15). According to the 
ITC study:

    The use of technology may also be influenced by the type of 
castings produced and relative wage rates. Low-value, low-quality 
castings, for example, generally require a lower level of technology 
and relatively more semi-skilled labor than foundries producing more 
complex castings. To lower labor costs, foundries in developed 
countries with higher wage rates may install more automation and 
technological improvements, whereas foundries in developing 
countries with relatively lower wage rates may substitute labor for 
relatively high-cost capital investments (Document ID 0753, p. 2-
11).

    Before addressing issues on international competition for 
metalcasters, it should be noted that all foundry industries affected 
by this rule are below the ten percent cost to profit threshold and one 
percent cost to revenue threshold. This means that even if the argument 
that costs cannot be passed on were to be correct, the loss in profits 
would be less than ten percent and unlikely to effect the feasibility 
of the industry. Further the costs to be passed on would require less 
than one percent price increases. In general, metalcasters in the U.S. 
have shortened lead times, improved productivity through computer 
design and logistics management, provided expanded design and 
development services to customers, and provided a higher quality 
product than foundries in China and other nations where labor costs are 
low (Document ID 0753, p. 3-12). All of these measures, particularly 
the higher quality of many U.S. metalcasting products and the ability 
of domestic foundries to fulfill orders quickly, are substantial 
advantages for U.S. metalcasters that may outweigh the very modest 
price increases projected in Tables VI-3 and VI-4 of the FEA (Document 
ID 1710, p. 5-4). According to the ITC study, quality was the number 
one purchasing decision factor for the majority of purchasers, with 
price and lead times ranking lower, and U.S. metalcasters are able to 
deliver that quality (Document ID 0753, p. 4-5). The ITC report noted:

    Certain purchasers noted that when inventory management and 
complex manufacturing skills are required, U.S. foundries excel. 
U.S. foundries were also cited by responding U.S. purchasers as 
manufacturing with a low defect (rejection) rate. (Id.)


[[Page 16548]]


    Purchaser responses to the ITC's survey stated that some U.S. 
foundries are also completely inoculated against foreign competition, 
even if the prices of U.S. foundry products rise:

    As noted in questionnaire responses, certain purchasers are 
committed to buying solely U.S.-made castings. One U.S. foundry 
official noted that if downstream customers require castings to be 
made in the United States, then U.S. foundries are guaranteed that 
business. This situation often occurs when foundries supply castings 
for federally funded operations, such as construction projects 
(Document ID 0753, p. 4-5).

    Foundries in China and India, while expanding their capacities, are 
also faced with rising domestic demand due to their own rapidly 
expanding domestic industrial economies, which affect their ability to 
fulfill export demand (Document ID 0753, p. 5-16). ERG's research noted 
a growth in U.S. foundry exports, which could help to offset some of 
the foreign imports entering the U.S. market. According to one report 
cited by ERG, U.S. foundry exports were roughly equivalent to 53 
percent of the imports (Document ID 1710, p. 5-5).
    ERG's research also provided some evidence that the combination of 
U.S. and foreign demand for metalcasting may outstrip the supply to 
such a degree that, even if the U.S. foundries operated at full 
capacity, their maximum output would fail to meet the demand from the 
U.S. and foreign markets (Document ID 1710, p. 5-5). The U.S. foundry 
industry is unlikely to face any significant economic impacts if there 
is ample demand and a limited supply because such a condition makes it 
easier to pass along any costs of the rule.
Tile Production
    The following comments discuss the difficulties of competing with 
foreign tile producers followed by OSHA's response.
    Tile Council of North America (TCNA) noted the import price 
sensitivity between domestic tile and imported tile as follows:

    The low cost of imported tile places an enormous burden on U.S. 
tile manufacturers to maintain current pricing to remain 
competitive. According to the latest data collected by TCNA, the 
average price per square foot of U.S. tile shipments is $1.43. The 
average price per square foot of Chinese imports is $0.86. With 
Chinese imports 60% less expensive than U.S. tile in what is an 
extremely price-competitive market, OSHA's claim that ``any price 
increases would result in minimum loss of business to foreign 
competition'' strains credulity.
    To illustrate the tremendous import/price sensitivity between 
domestic tile and imports, we note the increase in imports from Peru 
as a result of a bilateral free trade agreement between Peru and the 
United States eliminating duty on tile from Peru. Although only 
amounting to a price change of 4--5 cents per square foot, from 
2008, the year before the bilateral agreement to the end of 2011, 
tile imports from Peru into the United States grew by 59%. This 
illustrates how even a small change in price due to modest increases 
in operating costs and raw material costs pose an existential threat 
to the tile manufacturing industry.
    The import sensitivity of domestic tile manufacturing operations 
is well known by the United States International Trade Commission 
(USITC) and the office of the United States Trade Representative 
(USTR). The assertion made by OSHA that cost increases will not 
result in lost market share to foreign competition is in direct 
conflict with information known by USITC and the USTR and contrary 
to established public policy (as reflected in existing Free Trade 
Agreements) and industry testimony.
    Contrary to the assertion made by OSHA, the marginal price 
increases anticipated by required conformance to the rule as 
proposed would make the domestic tile manufacturing industry highly 
uncompetitive threatening the very viability of this import-
sensitive industry (Document ID 2363, p. 9).

    The National Tile Contractors Association also questioned OSHA's 
preliminary determination that the tile industry could pass on most or 
all costs through higher prices, calling the claim ``wildly 
erroneous'':

    Implementation of the proposed rule's requirements would 
increase both production and installation costs, and would put 
pressure on consumer prices. At a time when U.S. consumption of 
ceramic tile is more than 25% below its peak level (2006), this is a 
serious concern. The U.S. market is already flooded with lower 
quality, lower priced imports from many countries that likely do not 
respect the health, safety, and rights of workers. The low cost of 
imported tile places an enormous burden on U.S. tile manufacturers 
to maintain current pricing to remain competitive (Document ID 2267, 
p. 8).

    Dal-Tile echoed the TCNA comments regarding the inability to pass 
costs onto the customer (Document ID 2147, p. 3).
    OSHA does not dispute the commenters' information indicating that 
Chinese and Peruvian tile are significantly cheaper than U.S. tile, but 
that point actually undercuts their claim that a small change in the 
price of U.S. tile would place an ``enormous burden'' on U.S. tile 
manufacturers. The commenters note that Chinese tile is already 
available in the U.S. at just over half the price of U.S. tile. If the 
market was actually as sensitive as the commenters suggest, and the 
Chinese tile was competing for the same market share as U.S. tile, 
under the commenter's logic the U.S. tile industry would have already 
gone out of business. But that has not happened, suggesting that U.S. 
tile manufacturers have been able to identify customers for whom the 
tile price is not the predominant factor. Likewise, the example of 
Peruvian tile demonstrates only that the lower-priced imported tile is 
sensitive to small price changes. The commenter provides no evidence 
that the Peruvian tile is competing for the same customers as the U.S. 
tile industry.
    In summary, the TCNA's argument that cost increases will result in 
lost market share to foreign competition is unconvincing because it is 
not clear that there is a strong relationship between the price of the 
foreign tile and the price of the U.S. tile. One likely cause for this 
disconnect is that, as TCNA notes, the market is ``already flooded with 
lower quality, lower priced'' imports (Document ID 2363, p. 8), 
suggesting that tile from China, Peru, and the other lower-priced 
foreign importers are of a lower quality that may be targeted at a 
different customer base than the higher-quality U.S. tile. This 
perception that tile from China and other low-cost tile producing 
countries may be of lower quality produces an imperfect substitution 
scenario and adds to the inelasticity of demand for domestic tiles, 
enabling producers to pass some of the costs on to the consumer.
    On the other end of the tile price range are the Italian tiles. 
Italy and China are the top countries of origin for tiles imported into 
the U.S., but tiles from these countries command very different prices. 
In terms of general tile products, one source indicates that the 
average prices of tiles imported by the U.S. in 2012 were $20.20 to 
$20.90 per square meter for Italian tiles and between $8.30 and $8.70 
per square meter for Chinese tiles imported by the U.S., a significant 
price difference that could be explained by a difference in 
quality.\59\ TCNA stated above that the average price of tile from 
China is $0.86 per square foot or $9.25 (10.76 x 0.86) per square 
meter. TCNA's average price of American tile is $1.43 per square foot 
or $15.39 (10.76 x 1.43) per square meter (Document ID 2363, p. 9), 
which shows the U.S. producers to be supplying a mid-priced product. 
Although Italy is also a major source of tile imports in the U.S. 
despite their higher price, the commenters did not suggest that an 
increase in U.S. tile prices would cause the U.S. to lose market share 
to the Italian tile; nor did the commenters suggest that lower-priced 
U.S. tile could be exported to dominate the Italian market. The 
implication is, again, that different

[[Page 16549]]

customers are willing to pay different prices for different quality 
tile.
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    Using price as an indicator of quality, the tile market can be 
segmented into three categories: Low quality, mid-grade, and high 
quality. The U.S. tile industry has located a niche between the lowest 
quality/lowest priced tile and the highest quality/highest priced tile. 
While it is possible that a few tile firms that produce very low-
quality or very high-quality tile may be negatively impacted by an 
increase in the price of their tile, OSHA concludes that the majority 
of firms would not experience a significant negative economic impact. 
This is along with the fact that the increase in price from this rule 
is expected to be minimal. TCNA commented that the average price per 
square foot of U.S. tile shipments is $1.43. The cost to revenue ratio 
for NAICS 327122 Ceramic Wall and Floor Tiles is 0.35 percent, meaning 
this final rule will increase the average cost of U.S. tile by five 
hundredths of a cent (or $0.0005 per square foot). It is therefore fair 
to say this extremely modest increase in the average price of U.S. tile 
would not have a significant economic impact on the U.S. tile industry 
as a whole.
Brick Industry
    During the public hearing Belden Tri-State Building Materials 
stated that the brick industry has foreign competition, mostly from 
Canada, and some from Mexico (particularly in Texas, Oklahoma or 
Arkansas), and Germany (Document ID 3586, Tr. 3457). They indicated 
that their competition includes not only imported brick but also 
``other cladding materials like vinyl siding and HardiePlank,'' but the 
competition from imported brick is typically ``more expensive brick'' 
because of ``innovations in Europe that we just haven't caught up to, 
different sizes, different colors, different processes'' (Id.).
    Acme Brick Company representatives indicated in testimony that 
oversees competition was virtually nonexistent because it is ``hard to 
get that across the ocean economically'' and noted that they generally 
locate their production facilities strategically to be near their 
markets because ``[p]roduction costs really are about a third of the 
cost of the brick when we have them close . . . [The] farther away [the 
bricks come from]--there are some distinctions in the quality or the 
makeup of a brick'' (Document ID 3577, Tr. 736).
    This testimony indicates to OSHA that international competitors 
will not be able to take advantage of any potential price increases 
made by U.S. producers in the U.S. domestic brick market. The brick 
making industry will therefore be able to pass on most, if not all, of 
the costs of complying with the rule.
Hydraulic Fracturing
    To determine the economic impacts for most industries, OSHA used 
the Census Bureau's Statistics of U.S. Businesses to estimate revenues 
on a six-digit NAICS basis but these revenue data were not sufficiently 
precise to isolate the hydraulic fracturing component from the larger 
industry (NAICS 213112). As a result, instead of using data from the 
Economic Census, revenues for hydraulic fracturing firms were based on 
estimated utilization rates and per stage revenues. As discussed in 
Chapter III of the FEA, Profile of Affected Industries, the data on 
this industry have been updated to reflect the comments in the record 
and the best data available in 2012. The cost to profit percentage for 
the hydraulic fracturing industry estimated in the FEA is 7.67 percent 
(below OSHA's ten percent threshold) for fleets of all sizes. The ratio 
of costs to revenues for hydraulic fracturing firms in the FEA is 
estimated to be 0.54 percent for all establishments in the industry, 
0.17 percent for small entities and 0.24 percent for very small 
entities. Although the costs as a percent of revenue increased for all 
establishments, the impacts still remain well below the one percent 
threshold.
    However, these estimates are based on the state of the industry in 
the base year of 2012 supplemented with data provided in comments to 
the proposed rule in 2013 and early 2014. When the PEA was published in 
2006, the price of oil fluctuated between $70 and $80 a barrel. During 
the years following the publication of the PEA the price of oil has had 
some large fluctuations. Before the recession of 2008 the price of oil 
peaked at $146 per barrel but dropped to $44 dollars per barrel during 
the economic downturn in 2008.\60\ As the price of oil steadily 
increased during 2009, there was an influx of money invested in the 
hydraulic fracturing industry. The FEA uses revenue data from 2012 when 
the price per barrel fluctuated between $90 and $100. However, in the 
fourth quarter of 2014, the price of oil dropped to $49 per barrel. The 
price of oil in 2015 has oscillated between approximately $45 and $60 
per barrel.\61\ Because of this major change in the industry since the 
record closed in 2012, OSHA has supplemented its feasibility analysis 
with more current data.
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The Structure of the Hydraulic Fracturing Industry
    Hydraulic fracturing nearly doubled U.S. oil production from 5.6 
million barrels a day in 2010 to a rate of 9.3 million barrels a day in 
2015. Up until the drop in oil prices during the fourth quarter of 
2014, the expected annual increase in production was one million 
barrels. The economics of hydraulic fracturing wells is much different 
than conventional wells.\62\ The marginal cost of producing a barrel of 
oil from a conventional well for large oil producing countries is 
around $15 to $30.\63\ Therefore, the owners of conventional wells 
continue to produce even as the price per barrel decreased from $100 to 
$40, and would remain in business at costs down to $30. The traditional 
oil drilling business is driven by marginal costs, not costs spent to 
drill the well. This means that supply is inelastic relative to demand. 
This has not been true for the hydraulic fracturing industry.
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    Hydraulic fracturing wells have a very short life compared to 
conventional wells. For example, a well in the Bakken region straddling 
Montana and North Dakota may start out producing 1,000 barrels a day 
then decline to 280 barrels at the beginning of year two. By year 
three, more than half of the reserves will be depleted. Therefore, to 
generate revenue, producers need to constantly drill new wells. In this 
sense, hydraulic fracturing wells are more like gold or silver mines 
than conventional oil production.\64\ The recent drop in oil prices has 
caused a series of bankruptcies and closures across the oil industries. 
Although there was a reduction in the number of rigs from about 1,600 
to 800,\65\ hydraulic fracturing still accounted for 4.6 million 
barrels a day out of a total of 9.4 million barrels or 49 percent of 
total oil produced in February 2015. Hydraulic fracturing also 
accounted for 54 percent of natural gas output.
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    \65\ http://www.economist.com/node/21648622/print.
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    The Energy Information Administration (EIA) projects the Brent 
crude oil price will average $40 a barrel in 2016 and $50 a barrel in 
2017. However, EIA expects crude oil prices

[[Page 16550]]

to rise in future years, rising to over $70 per barrel by 2020 and to 
$100 per barrel by 2028. EIA's crude oil price forecast remains subject 
to significant uncertainties as the oil market moves toward balance and 
could continue to experience periods of heightened volatility.\66\ 
Thus, industry implementation of OSHA's engineering control 
requirements, which are not required until five years after the 
effective date of the rule, may come during a period of much higher and 
rising energy prices. In any case, the price increase required by this 
rule is a very small fraction of the fluctuation in energy prices 
during the past several years.
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    However, the possibility that oil prices are not going to increase 
in the near future has spurred a new wave of innovation in energy 
exploration. Now that prices have dropped to around $50 a barrel, 
companies are focusing on efficiency and getting the most petroleum for 
the least amount of money. With the effective date of this rule on the 
horizon, it is possible that some of this innovation will lead to 
technologies that not only increase efficiency but reduce worker 
exposures to silica at the same time.
    Through the application of new technology OSHA believes that, even 
in a lower price environment, hydraulic fracturing entrepreneurs will 
be able to implement the controls required by this final rule without 
imposing significant costs, causing massive economic dislocations to 
the hydraulic fracturing industry, or imperiling the industry's 
existence. Big oil-field-services like Haliburton Co. and Schlumberger 
Ltd. report that they have witnessed customers concentrating on using 
technology such as lasers and other high-tech equipment and data 
analytics before they drill to make sure new wells deliver the most 
crude for the investment cost. The application of this new technology 
as well as fiber-optic tools that help monitor a well during hydraulic 
fracturing to make sure that it's working as well as possible and new 
techniques to stimulate microbes already present that attach themselves 
to bits of oil, essentially breaking it up and making it easier for the 
crude to flow through rock \67\ have had positive quantitative results. 
Productivity at some ``super-fracking'' wells has increased 400-600 
barrels a day per rig from just a few years ago. Drilling efficiency in 
some areas has increased as much as 26 percent in a single year \68\ 
while the time to drill and fracture a well has come down from an 
average of 32 days in 2008 to now only about half that time: 14-16 days 
from start to finish and in some cases even less. These increased 
efficiencies result in significant cost savings.\69\ Also, the lower 
demand by hydraulic fracturing companies for equipment rental, 
trucking, and labor has caused a decrease in their prices, reducing the 
overall cost of hydraulic fracturing.\70\
---------------------------------------------------------------------------

    \67\ http://www.wsj.com/articles/oil-companies-tap-new-technologies-to-lower-production-costs-1442197712/.
    \68\ http://www.forbes.com/sites/judeclemente/2015/05/07/u-s-oil-production-forecasts-continue-to-increase/.
    \69\ http://www.aei.org/publications/top-10-things-i-learned-on-my-summer-trip-to-the-bakken-oil-fields-part-ii/.
    \70\ http://fortune.com/2015/01/09/oil-prices-shale-fracking/.
---------------------------------------------------------------------------

    Although the drop in the price of oil has caused an initial 
reduction in hydraulic fracturing operations, the application of 
recently developed technology to new wells has increased per well 
production. One expert was quoted in Fortune magazine as saying 
``[t]here tailing off in U.S. drilling activity, but I expect continued 
development drilling in major new areas, particularly the Bakken, even 
at $50 (a barrel).'' \71\ In the Bakken region in 2015 the decrease in 
oil production resulting from the reduction of rigs was substantially 
offset by increases in new well oil production per rig. There are 
reasons to believe in the continuance of tight oil growth. An analysis 
by IHS shows that most of the potential U.S. tight oil capacity 
additions in 2015 have a break-even price in the range of $50 to $69 
per barrel. Continued productivity gains, such as improvements in well 
completion and downspacing, also support the continuation of U.S. 
production growth at lower prices.\72\ Based on these advances, it is 
plausible that hydraulic fracturing shale operations may achieve break-
even costs of $5-$20 per barrel.\73\
---------------------------------------------------------------------------

    \71\ http://fortune.com/2015/01/09/oil-prices-shale-fracking/.
    \72\ http://press.ihs.com/press-release/energy-power/tight-oil-test-us-production-growth-remains-resilient-amid-lower-crude-oi.
    \73\ http://economics21.org/commentary/shale-2.0-big-data-revolution-america-oil-fields-05-20-2015.
---------------------------------------------------------------------------

    A sign of the ongoing effectiveness of upgrades in efficiency in 
the hydraulic fracturing business is evident in the projections for 
U.S. crude production. The EIA's Annual Energy Outlook for 2015 has 
projected that the U.S. is on track to hit reach a record for crude 
output at 10.6 million barrels a day in 2020.\74\
---------------------------------------------------------------------------

    \74\ http://www.forbes.com/sites/judeclemente/2015/05/07/u-s-oil-production-forecasts-continue-to-increase/.
---------------------------------------------------------------------------

    While the economic conditions faced by the hydraulic fracturing 
industry have changed significantly since the publication of the 
proposed rule, this discussion shows that there is significant reason 
to believe that this rule will not have a significant impact on the 
hydraulic fracturing industry. Advancements in technology and the 
application of new efficient drilling methods continue to increase the 
per-rig production capacity of new-well oil drilling rigs while 
lowering the costs of operating these rigs. These technological changes 
increase the energy recovered through hydraulic fracturing, and thus 
the value of fracturing services, without increasing the costs per well 
associated with controlling silica exposures. Further, the demand for 
fracturing services will depend, in part, on energy prices. The costs 
associated with complying with the silica rule are a minor issue by 
comparison. Thus, OSHA's conclusion that this rule is economically 
feasible for the hydraulic fracturing industry has not changed.
Railroads
    In the PEA, OSHA did not include any estimates of costs as 
percentage of revenues or as a percentage of profits for railroads. 
This was due to the fact that the standard sources of economic 
statistics that were used for data on revenues and employment for all 
other affected industries do not include railroads. The Association of 
American Railroads (AAR) expressed concern about the impact of the rule 
on small railroads (although not on larger railroads), but did not 
provide any estimates or analysis, or suggest that OSHA use any 
specific sources to conduct such an analysis. For the FEA, OSHA did 
examine costs as percentage of revenues and profits for the railroad 
industry as a whole using supplemental information from sources 
typically relied on by the industry.
    For the FEA, OSHA estimated that 16,895 workers in the rail 
transportation industry (NAICS 4821; ``railroads'') will be covered by 
the final standard, including 7,239 workers employed as Ballast Dumpers 
and 9,656 workers employed as Machine Operators (for the purposes of 
this analysis, OSHA assumed that the machine operators would be 
conducting at least some work outside of the cab of the equipment). The 
Agency estimated that compliance costs for railroads will total $16.6 
million, or $980 per affected worker.
    Based on these estimates, OSHA judged that the final rule is 
feasible for railroads because combining

[[Page 16551]]

supplemental data from BLS \75\ and the Association of American 
Railroads \76\ for the estimated 105 rail transportation establishments 
in NAICS 4821 with a reported revenue of $72.9 billion, the cost-to-
revenue impacts are an estimated 0.02 percent and cost-to-profit 
impacts are an estimated 0.4 percent. In addition, the per-worker cost 
for railroads ($980) is lower than the average per-worker cost ($1,231) 
across all affected NAICS industries in general industry and for 2000-
2012, the average profit rate for rail transportation, 6.2 percent, was 
significantly higher than the average profit rate for all affected 
NAICS industries throughout general industry (3.4 percent).
---------------------------------------------------------------------------

    \75\ Bureau of Labor Statistics, Quarterly Census of Employment 
and Wages, Series ID ENUUS0002054821, NAICS 4821, Rail 
Transportation. Accessed November 6, 2015.
    \76\ Railroad Statistics. Association of American Railroads. AAR 
Policy and Economics Department. July 15, 2014. http://www.aar.org/StatisticsAndPublications/Documents/AAR-Stats.pdf.
---------------------------------------------------------------------------

    The AAR noted that small railroads had not been covered in the 
Initial Regulatory Flexibility Analysis (Document ID 2366, p. 4). The 
commenter is correct that OSHA did not examine small entities in this 
sector but has done so for the FEA using supplemental information on 
railroads.
    In 2012, 574 U.S. freight rail establishments, employing 181,264 
workers, operated on roughly 169,000 miles of track.\77\ The Surface 
Transportation Board in the U.S. Department of Transportation 
classifies railroads into three groups based on annual revenues:
---------------------------------------------------------------------------

    \77\ Class I Railroad Statistics. Association of American 
Railroads. AAR Policy and Economics Department. July 15, 2014.
---------------------------------------------------------------------------

     Class I for freight railroads defined as railroads with 
annual operating revenues above $467.1 million ($2013)
     Class II, includes some regional railroads, defined as 
railroads each with operating revenues between $37.4 million and $467.1 
million ($2013)
     Class III for all other freight rail operations (including 
smaller regional, short-line, switching, and terminal).\78\
---------------------------------------------------------------------------

    \78\ Federal Register, Volume 79, No. 111, June 10,2014, p. 
33257, cited in Summary of Class II and Class III Railroad Capital 
Needs and Funding Sources--A Report to Congress, Federal Railroad 
Administration, October 2014, p. 2 http://www.fra.dot.gov/Elib/Document/14131.
---------------------------------------------------------------------------

    In 2013, in addition to the seven Class I freight railroad systems, 
there were 21 regional railroads (line-haul railroads operating at 
least 350 miles of road and/or earning revenue between roughly $40 
million and the Class I threshold), and over 500 local railroads (line-
haul or short-line railroads smaller than regional railroads).\79\ 
Among the 567 railroads that fell below the Class I revenue threshold, 
11 qualified as Class II and the remainder (556, including 10 regional 
railroads) qualified as Class III (FRA, 2015). Class III railroads are 
typically local short-line railroads serving a small number of towns 
and industries or hauling cars for one or more larger railroads. Many 
Class III railroads were once branch lines of larger railroads or 
abandoned portions of main lines.
---------------------------------------------------------------------------

    \79\ Freight Railroads Background. (FR, 2015) Stephanie 
Lawrence, Office of Policy, Office of Rail Policy and Development, 
Federal Railroad Administration April 2015. http://www.fra.dot.gov/eLib/Details/L03011. These regional railroads are almost evenly 
divided between Class II (11 railroads) and Class III (10 
railroads).
---------------------------------------------------------------------------

    In 2012, employment within 546 local railroad companies totaled 
12,293 workers and employment within 21 regional railroads totaled 
5,507 workers. Line Haul Railroads are classified in NAICS 482111 and 
entities within this industry with 1,500 or fewer workers are 
classified as small by SBA size standards. Local/Short Line Railroads 
are classified in NAICS 482112 and entities within this industry with 
500 or fewer workers are classified as small by the SBA size standard. 
For 2012, OSHA estimated that all 567 Class II and Class III railroads 
(combined total of 17,800 workers) qualified as small entities 
according to the SBA definitions.
    In a recent study prepared for Congress,\80\ the Federal Railroad 
Administration reported that in 2013, 546 Local/Short Line Railroads 
employed 12,293 workers and earned $2.6 billion in revenue. OSHA 
estimates that of the 16,895 affected employees throughout rail 
transportation, 1,146 employees of Short-Line railroads are affected by 
the final rule.\81\ According to the BLS Quarterly Census of Employment 
and Wages, on average 32 establishments were identified within NAICS 
482112, Short-Line Railroads (an establishment can operate more than 
one railroad). Therefore, if all 546 Class III railroads are controlled 
by 32 establishments, OSHA estimates that revenue per establishment is 
approximately $81.3 million.
---------------------------------------------------------------------------

    \80\ Summary of Class II and Class III Railroad Capital Needs 
and Funding Sources, Federal Railroad Administration, Report to 
Congress, October 2014.http://www.fra.dot.gov/Elib/Document/14131.
    \81\ (16,895 affected workers/181,264 total employees in NAICS 
4821) * 12,293 total Short-Line employees = 1,146 affected Short-
Line employees.
---------------------------------------------------------------------------

    OSHA estimated that compliance costs for rail transportation will 
total $16,562,059. Therefore, if costs per affected worker ($980 per 
worker) are apportioned to the establishments operating Short-Line 
Railroads, OSHA estimates that costs for these local railroads will 
total $1.1 million, or roughly $35,100 per establishment. As noted 
above, annual revenues among Short-Line rail operations total 
approximately $2.6 billion, or $81.3 million per establishment. 
Applying the industry-wide profit rate of 6.23 percent for NAICS 4821, 
OSHA estimated that profits per establishment in NAICS 482112 are $5.1 
million. Therefore, OSHA estimates that impacts measured as costs as a 
percent of revenues will not exceed 0.04 percent, and that impacts 
measured as costs as a percent of profits will not exceed 0.69 percent. 
Thus, OSHA concludes that the silica standard will not impose a 
significant impact on a substantial number of small entities in rail 
transportation and therefore will not threaten the competitive 
structure or viability of small entities in NAICS 482110.
d. Economic Feasibility Screening Analysis: Small and Very Small 
Businesses
    The preceding discussion focused on the economic viability of the 
affected industries in their entirety. Even though OSHA found that the 
final standard did not threaten the survival of these industries, there 
is still the possibility that the competitive structure of these 
industries could be significantly altered.
    To address this possibility, OSHA followed its normal rulemaking 
procedure for examining the annualized costs per affected small entity 
and per very small entity for each affected industry in general 
industry and maritime. Again, OSHA used its typical minimum threshold 
level of annualized costs equal to one percent of annual revenues--and, 
secondarily, annualized costs equal to ten percent of annual profits--
below which the Agency has concluded that the costs are unlikely to 
threaten the survival of small entities or very small entities or, 
consequently, to alter the competitive structure of the affected 
industries.
    Compliance costs for entities with fewer than 20 employees were 
estimated, in many cases, using a derived compliance cost per employee. 
Assuming costs to be equally distributed among all employees, OSHA 
estimated the compliance cost per employee by dividing total costs for 
each NAICS by the number of employees. OSHA then multiplied the 
compliance cost per employee with the ratio of the average number of 
employees per entity with fewer than 20 employees. Similarly, 
compliance costs per small entity were estimated from the product of 
compliance costs per employee and the

[[Page 16552]]

average number of employees in entities within the SBA classification 
for the given NAICS. However, some compliance costs, such as some 
engineering control costs, were modified to reflect diseconomies of 
scale for very small establishments.
    As shown in Table VII-19 and Table VII-20, the annualized cost of 
the final rule is estimated to be $2,967 for the average small entity 
in general industry and maritime and $1,532 for the average very small 
entity in general industry and maritime. These tables also show that 
the only industry in which the annualized costs of the final rule for 
small entities exceed one percent of annual revenues is NAICS 213112 
(Support Activities for Oil and Gas Operations), which is estimated to 
be 1.29 percent. There are two industries for very small entities 
exceeding one percent of annual revenues--NAICS 213112 (Support 
Activities for Oil and Gas Operations), 2.09 percent and NAICS 327110 
(Pottery, Ceramics, and Plumbing Fixture Manufacturing), 1.21 percent.
    Small entities in nine industries in general industry and maritime 
are estimated to have annualized costs in excess of ten percent of 
annual profits; NAICS 327110: Pottery, Ceramics, and Plumbing Fixture 
Manufacturing (38.6 percent); NAICS 327120: Clay Building Material and 
Refractories Manufacturing (33.6 per cent); NAICS 327991: Cut Stone and 
Stone Product Manufacturing (24.7 percent); NAICS 327999: All Other 
Miscellaneous Nonmetallic Mineral Product Manufacturing (20.9 percent); 
NAICS 327390: Other Concrete Product Manufacturing (18.6 percent); 
NAICS 213112: Support Activities for Oil and Gas Operations (18.2 
percent); NAICS 327332: Concrete Pipe Manufacturing (14.5 percent); 
NAICS 327331: Concrete Block and Brick Manufacturing (13.1 percent); 
and NAICS 327320: Ready-Mix Concrete Manufacturing (11.5 percent).
    Very small entities in sixteen industries are estimated to have 
annualized costs in excess of ten percent of annual profit: NAICS 
327110: Pottery, Ceramics, and Plumbing Fixture Manufacturing (90.6 
percent); NAICS 327120 Clay Building Material and Refractories 
Manufacturing (58.5 percent); NAICS 327999: All Other Miscellaneous 
Nonmetallic Mineral Product Manufacturing (51.1 percent); NAICS 327991: 
Cut Stone and Stone Product Manufacturing (30.8 percent); NAICS 213112: 
Support Activities for Oil and Gas Operations (29.5 percent); NAICS 
327390: Other Concrete Product Manufacturing (29.2 percent); NAICS 
327212: Other Pressed and Blown Glass and Glassware Manufacturing (22.7 
percent); NAICS 327332: Concrete Pipe Manufacturing (22.1 percent); 
NAICS 327211: Flat Glass Manufacturing (20.4 percent); NAICS 327331: 
Concrete Block and Brick Manufacturing (19.5 percent); NAICS 327993: 
Mineral Wool Manufacturing (17.4 percent); NAICS 327992: Ground or 
Treated Mineral and Earth Manufacturing (16.3 percent); NAICS 327320: 
Ready-mix Concrete Manufacturing (15.9 percent); NAICS 331513: Steel 
Foundries (except investment) (12.3 percent); NAICS 331524: Aluminum 
Foundries (except die-casting) (11.3 percent); and NAICS 331511: Iron 
Foundries (10.0 percent).
    In general, cost impacts for affected small entities or very small 
entities will tend to be somewhat higher, on average, than the cost 
impacts for the average business in those affected industries. That is 
to be expected. After all, smaller businesses typically suffer from 
diseconomies of scale in many aspects of their business, leading to 
lower revenue per dollar of cost and higher unit costs. Small 
businesses are able to overcome these obstacles by providing 
specialized products and services, offering local service and better 
service, or otherwise creating a market niche for themselves. The 
higher cost impacts for smaller businesses estimated for this rule 
generally fall within the range observed in other OSHA regulations for 
which there is no record of major industry failures.
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BILLING CODE 4510-26-C
    In allocating the share of costs to very small entities, OSHA did 
not have direct information about how many very small entities were 
engaged in silica-related activities. Instead, OSHA assumed that the 
affected employees would be distributed among entities of different 
size according to each entity size class's share of total employment. 
In other words, if 15 percent of employees in an industry worked in 
very small entities (those with fewer than 20 employees), then OSHA 
assumed that 15 percent of affected employees in the industry

[[Page 16572]]

would work in very small entities. However, in reality, OSHA 
anticipates that in industries with foundries, none of the entities 
with fewer than 20 employees have foundries or, if they do, that the 
impacts are much smaller than estimated here.
SBREFA Comments on Impacts on General Industry and Maritime
    In this section, OSHA reviews comments addressing economic impacts 
in general industry and maritime that were submitted during the SBREFA 
process prior to the PEA. OSHA addressed these comments in the PEA that 
was made available for public comment, but OSHA did not receive 
comments specifically addressing its responses to the SBREFA 
recommendations. OSHA is reprinting its responses here for the 
convenience of the reader.
    SERs from foundries stated that there had been a long-run decline 
in the number of foundries in the United States, with the industry 
under continued pressure from foreign competitors and the need to meet 
new domestic regulations. The total expense of the draft standard and 
inability to meet lower PELs would pressure more U.S. foundries out of 
business, continuing an historical trend in this industry, SERs said. 
The variability in the foundry products and small open-area production 
plants would make meeting lower PELs difficult and costly. Many smaller 
foundries would be put out of business, the SERs said, and many jobs 
lost in the industry. ``Twenty percent of profits is a great deal to 
spend on engineering controls with questionable results . . . . [t]he 
economics of the foundry industry today are not pretty,'' one SER said. 
And another: ``The cost of meeting the standard will be very difficult 
. . . . A PEL of 50 would put us out of business.'' OSHA found in this 
FEA that costs as percentage of profits for even very small foundries 
would not rise to a level of 20 percent.
    SERs from the brick industry stated that meeting the provisions of 
the draft proposed standard, particularly with a lower PEL, would be 
very tough for their competitive, low margin industry. Similarly, a SER 
from the pre-cast concrete industry said, ``The problem is not putting 
the company out of business, but that the price of products will 
increase.'' OSHA found that because bricks face limited foreign 
competition, a very small change in the price of bricks would not 
affect the viability of the industry.
    Other SERs (industrial sand, molding powders, refractory concrete) 
noted that the impact of the standard on them, particularly if the PEL 
is lowered, would entail substantial costs, but indirect effects could 
be significant as well since their major customers (foundries) could be 
negatively impacted, too. ``Refractory companies are going out of 
business with the foundries,'' one SER said. OSHA has concluded that 
foundries will not, in general go out of business.
e. Regulatory Flexibility Screening Analysis
    To determine if the Assistant Secretary of Labor for OSHA can 
certify that the final silica standard for general industry and 
maritime will not have a significant economic impact on a substantial 
number of small entities, the Agency has developed screening tests to 
consider minimum threshold effects of the final standard on small 
entities. The minimum threshold effects for this purpose are annualized 
costs equal to one percent of annual revenues and annualized costs 
equal to five percent of annual profits applied to each affected 
industry. (OSHA uses five percent as a threshold for significant 
impacts on small entities rather than the ten percent used for 
potentially serious impacts on industries in order to assure that small 
entity impacts will always receive special attention.) OSHA has applied 
these screening tests both to small entities and to very small 
entities. For purposes of certification, the threshold level cannot be 
exceeded for affected small entities or very small entities in any 
affected industry. Table VII-19 and Table VII-20 show that, in general 
industry and maritime, the annualized costs of the final rule exceed 
one percent of annual revenues for small entities and very small 
entities in one industry. These tables also show that the annualized 
costs of the final rule exceed five percent of annual profits for small 
entities in 15 industries and for very small entities in 25 industries. 
OSHA is therefore unable to certify that the final rule will not have a 
significant economic impact on a substantial number of small entities 
in general industry and maritime and must prepare a Final Regulatory 
Flexibility Analysis (FRFA). The FRFA is presented in Section VII.I of 
this preamble.
3. Impacts in Construction
a. Economic Feasibility Screening Analysis: All Establishments
    To determine whether the final rule's estimated costs of compliance 
would threaten the economic viability of affected construction 
industries, OSHA used the same data sources and methodological approach 
that were used earlier in this section for general industry and 
maritime. OSHA first compared, for each affected construction industry, 
annualized compliance costs to annual revenues and profits per 
(average) affected establishment. The results for all affected 
establishments in all affected construction industries are presented in 
Table VII-21, using annualized costs per establishment for the final 
PEL of 50 [mu]g/m\3\.
    The annualized cost of the rule for the average establishment in 
construction, encompassing all construction industries, is estimated at 
$1,097 in 2012 dollars. The estimates of the annualized costs per 
affected establishment range from $4,811 for NAICS 237300 (Highway, 
Street, and Bridge Construction) and $4,463 for NAICS 237100 (Utility 
System Construction) to $364 for NAICS 236100 (Residential Building 
Construction) and $360 for NAICS 221100 (Electric Utilities).
    Table VII-21 shows that the annualized costs of the rule do not 
exceed one percent of annual revenues or 10 percent of annual profits 
for any affected construction industry. NAICS 238100 (Foundation, 
Structure, and Building Exterior Contractors) has both the highest cost 
impact as a percentage of revenues, of 0.12 percent, and the highest 
cost impact as a percentage of profits, of 3.66 percent. For all 
affected establishments in construction, the estimated annualized cost 
of the final rule is, on average, equal to 0.05 percent of annual 
revenue and 1.52 percent of annual profit. These are well below the 
minimum threshold levels of 1 percent and 10 percent, respectively.
    Therefore, even though the annualized costs of the final rule 
incurred by the construction industry as a whole are roughly twice the 
combined annualized costs incurred by general industry and maritime, 
OSHA concludes, based on its screening analysis, that the annualized 
costs as a percentage of annual revenues and as a percentage of annual 
profits are below the threshold level that could threaten the economic 
viability of any of the construction industries. OSHA therefore finds 
that the final rule is economically feasible for each of the industries 
engaged in construction activities. OSHA further notes that while there 
would be additional costs (not attributable to the final rule) for some 
employers in construction industries to come into compliance with the 
preceding silica standard, these costs would not affect the Agency's

[[Page 16573]]

determination of the economic feasibility of the final rule.
    Below, OSHA provides additional information to further support the 
Agency's conclusion that the final rule would not threaten the economic 
viability of any construction industry.
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b. Normal Year-to-Year Variations in Profit Rates
    As previously noted, the United States has a dynamic and constantly 
changing economy in which large year-to-year changes in industry profit 
rates are commonplace. A recession, a downturn in a particular 
industry, foreign competition, or the increased competitiveness of 
producers of close domestic substitutes are all easily capable of 
causing a decline in profit rates in an industry of well in excess of 
10 percent in one year or for several years in succession.
    To demonstrate the normal year-to-year variation in profit rates 
for all the establishments in construction affected by the final rule, 
OSHA presented data in the FEA on year-to-year profit rates and year-
to-year percentage changes in profit rates, by industry, for the years 
2000-2012. For the combined affected industries in construction over 
the 13-year period, the average change in profit rates was 63.09 
percent a year. If the three worst years are excluded, there is still 
substantial variation in profits, far larger than the change in profits 
that would be necessary if the costs of this rule cannot be passed on.
    These data indicate that even if the annualized costs of the final 
rule for the most significantly affected construction industries were 
completely absorbed in reduced annual profits, the magnitude of reduced 
annual profit rates is well within normal year-to-year variations in 
profit rates in those industries and does not threaten their economic 
viability. Of course, a permanent loss of profits would present a 
greater problem than a temporary loss, but it is unlikely that all 
costs of the final rule would be absorbed in lost profits. Given that, 
as discussed in Chapter VI of the FEA, the overall price elasticity of 
demand for the outputs of the construction industry is fairly low and 
that almost all of the costs estimated in Chapter V of the FEA are 
variable costs, the data and economic theory suggest that most firms 
will see small declines in output rather than that any but the most 
extremely marginal firms would face any real risk of closure. Many 
parts of the construction industry have already absorbed much more 
drastic changes in profit without evidence of industry collapse or 
major change.
Market Structure and Market Impacts in the Construction Industry
    At a conceptual level, the market-determined output of the 
construction industry depends on the intersection of demand and supply 
curves. Incremental compliance costs of the rule (which are almost 
entirely variable costs) shift the construction supply curve upward. 
The net effect is an increase in the price for construction activities 
and a reduction in the level of activity (with the magnitude of this 
effect depending on the price elasticity of demand). Lower levels of 
activity mean less construction work, a reduction in the number of 
construction establishments, and a concomitant reduction in 
construction employment. The greater the price elasticity of demand and 
the greater the increase in marginal costs, the larger will be the 
reduction in equilibrium output. In terms of prices, the greater the 
price elasticity of demand, the smaller the increase in prices will be 
for a given increment to marginal costs, and the larger the reduction 
in output.
    Increasing the cost of construction project activities that 
generate silica exposures has two effects on the demand for these 
activities. First, increasing the cost of silica-related jobs relative 
to the costs of other construction inputs might result in substitution 
away from this type of work. Architects, building designers, and 
contractors might be more likely to choose building methods and 
materials that eliminate or reduce the need to perform silica-related 
jobs. For example, pre-cast concrete structures that require a 
relatively high level of concrete finishing work would become more 
expensive relative to other building technologies. Contractors and 
others could reduce the cost impact of the standard by switching to 
other building methods unaffected by the silica rule when the 
alternative would result in lower cost than would compliance with the 
rule. The magnitude of these impacts will depend on the feasibility, 
characteristics, and relative expense of alternative technologies.
    Second, some of the increase in the cost of silica-generating 
activities will increase the marginal cost of construction output and 
cause the construction supply curve to shift upward, resulting in a 
higher price for each quantity produced. The magnitude of the impact of 
the cost increases due to the silica rule on the supply relationship 
will depend on the size of the cost increases and the importance of 
silica-generating activities in the overall cost of construction 
projects. If the silica-generating activities are a small portion of 
the overall cost of construction then the supply curve shift will be 
smaller when compared to a shift in the supply curve from silica-
generating activity that is a large portion of the overall cost of 
construction. If, for example, there is a one percent increase in the 
costs of a silica generating activity and the silica generating 
activity constitutes only one percent of the costs of a building, then 
the total increase in the cost of the building will be an almost 
unobservable 0.01 percent. Magnitude of shifts in derived demand for a 
service used in making another product are determined by the price 
change for the final product, not the price change for the service 
itself.
    In practice, if one considers the costs of the final rule relative 
to the size of construction activity in the United States, it is clear 
that the price and profit impacts of the final rule on construction 
industries must be quite limited. The annualized cost of the final rule 
would be equal to approximately 0.1 percent of the value of annual 
construction activity in the U.S. Moreover, construction activity in 
the U.S. is not subject to any disadvantage from foreign competition--
any foreign firms performing construction activities in the United 
States would be subject to OSHA regulations.
c. Impacts by Type of Construction Demand
    The demand for construction services originates in three 
independent sub-sectors: residential building construction, 
nonresidential building construction, and nonbuilding construction.
    Residential Building Construction: Residential building demand is 
derived from the household demand for housing services. These services 
are provided by the stock of single and multi-unit residential housing 
units. Residential housing construction represents changes to the 
housing stock and includes construction of new units and modifications, 
renovations, and repairs to existing units. A number of studies have 
examined the price sensitivity of the demand for housing services. 
Depending on the data source and estimation methodologies, these 
studies have estimated the demand for housing services at price 
elasticity values ranging from -0.40 to -1.0, with the smaller (in 
absolute value) less elastic values estimated for short-run periods 
(Glennon, 1989, Document ID 0707; Mayo, 1981, Document ID 0794). In the 
long run, it is reasonable to expect the demand for the stock of 
housing to reflect similar levels of price sensitivity.
    Many of the silica-generating construction activities affected by 
the rule are not widely used in single-family construction or 
renovation. This assessment is consistent with the cost estimates that 
show relatively low impacts for residential building contractors. (See 
Table VI-9 of the FEA--the costs as a percent of revenues

[[Page 16575]]

for Residential Building Construction are estimated to be 0.03 percent 
and the costs as a percent of profits are estimated to be 1.29 
percent). Multi-family residential construction might have more 
substantial impacts, but, based on Census data, this type of 
construction represents a relatively small share of net investment in 
residential buildings.
    Nonresidential Building Construction: Nonresidential building 
construction consists of industrial, commercial, and other 
nonresidential structures. As such, construction demand is derived from 
the demand for the output of the industries that use the buildings. For 
example, the demand for commercial office space is derived from the 
demand for the output produced by the users of the office space. The 
price elasticity of demand for this construction category will depend, 
among other things, on the price elasticity of demand for the final 
products produced, the importance of the costs of construction in the 
total cost of the final product, and the elasticity of substitution of 
other inputs that could substitute for nonresidential building 
construction. ERG (2007c) found no studies that attempted to quantify 
these relationships (Document ID 1710). But given the costs of the 
final rule relative to the size of construction spending in the United 
States, the resultant price or revenue effects are likely to be quite 
small as well.
    Nonbuilding Construction: Nonbuilding construction includes roads, 
bridges, and other infrastructure projects. Utility construction (power 
lines, sewers, water mains, etc.) and a variety of other construction 
types are also included. A large share of this construction (63.8 
percent) is publicly financed (ERG, 2007a, Document ID 1709). For this 
reason, a large percentage of the decisions regarding the appropriate 
level of such investments is not made in a private market setting. The 
relationship between the costs and price of such investments and the 
level of demand might depend more on political considerations than the 
factors that determine the demand for privately produced goods and 
services.
    While a number of studies have examined the factors that determine 
the demand for publicly financed construction projects, these studies 
have focused on the ability to finance such projects (e.g., tax 
receipts) and socio-demographic factors (e.g., population growth) to 
the exclusion of cost or price factors. In the absence of budgetary 
constraints, the price elasticity of demand for public investment is 
therefore probably quite low. On the other hand, budget-imposed limits 
might constrain public construction spending. If the dollar value of 
public investments were fixed, a price elasticity of demand of 1 would 
be implied and any percentage increase in construction costs would be 
offset with an equal percentage reduction in investment (measured in 
physical units), keeping public construction expenditures constant.
    Public utility construction comprises the remainder of nonbuilding 
construction. This type of construction is subject to the same derived-
demand considerations discussed for nonresidential building 
construction, and for the same reasons, OSHA expects the price and 
profit impacts to be quite small.
SBREFA Comments on Impacts on the Construction Industry
    In this section OSHA reviews comments addressing economic impacts 
in construction that were submitted during the SBREFA process prior to 
the PEA. OSHA addressed these comments in the PEA that was made 
available for public comment, but did not receive comments specifically 
addressing its responses to the SBREFA recommendations. OSHA is 
reprinting its responses here for the convenience of the reader.
    One commenter believed that OSHA had ignored the range of 
profitability among businesses, and thus did not adequately recognize 
that the average percentage reduction in profits could mean bankruptcy 
for those firms struggling to stay afloat. The Agency's approach to 
economic feasibility is designed to address the overall health of 
industries in compliance with legal precedent, which permits OSHA to 
find a regulation economically feasible even though it may close some 
marginal firm. In most years, ten percent or more of construction firms 
exit the industry (See U.S. Census Bureau Business Dynamics Statistics, 
available at http://www.census.gov/ces/dataproducts/bds/data_firm.html). The slight acceleration of the closure of such firms 
is not the kind of economic impact that would make a regulation 
economically infeasible.
    The commenter also asserted that OSHA ignored the cost of credit 
and that this also varies across businesses. OSHA believes that the 
cost of credit is not an important issue in this case because OSHA's 
analysis demonstrates that, in most cases, upfront costs can usually be 
met from cash flow. Earlier in this chapter, OSHA noted that its choice 
of a threshold level of ten percent of annual profits for economic 
feasibility determinations is low enough that even if, in a 
hypothetical worst case, all compliance costs were upfront costs, then 
upfront costs would still equal 88.5 percent of profits and thus would 
be affordable from profits alone without needing to resort to credit 
markets. As shown in Table VI-12 of the FEA, all industries' costs are 
a very small percentage of profits, assuring that even upfront costs 
can be met from profits without resorting to credit markets. Further, a 
firm that is having trouble meeting upfront costs can rent the 
appropriate tools without incurring any upfront capital investment 
costs.
    A SER asserted that the impact of the rule would be 
``catastrophic'' for the concrete cutting industry. One SER maintained 
that the rule would be both economically and technologically infeasible 
for the specialty trade concrete cutting industry (Document ID 0937, p. 
69). The Small Business Advocacy Review (SBAR) Panel recommended that 
OSHA thoroughly review the economic impacts, and develop a more 
detailed economic feasibility analysis for certain industries (Document 
ID 0937, p. 69). OSHA believes that the analyses in this chapter and in 
Chapter IX of the FEA address the SER's comments and the SBAR Panel 
recommendations.
    Concrete cutting is undertaken for such purposes as grooving for 
projects such as highways, bridges, and sidewalks along with repairing 
these structures when they become operationally unsound. These 
contracts are bid on by firms who will all fall under the final silica 
rule, so there is no economic disadvantage between firms caused by the 
silica rule. Because the silica rule only applies in areas subject to 
OSHA jurisdiction, there is no foreign competition that would not also 
be subject to the silica standard. The cutting industry also works on 
runways and parking lots along with homebuilders for smaller projects. 
The demand for these products are relatively inelastic and not subject 
to foreign competition, enabling these companies to pass most of the 
costs of this final rule onto their consumers. Based on these analyses, 
OSHA disagrees that the rule would be ``catastrophic'' or economically 
infeasible for the concrete cutting industry.
d. Economic Feasibility Screening Analysis: Small and Very Small 
Businesses
    The preceding discussion focused on the economic viability of the 
affected construction industries in their entirety. However, even 
though OSHA found that the silica standard did not threaten the

[[Page 16576]]

survival of these construction industries, there is still the 
possibility that the industries' competitive structures could be 
significantly altered.
    To address this possibility, OSHA examined the annualized costs per 
affected small and very small entity for each affected construction 
industry. Table VII-22 and Table VII-23 show that in no construction 
industries do the annualized costs of the final rule exceed one percent 
of annual revenues or 10 percent of annual profits either for small 
entities or for very small entities. Therefore, OSHA concludes, based 
on its screening analysis, that the annualized costs as a percentage of 
annual revenues and as a percentage of annual profits are below the 
threshold level that could threaten the competitive structure of any of 
the construction industries.
BILLING CODE 4510-26-P

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[GRAPHIC] [TIFF OMITTED] TR25MR16.093


[[Page 16578]]


[GRAPHIC] [TIFF OMITTED] TR25MR16.094

BILLING CODE 4510-26-C

[[Page 16579]]

e. Differential Impacts on Small Entities and Very Small Entities
    Below, OSHA provides some additional information about differential 
compliance costs for small and very small entities that might influence 
the magnitude of differential impacts for these smaller businesses.
    The distribution of impacts by size of business is affected by the 
characteristics of the compliance measures. For silica controls in 
construction, the dust control measures consist primarily of equipment 
modifications and additions made to individual tools, rather than 
large, discrete investments, such as might be applied in a 
manufacturing setting. As a result, compliance advantages for large 
firms through economies of scale are limited. It is possible that some 
large construction firms might derive purchasing power by buying dust 
control measures in bulk. However, given the simplicity of many control 
measures, such as the use of wet methods on machines already 
manufactured to accommodate controls, such differential purchasing 
power appears to be of limited consequence.
    The greater capital resources of large firms will give them some 
advantage in making the relatively large investments needed for some 
control measures. For example, cab enclosures on heavy construction 
equipment or foam-based dust control systems on rock crushers might be 
particularly expensive for some small entities with an unusual number 
of heavy equipment pieces. Nevertheless, where differential investment 
capabilities exist, small construction firms may also have the 
capability to achieve compliance with lower-cost measures, such as by 
modifying work practices. In the case of rock crushing, for example, 
simple water spray systems can be arranged without large-scale 
investments in the best commercially available systems.
    In the program area, large firms might have a slight advantage in 
the delivery of training or in arranging for health screenings. This 
phenomenon has been accounted for in the analysis that OSHA provides.
f. Regulatory Flexibility Screening Analysis
    To determine if the Assistant Secretary of Labor for OSHA can 
certify that the final silica standard for construction will not have a 
significant economic impact on a substantial number of small entities, 
OSHA applies the same screening analysis to construction as it does for 
general industry, as discussed earlier in that section for the same 
reasons: annualized costs equal to one percent of annual revenues and 
annualized costs equal to five percent of annual profits applied to 
each affected industry. OSHA has applied these screening tests both to 
small entities and to very small entities. For purposes of 
certification, the threshold levels cannot be exceeded for affected 
small or very small entities in any affected industry.
    Table VII-22 and Table VII-23 show that in no construction 
industries do the annualized costs of the final rule exceed one percent 
of annual revenues or five percent of annual profits either for small 
entities or for very small entities. However, as previously noted in 
this section, OSHA is unable to certify that the final rule will not 
have a significant economic impact on a substantial number of small 
entities in general industry and maritime and must prepare a Final 
Regulatory Flexibility Analysis (FRFA). The FRFA is presented in 
Section VII.I of this preamble.
4. Employment Impacts on the U.S. Economy
    The discussion below on employment impacts of the silica rule on 
the U.S. economy is divided into three parts: (1) a brief summary of 
the employment impacts of the proposed silica rule (based on an 
analysis performed for OSHA by its subcontractor, Inforum, in 2011, 
Document ID 1701) that the Agency included in the PEA in support of the 
silica proposal; (2) a review of estimates provided by commenters on 
the employment effects of the silica proposal; and (3) a summary of a 
recent analysis of the employment effects of the final silica rule that 
Inforum performed for OSHA, followed by a critique of the commenters' 
analysis of employment effects relative to Inforum's analysis.
a. Inforum Analysis of Employment Effects Prepared for Silica Proposal
    In October 2011, OSHA directed Inforum \82\ to run its 
macroeconomic model to estimate the employment impacts of the costs 
\83\ of the proposed silica rule. Inforum ran the model for the ten-
year period 2014-2023 and reported its annual and cumulative employment 
and other macroeconomic results. While employment effects varied from 
year to year and from industry to industry, a key Inforum result was 
that the proposed silica rule cumulatively would generate an additional 
8,625 job-years over the period 2014--2023, or an additional 862.5 job-
years annually, on average, over the period.\84\ A fuller discussion of 
Inforum's macroeconomic model and the results of its analysis can be 
found in Chapter VI of the PEA in support of OSHA's silica proposal and 
in the Inforum report itself (Inforum, 2011, Document ID 1701).
---------------------------------------------------------------------------

    \82\ Inforum, which stands for the INterindustry FORecasting at 
the University of Maryland, is a not-for-profit Maryland 
corporation. Inforum has over 45 years of experience designing and 
using macroeconomic models of the United States (and other 
countries). Details of Inforum's macroeconomic model are presented 
later in this section.
    \83\ The estimated cost at the time was approximately $650 
million in 2009 dollars using a 3 percent discount rate.
    \84\ A ``job-year'' is the term of art used to reflect the fact 
that an additional person is employed for a year, not that a new job 
has necessarily been permanently created.
---------------------------------------------------------------------------

b. Estimates by Commenters on Employment Effects of the Silica Proposal
    Three commenters on the silica proposal--the National Federation of 
Independent Business (NFIB) with the NFIB Research Foundation; the 
American Chemistry Council (ACC) with Stuart Sessions of Environomics, 
Inc.; and the Construction Industry Safety Coalition (CISC) with 
Environomics, Inc.--provided or reported estimates of the employment 
effects of the proposed silica rule. These commenter estimates are 
summarized below.
    The NFIB Research Foundation performed a study (Document ID 2210, 
Attachment 2) to estimate the employment and other macroeconomic 
effects of OSHA's proposed rule, using the Agency's own estimates of 
the annualized compliance costs of the proposed rule for affected 
employers of approximately $637 million in 2009 dollars. The study 
modeled (a) anticipated employer costs due to the proposed rule, (b) 
changes to private sector demand, and (c) changes to state and local 
government spending associated with the proposed rule, and then 
forecast their effects using NFIB's Business Size Impact Module (BSIM) 
to run a simulation. The BSIM is a dynamic, multi-region model based on 
the Regional Economic Models, Inc. (REMI) structural economic 
forecasting and policy analysis model, which integrates input-output, 
computable general equilibrium, econometric, and economic geography 
methodologies. Costs were estimated by five size classes of firms. It 
was noted that the annualized compliance costs of the proposed rule:

    . . . also represent new demand for private sector goods and 
services for firms who assist businesses affected by the new PEL in

[[Page 16580]]

complying with the proposed rule. In the BSIM, this new demand for 
goods and services provided by the private sector acts as a 
countervailing force to any negative impact on employers the new 
annualized compliance costs may have (Document ID 2210, Attachment 
2, p. 8).

    The summary findings of the NFIB Research Foundation study included 
an overall loss of 27,000 jobs and lost output of over $72 billion in 
the long run, with at least half the loss expected to occur in the 
small business sector.
    The American Chemistry Council (ACC) (Document ID 4209-A1) reported 
on Mr. Sessions's post-hearing brief (Document ID 4231), which provided 
estimates of the economic and employment impacts of the general 
industry costs to comply with the proposed silica rule and, in 
addition, criticized Inforum's estimates of the employment effects of 
the proposed silica rule (Inforum, 2011, Document ID 1701).
    Mr. Sessions estimated economic impacts based on the URS 
Corporation estimates of $6.131 billion as the cost of the proposed 
silica rule on 19 general industry sectors (Document ID 4209-1, pp. 
102-103). (Note that the analysis does not include the construction 
sector and is more than 50 times higher than OSHA's general industry 
cost estimate in the proposal). The economic impacts were estimated in 
two analytical steps: (1) estimate the impact of the proposed 
regulation's compliance costs on the value of output of the affected 
industries; and (2) estimate how the expected changes in output will 
reverberate throughout the economy, using IMPLAN--a well-known input-
output model of the U.S. economy.
    The first step was achieved by estimating the amount of cost pass-
through of the compliance costs, using a supply elasticity of 1.0, and 
then estimating the demand response to this price increase assuming a 
demand elasticity of -1.5. This results in a decline in industry 
revenue equal to about 20 percent of annualized compliance costs, 
which--given URS's estimates of compliance costs--is equal to $1.23 
billion per year. Again using the IMPLAN model, the corresponding 
estimated employment effect is 18,000 lost jobs annually (5,400 direct 
effect; 5,000 indirect effect; and 7,500 induced effect) and a loss in 
economic output/GDP of more than $1.6 billion per year.
    Additionally, Mr. Sessions reviewed Inforum's analysis of the 
employment impacts of the proposed rule. He asserted that OSHA had 
supplied Inforum with year-by-year compliance costs that were only 53 
percent of the annualized costs that OSHA had estimated in the PEA so 
that Inforum's projections of employment effects would be seriously 
underestimated:

    OSHA estimates the cost of the Proposed Standard to be $658 
million per year in 2009 dollars on an annualized basis, excluding 
the hydraulic fracturing industry. Assuming a 7%/year discount rate, 
this annual cost, continuing forever as OSHA estimates it will, is 
equivalent to a present value cost of $9.4 billion dollars in the 
initial year of compliance. For comparison with this figure, I 
calculate (also assuming a 7% discount rate) that the present value 
in the first year for the ten-year schedule of compliance costs 
shown in Inforum's Table 1 is only $5.0 billion [italics added] 
(Document ID 4231).

    In reviewing the above procedures, OSHA concludes that Mr. Sessions 
has misinterpreted his own calculations. The annualized value of an 
infinite series of costs (i.e., continuing forever) discounted at 7 
percent is equal to 0.07 (the annualization factor) x the present value 
(PV). Hence, the annualized cost of Mr. Session's present value of $9.4 
billion should equal $658 million. Now, OSHA provided a stream of costs 
for 10 years, not forever. The annualization factor for annualized 
costs incurred over ten years using a 7 percent discount rate is equal 
to 0.1424. Therefore, the PV of OSHA's costs given to Inforum should be 
$658 million/0.1424, or about $4.6 billion. Mr. Sessions only confused 
issues by using first-year costs (which is irrelevant to his exercise) 
rather than annualized costs. So, there is nothing in Mr. Sessions's 
calculations that would suggest that OSHA had provided Inforum with 
seriously incomplete costs. However, just to make sure, OSHA and ERG 
also reviewed the year-by-year proposal cost data given to Inforum (for 
Inforum, 2011, Document ID 1701) and found nothing amiss.
    The Construction Industry Safety Coalition, submitted a late 
comment on the silica proposal (CISC, 2015), which contains estimates 
prepared by Environomics, Inc. (Environomics, 2015) of the employment 
impacts of the proposed silica rule on the construction sector 
(Document ID 4242). This late comment, including the contained 
Environomics study, has been excluded from OSHA decision-making 
consideration, but is presented here for informational purposes only.
    The employment effects estimated by Environomics (2015) reflect 
annual costs to construction industries of $4.9 billion, which includes 
almost $3.9 billion of direct compliance costs to construction 
employers and another $1.05 billion of costs passed through from 
general industry (as a result of the silica rule for general industry) 
to the construction industry (Document ID 4242). Environomics used the 
IMPLAN model to translate the estimated $4.9 billion annual cost of the 
silica rule into more than 52,700 lost jobs related to the construction 
industry. These job losses would consist of about 20,800 in 
construction; 12,180 additional jobs lost in industries that supply 
materials, products, and services to the construction industry; and 
nearly 20,000 further jobs lost when those who lose their jobs in 
construction and supplier industries no longer have earnings to spend 
(i.e., ``induced'' jobs). Furthermore, Environomics argued that 
``(t)hese job figures are expressed on a full-time equivalent basis. 
Given the number of part-time and seasonal jobs in construction, the 
number of actual workers and actual jobs affected will be much more 
than 52,700'' (Environomics, 2015, Document ID 4242, p. 2).
c. Inforum Analysis of Employment Effects of the Final Silica Rule
    In December 2015, OSHA directed Inforum to run its macroeconomic 
model to estimate the industry and aggregate employment impacts on the 
U.S. economy of the cost of OSHA's final silica rule.\85\ The Agency 
believes that the specific model of the U.S. economy that Inforum 
uses--called the LIFT (Long-term Interindustry Forecasting Tool) 
model--is particularly suitable for this work because it combines the 
industry detail of a pure input-output model (which shows, in matrix 
form, how the output of each industry serves as inputs in other 
industries) with macroeconomic modeling of demand, investment, and 
other macroeconomic parameters.\86\ The Inforum model can thus both 
trace changes in particular industries through their effect on other 
industries and also

[[Page 16581]]

examine the effects of these changes on aggregate demand, imports, 
exports, and investment, and in turn determine net changes to Gross 
Domestic Product (GDP), employment, prices, etc.
---------------------------------------------------------------------------

    \85\ The estimated cost of the final rule that OSHA provided 
Inforum was about $962 in annualized terms in December 2015. The 
final cost presented in the FEA is about $1,030 million in 
annualized terms, or about 7 percent ($68 million) higher than the 
costs used by Inforum to estimate the employment effects of the 
final rule. OSHA believes that if the most recent cost estimates had 
been used, they would have had a minor effect on Inforum's estimate 
of the employment impact of the final rule.
    \86\ The LIFT model combines a dynamic input-output (I-O) core 
for 110 productive sectors with a full macroeconomic model with more 
than 1,200 macroeconomic variables that are consistent with the 
National Income and Product Accounts (NIPA) and other published 
data. LIFT employs a ``bottom-up'' regression approach to 
macroeconomic modeling (so that aggregate investment, employment, 
and exports, for example, are the sum of investment and employment 
by industry and exports by commodity). Unlike some simpler 
forecasting models, price effects are embedded in the model and the 
results are time-dependent (that is, they are not static or steady-
state, but present year-by-year estimates of impacts consistent with 
economic conditions at the time).
---------------------------------------------------------------------------

    Using industry-by-industry compliance cost estimates provided by 
OSHA,\87\ Inforum employed the LIFT model of the U.S. economy to 
compute the industry-level and macroeconomic impacts expected to follow 
implementation of the silica standard. The general methodology was to 
embed the compliance costs into the industry price functions of the 
LIFT model, solve the equations of the model with the additional costs 
included in the calculations, and then compare the simulation to a 
baseline scenario which did not include the additional costs. 
Enforcement of the rule was assumed to start in 2017 in construction 
and in 2018 in general industry and maritime (with enforcement of 
engineering control requirements for hydraulic fracturing activities 
beginning in 2021). The timing of the compliance costs reflected the 
phased-in enforcement of the rule, and the LIFT model results were 
calculated over a ten-year horizon, that is, through 2026.
---------------------------------------------------------------------------

    \87\ OSHA contractor ERG provided silica-rule compliance cost 
data for 13 segments of the construction sector plus construction 
activity by state and local governments, and for 102 industrial 
sectors. The costs were specified in 2012 dollars and covered a 10 
year horizon, beginning with the implementation of the rule. The 
data covered eight cost types and were classified as intermediate, 
capital, and direct labor costs. In order to integrate the 
compliance costs within the LIFT model framework, Inforum 
established a mapping between the OSHA NAICS-based industries and 
the LIFT production sectors. See Inforum (2016) for a discussion of 
these and other transformations of OSHA's cost estimates to conform 
to the specifications of the LIFT model.
---------------------------------------------------------------------------

    The most significant Inforum result is that the final silica rule 
cumulatively generates an additional 9,500 job-years over the period 
2017-2026, or an additional 950 job-years annually, on average, over 
the period (Inforum, 2016). It should be noted, however, that these 
results vary significantly from year to year. For example, in 2017, the 
first year in which the silica final rule would be in effect and when 
most capital costs for control equipment would be incurred, an 
additional 21,100 job-years would be generated as a result of the 
silica rule. Then, through 2026, the change in job-years relative to 
the baseline ranges from a high of 19,600 (in 2019) to a low of -17,300 
(in 2020).\88\ Inforum emphasized that all of these estimated job-year 
impacts of the silica rule, both positive and negative, should be 
viewed as negligible--relative to total U.S. employment of between 157 
and 168 million workers during the time period under consideration and 
not statistically different from an estimate of 0 job-years (that is, 
that the silica rule would have no job impact).
---------------------------------------------------------------------------

    \88\ The fluctuations in employment from year to year as a 
result of the proposed rule reflect how the Inforum model works. The 
model has large short-term multipliers (from the initial increase in 
compliance expenditures) but long-term stabilizers to return to an 
equilibrium output and employment level. Hence, the short-term 
multipliers may cause output and employment to overshoot in one year 
and adjust in the other direction in the next year or two as the 
model (and the real-world economy) equilibrates.
---------------------------------------------------------------------------

    The employment impacts of the silica rule would also vary 
significantly from industry to industry and from sector to sector. For 
example, for the period 2017-2026, the construction industry would, on 
average, gain 4,260 job-years annually while the rest of the U.S. 
economy would, on average, lose 3,310 job-years annually. Again, 
relative to total employment in the construction sector of about 10 
million workers and employment in the rest of the U.S. economy of about 
150 million workers over the 10-year period, these employment impacts 
should be considered negligible. For a fuller discussion of OSHA's 
estimate of the employment and other macroeconomic impacts of the 
silica rule, see Inforum (2016).
    One obvious question is why the employment impacts of the silica 
rule would be positive in construction and negative elsewhere. There 
seem to be two major reasons. One is that, as reflected in the Inforum 
model, there is little foreign competition in U.S. construction and the 
price elasticity of demand in construction is extremely low relative to 
demand for products in most other industries. Hence, output and 
employment would be expected to decline minimally in response to any 
price increase if employers in construction pass on the costs of the 
silica rule. Second, and probably more important, in OSHA's view, 
compliance with many of the provisions in the silica rule is relatively 
labor-intensive, often requiring the application of additional labor in 
the regulated firms themselves. Examples would include time spent for 
training, medical surveillance, and activities to meet the PEL (such as 
setting up and using control equipment and performing housekeeping 
tasks). The increased labor required to produce a unit of output in 
regulated firms would tend to increase employment in those industries 
(holding output constant). This is particularly true in construction, 
where compliance with the PEL would be much more labor-intensive--both 
because engineering controls in construction are typically mobile and 
require more worker activity and because housekeeping and other worker 
actions are expected to play a larger role in achieving compliance with 
the PEL. By comparison, engineering control equipment in general 
industry/maritime is usually in a fixed location (eliminating the need 
for workers to move the equipment) and worker actions would play a 
smaller role in achieving compliance with the PEL.
    Finally, OSHA turns to a critique of the commenters' analysis of 
employment effects of the proposed silica rule relative to Inforum's 
analysis of employment effects of the final silica rule. This critique 
reflects comments provided in the Inforum report (Inforum, 2016).
    The NFIB Research Foundation Analysis: Although the NFIB Research 
Foundation study (Document ID 2210, Attachment 2) reported that careful 
attention was given to the analysis of costs and their attribution by 
firm size, it doesn't offer much information on how the BSIM model 
works or how the results were obtained. ``From what is generally known 
about the REMI model upon which it is based, the general mechanism is 
probably the sequence of (1) increased costs leading to (2) increased 
output price leading to (3) reduced demand and therefore jobs'' 
(Inforum, 2016, p. 8). The study does acknowledge that the costs also 
represent new private sector demand for firms that assist affected 
employers in complying with the new PEL, but the purported positive 
impacts of this private sector demand are not visible in the study. 
Presumably the reported impacts are net effects that combine the 
negative effects from the increased prices and reduced demand of the 
affected sectors with the stimulus from spending on the supplying 
sectors; however, that is not clear, and the stimulus is not 
quantified. In Inforum's analysis (Inforum, 2016), these effects are 
explicitly considered, both for intermediate goods and services as well 
as investment.
    Another important difference from Inforum's analysis is that the 
NFIB study did not attempt to quantify the additional jobs created in 
the affected industries. In Inforum's LIFT model, these were captured 
as changes in labor productivity. For several industries, especially 
construction, although the industry does experience increased costs, it 
must also hire more workers to comply with the silica rule. The 
additional jobs required in the affected industries are not discussed 
or apparently modeled in the NFIB study. In summary, it seems that the

[[Page 16582]]

counteracting influences due to intermediate and investment related 
purchases from other industries, and the job-creating expenditures in 
the affected industries were not, in fact, captured in the study.
    The CISC and ACC Studies: These two studies are being critiqued 
together because they both rely on costs many times higher than OSHA's 
estimates and because they both made projections using the IMPLAN 
model.
    What accounts for the difference between LIFT simulations and the 
CISC and ACC estimates? There are several factors at play:
    Probably most importantly, CISC's estimate starts with annual 
compliance costs for the construction industry that are nearly 7 times 
larger than OSHA's estimates for the construction industry (only) ($4.1 
billion vs. an average of over $600 million, both in 2012 dollars). 
Meanwhile, the ACC study estimates costs for general industry that are 
more than 16 times larger than OSHA's estimates for the final rule 
($6.1 billion in 2009 dollars versus $359 million in 2012 dollars. 
Moreover, the CISC and ACC studies assumes that the same annualized 
cost estimates are imposed each year, whereas the OSHA cost estimates 
vary over the 10 year time period, with peak costs occurring in the 
first year.
    Neither the CISC nor the ACC application of the IMPLAN model 
accounted for the increase in demand for capital equipment and 
intermediate goods and services needed to comply with the proposed 
silica rule. Thus, the employment and income boosting impacts of these 
expenditures are not captured in their analysis. In contrast, Inforum's 
methodology uses an explicit price function where annual compliance 
costs by industry change commodity prices in proportion to their share 
of total annual gross costs. In turn, price changes affect production 
and employment through a dynamic general equilibrium framework. Demand 
and supply price elasticities in the LIFT model are composites of 
several sets of empirically estimated functions for final demand, 
exports, imports, and price mark-ups. Furthermore, the parameters of 
these functions vary by type of product according to the econometric 
estimation.
    At OSHA's request, Inforum made a separate run using the LIFT model 
in the absence of the final silica rule for the construction industry 
but with the final silica rule for general industry and maritime. The 
purpose of this run was to calculate the indirect effects (only) of the 
final silica rule for general industry and maritime on prices and 
employment in the construction industry (Inforum, 2016). This LIFT 
simulation estimated that the final silica rule for general industry 
and maritime indirectly increased prices in the construction industry 
by an average of .005 percent. The direction, if not the magnitude of 
this effect, is consistent with the CISC/Environomics results 
(Environomics, 2015, Document ID 4242). This led to a modest decline in 
construction output and construction jobs. As shown in Table 9 of the 
Inforum report (Inforum, 2016), the decline in jobs varied from +290 to 
-940 a year over the period 2017 to 2026, with a cumulative job impact 
of -4.8 thousand jobs over the 10-year period. Again, it should be 
emphasized that this separate run was made in the absence of the final 
silica rule for the construction industry.\89\
---------------------------------------------------------------------------

    \89\ As shown in Table 6 of the Inforum report, the cumulative 
effect of the final rule for general industry, maritime, and 
construction is to increase construction employment by 42,600 job 
years over the 10-year time period, or about 4,260 jobs a year, on 
average. Hence, the cumulative effect of the final rule for 
construction alone is to increase construction employment by about 
47,400 (42,600 + 4,800) jobs, or about 4,740 jobs a year, to the 
extent that the two components are additive.
---------------------------------------------------------------------------

    The IMPLAN model is static and cannot compute employment and output 
impacts over time, and it cannot show how the economy evolves to cope 
with changes in costs. In order to extrapolate over ten years, the 
authors simply multiply the first year effects by 10. The results are 
implausible for a dynamic economy as the full static one-year impact is 
unlikely to be the average impact over the course of several years. At 
least theoretically, the economy contains powerful forces pushing it 
towards full employment equilibrium. Therefore, most changes to output 
and employment due to cost or demand shocks tend to be neutralized 
through time. That is, most impacts, negative or positive, will 
approach zero over the long term. Indeed, Inforum's LIFT model produces 
dynamic results that vary from year to year, which is consistent with 
fluctuations in the state of the economy and with short and long term 
expenditure effects. It shows how the employment is reallocated among 
industries and how the economy eventually will return to the baseline, 
or potential, level of employment.
    While the IMPLAN study places the regulatory analysis within the 
context of the overall economy, it does not take full advantage of the 
framework. For instance, given data for gross output in the base year 
it is possible to compute the industry price effect so that the revenue 
shocks can be judged relative to a price elasticity of demand. Instead, 
the study employs an unrealistically large construct of a 5 to 1 
compliance cost to revenue loss. Finally, the IMPLAN model's inability 
to model the long-term properties of the economy severely undermines 
the study's conclusion of long term cost to the economy.

G. Benefits and Net Benefits

    In this section, OSHA discusses the benefits and net benefits of 
the final silica rule. To set out an approach to estimate the benefits, 
the Agency will, in the following sections, estimate the number of 
silica-related diseases prevented as a result of the rule, estimate the 
timing of the potentially avoided diseases, monetize their economic 
value, and discount them. Taking into account the estimated costs of 
the final rule, presented in Chapter V of the FEA, OSHA will then 
estimate the net benefits and incremental benefits of the rule. 
Finally, the Agency will assess the sensitivity of the estimates to 
changes in various cost and benefit parameters.
    This section presents OSHA's quantitative estimates of what rule-
induced benefits would be under certain assumptions. OSHA acknowledges 
that these estimates are heavily influenced by the underlying 
assumptions, and also that the long time frame of this analysis (60 
years) is a source of uncertainty. The assumptions underlying these 
estimates of deaths and morbidity avoided will be discussed in detail 
as they appear in the remainder of this chapter, but the major ones are 
as follows:
     The exposure profile and other industrial profile data 
presented in Chapter III of the FEA reflect both current conditions and 
future conditions (extending over the next sixty years);
     To separate the effects of this new rule from the effects 
of compliance with existing standards, it is assumed that any workers 
currently exposed above the preceding PEL are exposed to levels of 
silica that exactly meet the preceding PEL;
     The rule will result in workers being exposed at the new 
PEL but will never reduce exposures below the new PEL;
     Workers have identical exposure tenures (45 years, except 
where otherwise noted);
     The effects of baseline respirator use on risk are 
ignored; and
     The assumptions inherent in developing the exposure-
response functions discussed in Section VI, presented in Table VI-1 of 
this preamble, are reasonable throughout the exposure ranges relevant 
to this benefits

[[Page 16583]]

analysis. (The reasonableness of these assumptions is discussed in 
Section VI.)
    The first two assumptions are also the basis for the cost analysis 
in Chapter V of the FEA. The basis for the last assumption is discussed 
in greater detail in Section VI of this preamble and will be briefly 
reviewed in this section. It bears emphasis, however, that the sources 
of data for OSHA's benefits analysis are the same as those used in the 
Quantitative Risk Assessment (Section VI of this preamble) and the 
technological feasibility analysis in Chapter IV of the FEA.
    While OSHA did not quantify the benefits of the ancillary 
provisions, consistent with the statute (29 U.S.C. 655(b)(7), section 
6(b)(7)), the Agency finds that these provisions are beneficial and 
necessary in order for the standard to be fully and correctly 
implemented and for the full benefits of the rule to be realized. On 
the whole, OSHA intends the requirements for training on control 
measures, housekeeping, and other ancillary provisions of the rule to 
apply where those measures are used to limit exposures. Without 
effective training on use of engineering controls, for example, it is 
unreasonable to expect that such controls will be used properly and 
consistently. The ancillary provisions found in the rule are generally 
standard and common throughout OSHA regulations.
    The provision requiring exposure assessment in general industry is 
integral to determining the engineering controls and work practices 
needed to control employee exposure to the new PEL, to evaluate the 
effectiveness of the required engineering and work practice controls, 
and to determine whether additional controls must be instituted. In 
addition, monitoring is necessary to determine which respirator, if 
any, must be used by the employee, and it is also necessary for 
compliance purposes.
    The requirement for regulated areas in general industry and 
maritime serves several important purposes including alerting employees 
to the presence of respirable crystalline silica at levels above the 
PEL, restricting the number of people potentially exposed to respirable 
crystalline silica at levels above the PEL, and ensuring that those who 
must be exposed are properly protected. Similarly, the competent person 
requirement in the construction standard will protect bystanders by 
restricting access to work areas only when necessary, benefiting those 
bystanders through reduced exposures.
    Written exposure control plans provide a systematic approach for 
ensuring proper function of engineering controls and effective work 
practices that can prevent overexposures from occurring. OSHA expects a 
written exposure control plan will be instrumental in ensuring that 
employers comprehensively and consistently protect their employees.
    The medical surveillance provisions have the potential to protect 
workers through the early detection of silica-related illnesses and 
will enable employees to take actions in response to information about 
their health status gleaned from medical surveillance. Additionally, by 
requiring medical surveillance to general industry and maritime workers 
exposed at or above the action level, OSHA provides an incentive for 
employers to further reduce exposures, where possible, to avoid 
incurring the costs of medical surveillance.
1. Estimates of the Number of Avoided Cases of Silica-Related Disease
    For reasons described in detail in this preamble, OSHA has adopted 
a PEL of 50 [mu]g/m\3\ in its silica standards covering general 
industry, maritime, and construction, along with an alternative method 
of compliance (Table 1) in construction. Analogous to the estimates in 
the PEA, OSHA has calculated estimates of the benefits associated with 
the PEL of 50 [mu]g/m\3\ for respirable crystalline silica, and 
corresponding Table 1 in construction, by applying the dose-response 
relationships developed in OSHA's quantitative risk assessment (QRA) to 
exposures at or below the preceding PELs.
a. Exposure Profiles
    OSHA determined exposure levels at or below the preceding PELs by 
first developing an exposure profile of current exposures for 
industries with workers exposed to respirable crystalline silica, using 
OSHA inspection and site-visit data, and then applying this exposure 
profile to the total current worker population. The industry-by-
industry exposure profile is presented in Chapter III of the FEA.
    Because OSHA relied solely on measurement of airborne exposures, 
respirator use may result in lower baseline exposures inside the 
respirator than would be indicated by the airborne exposures 
measurements. The extent to which this affects OSHA's benefits 
calculations depends on the extent to which there was baseline 
respirator use in the risk assessment studies OSHA relied on and how 
these studies accounted for respirator use, if they did so at all. OSHA 
reviewed the risk assessment studies it is relying on as well as 
earlier studies that described the source of exposure data for each 
cohort and how exposures were estimated for cohort members to determine 
whether respirator use was accounted for. OSHA found that the 
overwhelming majority of studies did not mention either respirator use 
or how they accounted for respirator use, even though many took place 
in time periods and at exposures levels where some respirator use could 
have been expected. Some studies accounted for use of ``dust controls'' 
but did not state whether these ``dust controls'' included respirator 
use. Two studies (Rando et al. 2001, Document ID 0415), whose exposure 
estimates for North American industrial sand workers were used by 
Hughes et al. (2001, Document ID 1060), and Dosemeci et al. (1993), 
whose exposure estimates for Chinese mine and pottery workers were 
modified and used by Chen et al. (2001, Document ID 0332; 2005, 
Document ID 0985), mention adjusting exposure estimates to account for 
respirator use, but did not discuss in detail how these adjustments 
were calculated. Most studies OSHA relied on, directly or indirectly, 
cover long periods of time, over which respirator use varied. Most 
cover some time after OSHA set a general industry PEL of approximately 
100 [mu]g/m\3\ and required the use of a respirator if that exposure 
level was exceeded. In summary, OSHA does not know the extent of 
respirator use in the risk assessment studies relied on for the 
benefits analysis, nor how they might differ from current respirator 
use. As a result, OSHA is unable to accurately adjust its estimates to 
account for baseline respirator use.
    OSHA also is not able to quantify the effectiveness of respirator 
use. (OSHA regulations provide for assigned protection factors, but 
these are based on ideal conditions rather than real world conditions.) 
It is thus difficult to know how to correct for possible respirator 
use. As will be discussed below, OSHA estimates benefits relative to a 
baseline characterized by compliance with the preceding PEL. The 
preceding PEL in construction and maritime is approximately 250 [mu]g/
m\3\. If respirators have a protection factor of five, then they would 
be equivalent to the new PEL of 50 [mu]g/m\3\ if fully effective at 250 
[mu]g/m\3\. In general industry there is a preceding PEL of 
approximately 100 [mu]g/m\3\. If respirators have a protection factor 
of two, then they would be equivalent to the new PEL of 50 [mu]g/m\3\, 
if fully effective. Beyond this, OSHA does not have the data to 
quantify the effects of respirator use because it is well known that in 
actual practice in work settings, respirators are not always as 
protective

[[Page 16584]]

as the assigned protection factors would indicate. For the purpose of 
estimating the health benefits of the final rule, exposures above the 
relevant preceding PELs were set at the relevant preceding PEL; for 
purposes of comparing the effects of the preceding and the new 
standards, the analysis thus assumes full compliance with both, without 
taking baseline respirator use into account.
    By applying the dose-response relationships from the literature to 
estimates of exposures at or below the preceding PELs across 
industries, it is possible to estimate the number of cases of the 
following diseases expected to occur in the worker population given 
exposures at or below the preceding PELs (the ``baseline''):
     fatal cases of lung cancer,
     fatal cases of non-malignant respiratory disease (NMRD) 
(including silicosis),
     fatal cases of end-stage renal disease, and
     cases of silicosis morbidity.
    Non-fatal cases of lung cancer, NMRD and end-stage renal disease 
were not estimated. In that respect, the estimates of the benefits are 
understated. However, OSHA's benefits calculations do not, for example, 
factor in any impact on the rule's implementation of the following 
aspect of the Agency's enforcement approach: As a general matter, where 
compliance with a standard's requirement clearly creates a new hazard, 
employers can raise a defense that compliance with the requirement is 
not feasible, and OSHA would work with the employer to implement an 
alternative means of protection that does not create a serious 
hazard.\90\
---------------------------------------------------------------------------

    \90\ In FEA Chapter IV, OSHA responds to commenters who have 
stated that safety hazards would increase in the presence of the 
rule (due to, for instance, use of wet methods on roofs) by 
suggesting technologically feasible alternatives, including using 
wet methods or exhaust ventilation on the ground or on platforms or 
scaffolds. Other commenters also described how fall protection on 
roofs was already being used where wet methods are employed.
---------------------------------------------------------------------------

    In a comment suggesting that some reductions in exposures (and thus 
some benefits) were not included in OSHA's analysis, Dr. Ruth 
Ruttenberg noted that ``OSHA/ERG did not consider stomach cancer, 
autoimmune disease, and other cancer and non-cancer health effects of 
silica exposure'' (Document ID 2256, Attachment 4, p. 11). These 
potential benefits were not quantified, for the PEA or FEA, because the 
Agency does not, at this time, have sufficient exposure-response data 
to perform a quantitative risk assessment for these illnesses. The 
Health Effects and Significance of Risk section of this preamble 
contain a more detailed discussion of these potential silica-related 
health effects that were not quantified.
b. OSHA's Method for Using Risk Models and Exposure Profile To Estimate 
Cases Avoided as a Result of the Rule
    The core of OSHA's methodology for benefits analysis is to 
calculate the number of estimated premature deaths and illness cases 
avoided as a result of the new rule. To do this, OSHA estimates the 
expected number of mortality and morbidity cases expected to occur 
under the assumption that the preceding PEL is being met (i.e., those 
workplaces where the preceding PEL is currently exceeded are set equal 
to the preceding PEL), and then subtract the expected number of 
mortality and morbidity cases estimated to occur with the new rule in 
place. OSHA then estimates the numbers of disease cases and deaths that 
would result after the new standard goes into effect (i.e., assuming 
full compliance in that no worker will be exposed in excess of the new 
PEL). For this purpose, OSHA assumes all exposures above the new PEL 
are reduced to the new PEL of 50 [mu]g/m\3\. The difference between 
these estimates represents the numbers of disease cases and deaths that 
the Agency estimates would be avoided as a result of issuing the new 
standard. That is, this approach focuses on calculating estimates 
derived from eliminating those exposures between the preceding PEL and 
the new PEL. As explained later, these estimated mortality and 
morbidity cases avoided are then monetized to comprise the benefits (in 
dollar terms) of the rule.
    By focusing on exposures between the preceding PEL (even for 
workers exposed above the preceding PEL) and the new PEL exclusively, 
and ignoring the possibility that workers' exposures are reduced below 
the new PEL, OSHA's calculations will have a tendency toward 
underestimation. Some exposures may be reduced to below the new PEL of 
50 [mu]g/m\3\ as a result of engineering controls that do more than 
needed. Also, some exposures below the new PEL of 50 [mu]g/m\3\ may be 
reduced further due to ``bystander effects,'' by which those already 
exposed below the new PEL but working near other exposed workers would 
have their exposures reduced further.
    In order to estimate the number of deaths prevented, OSHA uses a 
lifetime risk model, which is a mathematical framework that explicitly 
follows workers from the beginning of their work lives until 
retirement. Workers are assumed to start work at age 20 and work 
continuously until age 65, resulting in a 45-year work life, and then 
assumed to live another 15 years post-retirement, or until age 80. This 
estimate is useful because the OSH Act requires OSHA to examine 
exposures for an entire working life. Shorter job tenures will be 
discussed further below.
    Using this model, OSHA calculates the workers' cumulative workplace 
exposures to silica, and estimates the probability of their dying each 
year from silica-related diseases. The model also establishes the 
background probability of the workers' dying from non-silica-related 
causes. The increase in the workers' probability of dying due to 
cumulative silica exposure in the workplace is added to this background 
probability. As will be explained in more detail later, the difference 
in these probabilities is used to form the basis for estimating the 
number of illnesses and deaths due to silica exposures as they 
currently exist and the estimated number of illnesses and deaths that 
would be avoided when the standard is fully in effect, assuming full 
compliance.
    The background, age-specific survival probabilities are based on 
the current (2011) U.S. (male) population, the latest year for which 
age-specific all-cause mortality statistics are available.\91\ The

[[Page 16585]]

exposure-response functions for different diseases, which relate 
cumulative silica exposure and increased probabilities of respective 
disease endpoints, are drawn from specific studies discussed in this 
preamble, Section VI--Final Quantitative Risk Assessment and 
Significance of Risk.\92\ Estimates of the number of cases of silicosis 
prevented by the new standard were also based on cumulative risk models 
taken from several morbidity studies, but were not used in life table 
analyses as was done for mortality (see Section VI of this preamble, 
Final Quantitative Risk Assessment and Significance of Risk). The 
exposure levels used in the model cover the U.S. exposure profile as 
presented in Table III-9 in Chapter III Industry Profile of the FEA. 
OSHA's exposure profiles for general industry and maritime and for 
construction contain the estimated numbers of employees exposed within 
specific bands of exposure levels: below 25 [mu]g/m\3\, 25 to 50 [mu]g/
m\3\, and above 50 [mu]g/m\3\ (in bands of 50 [mu]g/m\3\ to 100 [mu]g/
m\3\, 100 [mu]g/m\3\ to 250 [mu]g/m\3\, and above 250 [mu]g/m\3\, 
whenever any of these bands are above the preceding PEL, OSHA lowered 
the estimate for the band to the preceding PEL).
---------------------------------------------------------------------------

    \91\ Overall, approximately 3 percent of all construction 
workers are women. (BLS, 2014--Labor Force Statistics from the 
Current Population Survey, available at http://www.bls.gov/cps/cpsaat11.pdf). There is no comparable breakdown for manufacturing 
occupations as a whole but, for selected occupations for which data 
are available, women are always fewer than 15 percent of the 
relevant manufacturing workforce. OSHA used background mortality 
rates for the U.S. male population because the cohorts in the key 
studies used in the Agency's quantitative risk assessment were 
composed overwhelmingly of male workers. OSHA used the exposure-
response models from these studies in a life table analysis to 
estimate excess risk of disease mortality from exposure to 
respirable crystalline silica after accounting for competing causes 
of death due to background causes. Because, in most key studies, the 
exposure-response models were built using data from male workers 
only, it is unknown how these models would change for female 
workers, or for mixed-gender populations, as it is not clear that 
females would react to the silica exposure in the same exact way as 
males. There is no such model data available for these cohorts. 
Furthermore, OSHA believes that use of all-cause mortality data for 
the U.S. population as a whole is not appropriate since the working 
populations studied in the cohort studies, as well as the present 
population of workers covered by the rule, are overwhelmingly male 
and do not reflect the nearly equal proportion of males and females 
represented by the all-cause mortality data for the U.S. population 
as a whole. If one were to assume that the exposure-response model 
for female workers was the same as that for male workers, then the 
resulting relative risk (RR, the ratio of the risk of disease 
mortality occurring in the exposed to the risk of disease mortality 
occurring in the unexposed) for a particular cumulative exposure 
would be the same. Because the risk of disease mortality in the 
exposed population is calculated by multiplying the RR by the 
background risk in the unexposed population, the risk of mortality 
in the exposed population would be different between females and 
males and would depend upon the background gender-specific disease 
risks. Because the background cause-specific (e.g., lung cancer or 
NMRD) mortality for females is generally lower than that for males, 
the Agency would expect that the predicted risk of mortality to 
exposed females may be slightly lower than that for exposed males. 
On the other hand, this effect may be offset by female workers' 
greater likelihood of surviving to the advanced age groups in which 
silica-related diseases most typically appear in severe forms and 
become a cause of death. Given the absence of exposure-response 
models for female workers, which are required to estimate a proper 
RR of disease for females, it is impossible to make any sound 
conclusion on how the risk estimates would change for female 
workers.
    \92\ Specifically the low estimate for lung cancer uses 
estimates from ToxaChemica (2004, Document ID 0469), the high 
estimate for lung cancer uses Attfield and Costello (2004, Document 
ID 0543), the renal disease estimate uses Steenland, Attfield, and 
Mannetje (2002) (Document ID 1089), the morbidity estimate for 
silicosis uses Buchanan, Miller, and Soutar (2003, Document ID 
0306), and the mortality estimate for silicosis uses Mannetje, et. 
al. (2002, Document ID 1089). See Section VI--Final Quantitative 
Risk Assessment and Significance of Risk in this preamble for more 
discussion.
---------------------------------------------------------------------------

    The results in Table III-9 in the FEA represent average daily 
exposures in the risk model for general industry and maritime. In 
construction, occupational exposure is commonly intermittent (i.e., not 
occurring every workday), necessitating an adjustment to accurately 
estimate these workers' cumulative exposure and risk. Workers in the 
construction sector perform a multitude of tasks, only some of which 
involve silica exposure. OSHA's estimated exposure levels represent the 
8-hour time-weighted average of exposure on days when workers perform 
tasks involving silica exposures. However, to account for the fact 
that, in most affected construction occupations, workers do not do such 
tasks every day, the cumulative exposure estimate for these workers 
needed to be adjusted. To account for this intermittent exposure, the 
risk model uses an adjustment factor which estimates the percentage of 
days in which a worker will typically perform tasks that generate 
silica exposures. These adjustment factors are generally based on the 
proportion of time workers perform silica-generating activities along 
with associated work crew sizes.\93\ So, for example, if, on average, a 
group of workers is estimated to spend 20 percent of its time 
performing tasks involving silica exposure, the model multiplies the 
base exposure level--the exposure that the group of workers is 
estimated to have based on the exposure profile--by this 20 percent. In 
the Agency's model, this adjustment factor is calculated as the total 
number of full time equivalent days that affected employees spend on 
silica-related tasks divided by total affected employment as shown in 
Chapter III of the FEA. For all construction occupations other than 
hole drillers using hand-held drills, OSHA calculated an FTE adjustment 
factor of 28 percent that was derived from the exposure profile. Hole 
drillers using hand-held drills have a large number of employees and an 
extremely low adjustment factor as compared to all other occupations. 
Because the risk models are nonlinear, averaging such disparate groups 
together provides unrepresentative results and therefore, this 
occupation has its risk calculated separately. For hole drillers using 
hand-held drills, OSHA calculated an adjustment factor of 3.5 percent.
---------------------------------------------------------------------------

    \93\ Detailed methodology and estimates for each occupation are 
discussed in the construction engineering control cost section in 
Chapter V of the FEA, in the subsection entitled ``Aggregate `Key' 
and `Secondary' Labor Costs for Representative Projects.''
---------------------------------------------------------------------------

    In order to calculate the number of expected and avoided cases for 
each health outcome, OSHA assumes that all workers whose exposures fall 
within a band are exposed the same and assigns the average of all 
individual exposure observations within the relevant band (i.e., the 
mean exposure) as the single point estimate within each band.\94\ This 
point estimate of exposure is then used with the associated risk 
estimate for each health outcome, which is multiplied by the estimated 
number of workers exposed within the exposure band to calculate the 
number of workers who experience that health outcome in the absence of 
the new rule. For workers currently exposed above the new PEL, OSHA 
assumes that their post-rule exposures will be lowered to the new PEL 
of 50 [micro]g/m\3\. This reflects the fact that the Agency is taking 
no benefits for reducing exposure above the previous PELs to the 
previous PELs. The analysis starts from a baseline of the previous 
PELs. A similar calculation is then performed at these new exposure 
levels for these currently overexposed workers: The numbers of workers 
exposed within each exposure band of the post-rule exposure profile is 
then multiplied by the associated risk estimates for each health 
outcome to yield estimates of the numbers of disease cases and 
fatalities that will occur after the standard is implemented. Finally, 
subtracting this post-implementation number of deaths and disease cases 
from those estimated under baseline (pre-rule) conditions yields an 
estimate of the number of deaths and illness cases averted due to the 
standard.
---------------------------------------------------------------------------

    \94\ Individual exposure data are presented within various 
sections of Chapter IV, Technological Feasibility, of the FEA. All 
individual observations are presented in Technical and Analytical 
Support for OSHA's Final Economic Analysis for the Final Respirable 
Crystalline Silica Standard: Excel Spreadsheets Supporting the FEA, 
available in Docket OSHA-2010-0034 at www.regulations.gov.
---------------------------------------------------------------------------

    As an example, Table VII-23-1 presents the summary calculations for 
a risk model that produces one estimate of the number of lung cancer 
deaths avoided by the revised standard for workers in general industry 
if they were all exposed to silica for 45 years (this uses the 
ToxaChemica 2004 risk model of lung cancer deaths avoided).

[[Page 16586]]

[GRAPHIC] [TIFF OMITTED] TR25MR16.095

    In Table VII-23-1, the total General Industry population at risk 
for excess lung cancer is 291,019. There are 142,071 workers in the 
range of silica exposure of below 25 [micro]g/m\3\, 51,377 workers 
exposed between 25 and 50 [micro]g/m\3\, etc. The ``Model Exposure 
Level-Baseline'' row provides the mean exposure level within each 
range, which is the point estimate of exposure for which the associated 
lifetime risk estimate is used to estimate the number of lung cancer 
deaths that occur among workers exposed within each exposure range. For 
example, from the exposure profile, the mean exposure for workers in 
General Industry who are exposed below 25 [micro]g/m\3\ is 14 [micro]g/
m\3\, and the risk of lung cancer for all workers in this exposure band 
is calculated from this average exposure of 14 [micro]g/m\3\. Though 
the exposure profile includes 28,297 workers exposed in the range of 
100-250 [micro]g/m\3\ and 28,443 workers exposed above 250 [micro]g/
m\3\, to estimate the number of baseline lung cancer deaths, those 
workers' exposure levels are set at

[[Page 16587]]

the preceding PEL of 100 [micro]g/m\3\. In this example, estimated 
benefits due to the new PEL do not include any benefits to workers for 
their exposures being reduced to the preceding PEL; only those benefits 
associated with the exposure levels being reduced from the preceding 
PEL or lower to the new PEL are included in the estimates. The row 
labeled ``Model Exposure Level-50 PEL'' shows the expected exposures 
among workers that result after the standard is promulgated. Exposures 
of workers exposed below 50 [micro]g/m\3\ are expected to remain 
unchanged while the exposures of all workers who are currently exposed 
above 50 [micro]g/m\3\ are expected to be reduced to the new PEL of 50 
[micro]g/m\3\.\95\
---------------------------------------------------------------------------

    \95\ For the purposes of estimating costs and benefits, OSHA 
assumes full compliance with all applicable OSHA standards.
---------------------------------------------------------------------------

    Table VII-23-1 also presents the estimated excess risk of lung 
cancer per 1,000 workers for each exposure band and the number of lung 
cancer deaths that would occur among workers exposed within each 
exposure band for 45 years. For example, among workers exposed within 
the lowest exposure band, the lifetime risk model estimates an 
increased risk of lung cancer above the background mortality risk of 
14.7 deaths per 1,000 workers at a constant exposure to 14 [micro]g/
m\3\ silica for 45 years. Multiplying this risk estimate by the number 
of workers at risk in that exposure band (142,071) yields an estimated 
2,084 lung cancer deaths. Doing the same across the various baseline 
exposure level bands results in an estimated baseline total of 5,021 
lung cancer deaths due to exposure to silica for the population of 
workers at risk. The table shows similar estimated lung cancer risks 
and estimated numbers of deaths in the post-standard scenario. For all 
workers whose baseline 45-year exposures are at or above 50 [micro]g/
m\3\, the estimated risk of lung cancer associated with exposure at the 
new PEL of 50 [micro]g/m\3\ is 19.0 per 1,000 workers. Multiplying this 
risk by the number of workers exposed to silica at levels between 50 
and 100 [micro]g/m\3\ (41,596), for example, yields an estimated 776 
deaths occurring in this group for the post-standard scenario. Doing 
the same for each exposure band for the post-standard scenario and 
summing across all exposure bands, the number of estimated excess lung 
cancer deaths post-standard is 4,858. The next two rows show the 
difference between the baseline and the post-standard scenarios, both 
for lung cancer death risks (``differential lung cancer death rate'') 
and numbers of deaths (``lung cancer deaths averted''). The final total 
number of lung cancer deaths averted is 163. Dividing by the analytic 
time horizon of 45 years results in about 4 annual deaths averted.
    The preceding example assumes a constant exposure level each year 
for 45 years. Elsewhere in this chapter, OSHA examines what would 
happen if the day-to-day exposure remains the same but job tenure is 
shorter. In order to have a valid comparison, OSHA compares each 
scenario to what is estimated to happen over 45 years. All job tasks, 
and hence cumulative exposure, do not change with decreased job tenure; 
they are just spread over more workers. Thus, if OSHA were to examine a 
job tenure of 25 years, almost twice as many workers would be exposed 
for almost half as long as for the 45-year assumption. With a strictly 
proportional (linear) risk function the benefits of having half the 
exposure for twice the number of workers would exactly offset each 
other and final benefits would be the same. Hence the net effect of 
such changes is directly related to non-linearities in the various 
lifetime risk models.
c. Results for Cases Avoided
    OSHA received a number of comments concerning the Agency's 
preliminary risk assessment and discussion of the health effects of 
silica in this preamble to the proposed rule. Those comments are 
discussed in detail in Sections V (Health Effects) and VI (Final 
Quantitative Risk Assessment and Significance of Risk) of this preamble 
to the final rule.
    OSHA examined the various lung cancer risk models presented in its 
QRA to estimate the benefits of lowering the PEL. As can be inferred 
from Table VI-1 of the Final QRA, the ToxaChemica, Inc. (2004, Document 
ID 0469) log-linear model estimated the lowest estimate of lung cancer 
cases avoided from lowering the PEL to 50 or 100 [mu]g/m\3\, whereas 
the Attfield and Costello (2004, Document ID 0543) model estimated the 
highest number of lung cancer cases avoided. The remainder of the 
studies indicated an intermediate reduction in risk. OSHA used the 
ToxaChemica 2004 (log-linear model) and Attfield and Costello studies 
to characterize a range of estimated lung cancer reduction, 
acknowledging that neither of these estimates captures the full range 
of uncertainty associated with the models and data used.
    Table VII-24 shows the range of modeled estimates for the number of 
avoided fatal lung cancers for PELs of 50 [mu]g/m\3\ and 100 [mu]g/m\3\ 
for the scenario in which workers are uniformly exposed to silica for 
45 years. At the final PEL of 50 [mu]g/m\3\, the modeling approach 
yields estimates of 2,921 to 8,246 lung cancers prevented over the 
lifetime of the worker population, with a midpoint estimate of 5,584 
fatal lung cancers prevented. This is the equivalent of between 65 and 
183 cases avoided annually, with a midpoint estimate of 124 cases 
avoided annually, given a 45-year working life of exposure.
    Following Park (2002, Document ID 0405), as discussed in the 
Agency's QRA, OSHA's estimation model suggests that the final PEL of 50 
[mu]g/m\3\ would, in the scenario in which workers are uniformly 
exposed to silica for 45 years, prevent 14,606 fatalities over the 
lifetime of the worker population from non-malignant respiratory 
diseases arising from silica exposure.\96\ This is equivalent to 325 
fatal cases prevented annually. Some of these fatalities would be 
classified as silicosis, but most would be classified as other 
pneumoconiosis and chronic obstructive pulmonary disease (COPD), which 
includes chronic bronchitis and emphysema. That is one reason why we 
would expect this estimate to exceed the count based solely on death 
certificates (for instance, in 2013, CDC's count based on state-
provided vital records is 111 deaths annually from silicosis in the 
United States).
---------------------------------------------------------------------------

    \96\ Park et al. (2002, Document ID 0405) also found that silica 
exposure was responsible for a significant number of deaths that had 
been attributed to diseases other than silicosis.
---------------------------------------------------------------------------

    Certain commenters argued that the recent CDC count of silicosis 
mortality from death certificates is evidence that OSHA's benefits were 
overestimated.
    Some commenters, such as the American Chemistry Council and Faten 
Sabry, Ph.D., representing the Chamber of Commerce, argued--based on 
the numbers of silicosis-related deaths recorded in recent years 
reported in mortality surveillance data--that OSHA overestimated the 
estimated benefits of the standard (Document ID 2263, p. 57; 3729, p. 
1; 2288, Appendix 6; 4209, pp. 3-4). Dr. Sabry stated that the 52 
deaths reported by the CDC in 2010 where silicosis was identified as an 
underlying cause of death were considerably fewer than the number of 
silicosis-related deaths that OSHA claimed would be avoided once the 
proposed standard becomes fully implemented. Dr. Sabry concluded, 
``[s]o, by OSHA's calculation, reducing the PEL to 50 [micro]g/m\3\ 
will prevent more silicosis-related deaths than actually occur in the 
United States today--which suggests that OSHA's risk assessment is 
faulty'' (Document ID 2288, Appendix 6). The

[[Page 16588]]

National Utility Contractors Association (NUCA) made the same argument 
when it asserted: ``OSHA predicts that this proposed rule will prevent 
approximately 600 silica related deaths per year, but the CDC is 
recording less than 100 deaths per year'' (Document ID 3729, p. 1). The 
National Federation of Independent Business also argued that OSHA 
estimated 375 prevented cases of silicosis that would have led to 
deaths, but the CDC reported only about 150 deaths per year where 
silicosis was the underlying cause or a contributing factor, causing 
OSHA to overestimate lives saved due to the standard by about 150 
percent (Document 2210, Attachment 1, p. 3).
    OSHA disagrees that the silicosis mortality surveillance data alone 
provides evidence that OSHA has overstated the quantitative benefits of 
the rule. OSHA derived its benefits estimates from exposure data 
presented in the Industry Profile chapter of the FEA and from its 
quantitative risk assessment, which is based on epidemiological data 
that quantify relationships between exposure and disease risk. OSHA 
relied on these estimates to estimate the number of silicosis-related 
deaths and illnesses that would occur absent a revised standard and the 
number of deaths that would be avoided by promulgation of such a 
standard. From this analysis, OSHA estimated that 325 deaths from 
silicosis and other non-malignant lung disease and 918 silicosis 
morbidity cases are estimated to be avoided annually once the full 
effects of the standards are realized. The 52 deaths cited by Dr. Sabry 
appears to refer to only the number of deaths with silicosis coded as 
the ``underlying'' cause of death on death certificates, and does not 
include deaths coded with silicosis as a ``contributing'' cause. 
Combined with the deaths where silicosis is coded as a ``contributing'' 
cause, in this case 49, CDC/NIOSH reported a total of 101 deaths where 
silicosis was either an underlying cause of death or a contributing 
cause of death.
    OSHA's model does not only count fatalities related to silicosis. 
OSHA's estimate of the impact of exposure to respirable crystalline 
silica includes deaths from other diseases (lung cancer, non-malignant 
respiratory disease such as chronic bronchitis and emphysema, and end-
stage renal disease) that, according to scientific evidence, can be 
caused by exposure to respirable crystalline silica (Document ID 1711; 
2175, p. 2). OSHA also estimated, based on the Park study discussed 
previously, that 325 cases of fatal non-malignant respiratory diseases 
associated with exposure to silica, including, but not limited to 
silicosis, that would be prevented annually due to the final standard. 
Thus, OSHA's estimates of the numbers of deaths prevented that are due 
to non-malignant respiratory disease are not comparable to surveillance 
statistics that only capture silicosis as a cause of death. 
Furthermore, Dr. Sabry's comments are primarily focused on the 
hydraulic fracturing industry, which only recently became a major 
source of silica exposure, where most of the effects of current 
exposures will likely not be seen for a number of years, underlining 
why this analysis of past trends is not instructive for epidemiological 
estimates.
    In response to NUCA's comparison of OSHA's estimate of 679 deaths 
avoided to the estimate of fewer than 100 deaths from the surveillance 
data, the Agency again points out that the model accounts for causes of 
death other than those resulting from silicosis and therefore reported 
to CDC/NIOSH in the surveillance data. Therefore, NUCA's comparison is 
faulty because focusing exclusively on silicosis mortality fails to 
capture silicosis morbidity, as well as mortality and morbidity 
resulting from other diseases related to silica exposure, including 
lung cancer, other non-malignant respiratory disease such as chronic 
bronchitis and emphysema, and renal disease (see Section VI, Final 
Quantitative Risk Assessment and Significance of Risk, Table VI-1).
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    George Kennedy of the National Utilities Contractor's Association 
makes a similar ``apples and oranges'' error in his comment:

    OSHA predicts that this rule will prevent approximately 600 
silica-related deaths per year. But how is this possible if the CDC 
is reporting less than 100? (Document ID 3583, p. 2240)

    Mr. Kennedy's comment is based on comparing CDC counts of 
documented silicosis fatality cases, but this count is not a report on 
all silica-related deaths. The Agency's articulated need for the 
standard, however, is based on the finding that silica exposure results 
in an array of adverse, mutually independent health endpoints. In 
contrast, the CDC estimate deals with a small part of the overall 
health risk from silica exposure.
    As also discussed in the Agency's QRA, OSHA finds that workers with 
higher cumulative exposures to silica are at elevated risk of lung 
cancer, end-stage renal disease, and non-malignant respiratory 
diseases. Based on the midpoint of the lower high-end estimate 
(Attfield and Costello, 2004, Document ID 0543) and a higher low-end 
estimate (ToxaChemica log-linear model, Document ID 0469), OSHA's 
estimation model estimates that the new PEL of 50 [mu]g/m\3\ would, in 
the scenario in which workers are uniformly exposed to silica for 45 
years prevent 5,584 cases of lung cancer, or about 124 cases annually 
upon reaching ``steady state'' (see later discussion of this concept) 
in 60 years. Based on Steenland, Attfield, and Mannetje (2002, Document 
ID 1089), OSHA's estimation model estimates that the final PEL would 
prevent 8,689 cases of end-stage renal disease, or about 193 cases 
annually in steady state. And based on Park (2002, Document ID 0405), 
OSHA's estimation model estimates that the new PEL would prevent 14,606 
cases of non-malignant respiratory diseases (including silicosis) over 
the lifetime of 45 cohorts' worth of worker population, or about 325 
cases annually in steady state, of which 2,970 (66 annually) are 
attributable to diagnosed cases of silicosis, based on Mannetje (2002, 
Document ID 1089).
    Combining the three major fatal health endpoints--lung cancer, non-
malignant respiratory diseases, and end-stage renal disease--OSHA's 
modeling approach yields estimates that the new PEL would prevent 
between 26,216 and 31,541 premature fatalities over the lifetime of the 
current worker population, with a midpoint estimate of 28,879 
fatalities prevented. This is the equivalent of between 583 and 701 
premature fatalities avoided annually, with a midpoint estimate of 642 
premature fatalities avoided annually, given a 45-year working life of 
exposure.
    In addition, the final silica rule is estimated to prevent a large 
number of cases of silicosis morbidity. Table VII-25 is designed to 
compare available estimates of actual silicosis cases to the estimates 
generated by OSHA exposure profile and models. The first set of rows 
compares present estimates of 2/1 and the second set of rows estimates 
of 1/0 cases of silicosis generated by various risk models using OSHA's 
exposure profile. Going across, the first columns are for a tenure 
length of 45 years, the second set for a tenure length of 13 years. 
Then below in the second panel, the final set of rows is based on 
Rosenman, et al. (2003, Document ID 1166) estimates of actual silicosis 
cases, generated with an alternative modeling approach. To be 
consistent with OSHA's jurisdiction, OSHA revised Rosenman's estimate 
to remove workers not in OSHA's jurisdiction, such as miners. The lower 
panel, based on Rosenman, et al. (Document ID 1166), shows, assuming 45 
years of exposure, that between 2,700 and 5,475 new cases of silicosis, 
at an ILO x-ray rating of 1/0 or higher, are estimated to occur 
annually at current exposure levels as a result of silica exposure at 
establishments within OSHA's jurisdiction (i.e., excluding miners).\97\ 
The various models OSHA used yield estimates of between 836 and 8,011 
cases, assuming 45 years of exposure and between 393 and 10,107 cases 
assuming 13 years of exposure at an ILO x-ray rating of 1/0 or higher. 
OSHA's risk models for morbidity using OSHA's exposure profile are thus 
somewhat consistent with epidemiologically based estimates of silicosis 
cases though some are a bit over the epidemiological estimates. When a 
job tenure of 13 years is assumed, the table shows that for most 
models, as compared to the 45 year job tenure analysis, the results are 
a lower numbers of cases, while other models yield estimates of cases 
within the range estimated by Rosenman for U.S. workers other than 
miners (who are outside OSHA's jurisdiction.) There are, however, 
exceptions. The estimated number of cases for some models falls below 
Rosenman's estimates. On the other hand, two models show an increased 
number of cases which are above the range of Rosenman's estimates. This 
is a result of very high rates of cases expected to occur in persons 
exposed at levels above the preceding PELs. Since OSHA does not 
estimate benefits to workers exposed at levels above the preceding 
PELs, any estimated increase in cases among such workers will not 
affect OSHA's benefits analysis.
---------------------------------------------------------------------------

    \97\ Rosenman indicated that the underlying cases of silicosis 
morbidity have changed little over time, testifying that data from 
the National Intake Survey indicated that the nationwide number of 
hospitalizations where silicosis was one of the discharge diagnoses 
has remained constant, with 2,028 hospitalizations reported in 1993 
and 2,082 in 2011 (Document ID 3425, p. 2).

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    A number of commenters took issue with the general idea that 
silicosis is an occupational health problem for workers whose exposures 
to silica did not exceed the preceding PELs. These commenters typically 
pointed to the significant decline in the number of silicosis deaths 
reported by the CDC in the last few decades.
    OSHA does not find these comments persuasive. As explained in depth 
in the Health Effects and Risk Assessment sections of this preamble, 
while the Agency welcomes any apparent decline in silicosis cases, the 
Agency has substantial evidence that significant risk remains at 
preceding PELs. The commenters do not account for the undercounting of 
silicosis deaths from death certificates, as demonstrated by Rosenman 
(Document ID 1166] and others; nor do they address other health 
endpoints beyond fatal silicosis. Although the decline in reported 
cases may indicate the Agency's success up to this point in reducing 
the incidence of silicosis, it cannot be taken as an absolute measure 
of how many silica-related disease cases currently exist in the 
population. Most silicosis cases are not fatal--given that the total 
cases of silicosis have apparently remained largely constant, fewer 
silicosis fatalities may mean that more individuals are living with 
silicosis for longer periods while ultimately dying of other 
causes.\98\
---------------------------------------------------------------------------

    \98\ As indicated previously, Rosenman found that the underlying 
cases of silicosis morbidity have changed little over time, 
remaining constant, even while reported fatalities have declined 
(Document ID 3425, p. 2).
---------------------------------------------------------------------------

    While OSHA has estimated morbidity from silicosis, it has not 
attempted to estimate the number of morbidity cases

[[Page 16592]]

from these other health endpoints. Including these other endpoints 
would increase estimates of the number of overall cases avoided.
    As summarized in Table VII-25, OSHA expects that, in the scenario 
in which workers are uniformly exposed to silica for 45 years, the 
silica rule will eliminate the majority of 1/0, 1/1, and 1/2 silicosis 
cases. However, the Agency has not included the elimination of these 
less severe silicosis cases in its estimates of the monetized benefits 
and net benefits of the final rule. Instead, as shown above in Table 
VII-24, OSHA focused its morbidity-only benefits and related net 
benefits analysis exclusively on the number of silicosis cases reaching 
the more severe levels of 2/1 and above (moderate-to-severe silicosis, 
using the ILO method for assessing severity). As discussed in the 
Agency's QRA, OSHA estimates that the new PEL of 50 [mu]g/m\3\ for the 
current worker population would, in the scenario in which workers are 
uniformly exposed to silica for 45 years, prevent 41,293 cases of 
moderate-to-severe silicosis (2/1 or more) over a working life, or 
about 918 cases prevented annually.\99\
---------------------------------------------------------------------------

    \99\ The unfiltered count of morbidity cases is reported only in 
Table VII-25. The Agency believes the actual number of morbidity-
only cases prevented by the standard in the scenario in which 
workers are uniformly exposed for 45 years is somewhere between 918 
and 984 cases annually, using Mannetje (2002) (Document ID 1089) to 
estimate the number of prevented silicosis fatalities (66) and 
excluding these fatalities from the estimated ``morbidity-only'' 
cases. While the Agency received no comment on its methodology for 
counting morbidity cases, in preparing the FEA OSHA discovered that 
the simultaneous accounting for morbidity in Buchanan's study of 
coal miners (2003, Document ID 0306) and pre-mortality morbidity in 
Park (2002) (Document ID 0405) could result in a potential double-
counting of morbidity valuation (discussed later in this chapter), 
as some of the Buchanan's cases diagnosed with 2/0+ silicosis at 
retirement could ultimately proceed to death. A precise estimate of 
the morbidity-only cases is not possible, as Buchanan also excluded 
a number of cases where the workers had already died, possibly from 
silicosis, so that Buchanan was, in turn, likely underestimating the 
total lifetime morbidity risk from silicosis. By relying on 
Mannetje, OSHA avoids any potential double counting of benefits.
---------------------------------------------------------------------------

    As previously discussed, OSHA based its estimates of reductions in 
the number of silica-related diseases using estimates that reflect a 
working life of constant exposure for workers who are employed in a 
respirable crystalline silica-exposed occupation for their entire 
working lives, from ages 20 to 65.\100\ In other words, these estimates 
reflect an assumption that workers do not enter or exit jobs with 
silica exposure mid-career or switch to other exposure groups during 
their working lives. While the Agency is legally obligated to examine 
the effect of exposures from a 45-year working lifetime of 
exposure,\101\ for purely informational purposes, the Agency also 
alternatively examined the effect of assuming that workers are exposed 
to silica for three other tenure lengths: 25, 13, and 6.6 working years 
(see Table VII-26a through Table VII-26c for number of cases and Table 
VII-28a through Table VII-28d for monetary benefits for all four tenure 
levels).
---------------------------------------------------------------------------

    \100\ In construction, the analysis assumes that while workers 
gain additional exposure annually, they are not necessarily exposed 
to silica constantly, depending upon the demands of the job.
    \101\ Section 6(b)(5) of the OSH Act states: ``The Secretary, in 
promulgating standards dealing with toxic materials or harmful 
physical agents under this subsection, shall set the standard which 
most adequately assures, to the extent feasible, on the basis of the 
best available evidence, that no employee will suffer material 
impairment of health or functional capacity even if such employee 
has regular exposure to the hazard dealt with by such standard for 
the period of his working life.'' Given that OSHA must analyze 
significant risk over a working life, the Agency estimated benefits 
for the affected population over the same period.
---------------------------------------------------------------------------

    Table VII-26a presents cases for a worker exposed for 25 years. 
While each individual worker is estimated to have less cumulative 
exposure under the 25-years-of-exposure assumption, in fact 56 percent 
(25/45) as much, the effective exposed population over time is 
proportionately increased (due to the turnover of workforce for a 
constant number of jobs, and hence total exposure), over the same time 
period. A comparison of Table VII-26a to Table VII-24, reflecting 
exposures over 25 working years versus 45 working years, shows 
variations in the number of estimated prevented cases by health 
outcome. Estimated prevented cases of fatal end-stage renal disease are 
higher in the 25-year model, whereas cases of fatal non-malignant 
respiratory disease and silicosis morbidity are lower. In the case of 
lung cancer, the effect varies by model, with a decrease in the 
Attfield and Costello, 2004 higher estimate (Document ID 0543) and an 
increase in the ToxaChemica, 2004 lower estimate (Document ID 0469). 
Looking at overall totals, the midpoint estimate of the number of 
avoided fatalities under the new PEL of 50 [mu]g/m\3\ is 642 for 45 
years, increasing to 772 for 25 years. For total morbidity, there 
instead is a decrease: from 918 cases avoided for 45 years down to 443 
cases avoided for 25 years, Table VII-26b presents results for 13 years 
of exposure. For a 13 year job tenure, the midpoint for the number of 
fatalities avoided is 982 while the total number morbidity cases 
avoided is 246. Finally, Table VII-26c presents the results for 6.6 
years of exposure. In this scenario, the midpoint for the number of 
fatalities avoided is 1,382 and the total number of morbidity cases 
avoided is 194. Looking across the tenure results shows that midpoint 
mortality significantly increases with lower tenure, while total 
morbidity has a large decrease with lower tenure.
    A commenter, Joseph Liss, objected to the Agency's approach of 
simultaneously increasing the estimated exposed population--not because 
it was technically incorrect, but because it makes it harder to see the 
difference in risk to a particular exposed population (Document ID 
1950, pp. 16-19).

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    OSHA reported in the PEA that in the construction industry, which 
has an unusually high rate of job turnover compared to other 
industries, BLS data show that the mean job tenure with one's current 
employer is 6.6 years (BLS, 2010a, Document ID 1620), and the median 
age of construction workers

[[Page 16597]]

in the U.S. is 41.6 years (BLS, 2010b, Document ID 1672). OSHA further 
noted that BLS does not have data on occupational tenure within an 
industry, but that the Agency would expect that job tenure in the 
construction occupations as a whole would be substantially greater than 
the job tenure with a worker's current employer. None of the commenters 
disagreed. Furthermore, many workers may return to the construction 
industry after unemployment or work in another industry. Job tenure 
with the current employer, however, is longer in the other industries 
affected by the silica rule (BLS, 2010a, Document ID 1620).
    Dr. Ronald Bird, submitting a comment on behalf of the U.S. Chamber 
of Commerce--as well as an unaffiliated commenter, Joseph Liss--
suggested that OSHA's estimates of disease cases prevented from 45 
years of silica exposure is unrepresentative of the typical tenure of 
workers affected by the standard, particularly in construction 
(Document ID 2368, p. 18; Document ID 1950, pp. 15-19). Dr. Bird 
suggested that workers will routinely change occupations in the course 
of their lifetime. From a probabilistic standpoint, he calculated that 
workers would, on average, likely work in an occupation for less than 
six years. The comments directly from the Chamber of Commerce go 
further, to say that ``[n]o such 45-year career silica exposures exist 
in today's working world . . .'' (Document ID 2288, p. 11).
    The article (Rytina, 1983, Document ID 2368) that Dr. Bird cited 
for his data on occupational turnover provides data that refute the 
assumptions of Dr. Bird's model. While Dr. Bird assumes that 
occupational turnover is constant without regard to age or length of 
occupational experience, the Rytina article states:

    Not surprisingly, occupational mobility rates declined sharply 
with age . . . The rate for workers age 35-44 was less than one 
fourth as high as that for workers 18 and 19 years of age. * * * 
[O]ccupational change among older workers occurs less frequently 
because of attachments to a particular occupation or the risks of 
losing income, job security, and pension rights, which might 
accompany an occupational shift (Rytina, 1983, Document ID 2368, p. 
5).

    Furthermore, the Rytina article shows that among workers 45 to 54 
years of age, 16.5 percent of workers have been in the same occupation 
for 25 years or more, and among workers 55 and older, 32.9 percent have 
been in the same occupation for 25 years or more. By comparison, Dr. 
Bird's model suggests that, regardless of age, no more than 13 percent 
of workers will remain in a given occupation for more than 20 years.
    Two commenters also provided evidence of the average tenures of 
their workers that is contrary to Dr. Bird's estimates. The National 
Industrial Sand Association (NISA) noted, ``many NISA member company 
employees work at their workplaces for all or much of their worklives. 
In 2004, a study calculated the mean tenure for NISA member company 
employees fitting the definition of the study's cohort to be 19.7 
years'' (Document ID 2195, p. 19). Southern Company, an electric 
utility, noted that it ``has approximately 8000 employees in job titles 
performing activities with potential exposures to silica-containing 
materials. The average tenure for these employees is 17 years; 37% of 
these employees have over 20 years work experience'' (Document ID 2185, 
p. 3).
    Other commenters provided evidence to refute the Chamber of 
Commerce claim that that 45-year career silica exposures no longer 
exist in today's working world (Document ID 2288, p. 11). During the 
public hearing, participants on a panel comprised of members of the 
International Union of Bricklayers and Allied Craftworkers (BAC) were 
asked if they had colleagues who had worked longer than forty years in 
their trade. All six of the participants affirmed that they did 
(Document ID 3585, Tr. 3053). Further, several labor groups submitted 
evidence of lengthy worker tenure. The BAC noted that:

    A review of our International Pension Fund records documented 
116 individuals who have worked for 40 years or more. We consider 
this figure to understate the work lives of Fund participants 
because many of these individuals had previous work experience in 
the construction industry before being represented by BAC. In 
additional, we believe this figure understates the number of 
participants with work lives of 45 years, because the Fund was 
established in 1972 and it was not until roughly a decade later that 
even half of BAC affiliates had commenced participation in the Fund 
(Document ID 4053, Attachment 1, p. 2).

    Similarly, The United Association of Plumbers, Fitters, Welders, 
and HVAC Service Techs, submitted that ``a review of membership records 
documented 35,649 active members who have worked 45 years or more while 
they have been a member of the union.'' They also concur with the BAC 
statement that the number may be understated given previous work 
experience (Document ID 4073, Attachment 3, p. 1). And the 
International Union of Operating Engineers' Central Pension Fund found 
the average operating engineer has over 20 years of service in the 
trade with a range up to 49.93 years (Document ID 4025, Attachment 1, 
pp. 6-7).
    Dr. Bird also objected to OSHA's approach of using a single 
representative exposure to measure lifetime exposure. He states: ``If 
exposures are variable over the course of a year, the lifetime exposure 
pattern is contrary to OSHA's assumption and the benefits from the 
proposed reduction in the PEL would be considerably less'' (Document ID 
2368, p. 19). Dr. Bird apparently faults the Agency for not considering 
the possibility that future exposures may be lower than those observed 
on a given day. However, it is equally plausible that a worker's future 
exposures may be higher than on the day they were observed by OSHA. The 
single-day exposure data is the best available data in the record for 
those workers, and the Agency does not find any persuasive evidence in 
this record to suggest an obvious bias to characterizing exposure from 
a single day rather over the course of consecutive days.
    Paragraph (i)(2)(v) of the general industry and maritime standard 
and paragraph (h)(2)(v) of the construction standard also contain 
specific provisions for diagnosing latent tuberculosis (TB) in the 
silica-exposed population and thereby reducing the risk of TB being 
spread to the population at large. OSHA currently lacks good methods 
for quantifying these benefits. Nor has the Agency attempted to assess 
benefits directly stemming from enhanced medical surveillance in terms 
of reducing the severity of symptoms from the illnesses that do result 
from present or future exposure to silica. Dr. Ruth Ruttenberg, an 
economist representing the AFL-CIO, noted this as a source of the 
underestimation of the benefits in her comments (Document ID 2256, 
Attachment 4, pp. 9-12). However, no commenters suggested how to 
quantify these effects.
    OSHA's risk estimates are based on application of exposure-response 
models derived from several individual epidemiological studies as well 
as the pooled cohort studies of Steenland et al. (2001, Document ID 
0492) and Mannetje et al. (2002, Document ID 1089). OSHA recognizes 
that there is uncertainty around any of the point estimates of risk 
derived from any single study. In its preliminary risk assessment 
(summarized in Section VI of this preamble), OSHA has made efforts to 
characterize some of the more important sources of uncertainty to the 
extent that available data permit. This specifically includes 
characterizing statistical

[[Page 16598]]

uncertainty by reporting the confidence intervals around each of the 
risk estimates (presented in the Preliminary Quantitative Risk 
Assessment, Document ID 1711); by quantitatively evaluating the impact 
of uncertainties in underlying exposure data used in the cohort 
studies; and by exploring the use of alternative exposure-response 
model forms. OSHA finds that these efforts reflect much, but not 
necessarily all, of the uncertainties associated with the approaches 
taken by investigators in their respective risk analyses. However, for 
reasons explained in Section VI of this preamble, OSHA concludes that 
characterizing the risks and benefits as a range of estimates derived 
from the full set of available studies, rather than relying on any 
single study as the basis for its estimates, better reflects the 
uncertainties in the estimates and more fairly captures the range of 
risks likely to exist across a wide range of industries and exposure 
situations.
    Section VI of this preamble provides a more complete discussion of 
the source of uncertainty in the risk assessment functions used in this 
benefits analysis. The sources of uncertainty include the degree to 
which OSHA's risk estimates reflect the risk of disease among workers 
with widely varying exposure patterns. Some workers are exposed to 
fairly high concentrations of crystalline silica only intermittently, 
while others experience more regular and constant exposure. Risk models 
employed in the quantitative assessment are based on a cumulative 
exposure metric, which is the product of average daily silica 
concentration and duration of worker exposure for a specific task. 
Consequently, these models assume the same risk for a given cumulative 
exposure regardless of the pattern of exposure, reflecting a worker's 
long-term average exposure without regard to intermittencies or other 
variances in exposure. That is, the use of the cumulative exposure 
metric in these models assumes that there are no significant dose-rate 
effects in the relationship between silica exposure and risk.
    Possible dose-rate effects in the silica exposure-response 
relationships, particularly for silicosis. OSHA's reliance on a 
cumulative exposure metric to assess the risks of respirable 
crystalline silica is discussed in Section V of this preamble. 
Uncertainty with respect to the form of the statistical models used to 
characterize the relationship between exposure level and risk of 
adverse health outcomes is discussed in Section VI.
    In its quantitative risk assessment, OSHA used the exposure-
response models from the best available evidence (i.e., the key studies 
discussed at length in Section V, Health Effects and Section VI, Final 
Quantitative Risk Assessment and Significance of Risk) to estimate 
risks for 45 years of exposure to the previous PELs, revised PEL, and 
the action level. When examining the risk estimates specifically for 
silicosis mortality and morbidity in Table VI, one interesting 
observation is the apparent difference in the exposure-response 
relationship for these two endpoints. For example, for 45 years of 
exposure to the action level (25 [mu]g/m\3\), there would be an 
estimated 4 deaths from silicosis and 21 cases of silicosis (with chest 
X-ray ILO category of 2/1 or greater) per 1,000 workers; at the 
previous PEL (100 [mu]g/m\3\), there would be an estimated 11 deaths 
from silicosis and 301 cases of silicosis per 1,000 workers. In other 
words, nearly 20 percent of silicosis cases are estimated to be fatal 
at the relatively low exposure of 25 [mu]g/m\3\ but only about 4 
percent are estimated to be fatal at the relatively high exposure of 
100 [mu]g/m\3\.\102\ Moreover, as noted previously, morbidity and 
mortality estimates change in opposite directions in response to 
varying the assumption about workers' total length of exposure. 
Although this issue was not explicitly raised in the rulemaking record, 
OSHA notes and addresses it here.
---------------------------------------------------------------------------

    \102\ Even if one subtracts off the Table VI-1 estimates of 
other silica-attributable diseases (e.g., lung cancer) from the 100 
[mu]g/m\3\ denominator, on the assumption that those diseases cause 
mortality before silicosis has a chance to do so, the ratio of fatal 
silicosis cases to the remaining silicosis diagnoses is still no 
more than 6.6 percent at 100 [mu]g/m\3\, as opposed to the ratio of 
nearly 20 percent at 25 [mu]g/m\3\.
---------------------------------------------------------------------------

    OSHA attributes this apparent difference in the exposure-response 
relationships for silicosis mortality and morbidity to several factors. 
First, the silicosis mortality study (ToxaChemica, 2004, Document ID 
0469) defined deaths using death certificate data, in which silicosis 
or unspecified pneumoconiosis was recorded as the underlying cause of 
death. In contrast, the silicosis morbidity study (Buchanan et al., 
2003, Document ID 0306) defined silicosis cases using data from chest 
x-rays showing radiographic opacities. These radiographic signs of 
silicosis represent an early endpoint that is very different from 
silicosis death as the underlying cause of death. Such disparate 
endpoints are alone one reason why OSHA does not believe that the 
exposure-response curves should necessarily be proportional.
    In addition, as discussed in Section V.E, Comments and Responses 
Concerning Surveillance Data on Silicosis Morbidity and Mortality, 
silicosis is well-known to be underreported on death certificates in 
that deaths due to silicosis could have been reported as tuberculosis 
or chronic obstructive pulmonary disease (Document ID 1089, pp. 724-
725; 1030; 3425, p. 2; 3577, Tr. 855, 867; 4204, p. 17; 2175, p. 3; 
3577, Tr. 772). Also, silica-exposed workers are at risk for other 
silica-related diseases, including lung cancer and renal disease, as 
well as other non-exposure-related causes of death such that many 
workers who contract silicosis will not ultimately die from silicosis. 
Therefore the reported silicosis deaths at any level are the lowest 
possible number of such deaths. Workers with higher cumulative 
exposures are also likely to be older, and therefore may have a higher 
rate of other conditions that could have been listed on death 
certificates. Furthermore, as discussed in Section VI, OSHA's risk 
assessment required some degree of extrapolation at high doses (e.g., 
45 years of exposure to 250 and 500 [mu]g/m\3\ respirable crystalline 
silica) that result in cumulative exposures not experienced by many of 
the cohort members studied. Thus, OSHA attributes the apparent non-
proportionality in the exposure-response curves for silicosis mortality 
and morbidity to these factors. It is possible nonetheless, that future 
research may shed additional light on this topic.
d. Estimating a Stream of Benefits Over Time
    Risk assessments in the occupational environment are generally 
designed to estimate the risk of an occupationally related illness over 
the course of an individual worker's lifetime. As previously discussed, 
the current occupational exposure profile for a particular substance 
for the current cohort of workers can be matched up against the 
expected profile after the final standard takes effect, creating a 
``steady state'' estimate of benefits. However, in order to annualize 
the benefits for the period of time after the silica rule takes effect, 
it is necessary to create a timeline of benefits for an entire active 
workforce over that period.
    There are various approaches for modeling the workforce. As 
explained below, OSHA uses a model that considers the effect of 
lowering exposures for the entire working population. At one extreme, 
however, one could assume that all of the relevant silica exposures 
will occur after the

[[Page 16599]]

standard goes into effect and none of the benefits occurs until after 
the worker retires, or at least 45 years in the future. In the case of 
lung cancer, that period would effectively be 60 years, since the 45 
years of exposure must be added to a 15-year latency period during 
which it is assumed that lung cancer does not develop.\103\ At the 
other extreme, one could assume that the benefits occur immediately, or 
at least immediately after a designated lag. Neither extreme reflects 
the reality that silica-related diseases that this standard aims to 
reduce significantly occur at various times during and after the 
working lives of these populations of workers, with the majority of 
cases occurring sometime after the typical worker is middle aged. 
Indeed, based on the various risk models (as detailed in model life 
tables in Appendix A to the QRA), which reflect real-world experience 
with development of disease over an extended period of time; it appears 
that the actual pattern occurs at some point between these two 
extremes.
---------------------------------------------------------------------------

    \103\ This assumption is consistent with the 15-year lag 
incorporated in the lung cancer risk models used in OSHA's QRA.
---------------------------------------------------------------------------

    The model OSHA uses, therefore, is one that considers the effect of 
lowering exposures for the entire working population. This population-
based approach does not simply follow the pattern of the risk 
assessments, which are based in part on life tables, and observe that 
typically the risk of the illness grows gradually over the course of a 
working life and into retirement. While this would be a good working 
model for an individual exposed over a working life, it is not very 
descriptive of the exposed population as a whole. In the latter case, 
in order to estimate the benefits of the standard over time, OSHA 
considers that workers currently being exposed to silica are going to 
vary considerably in age. Since the health risks from crystalline 
silica exposure depend on a worker's cumulative exposure over a working 
lifetime, the overall benefits of the final standard will phase in over 
several decades, as the cumulative exposure gradually falls for all age 
groups, until those now entering the workforce reach retirement and the 
annual stream of silica-related illnesses reaches a new, significantly 
lowered ``steady state.'' However, the beneficial effects of the rule 
begin in the near term and increase over time until that ``steady 
state'' is reached; and, for a given level of cumulative exposure, the 
near-term impact of the final rule will be greater for workers who are 
now middle-aged or older, compared to younger workers with similar 
current levels of cumulative exposure. This conclusion follows from the 
structure of the relative risk models used in this analysis and the 
fact that the background mortality rates for diseases such as lung 
cancer, chronic obstructive pulmonary disease and renal disease 
increase with age.
    In order to characterize the magnitude of benefits before the 
steady state is reached, OSHA created a linear phase-in model to 
reflect the potential timing of benefits. Specifically, OSHA estimated 
that, for all non-cancer cases, while the number of cases of silica-
related disease would gradually decline as a result of the final rule, 
they would not reach the steady-state level until 45 years had passed. 
The reduction in cases in any given year in the future was estimated to 
be equal to the steady-state reduction (the number of cases in the 
baseline minus the number of cases in the new steady state) times the 
ratio of the number of years since the standard was implemented and a 
working life of 45 years; in other words, the number of non-malignant 
silica-relates cases of disease avoided is assumed to increase in 
direct proportion to the number of years the standard is in effect 
until year 45, at which point the numbers hold steady. This formulation 
also assumes that the number of workers is constant over the entire 
time frame. Expressed mathematically:

Nt = (C-S) x (t/45),

where Nt is the number of non-malignant silica-related 
diseases avoided in year t; C is the current annual number of non-
malignant silica-related diseases; S is the steady-state annual number 
of non-malignant silica-related diseases; and t represents the number 
of years after the final standard takes effect, with t<=45.
    In the case of lung cancer, the function representing the decline 
in the number of cases as a result of the final rule is similar, but 
there would be a 15-year lag before any reduction in cancer cases would 
be achieved. Expressed mathematically, for lung cancer:

Lt = (Cm-Sm) x ((t-15)/45),

where 15 <=t <=60 and Lt is the number of lung cancer cases 
avoided in year t as a result of the final rule; Cm is the 
current annual number of silica-related lung cancers; and Sm 
is the steady-state annual number of silica-related lung cancers.
    This model was extended to 60 years for all the health effects 
previously discussed in order to incorporate the 15-year lag, in the 
case of lung cancer, and a 45-year working life. OSHA also has 
estimated the benefits using other job tenures. For this purpose, OSHA 
examined scenarios for the same number of years--60 years--but with the 
work force restarting exposure whenever the first job tenure cycle was 
complete.
    OSHA also has estimated the benefits using other job tenures. For 
this purpose, OSHA examined scenarios for the same number of years--60 
years--but with the work force restarting exposure whenever the first 
job tenure cycle was complete.
    In order to compare costs to benefits, OSHA assumes that economic 
conditions remain constant and that annualized costs will continue for 
the entire 60-year time horizon used for the benefits analysis (as 
discussed in Chapter V of the FEA). OSHA invited comments on this 
assumption in the PEA, for both the benefit and cost analysis. OSHA was 
particularly interested in what assumptions and time horizon should be 
used instead and why. The Agency did not receive any comments on this 
point.
2. Monetizing the Benefits
    OSHA also estimates the monetary value of health and longevity 
improvements of the type associated with the final silica rule. These 
estimates are for informational purposes only because OSHA cannot use 
benefit-cost analysis as a basis for determining the PEL for a health 
standard. The Agency's methodology for monetizing benefits is based on 
both the relevant academic literature and on the approaches OSHA and 
other regulatory agencies have taken in the past for similar regulatory 
actions.
    In explaining OSHA's methodology for monetizing health and 
longevity improvements, OSHA relied on a 45 year occupational tenure. 
Later, OSHA discusses monetization under alternative occupational 
tenures of 25, 13 and 6.6 years.
a. Placing a Monetary Value on Individual Silica-Related Fatalities 
Avoided
    To estimate the monetary value of the reductions in the number of 
silica-related fatalities, OSHA relied, as OMB recommends in its 
Circular A-4, on estimates developed from the willingness of affected 
individuals to pay to avoid a marginal increase in the risk of 
fatality. While a willingness-to-pay (WTP) approach clearly has 
theoretical merit, it should be noted that an individual's willingness 
to pay to reduce the risk of fatality would tend to underestimate the 
total willingness to pay, which would include the willingness of 
others--particularly the

[[Page 16600]]

immediate family--to pay to reduce that individual's risk of 
fatality.\104\
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    \104\ See, for example, Thaler and Rosen (1976), (Document ID 
1520, pp. 265-266); Sunstein (2004) (Document ID 1523, p. 433); or 
Viscusi, Magat and Forrest (1988), the last of whom write that 
benefits from improvement in public health ``consist of two 
components, the private valuation consumers attach to their own 
health, plus the altruistic valuation other members of society place 
on their health.'' That paper uses contingent valuation methods to 
suggest that the effect of altruism could significantly alter 
willingness-to-pay estimates for some kinds of health improvement. 
There are, however, many questions concerning how to measure the 
altruistic component and the conditions under which it might matter.
---------------------------------------------------------------------------

    For estimates using the willingness-to-pay concept, OSHA relies on 
existing studies of the imputed value of fatalities avoided based on 
the theory of compensating wage differentials in the labor market. 
These studies rely on certain critical assumptions for their estimates, 
particularly that workers understand the risks to which they are 
exposed and that workers have legitimate choices between high- and low-
risk jobs. Actual labor markets only imperfectly reflect these 
assumptions. A number of academic studies, as summarized in Viscusi and 
Aldy (2003, Document ID 1220), have shown a correlation between higher 
job risk and higher wages, suggesting that employees demand monetary 
compensation in return for a greater risk of injury or fatality. The 
estimated trade-off between lower wages and marginal reductions in 
fatal occupational risk--that is, workers' willingness to pay for 
marginal reductions in such risk--yields an imputed value of an avoided 
fatality: the willingness-to-pay amount for a reduction in risk divided 
by the reduction in risk.
    OSHA has used this approach in many recent proposed and final rules 
(see 69 FR 59305 (Oct. 4, 2004) and 71 FR 10099 (Feb. 28, 2006), the 
preambles for the proposed and final hexavalent chromium rule). 
Limitations to this approach (see Hintermann, Alberini and Markandya, 
(2010, Document ID 0739)), have been examined in a recent WTP analysis, 
by Kniesner et al. (2012, Document ID 3819), using panel data to 
examine the trade-off between fatal job risks and wages. This article 
addressed many of the earlier econometric criticisms by controlling for 
measurement error, endogeneity, and heterogeneity. Accordingly, OSHA 
views this analysis as buttressing the estimates in Viscusi and Aldy 
(2003, Document ID 1220), which the Agency is continuing to rely on for 
the FEA.\105\
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    \105\ For example, if workers are willing to pay $50 each for a 
1/100,000 reduction in the probability of dying on the job, then the 
imputed value of an avoided fatality would be $50 divided by 1/
100,000, or $5,000,000. Another way to consider this result would be 
to assume that 100,000 workers made this trade-off. On average, one 
life would be saved at a cost of $5,000,000.
---------------------------------------------------------------------------

    OSHA received several comments on the use of willingness-to-pay 
measures and estimates based on compensating wage differentials. For 
example, Peter Dorman, Professor of Economics, Evergreen State College, 
Eric Frumin of Change to Win, and Dr. Ruth Ruttenberg, representing the 
AFL-CIO, in addition to critiquing the academic studies used to develop 
the willingness-to-pay measure, cited the absence of effective labor 
markets for capturing a wage differential for hazardous work (Document 
ID 2260, Attachment 1; 2372, Attachment 1, pp. 4-15; 2256, Attachment 
4, p. 9). OSHA acknowledges that there has been an absence of a wage 
premium for risk in certain labor markets, and cites this absence in 
Chapter II of the FEA as an example of market failure. Nonetheless, 
while the Agency agrees that the absence of a wage premium for risk 
demonstrates the need for regulatory intervention in the labor market, 
it does not, in itself, invalidate the use of the willingness-to-pay 
approach for the informational purposes for which OSHA calculates 
benefits, so long as there are some reasonably well-functioning parts 
of the labor market that can be used to estimate the willingness to pay 
for some subset of workers. OSHA finds that there are such sections of 
the labor market.
    Several studies indicate that there are enough functional parts of 
the labor market to allow for some quantification of the risk, 
typically expressed as the value of a statistical life (VSL), a 
possible measure of willingness to pay. For example, Viscusi and Aldy 
(2003) conducted a meta-analysis of studies in the economics literature 
that use a willingness-to-pay methodology to estimate the imputed value 
of life-saving programs and found that each fatality avoided was valued 
at approximately $7 million in 2000 dollars. For the PEA, the Agency 
used the GDP Deflator (U.S. BEA, 2010) to convert this estimate to $8.7 
million in 2009 dollars for each fatality avoided. For the FEA, the 
base year has been further updated to 2012 using the GDP Deflator (U.S. 
BEA, 2013), yielding an estimate of $9.0 million per fatality 
avoided.\106\
---------------------------------------------------------------------------

    \106\ An alternative approach to valuing an avoided fatality is 
to monetize, for each year that a life is extended, an estimate from 
the economics literature of the value of that statistical life-year 
(VSLY). See, for instance, Aldy and Viscusi (2007) (Document ID 
1522) for discussion of VSLY theory and FDA (2003, Document ID 1618, 
pp. 41488-9), for an application of VSLY in rulemaking. OSHA has not 
investigated this approach which was not recommended by any 
commenter in the record. It acknowledges, however, that such an 
approach would have the effect of lowering estimated benefits 
because silica-related health outcomes largely affect older workers 
and retirees as they approach actuarially expected life 
expectancies.
---------------------------------------------------------------------------

    There are a number of factors that could influence the value of a 
statistical life (VSL) calculation in different labor markets, but for 
the purpose of its analysis OSHA has identified methods for normalizing 
the risk between markets. For example, in Kniesner, Viscusi, and Ziliak 
(2010, Document ID 0767), the authors addressed the issue of the 
heterogeneity of the VSL approach among various labor markets by 
developing analytical tools (quantile regressions) for differentiating 
by income. For the purpose of quantifying the effects of income growth 
over time on the value of a statistical life, OSHA relies on their 
data, which generally show that VSL increases with increased worker 
income (as banded by quartile). Despite potential weaknesses in the VSL 
approach, Executive Order 12866 recommends monetization of regulatory 
benefits (including increases in longevity), and the Agency concludes 
this constitutes the best available method for this purpose.
b. Placing a Monetary Value on Individual Non-Fatal Silica-Related 
Diseases Avoided
    In addition to the benefits that are based on the imputed value of 
fatalities avoided, workers also place a value on occupational injuries 
or illnesses avoided, which reflect their willingness to pay to avoid 
monetary costs (for medical expenses and lost wages) and quality-of-
life losses as a result of occupational illness. Silicosis, lung 
cancer, and renal disease can be totally disabling and adversely affect 
individuals for years or even decades in non-fatal cases, or before 
ultimately proving fatal. Because monetary measures of the willingness 
to pay for avoiding these illnesses are rare and difficult to find OSHA 
has included a range based on a variety of estimation methods.
    Consistent with Buchanan et al. (2003), OSHA estimated the total 
number of moderate to severe silicosis cases prevented by the final 
rule, as measured by 2/1 or more severe x-rays (based on the ILO rating 
system). However, while radiological evidence of moderate to severe 
silicosis is evidence of significant material impairment of health, 
placing a precise monetary value on this condition is difficult, in 
part because the severity of symptoms may vary significantly among 
individuals.

[[Page 16601]]

For that reason, in the PEA, as well as in the FEA, the Agency has 
employed a broad range of valuation, which should encompass the range 
of severity these individuals may encounter. Using the willingness-to-
pay approach, discussed in the context of the imputed value of 
fatalities avoided, OSHA has estimated a range in valuations (updated 
and reported in 2012 dollars) that runs from approximately $64,000 per 
case--which reflects estimates developed by Viscusi and Aldy (2003, 
Document ID 1220), based on a series of studies primarily describing 
simple accidents--to upwards of $5.2 million per case--which reflects 
estimates developed by Magat, Viscusi, and Huber (1996, Document ID 
0791) for non-fatal cancer. The latter number is based on an approach 
that applies a willingness-to-pay value to avoid serious illness that 
is calibrated relative to the value of an avoided fatality. OSHA (2006, 
Document ID 0941) previously used this approach in the FEA supporting 
its hexavalent chromium final rule, and EPA (2003, Document ID 0657) 
used this approach in its Stage 2 Disinfection and Disinfection 
Byproducts Rule concerning regulation of primary drinking water. EPA 
used the study by Magat, Viscusi & Huber (1996, Document ID 0791) on 
the willingness to pay to avoid nonfatal lymphoma and chronic 
bronchitis as a basis for valuing a case of nonfatal cancer at 58.3 
percent of the value of a fatal cancer. OSHA's estimate of $5.2 million 
in 2012 dollars for an avoided case of non-fatal cancer is based on 
this 58.3 percent figure.
    There are several benchmarks for valuation of health impairment due 
to silica exposure, using a variety of techniques, which provide a 
number of mid-range estimates between OSHA's high and low estimates of 
$5.2 million and $64,000. For example, EPA (2008) recently estimated a 
cost of approximately $460,000, in 2008 dollars, per case of chronic 
bronchitis, which OSHA (2009) used as the basis for comparison with 
less severe lung impairments from diacetyl exposure. Another approach 
is to employ a cost-of-injury model. Combining estimates of 
productivity losses (i.e., lost wages, fringe benefits, and household 
production), medical costs (including hospitalizations), and loss of 
quality-of-life components, Miller (2005), using an enhanced cost-of-
injury model, estimated the average silicosis disease cost the 
equivalent of $335,000 in 2012 dollars).\107\
---------------------------------------------------------------------------

    \107\ Miller (2005) estimated the cost of a silicosis case, 
using an enhanced direct cost approach--including a quality-
adjusted-life-years component--to be $265,808 in 2002 dollars.
---------------------------------------------------------------------------

    Miller (2005) also estimated the morbidity costs of several 
different pneumoconioses other than silicosis and found the other cases 
to be even more costly to society than silicosis. While the full costs 
of renal disease are less well known, the medical costs alone of 
dealing with end-stage renal disease run over $64,000 annually per 
patient (Winkelmayer, 2002). This suggests that a more comprehensive 
analysis of the direct costs of renal disease, as well as for the 
various lung impairments, would produce an estimate well above the 
$64,000 estimate of injuries in Viscusi and Aldy (2003). Moreover, 
several studies (e.g., Alberini and Krupnick, 2000) have found that the 
cost of injury approach tends to significantly underestimate the true 
economic cost of an injury or illness, relative to the willingness to 
pay approach, which includes quality of life impacts and psychic costs 
as well as medical costs and lost income. In this way, looking only at 
specific elements of this valuation, such as a workers compensation 
payouts (to the extent they can be linked to a specific employer in a 
timely manner), would dramatically underestimate the cost of the 
illness to society.
    Thus, the various studies presented in Chapter VII of the FEA 
suggest that the imputed value of avoided morbidity associated with 
silica exposure, both for cases preceding death and for non-fatal 
cases, ranges between $64,000 and $5.2 million, depending in part on 
the model used to compute the value and in part on the severity and 
duration of the case. OSHA considers this wide range of estimates is 
descriptive of the value of preventing morbidity associated with 
moderate-to-severe silicosis, as well as the morbidity preceding 
mortality due to other causes enumerated here--lung cancer, lung 
diseases other than cancer, and renal disease. OSHA is therefore 
applying these values to monetize cases of avoided silica-related 
morbidity.\108\ OSHA has included these estimates of silicosis 
morbidity throughout the analysis. For mortality, OSHA has included the 
midpoints of $64,000 and $5.2 million ($2.63 million) for all mortality 
cases. The high and low estimates in the remainder of this document for 
mortality not only reflect different point estimates, but different 
levels for the morbidity effect.
---------------------------------------------------------------------------

    \108\ For the purpose of simplifying the estimation of the 
monetized benefits of avoided illness and death, OSHA simply added 
the monetized benefits of morbidity preceding mortality to the 
monetized benefits of mortality at the time of death, and both would 
be discounted at that point. In theory, however, the monetized 
benefits of morbidity should be recognized (and discounted) at the 
onset of morbidity, as this is what a worker's willingness to pay is 
presumed to measure--that is, the risk of immediate death or an 
immediate period of illness that a worker is willing to pay to 
avoid--a practice that would increase the present value of 
discounted morbidity benefits. A parallel tendency toward 
underestimation occurs with regard to morbidity not preceding 
mortality, since it implicitly assumes that the benefits occur at 
retirement, as per the Buchanan model, but many, if not most, of the 
2/0 or higher silicosis cases will have begun years before (with 
those classifications, in turn, preceded by a 1/0 classification). 
As a practical matter, however, the Agency lacks sufficient data at 
this time to refine the analysis in this way.
---------------------------------------------------------------------------

Public Comment on Valuing Non-Fatal Cases of Silicosis
    OSHA requested public input on the issue of valuing the cost to 
society of non-fatal cases of moderate-to-severe silicosis, as well as 
the morbidity associated with other related diseases of the lung, and 
with renal disease. A number of commenters did not directly provide 
quantitative estimates of the cost of silicosis or other silica-related 
health effects, but provided qualitative descriptions of the heavy 
burden to health, work, and family life incurred by having silicosis.
    For example, Alan White, of the United Steelworkers Local Union 
593, who developed silicosis after working in a foundry for 16 years as 
a general helper, described the practical implications of developing 
silicosis:

    First of all, for me, there was the growing problem of being out 
of breath sooner than I used to. That's a difficult situation for a 
competitor, especially since I didn't know why. Then, I received a 
big surprise during the conversation with the first doctor when I 
found out that I have silicosis and that I will lose my job. He and 
the other doctors all agreed that the diagnosis is silicosis. 
Watching your wife and other loved ones cry as they figure out what 
silicosis is was a big hit and then, shortly afterward, there was 
the radical pay cut from a transfer out of the foundry to a 
department where I knew nothing because I chose my health over money 
. . . There are also difficulties outside of work and issues for me 
to look forward to in the future. Walking while talking on a cell 
phone is very exhaustive, as well as walking up the stairs from my 
basement to my second floor apartment. I have increasing difficulty 
on my current job. Certain irritants like air fresheners, potpourri 
and cleaners make home life increasingly difficult and I was told 
that it's downhill from here for both work and home life (Document 
ID 3477, p. 2).

    Mr. White also described how the foundry went to considerable 
expense to hire people to do the job he previously had done, including 
the costs to the foundry for mistakes made by the trainees replacing 
him. Such personnel costs to the employer would not be

[[Page 16602]]

captured by either the willingness-to-pay approach or cost-of-injury 
approach.
    In addition to questioning the underlying willingness to pay 
approach, at least one commenter indicated various ways in which the 
approach employed by OSHA would tend to underestimate the economic 
benefits of the rulemaking. Dr. Ruttenberg argued that the WTP approach 
does not include costs to third parties of silica-related illnesses and 
injuries, starting with a number of government programs:

    In its Preliminary Economic Analysis, OSHA says that it wants 
public input on the issue of valuing the cost to society of non-
fatal cases of moderate-to severe silicosis, as well as the 
morbidity associated with other related diseases of the lung, and 
with renal disease. (PEA, p. VII-15) This is a key request because 
adding such societal costs can double the benefits of preventing 
these diseases. In an article by a lawyer and two economists looking 
at the social cost of dangerous products, Shapiro, Ruttenberg, and 
Leigh argue that a large economic burden is borne by private 
insurance, government programs, the business community and the 
victims and their families. Those affected by occupational 
exposures, such as silica, may become eligible for a range of cash 
or in-kind assistance. Such programs may include unemployment 
compensation, food stamps, Medicaid, Medicare, State Children's 
Health Insurance Program (SCHIP), Temporary Assistance for Needy 
Families (TANF), Social Security Disability, and Old Age, Survivors 
and Disability Insurance. There are also costs for use of military 
hospitals and clinics (Document ID 2256, Attachment 4, pp. 9-10) 
(citations omitted).

    Part of the cost of the injury or fatality may be borne in 
substantial part by the victim's family:

    There is another group of costs that can easily double, or even 
triple, the direct and indirect totals. These are social and 
economic impacts that are also caused by an incident. They often 
involve third-party payments, or stress on the victim or his/her 
family members. The financial pressures on a family can include the 
need for a caregiver, need for additional income from children or 
spouse to fill the gap between previous earnings and workers 
compensation, or psychotherapy for family members to cope with harsh 
new realities. When children lose their chance at college and higher 
future earnings, the impact can be hundreds of thousands of dollars 
(Document ID 2256, Attachment 4).

    Dr. Ruttenberg pointed to an existing Department of Transportation 
study, which suggested that only a fraction of the economic cost of 
motor vehicle accidents was actually borne by the victim, with the 
remainder of the costs split between governmental bodies, insurers, and 
other parties (Document ID 2256, Attachment 4, p. 11).\109\
---------------------------------------------------------------------------

    \109\ The Agency acknowledges this is a likely and potentially 
substantial source of underestimation of morbidity costs and is 
currently investigating ways to capture this currently unquantified 
dimension of benefits for potential use in future rulemakings.
---------------------------------------------------------------------------

    The Center for Progressive Reform argued that there is value to 
reducing economic inequities created by occupational illnesses related 
to silica exposure:

    The proposal's implications for fair treatment of workers also 
deserve more attention. The proposed standards would benefit a 
population comprising mostly construction workers (more than 85% of 
the total affected population). This is an industry that is a 
bastion for middle class workers and those striving to attain middle 
class status. It is also an industry that employs a significant 
number of foreign-born and non-union workers, groups who typically 
have limited power to negotiate improved working conditions. 
Ensuring that these workers' health is better protected against the 
hazards of silica exposure is an important step toward reducing 
socioeconomic inequality, given the linkages between individual 
health and social mobility. Other federal agencies, including the 
National Highway Traffic Safety Administration (NHTSA) and 
Department of Justice (DOJ), have gone so far as to argue that 
equity and other non-monetizable benefits are sufficient to justify 
rules for which the monetized costs far outweigh the monetized 
benefits. (As with the OSH Act, the authorizing statutes under which 
NHTSA and DOJ were acting do not require cost-benefit analysis, much 
less require the agencies to produce rules with monetized benefits 
that outweigh monetized costs) (Document ID 2351, p. 7) (citations 
omitted).

    The Agency recognizes that, as with third party effects, there are 
aspects of economic equity issues related to occupational injury, 
illness, and mortality that merit attention for policy making. As noted 
previously, however, the OSH Act requires that OSHA policy for toxic 
substances be ultimately determined by issues of risk and feasibility, 
as opposed to cost-benefit criteria.
    The Agency requested public input on the issue of valuing the cost 
to society of non-fatal cases of moderate to severe silicosis, as well 
as the morbidity associated with other related diseases of the lung, 
and with renal disease. The final benefits analysis summarized below 
and discussed in greater detail in the FEA incorporates OSHA's response 
to public comment.
c. Adjusting Monetized Benefits To Reflect Rising Future Value
    In the PEA, OSHA suggested, provided estimates, and requested 
comment on adjusting future values of illness and mortality prevention 
to account for changes in real income over time. Ronald White of the 
Center for Effective Government favored integrating this element into 
the monetized benefits analysis (Document ID 2341, p. 3).\110\ No 
commenters argued against it. For the reasons provided in the PEA and 
described below, the Agency is adopting this approach and has used it 
to develop its primary benefits estimates.
---------------------------------------------------------------------------

    \110\ The estimates of monetized benefits to reflect changes in 
real income over time developed in the PEA contained an error in the 
formulas (an inconsistent discount rate was used) that resulted in 
underestimated benefits. That error has been corrected in the 
estimates presented in the FEA.
---------------------------------------------------------------------------

    OSHA's estimates of the monetized benefits of the final rule are 
based on the imputed value of each avoided fatality and each avoided 
silica-related disease. As previously discussed, these, in turn, are 
derived from a worker's willingness-to-pay to avoid a fatality (with an 
imputed value per fatality avoided of $9.0 million in 2012 dollars) and 
to avoid a silica-related disease (with an imputed value per disease 
avoided of between $64,000 and $5.3 million in 2012 dollars). Two 
related factors suggest that these values will tend to increase over 
time and help to better identify the amount that a worker would be 
willing to pay to avoid a fatality.
    First, economic theory and empirical evidence from the relevant 
studies indicate that the value of reducing life-threatening and 
health-threatening risks--and correspondingly the willingness of 
individuals to pay to reduce these risks--will increase as real per 
capita income increases.\111\ With increased income, an individual's 
health and life becomes more valuable relative to other goods because, 
unlike other goods, they are without close substitutes. Expressed 
differently, as income increases, consumption will increase but the 
marginal utility of consumption will decrease. In contrast, added years 
of life (in good health) are, in the model of Hall and Jones (2007, 
Document ID 0720), not subject to the same type of diminishing returns 
and, indeed, may be viewed as the ultimate good.
---------------------------------------------------------------------------

    \111\ Simple modeling can show this directly. For example, Rosen 
(1988) (Document ID 1165) demonstrates that the value of life can be 
expressed as the marginal rate of substitution between wealth and 
the probability of survival. An increase in wealth or income will 
therefore increase an individual's willingness to pay.
---------------------------------------------------------------------------

    Second, real per capita income has broadly been increasing 
throughout U.S. history, including during recent

[[Page 16603]]

periods.\112\ For example, for the period 1950 through 2000, real per 
capita income grew at an average rate of 2.31 percent a year (Hall and 
Jones, 2007, Document ID 0720),\113\ although real per capita income 
for the recent 25 year period 1983 through 2008 grew at an average rate 
of only 1.3 percent a year (U.S. Census Bureau, 2010, Document ID 
1621). More important is the fact that real U.S. per capita income is 
estimated to grow significantly in future years. The Annual Energy 
Outlook (AEO) estimates, prepared by the Energy Information 
Administration (EIA) in the Department of Energy (DOE), estimates an 
average annual growth rate of per capita income in the United States of 
2.7 percent for the period 2011-2035.\114\ The U.S. Environmental 
Protection Agency prepared its economic analysis of the Clean Air Act 
using the AEO estimates. OSHA concludes that it is reasonable to use 
the same AEO estimates employed by DOE and EPA, and correspondingly 
estimates that per capita income in the United States will increase by 
2.7 percent per year over the 60-year period in the analysis for this 
silica rule. OSHA, as discussed below, will not use this value combined 
with the best estimate of income elasticity. Instead OSHA derives a 
lower combined measure of the adjustment that combines income 
elasticity and rate of economic growth. Further, OSHA analyzes the 
sensitivity of the results to this assumption later in this chapter.
---------------------------------------------------------------------------

    \112\ In addition, as Costa (1998) and Costa and Kahn (2004) 
(Document ID 0609) point out, elderly health, longevity, and well-
being in the United States have historically been improving, which 
also has the effect of increasing the imputed value of life. Of 
course, improvements in elderly health, longevity, and well-being 
are not independent of increases in per capita income over the same 
period.
    \113\ The results are similar if the historical period includes 
a major economic downturn (such as the United States has recently 
experienced). From 1929 through 2003, a period in U.S. history that 
includes the Great Depression, real per capita income still grew at 
an average rate of 2.22 percent a year (Gomme and Rupert, 2004) 
(Document ID 0710).
    \114\ The EIA used DOE's National Energy Modeling System (NEMS) 
to produce the Annual Energy Outlook (AEO) estimates (EIA, 2011) 
(Document ID 1573). Future per capita GDP was calculated by dividing 
the projected real gross domestic product each year by the estimates 
U.S. population for that year.
---------------------------------------------------------------------------

    On the basis of the predicted increase in real per capita income in 
the United States over time and the expected resulting increase in the 
value of avoided fatalities and diseases, OSHA has adjusted its 
estimates of the benefits of the final rule to reflect the anticipated 
increase in their value over time. This type of adjustment has been 
supported by EPA's Science Advisory Board (EPA, 2000b, Document ID 
0652) \115\ and applied by EPA.\116\ OSHA accomplished this adjustment 
by modifying benefits in year i from [Bi] to [Bi 
* (1 + k)i], where ``k'' is the estimated annual increase in 
the magnitude of the benefits of the final rule.\117\
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    \115\ Supplementary evidence in support for this type of 
adjustment comes from EPA (2010) (Document ID 1713) and U.S. 
Department of Transportation (2014) guidelines.
    \116\ See, for example, EPA (2003) (Document ID 0657) and EPA 
(2008) (Document ID 0661).
    \117\ This precise methodology was suggested in Ashford and 
Caldart (1996) (Document ID 0538).
---------------------------------------------------------------------------

    What remains is to estimate a value for ``k'' with which to 
increase benefits annually in response to annual increases in real per 
capita income, where ``k'' is equal to (1 + g) * ([eta]), ``g'' is the 
expected annual percentage increase in real per capita income, and 
``[eta]'' is the income elasticity of the value of a statistical life. 
Probably the most direct evidence of the value of ``k'' comes from the 
work of Costa and Kahn (2003, 2004). They estimate repeated labor 
market compensating wage differentials from cross-sectional hedonic 
regressions using census and fatality data from the Bureau of Labor 
Statistics for 1940, 1950, 1960, 1970, and 1980. In addition, with the 
imputed income elasticity of the value of life on per capita GNP of 1.7 
derived from the 1940-1980 data, they then predict the value of an 
avoided fatality in 1900, 1920, and 2000. Given the change in the value 
of an avoided fatality over time, it is possible to estimate a value of 
``k'' of 3.4 percent a year from 1900-2000; of 4.3 percent a year from 
1940-1980; and of 2.5 percent a year from 1980-2000.\118\
---------------------------------------------------------------------------

    \118\ These estimates for ``k'' were not reported in Costa and 
Kahn (2003 Document ID 0610, 2004, Document ID 0609) but were 
derived by OSHA from the data presented. The changes in the value of 
``k'' for the different time periods mainly reflect different growth 
rates of per capita income during those periods.
---------------------------------------------------------------------------

    Other, more indirect evidence comes from estimates in the economics 
literature on the income elasticity of the value of a statistical life. 
Viscusi and Aldy (2003, Document ID 1220) performed a meta-analysis on 
49 wage-risk studies and concluded that the confidence interval upper 
bound on the income elasticity did not exceed 1.0 and that the point 
estimates across a variety of model specifications ranged between 0.5 
and 0.6.\119\ Applied to a long-term increase in per capita income of 
about 2.7 percent a year, this would suggest a value of ``k'' of about 
1.5 percent a year.
---------------------------------------------------------------------------

    \119\ These results conflict with the more recent work by Hall 
and Jones (2007) (Document ID 0720), which concludes that the income 
elasticity of the value of life should be larger than 1.
---------------------------------------------------------------------------

    More recently, Kniesner, Viscusi, and Ziliak (2010, Document ID 
0767), using panel data quintile regressions, developed an estimate of 
the overall income elasticity of the value of a statistical life of 
1.44. Applied to a long-term increase in per capita income of about 2.7 
percent a year, this would suggest a value of ``k'' of about 3.9 
percent a year.
    Based on the preceding discussion of these three approaches for 
estimating the annual increase in the value of the benefits of the 
final rule and the fact that the estimated increase in real per capita 
income in the United States has flattened in recent years and could 
remain so, OSHA has selected a conservative value for ``k'' of 
approximately 2 percent a year over the next 60 years.
    Thus, based on the best current thinking and data on willingness to 
pay and its relationship to income elasticity as income increases, OSHA 
concludes that a 2 percent increase in benefits per year, as measured 
by a corresponding anticipated increase in VSL, is a reasonable, mid-
range estimate. However, OSHA recognizes the uncertainties surrounding 
these estimates and has subjected them to sensitivity analysis, as 
discussed below.
    Accordingly, OSHA concludes that the rising value, over time, of 
health benefits is a real phenomenon that should be taken into account 
in estimating the annualized benefits of the final rule. Table VII-4, 
in the following section, and the monetized benefits estimates that 
follow it, show estimates of the monetized benefits of the silica rule 
with this adjustment integrated into the valuation. OSHA provides a 
sensitivity analysis of the effects of this approach later in this 
chapter.
d. The Monetized Benefits of the Final Rule
    Table VII-27 presents the estimated annualized (over 60 years, 
using a 0 percent discount rate) benefits from each of these components 
of the valuation, and the range of estimates, based on risk model 
uncertainty (notably in the case of lung cancer), and the range of 
uncertainty regarding valuation of morbidity. As shown, the full range 
of monetized benefits, undiscounted, for the final PEL of 50 [micro]g/
m\3\ runs from $7.3 billion annually, in the case of the lowest 
estimate of lung cancer risk and the lowest valuation for morbidity, up 
to $19.3 billion annually, for the highest of both. Note that the value 
of total benefits is more sensitive to the valuation of morbidity 
(ranging from $7.9 billion to $18.5 billion, given estimates at the 
midpoint of the lung cancer models) than to the lung cancer model used 
(ranging from $12.5 to $13.8

[[Page 16604]]

billion, given estimates at the midpoint of the morbidity 
valuation).\120\
---------------------------------------------------------------------------

    \120\ As previously indicated, these valuations include all the 
various estimated health endpoints. In the case of mortality this 
includes lung cancer, non-malignant respiratory disease and end-
stage renal disease. The Agency highlighted lung cancers in this 
discussion due to the model uncertainty. In calculating the 
monetized benefits, the Agency is typically referring to the 
midpoint of the high and low ends of potential valuation--in this 
case, the undiscounted midpoint of $7.7 billion and $19.5 billion.
---------------------------------------------------------------------------

    This result comports with the very wide range of valuation for 
morbidity. At the low end of the valuation range, the total value of 
benefits is dominated by mortality ($7.7 billion out of $7.9 billion at 
the case frequency midpoint), whereas at the high end the majority of 
the benefits are related to morbidity ($11.2 billion out of $18.7 
billion at the case frequency midpoint). Also, the analysis illustrates 
that most of the morbidity benefits are related to silicosis cases that 
are not ultimately fatal. At the valuation and case frequency midpoint 
of $13.3 billion, $7.7 billion in benefits are related to mortality, 
$2.0 billion are related to morbidity preceding mortality, and $3.5 
billion are related to morbidity not preceding mortality.
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BILLING CODE 4510-26-C
3. Discounting of Monetized Benefits
    As previously noted, the estimated stream of benefits arising from 
the final silica rule is not constant from year to year, both because 
of the 45-year delay after the rule takes effect until all active 
workers obtain reduced silica exposure over their entire working lives 
and because of, in the case of lung cancer, a 15-year latency period 
between reduced exposure and a reduction in the probability of disease. 
An appropriate discount rate \121\ is needed to reflect the timing of 
benefits over the 60-year period after the rule takes effect and to

[[Page 16606]]

allow conversion to an equivalent steady stream of annualized 
benefits.\122\
---------------------------------------------------------------------------

    \121\ Here and elsewhere throughout this section, unless 
otherwise noted, the term ``discount rate'' always refers to the 
real discount rate--that is, the discount rate net of any 
inflationary effects.
    \122\ This essential point was missed in a comment by Dr. 
Ruttenberg, which claimed that OSHA's estimates of the benefits of 
an avoided fatality were forty percent below the VSL estimate of 
$8.7 million (in 2009 dollars) that the Agency was using (Document 
ID 2256, Attachment 4, p. 9). The difference is due to the fact that 
the avoided fatalities occurred over a 60 year period and had to be 
discounted.
---------------------------------------------------------------------------

a. Alternative Discount Rates for Annualizing Benefits
    Following OMB (2003) guidelines (Document ID 1493], OSHA has 
estimated the annualized benefits of the final rule using separate 
discount rates of 3 percent and 7 percent. Consistent with the Agency's 
own practices in recent final and final rules, OSHA has also estimated, 
for benchmarking purposes, undiscounted benefits--that is, benefits 
using a zero percent discount rate.
    The ``appropriate'' or ``preferred'' discount rate to use to 
monetize health benefits is a controversial topic, which has been the 
source of scholarly economic debate for several decades.\123\ However, 
in simplest terms, the basic choices involve a social opportunity cost 
of capital approach or social rate of time preference approach. OSHA 
analyzes the benefits of this rule under both approaches.
---------------------------------------------------------------------------

    \123\ For a more detailed discussion of the major issues, see, 
for example, Lind (1982a, 1982b, and 1990, Document ID1622); EPA 
(2000a, Document ID 1327, Chapter 6); and OMB (2003, Document ID 
1493, pp. 31-37).
---------------------------------------------------------------------------

    The social opportunity cost of capital approach reflects the fact 
that private funds spent to comply with government regulations have an 
opportunity cost in terms of foregone private investments that could 
otherwise have been made. The relevant discount rate in this case is 
the pre-tax rate of return on the foregone investments (Lind, 1982b, 
pp. 24-32) (Document ID 1622).
    The rate of time preference approach is intended to measure the 
tradeoff between current consumption and future consumption, or in the 
context of the final rule, between current benefits and future 
benefits. The individual rate of time preference is influenced by 
uncertainty about the availability of the benefits at a future date and 
whether the individual will be alive to enjoy the delayed benefits. By 
comparison, the social rate of time preference takes a broader view 
over a longer time horizon--ignoring individual mortality and the 
riskiness of individual investments (which can be accounted for 
separately).\124\
---------------------------------------------------------------------------

    \124\ It is not always possible to explicitly model all forms of 
uncertainty that are relevant to a regulatory cost-benefit analysis 
(e.g., medical innovations that allow for more successful treatment 
of illnesses or changes in industrial practices or locations that in 
turn change the exposure profile of workers subject to a 
regulation). Because these uncertainties tend to increase as the 
time horizon being analyzed lengthens, application of a discount 
rate provides a reduced-form approach to less heavily weighting the 
least-certain estimated benefits and costs.
---------------------------------------------------------------------------

    A usual method for estimating the social rate of time preference is 
to calculate the post-tax real rate of return on long-term, risk-free 
assets, such as U.S. Treasury securities (OMB, 2003, Document ID 1493). 
A variety of studies have estimated these rates of return over time and 
reported them to be in the range of approximately 1-4 percent.
    OMB Circular A-4 (2003) recommends using discount rates of 3 
percent (representing the social rate of time preference) and 7 percent 
(a rate estimated using the social cost of capital approach) to 
estimate benefits and net benefits (Document ID 1493). Ronald White of 
the Center for Effective Government endorsed the use of a 3 percent 
discount rate--since it ``appropriately reflects a social rate of time 
preference approach consistent with recommendations for benefits 
evaluation by the U.S. Environmental Protection Agency'' (Document ID 
2341, pp. 3-4). Charles Gordon argued for a 0 percent discount rate:

    The economic literature indicates that the social discount rate 
should be 2 percent or 3 percent. But I believe the social discount 
rate should be zero, because if you were asked the question, do you 
want yourself saved from crystalline silica exposure . . . or do you 
want your son to be saved from crystalline silica death 20 years 
from now, you could not answer that question. You could not give a 
preference (Document ID 3588, Tr. 3789-90).

    In acknowledgement of OMB Circular A-4 (2003, Document ID 1493), 
OSHA presents benefits and net benefits estimates using discount rates 
of 3 percent (representing the social rate of time preference) and 7 
percent (a rate estimated using the social cost of capital approach). 
The weight of the evidence favors using a discount rate of 3 percent or 
less, and that 3 percent is one of the options permitted by OMB, the 
Agency is using a 3 percent discount rate to display its primary 
estimates of benefits under the social rate of time preference method.
b. Summary of Annualized Benefits Under Alternative Discount Rates
    Table VII-28a through Table VII-28d presents OSHA's estimates of 
the sum of the annualized benefits of the final rule, under various 
occupational tenure assumptions, using alternative discount rates of 0, 
3, and 7 percent, with a breakout between construction and general 
industry/maritime, with each table presenting these results for a 
different tenure level. All of these benefits calculations reflect 
willingness-to-pay values that, as previously discussed, increase in 
real value at 2 percent a year.
    Given that the stream of benefits extends out 60 years, the value 
of future benefits is highly sensitive to the choice of discount rate. 
As previously established in Table VII-27, the undiscounted benefits 
(i.e., using the 0 percent discount rate) for the scenario in which 
workers are uniformly exposed to silica for 45 years range from $7.3 
billion to $19.3 billion annually. In Table VII-28a, for 45 years 
tenure, using a 3 percent discount rate, the annualized benefits range 
from $4.8 billion to $12.6 billion. Using a 7 percent discount rate, 
the annualized benefits range from $2.7 billion to $6.9 billion. As can 
be seen, going from undiscounted benefits (with a midpoint of $13.3 
billion) to benefits calculated at a 7 percent discount rate (with a 
midpoint of $4.8 billion) has the effect of cutting the annualized 
benefits of the final rule by 64 percent.
    Comparing across tenure levels for representative benefits, Table 
VII-28a for 45 years tenure has total benefits at the midpoint estimate 
of $8.7 billion at a 3 percent discount rate and $4.8 billion at 7 
percent discount rate. Table VII-28b for 25 years tenure has total 
benefits at the midpoint estimate of $10.0 billion at a 3 percent 
discount rate and $5.5 billion at 7 percent discount rate. Table VII-
28c for 13 years tenure has total benefits at the midpoint estimate of 
$12.3 billion at a 3 percent discount rate and $6.8 billion at 7 
percent discount rate. Finally, Table VII-28d for 6.6 years tenure has 
total benefits at the midpoint estimate of $16.1 billion at a 3 percent 
discount rate and $9.0 billion at 7 percent discount rate.
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[[Page 16611]]


BILLING CODE 4510-26-C
4. Estimates of Net Benefits of the Final Rule
    OSHA has estimated as shown in Table VII-29, the monetized and 
annualized net benefits of the final rule (with a PEL of 50 [micro]g/
m\3\ in general industry/maritime and construction and Table 1 
governing almost all controls in Construction), based on the benefits 
model and costs previously presented in this chapter and in Chapter V 
of the FEA. Net benefits are the difference between benefits and costs.
    Table VII-29 shows net benefits using alternative discount rates of 
0, 3, and 7 percent for benefits and costs, including the previously 
discussed adjustment to monetized benefits to reflect increases in real 
per capita income over time.
    As previously noted, the OSH Act requires the Agency to set 
standards based on eliminating significant risk to the extent feasible. 
An alternative criterion of maximizing net (monetized) benefits may 
result in very different regulatory outcomes. Thus, this analysis of 
estimated net benefits has not been used by OSHA as the basis for its 
decision concerning the choice of a PEL or of ancillary requirements 
for the final silica rule. Instead, it is provided pursuant to 
Executive Orders 12866 and 13563. OSHA has used the 45 year 
occupational tenure in its main analysis. OSHA has also examined other 
possible tenures and provided the results. The occupational tenure 
results are such the benefits are higher the shorter the occupational 
tenure. Examination of shorter tenure would actually increase the net 
benefits because more workers are exposed to silica, albeit for a 
shorter time each.
    Table VII-29 also shows results of estimates of annualized net 
benefits for an alternative PEL of 100 [micro]g/m\3\. Under this 
regulatory alternative, the PEL would be changed from 50 [micro]g/m\3\ 
to 100 [micro]g/m\3\ for all industries covered by the final rule, and 
the action level would be changed from 25 [micro]g/m\3\ to 50 [micro]g/
m\3\ (thereby keeping the action level at one-half of the PEL). The 
ancillary provisions of the standard, such as the medical surveillance 
provisions, would remain the same in this alternative as in this final 
rule, but would be impacted by factors such as changes in respirator 
use and effects on other provisions such as medical surveillance. For 
example, in the construction sector where medical surveillance 
requirements are triggered by respirator use, a reduction in respirator 
use would result in a decrease in the costs associated with medical 
surveillance. Under this alternative, OSHA determined in the PEA that 
Table 1 requirements for respirator use would be eliminated and that 
only abrasive blasters and some underground construction workers, which 
are not included in Table 1, would be required to wear respirators. 
However, the number of mortalities and morbidities would rise if 
workers were exposed to higher levels of silica. OSHA did not receive 
comment on its analysis of this alternative.
    As previously noted in this summary, the choice of discount rate 
for annualizing benefits has a significant effect on annualized 
benefits. The same is true for net benefits. For example, the net 
benefits using a 7 percent discount rate for benefits are considerably 
smaller than the net benefits using a 0 percent discount rate, 
declining by more than half to two-thirds under all scenarios. 
(Conversely, as noted in Chapter V of the FEA, the choice of discount 
rate for annualizing costs has only a very minor effect on annualized 
costs.)

[[Page 16612]]

[GRAPHIC] [TIFF OMITTED] TR25MR16.106

    The estimates of net benefits in Table VII-29 show that:
     While the net benefits of the final rule vary 
considerably--depending on the choice of discount rate used to 
annualize benefits and on whether the calculated benefits are in the 
high, midpoint, or low range--benefits exceed costs for the 50 [mu]g/
m\3\ PEL in all scenarios that OSHA considered (i.e., the highest 
estimate for costs is lower than the lowest estimate for benefits).
     The Agency's best estimate of the net annualized benefits 
of the final rule--using a uniform discount rate for both benefits and 
costs of 3 percent--and cognizant of the uncertainties inherent in the 
analysis, is between $3.8 billion and $11.6 billion, with a midpoint 
value of $7.7 billion.

[[Page 16613]]

     The alternative of a 100 [mu]g/m\3\ PEL has lower net 
benefits under all assumptions, relative to the 50 [mu]g/m\3\ PEL. 
However, for this alternative PEL, benefits were also found to exceed 
costs in all scenarios that OSHA considered.
    One commenter, the Mercatus Institute, argued that the benefits for 
the proposed rule were overestimated due to OSHA's assumption of full 
compliance, and that this simultaneously underestimated costs, since 
the cost of complying with existing rules is assumed away. This 
commenter stated that the Agency should not assume that firms will 
necessarily comply with the Agency's rules and the benefits estimates 
should therefore be lower (Document ID 1819, p. 9). OSHA makes three 
points in response. First, the argument is logically inconsistent--if 
the Agency did not assume full compliance with the previous PELs and 
assumes compliance with the new PEL, as Mercatus advocates, it is true 
that the estimated costs would increase, but so would the estimated 
benefits. Second, the logic for the Mercatus Institute's argument seems 
to be undercut by the Mercatus Institute's own observation that the 
Agency has had success in reducing silicosis, which suggests that in 
the long run, at least, firms actually do comply with OSHA rules 
(Document ID 1819, pp. 4-5). Finally, as discussed in the engineering 
controls section of Chapter V of the FEA, the Agency has determined 
that the best way for it to calculate costs and benefits is to estimate 
the incremental costs and benefits of the standard by assuming full 
compliance. OSHA also emphasizes that the compliance assumption applies 
to both costs and benefits so that the comparison of one to the other 
is not necessarily unduly weighted in either direction (an exception 
would be the counterfactual scenario in which extremely high non-
compliance by a few employers changed benefits estimates substantially 
but cost estimates only slightly).\125\
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    \125\ If this rulemaking has the potential to increase 
compliance with existing regulations, it would be appropriate for 
the analysis conducted under Executive Order 12866 and 13563 to 
include both cost and benefits estimates that reflect the new 
compliance. This is not, however, a legal requirement of the OSH 
Act. OSHA knows of no way to make such estimates and lacks any 
persuasive evidence in this rulemaking record that this rulemaking 
would affect compliance with the preceding PEL.
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Estimates of Incremental Benefits of the Final Rule
    Incremental costs and benefits are those that are associated with 
increasing the stringency of the standard. A comparison of incremental 
benefits and costs provides an indication of the relative efficiency of 
the final PEL and the alternative PEL. Again, OSHA has conducted these 
calculations for informational purposes only and has not used this 
information as the basis for selecting the PEL for the final rule.
    Tables VII-30A and VII-30B show result of estimates of the costs 
and benefits of reducing exposure levels from the preceding PELs of 
approximately 250 [micro]g/m\3\ (for construction and maritime) and 100 
[micro]g/m\3\ (for general industry) to the final rule PEL of 50 
[micro]g/m\3\ and to the alternative PEL of 100 [micro]g/m\3\, using 
the alternative discount rates of 3 and 7 percent. These tables also 
introduce a second alternative PEL. Under this second alternative 
standard, addressed in Tables VII-30A and VII-30B, the PEL would be 
lowered from 50 [micro]g/m\3\ to 25 [micro]g/m\3\ for all industries 
covered by the final rule, while the action level would remain at 25 
[micro]g/m\3\ (because of difficulties in accurately measuring exposure 
levels below 25 [micro]g/m\3\). For the construction sector under this 
second alternative, Table 1 requirements would also be modified to 
include respiratory protection for all workers covered under Table 1 
(because all exposures for Table 1 activities are assumed to be above 
25 [micro]g/m\3\), and all these covered workers would be subject to 
the medical surveillance provision.\126\
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    \126\ As with general industry and maritime employees, the 
limited number of construction workers not covered by Table 1 and 
estimated to exceed 25 [micro]g/m\3\ currently, such as abrasive 
blasters, are assumed to need respiratory protection under this 
alternative.
---------------------------------------------------------------------------

    Table VII-30A breaks out costs by provision and benefits by type of 
disease and by morbidity/mortality, while Table VII-30B breaks out 
costs and benefits by major industry sector or construction task 
sector. As Table VII-30A shows, at a discount rate of 3 percent, a PEL 
of 50 [micro]g/m\3\, relative to a PEL of 100 [micro]g/m\3\, imposes 
incremental costs of $381 million per year; incremental benefits of 
$4.3 billion per year, and additional net benefits of $3.9 billion per 
year. The final PEL of 50 [micro]g/m\3\ also has higher net benefits 
than 100 [micro]g/m\3\ either at a 3 percent or 7 percent discount 
rate.
    Table VII-30B continues this incremental analysis but with 
breakdowns between construction and general industry/maritime. As 
shown, both sectors show strong positive net benefits, which are 
greater for the final PEL of 50 [micro]g/m\3\ than the alternative of 
100 [micro]g/m\3\.
    The estimates in Tables VII-30A and VII-30B indicate that, across 
all discount rates, there are net benefits to be achieved by lowering 
exposures from the preceding PEL (250 [mu]g/m\3\ or 100 [mu]g/m\3\) to 
100 [mu]g/m\3\ and then, in turn, lowering them further to 50 [mu]g/
m\3\ and then to 25 [mu]g/m\3\, and the lower the PEL, the greater the 
net benefits.\127\ Net benefits decline across all incremental changes 
in PELs as the discount rate for annualizing benefits increases. The 
incremental net benefit of reducing the PEL from 100 [mu]g/m\3\ to 50 
[mu]g/m\3\ is greater than the incremental net benefit of reducing the 
PEL from 50 [mu]g/m\3\ to 25 [mu]g/m\3\ under both the 3 percent 
discount rate and the 7 percent discount rate.
---------------------------------------------------------------------------

    \127\ The lowest PEL considered as an alternative was 25 [mu]g/
m\3\. In addition, the costs exceed the benefits using the 7 percent 
discount rate for the 100 [mu]g/m\3\ alternative, since quantified 
benefits for the FEA are based entirely on the various quantitative 
risk assessments, and the PEL for general industry is already set at 
100 [mu]g/m\3\. (There would, however, be net benefits for 
construction.) As noted previously, the Agency is claiming no 
quantified benefits for the various ancillary provisions, such as 
medical surveillance.
---------------------------------------------------------------------------

    However, the majority of the benefits and costs that OSHA estimates 
for the final rule (PEL of 50 [mu]g/m\3\) are from the initial effort 
to lower exposures from the preceding PEL of 250 [mu]g/m\3\ in both 
construction and maritime to 100 [mu]g/m\3\, as shown in the 100 [mu]g/
m\3\ column and the Incremental Costs/Benefits column between the 100 
[mu]g/m\3\ column and the 50 [mu]g/m\3\ column in Table VII-30A. The 
majority of the costs and benefits attributable to lowering exposures 
to 100 [mu]g/m\3\ are in the construction industry. OSHA did not 
estimate any costs or benefits for general industry employers lowering 
exposures to an alternative of 100 [mu]g/m\3\ because the preceding PEL 
was already 100 [mu]g/m\3\, but a relatively small amount of costs and 
benefits would be attributed to maritime employers lowering exposures 
to the alternative of 100 [mu]g/m\3\ from the preceding PEL of 250 
[mu]g/m\3\. Because a single standard would cover both general industry 
and maritime employers, those costs and benefits are grouped together 
in Table VII-30A and VII-30B.
    In addition to examining alternative PELs, OSHA also examined 
alternatives to other provisions of the standard. These alternatives 
are discussed in the following Chapter VIII of the FEA: Regulatory 
Alternatives.
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5. Sensitivity Analysis
    In this section, OSHA presents the results of two different types 
of sensitivity analysis. In the first type of sensitivity analysis, 
OSHA made a series of isolated changes to individual cost and benefit 
input parameters in order to determine their effects on the Agency's 
estimates of annualized costs, annualized benefits, and annualized net 
benefits. In the second type of sensitivity analysis--a so-called 
``break-even'' analysis--OSHA also investigated isolated changes to 
individual cost and benefit input parameters, but with the objective of 
determining how much they would have to change for annualized costs to 
equal annualized benefits.
    Again, the Agency has conducted these calculations for 
informational purposes only and has not used these results as the basis 
for selecting the PEL for the final rule.
a. Analysis of Isolated Changes to Inputs
    The methodology and calculations underlying the estimation of the 
costs and benefits associated with this rulemaking are generally linear 
and additive in nature. Thus, the sensitivity of the results and 
conclusions of the analysis will generally be proportional to isolated 
variations a particular input parameter. For example, if the estimated 
time that employees need to travel to (and from) medical screenings is 
doubled, the corresponding labor costs double as well.
    OSHA evaluated a series of such changes in input parameters to test 
whether and to what extent the general conclusions of the economic 
analysis held up. OSHA first considered changes to input parameters 
that affected only costs and then changes to input parameters that 
affected only benefits. Each of the sensitivity tests on cost 
parameters had only a very minor effect on total costs or net costs. 
Much larger effects were observed when the benefits parameters were 
modified; however, in all cases, net benefits remained significantly 
positive. On the whole, OSHA found that the conclusions of the analysis 
are reasonably robust, as changes in any of the cost or benefit input 
parameters still show significant net benefits for the final rule. The 
results of the individual sensitivity tests are summarized in Table 
VII-31A and B and are described in more detail below.
    OSHA has tailored the sensitivity analysis to examine issues raised 
by commenters, particularly with respect to costs. (For more detail, 
see Chapter V of the FEA.) For each alternative, the estimated cost 
increase is equivalent to the estimated decrease in net benefits 
(except for minor rounding discrepancies). For instance, in the first 
example of sensitivity testing, when OSHA doubled the estimated portion 
of the affected self-employed population from 25 to 50 percent, and 
estimates of other input parameters remained unchanged, Table VII-31A 
shows that the estimated total costs of the final rule increased by 
$17.9 million annually, or by about 1.7 percent, while estimated net 
benefits also declined by $17.9 million, from $7,657 million to $7,639 
million annually.
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    In the second example, OSHA doubled the estimated familiarization 
time needed to understand the requirements of the new standard

[[Page 16619]]

relative to OSHA's best estimate, which ranged from 4 to 40 hours 
depending on establishment size (see Chapter V for more detail). As 
shown in Table VII-31A, if OSHA's estimates of other input parameters 
remained unchanged, the total estimated costs of the final rule 
increased by $16.0 million annually, or by about 1.5 percent, while net 
benefits declined by the same amount annually, from approximately 
$7,657 million to $7,641 million annually.
    In the third example, OSHA doubled the estimated daily amount of 
housekeeping per worker necessary to comply with the standard, from 10 
minutes to 20 minutes. As shown in Table VII-31A, if OSHA's estimates 
of other input parameters remained unchanged, the total estimated costs 
of the final rule increased by $12.5 million annually, or by about 1.2 
percent, while net benefits declined by the same amount annually, from 
approximately $7,657 million to $7,645 million annually.
    In the fourth example, OSHA examined the effect of increasing its 
estimate of the frequency with which thorough cleaning of the workplace 
would be performed in general industry. The Agency examined the effect 
of increasing the frequency from only one initial thorough cleaning to 
the initial cleaning plus an annual thorough cleaning, or alternately, 
a thorough cleaning every 5 years. As shown in Table VII-31A, if 
thorough cleaning were an annual cost, the total estimated costs of the 
final rule increased by $17.2 million annually, or by about 1.7 
percent, while net benefits declined by the same amount annually, from 
$7,657 million to $7,640 million annually. In the second variation of 
this test, for a thorough cleaning every 5 years, as shown in Table 
VII-31A, the increase in annual costs is only 0.2 percent.
    In the fifth example, OSHA increased its estimate of respirator 
use. In Chapter V of the FEA, OSHA explained that it calculated the 
costs of respirators for general industry and maritime workers who will 
still be exposed above the PEL after all feasible controls are in 
place. In addition, to be conservative, OSHA added costs to provide 
respirators to 10 percent of the remaining population. For this 
sensitivity test, OSHA doubled its estimate of the amount of additional 
respirator use in general industry from 10 percent to 20 percent. As 
shown in Table VII-31A, the total estimated costs of the final rule 
increased by $20.0 million annually, or by about 1.9 percent, while net 
benefits decreased by the same amount annually, from approximately 
$7,657 million to $7,637 million annually.
    In the sixth example, reflecting in part the range of comments the 
Agency received on the issue (discussed in detail in Chapter V), OSHA 
explored the effect of increasing, and alternately decreasing, by 50 
percent the size of the productivity impact arising from the use of 
engineering controls in construction. As shown in Table VII-31A, if 
OSHA's estimates of other input parameters remained unchanged, under 
the first variation, the total estimated costs of the final rule 
increased by $99.6 million annually, or by about 9.7 percent, while net 
benefits declined by the same amount annually, from $7,657 million to 
$7,558 million annually. Under the second variation, the decrease in 
costs and increase in net benefits would be of the same magnitude, with 
final estimated net benefits rising to $7,757 million.
    As shown in Table VII-31B, OSHA also performed sensitivity tests on 
several input parameters used to predict the benefits of the final 
rule. In the first two tests, in an extension of results previously 
presented in Table VII-27, the Agency examined the effect on annualized 
net benefits of employing the high-end estimate of the benefits, as 
well as the low-end estimate. As discussed previously, the Agency 
examined the sensitivity of the benefits to both the valuation of 
individual silica-related disease cases prevented, as well as the 
number of lung cancer deaths prevented. Table VII-31B presents the 
effect on annualized net benefits of using the extreme values of these 
ranges, the high count of cases prevented and the high valuation per 
case prevented, and the low count and the low valuation per case 
prevented. As indicated, using the high estimate of cases prevented and 
their valuation, the benefits rise by 45 percent to $12.6 billion, 
yielding net benefits of $11.5 billion. For the low estimate of both 
cases prevented and their valuation, the benefits decline by 45 
percent, to $4.8 billion, yielding net benefits of $3.8 billion.
    In the third sensitivity test of benefits, OSHA examined the effect 
of raising the discount rate for benefits to 7 percent. The fourth 
sensitivity test of benefits examined the effect of removing the 
adjustment to monetized benefits to reflect increases in real per 
capita income over time. The results of the first of these sensitivity 
tests for net benefits was previously shown in Table VII-29 and is 
repeated in Table VII-31B. Raising the interest rate to 7 percent 
lowers the estimated benefits by 45 percent, to $4.8 billion, yielding 
annualized net benefits of $3.8 billion. Removing the two-percent 
annual increase to monetized benefits to reflect increases in real per 
capita income over time decreases the benefits by 50 percent, to $4.3 
billion, yielding net benefits of $3.3 billion.
b. ``Break-Even'' Analysis
    OSHA also performed sensitivity tests on several other parameters 
used to estimate the net costs and benefits of the final rule. However, 
for these, the Agency performed a ``break-even'' analysis, asking how 
much the various cost and benefits inputs would have to vary in order 
for the costs to equal, or break even with, the benefits. The results 
are shown in Table VII-32.

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    OSHA also performed sensitivity tests on several other parameters 
used to estimate the net costs and benefits of the final rule. However, 
for these, the Agency performed a ``break-even'' analysis, examining 
how much the various cost and benefits inputs would have to vary in 
order for the costs to equal, or break even with, the benefits

[[Page 16621]]

estimated. The results are shown in Table VII-32.
    In the first break-even test on cost estimates, OSHA examined how 
much costs would have to increase in order for costs to equal estimates 
benefits. As shown in Table VII-32, this point would be reached if 
costs increased by $7.7 billion.
    In a second test, looking specifically at the estimated engineering 
control costs, the Agency found that these costs would also need to 
increase by $7.7 billion for costs to equal estimates benefits.
    In a third sensitivity test, on benefits, OSHA examined how much 
its estimated monetary valuation of an avoided illness or an avoided 
fatality would need to be reduced in order for the costs to equal the 
benefits. Since the total valuation of prevented mortality and 
morbidity are each estimated to exceed at least $2.6 billion, while the 
estimated costs are $1.0 billion, an independent break-even point for 
each is impossible. In other words, for example, if no value is 
attached to an avoided illness associated with the rule, but the 
estimated value of an avoided fatality is held constant, the rule still 
has substantial net benefits. Only through a reduction in the estimated 
net value of both components is a break-even point possible.
    OSHA, therefore, examined how large an across-the-board reduction 
in the monetized value of all avoided illnesses and fatalities would be 
necessary for the benefits to equal the costs. As shown in Table VII-
32, for costs to equal estimated benefits, the estimated value per life 
saved would have to decline to $1.10 million per life saved, and an 
equivalent percentage reduction to about $0.3 million per illness 
prevented.
    In a break-even sensitivity test, OSHA estimated how many silica-
related fatalities and illnesses would be required for benefits to 
equal costs. As shown in Table VII-32, a reduction of 88 percent, 
relative to the morbidity and mortality estimates is required to reach 
the break-even point--566 fewer fatalities prevented annually, and 809 
fewer silica-related illnesses prevented annually.

H. Regulatory Alternatives

    This section discusses several major regulatory alternatives to the 
final OSHA silica standard, pursuant to Executive Orders 13653 and 
12866. The presentation of regulatory alternatives in this chapter 
serves two important functions. The first is to demonstrate that OSHA 
explored less costly ways (compared to the final rule) to provide 
workers an adequate level of protection from exposure to respirable 
crystalline silica. The second is tied to the Agency's statutory 
requirement, which underlies the final rule, to reduce significant risk 
to the extent feasible. If OSHA had been unable to support its findings 
of significant risk and feasibility based on evidence presented during 
notice and comment, the Agency would then have had to consider 
regulatory alternatives that do satisfy its statutory obligations.
    Each regulatory alternative presented here is described and 
analyzed relative to the final rule. Where relevant, the Agency notes 
that some regulatory alternatives are not permissible based on the 
required legal findings OSHA has made regarding significant risk and 
feasibility. The regulatory alternatives have been organized into four 
categories similar to those used in the PEA: (1) Alternative PELs to 
the new PEL of 50 [mu]g/m\3\; (2) regulatory alternatives that affect 
ancillary provisions; (3) a regulatory alternative that would modify 
the methods of compliance; and (4) regulatory alternatives concerning 
when different provisions of the final rule would take effect.
Alternative PELs
    OSHA selected a new PEL for respirable crystalline silica of 50 
[mu]g/m\3\ for all industries covered by the final rule and developed 
and included Table 1 for many work activities within the construction 
sector. The final rule is based on the requirements of the Occupational 
Safety and Health Act (OSH Act) and court interpretations of the Act. 
For health standards issued under section 6(b)(5) of the OSH Act (29 
U.S.C. 655(b)(5)), OSHA is required to promulgate a standard that 
reduces the risk of material impairment of health to the extent that it 
is technologically and economically feasible to do so (see Section II, 
Pertinent Legal Authority, for a full discussion of the legal 
requirements for promulgating new health standards under the OSH Act).
    OSHA has conducted an extensive review of the literature on adverse 
health effects associated with exposure to respirable crystalline 
silica. The Agency has also developed estimates of the risk of silica-
related diseases assuming exposure over a working lifetime at the final 
PEL and action level, as well as at OSHA's preceding PELs. These 
analyses are presented in a background document entitled ``Respirable 
Crystalline Silica--Health Effects Literature Review and Preliminary 
Quantitative Risk Assessment'' and its final findings are described in 
this preamble in Section V, Health Effects, and Section VI, Final 
Quantitative Risk Assessment and Significance of Risk. The available 
evidence indicates that employees exposed to respirable crystalline 
silica well below the previous PELs are at increased risk of lung 
cancer mortality and silicosis mortality and morbidity. Occupational 
exposures to respirable crystalline silica also can result in the 
development of kidney and autoimmune diseases and in death from other 
nonmalignant respiratory diseases. As discussed in Section VI 
Significance of Risk, in this preamble, OSHA finds that worker exposure 
to respirable crystalline silica at the previous and new PELs 
constitutes a significant risk and that the final standard will 
substantially reduce this risk.
    Section 6(b) of the OSH Act (29 U.S.C. 655(b)) requires OSHA to 
determine that its standards are technologically and economically 
feasible. OSHA's examination of the technological and economic 
feasibility of the final rule is presented in the FEA, and is 
summarized in this section (Section VII) of this preamble. For general 
industry and maritime, OSHA has concluded that the final PEL of 50 
[mu]g/m\3\ is technologically feasible for all affected industries. In 
other words, OSHA has found that engineering and work practice controls 
will be sufficient to reduce and maintain silica exposures to the PEL 
of 50 [mu]g/m\3\ or below in most operations most of the time in the 
affected industries in general industry, and the rule is also feasible 
in maritime (feasibility for maritime (shipyards) partly depends on it 
being subject to other standards regulating abrasive blasting). For 
those few operations where the PEL cannot be achieved even when 
employers install all feasible engineering and work practice controls, 
employers in general industry and maritime can supplement controls with 
respirators to achieve exposure levels at or below the PEL.
    For construction, determined that the engineering and work practice 
controls specified in Table 1 are feasible for all affected activities 
and in most cases will keep exposures at or below 50 [mu]g/m\3\ most of 
the time. For those few activities where the engineering and work 
practice controls specified in Table 1 are not sufficiently protective 
of worker health, Table 1 specifies respirator use to supplement those 
controls. A limited number of activities, such as tunneling and 
abrasive blasting, are not dealt with under Table 1, but are governed 
more directly by the PEL of 50 [mu]g/m\3\, as in general industry and 
maritime. For construction, while a few tasks like abrasive blasting 
and those specified on Table 1 as requiring respirators cannot

[[Page 16622]]

achieve the PEL most of the time with engineering and work practice 
controls alone, OSHA has concluded that the PEL of 50 [mu]g/m\3\ is 
technologically feasible for the construction industry overall because 
most operations can meet the PEL using the specified controls in Table 
1or under the traditional approach.
    OSHA developed quantitative estimates of the compliance costs of 
the final rule for each of the affected industry sectors. The estimated 
compliance costs were compared with industry revenues and profits to 
provide a screening analysis of the economic feasibility of complying 
with the revised standard and an evaluation of the potential economic 
impacts. Industries with unusually high costs as a percentage of 
revenues or profits were further analyzed for possible economic 
feasibility issues. After performing these analyses, OSHA has concluded 
that compliance with the requirements of the final rule would be 
economically feasible in every affected industry sector.
    OSHA has examined two regulatory alternatives (named Regulatory 
Alternatives #1 and #2) that would modify the PEL for the final rule. 
Under Regulatory Alternative #1, the final PEL would be changed from 50 
[micro]g/m\3\ to 100 [micro]g/m\3\ for all industry sectors covered by 
the rule, and the action level would be changed from 25 [micro]g/m\3\ 
to 50 [micro]g/m\3\ (thereby keeping the action level at one-half of 
the PEL). Under Regulatory Alternative #2, the new PEL would be lowered 
from 50 [micro]g/m\3\ to 25 [micro]g/m\3\ for all industry sectors 
covered by the rule, while the action level would remain at 25 
[micro]g/m\3\ (because of difficulties in accurately measuring exposure 
levels below 25 [micro]g/m\3\). For the construction sector under this 
second alternative, Table 1 requirements would also be modified to 
include respiratory protection for all workers covered under Table 1 
(because none are expected to be mostly under 25 [micro]g/m\3\ for any 
of the tasks), and all these covered workers would be subject to the 
medical surveillance provision.
    Tables VII-33 and VII-34 present, for informational purposes, the 
estimated costs, estimated benefits, and estimated net benefits of the 
final rule under the new PEL of 50 [mu]g/m\3\ and for the regulatory 
alternatives of a PEL of 100 [mu]g/m\3\ and a PEL of 25 [mu]g/m\3\ 
(Regulatory Alternatives #1 and #2), using alternative discount rates 
of 3 and 7 percent. These two tables also present the incremental 
costs, the estimated incremental benefits, and the estimated 
incremental net benefits of going from a PEL of 100 [mu]g/m\3\ to the 
new PEL of 50 [mu]g/m\3\ and then of going from the new PEL of 50 
[mu]g/m\3\ to a PEL of 25 [mu]g/m\3\. Table VII-33 breaks out costs by 
provision and benefits by type of disease and by morbidity/mortality, 
while Table VII-34 breaks out costs and benefits by major industry 
sector.
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    As previously noted, Tables VII-33 and VII-34 also show the costs 
and estimated benefits of a PEL of 25 [mu]g/m\3\ (Regulatory 
Alternative #2), as well as

[[Page 16625]]

the incremental costs and benefits of going from the final PEL of 50 
[mu]g/m\3\ to a PEL of 25 [mu]g/m\3\. Because OSHA determined that a 
PEL of 25 [mu]g/m\3\ would not be feasible (that is, engineering and 
work practices would not be sufficient to reduce and maintain silica 
exposures to a PEL of 25 [mu]g/m\3\ or below in most operations most of 
the time in the affected industries), the Agency did not attempt to 
identify engineering controls or their costs for affected industries to 
meet this PEL. Instead, for purposes of estimating the costs of going 
from a PEL of 50 [mu]g/m\3\ to a PEL of 25 [mu]g/m\3\, OSHA assumed 
that all workers exposed between 50 [mu]g/m\3\ and 25 [mu]g/m\3\ would 
have to wear respirators to achieve compliance with the 25 [mu]g/m\3\ 
PEL. OSHA then estimated the associated additional costs for 
respirators, exposure assessments, medical surveillance, and regulated 
areas (the latter three for ancillary requirements specified in the 
final rule).
    As Tables VII-33 and VII-34 show, going from the final rule to 
Regulatory Alternative #2 (PEL of 25 [mu]g/m\3\) is estimated to 
prevent, annually, an additional 295 silica-related fatalities and an 
additional 122 cases of silicosis. These estimates support OSHA's 
finding that there is significant risk remaining at the final PEL of 50 
[mu]g/m\3\. However, the Agency has determined that a PEL of 25 [mu]g/
m\3\ is not technologically feasible for most sectors or operations, 
and for that reason, has not selected it.
Regulatory Alternatives That Affect Ancillary Provisions
    Section 6(b)(7) of the OSH Act, 29 U.S.C. 655(b)(7), requires 
standards to prescribe, where appropriate, the monitoring or measuring 
of employee exposure for the protections of employees. Section 6(b)(7) 
also requires the standards to prescribe, where appropriate, the type 
and frequency of medical exams to be provided by employers ``in order 
to most effectively determine whether the health of [exposed] employees 
is adversely affected by such exposure.'' The final rule contains 
several ancillary provisions (provisions other than the PEL), including 
requirements for exposure assessment, medical surveillance, 
familiarization and training, regulated areas (in general industry and 
maritime), and a written exposure control plan.
    OSHA's reasons for including each of the ancillary provisions are 
detailed in Section XV of this preamble, Summary and Explanation of the 
Standards. In particular, OSHA has determined that requirements for 
exposure assessment (or alternately, using specified exposure control 
methods for selected construction operations) provide a basis for 
ensuring that appropriate measures are in place to limit worker 
exposures. Medical surveillance is particularly important because 
workers exposed at levels below the new PEL are still at significant 
risk of death and illness (OSHA's decision not to lower the PEL further 
was due to limitations on technological feasibility, rather than a 
determination that significant risk was eliminated at the new PEL). 
Medical surveillance will allow for identification of respirable 
crystalline silica-related adverse health effects at an early stage so 
that appropriate intervention measures can be taken. Regulated areas 
and a written exposure control plan are important in part because they 
help limit exposure to respirable crystalline silica to as few 
employees as possible. Finally, worker training is necessary to inform 
employees of the hazards to which they are exposed, along with 
associated protective measures, so that employees understand how they 
can minimize potential health hazards. Worker training on silica-
related work practices is particularly important in controlling silica 
exposures because engineering controls frequently require action on the 
part of workers to function effectively.
    As shown in Table VII-33, these ancillary provisions represent 
approximately $340 million (or about 35 percent) of the total 
annualized costs of the final rule of $962 million (using a 3 percent 
discount rate). The three most expensive of the ancillary provisions 
are the requirements for medical surveillance, with annualized costs of 
$96 million; the requirements for training and familiarization, with 
annualized costs of $94 million; and exposure assessment, with 
annualized costs of $71 million.
    The requirements for exposure assessment in general industry and 
maritime are triggered by the action level. The exposures of workers in 
construction for whom all Table 1 requirements have been met do not 
have to be assessed, but if Table 1 requirements are not met, the 
requirements for exposure assessment in construction would also be 
triggered by the action level. As described in this preamble, OSHA has 
defined the action level for the standard as an airborne concentration 
of respirable crystalline silica of 25 [mu]g/m\3\ calculated as an 8-
hour time-weighted average. In this final rule, as in other OSHA health 
standards, the action level has been set at one-half of the PEL.
    As explained in Chapter IV of the FEA, OSHA finds that proper 
implementation of engineering and work practice controls, particularly 
those specified in Table 1, will eliminate much of the variability in 
silica exposure that characterizes baseline conditions in the general 
industry, maritime, and construction sectors. OSHA recognizes, however, 
that some variability is unavoidable and uncontrollable even with such 
controls. Because of this variability of employee exposures to airborne 
concentrations of respirable crystalline silica, maintaining exposures 
below the action level should provide reasonable assurance that 
employees will not be exposed to respirable crystalline silica at 
levels above the PEL on days when no exposure measurements are made. 
Even when all measurements on a given day fall between the PEL and the 
action level, there is some chance that on another day, when exposures 
are not measured, actual exposure may exceed the PEL. When exposure 
measurements are below the PEL but above the action level, the employer 
cannot be certain that employees have not been exposed to respirable 
crystalline silica concentrations in excess of the PEL during at least 
some part of the work week. Therefore, requiring periodic exposure 
measurements when the action level is exceeded provides the employer 
with a reasonable degree of confidence in the results of the exposure 
monitoring.
    As specified in the final rule, all workers in general industry and 
maritime exposed to respirable crystalline silica at or above the 
action level of 25 [mu]g/m\3\ are subject to the medical surveillance 
requirements. In the construction sector, medical surveillance is 
triggered by respirator use for 30 days or more per year (which 
generally corresponds to a risk of exposure above 50 [mu]g/m\3\ that 
prompted the Table 1 respirator requirement), For the final rule, the 
medical surveillance requirements will apply to an estimated 141,594 
workers in general industry and 270,581 workers in construction. OSHA 
estimates that 989 possible ILO 2/0 silicosis cases will be referred to 
specialists annually as a result of this medical surveillance.
    OSHA's conclusion is that the requirements triggered by the action 
level will result in a very real and necessary, but non-quantifiable, 
reduction in risk beyond that provided by the PEL alone. OSHA has 
determined that these ancillary provisions (periodic exposure 
assessment, medical surveillance in general industry/maritime) will 
reduce significant risk in at least three ways: (1) Providing economic 
incentives to employers to

[[Page 16626]]

reduce exposures to below 25 [mu]g/m\3\ to avoid the costs of medical 
surveillance and exposure monitoring; (2) helping to ensure the PEL is 
not exceeded; and (3) providing medical exams to workers exposed at the 
action level, resulting in additional specialist referrals for X-ray 
findings consistent with silicosis and allowing employees who find out 
they have a silica-related disease to take action, such as changing 
jobs or wearing a respirator for additional protection. In sum, the 
ancillary provisions triggered by the action level in the final rule 
provide significant benefits to worker health by providing additional 
layers and types of protection to employees exposed to respirable 
crystalline silica. Medical surveillance is particularly important for 
this rule because those exposed at the action level are still at 
significant risk of illness. OSHA did not estimate, and the benefits 
analysis does not include, monetary benefits resulting from early 
discovery of illness. OSHA's choice of using an action level for 
exposure monitoring of one-half of the PEL is based on the Agency's 
enforcement experience with other standards, including those for 
inorganic arsenic (29 CFR 1910.1018), ethylene oxide (29 CFR 
1910.1047), benzene (29 CFR 1910.1028), and methylene chloride (29 CFR 
1910.1052).
    In response to comments on the proposed rule and PEA, among other 
changes discussed in Chapter V, OSHA added familiarization costs and 
increased estimated training costs in the FEA, and increased the cost 
of an industrial hygienist when conducting exposure monitoring. These 
changes, however, were the result of OSHA revisions to its cost 
estimates, not changes to the text of the regulation. Medical 
surveillance and exposure assessments were the ancillary provisions 
that were the focus of regulatory alternatives in the PEA. For these 
reasons, the Agency has examined four regulatory alternatives 
(Regulatory Alternatives #3, #4, #5, and #6) involving changes to one 
or the other of these two ancillary provisions. These four regulatory 
alternatives are defined below and the incremental cost impact of each 
is summarized in Table VII-35. In addition, OSHA has qualitatively 
considered a regulatory alternative (Regulatory Alternative #7) that 
would remove all ancillary provisions.

[[Page 16627]]

[GRAPHIC] [TIFF OMITTED] TR25MR16.114

    Under Regulatory Alternative #3, the action level would be raised 
from 25 [micro]g/m\3\ to 50 [micro]g/m\3\ in the standard for general 
industry and maritime, while keeping the PEL at 50 [micro]g/m\3\. As a 
result, exposure monitoring and medical surveillance requirements would 
be triggered only if workers were exposed above 50 [micro]g/m\3\. No 
changes would be made to the construction standard because the medical 
surveillance trigger for that standard is respirator use, not an action 
level. As shown in Table VII-35, Regulatory Alternative #3 would reduce 
the annualized cost of the final rule by about $85 million, using a 
discount rate of 3 percent, and about $86 million using a discount rate 
of 7 percent.
    Under Regulatory Alternative #4, the action level in general 
industry and maritime would remain at 25 [micro]g/m\3\ but

[[Page 16628]]

medical surveillance would now be triggered by the PEL, not the action 
level. As a result, medical surveillance requirements would be 
triggered only if workers in general industry and maritime were exposed 
above the PEL of 50 [micro]g/m\3\. No changes would be made to the 
construction standard. This alternative is similar to Alternative #3, 
but because the action level would remain lower, the amount of exposure 
monitoring would not decrease in Alternative #4 (applicable to general 
industry and maritime (and for construction employers following the 
exposure monitoring method of compliance)), exposure monitoring is 
required when levels exceed the action level). As shown in Table VII-
35, Regulatory Alternative #4 would reduce the annualized cost of the 
final rule by about $28 million, using a discount rate of 3 percent and 
about $29 million using a discount rate of 7 percent).
    Under Regulatory Alternative #5, the only change to the final rule 
would be to the medical surveillance frequency requirements. Instead of 
requiring qualifying workers to be offered a medical check-up every 
three years, an annual medical check-up would be required to be 
offered. Assuming all workers will accept this offer, as shown in Table 
VII-35, Regulatory Option #5 would increase the annualized cost of the 
final rule by about $110 million, using a discount rate of 3 percent 
(and by about $108 million, using a discount rate of 7 percent).
    Under Regulatory Alternative #6, medical surveillance would be 
triggered by the PEL (in general industry and maritime), not the action 
level, and all workers (including in construction) subject to medical 
surveillance would be required to have a medical check-up annually 
rather than triennially. As shown in Table VII-35, Regulatory 
Alternative #6 would cause a net increase of the annualized cost of the 
final rule by about $42 million, using a discount rate of 3 percent 
(and by about $40 million, using a discount rate of 7 percent).
    While the Agency expects there will be substantial benefits related 
to its ancillary provisions, it does not have the same quantitative 
basis for estimating benefits, and therefore does not have quantitative 
estimates for the benefits of the preceding four regulatory 
alternatives.
    The final regulatory alternative affecting ancillary provisions, 
Regulatory Alternative #7, would eliminate all of the ancillary 
provisions of the final rule, including exposure assessment, medical 
surveillance, training, regulated areas, and the written exposure 
control plan. This alternative would be difficult to justify legally in 
light of 29 U.S.C. 655(b)(5) and (b)(7) along with case law requiring 
OSHA to use ancillary provisions to reduce significant risk remaining 
at the PEL when these provisions result in more than a de minimis 
benefit to workers (see Section II, Pertinent Legal Authority). In any 
event, it should be noted that elimination of the ancillary provisions 
does not mean that all costs for ancillary provisions would disappear. 
In order to meet the PEL, employers would still commonly need to 
conduct exposure monitoring, train workers on the use of controls, and 
set up some kind of regulated areas (in general industry and maritime) 
to indicate where respirator use would be required. It is also likely 
that some employers would follow the many recommendations to provide 
medical surveillance for employees and establish a written exposure 
control plan. OSHA has not attempted to estimate the extent to which 
the costs of these activities would be reduced if they were not 
formally required.
    OSHA finds that the benefits estimated under the final rule will 
not be fully achieved if employers do not implement the ancillary 
provisions of the final rule. For example, OSHA believes that the 
effectiveness of the final rule depends on regulated areas and the 
written exposure control plan to further limit exposures and on medical 
surveillance to identify disease cases when they do occur. For 
construction work, the written exposure control plan is an integral 
part of the overall scheme to protect workers engaged in activities 
covered by Table 1. Without this provision, workers would risk 
exposures from the activities of others and exposure monitoring would 
need to be significantly increased to ensure protection for those 
workers.
    Both industry and worker groups have recognized that a 
comprehensive standard, as opposed to a PEL alone, is needed to protect 
workers exposed to respirable crystalline silica. For example, the 
industry consensus standards for crystalline silica, ASTM E 1132--06, 
Standard Practice for Health Requirements Relating to Occupational 
Exposure to Respirable Crystalline Silica, and ASTM E 2626--09, 
Standard Practice for Controlling Occupational Exposure to Respirable 
Crystalline Silica for Construction and Demolition Activities, as well 
as the draft proposed silica standard for construction developed by the 
Building and Construction Trades Department, AFL-CIO, have each 
included comprehensive programs. These recommended standards include 
provisions for methods of compliance, exposure monitoring, training, 
and medical surveillance (Document ID 1466; 1504; 1509.
3. A Regulatory Alternative That Modifies the Methods of Compliance
    The final standard in general industry and maritime requires 
employers to implement engineering and work practice controls to reduce 
employees' exposures to or below the PEL. Where engineering and/or work 
practice controls are insufficient, employers are still required to 
implement them to reduce exposure as much as possible, and to 
supplement them with a respiratory protection program. Under the final 
construction standard, employers are given two options for compliance. 
The first option specifies, in Table 1 of the final rule, the exposure 
control methods and respiratory protection required for compliance when 
performing the specified task or operating the specified machines. 
Employers choosing this option must fully and properly implement the 
control methods and respiratory protection on the table to be 
considered to be in compliance with Table 1. The second option largely 
follows the requirements in the general industry and maritime standard: 
employers must conduct exposure monitoring and provide sufficient 
controls to ensure that their workers are not exposed above the PEL.
    One regulatory alternative (Regulatory Alternative #8) involving 
methods of compliance would be to eliminate Table 1 as a compliance 
option in the construction sector. This was suggested by one commenter 
(Document ID 1950), as a means of promoting innovation.
    As discussed in the Summary and Explanation in detail, OSHA 
fashioned the final rule as a sensible compromise between providing 
clear direction for employers, in a manner that reduces compliance 
burdens, and allowing for flexibility and innovation when desired. 
Table 1 is an option in the final rule that promotes both goals. While 
OSHA assumes that most establishments will choose to follow Table 1, in 
part to avoid the cost of monitoring, it is not a requirement. 
Employers are free to follow the other option (paragraph (d) of the 
standard) and conduct the required monitoring and devise their own 
means of complying with the PEL if they choose. To eliminate Table 1, 
therefore, would actually provide less flexibility and impose 
additional costs upon employers. OSHA therefore did not quantify costs 
or benefits for eliminating Table 1. Nonetheless, the Agency

[[Page 16629]]

seriously doubts that there would be any additional benefits under 
Alternative #8, and concludes that removing the Table 1 option would 
significantly increase exposure monitoring costs by taking away a 
carefully crafted ``safe harbor'' provision from employers.
Regulatory Alternatives That Affect the Timing of the Standard
    The final rule will become effective 90 days following publication 
of the final rule in the Federal Register. The provisions outlined in 
the construction standard will become enforceable one year following 
the effective date, except for those governing sample analysis (two 
years). The provisions set forth in the general industry and maritime 
standards will become enforceable two years following the effective 
date, with the exception that the engineering and work practice control 
requirements in the hydraulic fracturing industry will become 
enforceable five years after the effective date.
    There are many theoretical options that OSHA could explore with 
regard to compliance dates. These include: Requiring the fracking 
industry to follow the same compliance schedule as all other general 
industry and maritime employers; going back to the dates originally 
proposed (one year for engineering controls, two years for 
laboratories, six months for all other provisions); allowing more time 
for all employers to comply with the final rule; or allowing less time 
for all employers to come into compliance. These options are explored 
in detail in the Summary and Explanation for DATES. As indicated in 
that discussion, there are technical issues, and there may be 
additional costs, associated with advancing the compliance dates ahead 
of those laid out in the final rule; in all cases, pushing back the 
compliance deadlines will also push back the onset of benefits 
generated by the final rule. OSHA has not quantified the costs or 
benefits of either advancing or delaying any of the compliance dates 
because the timing of the effective dates has the same percentage 
effect on both benefits and costs.

I. Final Regulatory Flexibility Analysis

    The Regulatory Flexibility Act, as amended in 1996, requires an 
agency to prepare a Final Regulatory Flexibility Analysis (FRFA) 
whenever it promulgates a final rule that is required to conform to the 
notice-and-comment rulemaking requirements of section 553 of the 
Administrative Procedure Act (APA) (see 5 U.S.C. 601-612). For OSHA 
rulemakings, the FRFA analysis must contain:

    1. A statement of the need for, and objectives of, the rule;
    2. a statement of the significant issues raised by the public 
comments in response to the initial regulatory flexibility analysis, 
a statement of the assessment of the agency of such issues, and a 
statement of any changes made in the proposed rule as a result of 
such comments;
    3. the response of the agency to any comments filed by the Chief 
Counsel for Advocacy of the Small Business Administration (SBA) in 
response to the proposed rule, and a detailed statement of any 
change made to the proposed rule in the final rule as a result of 
the comments;
    4. a description of and an estimate of the number of small 
entities to which the rule will apply or an explanation of why no 
such estimate is available;
    5. a description of the projected reporting, recordkeeping and 
other compliance requirements of the rule, including an estimate of 
the classes of small entities which will be subject to the 
requirement and the type of professional skills necessary for 
preparation of the report or record; and
    6. a description of the steps the agency has taken to minimize 
the significant economic impact on small entities consistent with 
the stated objectives of applicable statutes, including a statement 
of the factual, policy, and legal reasons for selecting the 
alternative adopted in the final rule and why each one of the other 
significant alternatives to the rule considered by the agency which 
affect the impact on small entities was rejected; and for a covered 
agency, as defined in section 609(d)(2), a description of the steps 
the agency has taken to minimize any additional cost of credit for 
small entities. 5 U.S.C. 604.

    The Regulatory Flexibility Act further states that the required 
elements of the FRFA may be performed in conjunction with or as part of 
any other agenda or analysis required by any other law if such other 
analysis satisfies the provisions of the FRFA. 5 U.S.C. 605.
    In addition to these elements, OSHA also includes, in this section, 
the recommendations from the Small Business Advocacy Review (SBAR) 
Panel and OSHA's responses to those recommendations.
    While a full understanding of OSHA's analysis and conclusions with 
respect to costs and economic impacts on small entities requires a 
reading of the complete FEA and its supporting materials, this FRFA 
summarizes the key aspects of OSHA's analysis as they affect small 
entities.
The Need for and Objectives of the Rule
    Exposure to crystalline silica has been shown to increase the risk 
of several serious diseases. Crystalline silica is the only known cause 
of silicosis, which is a progressive respiratory disease in which 
respirable crystalline silica particles cause an inflammatory reaction 
in the lung, leading to lung damage and scarring, and, in some cases, 
to complications resulting in disability and death. In addition, many 
well-conducted investigations of exposed workers have shown that 
exposure increases the risk of mortality from lung cancer, chronic 
obstructive pulmonary disease (COPD), and renal disease. OSHA's 
detailed analyses of the scientific literature and silica-related 
health risks were presented in OSHA's Review of Health Effects 
Literature and Preliminary QRA in the NPRM (Document ID 1711, pp. 7-
229), and are included in Section VI Significance of Risk in this 
preamble.
    OSHA reviewed numerous studies and found that they all demonstrated 
positive, statistically significant exposure-response relationships 
between exposure to crystalline silica and lung cancer mortality (see 
the Health Risk section in this preamble for more detail). In addition, 
OSHA noted that in 2009 the International Agency for Research on Cancer 
(IARC) reaffirmed its finding that respirable crystalline silica is a 
human carcinogen, identifying in its analysis an overall positive 
exposure-response relationship between cumulative exposure to 
crystalline silica and lung cancer mortality (see Section VI, 
Significance of Risk; Document ID 1711, pp. 269-292). Based on studies, 
OSHA estimates that the lifetime lung cancer mortality excess risk 
associated with 45 years of exposure to respirable crystalline silica 
ranges from 11 to 54 deaths per 1,000 workers at the preceding general 
industry PEL of 100 [micro]g/m\3\ respirable crystalline silica, with 
that risk reduced to 5 to 23 deaths per 1,000 workers at the new PEL of 
50 [micro]g/m\3\ respirable crystalline silica.
    OSHA has also quantitatively evaluated the mortality risk from non-
malignant respiratory disease, including silicosis and COPD. Risk 
estimates for silicosis mortality are based on a study by Mannetje et 
al. (2002b, Document ID 1089), as reanalyzed by ToxaChemica, Inc. 
(2004, Document ID 0469), which pooled data from six worker cohort 
studies to derive a quantitative relationship between silica exposure 
and death rate for silicosis. For non-malignant respiratory disease 
generally, risk estimates are based on an epidemiologic study of 
diatomaceous earth workers, which included a quantitative exposure-
response analysis (Park et al., 2002, Document ID 0405). For 45 years 
of exposure to the preceding general industry PEL, OSHA's estimates of 
excess lifetime risk are 11 silicosis deaths per 1,000 workers for

[[Page 16630]]

the pooled analysis and 85 non-malignant respiratory disease deaths per 
1,000 workers based on Park et al.'s (2002) estimates (Document ID 
0405). At the new PEL, OSHA estimates silicosis and non-malignant 
respiratory disease mortality at 7 and 44 deaths per 1,000, 
respectively. As noted by Park et al. (2002) (Document ID 0405), it is 
likely that silicosis as a cause of death is often misclassified as 
emphysema or chronic bronchitis; thus, Mannetje et al.'s analysis of 
deaths may tend to underestimate the true risk of silicosis mortality, 
while Park et al.'s (2002) analysis would more fairly capture the total 
respiratory mortality risk from all non-malignant causes, including 
silicosis and COPD.
    OSHA also identified five studies that quantitatively described 
relationships between exposure to respirable crystalline silica and 
silicosis morbidity, as diagnosed from chest radiography. Based on the 
results of these studies, OSHA estimates a cumulative risk for 
silicosis morbidity of 60 to 773 cases per 1,000 workers for a 45-year 
exposure to the preceding general industry PEL of 100 [micro]g/m\3\ 
respirable crystalline silica, and 20 to 170 cases per 1,000 workers 
exposed at the new PEL of 50 [micro]g/m\3\ (see Section VI, 
Significance of Risk, Table VI-1).
    OSHA's estimates of crystalline silica-related renal disease 
mortality risk are derived from an analysis by Steenland et al. (2002, 
Document ID 0448), in which data from three cohort studies were pooled 
to derive a quantitative relationship between exposure to silica and 
the relative risk of end-stage renal disease mortality. The cohorts 
included workers in the U.S. gold mining, industrial sand, and granite 
industries. OSHA's analysis for renal disease mortality shows estimated 
lifetime excess risk of 39 deaths per 1,000 workers at the preceding 
general industry PEL of 100 [micro]g/m\3\ respirable crystalline 
silica, and 32 deaths per 1,000 workers exposed at the new PEL of 50 
[micro]g/m\3\ (see Section VI, Significance of Risk, Table VI-1).
    The objective of the final rule is to reduce the numbers of 
fatalities and illnesses occurring among employees exposed to 
respirable crystalline silica in general industry, maritime, and 
construction sectors. This objective will be achieved by requiring 
employers to install engineering controls where appropriate and to 
provide employees with the equipment, respirators, training, exposure 
monitoring, medical surveillance, and other protective measures 
necessary for them to perform their jobs safely. The legal basis for 
the rule is the responsibility given to the U.S. Department of Labor 
through the Occupational Safety and Health Act of 1970 (OSH Act). The 
OSH Act provides that, in promulgating health standards dealing with 
toxic materials or harmful physical agents, the Secretary ``shall set 
the standard which most adequately assures, to the extent feasible, on 
the basis of the best available evidence, that no employee will suffer 
material impairment of health or functional capacity even if such 
employee has regular exposure to the hazard dealt with by such standard 
for the period of his working life.'' 29 U.S.C. 655(b)(5) (see Section 
II, Pertinent Legal Authority for a more detailed discussion).
Summary of Significant Issues Raised by Comments on the Initial 
Regulatory Flexibility Analysis (IRFA) and OSHA's Assessment of, and 
Response to, Those Issues
    Small business representatives commented on all aspects of this 
rule, and their comments and OSHA's responses are covered throughout 
this preamble and the FEA. This section of the FRFA focuses only on 
comments that directly concern this FRFA or the screening analysis that 
precedes it.
    One commenter questioned the use of SBA definitions for small 
businesses, arguing that some definitions include firms with 500 
employees or more, which, according to the commenter, are too large to 
constitute ``small'' businesses. The commenter commended OSHA for also 
including an analysis of very small entities with fewer than 20 
employees (Document ID 2351, Attachment 1, p. 8). OSHA determined that 
both the analysis of the impacts on SBA-defined small entities and the 
analysis of the impacts on very small entities (those with fewer than 
twenty employees) are useful and important for examining small business 
impacts.
    Two commenters were concerned that their industries had not been 
covered in the IRFA. The American Railroad Association noted that small 
railroads had not been covered (Document ID 2366, Attachment 1, p. 4). 
The commenter is correct that OSHA did not examine small entities in 
this sector in the IRFA. For the FEA, OSHA has added a discussion of 
small entities in the railroad industry to Chapter VI, Economic 
Impacts. The Sorptive Minerals Institute also stated that their 
industry was not covered in the IRFA (Document ID 4230, Attachment 1, 
p. 16). As discussed in Chapter IV, the sorptive mineral industry was 
covered as part of a larger industry. In any case, OSHA has excluded 
exposures that result from the processing of sorptive clays from the 
scope of the final rule.
    Many commenters were concerned that OSHA had not used economic data 
that included the effects of the recent ``great recession''. This issue 
was addressed in the Chapter VI Introduction, but some commenters 
specifically discussed this topic in reference to small entities 
(Document ID 1822, Attachment 1, p. 1; 2187, Attachment 1, p. 2; 2322, 
p. 13; 3433, p. 8; 4231, Attachment 1, pp. 15-17). Complete data of the 
kind that OSHA needs for a thorough analysis of economic impacts were 
not yet available at the time the PEA was developed. As discussed in 
Chapter II, Industrial profile, the FEA, including this FRFA, uses 
2012, the most recent year with complete data, as a base year and used 
average profits from years including the recession and surrounding 
years.
    Some commenters were concerned with OSHA's estimates of small 
business profits. One commenter pointed out that OSHA had relied 
entirely on C corporation data, even though many affected firms might 
be S corporations, partnerships or sole proprietorships (Document ID 
2296, Attachment 1, p. 23). This is true, but there are no published 
data on S corporation, partnership, or sole proprietorship profits, and 
thus C corporation data is the best available data. As another 
commenter pointed out, reported profits of small business are generally 
lower than the total returns earned by owners who also act as 
executives for their firms. The same commenter explained that smaller 
firms have a great deal of flexibility in deciding what portions of 
entity gains are reported as profits, what portions are reported as 
management salaries, and what portions are reported as management 
bonuses (Document ID 2163, Attachment 1, p. 7). As a result, it is 
possible that OSHA has underestimated small firm profits and thus 
overestimated potential impacts on profits.
    Stuart Sessions argued that OSHA should have analyzed whether 
smaller firms have higher or lower profits than larger firms (Document 
ID 4231, Attachment 1, pp. 11-12). The limited data supplied by Mr. 
Sessions, however, did not show that small firms either had larger or 
smaller profits than bigger firms on an across-industry basis (Document 
ID 4231, Attachment 1, p. 11). Mr. Sessions developed an economic model 
that used a combination of multiple data sources to determine profit 
rates of small firms (RMA and BizMiner). In Chapter III Industrial 
Profile, Revenue and Profit,

[[Page 16631]]

OSHA discusses why the Agency's analysis does not use these alternate 
data sources suggested by Mr. Sessions. Mr. Sessions, testifying on 
behalf of the Construction Industry Safety Coalition, also testified 
that the use of data aggregated to the four-digit NAICS code level in 
OSHA's analysis shields small businesses from being captured properly 
in the analysis, and that ``the analysis at the six-digit level would 
show substantial impacts for masonry contractors who are small business 
. . ., which the analysis currently doesn't show'' (Document ID 3580, 
Tr. 1402). Mr. Sessions further claimed that, even though OSHA analyzed 
the costs to employers with 20 or fewer employees, the analysis still 
``hid'' a lot of small businesses (Document ID 3580, Tr. 1402). The use 
of Internal Revenue Service's Corporation Source Book profit data at a 
four-digit NAICS code level is explained in Chapter III along with a 
discussion explaining why alternative data sources suggested by Mr. 
Sessions are not applied in the FEA.
    At least one commenter argued that OSHA might have inaccurately 
estimated small firm revenues as a result of OSHA's method of 
projecting revenues for years when Census data are not available 
(Document ID 4231, Attachment 1, pp. 15-17). This argument is now moot, 
as OSHA is using data from the 2012 Economic Census, and is not using 
projected revenues in this analysis.
    Some commenters argued that OSHA had not adequately accounted for 
diseconomies of scale in small firms (Document ID 4231, Attachment 1, 
pp. 2-5; 2307, Attachment 10, p. 25; 2322, Attachment 1, pp. 15-16). 
During his testimony, Stuart Sessions testified that it was his ``guess 
. . . that small businesses are substantially more likely to be 
noncompliant currently than large businesses,'' and requested that OSHA 
conduct additional analysis to ``handle the differential compliance 
rates between small and large business'' (Document ID 3580, Tr. 1399). 
As discussed in Chapter V, OSHA has changed its approach to estimating 
costs of small firms to account for diseconomies of scale in small 
firms. However, there is no evidence, other than Mr. Sessions's 
``guess,'' that small firms are less compliant than large firms.
    Janet Kaboth, testifying on behalf of a small company in the brick 
manufacturing industry, stated that small businesses are more impacted 
by the rule because they have more difficulty accessing capital to 
upgrade engineering controls:

    [Engineering controls] must be purchased and paid for in the 
first year of compliance. . . . It is extremely unlikely that a 
small entity such as Whitacre Greer would be able to obtain a bank 
loan . . . for something that does not reduce costs or increase 
revenue and additionally adds cost (Document ID 3589, Tr. 3397-
3399).

    As discussed in Chapter VI, Economic Impacts, small firms will 
typically be able to pay for the first year costs of engineering 
controls from a single year's profits. Thus, there is no need to 
account for possible difficulties in obtaining credit.
    A different commenter requested that OSHA provide additional 
guidance in Table 1 of the construction standard as a way to mitigate 
the impact on small businesses (Document ID 2322, p. 6). OSHA has done 
so, and agrees that it will likely ease compliance for small 
construction businesses because it provides them with task-specific 
guidance that will allow them to avoid more complicated exposure 
monitoring processes.
    Many companies, associations, and private individuals submitted 
comments requesting a new SBAR Panel based a number of changes that 
have occurred since the SBAR Panel for this rule was held in 2003. The 
first and most common concern was that the economic data and 
information gathered during the Panel have become outdated and do not 
represent the dramatic changes in economic conditions that have 
resulted from the boom and bust economic cycle that occurred in the 
years following 2003 (Document ID 2224, p. 2; 2004, p. 1; 3580, Tr. 
1274-1276; 1779, p. 2; 1767, p. 2; 1783, p. 1; 2140, p. 1; 3495, p. 2; 
1798, p. 6; 1811, pp. 1-2; 2023, p. 1; 2222, p. 1; 2224, p. 2; 2230, p. 
1; 2248, Attachment 1, p. 5; 2294, p. 2; 2300, p. 2; 2305, p. 13; 2279, 
p. 11; 2289, p. 9; 2391, p. 2; 3275, pp. 2-3; 2075, p. 4; 2083, p. 1; 
2114, Attachment 1, p. 2; 2150, p. 2; 2170, Attachment 1, p. 1; 2210, 
Attachment 1, pp. 1-2; 4194, p. 5; 4210, Attachment 1, p. 2; 4217, 
Attachment 1, p. 7). Some commenters claimed that their industries have 
not recovered from the recession of 2008 and feel that their economic 
circumstances as small entities have changed as a result (Document ID 
1779, p. 2; 1767, p. 2; 1783, p. 1; 2140, p. 1; 3495, p. 2).
    OSHA conducted the SBAR Panel early in the rulemaking process in 
order to address small business concerns during the development of the 
proposed rule. The Agency used information gathered during the SBAR 
Panel to make significant changes to the proposed rule itself, as well 
as to the cost, impact, and other analyses contained in the proposal. 
OSHA's proposal contained six pages of tables that described every 
recommendation from the SBAR Panel, along with the Agency's responses.
    OSHA's extensive rulemaking process included small business 
feedback not only from the original SBREFA review in 2003, but also 
from the subsequent written comment period in 2013 and 2014, as well as 
from the public hearings held in 2014. The rulemaking record shows the 
major issues that arose with respect to technological feasibility, 
costs, economic feasibility, and possible alternatives to the proposed 
rule represented largely the same issues addressed by small entity 
representatives (SERs) in 2003. To the extent there may be new issues 
that have arisen since the SBAR Panel made its recommendations, OSHA is 
confident that commenters, including small entities and the Small 
Business Administration's Office of Advocacy, were able to raise those 
issues and express whatever concerns they had about them later in the 
rulemaking process. OSHA has addressed comments regarding recent and 
current economic conditions under which small businesses are operating 
by considering this information in developing the final rule and 
supporting analyses.
    A second concern raised by commenters who were advocating for OSHA 
to hold a new SBAR Panel, related to the changes in technology and work 
practices that have taken place over the last ten years. For example, 
one commenter claimed that the comments of the SERs were not reflective 
of the greater use of tools with dust collection capability, and other 
devices currently being used that release water at the point of 
cutting, to control silica dust (Document ID 2210, Attachment 1, p. 1). 
However, the commenters who wanted OSHA to account for improved 
technology and work practices did not generally provide information to 
supplement or update the information OSHA received from the SERs, 
despite opportunities to do so.
    While there has been progress in the development and adoption of 
technologies that reduce silica exposures, the record (including 
comments from the commenters calling for a new Panel) brought out few, 
if any, fundamentally new technologies for reducing silica exposure. In 
any event, the advancement of technologies that would improve silica 
control or reduce the cost impact of the final rule would not 
necessitate a new SBAR panel.
    There were also a number of construction firms that expressed 
disappointment at not being able to

[[Page 16632]]

comment on Table 1, as presented in the proposed rule, prior to the 
proposed rule being issued (Document ID 2187, p. 22; 4217, Attachment 
1, p. 7; 3580, Tr. 1274-1276). It is typical for OSHA to modify a rule 
as a result of the SBREFA process. The SBREFA process is a one-time 
requirement, not a requirement to conduct a new Panel every time a rule 
is altered in response to SBAR Panel recommendations. The commenters, 
who did have the opportunity to comment on Table 1 once it was 
proposed, did not present any compelling argument regarding how the 
timing of their opportunity to comment impacted their ability to 
communicate their recommendations about Table 1 to OSHA. The Agency 
notes that it has made a number of significant changes to Table 1 since 
the proposal, most in response to post-proposal comments, so it is 
clear that commenters had ample opportunities to recommend improvements 
to Table 1.
    No SERs from the hydraulic fracturing industry were included in the 
2003 SBAR panel. OSHA did not determine that this industry would be 
affected by this rule until the preparation of the NPRM and the PEA. As 
a result, OSHA has received comments from associations and businesses 
requesting a new SBAR Panel that would allow a more detailed analysis 
of the potential impacts on small entities in this industry. Commenters 
pointed out that the unique economic circumstances of the hydraulic 
fracturing industry were not presented for public comment or analysis 
on regulatory alternatives and small business impacts during the 
Agency's 2003 SBAR Panel (Document ID 2301, Attachment 1, p. 63; 3589, 
pp. 15-16; 2288, p. 5).
    OSHA is not required to assure that every industry affected by a 
rule is represented on the Panel by a SER. The hydraulic fracturing 
industry had extensive opportunities to comment throughout this 
rulemaking process. In fact, a number of commenters, including several 
trade associations, submitted comments and testified at the hearing, 
providing analysis of the hydraulic fracturing industry for the record. 
OSHA sees no indication that the record would be better developed by 
convening a different SBAR panel with a SER from the hydraulic 
fracturing industry. OSHA has, however, extended the compliance 
deadline for these firms to install the required engineering controls 
required by this final rule to five years; three more years than for 
establishments in general industry and four more years than for 
construction firms.
Response to Comments by the Chief Counsel for Advocacy of the Small 
Business Administration and OSHA's Response to Those Comments
    The Chief Counsel for Advocacy of the Small Business Administration 
(``Advocacy'') provided OSHA with comments on this rule on February 11, 
2014 (Document ID 2349). Advocacy provided comment on OSHA's risk 
assessment and benefits analysis; technological feasibility analysis; 
cost analysis; current economic conditions; preferred alternatives; and 
procedural issues.
Risk Assessment and Benefits Issues
    With respect to the risk assessment, Advocacy was concerned that 
OSHA was attributing benefits to reducing the PEL to 50 [mu]g/m\3\ that 
perhaps would better be attributed to eliminating exposures above the 
existing PEL of 100 [mu]g/m\3\ (Document ID 2349, pp. 3-4). OSHA does 
not think this is the case. As discussed in the section on significant 
risk, OSHA did not assess the risk of silica exposure by attributing 
existing known cases of silicosis or any other disease to various PELs. 
Rather, OSHA examined risk assessment studies that assessed the long 
term consequences of various levels of exposure to silica. Such studies 
focus on estimating the morbidity and mortality that result from 
changing lifetime exposure levels from the preceding PELs of 100 [mu]g/
m\3\ in general industry and 250 [mu]g/m\3\ in construction to the new 
PEL of 50 [mu]g/m\3\.
    Advocacy also expressed concerns about the accuracy of older 
exposure data (Document ID 2349, p. 4). OSHA's exposure profile, used 
for examining feasibility and benefits, now shows only exposures 
measured after 1990 and includes data from OSHA's OIS system for 2011 
to 2014.
    Advocacy was also concerned that OSHA might not have adequately 
accounted for varying risk levels associated with different types of 
silica (Document ID 2349, p. 4). OSHA carefully considered this issue 
in the risk assessment section and found there were insufficient data 
to demonstrate significant risk for silica exposures that result from 
processing sorptive clays. As a result, OSHA excluded this processing 
activity from the scope of the final standard. OSHA found that, while 
the risk from other forms of silica may vary, there is evidence of 
significant risk for all of the other forms of respirable crystalline 
silica.
    Advocacy also reported that small business representatives were 
concerned that ``OSHA's assumption that silica exposure occurs over a 
working life of eight hours per day for 45 years does not reflect 
modern working conditions'' (Document ID 2349, p. 4). OSHA is required 
by the OSH Act to consider the risk of a hazard over a worker's entire 
working life (see 29 U.S.C. 655(b)(5)). In Chapter VII of the FEA, OSHA 
also examined other possible average tenure assumptions.
    Advocacy also reported that small business representatives ``noted 
the uncertainty of assessing silica-related risk because of confounding 
factors, such as smoking or exposure to other chemicals, and the long 
latency period for silica-related illness to appear'' (Document ID 
2349, p. 4). OSHA notes in Section VI, Significance of Risk, in this 
preamble that study after study finds that incidence of the diseases 
caused by exposure to silica rises with increasing exposures to silica. 
In order to see this type of result, and for those results to be driven 
by smoking as a confounding factor, it would be necessary not just that 
the silica-using population smoke more than the comparable non-silica 
using population, but also that smoking rates rise as silica exposures 
increase. This seems very unlikely and there is no evidence in the 
record that this is the case.
Technological Feasibility Issues
    Advocacy noted that small business representatives had raised many 
concerns about whether the controls OSHA indicated as appropriate to 
achieve the PEL were feasible in all circumstances and could, in fact, 
allow an employer to fully achieve the PEL (Document ID 2349, p. 4). 
OSHA has thoroughly examined all comments on this kind of issue across 
all affected industries in Chapter IV of the FEA, and OSHA notes that 
employers may raise infeasibility as a defense in enforcement actions. 
Advocacy also noted that small business representatives were concerned 
about whether available methods of measuring exposure were sufficiently 
accurate to correctly measure the action level and PEL (Document ID 
2349, p. 4). OSHA has explained in Chapter IV of the FEA why existing 
equipment is sufficiently accurate to correctly measure airborne 
respirable silica at the levels established by the new PEL and action 
level.
    Advocacy said that one small business representative ``noted that 
increasing the volume of air needed for additional ventilation could 
result in a violation of a facility's air permit'' (Document ID 2349, 
p. 5). While the Agency does not believe that most small employers 
exhaust large enough volumes of air that the additional

[[Page 16633]]

ventilation required by this final standard will result in needing to 
alter air permits, OSHA does acknowledge that this may be an issue for 
some employers. In order to reduce the burden, should this be the case, 
OSHA has given general industry employers an additional year to meet 
the PEL, and has added costs for firms subject to air permitting 
requirements to alter their permits to more fully assess the economic 
feasibility of this rule.
    Advocacy also said that one small business representative ``noted 
that creating regulated areas is not feasible in many open-design 
facilities'' (Document ID 2349, p. 5). Regulated area requirements have 
been a part of OSHA health standards for many years and employers have 
consistently found ways to make them work. The Agency does not expect 
that establishing a regulated area for silica would be any more 
difficult than establishing such an area for any of the other 
substances for which OSHA has regulated area requirements. In addition, 
OSHA does not have a regulated area requirement in construction where 
workplaces (such as in road building or repair) are more mobile.
Cost Issues
    Advocacy stated that small business representatives generally felt 
that OSHA underestimated costs, and were particularly concerned about 
OSHA's ``cost per exposed worker'' approach and OSHA's estimates of the 
number of workers whose exposures are controlled per engineering 
control (Document ID 2349, p. 5). The specific methodological issues 
that Advocacy mentions are issues for OSHA's general industry and 
maritime cost estimates, but not for construction cost estimates 
because the cost estimation methodologies for the construction sector 
are quite different and do not use the ``cost per exposed worker'' 
approach. OSHA has provided detailed responses to comments on costs in 
Chapter V. In general industry and maritime, OSHA continues to use the 
cost per exposed worker approach and defends this approach in Chapter 
V. OSHA has lowered its estimate of the number of workers whose 
exposures are reduced per engineering control in response to comments 
from small business representatives and others.
    Advocacy also noted that small business representatives objected to 
OSHA focusing on the incremental cost of moving from the preceding PELs 
to the new PEL. Advocacy reported that small business representatives 
believed OSHA should have included the costs of reaching the preceding 
PEL in its analysis (Document ID 2349, p. 5). Contrary to Advocacy's 
suggestion, OSHA did not conduct the analysis this way because it would 
require an assumption that employers are not complying with OSHA's 
existing requirements to meet the preceding PEL, but would now choose 
to comply with a more stringent requirement. OSHA's exposure profiles 
do indicate that many employers are failing to meet the preceding PELs, 
but the question that the Agency has to address with this analysis for 
this rulemaking is whether OSHA should require employers to meet a 
lower PEL than the preceding PEL. The costs of meeting the preceding 
PEL are not relevant to that decision.
Issues Concerning Current Economic Conditions
    Advocacy reported that ``small business representatives stated that 
OSHA was using older economic data that does not reflect current 
economic conditions, and [thus] that OSHA's cost pass-through 
assumptions are unrealistic'' (Document ID 2349, p. 5). For the FEA, 
OSHA is using 2012 as the base year for economic data and includes data 
from the recent recession in analyzing average industry profits and 
historical changes in profits and prices. OSHA has updated its findings 
on the ability of firms to pass costs on to buyers in light of the 
updated data, resolving Advocacy's concern on this issue.
Regulatory Alternatives
    Advocacy commended OSHA for following the advice of small business 
representatives and adopting the Table 1 approach for the construction 
sector, but urged OSHA to make the table clearer, more workable, and 
more specific, and to relieve employers of any remaining duty to 
conduct exposure monitoring when engaged in Table 1 tasks (Document ID 
2349, p. 6). OSHA has revised Table 1, as Advocacy and small business 
representatives suggested, to provide employers with a clear 
alternative to exposure monitoring and to provide greater clarity and 
specificity in the descriptions of controls.
    Advocacy also urged OSHA to consider the option of leaving the PEL 
unchanged and instead improving enforcement, noting that this was the 
option most favored by small business representatives (Document ID 
2349, p. 3). However, the OSH Act commands OSHA to protect workers from 
harmful substances by setting

. . . the standard which most adequately assures, to the extent 
feasible, on the basis of the best available evidence, that no 
employee will suffer material impairment of health or functional 
capacity even if such employee has regular exposure to the hazard 
dealt with by such standard for the period of his working life.'' 29 
U.S.C. 655(b)(5).

The record does not indicate that workers are currently protected in 
accordance with the Act. There are currently two entirely different 
PELs, 100 [mu]g/m\3\ in general industry and 250 [mu]g/m\3\ in 
construction. The record does not suggest either that employers in 
construction cannot feasibly reach a lower PEL or that there is no 
significant risk below 250 [mu]g/m\3\. The record shows that most 
employers in construction currently reach a PEL of 50 [mu]g/m\3\ most 
of the time (see Chapter IV) and that it is economically feasible to do 
so (see Chapter VI).
    OSHA did consider the option of lowering the construction PEL to 
100 [mu]g/m\3\ and leaving the general industry PEL unchanged. However, 
this action would not be in accordance with the OSH Act given that 
there is still significant risk at a PEL of 100 [mu]g/m\3\ and that a 
lower PEL is both technologically and economically feasible. As shown 
in OSHA's risk assessment, there is still significant risk of material 
impairment of health at levels all the way down to a lower PEL of 25 
[mu]g/m\3\, but OSHA found compliance with the lower PEL of 25 [mu]g/
m\3\ to be technologically infeasible for all industries.
    Finally, Advocacy urged OSHA to consider the option of abandoning 
the hierarchy of controls, which is OSHA's longstanding policy of 
preferring engineering controls and administrative controls over 
personal protective equipment such as respirators (Document ID 2349, 
pp. 4-5). This issue is addressed in the summary and explanation 
section discussion of the methods of compliance provision. It should 
also be noted that OSHA defines technological feasibility in terms of 
what can be accomplished with engineering controls, not in terms of 
what can be accomplished with respirators.
Issues With Respect to Small Business Participation
    Advocacy also expressed concern that small businesses did not have 
adequate opportunity for participation in the rulemaking process and 
that the SBAR panel was held over ten years before the proposed rule 
was issued (Document ID 2349, p. 7). OSHA responded to these concerns 
in section two of this FRFA.

[[Page 16634]]

A Description and Estimate of the Number of Small Entities To Which the 
Rule Will Apply
    OSHA has analyzed the impacts associated with this final rule, 
including the type and number of small entities to which the standard 
will apply. In order to determine the number of small entities 
potentially affected by this rulemaking, OSHA used the definitions of 
small entities developed by the Small Business Administration (SBA) for 
each industry.
    OSHA estimates that approximately 646,000 small business or 
government entities would be affected by the silica standard. Within 
these small entities, roughly 1.4 million workers are exposed to 
crystalline silica and would be protected by this final standard. A 
breakdown, by industry, of the number of affected small entities is 
provided in Table III-6 in Chapter III of the FEA.
    OSHA estimates that approximately 579,000 very small entities would 
be affected by the silica standard. Within these very small entities, 
roughly 785,000 workers are exposed to crystalline silica and would be 
protected by the standard. A breakdown, by industry, of the number of 
affected very small entities is provided in Table III-7 in Chapter III 
of the FEA.
A Description of the Projected Reporting, Recordkeeping, and Other 
Compliance Requirements of the Rule
    Tables VII-36 and VII-37 show the average costs of the silica 
standard and the costs of compliance as a percentage of profits and 
revenues by NAICS code for, respectively, small entities (classified as 
small by SBA) and very small entities (those with fewer than 20 
employees). The costs for SBA defined small entities ranges from a low 
of $295 per entity for entities in NAICS 238200 Building Equipment 
Contractors, to a high of about $161,651 for NAICS 213112 Support 
Activities for Oil and Gas Operations.
    The cost for very small entities ranges from a low of $223 for 
entities in NAICS 238200 Building Equipment Contractors, to a high of 
about $119,072 for entities in NAICS 213112 Support Activities for Oil 
and Gas Operations.
    Tables VII-38a and VII-38b show the unit costs which form the basis 
for OSHA's cost estimates for the average small entity and very small 
entity.
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[[Page 16651]]

Description of the Steps OSHA Has Taken To Minimize the Significant 
Economic Impact on Small Entities Consistent With the Stated Objectives 
of Applicable Statutes and Statement of the Reasons for Selecting the 
Alternative Adopted in the Final Rule
    OSHA has made a number of changes in the final silica rule that 
will serve to minimize significant impacts on small entities consistent 
with the objectives of the OSH Act.
    First, OSHA has made two changes to the scope of the rule that will 
minimize impacts for small business. OSHA has eliminated from the scope 
of the rule exposures that result from the processing of sorptive 
clays. OSHA's analysis did not determine whether any or all of the 
processers of sorptive minerals are small businesses, but to the extent 
they are, this change will reduce impacts on such entities. OSHA has 
also rewritten the scope of the rule with respect to the coverage of 
employers whose employees are exposed to silica at levels below the 
action level. The final rule does not apply to employers in general 
industry and maritime where the employer has objective data 
demonstrating that employee exposure to respirable crystalline silica 
will remain below 25 [mu]g/m\3\ as an 8-hour time-weighted average 
under any foreseeable conditions, and does not apply in construction 
where employee exposure will remain below 25 [mu]g/m\3\ as an 8-hour 
time-weighted average under any foreseeable conditions (see Scope in 
Section XV, Summary and Explanation of the Standards). OSHA expects 
that these changes may remove all compliance duties for some small 
businesses, possibly including carpenters, plumbers, and electricians, 
whose employees' only exposures to respirable crystalline silica is in 
small amounts for short-duration tasks that are performed infrequently.
    OSHA also revised Table 1 for the construction industry in ways 
that will minimize impacts on small businesses. OSHA requested comment 
on the approach for construction in the NPRM. After carefully reviewing 
the comments received on this issue, the Agency significantly revised 
the structure of the construction rule to focus on the tasks known to 
generate high exposures to respirable crystalline silica and to expand 
Table 1 to cover almost all of them (tunnel boring and abrasive 
blasting are the exceptions). Under this final rule, where employers 
fully and properly implement the specified engineering controls, work 
practices, and respiratory protection for each employee engaged in a 
task identified on Table 1, the employer is not also required to 
conduct exposure assessments to determine compliance with the PEL. 
Specifying the kinds of dust controls for construction tasks that are 
expected to reduce exposures to the 50 [micro]g/m\3\ target, as an 
option in lieu of a performance-oriented approach involving a PEL and 
regular exposure assessment, will make compliance easier for 
construction employers. Some commenters indicated that this specific 
guidance is particularly beneficial to small businesses that may not 
have as many resources to develop their own compliance plans (e.g., 
Document ID 2322-A1, p. 16). The Agency also revised the notes and 
specifications on Table 1 to clarify what is required for employers to 
fully and properly implement the specified engineering controls, work 
practices, and respiratory protection for tasks on Table 1 (see 
Specified Exposure Control Methods in Section XV, Summary and 
Explanation of the Standards).
    After carefully reviewing the comments received on respiratory 
protection requirements for the construction standard and the exposure 
data in the record (described in Chapter IV of the FEA), OSHA 
identified those situations where respiratory protection is necessary 
and made significant revisions to the respiratory protection 
requirements specified on Table 1 based on those findings. The result 
is that respiratory protection is not required for most of the tasks 
covered by Table 1 (see Specified Exposure Control Methods in Section 
XV, Summary and Explanation of the Standards).
    For this final rule, the Agency has significantly revised the 
requirements for initial exposure assessment and periodic exposure 
assessment in order to provide employers with greater flexibility. The 
standard allows the employer to use either the performance option or 
the scheduled monitoring option for initial and periodic exposure 
assessments. OSHA also clarified that the performance option provides 
employers with flexibility in the methods used to assess employee 
exposures, and provided examples of how employers can accurately 
characterize employee exposures using the performance option (see 
Exposure Assessment discussion in Section XV, Summary and Explanation 
of the Standards).
    At the suggestion of many commenters, OSHA has eliminated regulated 
area/access control plan requirements in construction. Employers in 
construction now have more flexibility in determining the best way to 
control exposures through a written exposure control plan.
    In the final rule, OSHA has agreed with many commenters to 
eliminate the requirements for protective clothing, and thus has 
reduced costs to small businesses.
    OSHA requested comment on the use of wet methods as a substitute 
for dry sweeping in the NPRM. After carefully reviewing the comments 
received on this issue, the Agency revised the provision to prohibit 
dry sweeping only where such activity could contribute to employee 
exposure to respirable crystalline silica. Moreover, the standard 
contains an exception to the prohibition on dry sweeping in such 
circumstances if wet sweeping, HEPA-filtered vacuuming, or other 
methods that minimize the likelihood of exposure are not feasible (see 
Housekeeping in Section XV, Summary and Explanation of the Standards).
    In the NPRM, OSHA requested comment on the prohibition of employee 
rotation to achieve compliance when exposure levels exceed the PEL. 
After carefully reviewing the comments received on this issue, OSHA 
removed the prohibition on employee rotation from the rule (see Methods 
of Compliance in Section XV, Summary and Explanation of the Standards).
    OSHA examined the issue of a 30-day exemption in the NPRM. After 
carefully reviewing the comments received on this issue, the Agency 
decided not to include a 30-day exemption from the requirement to 
implement engineering and work practice controls. However, OSHA 
clarified that where engineering controls are not feasible, such as for 
certain maintenance and repair activities, the use of respirators is 
permitted (see Methods of Compliance and Respiratory Protection in 
Section XV, Summary and Explanation of the Standards).
    OSHA adopted these alternatives to reduce costs and regulatory 
burdens consistent with the requirements of the OSH Act and court 
interpretations of the Act. For health standards issued under section 
6(b)(5) of the OSH Act, OSHA is required to promulgate a standard that 
reduces significant risk to the extent that it is technologically and 
economically feasible to do so (see Section II, Pertinent Legal 
Authority, for a full discussion of OSHA legal requirements).
    OSHA has conducted an extensive review of the literature on adverse 
health effects associated with exposure to respirable crystalline 
silica. The Agency has also developed estimates of the risk of silica-
related diseases

[[Page 16652]]

assuming exposure over a working lifetime at the proposed PEL and 
action level, as well as at OSHA's preceding PELs. These analyses are 
summarized in this preamble in Section V, Health Effects and 
Quantitative Risk Analysis. The available evidence indicates that 
employees exposed to respirable crystalline silica well below the 
preceding PELs are still at increased risk of lung cancer mortality and 
silicosis mortality and morbidity. Occupational exposures to respirable 
crystalline silica also may result in the development of kidney and 
autoimmune diseases and in death from other nonmalignant respiratory 
diseases, including chronic obstructive pulmonary disease (COPD).
    As discussed in Section VI, Significance of Risk, in this preamble, 
OSHA determined that worker exposure to respirable crystalline silica 
constitutes a significant risk and that the final standard will 
substantially reduce this risk. Further, there is significant risk well 
below the new PEL of 50 [mu]g/m\3\, but OSHA has determined that 
achieving a PEL of 25 [mu]g/m\3\ is not technologically feasible.
    Section 6(b) of the OSH Act requires OSHA to determine that its 
standards are technologically and economically feasible. OSHA's 
examination of the technological and economic feasibility of the final 
rule is presented in the FEA and FRFA. OSHA has concluded that the new 
PEL of 50 [mu]g/m\3\ is technologically feasible for all affected 
sectors in general industry and maritime and that Table 1 is 
technologically feasible for construction.
    For those few operations where the new PEL is not technologically 
feasible, even when workers use recommended engineering and work 
practice controls, employers can supplement controls with respirators 
to achieve exposure levels at or below the new PEL.
    OSHA developed quantitative estimates of the compliance costs of 
the final rule for each of the affected industry sectors in Chapter V 
of the FEA. The estimated compliance costs were compared with industry 
revenues and profits to provide a screening analysis of the economic 
feasibility of complying with the revised standard and an evaluation of 
the potential economic impacts in Chapter VI of the FEA. Industries 
with unusually high costs as a percentage of revenues or profits were 
further analyzed for possible economic feasibility issues. After 
performing these analyses, OSHA has concluded that compliance with the 
requirements of the final rule will be economically feasible in every 
affected industry sector.
    OSHA has also provided analyses of the costs and benefits of 
alternative PELs, though it should be pointed out these are for 
informational purposes only. Benefit cost analysis cannot be used as a 
decision criteria for OSHA health standards under the OSH Act. OSHA has 
examined two regulatory alternatives (named Regulatory Alternatives #1 
and #2) that would have modified the PEL for the final rule. Under 
Regulatory Alternative #1, the PEL would have been 100 [mu]g/m\3\ for 
all affected industry sectors, and the action level would have been 50 
[mu]g/m\3\ (thereby keeping the action level at one-half of the PEL). 
For the construction sector under Regulatory Alternative #1, Table 1 
requirements for respirator use would have been eliminated for all 
workers performing Table 1 tasks. Under this alternative, only abrasive 
blasters and underground construction workers would have been required 
to wear respiratory protection, and only workers wearing respirators in 
these operations would have been subject to the medical surveillance 
provision. Under Regulatory Alternative #2, the PEL would have been 25 
[mu]g/m\3\ for all affected industry sectors, while the action level 
would have remained at 25 [mu]g/m\3\ (because of difficulties in 
accurately measuring exposure levels below 25 [mu]g/m\3\). For the 
construction sector under Regulatory Alternative #2, Table 1 
requirements would have been modified to include respiratory protection 
for all workers covered under Table 1, and all these covered workers 
would have been subject to the medical surveillance provision.
    Table VII-39 presents, for informational purposes, the estimated 
costs, benefits, and net benefits of the final rule under Regulatory 
Alternatives #1 and #2, using alternative discount rates of 3 and 7 
percent. The tables also present the incremental costs, the incremental 
benefits, and the incremental net benefits of going from a PEL of 100 
[mu]g/m\3\ to the new PEL of 50 [mu]g/m\3\ and then of going from the 
new PEL of 50 [mu]g/m\3\ to a PEL of 25 [mu]g/m\3\ for general industry 
and maritime, as well as the effects in construction of the 
corresponding changes to Table 1 under Regulatory Alternatives #1 and 
#2. Table VII-39 breaks out costs by provision and benefits by type of 
disease and by morbidity/mortality.
    Because OSHA determined that a PEL of 25 [mu]g/m\3\ would not be 
feasible (that is, engineering and work practices would not be 
sufficient to reduce and maintain silica exposures to a PEL of 25 
[mu]g/m\3\ or below in most operations most of the time in the affected 
industry sectors in general industry and maritime), the Agency did not 
attempt to identify engineering controls or their costs for this 
alternative PEL. Instead, for purposes of estimating the costs of going 
from a PEL of 50 [mu]g/m\3\ to a PEL of 25 [mu]g/m\3\, OSHA assumed 
that all workers exposed between 50 [mu]g/m\3\ and 25 [mu]g/m\3\ would 
have to wear respirators to achieve compliance with a PEL of 25 [mu]g/
m\3\. OSHA then estimated the associated additional costs for 
respirators, exposure assessments, medical surveillance, and regulated 
areas (the latter three for ancillary requirements specified in the 
final rule). For the construction sector under Regulatory Alternative 
#2, as previously indicated, Table 1 requirements would be modified to 
include respiratory protection for all covered workers, and all covered 
workers would be subject to the medical surveillance provision.
    As shown in Table VII-39, going from the final rule to Regulatory 
Alternative #2 would prevent, annually, an additional 295 silica-
related fatalities and an additional 122 cases of silicosis. These 
estimates support OSHA's finding that there is significant risk 
remaining at the new PEL of 50 [mu]g/m\3\. However, the Agency has 
determined that it cannot select Regulatory Alternative #2 because a 
PEL of 25 [mu]g/m\3\ is not technologically feasible and this 
alternative would require extensive use of respirators for those using 
Table 1 under the construction standard (see the Technological 
Feasibility Summary in this preamble for a further discussion of the 
feasibility of a PEL of 25 [mu]g/m\3\).

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Recommendations From the SBAR Panel and OSHA's Responses
    Table VII-40 lists all of the SBAR Panel recommendations and OSHA's 
responses to these recommendations.
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BILLING CODE 4510-26-C

VIII. Paperwork Reduction Act

    The final general industry/maritime (``the general industry 
standard'') and construction standards (``the standards'') for 
respirable crystalline silica contain collections of information (also 
referred to as ``paperwork'' requirements) that are subject to review 
by the Office of Management and Budget (OMB). In accordance with the 
Paperwork Reduction Act (PRA) (44 U.S.C. 3506(c)(2)), OSHA solicited 
public comments on the Respirable Crystalline Silica Standards for 
General Industry, Shipyard Employment and Maritime Terminals (29 CFR 
1910.1053) and Construction (29 CFR 1926.1053) Information Collection 
Request (ICR) (paperwork burden hour and cost analysis) for the 
proposed rule. The Department also submitted this ICR to OMB for review 
in accordance with 44 U.S.C. 3507(d) on September 12, 2013. On January 
23, 2014, OMB authorized the Department to use OMB Control Number 1218-
0266 in future paperwork submissions involving this rulemaking. OMB 
commented, ``This OMB action is not an approval to conduct or sponsor 
an information collection under the Paperwork Reduction Act of 1995'' 
(see http://www.reginfo.gov/public/do/PRAViewICR?ref_nbr=201111-1218-004).
    The proposed rule invited the public to submit comments to OMB, in 
addition to OSHA, on the proposed collections of information with 
regard to the following:
     Whether the proposed collections of information are 
necessary for the proper performance of the Agency's functions, 
including whether the information is useful;
     The accuracy of OSHA's estimate of the burden (time and 
cost) of the collections of information, including the validity of the 
methodology and assumptions used;
     The quality, utility, and clarity of the information 
collected; and
     Ways to minimize the compliance burden on employers, for 
example, by using automated or other technological techniques for 
collecting and transmitting information (78 FR 56438).

No public comments were received specifically in response to the 
proposed ICR and supporting documentation submitted to OMB for review. 
However, public comments submitted in response to the Notice of 
Proposed Rulemaking (NPRM), described earlier in this preamble, 
substantively addressed collections of information and contained 
information relevant to the burden hour and costs analysis. OSHA 
considered these comments when it developed the revised ICR associated 
with these final rules.
    The Department of Labor submitted the final ICR on the date of 
publication, containing a full analysis and description of the burden 
hours and costs associated with the collections of information of the 
final rule, to OMB for approval. A copy of the ICR is available to the 
public at http://www.reginfo.gov/public/do/PRAViewICR?ref_nbr=201509-1218-004 (this link will only become active the day following 
publication of this notice). OSHA will publish a separate notice in the 
Federal Register that will announce the results of that review. That 
notice will also include a summary of the collections of information 
and burdens imposed by the new standard. A Federal agency cannot 
conduct or sponsor a collection of information unless it is approved by 
OMB under the PRA, and the collection of information notice displays a 
currently valid OMB control number (44 U.S.C. 3507(a)(3)). Also, 
notwithstanding any other provision of law, no employer shall be 
subject to penalty for failing to comply with a collection of 
information if the collection of information does not display a 
currently valid OMB control number (44 U.S.C. 3512).
    The major collections of information found in the standards are 
listed below.
BILLING CODE 4510-26-P

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BILLING CODE 4510-26-C
    The collections of information in the rule are needed to assist 
employers in identifying and controlling exposures to respirable 
crystalline silica in the workplace, and to address respirable 
crystalline silica-related adverse health effects. OSHA will also use 
records developed in response to these standards to determine 
compliance.
    The final rule imposes new collections of information for purposes 
of the PRA. In response to comments on the proposed rule, OSHA has 
revised provisions of the final rule that affect the collections of 
information. These revisions include:

--An exception in paragraph (a)(2) of the general industry standard for 
those circumstances where the employer has objective data demonstrating 
that employee exposure to respirable crystalline silica will remain 
below 25 micrograms per cubic meter of air (25 [mu]g/m\3\) as an 8-hour 
time-weighted average (TWA) under any foreseeable conditions. The 
construction standard also provides an exception where employee 
exposure will remain below 25 [mu]g/m\3\ as an 8-hour TWA under any 
foreseeable conditions (paragraph (a)). However, the exception in the 
construction standard does not require the employer to have objective 
data to support the exception.
--An additional exemption in the general industry standard for 
occupational exposures that result from the processing of sorptive 
clays (paragraph (a)(1)(iii)).
--Revisions to paragraph (d) of the general industry standard 
(paragraph (d)(2) for construction), which sets forth requirements for 
assessing employee exposures to respirable crystalline silica, 
including revisions to:
[cir] General requirements for exposure assessment. Paragraph (d)(1) of 
the general industry standard (paragraph (d)(2)(i) in construction) was 
revised and restructured to allow employers to use either the 
performance option or the scheduled monitoring option to meet their 
initial and periodic exposure assessment obligations. More 
specifically, these revisions include replacing the proposed (d)(1)(ii) 
and (d)(1)(iii), all of (d)(2), and (d)(3) with a simplified general 
requirement to assess exposures when exposures are expected to be at or 
above the action level using either the performance option or the 
scheduled monitoring option. Thus, the final rule does not contain an 
initial assessment requirement like the proposed rule. Initial 
monitoring is only required under the scheduled monitoring option and 
has to be performed as soon as work begins. The proposed standard 
included a requirement to assess the exposure of employees expected to 
be exposed to respirable crystalline silica at or above the action 
level, which consisted of an initial monitoring of employees, unless 
monitoring had been performed in the previous 12 months, or the 
employer had objective data to demonstrate that exposures would be 
below the action level under any expected conditions, as well as 
periodic exposure assessments, depending on the results of initial 
monitoring, following either a scheduled monitoring option or a 
performance option. These revisions from the proposed rule emphasize 
the performance option in order to provide additional flexibility for 
employers who are able to characterize employee exposures through 
alternative methods. However, the content of the performance option 
requirement remains the same as the content of the proposed 
requirement.

    [cir] OSHA has also not established time limitations for air 
monitoring results used to characterize employee exposures under the 
performance option. Although the proposed rule limited employers using 
air monitoring data for initial exposure assessment purposes to data 
obtained no more than twelve months prior to the rule's effective date, 
there were no such time restrictions on monitoring data used to conduct 
periodic exposure assessments under the performance option. 
Nevertheless, many commenters found the 12-month limit on the use of 
monitoring results for initial exposure assessments using existing data 
to be too restrictive. OSHA has been persuaded by these commenters not 
to establish time limitations for monitoring results used to assess 
exposures under the performance option, as long as the employer can 
demonstrate the data accurately characterize current employee exposures 
to respirable crystalline silica.
    [cir] Scheduled monitoring option. Paragraph (d)(3) of the general 
industry standard (paragraph (d)(2)(iii) for construction) describes 
the scheduled monitoring option, which provides employers with a 
clearly defined, structured approach to assessing employee exposures. 
OSHA made a number of minor changes to the requirements for periodic 
monitoring under the scheduled monitoring option (paragraphs 
(d)(3)(iii)-(d)(3)(v) of the general industry standard, paragraphs 
(d)(2)(iii)(C)-(d)(2)(iii)(E) in construction) to clarify that the 
``most recent'' exposure monitoring sample determines how often an 
employer must monitor.
    [cir] Revisions to requirements to reassess exposures. Paragraph 
(d)(4) of the general industry standard (paragraph (d)(2)(iv) in 
construction) requires employers assessing exposures using either the 
performance option or the scheduled monitoring option to reassess 
employee exposures whenever there has been a change in the production, 
process, control equipment, personnel, or work practices that may 
reasonably be expected to result in new or additional exposures to 
respirable crystalline silica at or above the action level, or when the 
employer has any reason to believe that new or additional exposures at 
or above the action level have occurred. OSHA added the phrase ``or 
when the employer has any reason to believe that new or additional 
exposures at or above the action level have occurred'' to the proposed 
language to make clear that

[[Page 16695]]

reassessment of exposures is required whenever there is reason to 
believe that a change in circumstances could result in new or 
additional exposures at or above the action level.

--The addition of paragraph (f)(2)(i) of the general industry standard 
(paragraph (g)(1) of the construction standard), which requires 
employers to establish and implement a written exposure control plan 
for all employees covered by the rule. Under paragraph (f)(2)(i)(A)-(C) 
(paragraphs (g)(1)(i)-(iii) of the construction standard), the written 
exposure control plan must contain a description of: The tasks in the 
workplace that involve exposure to respirable crystalline silica; the 
engineering controls, work practices, and respiratory protection used 
to limit employee exposure to respirable crystalline silica for each 
task; and a description of the housekeeping measures used to limit 
employee exposure to respirable crystalline silica. Paragraph 
(g)(1)(iv) of the construction standard requires the written exposure 
control plan to contain a description of the procedures used to 
restrict access to work areas, when necessary, to minimize the number 
of employees exposed to respirable crystalline silica and their level 
of exposure, including exposures generated by other employers or sole 
proprietors. OSHA did not propose a requirement for a written exposure 
control plan, but requested comment on whether to include one in the 
final rule. The final rule does not include the proposed written access 
control plan that the employer could prepare in lieu of establishing 
regulated areas that would only apply to areas with PEL exceedances.
--Alterations to paragraph (i)(1)(i) of the general industry standard, 
which requires employers to make medical surveillance available at no 
cost to the employee, and at a reasonable time and place, for each 
employee who will be occupationally exposed to respirable crystalline 
silica at or above the action level for 30 or more days per year. 
Paragraph (h)(1)(i) of the construction standard requires employers to 
make medical surveillance available to employees who will be required 
by the standard to use a respirator for 30 or more days per year. In 
the proposed standards, OSHA specified that employers must make medical 
surveillance available to those employees who would be occupationally 
exposed to respirable crystalline silica above the PEL for 30 or more 
days a year.
--Revisions to the medical surveillance exam requirements in paragraph 
(i)(2)(iii) of the standard (paragraph (h)(2)(iii) of the standard for 
construction), which allow digital X-rays, in addition to film X-rays, 
and no longer allow for an equivalent diagnostic study. The paragraph 
requires a chest X-ray (a single posteroanterior radiographic 
projection or radiograph of the chest at full inspiration recorded on 
film (no less than 14 x 17 inches and no more than 16 x 17 inches) or 
digital radiography systems) interpreted and classified according to 
International Labour Office (ILO) International Classification of 
Radiographs of Pneumoconiosis by a NIOSH-certified B Reader. The only 
substantive changes from the proposed provision are to (1) specifically 
allow for the use of digital systems because OSHA concluded that they 
are an equivalent diagnostic studies as film X-rays and (2) to no 
longer allow for the use of an equivalent diagnostic study because OSHA 
concluded there are currently no studies that are equivalent to film 
and digital X-rays.
--Minor edits to paragraphs (i)(4)(i)-(iv) of the general industry 
standard (paragraphs (h)(4)(i)-(iv) of the standard for construction), 
which is entitled: ``Information provided to the PLHCP.'' For example, 
in paragraphs (i)(4)(i) and (iv) (paragraphs (h)(4)(i) and (iv) in the 
standard for construction), ``affected employee'' was changed to 
``employee''. The word ``affected'' was removed because it is clear 
that the paragraphs refer to employees who will be undergoing medical 
examinations. In paragraph (i)(4)(iii) (paragraph (h)(4)(iii) in the 
standard for construction), ``has used the equipment'' was changed to 
``has used or will use the equipment'' to make it consistent with the 
earlier part of the paragraph that states ``personal protective 
equipment used or to be used''. Changes to these paragraphs are made to 
clarify OSHA's intent, which has not changed from the proposed rule.
--Revisions to the information required to be provided by the PLCHP to 
the employer and the employee. In response to public comments about 
employee privacy and potential discrimination or retaliation concerning 
medical findings, the final rule requires a detailed written medical 
report for the employee and a less detailed written medical opinion for 
the employer. This is a change from the proposed rule, which required 
the PLHCP to give the employer a written medical opinion that did not 
include findings unrelated to respirable crystalline silica exposure, 
and required the employer to give the employee a copy of the opinion.
    [cir] The contents of the written medical report for the employee 
are set forth in paragraphs (i)(5)(i)-(iv) of the general industry 
standard (paragraphs (h)(5)(i)-(iv) of the construction standard). They 
include: A statement indicating the results of the medical examination, 
including any medical condition(s) that would place the employee at 
increased risk of material impairment of health from exposure to 
respirable crystalline silica and any medical conditions that require 
further evaluation or treatment; any recommended limitations on the 
employee's use of respirators; any recommended limitations on 
respirable crystalline silica exposure; and a statement that the 
employee should be examined by a specialist if the chest X-ray provided 
in accordance with this section is classified as 1/0 or higher by the B 
reader, or if referral to a specialist is deemed appropriate by the 
PLHCP. The health-related contents of the PLHCP's report to the 
employee are fairly consistent with the proposed PLHCP's opinion to the 
employer, but two major exceptions are noted. Because only the employee 
will be receiving the written medical report, (1) the written medical 
report should include diagnoses and specific information on health 
conditions, including those not related to respirable crystalline 
silica and (2) medical conditions that require further evaluation or 
follow-up are not limited to those related to respirable crystalline 
silica exposure. Although the employer will not be responsible for 
further evaluation of conditions not related to respirable crystalline 
silica exposure, the PLHCP has an ethical obligation to inform the 
employee about those conditions. In addition, a minor difference from 
the proposed opinion is that the report specifies limitations of 
respirator use rather than personal protective equipment (PPE), because 
a respirator is the only type of PPE required under this rule.
    [cir] The contents of the PLHCP's written medical opinion for the 
employer are presented in paragraphs (i)(6)(i)(A)-(C) and 
(i)(6)(ii)(A)-(B) of the general industry standard (paragraphs 
(h)(6)(i)(A)-(C) and (h)(6)(ii)(A)-(B) of the construction standard). 
The contents of the written opinion are to include only the following: 
The date of the examination, a statement that the examination has met 
the requirements of the standard, and any recommended

[[Page 16696]]

limitations on the employee's use of respirators. Paragraphs 
(i)(6)(ii)(A)-(B) of the general industry standard (paragraphs 
(h)(6)(ii)(A)-(B) of the construction standard) state that if the 
employee provides written authorization, the written opinion provided 
to the employer must also contain: Any recommended limitations on 
exposure to respirable crystalline silica and a statement that the 
employee should be examined by a specialist if the chest X-ray provided 
in accordance with the standard is classified as 1/0 or higher by the B 
reader, or if referral to a specialist is otherwise deemed appropriate 
by the PLHCP. As noted above, OSHA proposed that the employer obtain a 
more detailed written medical opinion from the PLHCP. In the final 
rule, the only medically related information that is to be reported to 
the employer without authorization from the employee is limitations on 
respirator use.
    [cir] Under paragraph (i)(5) of the general industry standard 
(paragraph (h)(5) of the construction standard), the employer must 
ensure that the PLHCP explains the results of the examination to the 
employee and gives the employee a written report within 30 days of each 
medical examination performed. Under paragraphs (i)(6)(i) and 
(i)(6)(iii) of the general industry standard (paragraphs (h)(6)(i) and 
(h)(6)(iii) of the construction standard), employers must ensure that 
the PLHCP gives them and that the employee receives a copy of the 
employer's written medical opinion within 30 days of each medical 
examination. OSHA had proposed that the employer obtain the PLHCP's 
medical opinion within 30 days of the medical examination and then 
provide a copy to the employee within 2 weeks after receiving it.
    [cir] The proposed opinion for the employer called for a statement 
that the PLHCP had explained to the employee the results of the medical 
examination, including findings of any medical conditions related to 
respirable crystalline silica exposure that require further evaluation 
or treatment, and any recommendations related to use of protective 
clothing or equipment. As noted above, OSHA has retained the 
requirement that the employer ensure that the PLHCP explains the 
results to the employee in paragraph (i)(5) of the standard (paragraph 
(h)(5) of the standard for construction), but no longer requires the 
PLCHP to include a statement of this fact in the opinion for the 
employer. OSHA is not mandating how the employer ensures that the 
employee gets the required information because there are various ways 
this could be done, such as in a contractual agreement between the 
employer and PLHCP. PLHCPs could still include the verification in the 
PLHCP's opinion for the employer if that is a convenient method for 
them to do so.

--Changes to the provisions regarding referral to a specialist. 
Paragraphs (i)(5)(iv) and (i)(6)(ii)(B) of the general industry 
standard (paragraphs (h)(5)(iv) and (h)(6)(ii)(B) of the construction 
standard) specifies that the PHLCP include a statement that the 
employee should be examined by a specialist if the X-ray is classified 
as 1/0 or higher by the B reader, or if referral to a specialist is 
deemed appropriate by the PLHCP. Those paragraphs now indicate referral 
to a ``specialist.'' OSHA has added ``specialist'' to the definitions 
in paragraph (b) of the standards, to allow referrals to specialists 
who are American Board Certified in Pulmonary Disease or Occupational 
Medicine. OSHA proposed examination by an American Board Certified 
Specialist in Pulmonary Disease and concludes that expansion of the 
specialist definition to include board certified occupational medicine 
physicians will mean that more physicians will be available for 
referrals, making appointments easier to get.
--Changes to the requirements regarding information given by the 
specialist to the employer and employee. Under paragraph (i)(7)(iii) of 
the general industry standard (paragraph (h)(7)(iii) of the standard 
for construction), the employer must ensure that the specialist 
explains medical findings to the employee and gives the employee a 
written medical report (i.e., a report containing results of the 
examination, including conditions that might increase the employee's 
risk from exposure to respirable crystalline silica, conditions 
requiring further follow-up, recommended limitations on respirator use, 
and recommended limitations on respirable crystalline silica exposure, 
as required by paragraph (i)(5) except (i)(5)(iv) of the general 
industry standard ((h)(5) except (h)(5)(iv) of the construction 
standard). The reasons why the specialist is to give the employee this 
information and the changes from the proposed rule are discussed above, 
under the requirements for the PLHCP's report. Likewise, for the same 
reasons as addressed above, paragraph (i)(7)(iv) of the standard 
(paragraph (h)(7)(iv) of the standard for construction) requires the 
specialist to provide the employer with a medical opinion (i.e.,--an 
opinion indicating the date of the examination, any recommended 
limitations on the employee's use of respirators, and with the written 
authorization of the employee, any recommended limitations on the 
employee's exposure to respirable crystalline silica, as required by 
paragraph (i)(6) (except (i)(6)(i)(B) and (i)(6)(ii)(B)) of the general 
industry standard (paragraph (h)(6) (except (h)(6)(i)(B) and 
(h)(6)(ii)(B)) of the construction standard)).
--Changes to the requirements regarding maintenance of monitoring data 
records by employers. Paragraph (k)(1)(i) of the general industry 
standard (paragraph (j)(1)(i) of the construction standard), the 
substance of which remains unchanged from the proposed standards, 
requires the employer to make and maintain accurate air monitoring data 
records of all exposure measurements taken to assess employee exposure 
to respirable crystalline silica, as prescribed in paragraph (d) of the 
general industry standard (paragraph (d)(2) of the construction 
standard). OSHA has added the words ``make and'' prior to ``maintain'' 
in order to clarify that the employer's obligation is to create and 
preserve such records. The language in this provision is consistent 
with OSHA's standard on access to employee exposure and medical 
records, which refers to employee exposure and medical records that are 
made or maintained (29 CFR 1910.1020(b)(3)). This clarification has 
also been made for other records required by the silica rule (29 CFR 
1910.1053(k)(2)(i), 29 CFR 1910.1053(k)(3)(i), 29 CFR 
1926.1153(j)(2)(i), and 29 CFR 1926.1153(j)(3)(i)). In addition, OSHA 
now refers to ``measurements taken to assess employee exposure'' rather 
than ``measurement results used or relied on to characterize employee 
exposure'' in paragraph (k)(1)(i) of the general industry standard 
(paragraph (j)(1)(i) of the construction standard). This change is non-
substantive, and is intended to clarify OSHA's intent that all 
measurements of employee exposure to respirable crystalline silica be 
maintained.
--Changes to the requirement for maintaining air monitoring data 
records by employers. OSHA has made one modification in the rule to 
describe the information required in the records that differs from the 
proposed rule in paragraph (k)(1)(ii)(B) (paragraph (j)(1)(ii)(B) of 
the construction standard) and that is

[[Page 16697]]

to change ``the operation monitored'' to ``the task monitored.'' Both 
``task'' and ``operation'' are commonly used in describing work. 
However, OSHA uses the term ``task'' throughout the rule, and the 
Agency is using ``task'' in the recordkeeping provision for consistency 
and to avoid any potential misunderstanding that could result from 
using a different term. This change neither increases nor decreases an 
employer's obligations as set forth in the proposed standards.
--Changes to the requirements regarding maintenance of objective data 
records by employers. Paragraph (k)(2)(i) of the general industry 
standard (paragraph (j)(2)(i) for construction), the substance of which 
remains unchanged from the proposed rule, requires employers who rely 
on objective data to keep accurate records of the objective data. 
Paragraph (k)(2)(ii) of the general industry standard (paragraph 
(j)(2)(ii) of the construction standard) requires the record to 
include: The crystalline silica-containing material in question; the 
source of the objective data; the testing protocol and results of 
testing; a description of the process, task, or activity on which the 
objective data were based; and other data relevant to the process, 
task, activity, material, or exposures on which the objective data were 
based. Paragraphs (k)(2)(ii)(D) and (E) of the general industry 
standard (paragraphs (j)(2)(ii)(D) and (E) of the construction 
standard) have been modified from the proposed rule to substitute the 
word ``task'' for ``operation'', and to clarify the requirements for 
records of objective data. These changes do not affect the employer's 
obligations as set forth in the proposed standards.
--Changes to the requirements regarding the maintenance of medical 
surveillance records by employers. In paragraph (k)(3)(ii)(B) and (C) 
of the general industry standard (paragraph (j)(3)(ii)(B) and (C) of 
the construction standard), which requires employers to make and 
maintain medical surveillance records, OSHA has changed the ``PLHCP's 
and pulmonary specialist's written opinions'' to the ``PLHCPs' and 
specialists' written medical opinions.'' The change, consistent with 
paragraph (i) of the general industry standard (paragraph (h) of the 
construction standard), is made to reflect the revised definition for 
the term ``specialist'' included in the rule.

IX. Federalism

    The Agency reviewed the respirable crystalline silica rule 
according to the most recent Executive Order on Federalism, Executive 
Order 13132, which requires that Federal agencies, to the extent 
possible, refrain from limiting State policy options, consult with 
States before taking actions that would restrict States' policy 
options, and take such actions only when clear constitutional authority 
exists and the problem is of national scope (64 FR 43255 (8/10/1999)). 
The Executive Order allows Federal agencies to preempt State law only 
with the express consent of Congress. In such cases, Federal agencies 
must limit preemption of State law to the extent possible.
    Under Section 18 of the Occupational Safety and Health Act (29 
U.S.C. 667), Congress expressly provided that States may adopt, with 
Federal approval, a plan for the development and enforcement of 
occupational safety and health standards. OSHA refers to States that 
obtain Federal approval for such plans as ``State-Plan States.'' 
Occupational safety and health standards developed by State-Plan States 
must be at least as effective in providing safe and healthful 
employment and places of employment as the Federal standards. Subject 
to these requirements, State-Plan States are free to develop and 
enforce their own occupational safety and health standards.
    This rule complies with Executive Order 13132. The problems 
addressed by this new respirable crystalline silica rule are national 
in scope. As explained in Chapter VI, Final Quantitative Risk 
Assessment and Significance of Risk, employees face a significant risk 
of material health impairments from exposure to crystalline silica in 
the workplace. These employees are exposed to respirable crystalline 
silica in general industry, construction, and shipyard workplaces 
across the country. Accordingly, the rule establishes requirements for 
employers in every State to protect their employees from the risks of 
exposure to respirable crystalline silica. In States without OSHA-
approved State plans, Congress expressly provides for OSHA standards to 
preempt State occupational safety and health standards in areas 
addressed by the Federal standards. In these States, this rule limits 
State policy options in the same manner as every standard promulgated 
by the Agency. In States with OSHA-approved State plans, this rule does 
not significantly limit State policy options. Any special workplace 
problems or conditions in a State with an OSHA-approved State plan may 
be dealt with by its State standard, provided the standard is at least 
as effective as this rule.

X. State-Plan States

    When Federal OSHA promulgates a new standard or a more stringent 
amendment to an existing standard, the 28 States and U.S. territories 
with their own OSHA-approved occupational safety and health plans 
(``State-Plan States'') must revise their standards to reflect the new 
standard or amendment. The State standard must be at least as effective 
as the Federal standard or amendment, and must be promulgated within 
six months of the publication date of the final Federal rule (29 U.S.C. 
667(c)(2); 29 CFR 1953.5(a)).
    A State-Plan State may demonstrate that a standard change is 
unnecessary because the State standard is already the same as or at 
least as effective as the new or amended Federal standard. In order to 
avoid delays in worker protection, the effective date of the State 
standard and any of its delayed provisions must be the date of State 
promulgation or the Federal effective date, whichever is later. The 
Assistant Secretary may permit a longer time period if the State timely 
demonstrates that good cause exists for extending the time limitation 
(29 CFR 1953.5(a)). Of the 28 States and territories with OSHA-approved 
State plans, 22 cover public and private-sector employees: Alaska, 
Arizona, California, Hawaii, Indiana, Iowa, Kentucky, Maryland, 
Michigan, Minnesota, Nevada, New Mexico, North Carolina, Oregon, Puerto 
Rico, South Carolina, Tennessee, Utah, Vermont, Virginia, Washington, 
and Wyoming. Six States and territories cover only public-sector 
employees: Connecticut, Illinois, Maine, New Jersey, New York, and the 
Virgin Islands.
    This respirable crystalline silica rule applies to general 
industry, construction, and maritime, and imposes additional or more 
stringent requirements as compared to the existing permissible exposure 
limits for respirable crystalline silica. This rule requires that all 
State-Plan States revise their general industry and construction 
standards appropriately within six months of the date of this notice. 
In addition, State plans that cover private sector maritime employment 
or have public employees working in the maritime industry covered by 
this standard would be required to adopt comparable provisions to their 
maritime standards within six months of publication of the final rule.

XI. Unfunded Mandates

    OSHA reviewed this rule according to the Unfunded Mandates Reform 
Act of 1995 (UMRA) (2 U.S.C. 1501 et seq.) and Executive Order 13132 
(64 FR 43255 (8/

[[Page 16698]]

10/1999)). Under Section 202 of the UMRA (2 U.S.C. 1532), an agency 
must prepare a written ``qualitative and quantitative assessment'' of 
any regulation creating a mandate that ``may result in the expenditure 
by the State, local, and tribal governments, in the aggregate, or by 
the private sector, of $100,000,000 or more'' in any one year before 
promulgating a final rule. OSHA's rule does not place a mandate on 
State or local governments, for purposes of the UMRA, because OSHA 
cannot enforce its regulations or standards on State or local 
governments (29 U.S.C. 652(5)). Under voluntary agreements with OSHA, 
some States require public sector entities to comply with State 
standards, and these agreements specify that these State standards must 
be at least as protective as OSHA standards. The Occupational Safety 
and Health Act (29 U.S.C. 651 et seq.) does not cover tribal 
governments in the performance of traditional governmental functions, 
though it does cover tribal governments when they engage in commercial 
activity. However, the rule would not require tribal governments to 
expend, in the aggregate, $100,000,000 or more in any one year for 
their commercial activities. As noted below, OSHA also reviewed this 
rule in accordance with Executive Order 13175 on Consultation and 
Coordination with Indian Tribal Governments (65 FR 67249 (11/9/2000)), 
and determined that it does not have ``tribal implications'' as defined 
in that Executive Order.
    OSHA concludes that the final rule would impose a Federal mandate 
on the private sector in excess of $100,000,000 in expenditures in any 
one year, as documented in the Final Economic Analysis (FEA) (see 
Section VII, Summary of the Final Economic Analysis and Final 
Regulatory Flexibility Analysis). However, the final rule does not 
trigger the requirements of UMRA based on its impact on State, local, 
or tribal governments. The FEA constitutes the written statement 
containing a qualitative and quantitative assessment of these 
anticipated costs and benefits required under Section 202(a) of the 
UMRA (2 U.S.C. 1532(a)).

XII. Protecting Children From Environmental Health and Safety Risks

    Executive Order 13045 requires that Federal agencies submitting 
covered regulatory actions to the Office of Management and Budget's 
Office of Information and Regulatory Affairs (OIRA) for review pursuant 
to Executive Order 12866 must provide OIRA with (1) an evaluation of 
the environmental health or safety effects that the planned regulation 
may have on children, and (2) an explanation of why the planned 
regulation is preferable to other potentially effective and reasonably 
feasible alternatives considered by the agency (62 FR 19885 (4/23/
1997)). Executive Order 13045 defines ``covered regulatory actions'' as 
rules that may (1) be economically significant under Executive Order 
12866 (i.e., a rulemaking that has an annual effect on the economy of 
$100 million or more, or would adversely effect in a material way the 
economy, a sector of the economy, productivity, competition, jobs, the 
environment, public health or safety, or State, local, or tribal 
governments or communities), and (2) concern an environmental health 
risk or safety risk that an agency has reason to believe may 
disproportionately affect children. In this context, the term 
``environmental health risks and safety risks'' means risks to health 
or safety that are attributable to products or substances that children 
are likely to come in contact with or ingest (e.g., through air, food, 
water, soil, product use).
    The respirable crystalline silica rule is economically significant 
under Executive Order 12866 (see Section VII, Summary of the Final 
Economic Analysis and Final Regulatory Flexibility Analysis). However, 
after reviewing the rule, OSHA has determined that the rule would not 
impose environmental health or safety risks to children as set forth in 
Executive Order 13045. The rule would require employers to limit 
employee exposure to respirable crystalline silica and take other 
precautions to protect employees from adverse health effects associated 
with exposure to respirable crystalline silica. OSHA is not aware of 
any studies showing that exposure to respirable crystalline silica 
disproportionately affects children, that there are a significant 
number of employees under 18 years of age who may be exposed to 
respirable crystalline silica, or that employees of that age are 
disproportionately affected by such exposure.
    A few commenters expressed concerns about exposure of children to 
respirable crystalline silica through their parents' contaminated work 
clothing (e.g., Document ID 4204, pp. 73-74). The American Federation 
of Labor and Congress of Industrial Organizations concluded that 
maintaining OSHA's longstanding hierarchy of controls in the final rule 
would prevent silica dust from being carried home on work clothing 
better than would a rule that relies solely on respirators to protect 
workers (Document ID 4204, pp. 64-65, 72-74). OSHA agrees, and finds 
that the final rule's primary reliance on engineering and work practice 
controls to protect workers will result in greater protection to 
children than either the prior permissible exposure limit for 
respirable crystalline silica or a rule that places primary reliance on 
respiratory protection.
    Because OSHA does not believe that the health risks of respirable 
crystalline silica have a disproportionate impact on children, OSHA 
concludes the respirable crystalline silica rule does not constitute a 
covered regulatory action as defined by Executive Order 13045. To the 
extent children are exposed to respirable crystalline silica either as 
employees or at home as a result of family members' workplace 
exposures, the final rule offers greater protection than did the 
previous permissible exposure limits.

XIII. Consultation and Coordination With Indian Tribal Governments

    OSHA reviewed this final rule in accordance with Executive Order 
13175 on Consultation and Coordination with Indian Tribal Governments 
(65 FR 67249 (11/9/2000)), and determined that it does not have 
``tribal implications'' as defined in that Executive Order. The 
Occupational Safety and Health Act (29 U.S.C. 651 et seq.) does not 
cover tribal governments in the performance of traditional governmental 
functions, so the rule will not have substantial direct effects on one 
or more Indian tribes in their sovereign capacity, on the relationship 
between the Federal government and Indian tribes, or on the 
distribution of power and responsibilities between the Federal 
government and Indian tribes. On the other hand, employees in 
commercial businesses owned by tribes or tribal members will receive 
the same protections and benefits of the standard as all other covered 
employees.

XIV. Environmental Impacts

Introduction

    OSHA has reviewed the final rule according to the National 
Environmental Policy Act (NEPA) of 1969 (42 U.S.C. 4321 et seq.), the 
regulations of the Council on Environmental Quality (40 CFR part 1500 
et seq.), and the Department of Labor's NEPA procedures (29 CFR part 
11). The Agency has determined that the final rule will have no 
significant impact on air, water, or soil quality; plant or animal 
life; the use of land; or other aspects of the external environment. 
Therefore, OSHA concludes that the final standard will

[[Page 16699]]

have no significant environmental impacts. This conclusion reaffirms 
the conclusions set forth in the Preliminary Economic Analysis (PEA).
    To reach this conclusion, OSHA examined comments received about the 
potential environmental impacts posed by the final rule. Comments 
addressed two main issues: (1) Potential water runoff from construction 
tasks; and (2) costs associated with federal, state, and local 
environmental permits employers could be required to obtain as a result 
of the final rule. There were no specific comments regarding soil 
quality, plant or animal life, or land use. This section first lays out 
OSHA's preliminary conclusions regarding environmental impacts and then 
shows why the best available evidence in the rulemaking record 
reaffirms those conclusions. SBREFA and Conclusions Contained in the 
PEA
    Pursuant to the recommendations from the Small Business Advocacy 
Review Panel, the Agency investigated potential environmental impacts 
and articulated its findings in the PEA. As noted in the SBREFA report 
(Document ID 0937, p. 77), the Panel requested that OSHA clarify how 
its silica rulemaking was related to designating silica-containing 
materials as hazardous wastes. In the PEA, OSHA explained that it did 
not believe silica wastes are classified as hazardous wastes for 
purposes of the Environmental Protection Agency (EPA) (Document ID 
1720, p. IX-68). And the contents of OSHA's final rule on silica have 
no direct bearing on whether silica waste is classified as hazardous 
for EPA purposes.
    In addition, some Small Entity Representatives (SERs) raised the 
possibility that the use of wet methods to limit silica exposures in 
some areas could violate EPA rules with respect to suspended solids in 
runoff unless provisions are made for recycling or settling the 
suspended solids out of the water. The SBAR Panel recommended that OSHA 
investigate this issue, add appropriate costs if necessary, and solicit 
comment. In response, the Agency identified six construction tasks 
where wet methods were utilized and found negligible costs related to 
controlling excess water because the amount of water used to control 
silica dust was minimal and typically did not produce runoff. OSHA's 
estimate of the potential environmental impact of each of these six 
equipment types was summarized in the PEA as follows:
     Stationary masonry saws: Most stationary saws come 
equipped with a water basin that typically holds several gallons of 
water and a pump for recycling water for wet cutting. The water is 
recirculated and, thus, not continually discharged. When emptied, the 
amount of water is not sufficient to produce a runoff.
     Hand-held masonry saws: Large quantities of water 
typically are not required in order to control dust. With these saws, 
water is supplied from a small capacity water tank. Any slurry residue 
after cutting could be dealt with by sweeping or vacuuming.
     Walk-behind and other large concrete saws: Larger concrete 
saws are equipped with a tank to supply water to the blade while 
cutting. These saws leave a slurry residue, but do not require so much 
water as to create a runoff.
     Walk-behind concrete grinders and millers: Some tools are 
equipped with a water-feed system. In these, a water line from a tank, 
a garden hose, or other water supply leads to the grinding head and 
delivers water to spray or flood the cutting tool and/or the work 
surface. When an automatic water feed is not available, a helper can 
apply water directly to the cutting surface. While such wet methods 
might generate enough water to create a runoff, these grinding and 
milling activities are typically done during the finishing stages of 
structure construction (e.g., parking garages) and are often performed 
inside the structure. Thus, direct discharges to storm drains or 
surface waters are unlikely.
     Asphalt millers for pavement resurfacing: A typical 
asphalt milling machine has a built-in reservoir from which water is 
applied to the cutting drum. The amount of water used, however, is 
insufficient to produce a runoff.
     Impact drillers/pavement breakers: Water for dust 
suppression can be applied manually or by using a semi-automated water-
feed device. In the simplest method for suppressing dust, a dedicated 
helper directs a constant spray of mist at the impact point while 
another worker operates the jackhammer. The helper can use a hose with 
a garden-style spray nozzle to maintain a steady and carefully directed 
mist at the impact point where material is broken and crushed. 
Jackhammers retrofitted with a focused water mist aimed at the tip of 
the blade offer a dramatic decrease in silica exposure. Although water-
fed jackhammers are not commercially available, it is neither expensive 
nor difficult to retrofit equipment. Studies suggest that a water flow 
rate of 1/8 to 1/4 gallon per minute is best for silica dust control. 
At this rate, about 7.5 to 15 gallons of water per hour would be 
applied to (i.e., sprayed on) the work area. It is unclear whether this 
quantity of water applied to a moveable work area at a constant rate 
would produce a runoff. If the work were in sufficient proximity to a 
storm drain or surface water, the contractor might need to use a simple 
barrier to prevent the water from entering the drain, or otherwise 
filter it. Because the volume of water is relatively small, the costs 
for such barriers are likely insubstantial and would typically overlap 
with the contractor's existing obligations for a site-control plan to 
prevent unwanted runoff from other causes.
    In the PEA, OSHA found that employers typically have pre-existing 
obligations to limit runoff of solid waste, such as from rainfall, into 
storm drains. The Agency preliminarily concluded that: (1) The use of 
wet methods for certain construction tasks would not cause significant 
environmental problems from water runoff; and (2) employers should be 
able to comply with non-OSHA environmental regulations because runoff 
from wet methods can be easily controlled. As explained below, in light 
of the best available evidence contained in the record, OSHA reaffirms 
its preliminary conclusions.

Potential Water Runoff From Construction Tasks

    While the Agency did not receive any comments directly addressing 
the PEA's discussion of environmental impacts, it did receive several 
comments on the water runoff issue. Most of the concerns expressed 
related to construction work, although a few comments came from 
entities in general industry. The construction and general industry 
commenters that addressed the issue of water runoff from the use of wet 
methods to comply with the final PEL included James Hardie Building 
Products, Inc.; the Unified Abrasives Manufacturers' Association; 
American Road & Transportation Builders Association; the General 
Contractors Association of New York; the Masonry & Concrete Saw 
Manufacturers Institute; and the Fertilizer Institute. None of the 
commenters to raise this issue provided any evidence to establish that 
runoff created by wet methods would actually create a problem (Document 
ID 2322, Attachment G, p. 14; 2243, p. 2; 2245, p. 4; 2314, p. 2; 2316, 
Attachment 1, pp. 2-3; 2101, pp. 6-7, 11-12). For example, one 
commenter, the Construction Industry Safety Coalition, advanced a 
theoretical argument that wet methods would either: (a) Require 
``tremendous'' amounts of water; or (b) fail to effectively control 
silica. It stated:


[[Page 16700]]


    For employers using wet methods, even attempting to meet this 
``no visible dust'' standard will require a tremendous amount of 
water--many studies discussed in the technological feasibility 
analysis certainly support this notion. Such large amounts of water 
run counter to OSHA's contractor's assessment that ``minimal'' water 
should be used to avoid environmental contamination issues. The 
Agency contends that construction employers can mitigate any 
environmental concerns by utilizing as little water as possible to 
prevent accumulations from occurring or potentially damaging 
residential or commercial buildings. Even if utilizing only a little 
water will effectively reduce exposures to below the proposed PEL, 
the CISC has significant concerns that it will prevent all visible 
dust from being emitted (Document ID 2320, Attachment 1, pp. 9-10).

    In light of the discussion set forth in Chapter VI of the FEA, 
Technological Feasibility, and evidence in the record, OSHA's 
preliminary findings regarding water runoff are affirmed. The Agency 
concludes that the comments it received expressing concerns about the 
runoff issue are unsubstantiated and theoretical and do not provide a 
sufficient justification for OSHA to alter its preliminary conclusions. 
As discussed in the Technological Feasibility section, OSHA finds that 
appropriate wet methods will typically require only limited application 
of water, possibly as little as a mist. In such conditions, the water 
will evaporate before collecting into a body of water. Where a greater 
water flow is necessary to suppress airborne silica, the runoff, rather 
than forming a free-flowing stream, will typically consolidate into 
slurry. In addition, because employers want to keep nearby structures 
and materials dry, they will typically use as little water as 
necessary.
    OSHA finds support for these findings in the hearing testimony 
compilation assembled by the Building and Construction Trades 
Department. That evidence demonstrates the practical reality that water 
runoff from construction tasks is insignificant (Document ID 4223, pp. 
28-30). Indeed, Deven Johnson, of the Operative Plasterers' and Cement 
Masons' International Association, stated that in her years of 
experience in using wet methods to control relatively dusty situations 
involving demolition, she had never had a problem with runoff-related 
issues. She indicated that runoff tends to create a slurry, which is 
easily vacuumed up (Document ID 3581, pp. 1695-1696). Gary Fore, a 
consultant and former Vice President for the American National Asphalt 
Pavement Association, likewise said that runoff was never a problem. He 
confirmed the PEA's preliminary conclusion for asphalt milling 
operations. While there may be a substantial amount of water used in 
the course of a day, it is applied as an aerosol. Further, although the 
pavement surface may be temporarily moist, it does not produce runoff 
from the construction site (Document ID 3583, p. 2209). Finally, Donald 
Hulk, Safety Director for Manafort, a construction contractor, 
testified that contrary to hypothetical assertions about potential 
runoff issues, his company did not find managing potential runoff from 
wet methods to be a problem. His reasoning confirmed the PEA's finding 
that the amount of water required for typical silica-containing dust 
suppression will not create substantial runoff. Moreover, he testified 
that in the case of demolition related to roadway construction, excess 
water is typically absorbed into demolition debris or evaporates--which 
is aided by the fact that most construction activity occurs during the 
warmer parts of the year (Document ID 3583, Tr. 2384-2385).
    Certain industries voiced water runoff concerns specific to their 
workplaces. For example, the fertilizer industry stated its 
apprehension about OSHA's ``preference'' for wet methods to control 
silica exposure and indicated that such methods would be potentially 
problematic from an environmental standpoint at its facilities 
(Document ID 2101, pp. 6-7, 11-12). OSHA finds the fertilizer 
industry's concern misplaced because the final standard does not 
require the use of wet methods in general industry. Additionally, as 
discussed in Chapter III, the Agency estimates that exposures to 
respirable crystalline silica in the fertilizer industry are 
sufficiently low that most fertilizer-related manufacturing industries 
will not be affected by the final standard; the mixing-only fertilizer 
industry, NAICS 325314, was the only one judged to be affected.
    The coal-fired electric industry also raised the issue of water 
runoff in its industry. The Edison Electric Institute and Alabama Power 
Company indicated a potential for conflict between an EPA rulemaking 
regarding ash ponds at the site of coal-fired electric utilities and 
this rulemaking (Document ID 2357, pp. 28-29; 2185, Attachment 1, p. 
11). OSHA considered this concern, but has concluded that this will not 
be a problem in practice. The commenters never explained how the wet 
methods that might be required in Table 1 for construction activities 
(e.g., cutting concrete for transmission and distribution) would result 
in water flowing into fly ash ponds. In any event, the Agency has found 
that the proper use of wet methods will not result in significant 
runoff issues for any of the industries covered by the standard.\128\
---------------------------------------------------------------------------

    \128\ Alabama Power also referred to problems with environmental 
permits, but did not specify to which environmental permits they 
were referring. Permit issues are addressed later in this section.
---------------------------------------------------------------------------

Air Quality/Permit Concerns

    Regulations that will reduce the atmospheric concentration of 
respirable crystalline silica in the air within industrial and other 
facilities and workplaces have the potential to affect, either 
positively or negatively, the amount of respirable crystalline silica 
emitted by these sources into the ambient (external) environment. In 
most cases, the change will be small. As discussed in Chapter V of the 
FEA, Costs of Compliance, most ventilation is needed to reach the 
preceding PEL rather than the new PEL. The extent to which the 
reduction in the PEL--and, hence, occupational exposures--under the 
OSHA standard will impact air quality depends on how employers handle 
the increased volume of respirable crystalline silica captured by the 
relevant control technologies. Taking into account the measures 
employers are already using to comply with the existing silica PEL, and 
the fact that the baghouses employers are already using capture at 
least 99 percent of silica emissions (Document ID 3641, p. VII-19), 
OSHA concludes that the final rule will not have a significant impact 
on air quality
    A number of commenters raised concerns that the final rule would 
create an onerous and cost-increasing administrative burden because it 
would necessitate obtaining EPA environmental permits, notably with 
regard to air quality regulations and related permits and process 
approvals at the state and local level. The concern was not an adverse 
environmental impact, per se, but rather the burden of complying with 
existing environmental rules in the context of the new OSHA standard 
(e.g., Document ID 2291, Attachment 1, p. 12; 2379, Appendix 1, p. 14; 
2380, Attachment 2, p. 19; 2317, pp. 2-3). OSHA's response to these 
cost concerns is addressed in Chapter V of the FEA in the section on 
general industry engineering control costs.
    A prime concern voiced by the commenters was having to comply with 
OSHA compliance deadlines while simultaneously meeting deadlines under 
applicable air quality permitting regulations.
    For example, the Asphalt Roofing Manufacturers Association (ARMA) 
raised the issue of EPA permits related to changes in ventilation 
systems.


[[Page 16701]]


. . . the proposal appears to completely disregard environmental 
permitting requirements, which will present a significant time 
demand in almost every case because the standard will require 
increased dust collection, and releases to outside air will trigger 
air pollution limitations and permitting requirements for both State 
and or Federal agencies. Recent experience of ARMA members relating 
to implementation of the new National Ambient Air Quality Standards 
(NAAQS) for particulate matter (PM2.5) reveals that, even 
in the case of minor facility modifications which emit particulate 
matter, authorization to construct or modify a control device can 
take more than a year to obtain. Even longer permitting times will 
be experienced in cases requiring complex modeling of nearby 
sources, or State or Federal approval of modeling methods and 
protocol inputs. These factors could further delay the issuance of 
permits by an additional twelve months, assuming the facility is 
able to develop a passing model. If the model does not pass, further 
modeling and review by permitting agencies, or additional emissions 
abatement, may be required to obtain the permits, extending still 
further this step in the process (Document ID 2291, Attachment 1, p. 
12).

    As the Agency explains in the Summary & Explanation section of the 
preamble dealing with paragraph (j), dates, the final rule's effective 
and enforcement dates have been tailored to allow a sufficient period 
of time for employers to meet requirements for approval by other 
regulatory agencies. (A discussion of various state permitting times 
can be found in ``Examples of State Environmental Agency Permit 
Turnaround Times,'' ERG, 2015.) The Agency believes providing longer 
compliance deadlines should address the primary concerns expressed by 
commenters regarding the time necessary to obtain any required 
environmental permit approvals. Ultimately, as discussed in the Summary 
and Explanation, cases that are unusually problematic can be addressed 
through OSHA's enforcement discretion if the employer can show that it 
has made good faith efforts to implement engineering controls, but has 
been unable to implement such controls due to the time needed for 
environmental permitting.
    Some industries raised permit concerns unique to their operations. 
The Association of American Railroads and American Short Line and 
Regional Railroad Association stated that it foresaw a need for a 
permit under the Clean Water Act if a ballast was sprayed with a 
chemical, which, through run off or by another means, reached a body of 
water (Document ID 2366, p. 7).
    OSHA considers the railroad industry's concern about the threat of 
significant water contamination from chemical dust suppressant 
speculative because of the limited amount of water potentially used. 
Consequently, the Agency does not foresee a significant environmental 
impact. Additionally, no current OSHA standard governs the use of 
chemical dust suppressants. While some state or local governments may 
require a permit, it is not clear this would pose a new issue for the 
railroads, as OSHA believes it is likely that they already have to deal 
with such issues in the context of runoff from deicing chemicals, as 
well as oil and metal particles from normal operations. OSHA notes, 
however, that the analysis in the railroad section of Chapter IV of the 
FEA, Technological Feasibility, discusses chemical suppressants merely 
as a possibility for reducing exposures, but it is not ultimately 
identified as necessary to enable employers in the industry to meet the 
PEL of 50 [mu]g/m\3\. Accordingly, the FEA's cost analysis for the 
railroad industry does not include chemical suppressants, but assumes 
the industry will use wet methods to reduce exposures, and estimates 
the costs accordingly. To the extent chemical dust suppressants are 
more cost-effective than water, the FEA has overestimated the cost to 
the industry. And to the extent suppressants pose an environmental air 
quality permitting issue, OSHA notes that suppressants are not required 
under the final rule and is not including relevant permitting costs in 
its analysis.
    The Shipbuilders Council of America (SCA) stated that if the final 
silica rule altered blasting technologies and/or facility equipment, 
the data currently used for shipyard permits in certain states (e.g., 
state air and water permits) would be invalid, necessitating permit and 
plan updates and creating additional costs for the industry (Document 
ID 2255, p. 2). The final rule does not specify engineering control 
changes in this area; nor does the Agency believe the lower PEL will 
require a change in engineering controls for abrasive blasting, 
relative to current standards. As laid out in Chapter V in the FEA, 
employers complying with the hierarchy of controls under the existing 
silica PEL and ventilation standards will already be using engineering 
controls to limit exposures. OSHA has found that the only additional 
feasible engineering controls employers in shipyards can implement to 
reduce exposures is the use of HEPA vacuums (in lieu of dry sweeping). 
Implementation of this control will reduce potential environmental 
problems because the use of HEPA vacuums raises less dust than dry 
sweeping.

Positive Environmental Effects

    Based on its review of the record, OSHA concludes that the final 
rule will potentially have a positive environmental impact. At least 
one industry commenter, in the context of the hydraulic fracturing 
industry, suggested that its technology, the adoption of which would 
presumably be hastened by the promulgation and enforcement of the final 
rule, would reduce potential environmental impacts (Document ID 3589, 
Tr. 4140). In a similar vein, as discussed in both Chapters IV and V of 
the FEA, the final standard actually helps construction employers' 
reduce fugitive and co-generated dust, aiding in their compliance with 
environmental standards related to the dust. (The issue of controlling 
fugitive dust overlaps with the issue of existing employer obligations 
to minimize the runoff of solid waste into public water, discussed 
previously in this chapter, as well as the general expectation that 
employers clean up their work sites after their work is completed, as 
discussed in Chapter V).

Conclusion

    As a result of this review, OSHA has reaffirmed its conclusions in 
the PEA, that the silica final rule will have no significant impact on 
air, water, or soil quality; plant or animal life; the use of land; or 
aspects of the external environment. It finds that the final standard 
is in compliance with NEPA and will have no significant environmental 
impact.

XV. Summary and Explanation of the Standards

    OSHA proposed two standards for occupational exposure to respirable 
crystalline silica--one for general industry and maritime and a second 
for construction. Both proposed standards were structured according to 
OSHA's traditional approach, including separate provisions for a 
permissible exposure limit (PEL), exposure assessments, and methods of 
compliance, which includes a requirement to follow the hierarchy of 
controls. The methods of compliance provision in the proposed 
construction standard included Table 1, which specified engineering 
controls, work practices, and respiratory protection for common 
construction operations (now referred to as tasks). Construction 
employers who would have chosen to fully implement engineering 
controls, work practices, and respirators for a task in proposed Table 
1 would have been exempted from conducting exposure assessments for 
employees conducting

[[Page 16702]]

that task, but would have been required to comply with the PEL.
    The structure of the final standard for general industry and 
maritime remains generally consistent with other OSHA health standards. 
The most significant structural change from the proposed general 
industry and maritime standard is that ``cleaning methods,'' which was 
under the Methods of Compliance paragraph, is now a separate paragraph 
called Housekeeping. The same change regarding Housekeeping was made to 
the standard for construction. In addition both standards include a 
requirement for a written exposure control plan, which is included 
under the Methods of Compliance paragraph in the standard for general 
industry and maritime but as a separate paragraph in the standard for 
construction. Most importantly, the structure for the construction 
standard is significantly different from OSHA's traditional approach to 
address stakeholder concerns about compliance in the construction 
industry.
    Many stakeholders thought that construction employers who fully and 
properly implement the engineering controls, work practices, and 
respiratory protection specified in Table 1 should be considered to be 
in compliance with the PEL. As reflected in paragraph (c) of the 
standard for construction (which includes Table 1), and as discussed in 
more detail in the summary and explanation, OSHA agrees that 
construction employers who fully and properly implement the engineering 
controls, work practices, and respiratory protection for a task on 
Table 1 do not have to demonstrate compliance with the PEL for that 
task, because these controls provide a level of protection equivalent 
to that provided by the alternative approach that includes the 50 
[micro]g/m\3\ PEL.
    OSHA also received many comments about the challenges of conducting 
exposure assessments in the construction industry. OSHA expects that 
because of these challenges most construction employers will follow 
Table 1. Therefore, OSHA made major structural changes to the standard 
for construction to emphasize Table 1 in paragraph (c) for employers 
who choose to follow that approach. Paragraph (d) of the standard for 
construction provides alternative exposure control methods for 
construction employers who choose not to follow Table 1 or who perform 
tasks that are not included in Table 1 (e.g., abrasive blasting and 
underground construction (tunnel boring)). Paragraph (d) of the 
standard for construction contains requirements, including the PEL, 
exposure assessments, and methods of compliance, that follow OSHA's 
traditional approach.
    Construction employers who choose to follow Table 1 of paragraph 
(c) are exempt from following paragraph (d) but must comply with 
provisions in all other paragraphs of the standard for construction. On 
the other hand, construction employers who follow the alternate 
exposure control methods in paragraph (d) are exempt from following the 
provisions in paragraph (c) but must comply with the provisions in all 
other paragraphs of the standard for construction.
    Although the structure of the standard for general industry and 
maritime differs from the structure of the standard for construction, 
many of the requirements are the same or similar in both standards. 
Therefore the summary and explanation is organized according to the 
main requirements of the standards. It includes paragraph references to 
the standard for general industry and maritime, followed by paragraph 
references for the standard for construction. The summary and 
explanation uses the term ``rule'' when referring to both standards. 
Generally, when the summary and explanation refers to the term 
``rule,'' it is referring to the final rule. To avoid confusion, the 
term ``final rule'' is sometimes used when making a comparison to or 
clarifying a change from the proposed rule.

Scope and Application

    Separate standards for general industry/maritime and construction. 
OSHA proposed two separate standards addressing occupational exposure 
to respirable crystalline silica: one for exposures in general industry 
and maritime, and another for exposures in the construction industry. 
The proposed standards were intended to provide equivalent protection 
for workers while accounting for the different work activities, 
anticipated exposures, and other conditions in these sectors.
    Commenters representing construction employers, labor unions, and 
governmental entities noted the intrinsic differences between 
construction and other industries and were generally supportive of 
OSHA's decision to propose one standard for general industry and 
maritime and another for construction (e.g., Document ID 1955, p. 2; 
2116, p. 40; 2166, p. 3; 2181, p. 4; 2262, p. 14; 2318, p. 13; 2371, p. 
5; 3403, p. 3). However, some stakeholders expressed concerns about 
differentiation among industries.
    The Association of Occupational and Environmental Clinics opposed 
applying occupational health protection measures differently (Document 
ID 3399, p. 4). Edison Electric Institute (EEI) argued that differences 
in the standards may create confusion, administrative burden, and 
ambiguity, and could ultimately frustrate good-faith compliance 
efforts. EEI suggested that the easiest solution would be for OSHA to 
have ``a single regulation applicable to the electric utility industry, 
rather than separate General Industry and Construction requirements'' 
(Document ID 2357, p. 17).
    Commenters representing utility providers, surface mineral mining, 
rock crushing, railroad operations, and truck distribution expressed 
concerns about separate standards creating uncertainty about which 
requirements would apply to various activities (Document ID 2101, p. 3; 
2185, pp. 4-5; 2318, p. 13; 2357, p. 4; 2366, p. 3; 3492, p. 2). 
Southern Company cited the installation of new power delivery lines 
versus the repair or maintenance of existing power delivery lines as an 
example, indicating that once a concrete pole is in the ground the 
process of mounting hardware is exactly the same, but the applicable 
standard may be different (Document ID 2185, p. 4).
    The International Brotherhood of Teamsters (IBT) also expressed 
concerns about work activities where it may not be clear whether the 
general industry or construction standard applies. IBT noted that 
ready-mix concrete truck drivers frequently travel to more than one 
work location and may work at many different construction sites on any 
given day. These workers are typically covered by the general industry 
standard; however, they may work at construction sites and perform 
certain tasks that could be considered construction work (Document ID 
2318, p. 13).
    Several commenters requested that OSHA develop a table listing 
specified exposure control methods for general industry, comparable to 
proposed Table 1 for construction, or that OSHA add general industry 
tasks to Table 1 (Document ID 2116, Attachment 1, p. 3; 2212, p. 2; 
2244, p. 4; 2339, p. 8; 2357, p. 1). The American Society of Safety 
Engineers requested that Table 1 ``be considered for the general 
industry/maritime standard for commonly performed tasks involving high 
levels of silica exposure'' (Document ID 2339, p. 8).
    After considering the concerns raised by commenters, OSHA is 
issuing one standard that addresses occupational exposure to respirable 
crystalline silica in general industry and maritime work and another 
for construction work. As reflected primarily in paragraph (c) and

[[Page 16703]]

Table 1 of the standard for construction, the Agency finds that certain 
conditions inherent to the construction industry, such as the transient 
nature of the work, warrant alternatives to protect employees that are 
somewhat different than those that apply to general industry and 
maritime work. OSHA has long recognized a distinction between the 
construction and general industry sectors, and has issued standards 
specifically applicable to construction work under 29 CFR part 1926. 
The Agency has provided a definition of the term ``construction work'' 
at 29 CFR 1910.12(b), has explained the terms used in that definition 
at 29 CFR 1926.13, and has issued numerous interpretations over the 
years explaining the classification of activities as either general 
industry or construction work.
    In issuing separate standards for general industry/maritime and 
construction, OSHA's intent is to ensure that employees exposed to 
respirable crystalline silica in construction are, to the extent 
feasible, provided equivalent protection to that afforded employees in 
general industry and maritime. Specifically, OSHA intends that Table 1 
in paragraph (c) of the construction standard, while providing 
employers with an alternative, flexible approach to addressing exposure 
to respirable crystalline silica in construction, will provide the same 
level of protection against exposures to silica for construction 
employees as is provided to general industry and maritime employees; 
the same is true for construction employees whose employers are 
following the traditional exposure assessment and hierarchy of controls 
approach under paragraph (d) of the construction standard.
    OSHA recognizes that in some circumstances, general industry 
activities and conditions in workplaces where general industry tasks 
are performed may be indistinguishable from those found in construction 
work. In some cases, employers whose primary business is classified as 
general industry may have some employees who perform construction work, 
and employers whose primary business is classified as construction may 
have some employees who perform general industry work. Given the wide 
variety of tasks performed in the workplace, it is inevitable that 
questions will arise regarding the classification of certain 
activities, and these questions have been and will continue to be 
addressed in letters of interpretation and other guidance issued by 
OSHA. However, the distinction between sectors is generally well 
understood by both OSHA enforcement personnel and the regulated 
community, and OSHA concludes that any attempt to create exceptions or 
to provide different criteria in this final rule would not improve upon 
the current criteria but would, rather, cause confusion.
    In certain circumstances, tasks performed in a general industry 
setting may be indistinguishable from the tasks listed on Table 1, and, 
under these circumstances, OSHA intends to treat full compliance with 
the construction standard as full compliance with the general industry/
maritime standard. Accordingly, OSHA has revised the scope provision 
(i.e., paragraph (a)) in the general industry and maritime standard by 
adding paragraph (a)(3) to permit employers to follow the construction 
standard rather than the general industry and maritime standard when 
the general industry/maritime task performed is indistinguishable from 
a construction task listed on Table 1 in paragraph (c) of the 
construction standard, and the task will not be performed regularly in 
the same environment and conditions.
    These indistinguishable tasks should not be merely parallel or 
complementary to or occurring at the same time and place as the 
construction tasks listed on Table 1, but rather should be of the same 
nature and type as those construction tasks. OSHA anticipates that the 
option in paragraph (a)(3) will apply primarily to maintenance and 
repair tasks performed in general industry or maritime settings. For 
example, an employee using a portable masonry saw to cut brick to patch 
a section of an existing brick wall, which is typically maintenance, 
would require tools and controls that are the same as those of an 
employee cutting brick while building a new brick wall, which is 
construction work. In performing this task, the employer could follow 
the construction standard, including paragraph (c)(1)(ii) of Table 1, 
rather than the general industry and maritime standard. Similarly, the 
installation of new power delivery lines is considered a construction 
activity, while the repair or maintenance of existing power delivery 
lines is considered a general industry task, even though a handheld 
drill may be used to drill a hole in concrete during both activities. 
In this situation, if the employer complies with the entry on Table 1 
for handheld and stand-mounted drills (paragraph (c)(1)(vii) of the 
construction standard), in addition to all other applicable provisions 
of the construction standard (e.g., paragraph (g), Written exposure 
control plan), the employer would not be obligated under the general 
industry and maritime standard to perform an exposure assessment for 
the employee(s) engaged in the drilling task, or be subject to citation 
for failure to meet the permissible exposure limit (PEL); instead, the 
employer would have the same accommodation that Table 1 in paragraph 
(c) of the construction standard affords a construction employer doing 
that task and following paragraph (c). However, in the event that the 
employer fails to fully comply with the construction standard by, for 
example, failing to fully and properly implement the controls on Table 
1 or to fully establish and implement a written exposure control plan 
(e.g., by not designating a competent person to implement the plan), 
the employer would be subject to the general industry and maritime 
standard and could be cited for not having performed an exposure 
assessment or not having achieved the PEL with respect to the 
employee(s) engaged in that task.
    Paragraph (a)(3)(ii) of the general industry and maritime standard 
provides that, in order for the employer to be able to avail itself of 
the option to follow the construction standard, the task must not be 
performed regularly in the same environment and conditions. For 
example, an employer that performs sanding or cutting of concrete 
blocks in a concrete block manufacturing plant may not follow the 
construction standard, because the task is performed regularly in the 
same environment and conditions. Likewise, an employer whose business 
includes chipping out concrete from inside the drums of ready-mixed 
concrete trucks using pneumatic chipping tools may not follow the 
construction standard, because that task will be regularly performed in 
a relatively stable and predictable environment that would not require 
the accommodation of Table 1, which is intended in part to accommodate 
situations where the tasks will be performed in different environments 
and conditions.
    Regarding comments that exposure controls should be specified in 
the general industry and maritime standard in a manner similar to that 
of Table 1 for construction tasks, OSHA concludes that, for most 
general industry operations, it is not possible to develop a 
specification that would broadly apply to facilities that vary widely 
in size, process design, and complexity while being specific enough to 
provide reasonably objective criteria against which to judge compliance 
with the standard. Unlike for construction tasks, the rulemaking record 
does not provide sufficient information for OSHA to account for the 
wide variety of potential

[[Page 16704]]

tasks across the range of manufacturing and other general industry 
work. In manufacturing industries such as foundries and pottery 
production, local exhaust specifications must be custom designed for 
each establishment considering its manufacturing processes, equipment, 
and layout. Based on its over forty years of experience in enforcing 
occupational safety and health standards, OSHA concludes that in 
general industry and maritime, employee protection is best provided 
through a performance-oriented standard that permits employers to 
implement engineering controls and work practices that best fit their 
situation. In contrast, the task-based operations performed in 
construction are uniquely suited to a specification approach since the 
same equipment and dust controls are generally used regardless of the 
nature of the construction project, making specification of an 
effective dust control approach possible.
    Agriculture. The proposed rule did not cover agricultural employers 
due to limited data on exposures and control measures in the 
agriculture sector. OSHA's authority is also restricted in this area; 
since 1976, an annual rider in the Agency's Congressional 
appropriations bill has limited OSHA's use of funds with respect to 
farming operations that employ fewer than ten employees (Consolidated 
Appropriations Act, 1976, 94, 90 Stat. 1420, 1421 (1976) (and 
subsequent appropriations acts)). The Agency requested information on 
agricultural operations that involve respirable crystalline silica 
exposures in the Notice of Proposed Rulemaking (NPRM), as well as 
information related to the development of respirable crystalline 
silica-related adverse health effects and diseases among employees in 
the agricultural sector (78 FR 56274, 56288 (9/12/13). OSHA did not 
receive information that would support coverage of agricultural 
operations. Therefore, agriculture employers and operations are not 
covered by the rule, as specified in paragraph (a)(1)(ii) of the 
general industry and maritime standard.
    Mine Safety and Health Administration (MSHA) jurisdictional 
concerns. The Fertilizer Institute (TFI) and Fann Contracting, Inc. 
requested that OSHA clarify the jurisdictional limits of the silica 
rule in light of OSHA's memorandum of understanding (MOU) with MSHA 
(Document ID 2101, p. 3; 2116, p. 31) (citing Interagency Agreement 
Between the Mine Safety and Health Administration U.S. Department of 
Labor and the Occupational Safety and Health Administration U.S. 
Department of Labor). The MOU, which has been in effect since March 29, 
1979 (Document ID 2101, p. 3), delineates certain areas of respective 
authority, sets forth factors regarding determinations relating to 
convenience of administration, provides a procedure for determining 
general jurisdictional questions, and provides for coordination between 
MSHA and OSHA in all areas of mutual interest. The respirable 
crystalline silica rule in no way modifies the existing jurisdictional 
boundaries set forth in the Interagency Agreement, and any issues 
related to the rule that may arise between MSHA and OSHA are governed 
by this agreement. Therefore, the final rule does not necessitate a 
clarification of the jurisdictional limits.
    Federal Railroad Administration (FRA) jurisdictional concerns. The 
Association of American Railroads (AAR) and the American Short Line and 
Regional Railroad Association (ASLRRA) raised jurisdictional issues 
about railroad operations (Document ID 2366, pp. 3-4). The stated 
concern is that railroad operations are also regulated by FRA. AAR and 
ASLRRA questioned OSHA's jurisdiction over railroad activities that 
OSHA considered and costed in its preliminary economic analysis, 
notably those of ``ballast dumper'' and ``machine operator.'' AAR and 
ASLRRA disagreed with OSHA's inclusion of these job categories as being 
``non-operational,'' which allowed them to be included within the scope 
of the OSHA silica rule. AAR and ASLRRA asserted that the FRA has 
developed a special expertise, making the FRA uniquely qualified to 
play the primary role in the federal government's efforts to assure 
safe employment and places of employment for railroad employees engaged 
in activities related to railroad operations (Document ID 2366, pp. 3-
4).
    Section 4(b)(1) of the OSH Act limits OSHA's authority; the Act 
does not apply to working conditions of employees with respect to which 
other Federal agencies exercise statutory authority to prescribe or 
enforce standards or regulations affecting occupational safety or 
health. Many of the regulatory boundaries between FRA and OSHA are 
documented in an FRA policy statement that outlines the respective 
areas of jurisdiction between FRA and OSHA with regard to the railroad 
industry, but the FRA has also defined some boundaries through 
rulemaking (Document ID 0692 (43 FR 10583-10590 (3/14/78))). In 2003, 
FRA amended the Railroad Workplace Safety regulations, 49 CFR part 214, 
to require that new and employer-designated existing on-track roadway 
maintenance machines be equipped with, among other things, positive 
pressurized ventilation systems, and be capable of protecting employees 
in the cabs of the machines from exposure to air contaminants, 
including silica, in accordance with OSHA's air contaminants standard, 
29 CFR 1910.1000 (49 CFR 214.505). In that rulemaking, the FRA 
articulated the overlap of its authority with OSHA's concerning 
protection from air contaminants: ``when working inside the cab, 
workers receive protection from FRA; when working outside the cab, 
workers receive protection from OSHA'' (68 FR 44388, 44393-44394 (7/28/
03)). Consequently, this OSHA rule applies only to those railroad 
activities outside the cab (e.g., ballast dumping outside cabs) over 
which the FRA has not exercised jurisdiction, and only those activities 
are included in the final economic analysis. Additional discussion of 
this jurisdictional issue is included in the section on the 
technological feasibility of railroads (see Chapter IV of the Final 
Economic Analysis and Final Regulatory Flexibility Analysis (FEA)).
    Forms of silica covered. OSHA received comments about which forms, 
or polymorphs, of silica (e.g., quartz, cristobalite, tridymite) to 
include within the scope of the rule. The Industrial Minerals 
Association--North America and Ameren Corporation supported including 
all forms within the scope of the rule (Document ID 1760, p. 2; 2200, 
p. 2; 2315, p. 2). Other commenters made recommendations regarding 
specific forms of silica. For example, the National Industrial Sand 
Association (NISA) suggested including tridymite; however, the National 
Institute for Occupational Safety and Health (NIOSH) and the North 
American Insulation Manufacturers Association (NAIMA) did not support 
inclusion of tridymite due largely to its rarity in the workplace 
(Document ID 2195, p. 30; 2177, Attachment 2, p. 10; 4213, p. 4). 
Similarly, Southern Company recommended that neither tridymite nor 
cristobalite be included within the scope of the rule, due to their 
rarity in the workplace (Document ID 2185, p. 2, 6). The American 
Composites Manufacturers Association and Southern Company suggested 
that OSHA focus exclusively on quartz (Document ID 1732, p. 6; 2185, p. 
6). NAIMA suggested OSHA focus on both quartz and cristobalite 
(Document 4213, p. 4).
    As discussed in Section V of this preamble, Health Effects, OSHA 
has concluded, based on the available scientific evidence, that quartz,

[[Page 16705]]

cristobalite, and tridymite have similar toxicity and carcinogenic 
potency. Including all three forms of crystalline silica in the scope 
of the rule is therefore protective of the health of employees. 
Coverage of quartz, cristobalite, and tridymite in the scope of the 
rule maintains the coverage from OSHA's previous PELs for respirable 
crystalline silica; to eliminate one or more forms from the scope of 
the rule would lessen protections, contrary to what the OSH Act 
contemplates (see 29 U.S.C. 655(b)(8)). Therefore, the respirable 
crystalline silica rule applies to occupational exposure to respirable 
crystalline silica, as defined in paragraph (b) of each standard to 
include quartz, cristobalite, and tridymite.
    Some commenters contended that OSHA should differentiate between 
crystalline silica and amorphous silica in the scope of the rule. The 
Society for Protective Coatings stated that this differentiation would 
avoid confusion and unnecessary burden, especially for small businesses 
(Document ID 2120, p. 1; 3544, p. 16). NAIMA stated that NIOSH, IARC 
(the International Agency for Research on Cancer), EPA (the 
Environmental Protection Agency), and the California Office of 
Environmental Health Hazard Assessment all recognize the distinction in 
potential hazards to workers between amorphous and crystalline silica 
(Document ID 3544, p. 16). However, OSHA never intended to, and did 
not, include amorphous silica in the proposed rule. Nor do the final 
standards apply to amorphous silica. In fact, each standard bears the 
title, ``Respirable crystalline silica''; only the respirable fraction 
of crystalline silica, where it exists as quartz, cristobalite, and/or 
tridymite, is covered.
    Requests for exemptions. Commenters requested exemptions from the 
rule for specific operations or industries, such as auto body 
operations, cement distribution terminals, floor covering dealers, 
rural electric distribution cooperatives, and painting operations, 
arguing that these operations involve low levels of exposure to 
respirable crystalline silica (e.g., Document ID 2300, p. 4; 2358, p. 
15; 2359, pp. 3-7; 2365, p. 2; 3751, p. 2; 2239, pp. 4-5). For example, 
the National Automobile Dealers Association (NADA) said that the 
likelihood of worker exposure to significant respirable crystalline 
silica in dealership auto body operations is de minimis, largely due to 
product substitution, state-of-the-art work practices, and the use of 
respiratory protection. NADA requested that OSHA confirm this 
conclusion through a clear statement in the preamble of its final rule 
(Document ID 2358, p. 3). Similarly, the World Floor Covering 
Association requested that OSHA revise the rule to exempt retail 
flooring dealers and installers from all requirements in the standard 
based on the intermittent and de minimis exposure of its employees to 
crystalline silica (Document ID 2359, p. 11). The Portland Cement 
Association also requested an exemption from the silica rule, arguing 
that its contemporary inhalation survey and historical data show that 
there is no probability that respirable crystalline silica exposures 
can be generated above the proposed action level among employees at 
cement terminals.
    OSHA addresses the concerns of commenters regarding situations 
where they believe exposures are minimal and represent very little 
threat to the health of workers by including in the standards' scope 
and application sections an exception based on the level of exposure to 
respirable crystalline silica. Therefore, paragraph (a)(2) of the 
standard for general industry and maritime provides an exception for 
circumstances where the employer has objective data demonstrating that 
employee exposure to respirable crystalline silica will remain below 25 
micrograms per cubic meter of air (25 [mu]g/m\3\) as an 8-hour time-
weighted average (TWA) under any foreseeable conditions.
    OSHA concludes this approach is sensible policy because providing 
an exception for situations where airborne exposures are less likely to 
present significant risk allows employers to focus resources on the 
exposures of greatest occupational health concern. The Agency has 
included a definition for ``objective data'' in the rule (discussed 
with regard to Definitions) to clarify what information and data can be 
used to satisfy the obligation to demonstrate that respirable 
crystalline silica exposures will be below 25 [mu]g/m\3\ as an 8-hour 
TWA under any foreseeable conditions.
    When using the phrase ``any foreseeable conditions'' OSHA is 
referring to situations that can reasonably be anticipated. The Agency 
considers failure of engineering controls to be a situation that is 
generally foreseeable. Although engineering controls are usually a 
reliable means for controlling employee exposures, equipment does 
occasionally fail. Moreover, OSHA intends the requirements for training 
on control measures, housekeeping, and other ancillary provisions of 
the rule to apply where engineering controls are used to limit 
exposures. Without effective training on use of engineering controls, 
for example, it is unreasonable to expect that such controls will be 
used properly and consistently. Thus, the exception does not apply 
where exposures below 25 [mu]g/m\3\ as an 8-hour TWA are expected or 
achieved, but only because engineering or other controls are being used 
to limit exposures; in that circumstance, but for the controls, 
exposures above 25 [mu]g/m\3\ as an 8-hour TWA would be foreseeable, 
and are foreseeable in the event of control failure or misuse.
    OSHA considers the exclusion from the application of the rule for 
exposures below the 25 [mu]g/m\3\ action level to be a reasonable point 
of demarcation. For workplaces or tasks for which exposures are 
consistently below that threshold, it should be possible for employers 
to develop or obtain objective data demonstrating that employee 
exposure will remain below that level under any foreseeable conditions. 
Other standards have included similar exceptions (e.g., acrylonitrile, 
29 CFR 1019.1045; ethylene oxide, 29 CFR 1910.1047; 1,3-butadiene, 29 
CFR 1910.1051; chromium (VI), 29 CFR 1910.1026). In order for an 
employer to take advantage of this exclusion, the employer must have 
objective data demonstrating that employee exposure to respirable 
crystalline silica will remain below 25 [mu]g/m\3\ as an 8-hour TWA) 
under any foreseeable conditions, and must provide this data to the 
Assistant Secretary upon request.
    NADA's submission provides an example of data that can be used to 
meet the requirements of the standard (Document ID 4197; 4198). NADA 
conducted air monitoring for employees performing a variety of tasks in 
automobile body shops. NADA selected body shops from a random sample of 
members, and worked to ensure that those selected were not the most 
technologically advanced or cleanest in order to ensure that the 
results of the study were representative of typical operations. The 
sampling was conducted in accordance with procedures described in 
OSHA's Technical Manual, and techniques for controlling dust generated 
during sanding operations were recorded and monitored. NADA retained a 
consultant to review testing methodology and final results and worked 
with Maine's OSHA Consultation Program to gather samples. In the body 
shops sampled, all but one of the samples taken for respirable 
crystalline silica indicated that exposures were below the limit of 
detection. For the one sample where the level of exposure was above the 
limit of detection, the result was below 25 [mu]g/m\3\ as an 8-hour 
TWA. A body shop

[[Page 16706]]

performing tasks in a manner consistent with that described in the NADA 
submission would be able to rely on these objective data to demonstrate 
that exposures do not exceed 25 [mu]g/m\3\ as an 8-hour TWA under any 
foreseeable conditions.
    The construction standard, paragraph (a), also provides an 
exception where employee exposure will remain below 25 [mu]g/m\3\ as an 
8-hour TWA under any foreseeable conditions, but it does not require 
the employer to have objective data to support the exception. The data 
presented in Chapter IV of the FEA indicate that construction tasks can 
and often do involve exposures that exceed 25 [mu]g/m\3\ as an 8-hour 
TWA. However, some construction tasks may involve only minimal exposure 
to respirable crystalline silica. Some commenters indicated that they 
believed these tasks were covered under the scope of the proposed 
construction standard. For example, the Construction Industry Safety 
Coalition (CISC) and the National Association of Home Builders 
indicated that they believed that mixing mortar, pouring concrete 
footers, slab foundation, and foundation walls, and the removal of 
concrete formwork would be covered by the standard (Document ID 2319, 
pp. 19-21; 2296, pp. 8-9). OSHA finds that these tasks, when performed 
in isolation from activities that do generate significant exposures to 
respirable crystalline silica (e.g., tasks listed on Table 1, abrasive 
blasting), do not create respirable crystalline silica exposures that 
exceed 25 [mu]g/m\3\ as an 8-hour TWA. OSHA's analysis of the 
rulemaking record also indicates that a substantial number of employees 
in the construction sector perform tasks involving occasional, brief 
exposures to respirable crystalline silica that are incidental to their 
primary work. These employees include carpenters, plumbers, and 
electricians who occasionally drill holes in concrete or masonry or 
perform other tasks that involve exposure to respirable crystalline 
silica. CISC estimated that 1.5 million employees in the construction 
industry perform such tasks (Document ID 2319, pp. 72-73). Where 
employees perform tasks that involve exposure to respirable crystalline 
silica for a very short period of time, OSHA finds that exposures for 
many tasks will be below 25 [mu]g/m\3\ as an 8-hour TWA. Short-term 
respirable crystalline silica exposures must be very high in order for 
those exposures to exceed 25 [mu]g/m\3\ as an 8-hour TWA; for example, 
if an employee is exposed for only 15 minutes, his or her exposure 
would have to exceed 800 [micro]g/m\3\ for that 15 minute period before 
the 8-hour TWA exposure would exceed 25 [mu]g/m\3\.
    When performed without adequate controls, some tasks can generate 
such high exposures. However, for some construction tasks that may be 
performed occasionally, for brief periods of time, exposures would not 
generally be expected to exceed 25 [mu]g/m\3\ as an 8-hour TWA. For 
example, for hole drillers using hand-held drills, the highest result 
identified in OSHA's exposure profile was for a worker performing dry 
drilling on a wall on the lower level of a concrete parking garage 
where air circulation was poor (see Chapter IV of the FEA). This result 
showed an exposure of 300 [micro]g/m\3\ during the sampling period 
(Document ID 1423, p. 833). If the duration of exposure was 15 minutes, 
the 8-hour TWA exposure would be 19 [mu]g/m\3\, and therefore under the 
25 [mu]g/m\3\ threshold (assuming no exposure for the remainder of the 
shift).
    Rather than require construction employers to develop objective 
data to support an exception from the construction standard for 
employees who are exposed to minimal levels of respirable crystalline 
silica, or who are occasionally exposed to respirable crystalline 
silica for brief periods, OSHA is structuring the scope paragraph 
(i.e., paragraph (a)) for the construction standard so that the 
standard applies to all occupational exposures to respirable 
crystalline silica, except where employee exposure will remain below 25 
[mu]g/m\3\ as an 8-hour TWA under any foreseeable conditions. This 
approach relieves construction employers of the burden of developing 
objective data for such situations.
    In the NPRM, OSHA asked stakeholders whether the Agency should 
limit the coverage of the rule to materials that contain a threshold 
concentration (e.g., 1 percent, 0.1 percent) of crystalline silica (78 
FR at 56288). Stakeholders representing industries including cement and 
concrete, composites manufacturing, fertilizers, and sand and gravel 
suggested a threshold, commonly presenting concerns regarding 
requirements for labels and safety data sheets (SDSs) (e.g., Document 
ID 1785, p. 4; 2116, Attachment 1, p. 45; 2179, pp. 3-4; 2101, pp. 8-9; 
2284, p. 10; 2296, p. 44; 2312, p. 3; 2317, p. 3; 2319, p. 120; 2327, 
Attachment 1, p. 14; 4208, pp. 19-20). For example, TFI supported a 
percentage-based threshold for crystalline silica containing materials, 
indicating that such an approach would be consistent with OSHA's past 
standard-setting experience for asbestos-containing materials. TFI 
stated that OSHA should not set a threshold at lower than 1 percent, 
and recommended that OSHA consider a 5 percent threshold, noting 
challenges in measuring crystalline silica content in bulk materials at 
concentrations below 1 percent (Document ID 2101, pp. 5-9).
    OSHA has not included a threshold concentration exception in these 
standards. The Agency has concluded that it would not be appropriate to 
establish a threshold crystalline silica concentration because the 
evidence in the rulemaking record is not sufficient to lead OSHA to 
determine that the suggested concentration thresholds would be 
protective of employee health. The Agency's exposure assessment 
findings show that exposures to respirable crystalline silica can 
exceed the action level of 25 mg/m\3\ or PEL of 50 mg/m\3\ even at 
threshold concentrations less than 1 or 0.1 percent, as demonstrated by 
the abrasive blasting activities investigated in a NIOSH survey report 
using Staurite XL in containment (Document ID 0212, p. 12). Issues with 
regard to requirements for labels and SDSs are addressed in the summary 
and explanation of requirements for Communication of Respirable 
Crystalline Silica Hazards to Employees in this preamble.
    The Brick Industry Association (BIA) argued that its members should 
be exempt from compliance with the respirable crystalline silica rule, 
indicating that the low toxicity of crystalline silica in the brick and 
structural clay industry does not cause a material risk of health 
impairment. BIA noted that OSHA has established specific requirements 
for certain industries in the past, such as the pulp, paper and 
paperboard mill industry in 29 CFR 1910.216, and the textile industry 
in 29 CFR 1910.262. BIA requested that OSHA take a similar approach for 
the brick industry because, BIA argued, silicosis is essentially non-
existent in the brick industry's workers (Document ID 2300, pp. 2-4). 
OSHA also received comments and testimony from stakeholders in the 
brick, tile, and fly ash industries who argued that in their 
industries, crystalline silica was most commonly shrouded or occluded 
within matrices of aluminosilicates, and therefore the silica was less 
bioavailable and exhibited reduced toxicity (e.g., Document ID 2085, p. 
2; 2123, p. 1; 2267, p. 8; 2343, Attachment 1, p. 30; 3587, Tr. 3628; 
3587, Tr. 3704).
    As discussed in Section V of this preamble, Health Effects, OSHA 
has reviewed the evidence concerning potential effects on silica-
related toxicity of a variety of physical factors,

[[Page 16707]]

including the age of fractured surfaces of the crystal particle and 
clay occlusion of the particle. OSHA recognizes that the risk to 
employees exposed to a given level of respirable crystalline silica may 
not be equivalent in different work environments due to differences in 
physical factors that affect the potency of crystalline silica. OSHA 
also recognizes that workers in these industries (e.g., brick 
manufacturing) may experience lower rates of silicosis and other health 
effects associated with exposure to respirable crystalline silica. 
However, OSHA finds that these employees are still at significant risk 
of developing adverse health effects from exposure to respirable 
crystalline silica. The Agency is therefore is not excluding brick, 
tile, or fly ash from the scope of the rule based on physical 
characteristics of crystalline silica.
    OSHA also received multiple studies, along with testimony and 
comments from the Sorptive Minerals Institute (SMI) (Document ID 2377; 
4230). SMI stated that sorptive clays are limited to a specific and 
discreet subset of deposits in the U.S., including specifically: The 
Monterey formation (California), the Porters Creek formation 
(Mississippi Valley), the Twiggs and Meigs fullers earth (southeastern 
U.S.), the Wyoming or Western-type sodium bentonite deposits, the 
calcium bentonite deposits (north-central Florida), and the fullers 
earth deposits of eastern Virginia (Document ID 4230, p. 3). As 
discussed in Section V, Health Effects, SMI contended that silica in 
sorptive clays exists as either amorphous silica or as geologically 
ancient, occluded quartz, and that neither form poses the health risk 
described in OSHA's risk assessment (Document ID 4230, p. 2). After 
evaluation of the evidence SMI submitted to the record, OSHA finds that 
quartz originating from bentonite and similar sorptive clays is 
considerably less toxic than unoccluded quartz, and evidence does not 
exist that would permit the Agency to evaluate the magnitude of the 
lifetime risk resulting from exposure to silica in sorptive clay 
deposits. OSHA is therefore excluding sorptive clays from the scope of 
the rule, as described in paragraph (a)(1) of the general industry and 
maritime standard. The PEL in 29 CFR 1910.1000 Table Z-3 (i.e., the 
formula that is approximately equivalent to 100 [mu]g/m\3\) will 
continue to apply to occupational exposure to respirable crystalline 
silica from sorptive clays. The exemption covers exposures resulting 
from the processing, packaging, and distribution of sorptive clays 
originating from the geological deposits described above (and intended 
for sorptive clay-specific use such as absorbents for oil, grease, and 
animal waste, as a carrier for pesticides and fertilizers, or in 
cosmetics, pharmaceuticals, and animal feeds).
    Relationship to other OSHA standards. EEI and the American Iron and 
Steel Institute (AISI) sought clarification from OSHA regarding how the 
silica rule would affect the existing coke oven emissions standard or 
the PEL for coal dust. EEI said that OSHA should expressly exempt coal 
dust from the rule (Document ID 2357, p. 4). AISI similarly stated that 
the rule potentially conflicts with the coal dust PEL and is 
duplicative of existing steel industry standards. AISI stated that 
OSHA's existing coke oven emissions standard protects employees working 
in the regulated area around metallurgical coke ovens and metallurgical 
coke oven batteries where exposures to emissions are of greatest 
concern. AISI believes that workers covered by OSHA's coke oven 
emissions standard are therefore already protected adequately from the 
dangers of crystalline silica exposure and such operations should be 
exempt from the rule (Document ID 3492, p. 2).
    The respirable crystalline silica rule has no effect upon OSHA's 
standard for coke oven emissions, the existing PEL for coal dust, or 
any other substance-specific standard. None of these requirements 
provide the full range of protections afforded by the respirable 
crystalline silica rule. The PEL for coal dust is only a PEL; it does 
not provide any additional protections, such as medical surveillance. 
Other requirements therefore do not provide protection equivalent to 
the respirable crystalline silica rule. Accordingly, the silica rule 
applies to these situations to the extent there is silica exposure and 
the conditions for excluding them from the rule's scope are not met.

Definitions

    Paragraph (b) of the standard for general industry and maritime 
(paragraph (b) of the standard for construction) provides definitions 
of terms used in the standards.
    ``Action level'' means a concentration of airborne respirable 
crystalline silica of 25 micrograms of respirable crystalline silica 
per meter cubed of air ([mu]g/m\3\), calculated as an 8-hour time-
weighted average. The action level triggers requirements for exposure 
assessment and, in the standard for general industry and maritime, 
medical surveillance. The definition is unchanged from the proposal.
    Because of the variable nature of employee exposures to airborne 
concentrations of respirable crystalline silica, maintaining exposures 
below the action level provides reasonable assurance that employees 
will not be exposed to respirable crystalline silica at levels above 
the permissible exposure limit (PEL) on days when no exposure 
measurements are made. Even when all measurements on a given day fall 
below the PEL but are above the action level, there is a reasonable 
chance that on another day, when exposures are not measured, the 
employee's actual exposure may exceed the PEL (Document ID 1501). The 
importance of the action level is explained in greater detail in the 
summary and explanation of Exposure Assessment and summary and 
explanation of Medical Surveillance.
    The action level in this rule is set at one-half of the PEL. This 
is the same ratio of action level to PEL that has been used and been 
effective in other standards, including those for inorganic arsenic (29 
CFR 1910.1018), ethylene oxide (29 CFR 1910.1047), benzene (29 CFR 
1910.1028), methylene chloride (29 CFR 1910.1052), and chromium (VI) 
(29 CFR 1910.1026).
    Following the publication of the proposed rule, OSHA received a 
number of comments pertaining to the definition of the action level. 
Some commenters, such as National Council for Occupational Safety and 
Health (NCOSH), American Federation of Labor and Congress of Industrial 
Organizations (AFL-CIO), International Brotherhood of Teamsters, United 
Steelworkers (USW), Center for Effective Government (CEG), American 
Public Health Association (APHA), American Thoracic Society (ATS), and 
Cara Evens, a private citizen, supported OSHA's proposal to include an 
action level of 25 [mu]g/m\3\ (e.g., Document ID 1801, p. 2; 2173, pp. 
2-3; 2175, p. 5; 2178, Attachment 1, p. 2; 2318, p. 10; 2336, p. 5; 
2341, pp. 2-3; 4204, pp. 42-45, 51-52). For example, USW supported the 
inclusion of an action level that is half the PEL (25 [micro]g/m\3\) 
because:

    This action level will further reduce exposure to respirable 
crystalline silica by workers and will incentivize employers to 
implement best-practice controls keeping exposures at a minimum as 
well as reducing costs of monitoring and assessments. The USW 
believes measuring airborne concentrations of silica at 25ug/m\3\ 
will prove feasible given current sampling techniques (Document ID 
2336, p. 5).

    AFL-CIO noted that action levels have long been incorporated into 
OSHA standards in recognition of the variability of workplace exposures 
and argued that the inclusion of an action level is particularly 
important in this

[[Page 16708]]

rulemaking because exposures at the PEL pose a significant risk to 
employees (Document ID 2256, Attachment 2, p. 9). NCOSH and CEG echoed 
AFL-CIO's concerns about significant risk remaining at the PEL, and 
NCOSH, further noted that significant risk remains at the action level 
(Document ID 2173, p. 2; 2341, p. 2).
    As discussed in more detail in the summary and explanation of 
Medical Surveillance, some stakeholders, such as APHA, supported an 
action level trigger for medical surveillance in the standard for 
general industry because of significant risk of disease remaining at 
the action level and even below (Document ID 2178, Attachment 1, p. 2).
    The National Institute for Occupational Safety and Health (NIOSH) 
supported an action level that is lower than the PEL because it is 
consistent with longstanding industrial hygiene practice, and an action 
level is included in other OSHA standards. NIOSH did not recommend a 
value for the action level but cited a 1975 study by NIOSH (Leidel et 
al. 1975, Document ID 1501) as demonstrating that an action level 
provides a high level of confidence that most daily exposures will be 
below the PEL (Document ID 2177, Attachment B, p. 23).
    Other commenters supported having an action level, but advocated a 
higher level (e.g., Document ID 1963, pp. 1-2; 2196, Attachment 1, pp. 
1-2; 2200, pp. 1-2; 2213, p. 3; 2232, p. 1; 2233, p. 1; 2301, 
Attachment 1, p. 78; 2311, p. 3). For instance, the National Industrial 
Sand Association (NISA) recommended an action level of 50 [mu]g/m\3\, 
which is one half the value of the PEL they supported (100 [mu]g/m\3\). 
NISA recommended a higher PEL because it disagreed with OSHA that 
significant risk existed at the proposed PEL of 50 [mu]g/m\3\. NISA 
also argued that a PEL of 50 [mu]g/m\3\ would not be technologically or 
economically feasible. However, NISA's reasons for recommending an 
action level set at half of its recommended PEL mirrored many of the 
reasons offered by USW and AFL-CIO, including maintaining consistency 
with other OSHA standards, accounting for exposure variability, and 
providing employers with incentives to keep exposures low. In addition, 
NISA commented that keeping exposures well below the PEL would provide 
a margin of safety to protect against uncertainties in the toxicology 
and epidemiology data supporting a PEL (Document ID 2195, pp. 30-35). 
NISA also recommended that medical surveillance be triggered at the 
action level (although, as noted above, NISA recommended an action 
level of 50 [mu]g/m\3\); that recommendation is discussed in the 
summary and explanation of Medical Surveillance.
    Southern Company asserted that OSHA set the proposed action level 
too low, because it believed it is difficult to measure based on 
current laboratory detection limits (Document ID 2185, pp. 5-6). It 
recommended that OSHA consider setting the action level at an 
achievable analysis level (though a suggested level for OSHA to 
consider was not provided) or conduct further cost analyses of 
additional sampling and ancillary provisions this may trigger. As 
stated further below, OSHA's conclusion that silica exposures can be 
measured with reasonable accuracy at the action level is discussed in 
the Sampling and Analysis discussion of technological feasibility in 
Chapter IV of the Final Economic Analysis and Final Regulatory 
Flexibility Analysis (FEA).
    Other commenters supported an action level but argued that the 
proposed action level was set too high. For example, the United 
Automobile, Aerospace and Agricultural Implement Workers of America 
(UAW) argued that the action level would need to be set at 12.5 [mu]g/
m\3\, one-fourth of a 50 [mu]g/m\3\ PEL, in order to ensure that fewer 
than 5 percent of exposures would exceed a PEL of 50 [mu]g/m\3\ 
(Document ID 2282, Attachment 3, p. 14). In support of its recommended 
action level, UAW cited a study by Rappaport et al. (1988), which 
reported that no more than 12 percent of log-normally distributed 
exposures are expected to exceed the PEL with an action level set at 
one half the PEL (Document ID 2282, Attachment 2, pp. 310, 314). 
Similarly, the BlueGreen Alliance (BGA) supported a lower action level, 
indicating that the proposed action level was not protective enough. 
BGA supported an action level of no higher than 25 percent of the PEL 
``. . . in order to provide reasonable likelihood that 95% of exposures 
are below the PEL'' (Document ID 2176, p. 2).
    Finally, some commenters opposed having any action level (Document 
ID 2085, p. 3; 2296, p. 40; 2305, pp. 4, 10; 2312, p. 2; 2317, p. 2; 
2327, Attachment 1, pp. 13, 15-17; 2305, pp. 4, 10; 2296, p. 40; 3577, 
Tr. 707-708). Mercatus Center of George Mason University (Mercatus 
Center) asserted that OSHA did not provide adequate justification for 
the proposed action level, arguing that because OSHA found a PEL of 25 
[mu]g/m\3\ to be infeasible, the Agency has not shown that employers 
would have sufficient incentives to limit exposures to the action level 
(Document ID 1819, p. 2). The Fertilizer Institute indicated that the 
action level will create a de facto 25 [mu]g/m\3\ standard because the 
initial and periodic monitoring requirements will be a time-consuming, 
expensive endeavor (Document ID 2101, pp. 7-8). The National Concrete 
Masonry Association and Blue Stone Block Supermarket argued that the 
best approach would be to remove the action level and only ``require 
action when the PEL is exceeded'' (Document ID 2279, p. 9; 2384, p. 9). 
They believed requiring action only when their recommended PEL of 100 
[micro]g/m\3\ is exceeded would be effective in reducing silica-related 
illnesses and more cost-effective for industries.
    OSHA considered these comments and has decided to retain an action 
level of 25 [micro]g/m\3\. OSHA agrees with CEG and AFL-CIO that that 
the inclusion of an action level of 25 [micro]g/m\3\ is particularly 
important in this rulemaking because employees exposed at the action 
level and revised PEL remain at significant risk of developing 
respirable crystalline silica-related diseases (see Section VI, Final 
Quantitative Risk Assessment and Significance of Risk). In addition, as 
explained in Chapter IV of the FEA, OSHA has found that the revised PEL 
is technologically and economically feasible. OSHA disagrees with 
Mercatus Center that an action level of 25 [micro]g/m\3\ is not 
appropriate because that level is not feasible as a PEL, and the Agency 
does not agree with the Fertilizer Institute that a 25 [mu]g/m\3\ 
action level creates a de facto standard. The action level only 
triggers certain requirements (i.e., a requirement for exposure 
assessment in general industry/maritime and construction, and medical 
surveillance in general industry/maritime only); employers that exceed 
it but remain at the PEL or below will not be in violation of the rule, 
so long as they comply with the requirements associated with the action 
level. The requirements associated with exposures at or above the 
action level create an incentive--but not a requirement--for employers 
to reduce exposures below the action level where it is reasonably 
possible to do so. Although OSHA could not find that engineering 
controls and work practices are sufficient to reduce and maintain 
respirable crystalline silica exposures to a level of 25 [mu]g/m\3\ or 
below in most operations most of the time in affected industries, it is 
likely possible for some employers to reduce exposures to below the 
action level in some circumstances, without the use of respirators. The 
Agency also concludes that it is feasible to measure respirable 
crystalline silica levels at an action level of 25 [mu]g/m\3\ with 
reasonable accuracy (see Chapter IV of the FEA). Because employers are 
not required to reduce

[[Page 16709]]

exposures below 25 [mu]g/m\3\, feasibility concerns are not relevant. 
Consequently, OSHA does not agree with NISA and Southern Company that 
feasibility concerns warrant revising the proposed action level upward.
    OSHA agrees, however, that maintaining exposures below an action 
level that is half the PEL provides reasonable assurance that employees 
will not be exposed to respirable crystalline silica at levels above 
the PEL on days when no exposure measurements are made. OSHA's early 
standards relied, in part, on a statistical basis for using an action 
level of one-half the PEL (e.g., acrylonitrile, 29 CFR 1910.1045; 
ethylene oxide, 29 CFR 1910.1047). OSHA previously determined (based in 
part on research conducted by Leidel et al., 1975) that where exposure 
measurements are above one-half the PEL, the employer cannot be 
reasonably confident that the employee is not exposed above the PEL on 
days when no measurements are taken (Document ID 1501, pp. 5-6, 29-30, 
38). Similarly, Rappaport et al. (1988) used monitoring data and 
applied a statistical method to estimate that no more than 12 percent 
of lognormally-distributed exposures would be expected to exceed the 
PEL if mean exposures remain below an action level set at one-half the 
PEL (Document ID 2282, Attachment 2).
    OSHA thus agrees with UAW and BGA that an action level lower than 
one-half of the PEL would provide a higher degree of confidence that 
exposures are not likely to exceed the PEL. However, OSHA's policy is 
to set the action level at a value that effectively encourages 
employers to reduce exposures below the action level while still 
providing reasonable assurance that employee exposures are typically 
below the PEL. The Agency's experience with previous standards also 
indicates that an action level of one-half the PEL effectively 
encourages employers, where feasible, to reduce exposures below the 
action level to avoid the added costs of required compliance with 
provisions triggered by the action level.
    OSHA is convinced, therefore, that an action level is needed and 
decided to set the action level at one-half of the PEL, based on 
residual risk at the PEL of 50 [mu]g/m\3\, the feasibility of measuring 
exposures at an action level of 25 [mu]g/m\3\, and the administrative 
convenience of having the action level set at one-half the PEL, as it 
is in other OSHA standards. OSHA's risk assessment indicates that 
significant risk remains at the PEL of 50 [mu]g/m\3\. OSHA therefore 
has a duty to impose additional requirements on employers to reduce 
remaining significant risk when those requirements will afford benefits 
to employees and are feasible (Building and Construction Trades 
Department, AFL-CIO v. Brock, 838 F.2d 1258, 1269 (D.C. Cir 1988)). 
With significant risk remaining at 50 [mu]g/m\3\, reducing that risk by 
incorporating an action level is necessary and appropriate. OSHA 
concludes that the action level will result in a real and necessary 
further reduction in risk beyond that provided by the PEL alone.
    ``Competent person'' means an individual who is capable of 
identifying existing and foreseeable respirable crystalline silica 
hazards in the workplace and who has authorization to take prompt 
corrective measures to eliminate or minimize them. The competent person 
must also have the knowledge and ability necessary to fulfill the 
responsibilities set forth in paragraph (g) of the construction 
standard. OSHA has not included requirements related to a competent 
person in the general industry and maritime standard. This definition 
therefore is included only in the construction standard.
    In the proposal, OSHA defined competent person as one who is 
capable of identifying existing and predictable respirable crystalline 
silica hazards in the surroundings or working conditions and who has 
authorization to take prompt corrective measures to eliminate them. 
OSHA received a number of comments related to this definition. Many of 
these commenters suggested that the definition should be expanded. For 
example, Building and Construction Trades Department, AFL-CIO (BCTD) 
recommended that OSHA revise the proposed definition to require that 
the competent person be capable of identifying the proper methods to 
control existing and predictable hazards in the surroundings or working 
conditions. BCTD also asked that the definition specify that the 
competent person be ``designated by the employer to act on the 
employer's behalf.'' It proposed specific language that incorporated 
these suggestions (Document ID 4223, p. 112). International Union of 
Operating Engineers (IUOE) endorsed the BCTD definition and 
International Union of Bricklayers and Allied Craftworkers (BAC) agreed 
with BCTD that OSHA's definition needed to be more fully developed 
(Document ID 2262, p. 40; 2329, p. 5).
    The American Society of Safety Engineers (ASSE) advocated for the 
following definition, which it based on that of the asbestos standard:

    Competent person means, in addition to the definition in 29 CFR 
1926.32(f), one who is capable of identifying existing respirable 
crystalline silica hazards in the workplace and selecting the 
appropriate control strategy for such exposure and for developing 
and overseeing written access control plans, who has the authority 
to take prompt corrective measures to eliminate such hazards, as 
specified in 29 CFR 1926.32(f), and who is trained in a manner 
consistent with OSHA requirements for training (Document ID 4201, 
pp. 3-4).

    Finally, NIOSH noted the American National Standards Institute 
(ANSI) AIO.38 definition of competent person:

    One who, as a result of specific education, training, and/or 
experience, is capable of identifying existing and predictable 
hazards in the surroundings [or] working conditions that are 
unsanitary, hazardous or dangerous to employees, and who has the 
authorization and responsibility to take prompt corrective measures 
to eliminate them [emphasis omitted] (as cited in Document ID 2177, 
Attachment B, p. 9).

    In determining if the proposed definition for competent person 
needed to be revised, OSHA considered these comments and the definition 
of competent person in the safety and health regulations for 
construction (29 CFR 1926.32(f)). Under 29 CFR 1926.32(f), competent 
person is defined as one capable of identifying existing and 
predictable hazards in the surroundings or working conditions that are 
unsanitary, hazardous, or dangerous to employees and who is authorized 
to take prompt corrective measures to eliminate them. OSHA concludes 
that its definition for competent person is consistent with 1926.32(f) 
but tailored to respirable crystalline silica by specifying 
``respirable crystalline silica hazards'' instead of ``unsanitary, 
hazardous, or dangerous'' conditions. OSHA did make a few minor 
revisions to its proposed definition. The Agency replaced the word 
``one'' with ``individual,'' which is merely an editorial change. The 
Agency removed the phrase ``in the surroundings or working conditions'' 
and changed it to ``in the workplace'' to make it specific to the 
workplace. The Agency removed the phrase ``to eliminate them'' and 
changed it to ``to eliminate or minimize them'' to denote there may be 
cases where complete elimination would not be feasible. OSHA also 
changed ``predicted'' to ``foreseeable'' to make the wording consistent 
with the scope of the standard (paragraph (a)).
    OSHA agrees with ASSE and the ANSI definition highlighted by NIOSH 
that the definition for competent person must indicate that the 
competent person has appropriate training, education, or experience. 
Therefore, OSHA further

[[Page 16710]]

revised the proposed definition for competent person to indicate that 
the competent person must have the knowledge and ability necessary to 
fulfill the responsibilities set forth in paragraph (g). Comments 
regarding knowledge or training for a competent person and OSHA's 
responses to those comments are discussed in the summary and 
explanation of Written Exposure Control Plan.
    The requirement that the competent person have the knowledge and 
ability to fulfill the responsibilities set forth in paragraph (g) 
addresses BCTD's and ASSE's requests to amend the definition to specify 
that the competent person be capable of identifying or selecting the 
proper methods to control hazards in the surroundings or working 
conditions. It is clear from paragraph (g) that the competent person 
must be familiar with and also capable of implementing the controls and 
other protections specified in the written exposure control plan.
    ASSE also requested that the definition indicate that the competent 
person be capable of developing and overseeing the written access 
control plan, which OSHA had proposed. However, the final rule does not 
specify a written access control plan, and instead requires a written 
exposure control plan. Regardless, OSHA does not agree with ASSE's 
suggestion that the definition should be revised to indicate capability 
to develop a written plan. OSHA assigns that responsibility to the 
employer because under paragraph (g)(4), the competent person is 
someone on the job site who makes frequent and regular inspections, and 
thus may not be involved in developing the written exposure control 
plan in an office environment. OSHA also disagrees with BCTD that the 
definition should specify that the competent person is designated by 
the employer to act on behalf of the employer. The employer's 
obligation to designate a competent person is clearly specified in 
paragraph (g)(4) and the definition clearly states that the competent 
person has authority to promptly apply corrective measures.
    The competent person concept has been broadly used in OSHA 
construction standards (e.g., 29 CFR 1926.32(f) and 1926.20(b)(2)), 
particularly in safety standards. This standard does not affect the 
competent person provisions in these other standards.
    ``Employee exposure'' means the exposure to airborne respirable 
crystalline silica that would occur if the employee were not using a 
respirator. This definition clarifies the requirement that employee 
exposure must be measured as if no respiratory protection is being 
worn. The definition, which is consistent with OSHA's previous use of 
the term in other standards, did not generate any comment and is 
unchanged from the proposal.
    ``High-efficiency particulate air (HEPA) filter'' means a filter 
that is at least 99.97 percent efficient in removing mono-dispersed 
particles of 0.3 micrometers in diameter. The definition is unchanged 
from the proposal. HEPA filters are more efficient than membrane 
filters because they are designed to target much smaller particles. In 
the housekeeping requirements of paragraph (h)(1) of the standard for 
general industry and maritime (paragraph (f)(1) of the standard for 
construction), OSHA refers to HEPA-filtered vacuuming as an example of 
an appropriate cleaning method, and the Table 1 entry for handheld and 
stand-mounted drills requires use of a HEPA-filtered vacuum (if a 
commercially available hole-cleaning kit connected to a dust collector 
is not being used). OSHA had also proposed HEPA-filtered dust 
collectors as controls for some tasks listed on Table 1 of the proposed 
standard for construction.
    The Agency received one comment related to HEPA filters from the 
Occupational and Environmental Health Consulting Services (OEHCS). 
First, OEHCS recommended that the definition be expanded to indicate 
that HEPA filters are effective at removing particles in the 0.3-
micrometer size range, as measured by a laser particle counter. Second, 
it requested addition of the term ``Portable High Efficiency Air 
Filtration (PHEAF)'' device, defined as a portable device equipped with 
a certified HEPA filter that, when tested as a complete unit, is 99.97 
percent effective in removing particles in the 0.3-micrometer size 
range, as measured by a laser particle counter (Document ID 1953, pp. 
4-6). OEHCS advocated for a requirement that portable filtration 
devices (e.g., HEPA vacuums, dust collectors used on tools, and filter 
systems for enclosed cabs) meet the definition of PHEAF. It argued that 
HEPA vacuums or other portable filtration devices might not perform 
effectively in the field due to inadequate, damaged, or deteriorating 
sealing surfaces; replacement filters that do not fit correctly; filter 
cabinets that are damaged; or filters that are punctured. Claiming that 
damaged filters might not build up enough pressure differential to 
signal that they should be changed, OEHCS recommended a requirement for 
field testing the devices using a laser particle counter to ensure that 
HEPA filters function as intended (Document ID 1953, Attachment 1, pp. 
2-4).
    OSHA encourages employers to ensure that HEPA filters function in 
the field according to the specifications of this definition. However, 
the Agency concludes that it is not appropriate to include requirements 
for PHEAF devices, as defined by OEHCS, or laser particle counting 
testing, in the rule due to the lack of documented effectiveness or 
consistency with the definition and because of the lack of support in 
the record. As a result, OSHA is retaining its proposed definition for 
HEPA filter and is not adding PHEAF to the definitions section.
    ``Objective data'' means information, such as air monitoring data 
from industry-wide surveys or calculations based on the composition of 
a substance, demonstrating employee exposure to respirable crystalline 
silica associated with a particular product or material or a specific 
process, task, or activity. The data must reflect workplace conditions 
closely resembling or with a higher exposure potential than the 
processes, types of material, control methods, work practices, and 
environmental conditions in the employer's current operations.
    The proposed definition of ``objective data'' also included 
``calculations based on the . . . chemical and physical properties of a 
substance'' as an example of a type of objective data that might 
demonstrate employee exposure to respirable crystalline silica. BCTD 
objected to this example's inclusion in the definition (Document ID 
2371, Attachment 1, pp. 11-12). Although BCTD agreed that the chemical 
and physical properties of a substance are among the factors that may 
be relevant in determining whether data from one set of circumstances 
can be used to characterize the exposures in other circumstances, BCTD 
stated that the proposed definition suggested that the chemical and 
physical properties of the material could be determinative in every 
instance. It also maintained that on construction sites the work 
processes themselves are more consistently a significant predictor of 
ambient silica exposures than percentage of silica in the material 
itself. Finally, BCTD argued that it is very important to focus not 
only on the overall operation, but also the specific silica dust-
generating task.
    In including this item in the definition, OSHA did not intend to 
imply that it would be relevant in all circumstances. Nonetheless, OSHA 
has removed the phrase ``chemical and physical properties'' from the 
final definition of ``objective data'' because it has concluded that a 
substance's

[[Page 16711]]

chemical and physical properties are not typically relevant for 
demonstrating exposures to respirable crystalline silica. However, in 
those instances where a substance's physical and chemical properties 
demonstrate employee exposure to respirable crystalline silica 
associated with a particular product or material or a specific process, 
task, or activity, an employer may use that information as objective 
data under this rule.
    The proposed rule also stated that objective data is information 
demonstrating employee exposure to respirable crystalline silica 
associated with a particular product or material or a specific process, 
operation, or activity. Throughout this rule, OSHA has often replaced 
the word ``operation'' with the word ``task'' (see summary and 
explanation of Specified Exposure Control Methods for further 
discussion). OSHA has made the change to ``task'' (instead of 
``operation'') in this definition to remain consistent with that 
change. This is also consistent with NIOSH's recommendation to add 
specificity to the definition by including the term ``task'' (Document 
ID 2177, Attachment B, p. 12).
    In addition, the proposal indicated that ``objective data'' needed 
to reflect workplace conditions closely resembling the processes, types 
of material, control methods, work practices, and environmental 
conditions in the employer's current operations. Dow Chemical Company 
stated that this requirement is generally appropriate, but argued that 
when data pertain to a more challenging work environment with higher 
potential for exposure, those data should be considered objective data 
(Document ID 2270, p. 2). It explained:

    If data from a more challenging environment demonstrate 
compliance with the Permissible Exposure Limit, then one may infer 
with confidence that workers in a less challenging environment 
(i.e., with less potential for exposure) are also not exposed above 
the PEL. Even if the two work environments are not ``closely 
resembling,'' the data are still an objective, valid method of 
screening workplaces that have a clearly lower risk of exposure 
(Document ID 2270, p. 2).

    OSHA agrees with Dow that data pertaining to an environment with 
higher exposure potential can be used as objective data for other 
environments with less potential for exposure. Therefore, OSHA added 
``or with a higher exposure potential'' to the definition.
    Edison Electric Institute (EEI) requested that OSHA harmonize the 
definition of ``objective data'' throughout its regulations (Document 
ID 2357, p. 22). OSHA recognizes that the term has evolved over time 
based on the Agency's experience implementing those standards. 
``Objective data'', as defined in this standard, is based on the record 
in this rulemaking and reflects an appropriate definition in the 
context of exposures to respirable crystalline silica. Additionally, 
OSHA has established a process, the Standards Improvement Project, to 
improve and streamline OSHA standards, including the revision of 
individual requirements within rules that are inconsistent. OSHA will 
consider reviewing the consistency of this definition in the next 
iteration of this ongoing effort.
    Many commenters suggested that OSHA add specificity with regards to 
what is considered objective data and establish criteria for objective 
data in the definition (e.g., Document ID 2177, Attachment B, p. 11; 
2181, p. 5; 2253, p. 4; 2256, Attachment 2, p. 10; 2339, p. 7; 2371, 
Attachment 1, p. 12; 2379, Appendix 1, pp. 54-55; 2380, Attachment 2, 
p. 26; 4223, p. 70). As discussed in the summary and explanation of 
Exposure Assessment, OSHA intends for the performance option to give 
employers flexibility to accurately characterize exposures using 
whatever processes or data are most appropriate for their 
circumstances. The Agency concludes it would be inconsistent to include 
specifications or criteria in the definition of objective data and thus 
has not done so here.
    Commenters also provided examples of alternative exposure 
measurement and characterization strategies that could generate 
objective data, such as: area sampling (Document ID 2195, pp. 36-37); 
area exposure profile mapping (Document ID 2379, Appendix 1, pp. 48-
49); real-time monitoring (Document ID 2256, Attachment 3, p. 12; 2357, 
pp. 37-38; 2379, Appendix 1, pp. 48-49, 55-56; 3578, Tr. 941-942; 3579, 
Tr. 161-162; 3588, Tr. 3798-3800; 4204, p. 56); and geotechnical 
profiling with testing for crystalline silica content (Document ID 
2262, p. 13). Trolex LTD pointed to emerging methods and technologies, 
such as new optical methods for particle counting and identification, 
which might provide enhanced measurements of real-time employee 
exposure to respirable crystalline silica in the future (Document ID 
1969, p. 2).
    In addition, commenters provided specific examples of types of 
information and information sources that they felt should be considered 
objective data. For example, the American Foundry Society (AFS) 
commented that objective data should include data that permits reliable 
estimation of exposure, such as: data from real-time monitors and area 
exposure mapping; data from less than full-shift samples where 
professional judgment can be used to determine exposure levels; and 
exposure data where the percent of silica is calculated using a 
historical average for the area or operation involved (Document ID 
2379, Appendix 1, pp. 54-55). The National Association of Manufacturers 
suggested the following as reliable sources of objective data: 
published scientific reports in the open scientific literature; NIOSH 
Health Hazard Evaluations; insurance carriers' loss prevention reports; 
and information that the silica in a process cannot be released because 
it is bound in a matrix preventing formation of respirable particles 
(Document ID 2380, Attachment 2, p. 26). ASSE identified industry-wide 
data, safety data sheets from product manufacturers, prior historical 
sampling data under comparable conditions, and aggregated company-wide 
sampling information as reliable sources of objective data (Document ID 
3578, Tr. 1036). Commenters also pointed to data collected by a trade 
association from its members (e.g., Document ID 2181, pp. 5-6, 7; 2371, 
Attachment 1, Appendix A; 3544, pp. 12-13; 3583, Tr. 2394; 3585, Tr. 
2905-2906; 3588, Tr. 3936-3938; 4197, pp. 1-6; 4198, pp. 1-181; 4223, 
pp. 68-70).
    The Agency, while including specific examples in the definition 
(i.e., air monitoring data from industry-wide surveys and calculations 
based on the composition of a substance), does not intend to limit the 
information that can be considered objective data to the information 
from those sources. OSHA agrees that data developed with alternative 
exposure measurement and characterization strategies, both those 
currently available and those that become available in the future, and 
the types of information and information sources suggested by 
commenters can be used as objective data where the conditions of the 
definition are satisfied. Monitoring data obtained prior to the 
effective date of the rule can also be considered objective data if it 
demonstrates employee exposure to respirable crystalline silica 
associated with a particular product or material or a specific process, 
task, or activity and reflects workplace conditions closely resembling 
or with a higher exposure potential than the processes, types of 
material, control methods, work practices, and environmental conditions 
in the employer's current operation.
    Objective data is further discussed in the summary and explanation 
of Scope

[[Page 16712]]

and Application (paragraph (a)(2) for general industry and maritime) 
and Exposure Assessment (paragraph (d) for general industry and 
maritime standard and paragraph (d)(2) for the construction standard).
    ``Physician or other licensed health care professional [PLHCP]'' 
means an individual whose legally permitted scope of practice (i.e., 
license, registration, or certification) allows him or her to 
independently provide or be delegated the responsibility to provide 
some or all of the particular health care services required by 
paragraph (i) of this section (paragraph (h) of the standard for 
construction). This definition is unchanged from the proposal, and is 
included because the standard requires that all medical examinations 
and procedures be performed by or under the supervision of a PLHCP.
    OSHA received two comments on the definition of PHLCP, both of 
which addressed the scope of the PHLCP's qualifications, from APHA and 
ATS (Document ID 2175, p. 5; 2178, Attachment 1, p. 5). ATS agreed with 
OSHA's determination of who is qualified to be a PLHCP (Document ID 
2175, p. 5). APHA advocated that the PLHCP:

. . . should be licensed for independent practice . . . and have 
training and experience in clinical and in population/preventive 
health, in managing and interpreting group surveillance information, 
and in the care and management of respiratory illness (Document ID 
2178, Attachment 1, p. 5).

APHA commented that:

. . . different members of the health team may provide different 
required services through referral or other arrangements, but the 
designated PLHCP should have responsibility for program oversight 
and coordination (Document ID 2178, Attachment 1, p. 5).

    As discussed further in the summary and explanation of Medical 
Surveillance, OSHA agrees that different tasks may be performed by 
various PLHCPs, according to their licenses, but has determined that 
requiring a license for independent practice and the extra training and 
responsibilities advocated by APHA are neither necessary nor 
appropriate for the PLHCP in OSHA standards. Any PLHCP may perform the 
medical examinations and procedures required under the standard when he 
or she is licensed, registered, or certified by state law to do so. Who 
qualifies to be a PLHCP is determined on a state-by-state basis by 
state licensing bodies. OSHA's broad definition for PLHCP gives the 
employer the flexibility to retain the services of a variety of 
qualified licensed health care professionals. Moreover, since the term 
PHLCP includes more than just physicians, it addresses concerns about 
the limited availability of medical providers in rural areas (e.g., 
Document ID 2116, Attachment 1, p. 43; 2365, p. 10).
    OSHA has included the same definition for PLHCP in other standards 
and continues to find that it is appropriate to allow any individual to 
perform medical examinations and procedures that must be made available 
under the standard when he or she is appropriately licensed by state 
law to do so and is therefore operating under his or her legal scope of 
practice. PLHCP, as defined and used in this standard, is consistent 
with other recent OSHA standards, such as chromium (VI) (29 CFR 
1910.1026), methylene chloride (29 CFR 1910.1052), and respiratory 
protection (29 CFR 1910.134). OSHA's experience with PLHCPs in these 
other standards supports the Agency's determination.
    ``Regulated Area'' means an area, demarcated by the employer, where 
an employee's exposure to airborne concentrations of respirable 
crystalline silica exceeds, or can reasonably be expected to exceed, 
the PEL. The definition is unchanged from the proposed standard. This 
definition is consistent with the use of the term in other OSHA 
standards, including those for chromium (VI) (29 CFR 1910.1026), 1,3-
butadiene (29 CFR 1910.1051), and methylene chloride (29 CFR 
1910.1052).
    OSHA proposed the inclusion of regulated areas in the standards for 
both construction and general industry/maritime, but has not included 
this provision, or the associated definition, in the final standard for 
construction. Construction industry stakeholders should instead refer 
to paragraph (g)(1)(iv) for written exposure control plan requirements 
to describe procedures for restricting access.
    Several stakeholders, including the Construction Industry Safety 
Coalition (CISC) and National Association of Home Builders, requested 
that OSHA clarify what ``reasonably expected'' means (e.g., Document ID 
2296, p. 25; 2319, p. 89). CISC argued that ``[s]uch subjective 
language is not enforceable and . . . will be fraught with compliance 
problems . . .'' (Document ID 2296, p. 25; 2319, p. 89).
    As noted above, the language in the regulated areas definition has 
been included in a number of previous OSHA standards. Based on OSHA's 
experience with these standards, OSHA expects that employers will have 
little difficulty understanding the meaning of the phrase ``reasonably 
be expected to exceed.'' One reason OSHA chooses to utilize language 
that has been used in previous standards, where possible, is to avoid 
the sort of confusion CISC describes. In addition, the basis for 
establishing regulated areas in general industry and maritime and the 
reason for omitting this requirement in the construction standard are 
discussed in further detail in the summary and explanation of Regulated 
Areas.
    ``Respirable crystalline silica'' means quartz, cristobalite, and/
or tridymite contained in airborne particles that are determined to be 
respirable by a sampling device designed to meet the characteristics 
for respirable-particle-size-selective samplers specified in the 
International Organization for Standardization (ISO) 7708:1995: Air 
Quality--Particle Size Fraction Definitions for Health-Related 
Sampling. The definition in the rule is very similar to the proposed 
definition with one modification. OSHA changed the wording from ``means 
airborne particles that contain quartz, cristobalite, and/or tridymite 
and whose measurement is determined by a sampling device . . .'' to 
``means quartz, cristobalite, and/or tridymite contained in airborne 
particles that are determined to be respirable by a sampling device . . 
.'' to make it clear that only that portion of the particles that is 
composed of quartz, cristobalite, and/or tridymite is considered to be 
respirable crystalline silica.
    The definition for respirable crystalline silica encompasses the 
forms of silica (i.e., quartz, cristobalite, and tridymite) covered 
under current OSHA standards and harmonizes the Agency's practice with 
current aerosol science and the international consensus that the ISO 
convention represents. The American Conference of Governmental 
Industrial Hygienists (ACGIH) and the European Committee for 
Standardization (CEN) have adopted the ISO criteria for respirable 
particulate collection efficiency, and the criteria are sometimes 
referred to as the ISO/CEN definition. NIOSH has also adopted the ISO 
definition in its Manual of Sampling and Analytical Methods (Document 
ID 0903, p. 2). Adoption of this definition by OSHA allows for 
workplace sampling for respirable crystalline silica exposures to be 
conducted using any particulate sampling device that conforms to the 
ISO criteria (i.e., a device that collects dust according to the 
particle collection efficiency curve specified in the ISO standard). 
The relationship between the ISO criteria for respirable particulate 
collection efficiency and the ACGIH criteria is discussed in greater 
detail in

[[Page 16713]]

the Sampling and Analysis discussion in Chapter IV of the FEA.
    The U.S. Chamber of Commerce (the Chamber), Halliburton, and the 
National Rural Electric Cooperative Association (NRECA) asserted that 
OSHA's proposed definition of respirable crystalline silica would 
encompass non-respirable particles (Document ID 2288, p. 15; 2302, p. 
7; 2365, p. 12). NRECA stated:

. . . the proposed definition would include anything that gets 
collected onto the sampling media from respirable-particle size-
selective samplers. Unfortunately, these samplers are not fool-proof 
and often much larger sized particles do make their way into the 
sampling media; that is, they collect total crystalline silica dusts 
rather than just the respirable portions. This definition will 
include all total dusts that make their way through the cyclone and 
into the sampling media, thus suggesting a much larger exposure than 
is otherwise the case . . . (Document ID 2365, p. 12).

    As indicated in the discussion of the feasibility of measuring 
respirable crystalline silica exposures in Chapter IV of the FEA, there 
is currently no sampling device that precisely matches the ISO criteria 
in capturing respirable dust. However, available research indicates 
that many existing devices can achieve good agreement with the ISO 
criteria. When operated correctly, the sampling devices do not collect 
total dusts; they collect only the respirable fraction.
    The Chamber and NRECA also argued that OSHA's proposed definition 
of respirable crystalline silica would include substances other than 
crystalline silica (Document ID 2288, p. 15; 2365, p. 12; 3578, Tr. 
1138). NRECA stated:

    An additional concern with the definition is that it states 
``any particles that contain quartz, cristobalite, and/or tridymite 
. . .'' It is possible to interpret this portion of the definition 
to mean that any other mineral/impurities that were able to be 
collected into the sampling media will be counted/weighed as opposed 
to just the silica portions . . . (Document ID 2365, p. 12).

In addition, American Industrial Hygiene Association (AIHA) indicated 
that the proposed definition would include the entirety of a sample of 
dust containing any miniscule but detectable quantity of quartz, 
cristobalite or tridymite, and recommended revising the definition 
(Document ID 2169, pp. 2-3).
    OSHA recognizes that the proposed definition could have been 
misunderstood to encompass components of respirable dust particles 
other than quartz, cristobalite, and tridymite. This was not the 
Agency's intent, and, in response to these comments, OSHA has revised 
the definition to clarify that only the portion of the particles 
composed of quartz, cristobalite, or tridymite is considered to be 
included in the definition of respirable crystalline silica.
    Ameren Corporation supported OSHA's inclusion of quartz and 
cristobalite and allowing the use of a sampling device designed to meet 
the characteristics for respirable particle size-selective samplers 
specified in ISO 7708:1995 in the definition, but indicated that the 
definition should be limited to a ``percentage of 1% or greater'' 
(Document ID 2315, p. 3). However, it did not provide a rationale for 
why OSHA should include this in the definition. Including such a 
limitation in the definition of respirable crystalline silica would 
have the effect of limiting coverage of the rule to situations where 
crystalline silica concentrations in a mixture exceed the 1 percent 
threshold. As discussed in the summary and explanation of Scope and 
Application, OSHA concludes that it is not appropriate to limit 
coverage of the rule to situations where concentrations of crystalline 
silica in a mixture exceed a 1 percent threshold.
    The Society for Protective Coatings (SSPC) and the National 
Automobile Dealers Association recommended that OSHA distinguish 
between amorphous silica and crystalline silica in the definition 
(Document ID 2120, p. 2; 2358, p. 5). SSPC also provided a link to a 
Web page (http://www.crystallinesilica.eu/content/what-respirable-crystalline-silica-rcs) to guide the Agency on revising the definition. 
OSHA finds that the term ``crystalline'' is sufficiently descriptive 
and does not merit further explanation in the definition. However, the 
Agency affirms here that fused quartz and other forms of amorphous 
silica are not considered crystalline silica under the rule.
    The SEFA Group (formerly the Southeastern Fly Ash Company) 
suggested adding a definition for ``free respirable crystalline 
silica'' to describe crystalline silica as an independent structure 
with varying surface chemistry, as distinguished from crystalline 
silica that is incorporated into a larger matrix of the parent mineral 
(Document ID 2123, p. 2). OSHA has revised the definition to clarify 
that respirable crystalline silica includes only the crystalline silica 
contained in airborne particles, i.e., the component in dust that is 
crystalline silica and not some other mineral. The Agency does not 
agree that defining the term ``free respirable crystalline silica'' 
will alter the meaning or enhance the clarity of the rule, and has not 
added this term.
    ``Specialist'' means an American Board Certified Specialist in 
Pulmonary Disease or an American Board Certified Specialist in 
Occupational Medicine. The term is used in paragraph (i) of the 
standard for general industry and maritime, (paragraph (h) of the 
standard for construction), which sets forth requirements for medical 
surveillance. For example, paragraph (i)(7)(i) of the standard for 
general industry and maritime, (paragraph (h)(7)(i) of the standard for 
construction) requires that the employer make available a medical 
examination when specialist referral is indicated in the PLHCP's 
written medical opinion for the employer.
    The proposed rule did not include this term in the Definitions 
paragraph because it only allowed referral to an American Board 
Certified Specialist in Pulmonary disease, which was clearly addressed 
in the Medical Surveillance paragraph of the rule. However, several 
commenters recommended that OSHA expand the types of specialists to 
whom employees could be referred. For example, Dow Chemical requested 
that OSHA not require the pulmonary specialist to be board certified to 
expand availability of specialists and noted that several OSHA 
standards, such as benzene and 1,3-butadiene, do not require the 
specialist to be board certified (Document ID 2270, pp. 5-8). The Glass 
Association of America, Asphalt Roofing Manufacturers Association, 
North American Insulation Manufacturers Association, ATS, and BCTD 
requested that OSHA also allow referral to an occupational medicine 
specialist, with many of them specifying a board certified occupational 
medicine specialist (Document ID 2215, p. 9; 2291, p. 26; 2348, 
Attachment 1, p. 40; 3577, Tr. 778; 4223, p. 129).
    OSHA is retaining the requirement for board certification to ensure 
a high level of competency. However, OSHA is persuaded by comments and 
testimony that individuals who are either American Board Certified in 
Occupational Medicine or American Board Certified in Pulmonary Disease 
are recognized specialists qualified to examine patients referred for 
possible respirable crystalline silica-related diseases. OSHA concludes 
that both pulmonary disease and occupational medicine specialists are 
qualified to counsel employees regarding work practices and personal 
habits that could affect their respiratory health, consistent with 
recommendations in Section 4.7.2 in ASTM standards E 1132-06, Standard 
Practice for Health Requirements Relating to Occupational

[[Page 16714]]

Exposure to Respirable Crystalline Silica and E 2626-09, Standard 
Practice for Health Requirements Relating to Occupational Exposure to 
Respirable Crystalline Silica for Construction and Demolition 
Activities (Document ID 1466, p. 5; 1504, p. 5). OSHA therefore added 
the definition to allow referrals to providers who are American Board 
certified in pulmonary disease or occupational medicine. The addition 
of the term to definitions also allows OSHA to simply refer to 
``specialist'' when referring to American Board certified pulmonary 
disease and occupational medicine specialists in the medical 
surveillance paragraph of the rule.
    ``Assistant Secretary,'' ``Director,'' and ``This section'' are 
also defined terms. The definitions are consistent with OSHA's previous 
use of these terms in other health standards and have not changed since 
the proposal, which elicited no comments.
    Finally, stakeholders suggested that OSHA define a number of new 
terms, including: ``affected employee'' (American Iron and Steel 
Institute (AISI) (Document ID 2261, p. 4)), ``aged silica'' (the 
Sorptive Minerals Institute (Document ID 3587, Tr. 3698-3699)), 
``asphalt milling'' (IUOE (Document ID 2262, pp. 23-24)), ``chest 
radiograph'' (NIOSH (Document ID 2177, Comment B, pp. 40-41)), 
``controlling employer'' (BAC and BCTD (Document ID 2329, p. 7; 2371, 
pp. 38-40)), ``each employee'' or ``each affected employee'' (AISI 
(Document ID 3492, p. 3)), ``earth moving'' (IUOE (Document ID 2262, 
pp. 6-9, 15)), ``earth moving equipment'' (IUOE (Document ID 3583, Tr. 
2356-2360; 2262, pp. 6-9, 15)), ``estimating respirable dust, 
excessive'' (Industrial Hygiene Specialty Resources (Document ID 2285, 
p. 7)), ``gross contamination'' or ``grossly contaminated'' (ORCHSE, 
AFS, and NAHB (Document ID 2277, p. 4; 3584, Tr. 2669-2671; 3487, pp. 
21-22; 2296, p. 29; 2379, Attachment B, p. 32)), ``grossly'' (Tile 
Council of North America (Document ID 2363, p. 6)), ``intermittent 
work'' (EEI (Document ID 2357, p. 14)), ``respirable dust'' (AFS 
(Document ID 2379, Attachment B, pp. 16, 28)), ``safety and health 
professional technician'' (Dr. Bird of the Chamber (Document ID 3578, 
Tr. 1176-1177)), ``short duration'' (EEI (Document ID 2357, p. 14)), 
and ``silica exposure'' (AIHA (Document ID 2169, p. 5)).
    OSHA has concluded that these terms do not need to be defined in 
the rule. Many of the terms were part of the proposal or were included 
in stakeholder's comments on the proposal, but do not appear in the 
rule. For example, the proposed rule contained a provision related to 
protective work clothing in regulated areas that would have been 
triggered where there is potential for employees' work clothing to 
become grossly contaminated with finely divided material containing 
crystalline silica. As discussed in summary and explanation of 
Regulated Areas, OSHA has not included a requirement for employers to 
provide protective work clothing or other means of removing silica dust 
from clothing in the rule, and the rule does not otherwise use the 
terms ``grossly,'' ``gross contamination,'' or ``grossly 
contaminated.'' Therefore, there is no reason to define these terms.
    OSHA concludes that many of the other terms that stakeholders asked 
the Agency to define are sufficiently explained in the preamble or 
their meanings are clear. For example, OSHA explains the term 
``affected employee'' in the summary and explanation of Exposure 
Assessment. Because the term only appears in paragraphs (d)(6) and (7) 
of the standard for general industry and maritime (paragraphs 
(d)(2)(vi) and (vii) for construction) and is thoroughly explained in 
the summary and explanation, OSHA concludes that it need not be defined 
in this section.
    Specified Exposure Control Methods. OSHA's standard requires 
employers engaged in construction to control their employees' exposure 
to respirable crystalline silica. Paragraph (c) of the standard for 
construction describes the specified exposure control methods approach. 
This approach includes ``Table 1: Specified Exposure Control Methods 
When Working With Materials Containing Crystalline Silica,'' a table 
identifying common construction tasks known to generate high exposures 
to respirable crystalline silica and specifying appropriate and 
effective engineering controls, work practices, and respiratory 
protection for each identified task. For each employee engaged in a 
task identified on Table 1, the employer is required to fully and 
properly implement the engineering controls, work practices, and 
respiratory protection specified for the task on Table 1, unless the 
employer assesses and limits the exposure of the employee to respirable 
crystalline silica in accordance with paragraph (d) of the standard for 
construction. If the employer fully and properly implements the 
engineering controls, work practices, and respiratory protection 
specified for each employee engaged in a task identified on Table 1, 
the employer is not required to conduct exposure assessments or 
otherwise comply with a PEL for those employees. If the employer does 
not follow Table 1 for employees engaged in identified tasks or if the 
respirable crystalline silica-generating task is not identified on 
Table 1, the employer must assess and limit the exposure of employees 
in accordance with paragraph (d) of the standard for construction. 
Paragraph (d) of the standard for construction imposes requirements 
similar to OSHA's traditional approach of requiring employers to 
demonstrate compliance with a PEL through required exposure assessments 
and controlling employee exposures through the use of feasible 
engineering controls and work practices (i.e., the hierarchy of 
controls) (see the summary and explanation of Alternative Exposure 
Control Methods for further discussion of this approach).
    The concept for the specified exposure control methods approach was 
included in the proposed rule. OSHA also included a version of Table 1 
in the proposed rule for construction employers, identifying specific 
engineering controls, work practices, and respiratory protection for 
common construction tasks that employers could use to meet the 
requirement to implement engineering and work practice controls. 
Employers fully implementing the engineering controls, work practices, 
and respiratory protection on Table 1 would not have been required to 
conduct exposure assessments for employees performing a listed task, 
but would have been required to comply with the 50 [micro]g/m\3\ PEL 
for those employees. For tasks where respirator use was to be required, 
employees were presumed to be exposed above the PEL, and thus the 
proposed standard would have required the employer to comply with all 
provisions that would be triggered by exposure above the PEL (e.g., 
regulated areas, medical surveillance), except for exposure monitoring.
    Prior to the NPRM, OSHA included this alternative compliance 
approach in the Preliminary Initial Regulatory Flexibility Analysis 
(PIRFA) provided to small business representatives during the Small 
Business Regulatory Enforcement Fairness Act (SBREFA) process (Document 
ID 0938, pp. 16-17). Participants in the SBREFA process generally 
supported the approach and their comments further informed the Agency 
in developing the proposed rule (Document ID 0937, pp. 37-39). An 
alternative compliance approach similar to that developed by OSHA for 
the SBREFA process was also included in ASTM E 2625-09, Standard 
Practice for Controlling Occupational Exposure to Respirable 
Crystalline Silica for Construction and Demolition Activities, a 
consensus standard issued in May

[[Page 16715]]

2009 developed by a committee consisting of both labor and industry 
representatives for crystalline silica exposures in construction 
(Document ID 1504). Following this, on December 10, 2009, the Advisory 
Committee on Construction Safety and Health (ACCSH) recommended that 
OSHA include the specified exposure control methods approach in its 
proposed rule (Document ID 1500, p. 13).
    The approach of specifying a list of tasks with a corresponding 
list of controls to simplify compliance in the construction industry 
received wide support from representatives in government, including the 
National Institute for Occupational Safety and Health (NIOSH); 
professional organizations, including the American Industrial Hygiene 
Association (AIHA) and the American Society of Safety Engineers (ASSE); 
labor, including the International Union of Operating Engineers (IUOE), 
the Building and Construction Trades Department of the AFL-CIO (BCTD), 
the Laborers' Health and Safety Fund of North America (LHSFNA), and the 
International Union of Bricklayers and Allied Craftworkers (BAC); and 
industry groups, including the Associated General Contractors of New 
York State, the Edison Electric Institute (EEI), and the National 
Asphalt Pavement Association (NAPA) (e.g., Document ID 2177, Attachment 
B, p. 23; 3578, Tr. 1028; 2339, p. 8; 3583, Tr. 2337-2338; 2371, 
Attachment 1, p. 22-23; 3589, Tr. 4192-4193; 2329, pp. 5-6; 2145, pp. 
4-5; 3583, Tr. 2171; 2357, p. 26). Walter Jones, an industrial 
hygienist representing LHSFNA, testified that the approach ``not only 
makes compliance . . . easier to determine, enforce, and teach, it also 
assures acceptable levels of healthfulness'' (Document ID 3589, Tr. 
4193).
    Industry trade associations, such as the Construction Industry 
Safety Coalition (CISC), Leading Builders of America (LBA), the 
Mechanical Contractors Association of America, and individual 
construction employers, including Atlantic Concrete Cutting, Inc. and 
Holes Incorporated, generally supported the overall approach while 
being critical of the specifics of Table 1 (e.g., Document ID 4217, p. 
20; 2367, p. 2; 2338, p. 3; 2269, pp. 21-22; 2143, pp. 2-3). CISC 
stated that its group of employers ``continues to be appreciative of 
OSHA's efforts to try to make a simple compliance option . . . for 
construction employers'' (Document ID 4217, p. 20).
    One commenter, Francisco Trujillo, safety director for Miller and 
Long, Inc., suggested that the specified exposure control methods 
approach to compliance in the construction industry is not a substitute 
for safety professionals and industrial hygienists conducting exposure 
assessments and selecting the appropriate engineering controls, work 
practices, and respiratory protection for each task based on the 
results. He commented that ``[t]he implication that if Table 1 is 
followed everything will be fine is unrealistic . . .'' and recommended 
that Table 1 be at most non-mandatory guidance (Document ID 2345, p. 
4).
    OSHA agrees that safety professionals and industrial hygienists 
play a key role in ensuring the safety of employees exposed to silica 
during certain activities, including those not listed on Table 1, and 
can also help ensure that the engineering controls, work practices, and 
respiratory protection specified on Table 1 are fully and properly 
implemented. However, as discussed below, the Agency is not persuaded 
that construction employees will always be better protected by the 
traditional performance approach of establishing a PEL and requiring 
periodic exposure assessments, particularly when the tasks and tools 
that cause high exposures to respirable crystalline silica, and the 
dust control technologies available to address such exposures, can be 
readily identified.
    Although there was general agreement among commenters that an 
alternative approach was needed to simplify compliance for the 
construction industry, commenters provided various opinions on how such 
an alternative compliance approach should be structured to ensure that 
it was workable in practice. Several commenters, including BCTD, 
LHSFNA, EEI, LBA, Fann Contracting, Inc., CISC, ASSE, the National 
Association of Home Builders (NAHB), the Associated Builders and 
Contractors (ABC), and Holes Incorporated, urged OSHA to exempt 
employers complying with Table 1 from also complying with the PEL 
(e.g., Document ID 2371, Attachment 1, p. 26; 4223, p. 92-94; 4207, p. 
3; 2357, p. 26; 2269, pp. 21-22; 2116, Attachment 1, p. 29; 2319, pp. 
123-124; 2339, pp. 8-9; 2296, p. 41; 2289, p. 7; 3580, Tr. 1364). Holes 
Incorporated and ABC suggested that employers would not use an approach 
that required compliance with both the PEL and specified engineering 
controls (Document ID 3580, Tr. 1364; 2289, p. 7). The National Utility 
Contractors Association (NUCA) argued that not linking the actions on 
Table 1 directly to compliance with the regulation was confusing and 
would make it difficult for contactors to be certain they are in 
compliance (Document ID 2171, p. 2). ASSE suggested that Table 1 should 
constitute compliance with the PEL because the listed controls ``can be 
viewed as akin to implementing all technologically feasible controls'' 
(Document ID 2339, pp. 8-9). BCTD commented that the focus of OSHA's 
enforcement efforts should be on ensuring that employers have fully and 
properly implemented the controls listed on Table 1 (Document ID 2371, 
Attachment 1, p. 26).
    Similarly, commenters from both industry and labor, including the 
American Federation of State, County, and Municipal Employees, 
Mechanical Contractors Association of America, the American Federation 
of Labor and Congress of Industrial Organizations, BAC, BCTD, and 
LHSFNA, also argued that exposure assessments should not be required 
where employers implement control measures specified on Table 1 for 
construction tasks (e.g., Document ID 2106, p. 3; 2143, pp. 2-3; 2256, 
Attachment 2, p. 10; 2329, pp. 5-6; 2371, Attachment 1, pp. 6-7; 4207, 
p. 2). LHSFNA stated that:

. . . air monitoring is less practical in construction, where the 
jobsite and work is constantly changing, than in general industry 
where work exposures are more stable. In construction, air 
monitoring results often come back from the lab after the task has 
ended and thus are of little value . . . (Document ID 2253, p. 2).

    On the other hand, other commenters, including NIOSH, argued that 
fully implementing the controls described on Table 1 would not 
automatically provide a sufficient level of confidence that exposures 
are adequately controlled; employers would also need to ensure that the 
exposures of employees performing Table 1 tasks would not exceed the 
revised PEL (e.g., Document ID 2177, Attachment B, p. 17). Mr. 
Trujillo's comment emphasizing the role of safety professionals and 
recommending that Table 1 be at most non-mandatory guidance was to the 
same effect (Document ID 2345, p. 4).
    Several commenters, including Fann Contracting, IUOE, LBA, CISC, 
Charles Gordon, a retired occupational safety and health attorney, Arch 
Masonry, Inc., and NUCA argued that as proposed, the alternative 
compliance option would not necessarily simplify compliance for some 
employers, as they would still need to do exposure assessments for a 
variety of reasons, such as monitoring employees working in the 
vicinity of Table 1 tasks, complying with the PEL, providing monitoring 
data to controlling employers on multi-employer worksites, and 
complying with the rule for tasks

[[Page 16716]]

that are not listed on Table 1 (Document ID 2116, Attachment 1, p. 3; 
2262, pp. 44-45; 2269, pp. 21-22; 2319, p. 6; 3538, p. 16; 3580, Tr. 
1473-1474; 3587, Tr. 3677-3679; 3583, Tr. 2243).
    Other commenters supported the inclusion of exposure assessment 
requirements for employees performing tasks on Table 1 even where 
employers implement the specified engineering controls, work practices, 
and respiratory protection to best protect employees in the 
construction industry. The Center for Progressive Reform commented 
that:

[t]he same principles that weigh in favor of a requirement to 
monitor silica exposure in other industries holds for the 
construction industry--monitoring gives workers, employers, OSHA, 
and researchers valuable information that can be used to reduce 
workplace hazards (Document ID 2351, p. 11).

    The International Safety Equipment Association (ISEA) opined that 
the most protective approach for employees is for employers to take air 
samples of respirable crystalline silica (Document ID 2212, p. 1). AIHA 
argued that there remained a need for exposure monitoring to verify 
that the controls in place for Table 1 tasks actually reduce exposures 
(Document ID 2169, p. 3). NIOSH recommended periodic exposure 
monitoring requirements for these tasks to provide a sufficient level 
of confidence that exposures are adequately controlled and that the 
employers' selection of equipment, maintenance practices, and employee 
training were effective (Document ID 2177, Attachment B, pp. 17, 26). 
Charles Gordon proposed that when performing a Table 1 task, employers 
should be required to semi-annually monitor each task and keep records 
of that monitoring to ensure that workers are not exposed to high 
levels of respirable crystalline silica (Document ID 3539; 3588, Tr. 
3801).
    After reviewing the comments on this issue, OSHA concludes that the 
best approach for protecting employees exposed to respirable 
crystalline silica in the construction industry is to provide a set of 
effective, easy to understand, and readily implemented controls for the 
common equipment and tasks that are the predominant sources of exposure 
to respirable crystalline silica. OSHA is persuaded by comments and 
data in the record that requiring specific engineering controls, work 
practices, and respiratory protection for construction tasks, in lieu 
of a performance-oriented approach involving a PEL and exposure 
assessment, is justified for several reasons so long as employers fully 
and properly implement the engineering controls, work practices, and 
respiratory protection specified on Table 1.
    First, the controls listed on Table 1 represent the feasible 
controls identified in the record for each listed task, and there is 
substantial evidence that demonstrates that, for most of the Table 1 
tasks, exposure to respirable crystalline silica can be consistently 
controlled below 50 [micro]g/m\3\ using those controls (see Chapter IV 
of the Final Economic and Regulatory Flexibility Analysis (FEA)). As 
such, Table 1 provides a less burdensome means of achieving protection 
at least equivalent to that provided by the alternative exposure 
control methods that include the 50 [micro]g/m\3\ PEL, which OSHA has 
determined to be the lowest feasible exposure level that could be 
achieved most of the time for most of the tasks listed on Table 1. For 
example, as discussed in Section 5.7 of Chapter IV of the FEA, exposure 
data demonstrates that the engineering controls and work practices 
specified on Table 1 for stationary masonry saws (wet cutting) 
significantly reduce employees' exposures to respirable crystalline 
silica from a mean of 329 [micro]g/m\3\, when cutting masonry dry, to a 
mean of 41 [micro]g/m\3\. Additionally, the record developed during the 
rulemaking process has contributed greatly to the Agency's 
understanding of the effectiveness of the prescribed controls. Based on 
the record, OSHA is confident that exposures will be adequately 
controlled using the specified methods supplemented with appropriate 
respiratory protection for those few tasks that are very difficult to 
control using engineering controls and work practices alone.
    Second, this approach recognizes and avoids the challenges of 
characterizing employee exposures to crystalline silica accurately in 
many construction tasks while also ensuring that employees are 
protected. In manufacturing settings and other more stable environments 
subject to the general industry standard, exposure assessment can 
provide an accurate depiction of the silica exposure that could be 
typically expected for employees in normal operating conditions. In 
general, such assessments need not be repeated frequently, costs are 
therefore minimized, and the results will be timely even if there is a 
delay for lab processing. In contrast, the frequent changes in 
workplace conditions that are common in construction work (e.g., 
environment, location), along with potential time-lags in the exposure 
assessment process, provide a compelling argument for the specified 
exposure control methods approach that emphasizes clear and timely 
guidance capable of protecting the employees during their shifts 
instead of relying on a minimum exposure assessment requirement to 
characterize employee exposures.
    Third, requiring employers to implement specified dust controls 
absent an additional PEL requirement simplifies compliance for 
employers who fully and properly implement the engineering controls, 
work practices, and respiratory protection listed on Table 1. 
Simplifying compliance will also encourage employers performing tasks 
listed on Table 1 to use this approach, rather than the alternative of 
performing exposure assessments and implementing dust controls, as 
required by paragraph (d) of the standard for construction, and thus, 
will also reduce regulatory burden on construction employers of all 
sizes. For this reason, OSHA expects that the vast majority of 
construction employers will choose to follow Table 1 for all Table 1 
tasks.
    Fourth, this approach will also create greater awareness of 
appropriate controls, which may in turn facilitate better 
implementation and compliance, by making it far easier for employees to 
understand what controls are effective for a given task and what 
controls the employer must provide. Employees can locate the task they 
are performing on Table 1 and immediately see what controls are 
required, along with any specifications for those controls. It will, 
further, be clear if an employer is not providing the correct controls 
or ensuring that they are being used appropriately.
    ``Fully and properly'' implementing the specified exposure control 
methods. In order for employers to comply with paragraph (c) of the 
standard for construction, they must ``fully and properly'' implement 
the engineering controls, work practices, and respiratory protection 
for each employee engaged in a task identified on Table 1. While 
several commenters, including BAC and BCTD, supported this requirement 
(e.g., Document ID 2329, p. 6; 2371, Attachment 1, p. 24), BCTD also 
urged OSHA to clarify the meaning of ``fully and properly'' 
implementing the specified engineering controls and work practices on 
Table 1 to ensure that employers know what is required of them and how 
the standard will be enforced (Document ID 4223, p. 92; 2371, 
Attachment 1, p. 27-29).
    Other commenters provided suggestions for what they believed should 
be considered ``fully and properly implementing'' the controls 
specified on Table 1. NIOSH recommended that OSHA provide checklists 
and require a daily evaluation

[[Page 16717]]

of engineering controls to determine if the controls are performing as 
designed and to ensure that employees using the controls are trained 
and have the appropriate materials to operate the controls properly 
(Document ID 2177, Attachment B, pp. 21-22). IUOE recommended that 
regular inspections of engineering controls in enclosed cabs should be 
required (Document ID 2262, p. 29). Anthony Bodway, Special Projects 
Manager at Payne & Dolan, Inc., representing NAPA, testified that his 
paving company uses a daily maintenance checklist to ensure that the 
controls are functioning properly and meeting the standards set by the 
equipment manufacturers (Document ID 3583, Tr. 2194-2197). AIHA 
suggested that OSHA require employers to follow the manufacturer's user 
instructions for installation, use, and maintenance of engineering 
controls, unless there is a written variance from the manufacturer 
(Document ID 2169, p. 5). Charles Gordon argued that OSHA should 
require a competent person to evaluate the use of the controls 
specified on Table 1 initially and periodically in order to ensure that 
they are fully and properly implemented (Document ID 4236, p. 4). In 
general disagreement with these comments, the National Stone, Sand, and 
Gravel Association (NSSGA) argued that, while employers should conduct 
routine maintenance of the controls, OSHA should not require an 
employer to complete an evaluation or inspection checklist of controls 
or work practices at a certain frequency (Document ID 2327, Attachment 
1, p. 21).
    Although the specified exposure control methods approach affords 
compliance flexibility for the employer, OSHA sees value in reminding 
employers and employees that this option will only be protective if 
they take steps to ensure that the engineering controls, work 
practices, and respiratory protection are as effective as possible. 
Thus, the Agency is requiring employers to fully and properly implement 
the specified engineering controls, work practices, and respiratory 
protection for each employee performing a task described on Table 1 in 
order to be in compliance with paragraph (c)(1) of the standard for 
construction. To do otherwise would undermine the entire basis for this 
compliance approach.
    Merely having the specified controls present is not sufficient to 
constitute ``fully and properly'' implementing those controls. 
Employees will not be protected from exposure to respirable crystalline 
silica if the specified engineering controls, work practices, and 
respiratory protection are not also implemented effectively. In order 
to be in compliance with paragraph (c)(1) of the standard for 
construction, employers are required to ensure that the controls are 
present and maintained and that employees understand the proper use of 
those controls and use them accordingly.
    While OSHA has decided not to further define ``fully and properly'' 
by providing specific checklists for employers or requiring employers 
to conduct inspections at set intervals, there are several readily 
identifiable indicators that dust controls are or are not being fully 
and properly implemented, many of which are discussed with regard to 
specific equipment and tasks in Chapter IV of the FEA and in the 
discussions of specific controls that appear further below in the 
section. For example, for dust collection systems, the shroud or 
cowling must be intact and installed in accordance with the 
manufacturer's instructions; the hose connecting the tool to the vacuum 
must be intact and without kinks or tight bends that would prevent the 
vacuum from providing the air flow recommended by the tool 
manufacturer; the filter(s) on the vacuum must be cleaned or changed as 
frequently as necessary in order to ensure they remain effective (it 
may be necessary to activate a back-pulse filter cleaning mechanism 
several times during the course of a shift); and dust collection bags 
must be emptied as frequently as necessary to avoid overfilling, which 
would inhibit the vacuum system from operating effectively. For water-
based dust suppression systems, an adequate supply of water for dust 
suppression must be available on site. For worksites without access to 
a water main, a portable water tank or water truck having enough water 
for the task must be provided. The spray nozzles must be working 
properly to produce a spray pattern that applies water at the point of 
dust generation and inspected at regular intervals to ensure they are 
not clogged or damaged. All hoses and connections must be inspected as 
necessary for leaks that could signal that an inadequate flow rate is 
being delivered.
    Manufacturer's instructions can also provide information about how 
to fully and properly implement and maintain controls. For example, the 
operator's instruction manual for EDCO concrete/asphalt saws provides a 
pre-start checklist that includes information about the proper 
functioning of wet-cutting equipment (Document ID 1676, p. 5). In some 
cases, industry associations and employers, in collaboration with 
equipment manufacturers, have also developed best practices with regard 
to the full and proper implementation of engineering controls, work 
practices, and respiratory protection for their particular industry or 
operation. For example, NAPA and the Association of Equipment 
Manufacturers (AEM) provided operational guidance for water systems 
during milling operations that includes pre-operation inspection 
activities, preparations for safe operation, and other operation 
considerations (Document ID 2181, p. 52).
    In addition, paragraph (g) of the standard for construction 
requires employers to establish and implement a written exposure 
control plan, which includes provisions for a competent person to make 
frequent and regular inspection of job sites, materials, and equipment 
in order to implement the plan (see the summary and explanation of 
Written Exposure Control Plan for discussion about this requirement). 
Thus, the requirement for a written exposure control plan and the 
competent person, which was added to the final standard for 
construction, provides additional safeguards for ensuring that 
employers fully and properly implement Table 1.
    OSHA expects that in most instances it will be straightforward for 
a designated competent person to identify whether the controls have 
been fully and properly implemented. For example, a significant amount 
of visible dust being frequently or continuously emitted from the 
material being worked on can serve as an indication that controls are 
not fully and properly implemented. A small amount of dust can be 
expected even with new equipment that is operating as intended by the 
manufacturer. The amount of visible dust associated with the new dust 
controls should be noted when equipment is put into service and checked 
periodically. A noticeable increase in dust emissions would indicate 
that the dust control system is not operating as intended.
    Employees engaged in Table 1 tasks. Commenters expressed concerns 
about the lack of requirements in the proposed rule to protect 
employees assisting with Table 1 tasks or working in the vicinity of 
others engaged in Table 1 tasks (e.g., Document ID 2116, Attachment 1, 
pp. 2-3). In response, OSHA has clarified the language in paragraph 
(c)(1) of the standard for construction to encompass all employees 
``engaged in a task identified on Table 1.'' This phrasing is intended 
to include not only the equipment operator, but also laborers and other 
employees who are assisting with the task or have some

[[Page 16718]]

responsibility for the completion of the task, even if they are not 
directly operating the equipment. For example, where an employee is 
assisting another employee operating a walk-behind saw indoors by 
guiding the saw and making sure that the cutting is precise, that 
employee would be considered to be engaged in the task and would need 
to wear a respirator. Similarly, employees assisting a jackhammer task 
would be considered to be engaged in the task and would also be 
required to wear a respirator if they engaged in the task outdoors for 
more than four hours in a work shift.
    It is not OSHA's intent, however, for all employees who are in the 
vicinity of a listed task to be considered ``engaged in the task.'' To 
protect the other employees in the vicinity of a listed task, the 
employer must account for the potential exposures of these employees to 
respirable crystalline silica as part of its written exposure control 
plan. As discussed in the summary and explanation of Written Exposure 
Control Plan, paragraph (g)(1)(iv) of the standard for construction 
requires a description of the procedures used to restrict access to 
work areas, when necessary, to limit the number of employees exposed 
and their exposure levels. Employers must develop procedures to 
restrict or limit access when employees in the vicinity of silica-
generating tasks are exposed to excessive respirable crystalline silica 
levels. Such a situation might occur in a variety of circumstances, 
including when an employee who is not engaged in the task, but is 
working in the vicinity of another employee performing a Table 1 task 
requiring respiratory protection, is exposed to clearly visible dust 
emissions (e.g., an employee directing traffic around another employee 
jackhammering for more than four hours in a shift). In that case, the 
competent person, as required under paragraph (g)(4) of the standard 
for construction, would assess the situation in accordance with the 
employer's procedures to determine if it presents a recognized hazard, 
and if it does, take immediate and effective steps to protect employees 
by implementing the procedures described in the written exposure 
control plan. For the above example, this could include positioning the 
employee directing traffic at a safe distance upwind from the dust-
generating activity.
    Table 1. As discussed above, paragraph (c)(1) of the standard for 
construction includes ``Table 1: Specified Exposure Control Methods 
When Working With Materials Containing Crystalline Silica,'' which 
identifies 18 common construction equipment/tasks known to generate 
high exposures to respirable crystalline silica. For each equipment/
task identified, Table 1 specifies appropriate and effective 
engineering and work practice control methods. Some entries contain 
multiple engineering controls and work practices. In those instances, 
OSHA has determined that the specified combination of engineering 
controls and work practices is necessary for reducing exposures and 
requires employers to implement all of the listed engineering controls 
and work practices in order to be in compliance. Some entries contain 
multiple compliance options denoted with an ``OR'' (e.g., (c)(1)(ix), 
(c)(1)(x), (c)(1)(xii), (c)(1)(xiii), (c)(1)(xv), and (c)(1)(xviii) of 
the standard for construction). For those entries, OSHA has determined 
that more than one control strategy could effectively reduce exposures 
and permits the employer to decide which option could be best 
implemented on the worksite. Table 1 also specifies respiratory 
protection for those entries where OSHA has determined from its 
analysis of technological feasibility it is needed to ensure employees 
are protected from exposures to respirable crystalline silica. These 
respirator requirements are divided by task duration (i.e., ``less than 
or equal to four-hours-per-shift'' and ``greater than four-hours-per-
shift'').
    Table 1 in the final standard differs from Table 1 in the proposed 
standard in a number of respects. As proposed, ``Table 1--Exposure 
Control Methods for Selected Construction Operations,'' listed 13 
construction operations that expose employees to respirable crystalline 
silica, as well as control strategies and respiratory protection that 
reduce those exposures. In developing Table 1 for the proposed 
standard, OSHA reviewed the industrial hygiene literature across the 
full range of construction activities and focused on tasks where 
silica-containing materials were most likely to be fractured or abraded 
and where control measures existed to offer protection against a 
variety of working conditions. OSHA also included additional 
specifications on proposed Table 1 to ensure that the strategies listed 
were properly implemented and remained effective.
    Table 1 was the subject of many comments in the rulemaking record. 
Commenters, such as BCTD, urged OSHA to reconsider its use of the 
proposed term ``operation'' to describe the activities listed on Table 
1 (Document ID 2371, Attachment 1, p. 23). Kellie Vazquez, on behalf of 
Holes Incorporated and CISC, suggested that it would be helpful to 
include more specifically-defined tasks, rather than broader operations 
(Document ID 2320, pp. 8-9). In the same vein, BCTD suggested that OSHA 
``revise [Table 1] to make clear that its focus is on particular silica 
dust-generating tasks, not more broadly-defined operations'' as ``there 
is an important distinction between specific tasks that may generate 
silica dust and the employer's overall operation, which may include 
different silica dust-generating tasks, requiring different controls'' 
(Document ID 2371, Attachment 1, p. 23). BCTD also recommended that, to 
avoid confusion, Table 1 should specify that each task is being 
performed on or with a material that contains silica (Document ID 2371, 
Attachment 1, p. 24). Responding to both suggestions, OSHA has changed 
the terminology used in Table 1 from ``Operation'' to ``Equipment/
Task'' to clarify that the controls apply to silica-generating 
activities done by employees and silica exposure generated by 
equipment, and has revised the title of Table 1 accordingly to 
``Specified Exposure Control Methods When Working with Materials 
Containing Crystalline Silica.''
    Other commenters requested that OSHA include additional activities 
on Table 1. The Sheet Metal Air Conditioning Contractors National 
Association (SMACNA) commented that using powder-actuated tools should 
be added (Document ID 2226, p. 2), and the Interlocking Concrete 
Pavement Institute (ICPI) suggested that OSHA include compacting 
pavers, sweeping sand into paver joints, and compacting the aggregate 
base (Document ID 2246, pp. 2, 11). NAHB noted that Table 1 failed to 
cover hand-mixing concrete (Document ID 2334, p. 4). OSHA did not 
receive data showing that employees engaged in many of these additional 
minor tasks (pulling concrete forms, mixing concrete for post holes, 
etc.) experience significant routine exposure to respirable crystalline 
silica above the action level that would require their employers to 
comply with provisions of this rule. Because OSHA does not currently 
have data indicating that additional controls for these tasks would be 
needed on a regular basis or would be effective, it has determined not 
to include them on Table 1.
    OSHA recognizes the possibility that employers may later discover 
that there are tasks that are not covered by Table 1 where they may 
have difficulty meeting the PEL. If such cases arise, OSHA can address 
them in several ways, including: considering technological or economic 
infeasibility defenses, and applying its variance process--either 
temporary or permanent, pursuant to which an

[[Page 16719]]

employer can apply to exclude an industry or process from enforcement 
of the standard based principally on a showing that it is providing 
equivalent protection for its workers.
    Several commenters requested that OSHA add tasks or activities and 
equipment to Table 1 that are associated with general industry 
operations such as asphalt plant operations, shale gas fracturing, and 
artificial stone and granite countertop work (Document ID 2212, p. 2; 
2116, Attachment 1, p. 28; 2244, p. 4). OSHA is not including these in 
the construction standard for the reasons discussed in the summary and 
explanation of Scope.
    NUCA requested that OSHA add underground construction, specifically 
excavation, onto Table 1, stating:

    The nature of excavation underground construction is 
continuously mobile. Exposure assessments take time to evaluate by a 
lab, and in that time, the jobsite conditions will change or crews 
will move to other sites. Test results simply could not be available 
in enough time to be relevant to a particular jobsite. This not only 
makes costly lab assessments irrelevant to particular sites, it also 
does nothing to protect the workers on those sites (Document ID 
2171, p. 2).

    OSHA's technological feasibility analysis for underground 
operations (Section 5.12 of Chapter IV of the FEA) indicates that 
employees performing activities not specific to tunneling, such as 
grinding, hole drilling, or chipping, receive similar exposures from 
their equipment as employees performing those same activities 
aboveground in enclosed environments (e.g., indoors). As a result, 
employers can comply with the dust control requirements of the standard 
by fully and properly implementing the dust controls specified on Table 
1 of the final standard for construction for those tasks. However, as 
explained in the technological feasibility analysis cited above, OSHA 
determined that it was not possible to develop a clear control 
specification that would prove effective for most situations where 
tunnel boring machines, road headers, and similar kinds of equipment 
are used. Effective dust control for operations that use these kinds of 
equipment consists of a combination of water sprays at the tunnel face 
and along the conveyors that remove material from the face, general 
dilution ventilation through the tunnel, local exhaust ventilation for 
excavating equipment and conveyor transfer points, and enclosed cabs 
for the operators. Dust control may also require enclosures for 
conveyors and belt cleaning mechanisms. Designing effective and 
efficient dust control systems must take into account specific factors 
of the tunnel project and equipment being used, and are analogous to 
dust control strategies used in underground mines, as described in 
NIOSH's Handbook for Dust Control in Mining (Document ID 0887). Given 
the degree of complexity and project-specific considerations that 
should be taken into account, OSHA determined that it was not possible 
to devise an effective specification applicable to all tunnel projects 
and thus has not added an entry for tunnel boring in underground 
construction to Table 1.
    Likewise, although abrasive blasting is a common source of silica 
exposure in construction, OSHA does not include an entry for abrasive 
blasting on Table 1 for reasons explained more fully below. As 
described in the Introduction to Chapter IV of the FEA, the tasks 
included on Table 1 of the final rule are those that have been widely 
recognized as high-exposure tasks in construction, and for which there 
has been considerable research performed on the effectiveness of dust 
control strategies. The record indicates that the tasks reflected in 
Table 1, with few exceptions such as underground construction and 
abrasive blasting, are the tasks that employers will most frequently 
need to address to ensure employee protection from crystalline silica 
hazards. For tasks not included on Table 1 that foreseeably generate 
silica exposures above the action level, construction employers will, 
in accordance with paragraph (d) of the standard for construction, need 
to conduct an exposure assessment and maintain exposures at or below 
the PEL through use of the traditional hierarchy of controls.
    Commenters also weighed in on OSHA's general approach to selecting 
the engineering controls and work practices for each task. LBA argued 
that there was a disconnect between the feasibility evidence and the 
controls and work practices included on Table 1 (Document ID 2269, p. 
17). NAHB urged OSHA to ensure that the protection methods included on 
Table 1 are based on verifiable studies that show effective solutions 
(Document ID 2296, p. 28). BCTD also opined that only ``control 
measures supported by good quality evidence should be listed on Table 
1'' (Document ID 2371, Attachment 1, p. 24).
    OSHA agrees that the engineering controls, work practices, and 
respiratory protection specified on Table 1 need to be consistent with 
the evidence presented in its technological feasibility analyses (see 
Chapter IV of the FEA). To that end, OSHA has based the specifications 
on Table 1 on extensive exposure data collected from a variety of 
sources including NIOSH reports, data submitted to the record, OSHA's 
compliance case files, and published literature.
    Requirements for water delivery systems and dust collection 
systems. OSHA is requiring the use of an integrated water delivery 
system supplied by the equipment manufacturer for several types of 
equipment listed on Table 1: Stationary masonry saws; handheld power 
saws (any blade diameter); walk-behind saws; drivable saws; rig-mounted 
core saws or drills; handheld grinders for uses other than mortar 
removal; and walk-behind milling machines and floor grinders. OSHA is 
requiring the use of systems that are developed in conjunction with the 
tool because they are more likely to control dust emissions effectively 
by applying water at the appropriate dust emission points based on tool 
configuration and not interfere with other tool components or safety 
devices.
    CISC commented that the requirement for an integrated water system 
limited options for employers and may reduce the use of the table, 
stating ``. . . if a construction employer finds a way to effectively 
deliver water through another mechanism, in the CISC's view that should 
be encouraged'' (Document ID 2319, p. 103; 2320, p. 16). OSHA expects 
that most employers will use integrated water systems, as provided by 
manufacturers, and will follow Table 1 but its intent is not to 
prohibit the use of other dust suppression methods during cutting. 
Employers may implement other controls or wet method configurations if 
they determine that the alternative control is more appropriate for 
their intended use. However, employers who choose to use controls not 
listed on Table 1 will be required to conduct exposure assessments and 
comply with the PEL in accordance with paragraph (d) of the standard 
for construction.
    CISC also questioned the appropriateness of requiring an integrated 
water delivery system when most integrated systems are intended to keep 
the blade cool and are not designed for dust suppression (Document ID 
2319, p. 103; 2320, p. 16). In written testimony, Rashod Johnson of the 
Mason Contractors Association of America stated that

the vast majority of masonry saws provide water on the blade itself. 
This is solely for the purpose of keeping the blade cool during 
cutting. A side effect, just happens to be dust suppression. Now, 
manufacturers of these saws are starting to explicitly state that 
the water used is for cooling the blade only and

[[Page 16720]]

should not be used to suppress dust (Document ID 2286, p. 2).

    However, product literature from five major saw manufacturers 
(Andreas Stihl, Husqvarna, Hilti, Makita USA, and Wacker Group) 
highlights the use of water application equipment to suppress dust in 
addition to blade cooling (Document ID 3998, Attachment 12a, pp. 9, 15-
16; 3998, Attachment 12e, p. 3; 3998, Attachment 12f; 3998, Attachment 
12g, p. 5; 3998, Attachment 12h, p. 8). For example, Stihl's manual for 
the model 410 and 420 cut-off machines (handheld masonry saws) 
specifically recommends a water flow rate for dust suppression 
(Document ID 3998, Attachment 12a, pp. 9, 15-16). Furthermore, Stihl is 
not the only cut-off saw manufacturer to state that water used with its 
product is intended to suppress dust emissions. Husqvarna's product 
literature for the K 3000 Wet describes the product as a power cutter 
for wet applications that is equipped with a dust extinguisher system 
(Document ID 3998, Attachment 12f, p. 1). Hilti also recognizes that 
water suppresses dust and recommends the use of wet cutting to reduce 
dust in its instruction manual for the Hilti DSH 700/DSH 900 model 
handheld masonry saws (Document ID 3998, Attachment 12e, p. 3).
    CISC asked that OSHA clarify whether there needs to be a separate 
integrated water delivery system in addition to the system provided by 
the manufacturer to keep the blade cool (Document ID 2319, p. 104). 
Beamer et al. (2005) conducted experiments to observe the differences 
in the various wet cutting methods available and found that the 
greatest improvement in dust reduction occurred with freely flowing 
water applied at a rate of 48 gallons per hour (0.8 gallons per 
minute), resulting in dust reduction of about 93 percent and confirming 
the benefits of water flowing over the stationary saw cutting blade 
compared with other misting systems (Document ID 1555, p. 509). That, 
in addition to the manufacturer information submitted to the record, 
indicates that the existing water systems for blade cooling are 
effective at respirable dust capture and will satisfy the requirements 
under paragraphs (c)(1)(i) through (c)(1)(xviii) of the standard for 
construction where integrated water systems are required. Therefore, 
OSHA has determined that, where water-based dust suppression can be 
used with tools and equipment, those that are equipped with an 
integrated water delivery system are effective and the best available 
technology for controlling respirable crystalline silica. A separate 
integrated water delivery system in addition to the system provided by 
the manufacturer to keep the blade cool is not required.
    OSHA is requiring the use of a commercially available dust 
collection system (i.e., local exhaust ventilation (LEV)) for several 
types of equipment listed on Table 1, including: handheld power saws 
for fiber cement board (with a blade diameter of 8 inches or less), 
handheld and stand-mounted drills (including impact and rotary hammer 
drills), jackhammers and handheld power chipping tools (as an 
alternative to a water delivery system), handheld grinders for mortar 
removal, and handheld grinders for uses other than mortar removal (as 
an alternative to a water delivery system). OSHA's intent is to ensure 
that employers use equipment that is appropriately designed for the 
tool being used and that will be effective in capturing dust generated 
from using the tool.
    CISC opposed OSHA's requirement for commercially available systems, 
stating ``[t]his specification eliminates specialty manufactured 
products that may be equally effective'' (Document ID 2320, p. 11). 
However, CISC did not provide examples or describe what is meant by 
``specialty manufactured products.'' It is not OSHA's intent to prevent 
employers from using products that are custom made by aftermarket 
manufacturers (i.e., made by someone other than the original tool 
manufacturer) which are intended to fit the make and model of the tool 
and designed to meet the particular needs and specifications of the 
employer purchasing the product. These systems are designed to work 
effectively with the equipment and not introduce new hazards such as 
obstructing or interfering with safety mechanisms. The ``commercially 
available'' limitation is meant only to eliminate do-it-yourself on-
site improvisations by the employer. An employer is free to improvise 
and use controls that are not commercially available. However, those 
systems would not meet the requirements of Table 1 and the employer 
will be required to conduct exposure assessments and comply with the 
PEL in accordance with paragraph (d) of the standard for construction.
    In Table 1 of the proposed rule, OSHA would have required dust 
collection systems be equipped with High-Efficiency Particulate Air 
(HEPA) filters, which are 99.97 percent efficient in capturing 
particles having an aerodynamic diameter of 0.3 [mu]m or larger. In the 
final standard, OSHA is not requiring the use of HEPA filters and 
instead is requiring the use of filters with a capture efficiency of 99 
percent or greater for respirable particulate. Although OSHA received 
comments and testimony in support of using HEPA filters to capture 
silica dust (Document ID 1953, pp. 3-4; 1973, pp. 2-3), extensive 
comments were submitted to the record expressing concern regarding this 
requirement.
    Occupational and Environmental Health Consulting Services, Inc. 
(OEHCS) noted the numerous deficiencies found with HEPA filtration from 
ineffective seals, deterioration of the filter, and inadequate testing 
prior to use, which often results in employee exposure to potentially-
hazardous particles and possible recontamination of the work 
environment (Document ID 1953, Attachment 1). The Precast/Prestressed 
Concrete Institute (PCI), NUCA, and LBA noted that HEPA filters do not 
work well in the construction environment because filters will clog up 
quickly and must be changed often (Document ID 2276, p. 10; 3729, p. 3; 
2269, p. 23). CISC noted that HEPA filters will typically not last an 
entire shift, stating that they clog up quickly and need to be 
monitored and changed frequently (Document ID 2320, p. 114). 
Consequently, CISC asserted, HEPA filters are not effective at 
filtering respirable dust or at reducing exposures to respirable silica 
(Document ID 2319, p. 95).
    OSHA reached the same conclusion in its technological feasibility 
finding for mortar and concrete grinding as well (see Section 5.11 of 
Chapter IV of the FEA). Finding that best practices may counsel toward 
the use of HEPA-rated filters in the case of grinding, and particularly 
mortar grinding, OSHA nonetheless determined that under field 
conditions HEPA filters may rapidly clog, leading to an increase in 
static pressure drop and loss of the airflow needed for LEV to 
effectively capture silica dust at the point of generation (Document ID 
0731, pp. 375, 384).
    OSHA is persuaded that it should not require that dust collection 
systems be equipped with HEPA filters because HEPA filters in some 
applications will result in loss of airflow and concomitant degradation 
of dust-capture efficiency. In examining manufacturers' specifications 
for many commercially-available dust collectors, OSHA finds that most 
offer, in addition to HEPA filters, other filters with a 99 percent 
efficiency or better in the respirable-particle-size range. Many 
examples of products equipped with filters that do not meet HEPA 
specifications but nevertheless meet the requirement for 99 percent 
efficiency in the respirable-particle-size range were submitted to the

[[Page 16721]]

record and include the EDCO Vortex 2000 (captures 99 percent of 0.5 
[micro]m or larger particles) (Document ID 4073, Attachment 4a, Row 
55), the iQ 360x stationary saw (99.5 percent, particle size 
unspecified) (Document ID 4073, Attachment 4a, Row 58), a Porter-Cable 
vacuum (99.85 percent, particle size unspecified) (Document ID 3998, 
Attachment 13p), the Bosch 3931A (99.93 percent of 3 [micro]m 
particles) (Document ID 3998, Attachment 10, p. 29), the CS Unitec 
(99.93 percent of 0.3 [micro]m particles) (Document ID 4073, Attachment 
4a, Row 99), and the Dustless 16-gallon collector (``almost HEPA,'' 
filters to 0.5 [micro]m particles) (Document ID 4073, Attachment 4a, 
Row 211). A filter efficiency of at least 99 percent allows for longer 
tool usage, compared to one with a HEPA filter, before significant 
drops in airflow of the dust collection system. Furthermore, as 
explained above, requiring that dust collectors be equipped with HEPA 
filters can cause rapid airflow drop, reducing dust capture efficiency 
at the shroud or hood and exposing employees to high respirable dust 
and silica concentrations. Therefore, OSHA has decided not to require 
HEPA filters on Table 1 for dust collection systems and instead 
requires that dust collectors have a filter with 99 percent or greater 
particle capture efficiency. Employers should consult with their 
suppliers to determine the dust collection equipment that will best 
suit their needs for a given application.
    OSHA also received many specific comments about particular changes 
to the notes and additional specifications, associated with the entries 
on Table 1, and on the specified engineering and work practice control 
methods identified for each entry, which are further discussed later in 
this section.
    Notes and additional specifications on Table 1. Several commenters 
responded to the appropriateness of including the notes and additional 
specifications in the individual entries on Table 1. OSHA included 
these in the proposed rule to ensure that the strategies listed were 
properly implemented and remained effective.
    Some commenters stated that the notes were too detailed, while 
others argued that the notes were not detailed enough (Document ID 
2319, p. 6; 2262, p. 29; 3581, Tr. 1631-1632; 3585, Tr. 2924-2925, 
3052-3053; 4223, pp. 95-97). Several commenters expressed concern that 
certain notes were unrealistic or too confusing for an employer to 
comply with. CISC stated that the inclusion of the notes left Table 1 
``unworkable'' for most employers in the construction industry 
(Document 2319, p. 6). Others questioned whether these additional 
specifications were a mandatory component of Table 1 or simply 
suggested guidelines to help determine the efficacy of the control 
(Document ID 2296, p. 28; 3441, pp. 4-5). On the other hand, some 
commenters asserted that the additional specifications were needed on 
Table 1 to ensure that controls are properly operated and effective 
(Document ID 3589, Tr. 4286-4287; 3581, Tr. 1631-1632; 4223, pp. 95-
97).
    To balance the need to clarify how the specifications apply to make 
Table 1 workable with the need to provide more specific information 
about the controls in order to ensure that they are effective, OSHA has 
removed most of the notes and additional specifications from the 
individual entries on Table 1 and has instead included revised 
specifications for the controls in paragraph (c)(2) of the standard for 
construction. This approach has the added benefit of making Table 1 
more readable because specifications that apply to multiple rows can 
now be addressed in a single subparagraph.
    Paragraph (c)(2)(i) of the standard for construction requires 
employers to provide a means of exhaust as needed to minimize the 
accumulation of visible airborne dust for tasks performed indoors or in 
enclosed areas. When tasks are performed indoors or in enclosed areas, 
the dispersal of dust can be impeded such that concentrations can build 
up without the aid of forced ventilation. Flanagan et al. (2006) 
concluded that the degree to which a work area is enclosed is an 
important determinant of employee exposure based on data demonstrating 
increased exposures to respirable crystalline silica for enclosed 
environments (those with two to four walls, as well as those having 
walls, a roof, and windows), as compared to outdoor environments 
(Document ID 0677, pp. 148-149). Increased exposures to respirable 
crystalline silica were also demonstrated for tasks listed on Table 1 
in enclosed areas, such as jackhammering inside a large pool area 
(Document ID 3958, Rows 1064, 1065, 1066) and handheld sawing in a 
large garage building open in front and closed on three sides (Document 
ID 3777, p. 65).
    Sufficient air circulation in enclosed or indoor environments is 
important to ensure the effectiveness of the control strategies 
included on Table 1 and to prevent the accumulation of airborne dust. 
The ``means of exhaust'' necessary to minimize the accumulation of 
visible airborne dust could include dilution ventilation through the 
use of portable fans that increase air movement and assist in the 
removal and dispersion of airborne dust, which would otherwise remain 
in the enclosure and contribute to elevated exposures. To be effective, 
the ventilation must be implemented so that movements of employees, or 
the opening of doors and windows, will not adversely affect the 
airflow.
    Paragraph (c)(2)(ii) of the standard for construction requires 
employers, for tasks performed using wet methods, to apply water at 
flow rates sufficient to minimize release of visible dust generated by 
the task. BCTD and LHSFNA encouraged OSHA to specify minimum flow rates 
for water where there are data or studies to support such a 
recommendation (Document ID 3581, Tr. 1632; 3589, Tr. 4286-4287). NIOSH 
recommended a flow rate of 0.5 L/min for handheld power saws based on 
experimental data and recommended that OSHA specify a minimum water 
flow rate of 300 mL/minute for jackhammers based on a field study of 
control equipment fabricated specifically for the study (Document ID 
2177, Attachment B, pp. 19, 33; 0867, p. 6). Water has been proven an 
efficient engineering control method to reduce exposures to airborne 
crystalline silica-containing dust. Adequate dust capture is dependent 
on a variety of factors such as dust particle size, velocity, spray 
nozzle size and location, use of surfactants or other binders, and 
environmental factors (water hardness, humidity, weather, etc.) that 
must be considered when implementing wet methods. Water flow rates 
suggested by various studies, while perhaps instructive, may not be 
applicable to all of the different types of equipment that could be 
used or the conditions that may be encountered by employers following 
Table 1. Because the appropriate water flow rates for controlling 
silica dust emissions can vary, OSHA is not establishing a required 
flow rate for wet suppression systems or specifying a flow rate for 
individual Table 1 entries.
    Paragraphs (c)(2)(iii)(A)-(F) of the standard for construction 
require employers implementing measures that include an enclosed cab or 
booth to ensure that the enclosed cab or booth is maintained as free as 
practicable from settled dust, has door seals and closing mechanisms 
that work properly, has gaskets and seals that are in good condition 
and work properly, is under positive pressure maintained through 
continuous delivery of fresh air, has intake air that is filtered 
through a pre-filter that is 95 percent efficient in the 0.3-10.0 
[micro]m range (e.g., MERV-16 or

[[Page 16722]]

better), and has heating and cooling capabilities.
    Dust can be unintentionally carried into enclosed cabs or booths 
through a number of routes, including on employees' boots, during the 
opening of doors when accessing or exiting the cab, through leaks in 
the system, or when employees roll down windows. IUOE, recommending 
that OSHA add specificity to the cab requirements (e.g., heating and 
air conditioning, housekeeping), argued that without greater 
specificity ``there is a grave danger that intended safeguards become 
counterproductive as dust is re-circulated within the enclosures'' 
(Document ID 2262, pp. 29-33).
    Direct-reading instruments show that fine particle (0.3 micron 
([mu]m) in size) concentrations inside operator cabs can be reduced by 
an average of 93 percent when cabs are clean, sealed, and have a 
functionally adequate filtration and pressurization system (Document ID 
1563, p. 1). Cecala et al. (2005) studied modifications designed to 
lower respirable dust levels in an enclosed cab on a 20-year-old 
surface drill at a silica sand operation. The study found that 
effective filtration and cab integrity (e.g., new gaskets, sealed 
cracks to maintain a positive-pressure environment) are the two key 
components necessary for dust control in an enclosed cab (Document ID 
1563, p. 1).
    OSHA determined that the requirements specified in paragraphs 
(c)(2)(iii)(A)-(F) of the standard for construction reduce the 
likelihood of respirable crystalline silica exposure in enclosed cabs 
or booths when employees are present by lowering the potential for dust 
to be re-suspended inside the enclosure, promoting the ability of the 
enclosed cab or booth to keep dust from entering through cracks or 
openings (e.g., seals, gaskets, and closing mechanisms are present, in 
good condition, and work properly), ensuring that the working 
conditions in the cab are comfortable so that employees are less likely 
to open the window of the cab, and ensuring that the fresh air provided 
to the employee does not contain silica particles.
    IUOE also suggested that OSHA require employers to provide boot 
brushes or mudflingers to minimize the dust brought into the cab, to 
equip cabs with dust-resistant materials, and to affix warning labels 
to the interior of the cab (Document ID 2262, p. 30; 4025, p. 17). The 
Agency has not included these additional requirements since it expects 
that the specifications in paragraphs (c)(2)(iii)(A)-(F) of the 
standard for construction combined with frequent inspections by the 
competent person will be sufficient to protect employees against the 
potential respirable crystalline silica exposures within the enclosure.
    OSHA has not included more specific requirements in paragraphs 
(c)(2)(i)-(c)(2)(iii) of the standard for construction (e.g., 
establishing a minimum face velocity, volumetric flow rate for air 
movement, or a required number of air changes; flow rate for wet 
suppression systems; or a frequency for the cleaning of cabs or 
booths). However, as discussed in the summary and explanation of 
Written Exposure Control Plan, paragraph (g)(1)(ii) of the standard for 
construction requires the employer to establish and implement a written 
exposure control plan that describes the engineering controls and work 
practices used to limit employee exposure to respirable crystalline 
silica. This description should include details such as the appropriate 
means of exhaust needed to minimize the accumulation of visible 
airborne dust for a particular task, the appropriate flow rate and 
droplet size needed for wet suppression systems to minimize release of 
visible dust, and the procedures for maintaining and cleaning an 
enclosed cab or booth. Paragraph (g)(4) of the standard for 
construction also requires a competent person to make frequent and 
regular inspections of the jobsite, materials, and equipment (including 
engineering controls) to implement the written exposure control plan.
    OSHA did not include specifications on visible dust and wet slurry, 
included as notes in individual entries on proposed Table 1, in the 
standard. The Agency has determined that these issues are best 
addressed by other provisions of the standard, rather than as a note or 
additional specification included in each relevant Table 1 entry. 
Further discussion about these specifications is also included below.
    Many commenters expressed concern with the note, contained in 
proposed Table 1 for all but two entries, requiring employers to 
operate equipment such that no visible dust is emitted from the 
process. Industry commenters, including the Power Tool Institute (PTI), 
Western Construction Group, SMACNA, the Independent Electrical 
Contractors, the Distribution Contractors Association, CISC, the 
Utility and Transportation Contractors Association of New Jersey, 
Atlantic Concrete Cutting, ABC, LBA, Holes Incorporated, and N.S. Giles 
Foundations objected to this note, stating that it was an unrealistic 
requirement which made Table 1 unworkable (e.g., Document ID 1973, pp. 
2-9; 2183, p. 3; 2226, p. 2; 2250, p. 2; 2309, p. 4; 2319, pp. 97-98; 
4217, p. 6; 2356, p. 2; 2367, p. 2; 2289, p. 7; 2269, p. 21; 3441, p. 
5; 3598, pp. 1-2).
    Some industry commenters asserted that it is impossible to perform 
tasks, such as sawing, grinding, and drilling, without generating any 
visible dust (Document ID 2357, pp. 27-28; 3441, p. 6; 4073, Attachment 
9e, p. 1). Holes Incorporated noted that when grinding or using other 
hand-held pieces of equipment, the work cannot be performed with the 
tool flush against the impacted surface, and at times, there will be a 
gap and visible dust will be emitted even when local exhaust 
ventilation or wet methods are utilized (Document ID 3441, p. 6).
    Other commenters expressed concern that there is no true dustless 
system, clarifying that even those tools marketed as ``dustless'' 
produce some level of airborne dust (Document ID 2345, p. 4; 3585, Tr. 
2960; 4216, pp. 2-3). Francisco Trujillo, safety director for Miller 
and Long, stated that:

    Every ``dustless'' system I have ever witnessed has produced 
some level of airborne dust. This fact alone should show that Table 
1 sets criteria that are impossible to achieve . . . (Document ID 
2345, p. 4).

    On the other hand, commenters, including NAPA and BAC, noted that 
in their experience there is no visible dust generated when certain 
equipment, such as asphalt machines for milling or stationary masonry 
saws, is used with available dust controls (Document ID 3583, Tr. 2216; 
3585, Tr. 3072). They did not, however, provide any indication that the 
same results could be achieved with all of the other equipment listed 
on Table 1.
    Several commenters provided a different rationale for their 
objections to this note. AIHA opined that the requirement to operate 
equipment such that no visible dust is emitted from the process is a 
subjective determination and recommended it be removed from Table 1 
entries (Document ID 3578, Tr. 1029-1030; 2169, p. 5). The Masonry and 
Concrete Saw Manufacturers Institute (SMI) noted that ``[a]dding 
requirements for . . . avoiding visible dust have not been researched 
specific to respirable silica dust and may have no beneficial impact'' 
(Document ID 2316, p. 2). NAHB and Holes Incorporated expressed concern 
that the requirement was a general dust rule, rather than regulating 
crystalline silica since Table 1 doesn't specify whether ``no visible 
dust'' refers to visible silica dust or just dust in general (Document 
ID 2296, p. 29; 3580, Tr. 1355-1356).

[[Page 16723]]

    Not all industry commenters objected to the note on visible dust 
contained in the proposed Table 1. ICPI supported a version of Table 1 
that included the no-visible-dust requirement for nearly all of the 
operations listed (Document ID 2352, pp. 4-8).
    Commenters from both industry and labor suggested revisions to 
clarify the note and make it workable. LHSFNA believed the note was 
needed to ensure the effective use of controls and was not too vague, 
but acknowledged that the language could be clarified to say something 
like ``visible dust should be minimized'' (Document ID 4207, p. 2). 
BCTD also provided significantly revised language for the no-visible-
dust requirement. For those operations that involve cutting and 
grinding on silica-containing substrate, BCTD suggested that, for wet 
systems, Table 1 of the standard should require that water flow be 
``sufficient to control the dust generated so that no visible dust . . 
. is emitted from the process once the blade has entered the substrate 
being cut'' and that the relevant note on Table 1 be revised to read:

    A small amount of visible dust may be present when the blade or 
tool initially enters the substrate and when it is being removed at 
the end of a task. However, if visible dust is present after the 
blade or tool has entered the work surface/substrate, this is a sign 
that the control is not working properly. The operation should be 
stopped and the equipment and/or workers' cutting technique checked 
and fixed (Document ID 4223, Appendix 1, p. 14).

    PTI's suggested revisions to Table 1 include a note for many of the 
entries specifying that ``during operation, if excessive visible dust 
is emitted from the process, immediately stop work and verify that the 
dust control system is functioning properly'' (Document ID 1973, pp. 2-
9).
    While opinions varied widely on the utility of a no-visible-dust 
requirement, no commenters suggested that excessive visible dust 
generated from tasks abrading silica-containing materials (sawing, 
grinding, etc.) does not present a risk of significant employee 
exposure to silica. As noted above, BCTD confirmed that the presence of 
visible dust after the blade or tool has entered the work surface/
substrate is a sign that the control method is not working properly 
(Document ID 4223, Appendix 1, p. 14). PTI recommended that, when 
excessive visible dust was present, work stop immediately until the 
employer could verify the proper functioning of the control (Document 
ID 1973, pp. 2-9).
    OSHA agrees that excessive visible dust is an indication that a 
control's effectiveness may be compromised, but, after reviewing the 
entire record on this point, has decided not to include a no-visible-
dust requirement for the Table 1 entries. Instead, it has concluded 
that the purpose of such a requirement is best achieved by bolstering 
other requirements in the rule, as it applies to construction. First, 
OSHA considers the written exposure control plan to be centrally 
important and expects employers to address signs that controls may not 
be working effectively (e.g., dust is visible) as part of their written 
exposure control plans required under paragraph (g) of the standard for 
construction (see summary and explanation of Written Exposure Control 
Plan for further discussion). Second, during the designated competent 
person's frequent and regular inspections of job sites, materials, and 
equipment to implement the written exposure control plan, as required 
under paragraph (g)(4) of the standard for construction, OSHA expects 
that person to make routine observations of dust generated from tasks 
being conducted. Where increases in visible dust occur, the competent 
person's assigned role is to take prompt corrective action (e.g., make 
corrections or adjustments as needed).
    OSHA finds that the difference between the small amount of dust 
generated when control measures are operated effectively and the large 
amount of dust generated during tasks when control measures are not 
used or not operated effectively can readily be observed. Several 
videos presented in the record support this conclusion (e.g., Document 
ID 4073, Attachment 4b). These videos demonstrate that when a task is 
uncontrolled or inadequately controlled, a large dust plume can be 
seen. When controls such as water or vacuum-based ventilation are used, 
little dust is observable. These significant differences in the 
observable dust generated during controlled and inadequately-controlled 
tasks provide an opportunity for employers to readily detect poorly-
performing equipment and address these problems quickly. The principle 
concern, however, is with a lot of visible dust, rather than any 
visible dust, which is a concern for which the appropriate corrective 
action is difficult to quantify or state in objective terms. Instead, 
the presence of significant visible dust lends itself to a more 
process-oriented control approach, as exemplified by the written 
exposure control plan and competent person requirements. OSHA thus 
concludes that the issue of visible dust is best addressed by the 
requirement to fully and properly implement the controls specified on 
Table 1, and the written exposure control plan and competent person 
requirements, rather than as a note or additional specification 
included in each Table 1 entry.
    Commenters also objected to the specification to prevent wet slurry 
from accumulating and drying when implementing wet methods, as proposed 
for several Table 1 entries. Both Holes Incorporated and NAHB objected 
to the ambiguity of the requirement and presented concerns about how 
employers on a construction site would comply with such a requirement 
(Document ID 3441, p. 9; 2296, p. 28).
    Other commenters expressed concern regarding the disposal of silica 
slurry (Document ID 2246, pp. 9-10; 3585, Tr. 2886; 2319, p. 94). ICPI 
noted that employers have to expend extra effort to locate a place to 
dispose of dust-filled slurry, which is not possible in some conditions 
or locations (Document ID 2246, pp. 9-10). CISC described how slurry 
created using wet-cutting methods outside can flow into storm drains, 
potentially violating environmental regulations (Document ID 2319, p. 
94). The Mason Contractors Association of America explained that in 
California, silica slurry produced from wet cutting is classified as a 
hazardous material, requiring contractors working in the state to 
follow hazmat procedures for its disposal (Document ID 3585, Tr. 2886).
    However, NIOSH argued that since the vast majority of masonry saws 
provide water on the blade itself to cool and lubricate the blade and 
suppress dust, employers already have to deal with slurry when cutting 
masonry and concrete (Document ID 4233, Attachment 1, p. 6). OSHA 
agrees that the standard does not pose any new requirements regarding 
the disposal of slurry on employers who already use wet methods for 
sawing masonry products.
    OSHA concludes that any measures necessary to manage slurry in 
order limit employee exposure to respirable crystalline silica (i.e., 
exposure that results from slurry drying and dust particles becoming 
airborne) are best addressed through the employer's written exposure 
control plan and competent person requirements, rather than as a note 
or additional specification included in each Table 1 entry. These 
requirements are discussed above and in the summary and explanation of 
Written Exposure Control Plan.
    In several Table 1 entries, OSHA has included a requirement to 
operate and maintain tools in accordance with

[[Page 16724]]

manufacturer's instructions to minimize dust emissions. This 
requirement is intended to ensure that the controls are implemented 
effectively to reduce exposures to respirable crystalline silica. 
Manufacturer's instructions that influence the effectiveness of the 
tool and controls with regard to minimizing dust emissions may include, 
but are not limited to, additional specifications for water flow rates, 
air flow rates, vacuum equipment, rotation of the blade, maintaining 
and changing blades, and frequencies for changing water.
    Respiratory protection specified on Table 1. Industry associations, 
including the American Subcontractors Association (ASA), the Institute 
of Makers of Explosives (IME), the General Contractors Association of 
New York (GCANY), and CISC, commented on the appropriateness of the 
respirators that OSHA proposed for Table 1 (e.g., Document ID 2213, p. 
2; 2187, p. 3; 2314, p. 2; 2319, p. 102). For example, ASA stated:

    OSHA's proposed Table 1 for construction would seem to suggest 
that the Agency believes a construction employer can achieve the PEL 
with engineering and work practice controls. Yet the Agency then 
requires respiratory protection for 60 percent of the operations 
listed in Table 1. This failure is even more perplexing since OSHA 
failed to identify, obtain and/or cite sufficient data for its 
conclusions with respect to the 13 operations addressed in Table 1 
(Document ID 2187, p. 3).

GCANY explained in their comments that ``[c]urrent respiratory 
protective equipment is cumbersome to wear and to work in and would 
expose the worker to other hazards on a job site'' (Document ID 2314, 
p. 2). CISC urged OSHA to ``eliminate the heavy use of respiratory 
protection,'' arguing that:

    OSHA's reliance on respiratory protection is analytically 
inconsistent with its position that it is technologically feasible 
to reach the proposed PEL in most construction operations most of 
the time, and particularly when the control measures specified in 
Table 1 are used. Requiring such heavy use of respirators . . . will 
serve as a significant barrier to effective use of [Table 1] 
(Document ID 2319, p. 102).

    Respirator requirements on Table 1 of the final rule are based on a 
review of all the evidence pertaining to exposure profiles and 
available controls in the rulemaking record, including an evaluation of 
the updated exposure profiles and evidence on available controls 
submitted to the rulemaking record, as described in Chapter IV of the 
FEA. A primary purpose of such evaluation was for OSHA to better 
identify those situations where exposures above the PEL are likely to 
persist despite full and proper implementation of the specified 
engineering and work practice controls and supplemental respiratory 
protection will therefore be necessary to ensure employees are 
protected from silica-related health risks. As documented in its 
analyses of technological feasibility for each Table 1 task, OSHA finds 
that most of the time employees are performing tasks on Table 1, 
respiratory protection will not be required. For most of the tasks or 
equipment on Table 1, OSHA expects that work will be performed for four 
hours or less and/or outdoors (see Chapter IV of the FEA). For certain 
tasks listed on Table 1, OSHA was able to distinguish indoor 
environments, where exposures are typically above 50 [micro]g/m\3\ even 
with the use of engineering controls and work practices, from outdoor 
environments, where engineering controls can typically maintain 
exposures below 50 [micro]g/m\3\, in order to eliminate requirements 
for respiratory protection where tasks are performed outdoors (e.g., 
using handheld grinders for uses other than mortar removal 
(c)(1)(xii)). Elsewhere, OSHA was able to further refine the equipment 
or tasks listed on Table 1 (e.g., handheld power saws (c)(1)(ii)-(iii); 
walk-behind and drivable masonry saws (c)(iv)-(v); milling machines 
(c)(1)(xiii)-(xv)) in order to eliminate previously proposed 
requirements for respiratory protection. In other cases, OSHA found 
engineering controls and work practices specified on Table 1 sufficient 
to maintain employee exposures at or below 50 [micro]g/m\3\ when fully 
and properly implemented (e.g., (c)(1)(i), (c)(1)(ix), (c)(1)(xiv)), 
and thus determined that a respiratory protection requirement was not 
necessary. Specific changes to the respiratory protection requirements 
for each task listed on Table 1 are discussed in more detail below.
    Consequently, required respiratory protection under Table 1 is 
limited to situations in which OSHA has determined that exposures over 
50 [micro]g/m\3\ will often occur. For example, OSHA is not requiring 
the use of respiratory protection when handheld power saws (any blade 
diameter) are used outdoors, for less than four hours, with water-based 
dust suppression systems because OSHA's exposure profile indicates that 
exposures will be below 50 [micro]g/m\3\ TWA most of the time that saws 
are used, given typical work patterns (e.g., outdoors for less than 
four hours per shift) (see Section 5.6 of Chapter IV of the FEA). Data 
submitted to the record by the Concrete Sawing and Drilling Association 
(CSDA) (Document ID 3497) also show that wet sawing produces exposures 
below 50 [micro]g/m\3\ TWA with typical use patterns during the work 
shift. In contrast, indoor use of handheld wet power saws generates 
frequent exposures in excess of 50 [micro]g/m\3\ TWA with typical use 
patterns during the work shift; from OSHA's exposure profile, half of 
the exposure samples associated with using handheld power saws indoors 
exceed 50 [micro]g/m\3\ TWA, and two indoor samples included in the 
data submitted by CSDA were above a TWA of 50 [micro]g/m\3\ (Document 
ID 3497, p. 5). As a result, Table 1 requires supplemental respirator 
use when handheld power saws are used indoors or in an enclosed area 
with water-based dust suppression systems.
    OSHA has also used the terms ``indoors or in an enclosed area'' 
rather than ``indoors or within a partially sheltered area'' in order 
to clarify that any requirement to use respiratory protection when the 
task is performed under these conditions is limited to those areas 
where the dispersal of dust can be impeded such that concentrations can 
build up without the aid of forced ventilation. For example, a work 
area with only a roof that does not impede the dispersal of dust would 
not be considered ``enclosed,'' while it may have been considered by 
some to be a ``partially sheltered area.''
    As a result of these modifications, OSHA expects that many fewer 
employees will need to use respiratory protection than was the case for 
the proposed rule, and respiratory protection will not be necessary for 
the most commonly encountered work situations and environments 
specified on Table 1.
    ISEA suggested that OSHA make the respirator requirements on Table 
1 more user-friendly and performance-oriented by listing only an APF 
and recommending that users consult the APF table found in the 
respiratory protection standard, rather than listing generic respirator 
types (Document ID 2212, p. 2). In response to this comment, OSHA has 
maintained certain requirements for respiratory protection, but has 
eliminated specific requirements for the type of respirator that must 
be used (e.g., half-mask respirator, powered air-purifying respirator 
(PAPR) with loose-fitting helmet or negative pressure full facepiece). 
Instead, OSHA includes on Table 1 only the minimum Assigned Protection 
Factor (APF) required. This change from the proposal provides the 
employer with the option of determining which respirator offers the 
best protection for its employees in the multitude of construction 
environments

[[Page 16725]]

that may be encountered. However, this is only the minimum protection 
factor required for the respirator, and employers have the flexibility 
to provide a more protective respirator to those employees who request 
one or require a more protective respirator based on the employer's 
evaluation of the worksite. As discussed in the summary and explanation 
of Respiratory Protection, paragraph (d)(3)(i)(A) of the respiratory 
protection standard (29 CFR 1910.134), which includes a table that can 
be used to determine the type or class of respirator that is expected 
to provide employees with a particular APF, can help employers 
determine the type of respirator that would meet the required minimum 
APF specified by Table 1. In order to reflect this change to the 
respirator requirements, the Agency has modified the heading on Table 1 
to ``Required Respiratory Protection and Minimum Assigned Protection 
Factor (APF).''
    The respirator requirements on Table 1 are divided by task 
duration: ``less than or equal to four hours/shift'' and ``greater than 
four hours/shift.'' AIHA recommended that OSHA clarify what time is 
included when determining less than or greater than four hours 
(Document ID 2169, p. 6). OSHA has determined that time starts when the 
operator begins using the tool, and continues to be counted until he or 
she completes the task. This time includes intermittent breaks in tool 
usage and clean-up. For example, an employee cuts and places bricks, 
one at a time, for three hours consecutively. The employee then spends 
30 minutes cleaning up the saw and empting slurry or dust collectors. 
All three hours spent cutting and laying bricks along with the 30 
minutes for clean-up count. Tasks that are performed multiple times per 
day, during distinct time periods, should be counted as separate tasks, 
and times should be combined. For example, an employee cuts multiple 
bricks for 15 minutes, lays bricks for two hours and returns to cut 
more bricks for another 30 minutes. The two hours spent laying bricks 
do not count towards the total time for compliance with Table 1.
    The duration of a task that generates respirable crystalline silica 
influences the extent of employee exposure and, in some cases, 
requirements for use of respirators. Some commenters suggested that 
OSHA modify the time breakdown for activities and respirator usage, 
such as BCTD's suggestion to divide tasks on Table 1 into two hours, 
four hours, and eight hours. Other commenters such as CISC, Holes 
Incorporated, and the Mason Contractors Association of America, 
suggested that OSHA exclude short duration tasks (e.g., 90 minutes or 
less) from Table 1, and NUCA suggested that the four hour cutoff is 
arbitrary and had no data to support it (Document ID 4073, Attachment 
14f, p. 2; 2319, pp. 100-102; 3580, Tr. 1453; 3585, Tr. 2882; 3729, p. 
3).
    After reviewing these comments, OSHA has decided to maintain this 
division in the standard. OSHA selected four hours as an appropriate 
division point for respirator usage because it finds that employers and 
employees can anticipate whether a task will take less than half of a 
shift or more than half of a shift (as opposed to smaller time 
intervals), and so can plan accordingly on the need for respirator use 
on a given job. In addition, OSHA selected only a single durational 
division for respirator tasks in all of the relevant Table 1 tasks to 
avoid the confusion that could result from triggering mandatory 
respirator use at different times for different tasks. OSHA also 
determined that excluding short duration tasks from Table 1, although 
included in the ASTM E 2625-09 consensus standard, was inappropriate, 
given that employees engaged in a task listed on Table 1 are best 
protected using the available engineering controls, work practices, and 
respiratory protection specified for the task and are only exempt from 
complying with the standard where employee exposure will remain below 
25 [micro]g/m\3\ as a time-weighted average under any foreseeable 
conditions (see summary and explanation of Scope for further discussion 
of this exclusion).
    Table 1 of the proposed rule used the phrase ``4 hours per day'' to 
indicate when respirators were required, but Table 1 of the final 
standard uses ``4 hours per shift.'' OSHA's exposure data is largely 
drawn from samples of employee exposure averaged over an 8-hour period, 
which is a typical time for a shift. The proposed rule referred to a 
time period of four hours ``per day'' for the purpose of limiting 
employee's exposure during the normal 8-hour shift that most employees 
work during a single day. OSHA recognizes, however, that some common 
tasks such as jackhammering during nighttime highway construction may 
occur during an 8-hour period that spans two calendar days (e.g., 8 
p.m. until 4 a.m.). OSHA did not intend to allow employees to be 
exposed to respirable crystalline silica without respiratory protection 
for longer than four hours in that scenario, so OSHA has specified four 
hours ``per shift'' in the final rule.
    OSHA also recognizes that the form and length of a shift may vary 
such that an employee may have a break between work periods (e.g., four 
hours on, two hours off, four hours on), work shifts may be longer than 
eight hours, or employees may work double shifts within a single day. 
The work periods in each of those examples constitutes a ``shift'' for 
purposes of determining the maximum amount of time that an employee may 
spend on one of the applicable Table 1 tasks without respiratory 
protection. OSHA's exposure data is not sufficient to support the 
conclusion that a longer duration of exposure without respiratory 
protection would be safe just because that exposure is spread out over 
a period that is longer than the normal 8-hour shift. Thus, an employee 
who works a 12-hour shift from 8 p.m. to 10 a.m. with a 2-hour rest 
break in the middle would have to wear a respirator if engaged in an 
applicable Table 1 task such as jackhammering outdoors if the employee 
will be jackhammering from 8 p.m. to 11 p.m., taking a break from 11 
p.m. until 2 a.m., and then jackhammering again from 2 a.m. until 4 
a.m. for a total of five hours of jackhammering. However, assuming no 
other silica exposure, the employee would not require respiratory 
protection if the jackhammering is limited to 8 p.m. until 11 p.m. and 
2 a.m. until 3 a.m. for a total of four hours, even if the employee 
repeats the same shift and jackhammering times every day of the week. 
Accordingly, the change from ``per day'' to ``per shift'' clarifies 
OSHA's original intention regarding when respirator use is required for 
Table 1 tasks.
    The requirement to provide respirators for Table 1 tasks is based 
on the anticipated duration of the task. Some commenters, such as EEI, 
expressed confusion about how this requirement would apply to non-
continuous work (e.g., Document ID 2357, p. 27). EEI opined that:

    The nature of non-continuous work can also make it hard to 
anticipate when a certain task may exceed four hours per day. 
Suppose, for example, a job task using a stationary masonry saw is 
not anticipated to last beyond four hours, so all controls listed in 
Table 1 are followed, and the employee does not wear a respirator. 
Then, due to unforeseen complications, the job lasts beyond four 
hours. Simply following the regulations as proposed, it is unclear 
whether the employee would be allowed to put on a half-mask after 
four hours, or if OSHA will not allow the employer to use the Table 
1 option because the employee was not in a half-mask for the first 
four hours (Document ID 2357, p. 27).

In contrast, other commenters suggested that, despite the variable 
nature of the work, employers and employees generally know how long it 
will take to complete a particular task (e.g.,

[[Page 16726]]

Document ID 3581, Tr. 1684, 1686). OSHA recognizes, based on the 
comments above and the nature of construction work in general, that 
application of this requirement warrants some flexibility. For several 
Table 1 tasks, respiratory protection with the appropriate APF is 
required if the duration of a task is anticipated to exceed four hours, 
but is not required if the duration of a task is less than or equal to 
four hours (e.g., (c)(1)(ii), (c)(1)(x), (c)(1)(xii)). For these tasks, 
the Agency does not expect employers to know exactly how long it will 
take to perform a task. Rather, OSHA expects employers to make a good-
faith judgment of the task's anticipated duration over the work shift 
based on previous experience and all other available information. If 
the employer anticipates that an employee will be engaged in a task for 
more than four hours, the employer must provide respirators (if 
required by Table 1) to the employee at the beginning of the shift. For 
example, in the case of an employee grinding concrete walls indoors, 
the employer should know, in advance, the area of surface that is to be 
worked on in the course of a shift. If, based on the employer's 
experience, the time needed to grind that area is typically less than 
four hours, the employer would not be required to provide respirators 
to the employee. If, however, using the same example, the employer 
experiences unforeseen difficulties that extend the task duration 
beyond four hours, the employer would be required under Table 1 to 
provide the listed respiratory protection as soon as it becomes evident 
that the duration of the grinding task may exceed the 4-hour limit, 
measured from the beginning of the task rather than the point when the 
need for extra time becomes evident.
    Commenters, including BCTD, Fann Contracting, and IUOE, expressed 
confusion about whether an employee must wear a respirator for the 
entire duration of a task when that task is expected to last more than 
four hours, or rather wear the respirator for only the portion of the 
task that exceeds four hours (e.g., Document ID 3581, Tr. 1681; 2116, 
Attachment 1, p. 28; 2262, p. 27). OSHA hereby clarifies that the 
intent is to require respirator use throughout the duration of the 
task.
    The objective of the silica standard is to limit an employee's 
average exposure over a work shift. In each of OSHA's health standards, 
this is accomplished by establishing a PEL expressed as an 8-hour TWA. 
Because a PEL is a time-weighted average, the Agency has traditionally 
required employees to use respirators throughout a shift when employees 
work on a task or in an area where exposure to a hazardous substance 
contributes significantly to an employee's exposure in excess of the 
PEL at any point during that shift. This same reasoning applies to 
wearing a respirator from the beginning of a shift where respirators 
are required on Table 1. Thus, OSHA is continuing the same approach to 
respirator use for tasks listed on Table 1 of the standard for 
construction as it has for other OSHA health standards. Under Table 1 
of the final standard for construction, when a respirator is required 
only when a task is performed for more than four hours per shift and 
when the employer estimates that the duration of the task will exceed 
four hours, the employer must provide and ensure that a respirator is 
used the entire time that task is performed over the shift, not just 
during the time beyond the first four hours that the task is performed. 
For example, if an employer anticipates that an employee will operate a 
jackhammer outdoors for more than four hours, the employer must provide 
respiratory protection with an APF of 10 and require that it be used 
for the entire duration of the task. For tasks that are typically 
intermittent, employers are required to estimate at the outset the 
total time during the shift that the task itself will be performed and 
provide respirators required by Table 1 based on that estimate. If an 
employer knows from experience that an employee will perform a single 
task listed on Table 1 for four hours or less during a single shift, 
then the employer must ensure that the employee uses whichever 
respirator is specified in the ``<= 4 hr/shift'' column on Table 1 (or 
need not provide a respirator if no respirator is required on Table 1 
for that duration). As another example, if a contractor needs to cut 
four concrete walls using a handheld power saw (outdoors), and cutting 
each wall typically takes 45 minutes to complete, for a total time of 3 
hours, the employer would not be required by Table 1 to provide a 
respirator. But if cutting each wall typically takes in excess of 60 
minutes, the employer should expect that the total duration of the task 
will exceed four hours and provide respirators as required under Table 
1. The employer is required to provide respirators as soon as it 
becomes evident that the duration of the task will exceed four hours. 
Thus, in most situations an employee will be protected by a respirator 
for all or the majority of a task that exceeds four hours because the 
rate of progress on the task will become apparent to the employer early 
on. An employee cannot be allowed to work more than four hours without 
a respirator when one is required under Table 1 because the employer 
will have certainty at that point that the task is exceeding four 
hours.
    The above examples assume that employees are engaged in only one 
task covered by Table 1 each shift. Paragraph (c)(3) of the standard 
for construction requires that, where employees perform more than one 
task on Table 1 during the course of a shift for a combined total of 
more than four hours, employers must provide, for the entire duration 
of each task performed, respiratory protection that is consistent with 
that specified in the ``> 4 hr/shift'' column of Table 1, even if the 
individual duration of each task is less than four hours. If no 
respirator is specified for a task in the ``> 4 hr/shift'' column of 
Table 1, then respirator use would not be required for that part of the 
employee's shift. For example, if an employer plans to have his 
employee use a handheld grinder outdoors on a concrete wall for three 
hours and then use a chipping hammer for two additional hours, the 
employer would not be required to ensure that his employee uses a 
respirator for the three hours the employee is using the grinder, since 
respiratory protection is not specified on Table 1 for the use of a 
grinder outdoors for more than four hours per shift; however, the 
employer would be required to ensure that his employee uses a 
respirator with an APF of 10 for the two hours the employee is using 
the chipping hammer. This is so even though use of the chipping hammer, 
if performed with no grinding beforehand, would not have required a 
respirator for the duration that the tool was used. If the employee 
will be engaged in two activities that both have ``None'' specified for 
respiratory protection in both the ``<= 4hr/shift'' and the ``> 4 hr/
shift'' columns, such as driving a half-lane milling machine and then 
operating a walk-behind milling machine equipped with an integrated 
water delivery system, then respirator use would not be required for 
any part of an employee's shift even if the employer knows that the 
cumulative total of that work will exceed four hours.
    When an employee performs multiple tasks that do not exceed a 
combined total of more than four hours, employers must provide the 
respiratory protection specified in the ``<= 4 hr/shift'' column of 
Table 1 for each task. For example, if an employer plans to have his 
employee use a handheld grinder for mortar removal for one hour and a 
stationary masonry saw for an

[[Page 16727]]

additional two hours, the employer is required to ensure that his 
employee uses a respirator with an APF of 10 for the one hour the 
employee is using the grinder. The employer would not be required to 
ensure that his employee uses a respirator for the two hours the 
employee is using the stationary masonry saw, since respiratory 
protection is not specified on Table 1 for the use of a stationary 
masonry saw.
    Thus, whatever permutations may arise, the employer must estimate 
the duration of the task(s) to determine whether Table 1 will trigger 
the requirement for respiratory protection. If unforeseen conditions 
arise that cause the estimated duration to be revised for any of the 
tasks, the employer is required to provide the required respiratory 
protection as soon as it becomes evident that the employee will be 
engaged in the task for more than four hours during the shift.
    Updating Table 1. Commenters, including LHSFNA, BAC, BCTD, Charles 
Gordon, and James Hardie Building Products, Inc., suggested that the 
utility of Table 1 will diminish over time if OSHA has no mechanism to 
include new control methods that may be developed (e.g., Document ID 
4207, pp. 2-3; 4219, pp. 20-21; 4223, pp. 98-102; 3588, Tr. 3792-3793; 
2322, pp. 21-23).
    Commenters also provided specific recommendations for the frequency 
at which OSHA should update Table 1 and the process by which OSHA 
should do so. James Hardie Building Products, Inc. commented that 
additional controls demonstrated to maintain or increase employee 
protection should be incorporated by reference whenever they become 
available ``without the need to undergo a formal rulemaking process'' 
(Document ID 2322, pp. 21-22). The National Consumers League and the 
American Public Health Association suggested that OSHA consider 
updating Table 1 periodically (e.g., every five years) and publish a 
direct final rule to adopt a revised Table 1 when NIOSH deemed new dust 
control technology effective and feasible (Document ID 2373, p. 3; 
2178, p. 3). Similarly, the Center for Effective Government urged OSHA 
to review Table 1 every five years and make revisions when new control 
technologies are found to be technologically and economically feasible 
(Document ID 3586, Tr. 3319).
    Other commenters urged OSHA to consider mechanisms to update Table 
1 without going through the rulemaking process. NIOSH suggested that 
the Agency develop a database of control technologies to supplement 
those on Table 1, rather than initiate rulemaking to update Table 1 
(Document ID 2177, Attachment B, pp. 20-21). LHSFNA suggested that OSHA 
post enforcement decisions based on objective data online and permit 
employers performing similar tasks to use the controls specified in 
those decisions to meet their obligations under Table 1 (Document ID 
4207, pp. 2-3). Holes Incorporated argued that Table 1 should be 
amendable by employers when testing proves that using such controls 
would ensure compliance with the PEL (Document ID 3441, p. 12; 3580, 
Tr. 1491).
    IUOE, BCTD, and BAC argued that Table 1 should be an appendix to 
the rule so that it can be more easily updated (Document ID 2262, pp. 
48-49; 2329, p. 6; 2371, Attachment 1, pp. 30-31). BCTD offered an 
approach for updating Table 1 that relied on the Agency establishing a 
mechanism for employers, equipment manufacturers, and others to submit 
data to the Agency for evaluation and subsequent inclusion in future 
versions of Table 1. BCTD proposed:

    OSHA could publish the criteria in a non-mandatory appendix to 
the standard, so employers, manufacturers and researchers would have 
a clear understanding of what they will have to demonstrate to get 
their proposed controls onto the table.
    Interested parties could then request that OSHA evaluate a 
control option, supporting their request with objective data, peer-
reviewed studies, reports by NIOSH or other governmental agencies, 
or other reputable sources. If OSHA determined, based on the 
supporting data, that the technology meets its criteria for 
inclusion on Table 1, OSHA would issue an interpretative letter to 
that effect and/or issue a compliance directive advising its 
compliance officers that employers that fully and properly implement 
the particular control should be treated as if they were in 
compliance with the requirements of Table 1. This approach would 
enable OSHA to continually add to the options employers can utilize 
as new technologies come on-line, while at the same time ensuring 
that these additional controls meet the Agency's criteria (Document 
ID 4223, p. 100).

    Charles Gordon also provided a detailed suggestion for the addition 
of regulatory text to address the issue of updating Table 1:

    Updating controls. (i) Three years from the effective date of 
this standard and every 3 years thereafter, OSHA shall request 
comments on new or improved engineering controls which can achieve 
the PEL or Action Level without supplementary respirator use for 
operations specified in Table 1 or other operations not in Table 1 
that have crystalline silica exposure over the Action Level.
    (ii) If OSHA concludes that a new control will achieve the PEL 
without supplementary respirator use, it shall publish a notice 
permitting that control to be used for that Table 1 operation along 
with the other permitted controls or publish a direct final rule 
including that other operation in Table I and permitting the use of 
that control.
    (iii) If a commenter submits to OSHA an engineering control for 
an operation in Table 1, which can achieve the action level without 
supplementary respirator use based on valid studies and cost data 
showing it is feasible, then no later than the date specified in 
paragraph (f)(6)(i), OSHA shall publish a proposal, proposing that 
that engineering control be the required engineering control for 
that operation (Document ID 4236, Appendix 1, p. 1).

    Based on the comments and perspective reflected in the rulemaking 
record, OSHA sees the value in periodically updating Table 1 and is 
concerned that a static Table 1 may discourage innovation in the 
development of control technologies for reducing silica exposure. 
However, while OSHA may certainly consider future updates or 
adjustments to Table 1 if warranted, it will likely need to accomplish 
substantive changes through additional rulemaking. In any event, it has 
no intention to bind a future Administration to such rulemaking, 
whether to update Table 1 in particular or the entire rule in general, 
according to a schedule built into this rule. Meanwhile, the need to 
revise Table 1 in the future should be limited since the controls 
specified--primarily wetting the dust or ventilating and collecting the 
dust--are stated in general terms that will not be rendered obsolete 
by, for example, design improvements to water spraying or vacuuming 
equipment.
    Even if the proposed mechanisms are consistent with the law 
governing rulemaking, OSHA is unwilling to specify a mechanism for 
updating Table 1 for several reasons. First, the procedures outlined by 
BCTD and Charles Gordon would commit the Agency to spend future 
resources to accept a large volume of information from interested 
parties, evaluate it in a timely manner, and prepare the needed 
economic and technological feasibility analysis and other rulemaking 
documents. OSHA may have higher rulemaking priorities and demands on 
its resources at that time, however. Second, Table 1 cannot both 
contain enforceable means of compliance and also be contained in a non-
mandatory appendix. To ensure that employers who do not conduct 
exposure monitoring comply fully with the Table 1 provisions, OSHA must 
include the control specifications of Table 1 in the final standard for 
construction as requirements rather than as non-mandatory 
recommendations. Third, the

[[Page 16728]]

controls specified on Table 1 are flexible and not tied to existing 
technology. The controls specified on Table 1 provide for the use of 
wet methods, ventilation, and in some cases, isolation. OSHA did not 
provide specific criteria for ventilation systems (size, air flow rate, 
etc.) or water flow rates. Instead, OSHA specifies that employers must 
operate the tools with integrated dust controls in accordance with the 
manufacturer's instructions. These instructions provide flexibility to 
take advantage of advances in technology. For example, as manufacturers 
develop effective surfactants to be used with water to further reduce 
silica exposure, there will be no need for OSHA to update Table 1 to 
specifically allow employers to use them. The requirement to use wet 
methods would still be satisfied.
    Thus, OSHA rejects the suggestions to establish a specific 
mechanism for updating Table 1 in the future. If significant 
technological advances occur that require OSHA to initiate rulemaking 
in order to incorporate emerging technology not already encompassed by 
this rule, it will do so in the context of its rulemaking priorities at 
that time. Of course, interested parties may petition the Agency at any 
time to modify the dust control specifications on Table 1 of the 
standard for construction, and OSHA will consider such petitions based 
on the likely benefit that will accrue to workers and the Agency's 
available resources at the time.
    Comparison with consensus standards. The requirements in paragraph 
(c) of the standard for construction are generally consistent with ASTM 
E 2625-09, the national consensus standard for controlling occupational 
exposure to respirable crystalline silica in construction. The ASTM 
standard provides a task-based control strategy, including five tables 
that specify control measures and respiratory protection for common 
construction equipment and tasks. While the ASTM standard provides this 
task-based control strategy, it also applies the PEL and exposure 
assessment to these tasks, as OSHA did in its proposal. However, OSHA's 
final standard for construction, as discussed above, takes a different 
approach by requiring specific engineering controls, work practices, 
and respiratory protection for construction tasks on Table 1; where 
employers fully and properly implement the engineering controls, work 
practices, and respiratory protection specified on Table 1, compliance 
with Table 1 is in lieu of the performance-oriented approach involving 
a PEL and exposure assessment, as provided as an alternative exposure 
control method in paragraph (d) of the standard for construction. 
Additionally, there are numerous differences between the tasks listed 
and the engineering controls, work practices, and respiratory 
protection specified on OSHA's Table 1 and those included on ASTM's 
tables. The ASTM standard also does not divide tasks according to 
duration and does not apply the approach to tasks limited to 90 minutes 
total time. The differences between OSHA's standard and the consensus 
standard, including those in the overall approach to compliance and in 
the format of Table 1, the tasks listed, and the engineering controls, 
work practices, and respiratory protection specified, best reflect the 
evidence received into the rulemaking record and the realities of the 
construction industry. These differences will also enhance compliance 
with OSHA's standard in the construction industry and, in doing so, 
better effectuate the purposes of the OSH Act and protect employees in 
the construction industry from the significant risks posed by exposures 
to respirable crystalline silica.
    Table 1 entries. Table 1 identifies 18 common construction 
equipment/tasks known to generate high exposures to respirable 
crystalline silica. For each kind of equipment/task identified, Table 1 
specifies appropriate and effective engineering controls, work 
practices, and, when necessary, respiratory protection. As proposed, 
Table 1 listed 13 construction operations that expose employees to 
respirable crystalline silica and identified control strategies and 
respiratory protection that reduce those exposures. OSHA received many 
specific comments about particular entries on Table 1 and on the 
specified engineering controls, work practices, and respiratory 
protection included for each entry. The additional equipment/tasks 
included on Table 1 of the final rule for construction are handheld 
power saws for cutting fiber-cement board (with blade diameter of 8 
inches or less) and rig-mounted core saws and drills. Other entries on 
Table 1 of the final standard for construction were broken out from 
those proposed and added as separate entries. These include dowel 
drilling rigs for concrete (included under ``Operating Vehicle-Mounted 
Drilling Rigs for Concrete'' on proposed Table 1), walk-behind milling 
machines and floor grinders (included under ``Milling'' on proposed 
Table 1), small drivable milling machines (included under ``Milling'' 
on proposed Table 1), large drivable milling machines (included under 
``Milling'' on proposed Table 1), heavy equipment and utility vehicles 
used to abrade or fracture silica-containing materials or used during 
demolition activities involving silica-containing materials (included 
under ``Heavy Equipment During Earthmoving'' on proposed Table 1), and 
heavy equipment and utility vehicles for tasks such as grading and 
excavating, but not demolishing, abrading, or fracturing silica-
containing materials (included under ``Heavy Equipment During 
Earthmoving'' on proposed Table 1). One entry on Table 1 of the final 
standard for construction, vehicle-mounted drilling rigs for rock and 
concrete, is the result of combining two entries from proposed Table 1 
(``Operating Vehicle-Mounted Drilling Rigs for Rock'' and ``Operating 
Vehicle-Mounted Drilling Rigs for Concrete''). One proposed entry, 
``Drywall Finishing,'' was not included on Table 1 of the final 
standard for construction. A discussion of each of the 18 Table 1 
entries in the construction standard, including the comments received 
and the changes made from the proposed Table 1 entries, follows below 
in the order in which they appear on Table 1.
    Stationary masonry saws. Stationary masonry saws are used in the 
construction industry to cut silica-containing masonry materials such 
as bricks, concrete blocks, stone, and tile (see Section 5.7 of Chapter 
IV of the FEA). They are mounted either on a table-top or a stand, and 
include a flat platform where the work piece (e.g., a brick) sits 
before the worker brings a rotating circular abrasive blade into 
contact with the work piece by either pressing a swing arm mounted 
blade onto the piece or by moving the piece on a sliding platform into 
contact with a fixed blade (Document ID 4073, Attachment 4a, Rows 42-
48, 55-63, 179-188, 288-297, 343-351). The cutting surface is about 
waist-high and at arm's length from the worker's breathing zone. A 
nozzle for spraying water is usually attached near the blade, and is 
connected to a water basin of some kind via a hose.
    When using stationary masonry saws, paragraph (c)(1)(i) of the 
standard for construction requires that saws be equipped with an 
integrated water delivery system that continuously feeds water to the 
blade and that the tool be operated and maintained in accordance with 
manufacturer's instructions to minimize dust emissions. Saw designs 
vary between manufacturers and, as with other operating parameters, 
manufacturer's recommendations for optimizing wet methods are likely to 
vary somewhat with the saw size and

[[Page 16729]]

design. OSHA is not specifying a minimum flow rate; based on the 
evidence in the record, OSHA anticipates that the water flow rate 
specified by the manufacturer will optimize dust reduction. OSHA 
recognizes that the employer's best available information for reducing 
dust with a specific control comes from the manufacturer's operating 
instructions. This is why OSHA is requiring the saw be operated and 
maintained according to the manufacturer's instruction to minimize 
dust.
    The language describing the required control for stationary masonry 
saws was revised from the proposed rule to clarify that water must be 
continuously applied to the blade, and language was added to require 
that manufacturer's instructions be followed. This reflects OSHA's 
intent that employers use a saw with integrated water delivery system 
supplied by the saw manufacturer. OSHA finds that systems that are 
developed in conjunction with the tool are more likely to control dust 
emission effectively by applying water at the appropriate dust emission 
points based on tool configuration, and not interfere with other tool 
components or safety devices. These include free-flowing water systems, 
with or without a pump and basin, that are designed for blade cooling, 
as well as manufacturer systems designed for dust suppression alone 
(Document ID 1555, p. 509; 3998, Attachment 12a, pp. 9, 15-16; 3998, 
Attachment 12e, p. 3).
    The proposed entry for stationary masonry saws also included a note 
requiring that water be changed frequently to avoid silt build-up in 
water and that the blade not be excessively worn. CISC commented that 
terms such as these were too ambiguous and would thus prevent the table 
from being a realistic compliance option (Document 2319, p. 98). OSHA 
understands that these notes could be subject to interpretation and in 
response, has removed the notes from Table 1. However, these practices 
are often included in manufacturer's instructions, and OSHA considers 
these type of instructions to be part of fully and properly 
implementing engineering controls (e.g., Document ID 4073, Attachment 
4a, Rows 59-61).
    In the FEA, OSHA's exposure profile for stationary masonry saws 
shows that wet cutting is an effective dust control. The median 8-hour 
TWA exposure in the profile is 34 [mu]g/m\3\ for workers using saws 
with water delivery systems (Table IV-5.7-B in Section 5.7 of Chapter 
IV of the FEA) and the mean exposure for wet cutting is 41 [mu]g/m\3\, 
substantially lower than the mean of 329 [mu]g/m\3\ for dry cutting 
operations, a disparity that affirms that use of water on stationary 
saws significantly reduces exposure to respirable crystalline silica. 
Additional field data also show the effectiveness of water to control 
respirable crystalline silica exposures during cutting. Flanagan et 
al., in their 2006 study and 2009 data set, found that wet cutting 
methods (details not available) were associated with markedly lower 
exposure levels than were reported for all workers using table-mounted 
saws (Document ID 0677; 0677, Attachment 2). The silica concentrations 
reported by Flanagan et al. over the sampling period (ranging from 12 
to 505 minutes) when wet cutting ranged from 6 [mu]g/m\3\ to 316 [mu]g/
m\3\, with a mean of 73 [mu]g/m\3\ and median of 46 [mu]g/m\3\ 
(Document ID 0677; 0677, Attachment 2). Since most of the sample 
durations in this dataset were less than 360 minutes, workers' 8-hour 
TWA exposures were even lower. These data also included indoor work.
    In addition to these field results, the record includes 
experimental studies that examined the effectiveness of wet dust 
control systems. Meeker et al. (2009) compared intensive masonry 
cutting done without controls to exposures while using saws with 
integrated water delivery systems and maximum flow rates of 2.3 and 2.4 
liters per minute (0.6 and 0.63 gallons per minute) and found that wet 
saws were associated with a 91 percent reduction in exposure to 
respirable quartz (Document ID 803, p. 1; 2177, Reference 11, pp. 104, 
107-108). Carlo et al. (2010) found reduction rates of 99 percent in 
the respirable dust exposure when water was applied at the 
manufacturer-recommended water flow rate, compared to dry cutting 
(Document ID 3612, pp. 246-247, 249). While respirable dust reductions 
do not always translate to exactly the same percent reduction in 
respirable silica levels, OSHA finds that respirable dust reductions 
are a reliable indicator of the capability of the control to reduce 
respirable silica. Therefore, OSHA anticipates that the control 
discussed in Carlo et al. (2010) would result in significant reductions 
to silica exposures.
    CISC questioned the appropriateness of requiring an integrated 
water delivery system when most integrated systems are intended to keep 
the blade cool and are not designed for dust suppression (Document ID 
2319, p. 109). However product literature submitted to the docket from 
five major saw manufacturers (Andreas Stihl, Husqvarna, Hilti, Makita 
USA, and Wacker Group) highlights the use of water application 
equipment to suppress dust in addition to blade cooling (Document ID 
3620, pp. 6, 10, 24, 30; 3998, Attachment 12a, pp. 9, 15-16; 3998, 
Attachment 12e, p. 3; 3998, Attachment 12f; 3998, Attachment 12h; 4233, 
Attachment 1, p. 6). Beamer et al. (2005) conducted experiments to 
observe the differences in the various wet cutting methods available 
and found that the greatest improvement in dust reduction occurred with 
freely flowing water applied at a rate of 48 gallons per hour (0.8 
gallons per minute), resulting in dust reduction of about 93 percent 
and confirming the benefits of water flowing over the stationary saw 
cutting blade compared with other misting systems (Document ID 1555, p. 
509). Therefore, based on the evidence in the record, OSHA has 
determined that stationary masonry saws equipped with an integrated 
water delivery system are effective and the best available technology 
for controlling respirable crystalline silica.
    Several commenters suggested that OSHA include an option for dry 
cutting on Table 1 (i.e., using LEV or other non-wet methods to control 
dust) because wet methods were not always available and certain 
materials are required to be cut dry. Commenters explained that 
freezing temperatures, lack of available water sources on new 
construction sites, concerns of water damage to surrounding areas 
during indoor work and problems with discoloration or water staining 
materials were all reasons why an employer may elect to cut without 
water (Document ID 0861, p. iv; 1431, pp. 1-6-1-9; 2296, p. 31; 2319, 
p. 94; 2320, pp. 6-7; 3587, Tr. 3609-3610; 4220, p. 5).
    OSHA addresses the issue of freezing temperatures and availability 
of water in the technological feasibility analysis (Chapter IV of the 
FEA) and has determined that these barriers can be overcome in most 
instances, for example by wrapping gutter heat tape around drums of 
water or adding environmentally-friendly antifreeze additives to water 
(e.g., Document ID 3589, Tr. 4214, 4230). Moreover, evidence in the 
record indicates that LEV is not as effective as wet methods for 
controlling silica dust emissions from stationary saws. In the only 
study available to OSHA that directly compared wet dust suppression 
with LEV under the same experimental conditions, Carlo et al. (2010) 
determined that, even though the use of LEV resulted in substantial 
respirable dust capture, the water application system reduced the dust 
to a greater extent, reducing respirable dust levels by a factor of 10 
more than the LEV systems tested (Document ID 3612, pp.

[[Page 16730]]

247-250). Unlike for wet dust control systems, there is little evidence 
in the record that LEV systems have proven effective in actual field 
use; the database compiled by Flanagan et al. contains no sample 
results from using stationary saws with LEV (Document ID 0677, 
Attachment 2).
    OSHA finds that the study by Carlo et al. indicates that LEV 
systems on stationary saws are not as effective as water-based dust 
suppression systems and that respiratory protection will likely be 
needed. In the PEA, OSHA acknowledged that there was some evidence that 
exposures could be reduced to or below 50 [mu]g/m\3\ with LEV when saws 
were used for typical cutting periods (15 to 30 percent of the shift) 
but that the effectiveness of LEV systems for stationary saws had not 
been widely evaluated. However, no evidence came into the record after 
the PEA that would allow OSHA to have greater confidence in the use of 
LEV when dry cutting or to consider it to be as effective as wet 
cutting in reducing silica dust exposure. Therefore, OSHA has not 
included a control alternative for the use of dry cutting with LEV in 
Table 1, and is only allowing integrated water systems for compliance 
with Table 1.
    OSHA understands that there may be limited situations where the use 
of wet systems is not feasible for a given application. For those 
situations, the employer may use other means of dust control such as 
LEV systems, but the employer must then follow paragraph (d) rather 
than paragraph (c) of the standard for construction, i.e., comply with 
the 50 [mu]g/m\3\ PEL, perform exposure assessments to determine 
compliance with the PEL, and supplement the engineering and work 
practice controls with respiratory protection where the PEL is not 
being met.
    Stationary masonry saws with integrated water systems are readily 
available from several manufacturers including EDCO, Andreas Stihl, 
Hilti, Makita USA, Husqvarna, Wacker Group, MK Diamond, and Bosch (for 
tile cutting) and are effective and the best control option available 
(Document ID 4073, Attachment 4a, Rows 59-63, 183-188, 292-297, 347-
351, 417-419; 4073, Attachment 4b, pp. 10-12, 21; 3998, Attachment 12a; 
3998, Attachment 12e; 3998, Attachment 12f; 3998, Attachment 12g; 3998, 
Attachment 12h). Therefore, OSHA has determined that an integrated 
water delivery system is the appropriate control for inclusion on Table 
1.
    In the proposed rule, OSHA required the use of a half-mask 
respirator for employees who operated stationary masonry saws for more 
than four hours. OSHA made this determination based on the highest 
exposure results included in its exposure profile. OSHA has since 
determined that when fully and properly implementing all of the 
provisions under paragraph (c), employees can operate stationary 
masonry saws without the use of respirators. This is supported by the 
exposure profile contained in Table 5.7-B in Section 5.7 of Chapter IV 
of the FEA, which shows a mean exposure of 41 [mu]g/m\3\, a median of 
34 [mu]g/m\3\ and 75 percent of the sample results below 50 [mu]g/m\3\. 
Flanagan et al. reported similar exposures with a mean exposure of 48 
[mu]g/m\3\ crystalline silica from four exposure samples taken while 
workers operated saws indoors or in enclosed areas (Document ID 0677, 
Attachment 2). While water use was not described in any detail, these 
data show that exposures can be consistently maintained at a level 
where respiratory protection is not needed. Therefore, the final rule 
does not require the use of respiratory protection when employers are 
using wet stationary saws in accordance with Table 1, even when 
stationary masonry saws are used indoors or in otherwise enclosed areas 
(situations which are the most likely to generate high exposures).
    Handheld power saws (any blade diameter). In the proposed rule, 
this entry was listed as ``Using Handheld Masonry Saws.'' OSHA has 
changed the title of this entry in the final rule to clarify that the 
requirements in Table 1 apply to any use of handheld power saws, not 
just those involving masonry materials. However, the tools included 
under this entry have not changed and include cut-off, chop, quickie, 
and handheld masonry saws.
    Handheld power saws are used in the construction industry for 
cutting a variety of materials (see Section 5.6 of Chapter IV of the 
FEA). They usually consist of a semi-enclosed circular blade, directly 
adjacent to or in front of two handle grips which are perpendicular to 
each other. The blade enclosure covers the half (or more) of the blade 
directly facing the worker. A worker typically will use the blade to 
cut a work piece (e.g., a brick) placed on the ground by starting the 
device and slowly lowering the entire handheld saw with both hands to 
the work piece until the rotating blade makes contact and begins to 
cut, at which point the worker applies pressure to the work piece and 
cuts appropriately (Document ID 4073, Attachment 4a, Row 47). A nozzle 
for spraying water is usually located near the blade, and a water 
source is usually connected to the saw from a water source via a hose 
(Document ID 3998, Attachment 12e; 3998, Attachment 12f; 3998, 
Attachment 12h, pp. 10-11).
    When using handheld power saws with any blade diameter (except saws 
used to cut fiber-cement board), paragraph (c)(1)(ii) of the standard 
for construction requires that saws be equipped with an integrated 
water delivery system that continuously feeds water to the blade and 
that it be operated and maintained in accordance with manufacturer's 
instructions to minimize dust emissions. Like stationary saws, designs 
vary between manufacturers and, as with other operating parameters, 
recommendations for optimizing wet methods are likely to vary somewhat 
with the saw size and design. In light of these variables, OSHA is not 
specifying a minimum flow rate. In addition, OSHA is recognizing that 
the employer's best available information for reducing dust with a 
specific control comes from the manufacturer's operating instructions, 
which is why OSHA is requiring the saw be operated and maintained 
according to the manufacturer's instructions to minimize dust. Water-
fed handheld saws are commercially available from a variety of sources 
(Document ID 0615; 0737; 3998, Attachment 12e; 3998, Attachment 12a; 
3998, Attachment 12f; 3998, Attachment 12g; 3998, Attachment 12h).
    The data in the record and the studies reviewed by OSHA demonstrate 
that water spray suppression systems reduce respirable crystalline 
silica exposures substantially where the system was well designed and 
properly implemented and maintained (Document ID 0868; 1181; 3497; 
3610; 3777; 4073, Attachment 8a). Use of an integrated water delivery 
system on the cut-off, chop, quickie or masonry saws has been shown to 
reduce respirable dust exposures by 78-96 percent (Document ID 0868, p. 
v; 1181, p. 443; 3610, p. 157; 3777, p. 67). Data compiled by the CSDA 
from member jobsites as well as NIOSH documents showed that all outdoor 
hand sawing using a saw equipped with a water supply produced exposure 
levels below a TWA of 50 [mu]g/m\3\ (Document ID 3497, p. 5).
    In a laboratory study, Thorpe et al. (1999) evaluated the 
effectiveness of two types of water supplies commonly used with 
handheld saws: (1) A pressurized portable water supply and (2) a 
constant water supply (Document ID 1181, pp. 443, 445-447). During this 
evaluation, 15-minute PBZ samples were collected during uncontrolled 
and controlled (i.e., water-fed) cutting of concrete slabs containing 
20 percent to 40 percent

[[Page 16731]]

silica (i.e., worst-case conditions) (Document ID 1181, p. 447). The 
study protocol involved short sampling durations because handheld saws 
are typically used intermittently to make short cuts. The uncontrolled 
mean silica concentration during multiple 15-minute trials of intensive 
cutting ranged from 1,700 [mu]g/m\3\ to 4,800 [mu]g/m\3\ (reported as 
1.7 to 4.8 mg/m\3\) (Document ID 1181, p. 448). Reductions in exposure 
to respirable silica dust when cutting concrete slabs using wet methods 
compared with no controls were 75 percent for diamond blades and 94 
percent for resin blades when using water supplied by mains, and 75 
percent for diamond blades and 77 percent for resin blades when using 
water supplied by a portable tank. Both sources of water were effective 
at reducing respirable dust, however, the portable tank needed to be 
periodically re-pressurized to maintain the necessary flow rate, while 
the water supplied from the mains provided a more constant flow rate. 
Both types of systems used to supply water to an integrated water 
delivery system would be acceptable under the table.
    NIOSH also evaluated the performance of a commercially available 
water backpack and spray attachment, pre-set by the attachment 
manufacturer to provide 1.4 liters per minute water consumption (0.36 
gallons per minute) for handheld saws during concrete block cutting 
(Document ID 0868, pp. 8, 11). The handheld electric abrasive cutter 
was used outdoors to make cuts through concrete blocks laid lengthwise 
on a plank 17 inches above the ground. During the 5- to 10-minute 
trials with water-fed saws, the water spray attachment reduced quartz 
exposures by an average of 90 percent from uncontrolled levels 
(Document ID 0868, p. 10). Middaugh et al. (2012) conducted a workplace 
field study to evaluate the effectiveness of dust controls on cut-off 
saws (Document ID 3610, p. 158). Air sampling was conducted for 10 days 
at 5 job sites on 4 experienced operators using gas-powered cutoff saws 
with 14 inch (35.6mm) diameter blades to cut concrete curbs (Document 
ID 3610, p. 159). Air sampling was conducted both with and without wet 
methods; sampling ranged from 4 to 16 minutes and corresponded to the 
entire duration of the task (Document ID 3610, pp. 159-161). With wet 
suppression, the concentration of respirable silica levels was reduced 
78 percent to 210 [mu]g/m\3\ (Document ID 3610, p. 162).
    Based on the information in the record, OSHA concludes that most of 
the time, handheld power saw operators use the saw for two hours or 
less over the course of a workshift, typically using handheld saws for 
brief, intermittent periods repeated numerous times over the course of 
a shift (Document ID 1431, p. 3-63). The Mason Contractors Association 
of America stated that ``90 minutes is actually a really long time to 
be cutting something. The vast majority of [cutting tasks] are under 15 
minutes [total] in any given day'' (Document ID 3585, Tr. 2911). The 
Bay Area Roofers Waterproofers Training Center agreed, clarifying that 
when cutting is performed as part of its work it is usually half an 
hour to 45 minutes a day (Document ID 3581, Tr. 1598). Information 
contained in research supports this as well. Thorpe et al. (1999) used 
15-minute sampling durations in the study protocol because handheld 
saws are typically used intermittently to make short cuts (Document ID 
1181, pp. 447-448). Middaugh et al. (2012) explained that concrete 
cutting in roadway construction is frequently performed with a handheld 
saw, noting that ``although some applications may require cutting for 
an entire 8-hour workday, typical cutting is performed for less than 
two hours per day'' (Document ID 3610, p. 162). Sample times from the 
Flanagan et al. database support this; the median time for using 
handheld portable saws was 101 minutes and the range of cutting times 
was from 9 to 447 minutes, indicating that saws are typically used for 
only a portion of the shift, although some workers cut for longer 
durations (Document ID 0677, Attachment 2).
    Estimated TWA exposures (i.e., averaged over eight hours) using 
task measurements from field studies may exceed 50 [mu]g/m\3\ when 
workers cut with water for two or more hours per day (Document ID 3610; 
4073, Attachment 8a, p. 1; 0868). Shepherd and Woskie (2013) estimated 
that if typical cutting conditions (intensive cutting) were performed 
outdoors with wet methods for two hours and no other exposure occurred 
for the remainder of the day, 83 percent (88 out of 106) of the saw 
operators' 8-hour TWA exposures would be 50 [mu]g/m\3\ or less 
(Document ID 4073, Attachment 8a, p. 1). In further analysis, the 
authors considered what would happen if operators used the water-fed 
saws outdoors at this same level of intensity for a full 6 hours of the 
shift, in which case 61 percent of operators would have 8-hr TWA 
exposures of 50 [mu]g/m\3\ or less (Document ID 4073, Attachment 8a, p. 
1).
    In the proposal, OSHA based its requirement to use respiratory 
protection for operating saws more than four hours per shift on the few 
higher exposure values in its exposure profile, which indicated that 
exposures would exceed 50 [mu]g/m\3\ occasionally when wet cutting with 
portable saws. However, OSHA concludes that the study by Shepherd and 
Woskie (Document ID 4073, Attachment 8a) as well as other material 
contained in the record and discussed above provide a better basis on 
which to determine the need for respiratory protection. Based on these 
studies, OSHA determined that outdoor wet cutting for more than four 
hours could result in more frequent exposures over 50 [mu]g/m\3\ than 
are experienced with shorter task durations. Therefore, paragraph 
(c)(1)(ii) of the standard for construction requires use of respiratory 
protection having an APF of at least 10 for employees using a handheld 
power saw of any blade diameter equipped with an integrated water 
delivery system for more than four hours per shift. When cutting for 
four hours or less outdoors, no respiratory protection is required.
    The vast majority of samples reviewed by OSHA involve the use of 
handheld saws outdoors. However, employees may occasionally use 
handheld saws indoors. When an employee uses a water-based system 
indoors or within enclosed areas, elevated exposures can still occur 
(Document ID 0675; 0177; 0846; 3497; 3777). Data submitted by CSDA 
shows that almost all indoor hand sawing using wet methods produced 
exposure levels above 50 [mu]g/m\3\ (Document ID 3497, pp. 1-4, 6, 8). 
Additionally, a field study of wet sawing found that an enclosed 
location (in a large garage building open in front and closed on 3 
sides) resulted in significantly higher exposures than when the work 
was done outdoors (Document ID 3777, p. 1); a separate study found 
levels as high as 240 and 260 [mu]g/m\3\ during indoor wet sawing 
(Document ID 0675, p. 1098). OSHA's exposure profile contained in 
Section 5.6 of Chapter IV of the FEA shows that using wet methods 
indoors results in higher exposures when compared to outdoor cutting 
with only 50 percent of the exposures in indoor environments being 50 
[mu]g/m\3\ or less, compared to 80 percent of the outdoor wet sawing 
samples. Although wet methods substantially reduce operator exposures 
compared to uncontrolled dry cutting indoors, elevated exposures still 
occur routinely. To reduce these exposures, OSHA is requiring that work 
done indoors or in enclosed areas have

[[Page 16732]]

additional general ventilation such as exhaust trunks, fans, air ducts 
or other means of forced air ventilation to prevent the accumulation of 
dust in the work area. Accordingly, for indoor work, paragraph 
(c)(1)(ii) requires the use respiratory protection with an APF of 10 
regardless of task duration.
    Representatives from the roofing industry expressed concern 
regarding the use of wet methods in their industry, citing primarily 
the potential increase in slips and falls from introducing water to 
elevated worksites (Document ID 2320, p. 116; 2192, p. 4; 3526, p. 7). 
The Tile Roofing Institute stated that in California and Arizona, 
rooftop operations with roofing tiles or pavers are given an exemption 
from the requirement to use a dust reduction system because there is no 
way to address both the silica and fall protection hazard (Document ID 
3587, Tr. 3595). Conversely, testimony from the public hearings 
indicates that wet dust control systems can be used to reduce exposures 
to silica during cutting of roofing tiles and pavers. Dan Smith, 
director of training for the Bay Area Roofers and Waterproofers 
Training Center, testified that the roofing industry in California is 
starting to voluntarily cut roofing tiles and pavers wet (Document ID 
3581, Tr. 1600-1601; 1638) and that use of controls may actually 
increase visibility, thereby reducing a potential fall hazard (Document 
ID 3581, Tr. 1603-1604). He also explained that dry cutting of roofing 
tiles is prohibited in the U.K., and that the contractors association 
(the National Federation of Roofing Contractors), ``. . . provides 
guidance and training. They use wet saws on scaffolding at the roof 
level . . . they use a [water] mister on the tile saw. They use a 
system like the hytile . . . which is a tile breaking tool'' (Document 
ID 3581, Tr. 1601).
    OSHA understands the concerns expressed by representatives from the 
roofing industry regarding the use of wet methods and increased risk 
for falls; however, OSHA concludes that alternate project planning can 
enable employers to use wet methods by implementing some of the 
measures described above.
    In the proposed rule, OSHA included an option under Table 1 for the 
use of LEV when using portable masonry saws. While including LEV as an 
alternative to wet methods in the table was supported by both labor and 
industry groups (Document ID 2296, p. 32; 4223, p. 140; 4233, 
Attachment 1, p. 1), OSHA has removed this option from Table 1 based on 
information contained in the record indicating that LEV cannot 
consistently maintain exposure at or below a TWA exposure level of 50 
[mu]g/m\3\ (see Section 5.6 of Chapter IV of the FEA). OSHA is not 
prohibiting use of LEV for dry cutting, as LEV may be effective in 
reducing exposure to or below 50 [mu]g/m\3\ in situations where, for 
example, saw use is intermittent. Employers who choose to do so may 
still use LEV in lieu of an integrated water system; however, those 
employers would be required to comply with the PEL and exposure 
assessment requirements under paragraph (d) of the standard for 
construction.
    Handheld power saws for cutting fiber-cement board (with blade 
diameter of 8 inches or less). These specialized saw configurations 
consist of blades (with four to eight teeth) specifically designed for 
cutting fiber-cement board (see Section 5.6 of Chapter IV of the FEA) 
(Document ID 2322, p. 9; 2322, Attachment B, p. 8). The blades are 
fitted to a circular saw (or occasionally to other saws) with dust 
reduction systems (Document ID 2322, p. 9; 2322, Attachment B, p. 36). 
These saws have been specifically designed and tested by a member of 
the fiber-cement siding industry and by NIOSH for controlling the 
silica exposure of installers who perform cutting in that industry, and 
the saw is intended specifically for use on fiber-cement board 
(Document ID 2322, pp. 5, 9; 2322 Attachment B, pp. 33, 36).
    When using handheld power saws with a blade diameter of 8 inches or 
less for cutting fiber-cement board outdoors, paragraph (c)(1)(iii) of 
the standard for construction requires saws to be equipped with a 
commercially available dust collection system that provides the air 
flow recommended by the manufacturer and a filter with a 99 percent or 
greater efficiency, operated in accordance with the manufacturer's 
instructions to minimize dust emissions. OSHA is not providing an entry 
for use of these saws indoors on Table 1 because fiber-cement board, 
used as siding and fascia applied to the exterior of buildings, is 
usually cut outdoors and the record lacks information on exposures to 
silica that would result from cutting fiber-cement board indoors. 
Therefore, employers who choose to operate saws to cut fiber-cement 
board indoors must conduct exposure assessments and comply with the PEL 
in accordance with paragraph (d) of the standard for construction.
    This entry was added to Table 1 of the final standard for 
construction in response to comments NIOSH and the fiber-cement board 
industry submitted to the rulemaking record. These submissions provided 
substantial data on control technology (a specially configured saw) for 
controlling silica exposure when saw operators cut fiber-cement board 
(Document ID 2177, Attachment B, pp. 17-19; 2322, Attachment B-E and 
H).
    The James Hardie Building company submitted 75 samples for workers 
using specially configured circular saws (with specialty blades of less 
than 8 inches) for cutting fiber-cement board with LEV (Document ID 
2322, pp. 19-20). These saws were all fitted with cutting blades 
designed for the fiber-cement board product and some form of dust 
collector (but not always designed with vacuum suction). Workers using 
these saws had a mean 8-hour TWA exposure of 11 [mu]g/m\3\ (median 7 
[mu]g/m\3\), although elevated exposures (maximum exposure of 76 [mu]g/
m\3\) occurred with some saw/control configurations that proved less 
reliable (for example, saws attached to a dust receptacle, without the 
benefit of a vacuum dust collection device) (Document ID 2322, pp. 19-
20). Although the cutters sawed fiber-cement board products containing 
15 to 50 percent silica, the respirable dust collected in the samples 
was 0 to 12 percent silica and percentages in the lower half of that 
range were most typical (Document ID 2322, Attachment D, pp. 5-10; 
2322, Attachment E, pp. 5-9; 2322, Attachment F, pp. 5-10). Most of the 
sawyers for whom exposures were elevated cut siding for approximately 
half the shift (four to five hours), a duration representative of 
typical cutting activities during a normal day of fiber-cement siding 
installation (Document ID 2322, Attachment D, p. 16; 2322, Attachment 
E, p. 16; 2322, Attachment F, p. 18). Several NIOSH reports demonstrate 
that this and other saw configurations are effective in achieving 
exposures of 50 [mu]g/m\3\ or below when the saw is used with a vacuum 
dust collector (Document ID 4138; 4139, p. 11; 3998, Attachment 4a; 
3998, Attachment 4b; 3998, Attachment 4c).
    Based on the evidence in the record, commercially available dust 
collection systems for handheld power saws with a blade diameter of 8 
inches or less and a dust collection device providing the air flow 
recommended by the manufacturer have been demonstrated to be 
particularly effective in controlling silica during outdoor cutting of 
fiber-cement board. One type of saw evaluated was a handheld, dust 
collecting model equipped with dust collection device rated at 200 cfm 
over a 7.25-inch-diameter blade (27.5 cfm per inch); however, the 
measured flow rate was reported to be 69 to 106 cfm. Using this 
configuration, all 21 exposure

[[Page 16733]]

samples taken for siding cutters on construction sites were 41 [mu]g/
m\3\ TWA or less (20 sample results were less than 25 [mu]g/m\3\) while 
cutting a variety of fiber-cement board siding products containing up 
to 50 percent silica (Document ID 3998, Attachment 4a; 3998, Attachment 
4b; 3998, Attachment 4c; 4138; 4139). Accordingly, OSHA is requiring in 
paragraph (c)(1)(iii) that dust collectors be used with saws when 
cutting fiber-cement board.
    Based on the evidence in the record, OSHA is not requiring the use 
of respiratory protection when employees are using handheld power saws 
with a blade diameter of 8 inches or less, for cutting fiber-cement 
board outdoors in accordance with Table 1 for any task duration. OSHA 
has determined that in such circumstances, employee exposures will be 
reduced to 50 [mu]g/m\3\ or less when the controls specified for this 
task on Table 1 are fully and properly implemented.
    Walk-behind saws. When using walk-behind saws (see Section 5.6 of 
Chapter IV of the FEA), paragraph (c)(1)(iv) of the standard for 
construction requires that saws be equipped with an integrated water 
delivery system that continuously feeds water to the blade and that the 
tool be operated and maintained in accordance with manufacturer's 
instructions to minimize dust emissions. OSHA is specifying that the 
saws be used with an integrated water feed system because the Agency 
has identified this as the most effective means of reducing exposures 
to respirable crystalline silica. This requirement is essentially the 
same as was proposed for the entry ``Using Portable Walk-Behind and 
Drivable Masonry Saws.'' As explained below, requirements in the final 
rule for drivable saws have been separated from those for walk-behind 
saws.
    Saw designs vary among manufacturers, and as with other operating 
parameters, recommendations for optimizing wet methods are likely to 
vary somewhat with the saw size and design. As with other saws, OSHA is 
not specifying a minimum flow rate, but rather anticipates that the 
water flow rates specified by the manufacturer will optimize dust 
reduction. OSHA recognizes that the employer's best available 
information for reducing dust with a specific control comes from the 
manufacturer's operating instructions, which is why OSHA is requiring 
the saw be operated and maintained according to the manufacturer's 
instructions to minimize dust. Water-fed walk-behind saws (manual and 
self-propelled) are widely available from many manufacturers and 
construction tool distributors, such as Grainger, EDCO, MK Diamond, and 
CS Unitec (Document ID 0715; 1676; 1185; 0643; 0615).
    CSDA stated that ``nearly 100% of CSDA contractors use water on 
each and every job and this has to do with extending the life of the 
expensive diamond tools. The use of water has an additional benefit of 
containing silica particles that could become airborne'' (Document ID 
3496, p. 3). This was supported by others during the public hearings 
(Document ID 3580, Tr. 1438; 3585, Tr. 2885) and in written comments 
(Document ID 2316, p. 3). Disagreeing, both SMI and the Mason 
Contractors Association of America commented that most water-fed 
systems are designed to keep the blade cool, and their ability to 
suppress dust has not been sufficiently researched (Document ID 2316, 
p. 3; 3585, Tr. 2885). CISC similarly asked whether an additional water 
feed is needed for these saws or whether the one currently integrated 
for the purpose of cooling the saw will suffice (Document ID 2319, p. 
104).
    OSHA finds that considerable evidence in the record shows that 
water application reduces dust emissions, and several saw manufacturers 
state that using wet cutting will suppress dust (see discussion about 
requirements for water delivery systems above). Furthermore, the water 
delivery system described in Linch (2002) was for the purpose of 
cooling or protecting the blade, but was effective in suppressing 
respirable silica levels to below 50 [mu]g/m\3\ (Document ID 0784, p. 
216). CSDA submitted exposure data collected during slab sawing with 
saws ``equipped with water supply,'' presumably for blade cooling. 
Those data show that of 26 measurements of silica concentrations taken 
during outdoor work, 21 (80 percent) were less than 25 [mu]g/m\3\, and 
only one sample (65 [mu]g/m\3\) exceeded 50 [mu]g/m\3\ (Document ID 
3497, pp. 2-4). Therefore, OSHA concludes water provided as coolant can 
also control silica exposure.
    CISC questioned the feasibility of using wet methods in situations 
where there is no established water main on site (Document ID 2319, p. 
112). OSHA finds that water tanks, which were used to provide water to 
the walk-behind saws in Linch (2002), are already commonly available on 
many construction sites and could provide water for a walk-behind saw 
(Document ID 0784, pp. 216-217).
    Data contained in the record show that none of the respirable 
silica results associated with wet cutting outdoors using walk-behind 
saws exceeds 50 [mu]g/m\3\, with the majority of these results being 
less than or equal to the limit of detection (Document ID 0784, pp. 
216-217). These results were obtained using the saw's normal water feed 
system intended for cooling the blade. Therefore, OSHA has determined 
that no respiratory protection is required when working outdoors with a 
walk-behind saw for any task duration.
    Since walk-behind saws are used to cut pavement, they are most 
commonly used outdoors, though they can also be used indoors (Document 
ID 1431, pp. 3-63). Although the data are limited, water-fed walk-
behind saws used indoors or in enclosed areas may result in higher 
exposures than those measured outdoors. Studies by both NIOSH and 
Flanagan et al. (2001) noted the potential for elevated exposure when 
walk-behind saws with continuous water application are used indoors, 
with Flanagan et al. reporting four 8-hour TWA sample results between 
65 to 350 [mu]g/m\3\ for four to seven hours of work (Document ID 4233, 
Attachment 1, p. 10; 0675, pp. 1098-1099). Additionally, the CSDA 
report submitted to the record shows the only exposure result from 
indoor slab sawing exceeded 50 [mu]g/m\3\ despite the use of equipment 
with water supply (Document ID 3497, pp. 2-4). These results indicate 
that the source for the elevated exposure is likely due to the build-up 
of respirable aerosol within the enclosed space, rather than direct 
exposure to slurry spray (Document ID 0675, p. 1099). While OSHA 
anticipates that the results for indoor sawing can be reduced by 
minimizing the build-up of dust with supplemental ventilation as 
required under paragraph (c)(2)(i) of the rule, OSHA is unable to 
conclude that exposures can be consistently reduced to 50 [mu]g/m\3\ or 
less for this task when performed indoors. Therefore, when used indoors 
or in an enclosed area, OSHA is requiring the use of respiratory 
protection with an APF of 10 regardless of task duration.
    Drivable saws. Paragraph (c)(1)(v) of the standard for construction 
requires that, when using drivable saws to cut silica-containing 
materials, the saw must be equipped with an integrated water delivery 
system that continuously feeds water to the blade and that the tool be 
operated and maintained in accordance with the manufacturer's 
instructions to minimize dust emissions. Drivable saws include those 
where the operator typically sits in a cab (open or enclosed) away from 
the pavement cut point, guiding the saw to make long cuts such as are 
common for utility installation along roadways. These saws are 
cumbersome to move and are typically only used when

[[Page 16734]]

making long cuts. The blade housed by the vehicle can be large (e.g., 8 
feet in diameter and 2 inches thick) and is usually equipped with a 
water-fed system to cool the blade (Document ID 1431, pp. 3-63--3-64). 
The requirement to use integrated water systems on drivable saws is 
unchanged substantively from the proposal.
    In its Technological Feasibility analysis (see Section 5.6 of 
Chapter IV of the FEA), OSHA analyzes exposures for workers using 
drivable saws. The exposure profile includes three samples, two using 
wet methods as required by Table 1 and one operating under other 
conditions. The two samples taken on workers using wet saws showed TWA 
silica exposures of 12 [mu]g/m\3\ (i.e., below the limit of detection 
(LOD)) and 33 [mu]g/m\3\ over sampling times of 70 and 125 minutes, 
respectively. OSHA considers these exposure results to reflect typical 
work patterns in that operators will often operate the saw for one or 
two hours before moving the saw to another location. CISC questioned 
OSHA's use of short term samples and the assumption of zero exposure 
during the unsampled portion of the shift and noted that this could 
underestimate the exposures for these workers (Document ID 2319, pp. 
51-52). While OSHA acknowledges that this situation may occur at times, 
there is no evidence that this is the case for these drivable saws 
samples. These samples were collected by OSHA inspectors, who are 
instructed to sample for the entire duration of silica exposure. 
Accordingly, OSHA concludes that these samples accurately characterize 
the sampled workers' exposure.
    In the proposed rule, dust control requirements were specified for 
drivable and walk-behind saws together, and the proposed rule would 
have required respirator use when operating either saw in indoor or 
enclosed environments. In the final standard for construction, the 
requirements for these kinds of saws are separated on Table 1 because, 
unlike walk-behind saws, drivable saws are rarely, if ever, used in 
indoor environments. Because the requirements of Table 1 only apply to 
outdoor use of drivable saws, and the data available to OSHA 
demonstrate that the wet methods described above can consistently 
control exposures in that environment, Table 1 does not require the use 
of respiratory protection when these controls are implemented, 
regardless of task duration.
    SMI and CISC commented that currently drivable saws use water to 
cool the cutting tool, and the effectiveness of cooling water for 
respirable crystalline silica dust mitigation has not been 
comprehensively researched (Document ID 2316, Attachment 1, p. 3; 2319, 
p. 112). SMI stated specifically that ``parameters such as flow rate, 
volume, flow delivery characteristics, velocity, and delivery location 
have not been evaluated or compared'' (Document ID 2316, p. 3). 
However, Atlantic Concrete Cutting agreed that all of its cutting 
services were performed with water (Document ID 2367, p. 2), and that 
the application of water minimized and most likely eliminated exposure 
to respirable crystalline silica. Atlantic Concrete Cutting also stated 
that the use of a ``water-fed system that delivers water continuously 
at the cut point'' would be an appropriate silica dust control for 
drivable saws and that respirators would not be needed to further 
protect employees (Document ID 2367, pp. 2-4). In light of this 
testimony, OSHA concludes that it is appropriate to permit employers to 
fully and properly implement water-based systems on drivable saws in 
compliance with Table 1, eliminating their need to conduct exposure 
assessments for employees engaged in a task using drivable saws. 
Moreover, as reflected in Table 1, OSHA concludes that full and proper 
implementation of this control will not require the use of respirators 
for this task even if performed for more than four hours in a shift and 
so has not included respiratory protection for this task.
    Rig-mounted core saws or drills. Paragraph (c)(1)(vi) of the 
standard for construction, an entry for rig-mounted core saws or 
drills, was not included in proposed Table 1. Core saws or drills are 
used to perform core cutting (also called core drilling, boring, or 
concrete coring) to create round holes for pipes, ducts and conduits to 
pass through walls, ceilings and floor slabs made of concrete, masonry 
or other materials that may contain silica (see Section 5.6 of Chapter 
IV of the FEA). Core cutting machines (also called core drills) use a 
thin continuous round cutting surface on the round end of a cylindrical 
coring tool (``bit'') (Document ID 0679, pp. 18-20). The machine is 
typically attached to the surface being drilled (bolted on via a rig 
for stability) (Document ID 3998, Attachment 13e, pp. 4, 9). When the 
rotating diamond core cutting bit is applied to solid material, the bit 
cuts away a thin circle of material. The cut separates the central 
``core'' of material, within the circumference of the bit, from its 
surroundings, leaving the core generally intact as it is removed from 
the hole (Document ID 3501, p. 6). The cylindrical bit can range in 
size; for example NIOSH described a coring operation used to produce 
holes 2 to 31 inches in diameter in large sections of concrete conduit 
(Document ID 0898, p. 6).
    For rig-mounted core drills, there is one specified control that 
consists of using a tool equipped with an integrated water delivery 
system that supplies water to the cutting surface, operated and 
maintained in accordance with manufacturer's instructions to minimize 
dust emissions. Based on evidence in the record, OSHA has determined 
that baseline conditions for core cutting involve using wet methods and 
that most core cutting machines are provided with and intended to be 
used with a water feed system (e.g., Document ID 0675, p. 1097; 0679, 
pp. 18-21; 0898, p. 6; 3580, Tr. 1415, 1435; 3581, Tr. 1584; 3585, Tr. 
2902). Like other saws included in Table 1, these existing systems will 
fulfill the requirements of Table 1.
    Comments submitted by SMI expressed confusion as to whether or not 
core drilling was included on the table under the entry for drills and 
the appropriateness of using LEV as required under the proposed table 
during core cutting (Document ID 2316, p. 2). In the proposed rule, 
OSHA specifically excluded core cutters from hole drillers using 
handheld drills (see PEA, p. IV-403). OSHA did not include this 
information because OSHA lacked specific information on exposures to 
silica that result from core drilling or from industry's practice of 
using water during coring operations. Upon OSHA's review of core 
cutter/driller operator exposures and hearing testimony from industry, 
OSHA determined that there is the potential for silica exposure when 
employing core saws and that these saws are different enough from other 
drills and cutting tools to warrant the inclusion of its own separate 
entry on Table 1.
    Kellie Vasquez of Holes Incorporated testified that the process of 
core drilling is much different than other types of drilling due to the 
different drill bits used, resulting in much less silica exposure 
(Document ID 3580, Tr. 1484). This is supported by OSHA's review of 
record data on core cutting/drilling, which shows that operators 
generally experience little or no silica exposure during this low-speed 
process, which is already performed using water-fed equipment as a 
standard practice (Document ID 0675, pp. 1097-1098; 0898, p. 15).
    Additional exposure data compiled by CSDA from member jobsites 
(Document ID 3497) and other studies (Document ID 0675; 0679; 0898) 
show that using a

[[Page 16735]]

core drill with wet methods results in exposure levels of less than 50 
[mu]g/m\3\ (Document ID 3497). During hearing testimony, BCTD commented 
that core drills are always used with wet methods (Document ID 3581, 
Tr. 1584). This was supported by Kellie Vasquez of Holes Incorporated 
who stated that her concrete cutting operations employ water 100 
percent of the time (Document ID 3580, Tr. 1483). Accordingly, OSHA 
added dust control specifications for core sawing and drilling to Table 
1 of the final standard for construction. Because the available 
evidence described above demonstrates that using wet dust suppression 
systems for core cutting does not result in silica exposures exceeding 
50 [mu]g/m\3\, the final standard for construction does not require the 
use of respiratory protection.
    Handheld and stand-mounted drills (including impact and rotary 
hammer drills). Handheld drills are used to, among other tasks, create 
holes for attachments and small openings in concrete and other silica 
containing materials (see Section 5.4 of Chapter IV of the FEA). These 
drills can: (1) Be electric, pneumatic, or gas-powered; (2) use rotary 
hammers or percussion hammers; and (3) be free-standing or stand-
mounted. Handheld drills consist of a handle with a trigger button to 
begin drilling, a motor compartment above and perpendicular to the 
handle, and a socket to insert drill bits of varying lengths and styles 
at the end of the motor compartment. Impact and rotary hammer drills 
appear the same, but provide the ability to drill with extra motor-
generated impacts and/or torque. The drills may have a second handle in 
front of the main handle for a worker to grasp with the off hand. To 
control dust, they may contain attachable dust collection systems where 
the end of the drill bit is surrounded by a vacuuming compartment which 
connects to the rest of the drill, allowing for dust to be removed 
while drilling (Document ID 4073, Attachment 4a, Row 68). Handheld 
drills can also be stand-mounted, in which case a drill is turned on 
its side and mounted to an adjustable stand, allowing the worker to 
drill directly into a work product with precision (Document ID 4073, 
Attachment 4a, Row 72).
    Paragraph (c)(1)(vii) of the standard for construction requires 
that handheld and stand-mounted drills be equipped with a commercially 
available shroud or cowling with dust collection system that provides 
at least the minimum air flow recommended by the manufacturer. The dust 
collection system must include a filter cleaning mechanism and be 
equipped with a filter with 99 percent or greater efficiency. The dust 
collection system must be operated in accordance with the 
manufacturer's instructions to minimize dust emissions. In addition, 
OSHA is requiring that a HEPA-filtered vacuum be used when cleaning 
debris from drill holes.
    The proposed Table 1 labeled this category of tools ``Using rotary 
hammers or drills (except overhead).'' In response to several comments, 
OSHA has revised this description to make clear that drills mounted on 
stands are also included and also removed the exclusion for overhead 
drilling. For example, SMACNA recommended expanding the entry for 
rotary hammers and drills to include overhead drilling, contending that 
overhead drilling would be just a safe as other drilling if done as 
directed on the table (Document ID 2226, p. 2). The Mechanical 
Contractors Association of America commented that overhead drilling 
should be included in Table 1 since overhead drilling is a common 
operation in several trades (Document ID 2143, p. 2). OSHA received 
testimony that overhead drilling along with a drill stand with a vacuum 
attachment addresses both ergonomic and silica exposure hazards. After 
review of the evidence in the record, OSHA has determined that it is 
appropriate to remove the exclusion for overhead drilling in the Table 
1 entry for handheld and stand-mounted drills.
    As proposed, Table 1 had separate entries for ``Rotary Hammers or 
Drills'' and ``Jackhammers and Other Impact Drillers.'' OSHA received 
comments from PTI suggesting that impact drills be covered by the entry 
for ``Rotary Hammers or Drills,'' rather than by the ``Jackhammers and 
Other Impact Tools'' entry (Document ID 1973, Attachment 1, p. 4). 
NIOSH also commented on the potential for confusion, noting that a 
rotary hammer or drill is technically an impact driller (Document ID 
2177, Attachment B, pp. 32-33). Therefore, the entry for handheld or 
stand-mounted drills in final Table 1 covers activities related to the 
use of impact and rotary hammer drills. Chipping and breaking 
activities, which are associated with more intense silica exposures, 
are covered by the entry for jackhammers and handheld power chipping 
tools.
    CISC commented that OSHA did not state in the proposed rule that 
the dust collection system needs to be ``commercially available'' 
(Document ID 2320, p. 112). In the final standard for construction, 
OSHA has clarified that Table 1 requires that the handheld or stand-
mounted drill be equipped with a commercially available shroud or 
cowling with dust collection system. Several drilling equipment 
manufacturers sell dust extractors or dust collectors to minimize dust 
escaping into the work area. These systems include a vacuum with a 
filter cleaning mechanism and a filter with 99 percent or greater 
efficiency. Some examples include Bosch, DeWalt, Hilti, and Metabo 
(Document ID 3998, Attachment 10; 4073, Attachment 4a, Rows 15-18, 64-
70, 111-119, 189-195, 289-301, 352-357). OSHA has determined that it is 
feasible for employers to obtain controls for handheld and stand-
mounted drills that meet the specifications in Table 1.
    Based on evidence in the record, OSHA finds that, for most tools, a 
commercial dust control system using an appropriate vacuum will provide 
the most reliable dust capture. Average respirable quartz levels varied 
among the different cowling/vacuum combinations. In one study, all 
commercial cowl/vacuum combinations tested resulted in personal 
breathing zone exposures of 28 [mu]g/m\3\ or less during drilling 
(Document ID 1142, p. 42). Another study reported median silica 
exposures of 60 [mu]g/m\3\ and 45 [mu]g/m\3\, depending on drill bit 
size, in a room with limited air exchange (Document ID 1391, pp. 11-12, 
15-19). These findings indicate that providing a means of exhaust when 
working indoors or in enclosed areas, as required under paragraph 
(c)(2)(i) of the standard for construction, in addition to using dust 
collection systems, will maintain exposures below 50 [mu]g/m\3\. Based 
on these findings, OSHA is not requiring the use of respiratory 
protection when using handheld or stand-mounted drills, including 
overhead drilling, for any task duration.
    The practice of dry sweeping or brushing debris from a hole, or 
using compressed air to clean holes, contributes to the exposure of 
employees using drills. Based on the evidence in the record, OSHA is 
requiring that holes be cleaned with a HEPA-filtered vacuum. Any method 
for cleaning holes can be used, including the use of compressed air, if 
a HEPA-filtered vacuum is used to capture the dust. If a HEPA-filtered 
vacuum is not used when cleaning holes, then the employer must assess 
and limit the exposure of that employee in accordance with paragraph 
(d) of the standard for construction.
    While the paragraph on housekeeping (paragraph (f) of the standard 
for construction) also applies when employers are following paragraph 
(c) of the standard for construction, the employer must ensure that all 
of the engineering controls and work practices specified on Table 1 are 
implemented.

[[Page 16736]]

For example, paragraph (f)(2)(i) of the standard for construction 
permits the use of compressed air when used in conjunction with a 
ventilation system that effectively captures the dust cloud. However, 
to fully and properly implement the controls on Table 1, an employer 
using compressed air when cleaning holes during tasks using handheld or 
stand-mounted drills or dowel drilling rigs for concrete must use a 
HEPA-filtered vacuum to capture the dust, as specified in paragraphs 
(c)(1)(vii) and (viii) of the standard for construction, not just a 
ventilation system as specified in paragraph (f)(2)(i) of the standard 
for construction.
    PCI noted that anchor holes must be blown clean to obtain adequate 
adhesion, and recommended that the use of compressed air and dry 
sweeping be allowed unless exposures will exceed 50 [mu]g/m\3\ 
(Document ID 2276, pp. 10-11). This recommendation assumes exposure 
assessment, however, the construction standard does not require such 
assessment where the task is included in Table 1 and the employer is 
following Table 1. Although OSHA is allowing the use of compressed air 
if used in conjunction with a HEPA-filtered vacuum to capture the dust, 
OSHA has determined that there are a number of feasible alternatives to 
using compressed air. At least one tool manufacturer offers an anchor 
system with ``no hole cleaning requirement whatsoever,'' due to the use 
of a drill with a ventilated drill bit (Document ID 4073, Attachment 
4b, Slide 12). Another manufacturer offers a ``hole cleaning kit'' for 
large hammer hole drilling, which consists of a doughnut-shaped dust 
collection head that attaches directly to a vacuum cleaner hose. The 
head is placed against the surface to be drilled and captures dust 
generated as the hole is drilled (Document ID 4073, Attachment 4b, 
Slide 17). This hole cleaning kit also includes two sizes of hole 
cleaning tubes. Such a control could be used with existing as well as 
new drills (e.g., Document ID 3998, Attachment 10, p. 42).
    Data suggest that decreasing employees' reliance on blowing or dry 
sweeping drilling debris can reduce exposures by approximately 50 
percent (e.g., Document ID 1391, pp. 32-33). This 50 percent reduction 
would bring exposure levels to 50 [mu]g/m\3\ or below for all the drill 
operators who are currently exposed to silica at levels between 50 
[mu]g/m\3\ and 100 [mu]g/m\3\. Thus, OSHA has determined that a HEPA-
filtered vacuum must be used when cleaning holes in order to reduce 
silica exposure.
    Dowel drilling rigs for concrete. Paragraph (c)(1)(viii) of the 
standard for construction covers dowel drills (i.e., gang drills), 
which are drills with one or more drill heads used to drill holes in 
concrete for the placement of steel supports (see Section 5.9 of 
Chapter IV of the FEA). When operating dowel drills, Table 1 requires 
that the rig be equipped with a shroud around the drill bit and a dust 
collection system that has a filter with 99 percent or greater 
efficiency. In addition, Table 1 requires that dust collection 
equipment be equipped with a filter cleaning mechanism.
    NIOSH found that employees using compressed air to clean the filter 
after dowel drilling resulted in some of the highest measured exposure 
to respirable dust during the task, and could cause damage to the 
filter (Document ID 4154, p. 26). NIOSH also pointed out that the 
reverse pulse feature on the dust collector should preclude the need to 
remove filters for cleaning (Document ID 4154, p. 26). OSHA agrees and 
has included the specification for a filter cleaning mechanism for 
dowel drills in Table 1. Finally, Table 1 requires that a HEPA-filtered 
vacuum is used when cleaning holes. OSHA recognizes that it may be 
necessary at times for employers to use compressed air to clean holes, 
and thus, as with handheld and stand-mounted drills, Table 1 does not 
preclude its use when cleaning the debris from holes caused by dowel 
drilling, so long as a HEPA-filtered vacuum is employed at the same 
time to effectively capture the dust.
    In the proposed rule, OSHA included dowel drills within the entry 
titled ``Operating Vehicle-Mounted Drilling Rigs for Concrete.'' 
However, OSHA has determined that the exposures that result from dowel 
drilling rigs equipped with LEV systems are substantially higher than 
is the case for vehicle-mounted concrete drilling rigs. Therefore, 
respirator requirements are different for the two kinds of equipment 
(see Sections 5.4 and 5.9 of Chapter IV of the FEA).
    Exposure information on concrete dowel drilling in the record is 
limited but shows that, even with LEV, exposures are likely to exceed 
50 [mu]g/m\3\. Exposure studies by NIOSH on concrete dowel drills, 
manufactured by both EZ Drill and Minnich Manufacturing, that were 
equipped with close capture hoods and a dust collection system showed 
that workers were often still exposed to respirable silica dust levels 
well above 50 [mu]g/m\3\, with 8-hour TWA exposures to respirable 
quartz ranging from 24 to 420 [mu]g/m\3\ with a geometric mean of 130 
[mu]g/m\3\ (Document ID 4154, p. 25). NIOSH found that using an air 
lance and compressed air to clean holes and to clean the filter and 
hoses of the dust collector contributed to these high exposures, and 
NIOSH recommended the use of a pneumatic vacuum to clean holes and 
components of the dust collector (Document ID 4154, p. 26). The record 
contains no information on exposures that result when vacuums are used 
to clean holes. As stated previously, exposures that result from dowel 
drilling rigs equipped with LEV systems are substantially higher than 
is the case for vehicle-mounted concrete drilling rigs. Based on this 
information, OSHA has modified the respirator requirement for dowel 
drilling, and is requiring the use of respiratory protection with a 
minimum APF of 10 regardless of task duration.
    Comments on OSHA's proposed requirements for dowel drilling were 
limited. Holes Incorporated, Atlantic Concrete Cutting and CISC all 
stated that outdoor concrete dowel drilling should be included on Table 
1 (Document ID 2338, p. 3; 2320, p. 14; 2367, p. 4). Atlantic Concrete 
Cutting further suggested that the appropriate control for dowel 
drilling is to limit this task to outdoors only and ``provide 
sufficient ventilation'' (Document ID 2367, p. 4). As suggested, OSHA 
has included a separate entry for concrete dowel drilling on Table 1, 
but with more detailed control requirements than suggested by Atlantic 
Concrete Cutting based on information contained in the record. OSHA 
agrees with Atlantic Concrete Cutting that the entry on Table 1 should 
be limited to outdoor operations since there is no information in the 
record as to the appropriate level of respiratory protection needed 
when operating dowel drills in enclosed areas, and has accordingly 
revised Table 1 of the final rule to so indicate.
    PCI commented that anchor holes must be blown clean using 
compressed air to obtain adequate adhesion (Document ID 2276, p. 10). 
In its feasibility analysis, OSHA identified this task as a significant 
source of exposure to respirable crystalline silica. Therefore, for the 
reasons previously stated, Table 1 also includes a requirement to use a 
HEPA-filtered vacuum when cleaning holes, with or without the use of 
compressed air, in connection with this task.
    Vehicle-mounted drilling rigs for rock and concrete. Paragraph 
(c)(1)(ix) of the standard for construction requires that vehicle-
mounted rock and concrete drilling rigs be equipped with a dust 
collection system with a close capture hood or shroud around the drill 
bit with a low-flow water spray to wet the dust discharged from the 
dust collector, or be operated from within an enclosed cab in

[[Page 16737]]

conjunction with water applied at the drill bit for dust suppression 
(see Section 5.9 of Chapter IV of the FEA). The specifications of 
paragraph (c)(2)(iii) of the standard for construction apply to the 
cabs.
    The proposed rule had separate entries for vehicle-mounted drilling 
rigs for rock and vehicle-mounted drilling rigs for concrete, both of 
which specified a combination of LEV and water use. OSHA has determined 
that, since the rigs and the approach to dust control are similar for 
both, they can be combined in Table 1 of the final standard for 
construction. OSHA has also determined that it is appropriate to allow 
employers the option of having the drill operator work within an 
enclosed cab meeting the requirements of paragraph (c)(2)(iii) of the 
standard for construction and to apply water at the drill bit to ensure 
that the operator and other employees assisting are protected when 
working near the drill bit.
    Workers using vehicle-mounted drilling rigs position and operate 
the drill rigs from control panels mounted on the rigs. These workers 
may also perform intermittent tasks near the drilling point such as 
fine-tuning the bit position, moving debris away from the drill hole, 
and working directly or indirectly with compressed air to blow debris 
from deep within the holes. Workers using drilling rigs can be exposed 
to dust generated by the action of the drill bit and from dust raised 
by air movement or a compressed air nozzle. Although rig-based drilling 
is often a one-person job, some of the associated activities, such as 
fine-tuning the drill position and clearing debris from in or around 
the holes, can be performed by a second worker (Document ID 0908, p. 1; 
1563, p. 3).
    In the proposed rule, OSHA specified requirements for the dust 
collections systems regarding smooth ducts, transport velocities, 
clean-out points, pressure gauges, and activation of the LEV. These 
requirements came from a NIOSH evaluation of control technology for 
dowel-pin drilling (Document ID 1628). The final rule does not require 
these specific control parameters for vehicle-mounted drilling rigs for 
rock and concrete. OSHA has determined that dust controls for dowel 
drilling rigs are substantially different than vehicle-mounted rock and 
concrete drilling rigs; they are addressed separately in the previous 
section. Dust collection systems that use a hood or shroud around the 
drill bit have been proven effective in reducing exposures to 
respirable crystalline silica. NIOSH found that, when used properly, 
modern shroud designs now help achieve dust control objectives more 
consistently for rock drilling rigs than in the past (Document ID 0967, 
pp. 5-9). Based on information contained in the record, OSHA finds that 
dust collectors and shrouds are commercially available (Document ID 
0669; 0813).
    Although the LEV system will control dust emissions at the drill 
bit, there are still dust emissions at the dust collector discharge 
area, which can contribute to either the operator's or other employees' 
exposures. Organiscak and Page (1995) found that enclosing the dust 
collector discharge area with a shroud can reduce respirable dust 
levels by 80 percent (Document ID 3613, p. 11). However, evidence in 
the record shows that the combination of LEV at the drill bit and water 
application will be more effective in that water can be used to control 
dust emission points where drilled material is discharged. Organiscak 
and Page (1995) illustrated the effectiveness of combined wet methods 
and dust collectors in their U.S. Bureau of Mines study, which compared 
rock drilling using LEV with and without the addition of water for dust 
suppression. The addition of wet methods to the LEV system showed a 92 
percent reduction in respirable dust and eliminated nearly all of the 
visible dust. Quartz results decreased from 143 [mu]g/m\3\ when the 
water was off (LEV alone) to 9 [mu]g/m\3\ when water was added. OSHA 
obtained sample results of 54 [mu]g/m\3\ and 35 [mu]g/m\3\ during an 
inspection for two workers drilling in granite that contained 30-40 
percent crystalline silica (Document ID 0034, pp. 8, 23-26, 35-38). 
Both drillers were reportedly using water and LEV, although specific 
details about the configuration of the controls were not discussed 
(Document ID 0034, pp. 23, 89-93). A third sample that was below the 
limit of detection for crystalline silica was collected on the same 
site for a laborer who helped with positioning the drills (Document ID 
0034, pp. 39-42).
    OSHA received many comments related to the proposed requirements 
for rock and concrete drillers. CISC noted that it is more common to 
use wet methods when operating vehicle-mounted drilling rigs for rocks 
as opposed to using dust collection systems (Document ID 2319, pp. 108-
109). A number of other commenters noted the prevalence of wet methods 
use in the industry (e.g., Document ID 1983, pp. 1-2; 2116, Attachment 
1, p. 33; 3496, p. 6). For instance, CSDA commented that nearly 100 
percent of CSDA contractors use water on every job in order to prolong 
the life of the diamond blade (Document ID 3496, p. 6). The National 
Ground Water Association (NGWA) noted that it is industry practice when 
drilling water wells to use foam as a wet control method:

    Industry practice is to use the engineering control of soap 
injection where water is mixed with foam. The foam mixtures of water 
and foam products are effective in mitigating the hazard of dust 
when properly used as they can carry particles ranging from .03 mm 
to the size of a quarter. There are multiple manufacturers of the 
foam products and these products have been approved for use when 
drilling sanitary water wells. The foam agents are NSF approved and 
have also been approved for use in many states (Document ID 1983, 
pp. 1-2).

    NGWA also explained that all rotary drilling machines have been 
equipped with some type of water injection system since the early 1970s 
(Document ID 1983, p. 2).
    Historically, construction and mining investigators have reported 
dust control efficiencies of 96 to 98 percent through the routine use 
of wet dust suppression methods, depending on the methods used; 
however, the water flow necessary for dust control can create problems 
under certain working conditions (e.g., moisture shortening the life of 
certain drill bits (such as tricone roller bits), high-pressure water 
causing spalling of the drill hole wall) (Document ID 0967, p. 6). 
Advances in recent decades have produced equipment that permits workers 
to use wet methods in a wider range of circumstances. New ``water 
separator sub'' designs extend bit life beyond the previous norm and 
reduce spalling in a variety of rock types (Document ID 0967, p. 6). 
Several commenters stated that wet methods are used frequently and are 
effective in controlling dust (Document ID 1983, pp. 1-2; 3580, Tr. 
1435; 3496, p. 6).
    OSHA's exposure profile contains five sample results for workers 
using wet methods with no other controls while drilling. These five 
samples have a mean of 24 [mu]g/m\3\ and a median of 17 [mu]g/m\3\, 
with a high exposure of 57 [mu]g/m\3\ and two results below the LOD 
(Document ID 0034; 0226). A review of studies by NIOSH (2008) evaluated 
the use of wet methods in different types of drilling, including roof 
bolting (rock bolting) and surface rock drilling (Document ID 0967). 
NIOSH found that for roof bolting, silica dust was best controlled at 
its source through dust collection or wet drilling, similar to the 
standard practice in metal mines of using pneumatic percussion drills 
with water in addition to compressed air to flush the drill cuttings 
from the hole. This drilling method was found to be the best method of 
dust control, with

[[Page 16738]]

dust reductions ranging from 86 percent to 97 percent (Document ID 
0967, pp. 2, 4). The high dust reductions from wet drilling were 
confirmed in later studies that evaluated the use of water mists and 
foams injected through the drill steel and found that those controls 
reduced dust concentrations by 91 percent and 96 percent, respectively 
(Document ID 0967, p. 2). NIOSH also found that for surface drilling, 
wet drilling techniques provided the best dust control. Wet drilling 
provided dust control efficiencies of up to 97 percent at a water flow 
rate of 4.5 L/min (1.2 gallons per minute) (Document ID 0967, p. 6). 
OSHA thus finds that water directed at the material discharge point is 
an effective dust suppressant in vehicle-mounted rock and concrete 
drilling and specifies its use on Table 1 for this task.
    OSHA also finds that the use of an enclosed cab can effectively 
reduce exposures for vehicle-mounted drill operators. Enclosed cabs, 
however, only benefit the operator when the operator remains in the 
cab, and they do not control employee exposure during positioning or 
hole-tending activities. Therefore additional controls are necessary to 
protect employees from exposure to silica dust when performing 
activities outside of the cab. As described above, OSHA has determined 
that the use of water for dust suppression on the drill bit will 
effectively reduce exposures in situations where employees must also 
perform activities outside the cab.
    Based on the information discussed above, Table 1 of this standard 
provides the option for employees to operate a vehicle-mounted rock or 
concrete drill from within an enclosed cab in conjunction with water 
applied at the drill bit for dust suppression; wherever cabs are 
specified in Table 1, however, the cabs must meet the requirements of 
paragraph (c)(2)(iii) of the standard for construction, as discussed 
above. OSHA has determined that the enclosed cab will adequately 
protect the operator while the addition of water at the drill bit will 
reduce exposures for employees in the area. The alternative control 
option included in Table 1, a dust collection system and water sprays 
at the discharge point (where the system ultimately dumps extracted 
dust), has also been proven to reduce exposures for both the operator 
at the drill controls and those employees in the vicinity. When the 
specified dust control methods are fully and properly implemented, TWA 
exposure levels are expected to remain below 50 [mu]g/m\3\, and 
therefore, Table 1 does not require use of respiratory protection 
regardless of task duration for either control option. In the proposed 
rule, OSHA required the use of respiratory protection when the task 
lasted more than four hours. However, this was due to the inclusion of 
dowel drilling rigs within the entry for ``Operating Vehicle-Mounted 
Drilling Rigs for Concrete.'' As explained above, OSHA has determined 
that the exposures that result from dowel drilling rigs equipped with 
LEV systems, for which respirators are required regardless of task 
duration, are substantially higher than is the case for vehicle-mounted 
concrete drilling rigs.
    IUOE commented that Table 1 would be clearer if it specified that 
employers who use open cabs during concrete drilling are not exempt 
from exposure assessment when employers implement the other controls 
listed for vehicle-mounted drilling rigs for concrete (Document ID 
2262, Attachment 1, p. 48). OSHA considers the rule to be clear as 
written: If an employer chooses to operate vehicle-mounted drilling 
rigs for rock and concrete from within an enclosed cab, it must follow 
the requirements in paragraph (c)(2)(iii) of the standard for 
construction and apply water for dust suppression at the drill bit. 
Otherwise, the employer must follow the alternative shrouded dust-
collection-system compliance method in Table 1 or the requirements in 
paragraph (d) of the standard for construction, which allow for 
alternate exposure control methods provided that employee exposures are 
assessed and exposures are kept at or below the PEL. Additionally, IUOE 
suggested that OSHA explicitly state on Table 1 that the employer does 
not have the option of respirator use as a means to control exposures 
during rock crushing or rock and concrete drilling if the employer 
chooses not to use enclosed cabs as an engineering control (Document ID 
2262, Attachment 1, p. 48). OSHA notes that Table 1 of this final 
standard does not require that drilling rig operators work from 
enclosed cabs exclusively. Because employers can choose between the two 
control methods listed on Table 1, employees that use open cabs during 
drilling activities would not be required to conduct exposure 
assessments if they are using a dust collection system with a close 
capture hood or shroud around the drill bit and are ensuring that the 
material at the dust collector discharge point is being wetted. If that 
method is followed, OSHA, having found based on the exposure profile 
and record evidence that exposures will consistently be at or below the 
PEL, has not included a respirator requirement on Table 1; where 
respirators are not required to satisfy compliance obligations (as is 
the case here if Table 1 is fully and properly implemented), OSHA does 
not expect employers to require the use of respirators anyway. However 
employers that do not follow either control strategy specified in Table 
1 must comply with paragraph (d) of the standard for construction, 
which could require respirator use if exposures are measured at or 
above the PEL when using feasible engineering and work practice 
controls.
    IME stated that the final rule should allow for the use of 
equivalent, alternative control methods (Document 2213, Attachment 1, 
p. 2). Table 1 is intended to represent the most reliable control 
methods available for reducing exposures, based on the evidence 
contained in the record. Employers who wish to implement an alternative 
control method can do so, but those employers must comply with 
paragraph (d) of the standard for construction.
    IUOE, among others, urged OSHA to explore additional options for 
exposure controls to protect operators working outside the cab when 
drilling. Both IUOE and Fann Contracting asserted that Table 1 does not 
address protection of operators who perform construction activities 
outside the cab with or without remote controls (Document ID 2262, 
Attachment 1, p. 45; 2116, Attachment 1, p. 5). In response, Table 1 of 
the final standard now includes a requirement to use water for dust 
suppression at the drill bit when the drill is being operated from an 
enclosed cab to minimize the exposure to other employees outside the 
cab.
    OSHA's proposed Table 1 entry for rock drilling would have required 
that employees use respirators when working under the shroud. OSHA 
proposed this requirement based on a determination that employees' 
exposures would be high given their proximity to the point of dust 
generation. IME suggested that respirators should not be required at 
all times because there are circumstances where the time spent working 
under the shroud is extremely brief or infrequent and potential 
exposures will be minimal or negligible (Document ID 2213, p. 2). NUCA 
commented that this requirement creates hazards for employees working 
under the shroud (Document ID 2171, p. 10). In response to these 
comments and after reviewing the record, OSHA has not retained this 
respirator requirement in the final standard. The Agency finds that the 
record contains substantial evidence that when the dust controls 
required by Table 1 are fully and properly implemented, TWA exposures 
to silica are unlikely to exceed 50 [mu]g/m\3\

[[Page 16739]]

(see Section 5.9 of Chapter IV of the FEA). In reviewing dust controls 
historically for drilling operations, NIOSH found that, when used 
properly, modern shroud designs now help achieve dust-control 
objectives more consistently than in the past (Document ID 0967, pp. 5-
9). Furthermore, the record indicates that work under a shroud is 
periodic or intermittent and contains no evidence suggesting that this 
work is likely to result in silica exposures exceeding 50 [mu]g/m\3\ as 
an 8-hour time-weighted average. Accordingly, Table 1, unlike in the 
proposed rule, does not include a respiratory protection requirement 
for rock and concrete drillers on open (or enclosed) vehicle-mounted 
rigs.
    NSSGA recommended that OSHA clarify the requirement for wearing 
respirators while working under the shroud by replacing the term 
``shroud'' with ``engineered fugitive dust control method, e.g., a 
shroud, water spray, etc.'' (Document ID 2327, Attachment 1, p. 21). 
Since the Agency has eliminated the requirement for using respirators 
under the shroud, NSSGA's suggestion is moot.
    Jackhammers and handheld powered chipping tools. Hand-operated 
breaking and chipping power tools and equipment, commonly known as 
jackhammers, pavement breakers, breaker hammers, percussion or chipping 
hammers, and needle guns, are used in construction for fracturing 
materials, which often include silica (e.g., rock, concrete, asphalt, 
or masonry surfaces), by delivering rapid repetitive blows (see Section 
5.5 of Chapter IV of the FEA). The hammers typically consist of a large 
compartment containing a motor, two attached handles to grip the tool, 
and a large socket out of which the drill or hammer-like metal 
breaking/chipping implement extends. A worker typically will aim the 
metal drill/hammer at a target surface while standing one to five feet 
away either directly overhead or at an angle, and press the point of 
contact into the surface to break, fracture, or chip away at it 
(Document ID 4073, Attachment 4a, Row 199).
    In the proposed standard, this entry was titled ``Using Jackhammers 
and Other Impact Drillers.'' OSHA had a separate entry for ``Rotary 
Hammers or Drills.'' NIOSH commented on the potential for confusion 
with these titles, noting that a rotary hammer or drill is technically 
an impact driller (Document ID 2177, Attachment B, pp. 32-33). OSHA has 
revised the headings for the relevant Table 1 entries ((c)(1)(vii) and 
(x)). The revised heading for paragraph (c)(1)(x) removes the term 
``other impact drillers'' and replaces it with ``handheld powered 
chipping tools.'' This change was made to clarify that this entry 
applies only to handheld tools that use an impact movement to chip or 
fracture the material being worked on. The heading for (c)(1)(vii) was 
revised from ``Using Rotary Hammers of Drills'' to ``Handheld and 
Stand-Mounted Drills (Including Impact and Rotary Hammer Drills)'' in 
order to clarify that all handheld drills, including impact drilling, 
are covered under that entry.
    When using jackhammers and other handheld powered chipping tools at 
construction sites to fracture silica-containing material, paragraph 
(c)(1)(x) of the standard for construction requires the employer to 
operate the tools using either a water delivery system that supplies a 
continuous stream or spray of water at the point of impact, or a tool 
equipped with a commercially available shroud and dust collection 
system operated and maintained in accordance with manufacturer's 
instructions to minimize dust emissions. If the employer is operating a 
tool with the shroud and dust collection system, Table 1 requires that 
the dust collector (i.e., LEV) must provide at least the air flow 
recommended by the tool manufacturer, and have a filter with 99 percent 
or greater efficiency and a filter cleaning mechanism. These specified 
controls are essentially the same as those that were proposed, but the 
final standard makes clear that if a shroud and dust collector are 
used, it must be commercially available equipment. Unlike the use of a 
shrouded dust collection system, a water delivery system is not 
required to be commercially available but can be assembled and 
installed by the employer.
    OSHA revised the respirator use requirements from the proposed rule 
by distinguishing between indoor and outdoor environments. Table 1 of 
the final standard for construction does not require respiratory 
protection if tools are used outdoors for four hours or less per shift. 
OSHA based this revision on record evidence showing that exposures can 
be maintained at or below 50 [mu]g/m\3\ using either water sprays or 
LEV, provided work does not exceed the median task duration (231 
minutes) reported by Flanagan et al. (Document ID 0677, p. 147; 0677, 
Attachment 2) (see Section 5.5 of Chapter IV of the FEA). If tools are 
used outdoors for more than four hours per shift, Table 1 requires the 
use of respiratory protection having a minimum APF of 10 to ensure that 
employees are protected from exposures above 50 [micro]g/m\3\. If the 
tools are used indoors or in an enclosed area, Table 1 requires the use 
of respiratory protection having a minimum APF of 10 to ensure that 
employees are protected from exposures above 50 [micro]g/m\3\, 
regardless of the amount of time the tools are operated during the work 
shift.
    NUCA testified during the hearing that jackhammering is one of the 
construction activities most likely to expose employees to silica 
(Document ID 3583, Tr. 2255). OSHA's exposure profile for this task 
confirms this (Table IV.5.5-B in Section 5.5 of Chapter IV of the FEA); 
73 of 98 TWA sample results (74 percent) were above 50 [micro]g/m\3\ 
for workers using jackhammers and handheld power chipping tools 
operated without controls. For tools operated with water, 12 of 16 TWA 
sample results (75 percent) exceeded 50 [micro]g/m\3\, but information 
on how the water was applied and whether it was sufficient was lacking. 
Various studies have demonstrated that properly used wet methods can 
substantially reduce respirable silica levels by 90 percent and higher 
(Document ID 0865, p. iv; 0867, p. 3; 0838, p. 1; 0914; 1267, pp. 493-
494; 2177, Attachment D, p. 19). NIOSH studies that examined water 
spray devices designed to optimize dust suppression (directed mist or 
solid cone nozzle) have found that dust and/or silica exposures are 
reduced by 72 to 90 percent at a flow rate of approximately 350 
milliliters per minute (ml/min) (Document ID 0865; 0867; 1267, pp. 493-
494). Although not commercially available at this time, the record 
shows a number of examples of water suppression systems that have been 
developed and tested and are ready for commercial introduction or can 
be easily assembled from readily available hardware materials and 
instructions from the New Jersey Laborers' Health and Safety Fund 
(Document ID 0741; 0838; 0914; 2177, Attachment D, pp. 4-7; 3732, 
Attachment 3, p. 10).
    The shroud and LEV control for jackhammers and handheld powered 
chipping tools was found to be less effective than water suppression 
but still reduced exposures up to 69 percent (Document ID 1267, pp. 
493-494; 0865, p. iv; 0651, p. 1; 0667, pp. 1-3; 0862, pp.10-11, 14). 
Also, the respirable silica levels generated by these tools are 
dependent on whether they are being operated outdoors, indoors, or in 
an enclosed area. Several powered impact tool manufacturers currently 
offer LEV options (e.g., Document ID 1288 p. 2; 1700, p. 1). Other 
companies specialize in manufacturing after-market shrouds or exhaust 
ventilation systems for various handheld tools such as jackhammers and 
chipping equipment

[[Page 16740]]

(Document ID 0566, p. 1; 1264, pp. 4-9; 1266, pp. 9-28; 1671; 1366; 
1399; 3806, pp. 272-273, 276).
    OSHA received a number of comments on the jackhammer and handheld 
powered chipping tool entries on Table 1. CISC commented that OSHA did 
not indicate in the proposed Table 1 that the dust collection system 
needed to be commercially available and did not set parameters for the 
functioning of the dust collection system (Document ID 2319, p. 107). 
Based on comments and testimony in the record, OSHA has clarified the 
entry in Table 1 for jackhammers and handheld powered chipping tools to 
read ``use tool equipped with commercially available shroud and dust 
collection system.'' OSHA has added to Table 1 the following 
requirements: Operate and maintain the tool in accordance with the 
manufacturer's instructions to minimize dust emissions; provide at 
least the air flow recommended by the tool manufacturer; and use a 
filter with a 99 percent or greater efficiency and a filter cleaning 
mechanism.
    CISC also expressed concern that using wet methods may raise 
quality issues, for example by introducing water to the base when 
pouring new concrete (Document ID 2319, p. 107). The water delivery 
system required by Table 1 must deliver a continuous stream or spray of 
water at the point of impact. The water delivery system evaluated by 
NIOSH delivered between 250 and 300 ml of water per minute and the 
authors observed that water applied at these flow rates did not add a 
substantial amount of water to the work surface nor did it result in 
substantial accumulation of water (Document ID 0867, pp. 8, 15). Given 
that a substantial amount of water is not needed, OSHA finds that 
proper implementation of the water delivery system is unlikely to lead 
to quality control issues. Furthermore, other than the hypothetical 
situation raised by CISC, there is no evidence in the record showing 
that using wet methods with jackhammers and powered chipping tools 
results in quality issues. Furthermore, Table 1 of the final standard 
provides two options for dust control of jackhammers and handheld 
powered chipping tools. The employer can use a tool that is equipped 
with a commercially available shroud and dust collection system as an 
alternative to using water.
    Some commenters discussed that water may introduce slip hazards; 
however, comments and hearing testimony described current contractor 
practices that countered these concerns (Document ID 2171 p. 4; 3589, 
Tr. 4295-4296). OSHA understands the concerns about possible slip 
hazards from the use of water; however, NIOSH investigators noted that 
the relatively low water flow rates (300 ml/min) used to suppress dust 
during jackhammering did not result in a substantial accumulation of 
water on work surfaces. OSHA expects that proper implementation of the 
water delivery system will include taking measures to contain any 
runoff to prevent the accumulation of water on walking and working 
surfaces.
    The water delivery systems described in OSHA's feasibility 
assessment chapter on jackhammers, chipping hammers, and other powered 
handheld impact tools (see Section 5.5 of Chapter IV of the FEA), 
include portable water tank systems that can easily be brought to a 
construction site by a pickup truck or trailer, even in a remote area 
(Document ID 0867, p. 4; 0741 p. 1). These water delivery systems can 
be operated by one worker and would not require a second worker to 
supply the water at the point of impact (Document ID 0838, p. 2).
    Handheld grinders for mortar removal (i.e., tuckpointing). Handheld 
grinders are tools fitted with rotating abrasive grinding blades, 
discs, or small drums. Tuckpointers are a subset of grinders who 
specialize in removing deteriorating mortar from between bricks and 
replacing it with fresh mortar (``tuckpointing'') (see Section 5.11 of 
Chapter IV of the FEA). Tuckpointing is most commonly performed for 
exterior wall maintenance and so generally occurs outdoors, but can 
occur indoors where there is interior masonry. The initial phase of 
tuckpointing involves using handheld grinders to grind old mortar from 
between bricks on a section of the wall. A grinder typically has two 
handles that can form various angles with each other and are connected 
to a rotating blade located between them. The worker typically holds 
one handle in each hand, forming an angle allowing the worker to press 
the rotating blade against the mortar between bricks to abrasively 
remove it (Document ID 4073, Attachment 4a, Row 226).
    Paragraph (c)(1)(xi) of the standard for construction requires that 
this task be performed using a grinder equipped with a commercially 
available shroud and dust collection system and operated in accordance 
with manufacturer's instructions. Additionally, the dust collection 
system must be capable of providing at least 25 cfm of air flow per 
inch of wheel diameter and be equipped with a filter that has a 99 
percent or greater efficiency and either a cyclonic pre-separator or a 
filter cleaning mechanism. The proposed requirement was similar but 
specified the air flow to be at least 80 cfm, rather than 25 cfm per 
inch of blade diameter, and also included a number of work practices. 
OSHA revised the controls for this task based on comments received in 
the record, as described below.
    BCTD commented that ``Tuckpointing,'' as the entry was titled in 
proposed Table 1, is an operation that consists of a series of tasks 
(chipping or cutting out old mortar, preparing replacement mortar, 
cleaning the joints, applying fresh mortar, and applying a sealer), 
while the listed control was clearly directed at the task of using a 
``hand-operated tuckpoint grinder'' (Document ID 2371, p. 25). To 
clarify its intent to address the grinding of old mortar, OSHA has re-
named the entry for paragraph (c)(1)(xi) of the standard for 
construction to be ``Handheld grinders for mortar removal (i.e., 
tuckpointing).''
    Recent dust control efforts for tuckpointing have focused on using 
a dust collection hood (also called a shroud) that encloses most of the 
grinding blade and a vacuum cleaner system that is used to suction 
(exhaust) air from these hoods to collect dust and debris. These shroud 
and vacuum combinations generally capture substantial amounts of 
debris. In hearing testimony, Tom Ward, representing BAC, showed a 
video of local exhaust engineering controls for tuckpointing and 
described them as ``extremely effective'' (Document ID 3585, Tr. 3069). 
However, OSHA's exposure profile for tuckpointing shows that, even with 
these controls, silica exposures often exceed 100 [micro]g/m\3\ (25 
percent of results exceed 250 [micro]g/m\3\ when workers use LEV for 
outdoor tuckpointing). An additional survey added to the rulemaking 
record reported results at two tuckpointing sites using vacuum and 
shroud systems. Air samples taken during 201 to 385 minutes of mortar 
grinding showed 8-hour TWA silica exposures ranging from 74 to 1,100 
[micro]g/m\3\ (Document ID 4073, Attachment 9l, p. 4).
    CISC questioned why employers can only use commercially available 
shrouds for hand-operated grinders, eliminating the use of specialty 
manufactured products (Document ID 2319, p. 110). OSHA is unsure of 
what CISC means by ``specialty manufactured products'' and CISC's 
written comments and testimony did not provide further detail. However, 
it is not OSHA's intent to eliminate the use of products that are 
custom made by aftermarket manufacturers (i.e., made by someone other 
than the original tool manufacturer) which are intended to fit the make 
and model of the grinder and

[[Page 16741]]

designed to meet the particular needs and specifications of the 
employer purchasing the product. The ``commercially available'' 
limitation is meant only to eliminate do-it-yourself on-site 
improvisations by the employer. OSHA's technological feasibility 
analysis provides ample evidence that exposures to silica are 
substantially reduced when using commercially available dust controls 
(see Chapter IV of the FEA). To meet the requirements of Table 1, 
however, any specialty manufactured product has to satisfy all the 
requirements for this entry.
    In proposed Table 1, OSHA specified that the dust collection system 
used must provide at least at 80 cfm airflow through the shroud. For 
the final standard, Table 1 requires that dust collectors have an air 
flow of at least 25 cfm per inch of wheel diameter. This change is due 
to OSHA's review of the evidence in the rulemaking record. 
Computational and laboratory studies by Heitbrink and Bennett (2006) 
and Collingwood and Heitbrink (2007) found that an air flow rate of 80 
to 85 cfm (based on a 4- or 4.5-inch wheel) is the minimum needed to 
efficiently capture dust generated by angle grinders used for 
tuckpointing (Document ID 0728, p. 366; 0600, p. 877). ACGIH (2010) 
recommends 25 cfm to 60 cfm per inch of blade diameter (Document ID 
3997, pp. VS-40-01--VS-40-03). For a typical 4-inch tuckpointing blade, 
25 cfm/inch of diameter is equivalent to 100 cfm, higher than the 80 to 
85 cfm used by Heitbrink and Bennett (2006) and Collingwood and 
Heitbrink (2007). Laboratory tests conducted by Heitbrink and Bennett 
indicate that a vacuum and shroud used by tuckpointers during grinding 
can reduce respirable dust emissions by a factor of more than 400 under 
ideal circumstances, but this reduction factor dropped to 10 when 
vacuum air flow was reduced to less than 80 cfm (Document ID 0728, p. 
375). Furthermore, computational modeling showed that even a modest 
decrease in the air flow rate, from 85 cfm to 70 cfm, cuts the shroud's 
ability to capture dust by more than half. As a result, the estimated 
worker exposure level would be twice as high as it would have been if 
the air flow rate had remained constant at 85 cfm.
    A NIOSH field trial on a vacuum that generated an air flow of 111 
cfm for a grinder with a 4-inch blade showed that exposure levels for 
respirable dust were cut in half compared to using a 76 cfm flow rate 
(Document ID 0863, pp. 24-35). Based on the evidence contained in the 
record, OSHA has determined that the ACGIH (2010) recommendations are 
more protective given the variety of blade diameters, and is requiring 
a minimum 25 cfm of airflow per inch of grinding blade diameter instead 
of the 80 cfm minimum airflow (regardless of blade diameter) through 
the shroud.
    To adequately capture debris during the grinding phase of 
tuckpointing, OSHA is requiring that vacuums be equipped with a 
cyclonic pre-separator to collect large debris before the air reaches 
the filters or be equipped with a filter cleaning mechanism. Cyclonic 
pre-separators minimize the accumulation of debris on filters in the 
vacuum, enhancing the ability of the vacuum to maintain the initial air 
flow rate. When testing a vacuum cleaner model equipped with a cyclonic 
pre-separator, Collingwood and Heitbrink found that the collected 
debris caused the average air flow rate to decrease only from 90 cfm to 
77 cfm (Document ID 0600, p. 884). Heitbrink and Santalla-El[iacute]as 
evaluated two different brands of commercially available vacuum 
cleaners (Tiger-Vac and Dustcontrol) incorporating cyclonic pre-
separation. Air flow rates for both of these vacuums were ``largely 
unaffected'' by debris accumulation up to 35 pounds. Debris 
accumulation also had very little effect on the flow rate measured 
before and after the filter was cleaned (Document ID 0731, pp. 377, 
380). Similarly, during the Collingwood and Heitbrink field trials, the 
Dustcontrol vacuum with cyclonic pre-separator did not lose as much air 
flow as the vacuum designed with vacuum cleaner bags (bags are a more 
common pre-separation method but are subject to clogging) (Document ID 
0600, pp. 883-884). OSHA concludes that cyclonic pre-separation is an 
effective technology for helping to maintain air flow and vacuum system 
effectiveness for the duration of tuckpointing tasks by preventing the 
static pressure increase caused by clogging that would otherwise lead 
to a dramatic decrease in air flow and loss of effective dust capture 
at the shroud.
    The accumulation of material and debris on the filter (filter 
caking) during work causes pressure losses that eventually limit air 
flows in even the most powerful vacuums. As debris accumulates, the 
filter becomes caked with collected dust and air flow decreases. Unless 
the filter is properly cleaned following manufacturer's 
recommendations, the air flow declines rapidly. Cooper and Susi used a 
Dustcontrol 2900c vacuum with ICS Dust Director shroud and Bosch 
tuckpointing grinder to evaluate dust control in a field experiment. 
The authors reported that in four hours of continuous grinding up to 
130 pounds of dust was collected, and that flow rates in the vacuum 
dropped from 90 cfm to 80 cfm in as little as 8 minutes. Thus, regular 
stops to conduct the proper reverse air pulse filter cleaning procedure 
were crucial to successful dust control (Document ID 4073, Attachment 
9M, pp. 4-5, 7-9). Therefore OSHA is requiring the use of a filter-
cleaning mechanism when a cyclonic pre-separator, which removes larger 
debris, is not in place. To assist employees in determining when it is 
time to run a filter cleaning cycle, vacuums equipped with a gauge 
indicating filter pressure or equivalent device (e.g., timer to 
periodically pulse the filter) may be useful (Document ID 0731, p. 
885).
    PTI and OEHCS submitted comments emphasizing the importance of 
effective HEPA filtration in protecting employees from silica dust, and 
recommended that Table 1 require that dust collectors used with 
grinders be equipped with HEPA filters (Document ID 1953, pp. 3-4; 
1973, p. 2-3). However, HEPA filters may rapidly clog during mortar 
grinding, leading to static pressure drop and loss of air flow needed 
to capture dust (see discussion about requirements for dust collection 
systems above). Instead, OSHA is requiring filters having at least 99 
percent dust capture efficiency.
    In proposed Table 1, OSHA included a specification that the grinder 
be operated flush against the work surface and that work be performed 
against the natural rotation of the blade (i.e., mortar debris directed 
into the exhaust). A number of commenters discussed the difficulties of 
complying with this specification (Document ID 2183; 2319). Western 
Construction Group commented that it is not possible to always keep the 
grinder flush with the surface because the blade will be spinning at 
its full speed when cutting into the wall and when the blade is 
extracted from the surface, and explained that it would be difficult to 
keep the blade flush when removing vertical mortar joints (Document ID 
2183, p. 2). OSHA acknowledges there are circumstances that do not 
always permit the tool to be operated in this manner, and has therefore 
removed this provision from Table 1. However, it is OSHA's position 
that full and proper implementation of Table 1 controls includes 
keeping the blade flush with the surface whenever possible, in order to 
optimize the effectiveness of local exhaust capture (e.g., Document ID 
0728, p. 376; 0600, p. 876).
    Western Construction Group also commented that it is not always 
possible to operate the grinder against the natural rotation of the 
blade,

[[Page 16742]]

because a wall needs to be ``prepped'' in order to be in sufficient 
condition for mortar to be placed back into the wall (Document ID 2183, 
pp. 2-3). Western Construction Group explained that during final 
preparation, the blade needs to make short passes back and forth to 
clean the joint and prepare it, and that if workers only operated in 
one direction, they would place a significant burden on their shoulders 
and backs by having to make more passes on the wall to clean the joint 
(Document ID 2183, p. 3). Similarly, CISC commented that workers must 
move the grinder back and forth in short, deliberate motions when 
detailing the joint in order to provide the necessary quality finish 
(Document ID 2319, p. 106). OSHA recognizes that the requirement to 
operate against the direction of blade rotation may have an impact on 
job quality and may increase ergonomic stress. While OSHA has removed 
this specification from Table 1, it is OSHA's expectation that full and 
proper implementation of Table 1 controls includes operating against 
the direction of blade rotation, in accordance with the manufacturer's 
instructions, whenever practical.
    CISC commented that a significant portion of tuckpointing takes 
place at elevated locations on scaffolds and expressed concern about 
the control measures listed introducing significant trip and fall 
hazards at elevated locations (Document ID 2319, p. 110). Grinding 
related to tuckpointing does take place on scaffolds, as evidenced by 
one building project evaluated by Cooper et al. where dust collectors 
were used on scaffolds to grind mortar from the exterior walls of a 12-
story building (Document ID 4073, Attachment 9l, p. 1). When mortar 
grinding will take place on scaffolds, the employer's written exposure 
control plan should include procedures to ensure that the dust 
collector is operated in an effective and safe manner.
    In the proposed standard, OSHA required personal air purifying 
respirators (PAPR) with an APF of 25 to be used while tuckpointing, 
regardless of task duration. The proposed requirement was based on high 
exposures results, including a TWA measurement of 6,196 [mu]g/m\3\ for 
an apprentice mortar grinding with LEV (Document ID 0229, p. 12). 
However, it is clear from this NIOSH report that the LEV system was not 
fully and properly implemented in that the grinder blade was operated 
in a back-and-forth manner with frequent insertions, and the hose from 
the tool to the dust collector would frequently kink and fall off. 
Based on data in the record, OSHA expects that a worker engaged in 
mortar grinding for four hours or less per shift can experience TWA 
exposures of less than 500 [micro]g/m\3\, while a worker performing 
this task more than four hours per shift could be exposed up to nearly 
1,000 [micro]g/m\3\ TWA. Among tuckpointers using LEV outdoors, 40 
percent of samples contained in the exposure profile measured exposures 
below 50 [micro]g/m\3\, with a mean exposure of 348 [micro]g/m\3\ (see 
Section 5.11 of Chapter IV of the FEA). Therefore, Table 1 of the final 
standard is requiring the use of respiratory protection with a minimum 
APF of 10 for work lasting four hours or less in a shift, which is 
reduced from the proposed APF of 25. Based on the evidence of 
continuing improvements in the effectiveness of LEV as reported in the 
literature, the exposure information, and the requirement in paragraph 
(c)(2)(i) to provide a means of exhaust as needed to minimize the 
accumulation of visible airborne dust indoors, OSHA concludes that the 
reduction to an APF of 10 is appropriate for tasks of four hours or 
less in duration. For work lasting more than four hours per shift, OSHA 
is maintaining the requirement to use respiratory protection with a 
minimum APF of 25.
    Handheld grinders for uses other than mortar removal. Handheld 
grinders are tools fitted with rotating abrasive grinding blades, 
discs, or small drums used to smooth, roughen, or reshape concrete 
surfaces (including forming recesses or slots) (see Section 5.11 of 
Chapter IV of the FEA). Grinders may also be used to remove thin layers 
of concrete and surface coatings (e.g., performing small-scale spot 
milling, scarifying, scabbling and needle-gunning). A grinder typically 
has two handles that can form various angles with each other and are 
connected to a rotating blade located between them. The worker 
typically holds one handle in each hand, forming an angle allowing the 
worker to press the rotating blade against the work surface and abrade 
the surface and remove the layer of target material (Document ID 4073, 
Attachment 4a, Row 91).
    Paragraph (c)(1)(xii) of the standard for construction specifies 
two control options. The first control option, which applies only when 
grinders are used outdoors, is to use a grinder equipped with an 
integrated water delivery system that continuously feeds water to the 
grinding surface. When employers choose to use wet grinders indoors or 
in an enclosed area, they must comply with the requirements of 
paragraph (d) of the final rule. The second option is to use a dust 
collector equipped with a commercially available shroud and dust 
collection system. The dust collector must provide 25 cfm or greater of 
air flow per inch of wheel diameter and have a filter with a 99 percent 
or greater efficiency and a cyclonic pre-separator or filter-cleaning 
mechanism. OSHA is requiring that the control must be operated and 
maintained in accordance with manufacturer's instructions to minimize 
dust emissions. The second option is identical to the option required 
for handheld grinders used for mortar removal.
    In the proposed standard, OSHA did not specify that the water 
delivery system be integrated with the grinder. However, OSHA has 
determined that systems that are designed and developed in conjunction 
with the tool are more likely to control dust emissions effectively by 
applying water at the appropriate rate and dust emission points based 
on tool configuration. Further, integrated systems will not interfere 
with other tool components or safety devices. These include free-
flowing water systems designed for blade cooling as well as 
manufacturers' systems designed for dust suppression alone. OSHA is not 
specifying a minimum flow rate, but rather anticipates that the water 
flow rates specified by the manufacturer will optimize dust reduction. 
OSHA also recognizes that using makeshift water delivery systems can 
pose hazards. PTI commented that the use of a water feeding system not 
specified by the tool manufacturer could result in serious personal 
injury and electric shock for tools that are electrically operated 
(Document ID 1973, p. 1). Due to the potential hazards from using a 
water delivery system not specified by the manufacturer, and to ensure 
the effectiveness of the system in controlling dust, OSHA has modified 
Table 1 to require use of integrated water systems that are operated 
and maintained according to manufacturer's instructions to minimize 
dust emissions.
    OSHA received a number of comments related to the use of wet 
methods as a control for handheld grinders. SMI and CISC commented on 
the difficulties of using an integrated water system while grinding, 
arguing that there is a lack of options with both safety guards and 
water supply, that grinders equipped with a water delivery system are 
designed to cool the blade rather than control the dust, and that the 
dust mitigation effects of the water are speculative (Document ID 2316, 
p. 2; 2320, p. 10). However, NIOSH reported that ``several 
manufacturers of smaller grinders do offer electric grinders with

[[Page 16743]]

integrated water supply capability'' and included the catalog of such 
suppliers (Document ID 4233, Attachment 1, pp. 7-8; 3998, Attachment 
10). Studies by Linch et al. (2002), Akbar-Khanzadeh (2007, 2010), and 
Simcox et al. (1999) evaluated the use of wet methods during grinding 
(Document ID 0784; 0552; 3609; 1146). Although there were some 
differences in the effectiveness of systems tested by these 
investigators, all of them reduced dust levels substantially compared 
to dry grinding. Therefore the ability of water to control dust when 
grinding is not speculative and has been demonstrated in various 
studies throughout OSHA's technological feasibility analysis contained 
in Chapter IV of the FEA. In short, OSHA concludes that, based on the 
best available evidence, there are commercially available grinders with 
integrated water supply capability, and that wet methods can be an 
effective control for grinding in many circumstances (Document ID 0522, 
p. 778; 1146, pp. 578-579).
    Francisco Trujillo of Miller and Long commented that wet methods 
often present significant slip and fall hazards and that attempting to 
apply wet methods to any non-horizontal surface has proven ineffective 
and often hazardous when using grinders (Document ID 2345, p. 2). 
Similarly, Stuart Sessions, an economist testifying on behalf of CISC, 
noted that it is difficult to use wet methods in winter in locations 
where the water may freeze (Document ID 3580, Tr. 1322). OSHA 
acknowledges that not every control option is practical in every 
situation, and in such situations, Table 1 of the final standard 
permits use of LEV systems to control dust. However, OSHA concludes 
that wet methods represent a feasible and effective option outdoors.
    Those who do not implement the wet methods described above, or 
those grinding indoors, have the option to use a dust collector 
equipped with a commercially available shroud and dust collection 
system. Several rulemaking participants testified on the commercial 
availability of such equipment, including Gerry Scarano, Executive Vice 
President of BAC, Deven Johnson, director of training, health and 
safety for the Operative Plasterers and Cement Masons International 
Association, and Francisco Trujillo of Miller and Long (Document ID 
3581, Tr. 1562, 1592-1593; 3585, Tr. 2962-2964). The record shows that 
Makita, DeWalt, Bosch, and Ostec all make grinding dust collection 
systems (see Chapter IV of the FEA).
    The LEV-based exposure controls for surface grinding function 
similarly to the LEV-based controls for mortar removal described in 
paragraph (c)(1)(xi) of the standard for construction, as mortar 
removal (tuckpointing) is simply a specialized form of grinding that 
uses the same grinding tools. The factors that influence vacuum flow 
rate for mortar removal (tuckpointing) are equally important to LEV 
dust controls for all types of surface grinding, and for other hand-
operated power tools as well. Collingwood and Heitbrink note that 
``vacuum cleaners will probably continue to be an important control 
option for respirable dust exposures in construction for dust exposure 
sources such as mortar removal, concrete grinding, hole drilling, and 
brick cutting where water application is impractical'' (Document ID 
0600, p. 884). Older studies of LEV effectiveness have found exposure 
reductions of 86-99 percent (Document ID 0611, p. 463; 0247, pp. 6, 8). 
A more recent study by Akbar-Khanzadeh et al. found silica dust 
exposure reduced by 98-99 percent, depending on the vacuum type used 
(Document ID 3609, p. 707). Akbar-Khanzadeh and Brillhart and Echt and 
Sieber both reported reduced silica exposures when workers used LEV 
shrouds with vacuum attachments during surface grinding, although the 
silica exposure results were variable and some exceeded 50 [micro]g/
m\3\ even with use of the controls (Document ID 0521, pp. 344-345; 
0632, pp. 459-460).
    OSHA received a number of comments about the proposed entry on 
Table 1 for handheld (or hand-operated) grinders using LEV. The 
proposed entry specified use of a grinder with a commercially available 
shroud and dust control system. Several commenters questioned why 
shrouds needed to be commercially available and whether appropriate 
shrouds are, in fact, commercially available (e.g., Document ID 2319, 
p. 105; 2316, p. 2; 2171, p. 9). Francisco Trujillo from Miller and 
Long stated ``dust collection systems used on hand grinders received 
very disappointing results. In fact, no hand grinder equipped with a 
dust collection system was capable of bringing exposure levels below 
the current [i.e., the preceding] PEL'' (Document ID 3585, Tr. 2963). 
He further explained that this was due to the limited capabilities of 
the dust collection systems maintaining complete surface contact during 
the frequent grinding of columns and walls (Document ID 3585, Tr. 2963-
2964). However, he found that a vacuum system designed for use with 
ceiling grinders ``greatly reduced the amount of dust expelled from the 
process but did not completely eliminate it. It was a very, very dusty 
activity, and now it's moderately so'' (Document ID 3585, Tr. 2962). He 
reported that although all sampling results were below the preceding 
PEL, three out of five samples were still above 50 [micro]g/m\3\. He 
also reported that none of the hand grinders with dust controls that 
Miller and Long evaluated were effective with columns and wall corners 
and that even with these LEV systems, the same number of workers were 
in Miller and Long's respiratory protection program (Document ID 3585, 
Tr. 2962-2964, 3012).
    In Section 5.11 of Chapter IV of the FEA, OSHA's exposure profile 
shows that 60 percent of ceiling grinders who perform overhead grinding 
using LEV, and 50 percent of outdoor grinders using LEV or water have 
achieved exposures below 50 [micro]g/m\3\, while 25 percent of other 
grinders working indoors with LEV have achieved exposures below 50 
[micro]g/m\3\. These results demonstrate that exposures of 50 [micro]g/
m\3\ or below are achievable with technology available at the time of 
sampling. Much of the data in the exposure profile reflects samples 
collected over ten years ago, before many of the engineering studies 
described in the FEA were conducted. OSHA expects that capture 
technology will continue to improve in response to market demand.
    In addition, Gerry Scarano, representing BAC, stated that since 
2009, ``the availability and effectiveness of control options have 
improved, adding force to OSHA's conclusion that it is feasible to 
reduce the dust in most cases down to the proposed PEL'' (Document ID 
3581, Tr. 1562). Thus, the effectiveness of controls available today is 
likely higher than those that were used when the exposure samples 
included in the exposure profile were obtained.
    SMI commented that there are no commercially available dust shrouds 
that currently meet American National Standards Institute (ANSI) B7.1 
(and OSHA) guard design requirements (Document ID 2316, p. 2). SMI 
stated that available dust shrouds are plastic and are used in place of 
the original equipment's steel guards but do not meet the requirements 
of ANSI B7.1, which is a safety design specification standard for 
grinding wheels (Document ID 2316, p. 2). However, NIOSH reported that 
several major tool manufacturers sell grinders with integrated dust 
shrouds designed to meet applicable safety standards, and the tools are 
labeled accordingly. For example, the Underwriter's Laboratory

[[Page 16744]]

(UL) mark carried by the products of several manufacturers signifies 
that their tools meet the requirements of ANSI/UL/CSA 60745-2-3, which 
incorporates ANSI B7.1 by reference (Document ID 4233, Attachment 1, p. 
8). Catalogs of tool manufacturers submitted to the docket by NIOSH 
include grinders that meet this standard and other tools that bear the 
SA approval mark of the Canadian Standards Association, an OSHA 
Nationally Recognized Testing Lab (NRTL, described under 29 CFR 1910.7) 
(Document ID 3998, Attachment 10, pp. 7-9, 15, 45). OSHA anticipates 
that, once there is a market demand, additional tool manufacturers will 
offer shrouds meeting these machine guarding requirements. OSHA finds 
that compliant shrouds are already commercially available, and will not 
create a greater hazard.
    In the proposed standard, OSHA specified that the dust collection 
system must have an air flow of at least 25 cfm per inch of wheel 
diameter. OSHA has maintained this requirement in the final standard. 
CISC commented that for larger blades, it may be difficult to design 
and operate a system that pulls air flow at 25 cfm per inch of blade 
diameter (Document ID 2319, p. 105). NAHB also expressed concern that a 
dust collector with a HEPA vacuum would need to be at least 112.5 cfm 
for a small, 4.5-inch grinder (Document ID 2296, Attachment 1, p. 29). 
PTI recommended revising the Table 1 entry for grinders to require use 
of vacuums equipped with a HEPA filter that operates at 80 cubic feet 
per minute or greater, noting that commercial dust collection systems 
are typically rated at approximately 130 cfm (Document ID 1973, pp. 2-
3). BCTD, on the other hand, recommended that OSHA specify airflow 
rates for grinder LEV based on blade diameter (Document ID 2371, p. 
32). As explained above in the discussion of grinders used for mortar 
removal, OSHA has determined that 25 cfm per inch of blade diameter is 
more protective and consistent with established engineering principles 
as reflected in the ACGIH Industrial Ventilation Manual, 28th Edition, 
which generally expresses minimum cfm requirements for a variety of 
(stationary) grinders in relation to the wheel diameter (Document ID 
3883, pp. 13-147--13-152).
    To adequately capture debris during the grinding, OSHA is requiring 
that dust collection systems used with grinders have a filter with 99-
percent or greater efficiency, along with either a cyclonic pre-
separator to collect large debris before the air reaches the filters or 
a filter-cleaning mechanism. Because the same factors that cause air 
flow to decline during tuckpointing affect air flow during other tasks 
such as surface grinding, the measures discussed in the section on 
grinders used for mortar removal also need to be used when surface 
grinding to minimize filter clogging.
    Echt and Sieber reported respirable quartz concentrations ranging 
from 44 [micro]g/m\3\ to 260 [micro]g/m\3\ during two to three hour 
surface grinding tasks with LEV at a construction site. Each day, one 
or two 18-pound bags of debris were collected in a vacuum cleaner. The 
investigators measured actual air flow rates three times over the 
course of five sampling days, reporting an air flow range from 86 to 
106 cfm (Document ID 0632, pp. 459-460). As noted in the discussion of 
LEV controls required for handheld grinders for mortar removal 
(tuckpointing), Heitbrink and Santalla-El[iacute]as also reported that 
air flow is affected by filter loading (Document ID 0731, p. 383). 
Using more extensive measurements (continuous data logging every 8 
seconds), Collingwood and Heitbrink evaluated the same vacuum model 
used by Echt and Sieber and found that average initial air flow was 71 
cfm, which declined to 48 cfm over the task-based work sessions, even 
with knocking the dust from filters using the manufacturer's 
recommended method as deemed necessary (Document ID 0600, p. 884). As 
previously discussed, the accumulation of material and debris on the 
filter (filter caking) during work causes pressure losses that 
eventually limit air flows in even the most powerful vacuums. As debris 
accumulates, the filter becomes caked with collected dust and air flow 
decreases. Unless the filter is properly cleaned according to the 
manufacturer's instructions, the air flows declines rapidly.
    OSHA included three additional specifications in the proposed 
standard; two of these, preventing wet slurry from accumulating and 
drying, and ensuring that visible dust was not emitted from the 
process, were completely removed as described above. OSHA is retaining 
the third specification, which requires employers to minimize the 
accumulation of visible airborne dust when working indoors or in 
enclosed areas by providing sufficient ventilation when needed; this 
requirement is now located in paragraph (c)(2)(i) of the standard for 
construction.
    In the proposed standard, OSHA required the use of a half-mask 
respirator with an APF of 10 during wet grinding for more than four 
hours. No respiratory protection was required when wet grinding for 
four hours or less. When using a grinder equipped with a commercially 
available dust collection system, OSHA required the use of a half-mask 
respirator with an APF of 10 regardless of task duration. In the final 
standard, OSHA has decided it is appropriate to distinguish between 
respiratory protection needed when grinding outdoors and grinding 
indoors or in enclosed areas. This division has allowed OSHA to more 
appropriately apply the use of respirators, limiting the number of 
tasks that requires their usage. Based on data in the record, OSHA 
concludes that most employees using hand-operated grinders without 
controls currently experience exposures above 50 [micro]g/m\3\ TWA. 
However, when grinders are operated with dust collection or wet systems 
outdoors, exposures will be reduced to or below 50 [micro]g/m\3\ most 
of the time. The exposure profile in Table IV.5.11-B in Section 5.11 of 
Chapter IV of the FEA shows that 50 percent of grinders working 
outdoors using water or LEV are exposed below 50 [mu]g/m\3\. These 
results demonstrate that silica exposures at or below 50 [mu]g/m\3\ 
have already been achieved for half of exposed workers with technology 
available at the time of sampling. Much of the data in the exposure 
profile reflects samples collected over ten years ago, before many of 
the engineering studies described in the FEA were conducted. OSHA 
expects that dust capture technology will continue to improve in 
response to market demand. When fully and properly implemented, OSHA 
expects that exposures to silica will be at or below 50 [mu]g/m\3\ most 
of the time when water-based dust suppression or LEV systems are used 
for outdoor grinding and that respiratory protection will not need to 
be relied on to protect employees.
    The available data presented in Table IV.5.11-B in Section 5.11 of 
Chapter IV of the FEA suggest that the mean indoor grinding exposure 
level with dust collection systems is about twice that for grinding 
outdoors, with 50 percent of exposures between 100 and 250 [micro]g/
m\3\. Exposures measured within a test chamber during grinding 
operations confirm that high exposures result from grinding concrete 
indoors, even with good dust collection equipment (Document ID 3609), 
with mean task-based sample results generally falling between 100 and 
200 [micro]g/m\3\. Based on the available data for indoor grinding, 
OSHA concludes that, when grinding with a commercially available shroud 
and dust collection system for four hours or less per shift, resulting

[[Page 16745]]

exposures should generally be no higher than grinding outdoors for a 
full shift and thus should not necessitate the use of respiratory 
protection. However, for indoor grinding tasks performed more than four 
hours per shift, the Agency concludes that exposures will consistently 
exceed 50 [micro]g/m\3\. Therefore, Table 1 requires respiratory 
protection with an APF of at least 10 when grinding with dust 
collection systems for more than four hours per shift indoors or in an 
enclosed area.
    OSHA finds that there is inadequate evidence in the record to 
demonstrate that wet grinding indoors or in an enclosed area is as 
effective as using LEV. Accordingly, OSHA is permitting the use of 
water-based dust control for grinding tasks outdoors only and is not 
requiring the use of respiratory protection regardless of the duration 
of the task. OSHA notes from its exposure profile that the vast 
majority of exposure samples taken during indoor grinding where dust 
controls were used made use of LEV systems rather than water-based dust 
control systems (21 out of 23 samples) (see Section 5.11 of Chapter IV 
of the FEA). If an employer decides to use a wet method for indoor 
grinding, it will be operating outside of Table 1 and will have to 
comply with the paragraph (d) alternative method of compliance.
    Walk-behind milling machines and floor grinders. Paragraph 
(c)(1)(xiii) of the standard for construction requires walk-behind 
milling machines and floor grinders used to grate or grind solid 
surfaces (such as concrete, asphalt, masonry walls and sidewalks, see 
Section 5.8 of Chapter IV of the FEA) to be equipped with an integrated 
water delivery system that continuously feeds water to the cutting 
surface, or with a dust collection system recommended by the 
manufacturer of the milling machine or floor grinder, a filter with 99 
percent or greater efficiency, and a filter-cleaning mechanism. When 
using an LEV dust collector system indoors or in enclosed areas, Table 
1 also requires that loose dust be cleaned with a HEPA-filtered vacuum 
in between passes of the milling machine or floor grinder. Both options 
require that the tool be operated in accordance with the manufacturer's 
instructions to minimize dust emissions. No respiratory protection is 
required by Table 1, regardless of task duration or work location.
    Paragraph (c)(1)(xiii) of the standard for construction covers 
wheeled machines, equipped with a cutting tool, that are guided by hand 
with the worker positioned more than an arm's length away from the 
grinding action of the tool (e.g., milling machines, scarifiers, floor 
grinders). Laborers or construction workers operate these machines 
during specialty tasks such as resurfacing floors, repairing pavement, 
or creating grooves for electrical cables (Document ID 0036, p. 15; 
3958; 3959, p. 39). In the proposed standard, walk-behind milling 
machines were included under the entry for ``Milling'' as ``walk-behind 
milling tools.'' In response to commenters' recommendations, and 
recognizing that suitable dust control measures differ among different 
milling machines, OSHA has decided it is more appropriate to divide 
milling activities into three subgroups: Walk-behind machines and floor 
grinders, small drivable milling machines (less than half-lane), and 
large drivable milling machines (half-lane and larger) (Document ID 
3583, Tr. 2171, 2212-2213; 2181, pp. 4, 7, 9).
    Walk-behind milling machines and floor grinders are currently 
available with water systems (e.g., Document ID 0524; 0642), and with 
dust collection systems (e.g., Document ID 1276; 0636; 0642; 4073, 
Attachment 4a, Rows 131-133, 150-152). Additionally, some scarifiers, 
particularly those intended for indoor use, are available with both a 
vacuum port (for connecting to a portable industrial vacuum system) and 
a water mist system as standard equipment (Document ID 0642).
    In specifying the option for a machine equipped with an integrated 
water delivery system that continuously feeds water to the cutting 
surface, OSHA is not specifying a minimum flow rate for water used with 
the integrated delivery system, but rather anticipates that the water 
flow rates specified by the manufacturer will optimize dust reduction. 
Evidence in the record demonstrates the effectiveness of wet methods to 
control exposures when using walk-behind milling machines and floor 
grinders. ERG (2000) measured exposure levels below the LOD (12 
[micro]g/m\3\) for workers using wet methods while milling a newly 
installed terrazzo floor indoors (Document ID 0200, p. 11). Echt et al. 
(2002) tested a custom-built water-fed system that provided a copious 
amount of water (15 gallons per minute) to the concrete work surface 
(not the cutting teeth) milled by a scabbler with an 8-inch cutting 
width. The investigators compared results from alternating 5-minute 
periods of milling with and without the water-feed activated. The water 
reduced average respirable dust levels by at least 80 percent. A 
separate NIOSH study on drivable milling machines reports that under 
common road milling conditions, water spray provided to the cutting 
drum area at 12 gallons per minute is capable of suppressing dust 
generated by a 7-foot wide (84 inches) drivable milling machine cutting 
drum (an application rate of just 0.14 gallons per minute per inch of 
cutting width) (Document ID 1251, pp. 7-9, 14). Based on this evidence, 
OSHA concludes that, with careful adjustment, water spray methods using 
a fraction of the water used in the Echt et al. (2002) scabbler study 
should prove at least as effective in reducing silica dust exposures 
generated by walk-behind milling machines and floor grinders.
    Blute et al. (1999) evaluated silica exposures among workers using 
wet dust control methods for scabbling and large-scale grinding tasks 
at an underground construction site. In this case, rather than being 
walk-behind equipment, the scabblers and grinders were attached to the 
articulated arm of front-end loaders (Document ID 0562, p. 633). 
Although these workers used drivable machines (removing more material 
than the typical walk-behind milling machine), their work (scabbling 
and grinding excess concrete from tunnel walls) demonstrates the value 
of wet methods when these activities are performed in enclosed spaces. 
This is particularly relevant to walk-behind milling machines that are 
frequently used indoors to mill concrete surfaces. In the underground 
work environment, all three workers experienced task-based silica 
concentrations below the preceding PEL with only one of the results (79 
[micro]g/m\3\) exceeding 50 [micro]g/m\3\ (Document ID 0562, p. 637). 
OSHA has determined that the information discussed above and in the FEA 
is the best available evidence and supports the use of wet methods to 
control silica dust while using walk-behind milling machines.
    Alternatively, employers following Table 1 may use a machine 
equipped with a dust collection system recommended by the manufacturer. 
The similarity between vehicular and walk-behind milling machines 
supports the use of vacuum dust collection (exhaust suction) methods 
for the smaller, walk-behind form of milling equipment. A study by TNO 
Bouw (2002) found that when exhaust suction methods were applied to the 
milling drum area of drivable milling machines, exposure levels for 
operators obtained over a five-day period ranged from less than 4 
[micro]g/m\3\ to 28 [micro]g/m\3\. The study also found similar 
exposure results for machine tenders, who walked next to the machines; 
results ranged from less than 3 [micro]g/m\3\ to 29 [micro]g/m\3\ 
(Document ID 1184, p. 25). OSHA inspection data from a construction 
site using a scarifier and

[[Page 16746]]

a floor grinder, both equipped with LEV, to mill a concrete floor found 
no silica exposure for either of the workers (Document ID 3958, Rows 
209-211, 214-215). OSHA's exposure profile, contained in Section 5.8 of 
Chapter IV of the FEA, contains these and four other exposure results 
for workers using walk-behind equipment at two indoor construction 
sites using LEV, where only one detectable result exceeded 50 [micro]g/
m\3\.
    Based on the evidence in the record, OSHA has determined that 
employees' exposure when using walk-behind milling machines can be 
further reduced by cleaning up debris when work is performed indoors or 
in enclosed areas. During a study on exposures while operating a 
scabbler in a parking garage, researchers noted that the worker 
generated the most airborne dust when passing the machine over a 
previously milled area (Document ID 0633, pp. 812-813). OSHA's OIS data 
also contains a non-detectable silica exposure result for a helper who 
vacuumed behind the operator of a floor grinder and scarifier preparing 
an indoor concrete floor for painting where LEV was used as the dust 
control (Document ID 3958, Row 211). Under paragraph (c)(1)(xiii) of 
the standard for construction, when using a walk-behind milling machine 
or floor grinder indoors or in an enclosed area, milling debris in the 
form of loose dust must be removed with a HEPA-filtered vacuum prior to 
making a second pass over an area. This prevents the debris from 
interfering with the seal between machine and floor and minimizes the 
gap. Additionally, it prevents debris from being re-suspended and 
acting as another source of exposure. Accordingly, OSHA is requiring 
the use of a vacuum with a HEPA filter to clean up any loose dust prior 
to making additional passes over the area when work is conducted 
indoors or in enclosed spaces with LEV (Document ID 0633, pp. 812-813; 
1391, pp. 28, 40).
    In addition, the effectiveness of vacuum suction also depends on 
minimizing the gap between the bottom of the machine and the surface 
being milled, as discussed by Hallin (1983), who found that exposures 
to respirable dust increased when the housing around the base of the 
tool was removed (Document ID 1391, p. 25). To achieve acceptable dust 
control and ensure that the LEV system is fully and properly 
implemented, milling must proceed in a manner that limits the gap 
between the bottom of the walk-behind milling machine and the surface 
being milled.
    Based on the data described above, OSHA concludes that most 
employees operating walk-behind milling machines will experience 
exposure levels of 50 [micro]g/m\3\ or below most of the time when 
employers implement the controls outlined in Table 1 under paragraph 
(c)(1)(xiii) of the standard for construction. OSHA finds that controls 
effective for driven milling machines are adaptable to the smaller 
walk-behind milling machines. Even in indoor environments, low 
exposures can be achieved for most walk-behind milling machine 
operators through the proper use of controls, including the use of 
HEPA-filtered vacuum systems intended to clear debris in between 
milling passes when dry grinding and the use of ventilation as required 
under paragraph (c)(2)(i) of the standard for construction. Therefore, 
OSHA concludes that exposure will remain below 50 [micro]g/m\3\ most of 
the time, even when working indoors for more than four hours, and is 
not requiring the use of respiratory protection, regardless of task 
duration or work location.
    Small Drivable Milling Machines (less than half-lane). Employees 
engaged in this task use small drivable milling equipment to grate or 
grind solid surfaces, such as concrete floors, sidewalks, and asphalt 
roads. The smaller drivable machines mill a narrower strip of pavement 
than large milling machines (median of 20 inches compared to a minimum 
of 79 inches for large machines), and typically are capable of milling 
less depth (median 8 inches) than a large machine (median 13 inches) 
(Document ID 1229; 3958). Milling machinery, both large and small, 
often uses a rapidly rotating drum or a bit covered with nibs to abrade 
surfaces, although other mechanisms (including systems based on impact, 
shot-blast, or rotating abrasive cups) are common.
    The proposed standard contained a single entry for ``Milling'' and 
treated all drivable milling machines alike, requiring them to use a 
water-fed system that continuously applied water at the cut point. In 
the final standard, OSHA has separated smaller milling machines (less 
than a half-lane wide) from larger ones based on comment and testimony 
in the record. In response to commenters, OSHA has decided it is more 
appropriate to divide drivable milling activities into separate entries 
for large milling machines (half-lane and larger) and small milling 
machines (less than half-lane) (Document ID, 3583, Tr. 2171, 2212-2213; 
2181, pp. 4, 7, 9). IUOE and a road milling machine manufacturer 
categorized drivable milling machines as either small or large (half-
lane or larger, with cutting drum about 79 inches or wider) (Document 
ID 3583, Tr. 2441; 1229). NAPA commented that large milling machines 
should be identified separately on Table 1 of the construction 
standard. Based on these comments and evidence showing that the dust 
control systems are different between the two classes of drivable 
milling machine (Document ID 3583, Tr. 2171, 2212-2213), Table 1 in the 
final standard treats them as two separate tasks.
    Under paragraph (c)(1)(xiv) of the standard for construction, small 
drivable milling machines (less than a half-lane in width) must be used 
with supplemental water sprays designed to suppress dust. The water 
used must be combined with a surfactant. Manufacturers of smaller 
drivable milling machines currently make such systems (Document ID 
1229; 4073, Attachment 4a). Unlike for larger milling machines, Table 1 
does not specify as an option a water spray and exhaust ventilation 
combination system for small milling machines because it appears that 
such systems are not currently available.
    Including a surfactant additive in the water is a practical way to 
reduce employee exposures to the lowest level achievable with this wet 
method (Document ID 1216, p. 3; 1217, Slides 4 and 8; 3583, Tr. 2187-
2188). This is because it offers particle binding properties that are 
ideal for dust suppression (Document ID 1216, p. 3).
    Small drivable milling machines generally produce less dust than 
large drivable machines, since small machines are used intermittently 
and have smaller cutting tools (Document ID 1229, pp. 1-3; 3583, Tr. 
2213). As discussed in the technological feasibility section on millers 
using portable or mobile machines (see Section 5.8 of Chapter IV of the 
FEA), OSHA concluded that, rather than relying on the very limited 
(two) existing data points for workers using small drivable milling 
machines, the exposure profile for this group is better represented by 
a surrogate data set comprising the more comprehensive and wide ranging 
profile for the entire group of workers using drivable milling machines 
(including operators and tenders/helpers of both large and small 
drivable milling machines). Thus, the exposure profile for small 
drivable milling machines (n = 31) shows a median exposure of 21 
[micro]g/m\3\ and a mean exposure of 48 [micro]g/m\3\, with overall 
exposures ranging from 5 [micro]g/m\3\ to 340 [micro]g/m\3\. Therefore, 
considering the ample evidence on the effectiveness of water-based dust 
control systems for large as well as small drivable milling machines, 
OSHA finds that this control is

[[Page 16747]]

applicable to small drivable milling machines.
    Water applied to the cutting drum helps reduce respirable silica 
exposures among milling machine operators and helpers. In a study 
conducted in the Netherlands, a water spray dust emission suppression 
system using additives reduced the PBZ respirable quartz exposures of 
asphalt milling machine drivers to a mean of 20 [micro]g/m\3\, with a 
range of 9 [micro]g/m\3\ to 30 [micro]g/m\3\ (Document ID 1216, p. 4). 
Milling machine tenders benefitted equally from the system, having a 
mean PBZ respirable quartz exposure of 8 [micro]g/m\3\ with a range of 
4 [micro]g/m\3\ to 12 [micro]g/m\3\. In his comments, Anthony Bodway, 
representing NAPA, stated his belief that employee exposures from 
asphalt road milling machines will be reduced to levels below 50 
[micro]g/m\3\ when milling machines are fitted with effectively 
designed water spray systems paired with surfactants and routine 
inspections to ensure the system components are working properly 
(Document ID 2181, p. 10). He noted that all six major road milling 
machine manufacturers have recently begun, or will soon be, offering 
dust control optimized water spray systems as standard equipment or 
retrofit kits (Document ID 2181, pp. 21-29). One water spray design for 
asphalt pavement milling evaluated by NIOSH showed more promise than 
others, reducing dust release by 38 to 46 percent (Document ID 4141, p. 
26). Although his comment was related to large drivable milling 
machines, wet dust control technology is available for small drivable 
milling machines (Document ID 1229; 4073, Attachment 4a).
    Based on information presented here and in the technological 
feasibility analysis (see Section 5.8 of Chapter IV of the FEA), OSHA 
concludes that employers using the controls required by paragraph 
(c)(1)(xiv) of the standard for construction can reduce exposure levels 
to 50 [micro]g/m\3\ or below for most employees operating or helping 
with small drivable milling machines most of the time. The similarities 
to large drivable milling machines are sufficient to indicate that the 
wet dust suppression control technology is transferable to the smaller 
drivable machines. Even if these smaller machines do not achieve the 
extent of dust suppression demonstrated for larger machines because 
they perform specialty milling operations and not flat removal of 
asphalt typically performed by large drivable machines prior to laying 
of new asphalt, the intermittent nature of operations for which small 
drivable milling machines are used will help to maintain 8-hour TWA 
exposure levels substantially lower than they would be for continuous 
operation (Document ID 3583, Tr. 2213-2215). Therefore, OSHA is not 
requiring the use of respiratory protection regardless of task duration 
when using small drivable milling machines (less than half-lane) 
equipped with supplemental water sprays combined with a surfactant.
    Large drivable milling machines (half-lane or larger). Paragraph 
(c)(1)(xv) of the standard for construction has three control options 
for employers operating large (one-half lane or wider) milling 
machines. When making cuts of four inches in depth or less on any 
substrate, the control options are either to use a machine equipped 
with exhaust ventilation on the drum enclosure and supplemental water 
sprays designed to suppress dust or a machine equipped with 
supplemental water spray designed to suppress dust combined with a 
surfactant. When milling only on asphalt, Table 1 allows cuts of any 
depth to be made when machines are equipped with exhaust ventilation on 
the drum enclosure and supplemental water sprays designed to suppress 
dust.
    These controls are currently available (Document ID 2181, pp. 11, 
21-29). All of the manufacturers of large milling machines currently 
provide dust-suppressing water spray systems on new equipment and as 
retrofit kits for older machines. In addition, as discussed in the 
Section 5.8.4 of Chapter IV of the FEA, new machines will be equipped 
with both dust-suppressing water spray systems and dust collection 
systems by 2017 at the latest, when industry members are committed 
under the Silica/Asphalt Milling Machine Partnership, which includes 
representatives from the road construction contractors industry and 
major road milling machine manufacturers, NAPA, AEM, IUOE, LHSFNA, and 
NIOSH, to equip new machines with both dust-suppressing water spray 
systems and LEV (Document ID 2181, pp. 11, 21-29).
    The controls included on Table 1 for large drivable milling 
machines are based on research on dust control technologies conducted 
by the Silica/Asphalt Milling Machine Partnership, which has been 
studying dust controls for milling machines since 2003 (Document ID 
2181, pp. 1-2; 3583, Tr. 2152, 2160; 4149) with the goal to develop 
innovative engineering controls ``that all but eliminate dust and 
potential silica exposure,'' and methods ``to retrofit existing milling 
machines to ensure a safe workplace'' (Document ID 3583, Tr. 2153). 
Much of the data contained in the record on the effectiveness of 
control strategies for large drivable milling machines come from the 
Partnerhip's efforts and are contained in NIOSH publications (see Table 
IV.5.8-B in Section 5.8 of Chapter IV of the FEA).
    Based on the data in the record, exposures among large drivable 
milling machine operators can be reduced to 50 [micro]g/m\3\ or less 
most of the time. The exposure profile in Section 5.8 of Chapter IV of 
the FEA shows that 79 percent of all large drivable milling machine 
operators already experience silica levels below 50 [micro]g/m\3\ as a 
result of using water spray intended to cool the cutting drum. 
Similarly, exposure levels for 67 percent of tenders working alongside 
large milling machines are below 50 [micro]g/m\3\. Based on the 
Agency's review of studies in the record, which show that low silica 
exposures can be achieved for both operators and tenders across varying 
water spray flow rates, OSHA concludes that improvements to cooling 
water spray systems can help to further reduce exposures of employees 
currently experiencing exposures above 50 [micro]g/m\3\ (see Tables 
IV.5.8-D and IV.5.8-E in Section 5.8 of Chapter IV of the FEA). 
However, information is insufficient to confirm that the use of water 
alone in existing systems will reliably control all employees' 
exposures. Based on the Agency's review of evidence in the rulemaking 
record, OSHA has determined that supplementing water with a dust 
suppressant additive or with an exhaust ventilation on the drum 
enclosure (controls that were not included on proposed Table 1), will 
achieve levels below 50 [micro]g/m\3\ for all or almost all operators 
and helpers most of the time when making cuts of four inches in depth 
or less on any substrate (see Table IV.5.8-E in Section 5.8 of Chapter 
IV of the FEA) (Document ID 1216, p. 4; 4147, pp. v, 13; 4149, pp. v, 
13). Additionally, OSHA has determined that when milling asphalt only, 
the addition of exhaust ventilation on the drum enclosure will achieve 
levels below 50 [micro]g/m\3\ for workers making cuts of any depth 
(Document ID 4149).
    NIOSH recommended LEV plus water-spray dust suppression controls be 
included on Table 1 for drivable milling machines (Document ID 2177, 
Attachment B, p. 20). As discussed in Section 5.8.4 of Chapter IV of 
the FEA, a dust suppression system with a foam additive kept exposures 
below 30 [micro]g/m\3\, and the use of water sprays combined with LEV 
systems kept exposures under 25 [micro]g/m\3\ (Document ID 1184, pp. 5, 
25; 1217, p. 4). These methods, combined with water spray

[[Page 16748]]

systems purposefully designed to control dust at the cutting drum, 
transfer points, and conveyors, will control silica exposures among 
vehicular milling machine operators and tenders to 50 [micro]g/m\3\ or 
below during typical removal operations under the typical range of 
conditions. Manufacturers of large milling machines are committed under 
the Silica/Asphalt Milling Machine Partnership to equip new machines 
with both dust-suppressing water spray systems and LEV by 2017 
(Document ID 2181, pp. 11, 21-29). Until such time that new machines 
equipped with LEV and water dust suppression systems are available, all 
six major road milling machine manufacturers have recently begun, or 
will soon be, offering dust control optimized water spray systems as 
standard equipment and/or retrofit kits, which are expected to meet the 
requirements for Table 1 for cuts of four inches in depth or less on 
any substrate (Document ID 2181, pp. 21-29).
    Proposed Table 1 specified the use of a respirator (half-mask APF 
10) for drivable milling machines with a water-fed system used more 
than four hours a day irrespective of the material milled. NAPA 
recommended removing the proposed requirements for use of respirators 
when milling asphalt (Document ID 2181, pp. 11-12, 16). Upon review of 
the evidence in the record, OSHA agrees that this is appropriate for 
all asphalt and concrete milling operations. As explained in Section 
5.8 of Chapter IV of the FEA, the controls contained in Table 1 in the 
final standard will keep exposures below 50 [micro]g/m\3\ for most 
operators and tenders of large drivable milling machines most of the 
time. Evidence submitted to the record by NAPA and NIOSH shows both 
water-based dust suppression systems and combination LEV/water-based 
systems during asphalt milling results in employee exposures lower than 
50 [mu]g/m\3\ (Document ID 2177 Attachment B, p. 20; 1184, pp. 5, 25; 
1217, p. 4). Accordingly, respiratory protection is not required under 
Table 1 of the final standard for operating large drivable milling 
machines to mill asphalt. Although there is some qualitative evidence 
indicating that exposures when milling concrete for more than four 
hours may be somewhat higher, and could exceed 50 [mu]g/m\3\ some of 
the time, there is no hard data permitting OSHA to treat asphalt and 
concrete milling differently with respect to imposing a respirator 
requirement or to conclude that most concrete milling for that duration 
will be above 50 [mu]g/m\3\ most of the time. Therefore, OSHA is not 
including a respirator requirement in the final standard for either 
asphalt or concrete milling, regardless of task duration.
    IUOE recommended separate treatment of operators and tenders of 
large milling machines since the exposures of operators are lower than 
the exposures of tenders. IUOE further stated that operators are 
located farther from the silica source than tenders, and appropriate 
protection varies depending upon the location of the worker from the 
silica source (Document ID 2262, p. 24). Evidence summarized above 
shows that most tenders and operators will not experience silica 
exposures in excess of 50 [mu]g/m\3\ when either of the control options 
required by Table 1 is implemented. The exposure profile in Table 
IV.5.8-C in Section 5.8 of Chapter IV of the FEA shows that the mean of 
respirable crystalline silica exposures for operators of large milling 
machines is 39 [micro]g/m\3\ (median 17 [micro]g/m\3\) and the slightly 
higher mean for tenders is 57 [micro]g/m\3\ (median 27 [micro]g/m\3\). 
Sample results presented in the exposure profile indicate that 79 
percent of all large drivable milling machine operators already 
experience silica levels below 50 [micro]g/m\3\ as a result of using 
water spray intended to cool the cutting drum. Similarly, exposure 
levels for most tenders (67 percent) working alongside large milling 
machines are already below 50 [micro]g/m\3\ (see Tables IV.5.8-D and 
IV.5.8-E in Section 5.8 of Chapter IV of the FEA). Therefore, OSHA 
concludes that separate control measures do not need to be specified 
for operators and tenders.
    Proposed Table 1 contained dust control specifications for all 
drivable milling machines, including when milling concrete. OSHA 
received comments from IUOE, BCTD, and NAPA recommending that Table 1 
be modified to separate asphalt milling and concrete milling and 
require appropriate controls based on the respective exposure levels 
(Document ID 2262, pp. 3, 17; 2371, Attachment 1, p. 26; 2181, p. 9). 
Concrete milling is performed less frequently than asphalt milling 
(Document ID 1231; 3583, Tr. 2213-2214), but silica exposures could be 
higher than when milling asphalt. This difference is likely due to the 
potential for the silica content to be higher in some concrete compared 
with some asphalts (Document ID 1699), and also the softness and 
``stickiness'' of asphalt milled warm, which likely helps reduce 
separation of the pavement components and perhaps limits dust release 
in hot weather (Document ID 1251, p. 14; 1231). In addition, cutting 
drums for concrete have smaller teeth, which can produce more fine dust 
than is the case with asphalt (Document ID 1699). Anthony Bodway, 
representing NAPA, also noted that silica exposures are higher for 
concrete milling than for asphalt milling (Document ID 2181, p. 15). In 
the FEA, OSHA concludes that water dust suppression and LEV systems 
should be equally effective for concrete and asphalt in terms of 
percent reduction in dust emissions when making cuts of four inches in 
depth or less on any substrate (see Section 5.8 of Chapter IV of the 
FEA). However, to the extent that milling concrete is dustier (i.e., a 
larger amount of respirable dust is liberated), exposures to silica 
during concrete milling may be somewhat higher than is the case for 
asphalt milling even with the use of dust controls. As previously 
explained, however, OSHA lacks quantitative data supporting these 
comments to allow it to impose more stringent requirements, 
specifically a requirement to use respirators, on concrete milling and 
not on asphalt milling or to conclude that exposures will be over the 
PEL for most operators most of the time doing either task.
    The Silica/Asphalt Milling Machine Partnership conducted field 
trials for large road milling machine LEV systems making cuts up to 11 
inches deep (Document ID 4147; 4149). NIOSH evaluated exposures among 
workers at four road construction sites (Document ID 4147, pp. v, 5-7, 
13, Table 1; 4149, pp. v, 5-7, 13, Table 1). All the samples obtained 
during the studies for operators and tenders combined showed that 
exposure levels never exceeded 25 [mu]g/m\3\ when workers used machines 
fitted with the LEV system, even when making cuts up to 11 inches deep 
in asphalt (Document ID 4147, pp. v, 6-7, 13, Table 1; 4149, pp. v, 5-
7, 13, Table 1). In fact, the highest sample result (24 [mu]g/m\3\ for 
a ``groundsman'' walking beside a milling machine removing 11 inches of 
pavement on each pass) was the only sample result to exceed 13 [mu]g/
m\3\ during the two sampling dates (Document ID 4147, pp. v, 5-7, 13, 
Table 1; 4149, pp. v, 5-7, 13, Table 1). Therefore OSHA is confident 
that when removing asphalt only, workers can make cuts of any depth 
without elevated exposures to silica.
    However, other evidence contained in the record indicates that 
cutting depths of more than four inches, in one pass, reduces the 
effectiveness of controls (Document ID 3798, pp. 2, 14; 0555, p. 1). 
Therefore OSHA has determined that if an employer is using a large 
drivable milling machine to mill concrete, or road surface material 
that contains both concrete and asphalt, deeper than four

[[Page 16749]]

inches, it is not covered by Table 1 and the employer will be required 
to conduct exposure assessments and comply with the PEL in accordance 
with paragraph (d) of the standard for construction.
    IUOE also recommended excluding road demolition and asphalt 
reclamation from asphalt milling in Table 1. Road demolition involves 
removal of the road substructure in addition to the road surface 
material and asphalt reclamation involves deeper cuts than typical 
``mill and fill'' cuts of four inches in depth or less. IUOE asserted 
that this change should eliminate the need for respirator use by 
operators during typical asphalt ``mill and fill'' operations when 
engineering controls are properly implemented (Document ID 2262, p. 
23).
    Paragraph (c)(1)(xv) of the standard for construction excludes road 
demolition and asphalt reclamation operations by limiting milling 
activities on materials other than asphalt to cuts of four inches in 
depth or less. The NIOSH studies of LEV for drivable milling machines 
were conducted using large asphalt road milling machines (half-lane or 
wider) and provide strong evidence that exposure levels below 50 [mu]g/
m\3\ (and even below 25 [mu]g/m\3\) can be achieved for employees 
operating this type of equipment during typical shallow ``mill and 
fill'' type road milling (i.e., cuts of four inches in depth or less) 
(see Table IV.5.8-E in Section 5.8 of Chapter IV of the FEA). In one 
NIOSH study, the removal of excess pavement during milling machine 
demolition-type work (12 inches of pavement all at once), created a 
large gap between the road and the milling machine drum enclosure, 
allowing more dust to escape than during typical milling conditions 
(Document ID 0555, p. 1). Also, a NIOSH trial, using only drum cooling 
water and alternate spray nozzles, showed elevated silica exposure 
levels when the road milling machine intermittently ground through the 
asphalt layer into an aggregate and concrete underlayment (Document ID 
3798, pp. 2, 14). Milling operators will rarely encounter these ``worst 
case'' conditions (Document ID 0555, p. 1).
    As previously stated, when milling only on asphalt, OSHA is 
allowing cuts of any depth to be made when machines are equipped with 
exhaust ventilation on the drum enclosure and supplemental water sprays 
designed to suppress dust. When milling all other material to a depth 
of more than four inches Table 1 does not apply and employers will be 
required to conduct exposure assessments and comply with the PEL in 
accordance with paragraph (d) of the standard for construction. 
Additionally, road demolition, such as cutting the roadway into 
manageable size pieces or squares that involves equipment other than 
milling machines, such as saws, dowel drills, and various kinds of 
heavy equipment, is not covered under this entry on Table 1 (see 
Sections 5.3, 5.6, and 5.9 of Chapter IV of the FEA). In those 
instances employers will need to follow the appropriate entries on 
Table 1 for the equipment used or conduct exposure assessments and 
comply with the PEL in accordance with paragraph (d) of the standard 
for construction.
    Crushing machines. Crushing machines are used to reduce large 
rocks, concrete, or construction rubble down to sizes suitable for 
various construction uses (see Section 5.10 of Chapter IV of the FEA). 
When using crushers, paragraph (c)(1)(xvi) of the standard for 
construction requires the use of equipment designed to deliver water 
spray or mist for dust suppression at crusher and other points where 
dust is generated (e.g., at hoppers, conveyors, sieves/sizing or 
vibrating components, and discharge points), and a remote control 
station or ventilated booth that provides fresh, climate-controlled air 
to the operator. In the proposed standard, OSHA listed this entry as 
``Rock Crushing.'' For the final standard OSHA has revised the title of 
this entry to clarify that it includes concrete crushing, which is 
often performed at demolition projects (Document ID 4073, Attachment 
9a; 4073, Attachment 10a; 4073, Attachment 10b; 4234, Attachment 1, pp. 
15-16). Proposed Table 1 would have required the use of wet methods or 
dust suppressants or LEV systems at feed hoppers and along conveyor 
belts. Information contained in the record indicates that LEV alone is 
not effective in reducing exposures to 50 [mu]g/m\3\ or below, and that 
it is necessary to require both a water spray system and either a 
remote control station or filtered control booth to protect the 
operator and employees engaged in crushing operations (see Section 5.10 
of Chapter IV of the FEA).
    Wet spray methods can greatly reduce the exposure levels of 
operators and laborers who work near crushers tending the equipment, 
removing jammed material from hoppers, picking debris out of the 
material stream, and performing other tasks (Document ID 0203, pp. 3-6, 
9; 1152; 1360; 1431, pp. 3-93-3-94; 3472, pp. 61-76; 4073, Attachment 
9a; 4073, Attachment 15g, p. 1). These systems are currently available 
and all crushers and associated machinery (conveyors, sizing screens, 
discharge points) can be retrofitted with water spray or foam systems 
(Document ID 1360; 0769; 0770; 0830; 0831; 0832). Spray systems can be 
installed for remote control activation (Document ID 0203, pp. 11, 12, 
14; 0830). The design and application of water spray systems will vary 
depending on application. For airborne dust suppression, spray nozzles 
should be located far enough from the target area to provide coverage 
but not so far so as to be carried away by wind. In addition, nozzles 
should be positioned to maximize the time that water droplets interact 
with airborne dust. Droplet size should be between 10 and 150 [mu]m 
(Document ID 1540, pp. 62-63). Alternatively, to prevent airborne dust 
from being generated, nozzles should be located upstream of dust 
generation points and positioned to thoroughly wet the material, and 
the volume and size of droplets increased to ensure that the material 
is sufficiently wetted (Document ID 1540, pp. 62-63). Information from 
IUOE, BCTD, and the U.K. Health and Safety Executive shows that water 
application can be expected to reduce exposure levels from 78 to 90 
percent (Document ID 1330, p. 94; 4025, Attachment 2; 4073, Attachment 
9a, pp. 1-4; 4073, Attachment 15g, p. 2).
    The record did not contain information on exposures of tenders or 
other employees working near a crusher operation without dust controls. 
However, OSHA concludes that employees assisting with crusher 
operations can be exposed to elevated levels of respirable crystalline 
silica if water sprays are not used to control dust emissions. This 
conclusion is based on evidence gathered by OSHA's contractor, ERG, 
which visited a concrete crusher site. At the site, ERG observed a 
crusher operator who spent time outside of a control booth shoveling 
dried material from under a conveyor. The operator was exposed to 54 
[mu]g/m\3\ TWA despite the time he spent in the booth where the silica 
concentration was non-detectable (Document ID 0203, p. 9). Thus, this 
operator's TWA exposure to silica can be entirely attributed to his 
work around the crusher, much as a tender would have been doing. 
Without the benefit of spending some time in the booth, and the fact 
that the material being crushed was wet from rain and a freeze the 
night before, the operator's exposure could have been even higher 
(Document ID 0203). This indicates that tenders assisting with crusher 
operations, who do not have the benefit of a booth for protection from 
exposure, can be exposed to excessive levels of crystalline silica-
containing dust when

[[Page 16750]]

water is not applied to areas where dust emissions occur. The potential 
exposure of tenders and other employees who are in the vicinity of 
crusher operations underscores the importance of using water spray 
systems to reduce dust emissions. Such systems will reduce dust 
exposures generally, thereby reducing exposures for tenders and other 
employees in the vicinity of the crusher. Moreover, as discussed below, 
OSHA is not specifying the use of LEV systems for crushing operations 
on Table 1 of the final standard because LEV has not been proven to be 
an effective or widely available alternative.
    CISC argued that OSHA's preliminary finding that it was feasible to 
achieve exposures of 50 [mu]g/m\3\ for tenders was unfounded and based 
on no data on exposures of crushing machine tenders (Document ID 2319, 
pp. 62-63). However, there are data in the record that inform the 
Agency with respect to exposure of crushing machine tenders and the 
effectiveness of dust controls in reducing their exposures to silica. 
As described above, a crusher operator performing tasks along the 
conveyor belt was exposed much as a tender would be. OSHA identified 
one exposure measurement from an enforcement case for a laborer working 
near a mobile crusher at an asphalt plant; the laborer's exposure was 
43 [mu]g/m\3\ (8-hour TWA) based on a half-day of sampling (Document ID 
0186, pp. 60-61). In addition to assisting with the crusher operation, 
he also mixed a blend of sand, crushed concrete, asphalt, and soil, 
which likely contributed to his exposure. He was working about 50 feet 
from the crusher hopper where it was evident from the inspection report 
that his exposure was much lower than that of the operator (Document ID 
0186, p. 37). Bello and Woskie found exposures of demolition workers, 
including those near a crushing operation, were below 50 [mu]g/m\3\ 
when water was used as dust controls for the demolition project 
(Document ID 4073, Attachment 9a, pp. 3-4). OSHA thus rejects CISC's 
contention that the absence of direct evidence of exposures to tenders 
means that OSHA cannot regulate them or draw reasonable inferences 
about the technological feasibility of controlling their exposures 
(Document ID 2319, pp. 62-63).
    Crushers are currently available with remote controls as standard 
equipment (Document ID 0770; 0769, p. 2). The remote operation permits 
the operator to stand back from the crusher or move upwind of dust 
emissions. IUOE provided exposure data from large highway 
reconstruction projects (Document ID 4025, Attachment 2, p. 9). Four 
samples were collected where the operator platform was next to the 
crushing operation and the operator was directly exposed to the crusher 
emissions, resulting in a mean respirable crystalline silica exposure 
of 410 [mu]g/m\3\ (Document ID 4025, Attachment 2, p. 9). Water use was 
observed but no details were provided on the extent of use or the 
systems in place. There was an approximately 66 percent reduction in 
exposure to respirable crystalline silica of the crusher operator 
working from a remote location (the remote location mean exposure was 
140 [mu]g/m\3\) (Document ID 4025, Attachment 2, p. 9). IUOE addressed 
the utility of remote controls in its comments on the proposed 
standard, and requested that OSHA evaluate remote control technologies 
as an exposure control method and include this type of control in Table 
1 (Document ID 2262, p. 45; 3583, Tr. 2341).
    An isolated and ventilated operator control booth can significantly 
reduce the respirable silica exposures of employees associated with 
crushing. At a visit to a crusher facility, ERG found non-detectable 
levels of respirable crystalline silica inside the operator's control 
booth, compared to a concentration of 103 [mu]g/m\3\ outside, despite 
the booth having poor door seals, using recirculated rather than fresh 
air, and having foam filters (as opposed to the MERV-16 or better 
filters required by paragraph (c)(2)(iii)(E) of the standard for 
construction) (Document ID 0203, pp. 12-13).
    Other studies of operator cabs also reported silica or dust 
exposure reductions ranging from 80 percent to greater than 90 percent 
(Document ID 0589, p. 3; 0590, p. 54; 1431, p. 3-95). In the PEA, OSHA 
recognized that control booths for crushers are commercially available, 
although they are not commonly used on construction sites (Document ID 
1720, p. IV-494). However, Kyle Zimmer, director of health and safety 
for IUOE Local 478, stated during the hearing that ``contractors report 
that they are using portable crusher control booths with air 
conditioning to operate the plant remotely'' (Document ID 3583, Tr. 
2341).
    Evidence indicates that operators experience high exposure levels 
when they must operate the crusher from above the feed hopper where 
dust emissions are highest (Document ID 0030; 4073, Attachment 10a). In 
light of this evidence, OSHA concludes that removing or isolating the 
operator from this high-exposure location will be effective in lowering 
the exposure of the operator. It is not clear that a control booth 
alone will be sufficient to protect the operator from exposure to 
silica, since operators periodically leave the booth to perform work 
around the crusher, and the booth does not offer any protection for 
other employees outside the booth such as tenders. A study of crushers 
used in the South Australian extraction industry found operator 
exposures ranged from 20 to 400 [mu]g/m\3\ (with a median of 65 [mu]g/
m\3\) while crushing dry material and using control booths or cabs 
(Document ID 0647). Four of the eight sample results were at or below 
50 [mu]g/m\3\, and at least two of the sampled workers occasionally 
exited the cabins to free machinery blockages (Document ID 0647).
    Because providing a filtered booth for the operator will not 
protect other employees assisting with the operation or working nearby, 
OSHA finds that a water-based dust suppression system is necessary to 
prevent excessive exposure to silica among tenders and other employees 
nearby. Therefore, OSHA has determined that the combination of water 
use and either a remote control station or a ventilated booth for the 
mobile crusher operator will be effective in minimizing exposure of the 
operators and tenders. Summary data submitted by IUOE show that, with 
water use, the addition of remote control stations further reduced 
operator exposures by a factor of 3 (Document ID 4025, Attachment 2, p. 
9). At the crusher operation visited by ERG, the operator's TWA 
exposure was 54 [mu]g/m\3\ while working in a booth, and his exposure 
would have been lower had water been applied to dried material he was 
shoveling from under the conveyor.
    In the proposed standard, OSHA required the use of a half-mask 
respirator with an APF of 10 for all employees outside of the cab, 
regardless of task duration or whether water sprays or LEV were 
implemented. No respiratory protection was required for those employees 
who operated the crusher from within the cab. OSHA proposed to require 
respirator use because the data available at the time suggested that 
neither water spray nor LEV systems would consistently reduce exposures 
to 50 [mu]g/m\3\ or less, and that high exposures (even in excess of 
the preceding PEL) could still occur. The crushing machine entry for 
Table 1 in the final standard does not require respiratory protection 
for tenders or mobile crusher operators because the evidence described 
above indicates that the use of water systems, combined with a remote 
control station or ventilated

[[Page 16751]]

booth, will reduce most employees' exposures to respirable silica to 50 
[mu]g/m\3\ or less most of the time.
    Information from IUOE, BCTD and the U.K. Health and Safety 
Executive show that water application can be expected to reduce 
exposure levels by 78 to 90 percent (Document ID 1330; 4025, Attachment 
2, pp. 7-23; 4073, Attachment 9a, pp. 1-4; 4073, Attachment 15g, p. 2). 
Using the mid-point of this exposure control range (84 percent) and 
applying it to the highest value in the exposure profile (300 [mu]g/
m\3\), would yield an exposure of slightly less than 50 [mu]g/m\3\ TWA 
for an eight-hour work day. However, other evidence suggests that wet 
spray methods may not consistently achieve exposures below 50 [mu]g/
m\3\ (Document ID 0030; 4025, Attachment 2, pp. 7-23), although little 
detail was available on how water was applied. The evidence is clear 
that the highest exposures occur at the hopper where material is fed by 
front-end loaders or another conveyor, an area that is most likely to 
be tended by the operator (Document ID 0030; 4073, Attachment 10a; 
0203). Therefore, OSHA finds that it is also necessary to use a remote 
control station or filtered booth to ensure the protection of crusher 
operators.
    The use of LEV systems was discussed in the NPRM, but evidence in 
the record indicates that it has yet to be proven practicable for 
mobile construction crushing equipment and is not currently used 
extensively. William Turley of the Construction and Demolition 
Recycling Association stated, ``While there are crushing operations 
that have used baghouses on the crusher, none use . . . ventilation 
equipment for conveyors'' (Document ID 2220, p. 2). Phillip Rice of 
Fann Contracting contended that large crushing systems with multiple 
conveyor belts would make it very difficult to use LEV cost effectively 
(Document ID 2116, Attachment 1, p. 31). In contrast, Kyle Zimmer of 
IUOE testified that employers are using dust collectors with baghouses 
at some crushing operations (Document ID 3583, Tr. 2341). Nevertheless, 
the record does not contain substantial and convincing evidence that 
LEV alone can be applied when using mobile crushing machines to reduce 
exposure levels to the same extent as water-based dust suppression 
systems combined with the use of remote control stations or filtered 
control booths. Therefore, OSHA is not specifying the use of LEV 
systems for crushing operations on Table 1 of the final standard.
    Heavy equipment and utility vehicles used to abrade or fracture 
silica containing materials (e.g., hoe-ramming, rock ripping) or used 
during demolition activities involving silica-containing materials. 
Employees engaged in this task operate a variety of wheeled or tracked 
vehicles ranging in size from large heavy construction equipment, such 
as bulldozers, scrapers, loaders, cranes and road graders, to smaller 
and medium sized utility vehicles, such as tractors, bobcats and 
backhoes, with attached tools that are used to move, fracture, or 
abrade rock, soil, and demolition debris (see Section 5.3 of Chapter IV 
of the FEA). For example, equipment operators typically perform 
activities such as the demolition of concrete or masonry structures, 
hoe-ramming, rock ripping, and the loading, dumping, and removal of 
demolition debris, which may include the loading and dumping of rock, 
and other demolition activities (see Table IV.5.3-A in Section 5.3 of 
Chapter IV of the FEA).
    Paragraph (c)(1)(xvii) of the standard for construction requires 
the operator to be in an enclosed cab, regardless of whether other 
employees are in the area and the cab must meet the requirements of 
paragraph (c)(2)(iii) of the standard for construction. When other 
employees are engaged in the task, water, dust suppressants, or both 
combined must also be applied as necessary to minimize dust emissions. 
Paragraph (c)(2)(iii) of the standard for construction requires 
enclosed cabs to be kept as free as practicable from settled dust, to 
have door seals and closing mechanisms that work properly, to be under 
positive pressure maintained through continuous delivery of fresh air, 
to have gaskets and seals that are in good condition and work properly, 
to have intake air that is filtered through a filter that is 95 percent 
efficient in the 0.3-10.0 [mu]m range, and to have heating and cooling 
capabilities.
    In the proposed Table 1, OSHA included one entry for heavy 
equipment and required that an enclosed cab be used. Although OSHA 
analyzed all types of work with heavy equipment, including demolition, 
in its preliminary feasibility analysis for heavy equipment, the 
proposed Table 1 entry described the activity as ``use of heavy 
equipment during earthmoving activities.''
    Several commenters requested clarification on what uses of heavy 
equipment OSHA intended to cover in the entry on proposed Table 1. IUOE 
requested that OSHA include a definition of the range of ``activities 
encompassed within earthmoving,'' and specifically acknowledge whether 
or not demolition activities are intended to be encompassed within this 
definition of earthmoving on Table 1 (Document ID 2262, p. 7). IUOE 
further explained that while earthmoving activities are ``dust-filled'' 
and likely to result in some exposure to respirable silica, it was 
inappropriate to combine earthmoving and demolition into one entry for 
heavy equipment operators on Table 1 because earthmoving ``does not 
fracture or abrade silica-containing materials, and thus, does not 
expose any heavy equipment operators to [a] high concentration of 
respirable silica.'' IUOE opined that treating the two tasks separately 
in the final rule would allow for better control of the hazards 
(Document ID 2262, pp. 3, 6, 9, 14). LHSFNA supported the IUOE position 
on demolition versus earthmoving and how it should be addressed in 
Table 1 (Document ID 4207, p. 3). BCTD requested that Table 1 specify 
that the Table 1 controls only apply when the listed task is performed 
on or with silica-containing materials, noting that some operations, 
such as earthmoving equipment, do not generate silica dust unless the 
material contains silica (Document ID 2371, p. 24).
    OSHA agrees with these recommendations and has separated heavy 
equipment into two entries on Table 1: Paragraph (c)(1)(xvii) of the 
standard for construction covers heavy equipment and utility vehicles 
used to abrade or fracture silica-containing materials or during 
demolition activities; paragraph (c)(1)(xviii) of the standard for 
construction covers heavy equipment and utility vehicles used for tasks 
such as grading and excavating (but not including demolishing, 
abrading, or fracturing silica-containing materials). As explained 
below, only heavy equipment and utility vehicles used to abrade or 
fracture silica-containing materials or during demolition activities 
require an enclosed cab at all times, whereas the employer has a choice 
between an enclosed cab or applying water and/or dust suppressant when 
these vehicles are used for tasks such as grading and excavating, 
provided there are no other employees engaged in the task beside the 
heavy equipment operator.
    In the proposed standard, the only control option for heavy 
equipment was to operate from within enclosed cabs. Several commenters 
noted that enclosed cabs do not protect other employees, such as 
laborers, who perform tasks in the area but remain outside the cab 
(e.g., Document ID 2262, p. 24). Fann Contracting explained that not 
including laborers on Table 1 would ``render the table pointless 
because employers would have to conduct

[[Page 16752]]

frequent exposure assessments of those employees'' (Document ID 2116, 
Attachment 1, p. 3). Because of the reasonable concerns raised by these 
commenters, OSHA has included controls (water and/or dust suppressants) 
on Table 1 to protect employees, other than the operator, who are 
engaged in the tasks. The other employees included under this entry for 
Table 1 are typically laborers who work nearby supporting the heavy 
equipment operator (i.e., applying dust suppressant, spotting, and 
clearing debris). When these materials contain crystalline silica, dust 
generated during these activities is a primary source of exposure for 
the equipment operators and the laborers.
    NUCA expressed concern that operating from within a fully enclosed 
cab may reduce visibility of the work zone and impair verbal 
communication. and thereby pose potential safety risks (Document ID 
2171, pp. 2, 4, 22). However, modern heavy equipment already come 
equipped with enclosed, filtered cabs that are designed with visibility 
in mind to allow the operator to perform the work required. 
Furthermore, radios or cell phones can be used for communication if 
necessary. Therefore, OSHA concludes that filtered, fully enclosed cabs 
have been and can continue to be used without compromising worker 
safety or the effectiveness of the cab.
    The exposure profile in Table IV.5.3-B in Section 5.3 of Chapter IV 
of the FEA shows that approximately 8 percent (1 out of 13 samples) of 
heavy equipment operators performing demolition, abrading, or 
fracturing activities have exposures above 50 [mu]g/m\3\. OSHA also 
found a mean TWA exposure of 25 [mu]g/m\3\ for the six samples in the 
record for laborers who assisted heavy equipment operators by providing 
water for dust control during demolition projects. Table IV.5.3-C in 
Section 5.3 of Chapter IV of the FEA compares silica exposures among 
heavy equipment operators with the silica exposures of laborers engaged 
in the same task. These data are a subset of the exposure profile 
(Table IV.5.3-B in Section 5.3 of Chapter IV of the FEA) and provide 
evidence of the effectiveness of applying dust suppressants for dust 
control during demolition activities. The results for the six samples 
for laborers were less than 50 [mu]g/m\3\ and were lower than the heavy 
equipment operators not in an enclosed cab.
    The information presented in OSHA's technological feasibility 
analysis for heavy equipment operators and ground crew laborers 
(Section 5.3 of Chapter IV of the FEA) and summarized above provides 
evidence that the use of enclosed cabs and water and/or dust 
suppressants will reduce exposures to 50 [mu]g/m\3\ or less for 
operators and laborers when these controls are fully and properly 
implemented. Therefore, OSHA is not requiring the use of respiratory 
protection for heavy equipment operators and laborers who assist heavy 
equipment operators during demolition activities involving silica-
containing materials or activities where silica-containing materials 
are abraded or fractured, regardless of the duration of the task. Fann 
Contracting questioned whether operators who use enclosed cabs would be 
required to wear respiratory protection when exiting the equipment cab 
(Document ID 2116, Attachment 1, p. 23). Since the specified control 
method on Table 1 for this task requires the use of an enclosed cab, 
the task is not being performed once the operator exits the enclosed 
cab and the resulting exposure will have ceased, and no respiratory 
protection is required in that circumstance. However, if other 
abrading, fracturing, or demolition work is continuing while an 
operator is outside the cab, that operator is considered to be an 
employee ``engaged in the task'' and must be protected by the 
application of water and/or dust suppressants.
    Heavy equipment and utility vehicles used for tasks such as grading 
and excavating but not including demolishing, abrading, or fracturing 
silica-containing materials. When operating heavy equipment and smaller 
sized utility vehicles for tasks such as grading and excavating that do 
not involve demolition or the fracturing or abrading of silica, 
paragraph (c)(1)(xviii) of the standard for construction requires that 
the employee who will be operating the equipment operate from within an 
enclosed cab or that the employer applies water and/or dust 
suppressants as necessary to minimize dust emissions. If other 
employees (e.g., laborer) are engaged in the task, water and/or dust 
suppressants must be applied as necessary to minimize dust emissions 
even where the operator of the equipment is working inside an enclosed 
cab. However, the employer need not provide an enclosed, filtered cab 
for the operator of the equipment.
    Employees engaged in this task operate a variety of wheeled or 
tracked vehicles ranging in size from large heavy construction 
equipment, such as bulldozers, scrapers, loaders, and road graders, to 
smaller and medium sized utility vehicles, such as tractors, bobcats 
and backhoes, with attached tools that are used to excavate and move 
soil, rock, and other silica-containing materials (see Section 5.3 of 
Chapter IV of the FEA). Typically tasks conducted with this equipment 
include earthmoving, grading, excavating, and other activities such as 
moving, loading, and dumping soil and rock (see Table IV.5.3-B in 
Section 5.3 of Chapter IV of the FEA). In addition, the railroad 
industry uses such heavy equipment to dump and grade silica-containing 
ballast in track work to support the ties and rails. Such track work is 
generally subject to OSHA's construction standards, and the use of 
heavy railroad equipment for this purpose is therefore covered under 
this task in Table 1 of the final standard.
    As discussed under the explanation of (c)(1)(xvii) of the standard 
for construction, OSHA included one entry for heavy equipment operators 
performing earthmoving activities in the proposed standard, but has 
divided this entry to distinguish between the controls needed when 
using heavy equipment for abrading, fracturing, or demolishing silica-
containing material, on the one hand, and for grading and excavating 
silica-containing materials, on the other hand.
    OSHA's exposure profile for earthmoving (i.e., excavation) 
operations shows that a large majority of exposures (87.5 percent) are 
below 25 [mu]g/m\3\ (see Section 5.3 of Chapter IV of the FEA). IUOE 
commented that earthmoving should not be the focus of the rule, stating 
that earthmoving activity ``does not fracture or abrade silica-
containing materials, and thus, does not expose heavy equipment 
operators to high concentrations of respirable silica'' (Document ID 
2262, p. 6). Martin Turek, assistant coordinator and safety 
administrator for IUOE Local 150, stated that ``it is unlikely that 
moving soil or clay will generate respirable silica in concentrations . 
. . above the [proposed] PEL'' (Document ID 3583, Tr. 2358).
    Under both entries, however, the specified controls to protect 
laborers are the same. Thus, as when engaged in abrading, fracturing, 
or demolition tasks near or alongside heavy equipment or utility 
vehicles, OSHA has included a requirement that water and/or dust 
suppressants be applied as necessary to minimize dust emissions so that 
employees, including such laborers, who are engaged in such tasks as 
grading and excavating silica-containing materials in conjunction with 
operators of heavy equipment or utility vehicles are protected from 
excessive exposure to respirable crystalline silica.
    Enclosed cabs are not mandated for this task. They may be used if 
the equipment operator is the only

[[Page 16753]]

employee engaged in the task, as an alternative to water and/or dust 
suppressants. However, where enclosed cabs are used, they must meet the 
requirements outlined in paragraph (c)(2)(iii) of the standard for 
construction. Those requirements specify that enclosed cabs must be 
kept as free as practicable from settled dust, must have door seals and 
closing mechanisms that work properly, must have gaskets and seals that 
are in good condition and work properly, must be under positive 
pressure maintained through continuous delivery of fresh air, must have 
intake air that is filtered through a filter that is 95 percent 
efficient in the 0.3-10.0 [mu]m range, and must have heating and 
cooling capabilities. If employees other than the equipment operator 
are engaged in the task, Table 1 requires the application of water and/
or dust suppressants as necessary to minimize dust emissions, which 
protects the operator as well as the laborers from silica exposures 
above the PEL. As demonstrated by OSHA's exposure profile and the other 
evidence in OSHA's technological feasibility for heavy equipment 
operators and ground crew laborers (Section 5.3 of Chapter IV of the 
FEA), wet dust suppression methods (e.g., water or calcium chloride) 
are already a common and effective means for reducing exposures among 
heavy equipment operators and laborers to 50 [mu]g/m\3\ or below.
    Other commenters were concerned about the availability of enclosed 
cabs on heavy equipment used for these types of earthmoving activities. 
NUCA, NAHB, and CISC expressed concern regarding the cab requirements; 
NUCA stated that the majority of earthmoving equipment is ``equipped 
with open canopies or unpressurized cabs'' (Document ID 2171, p. 3; 
2296, p. 32; 2319, p. 114). OSHA understands that some equipment 
currently in use may not be equipped with enclosed, pressurized cabs as 
required by Table 1 when enclosed cabs are used. Where an employer 
chooses not to retrofit existing equipment for grading and excavating, 
it must apply water and/or dust suppressants as necessary to minimize 
dust emissions in order to comply with Table 1. Employers that neither 
choose to retrofit equipment nor suppress dust using water or other 
dust suppressants must comply with the requirements of paragraph (d) of 
the standard for construction.
    Evidence in the record indicates that exposures of employees during 
common excavation and grading operations are likely to remain below 25 
[mu]g/m\3\ most of the time. OSHA has therefore determined that 
respiratory protection is not needed when the employer fully and 
properly implements the controls on Table 1. Fann Contracting 
questioned whether operators who use enclosed cabs would be required to 
wear respiratory protection when exiting the equipment cab (Document ID 
2116, Attachment 1, p. 23). As explained above, there is no requirement 
for respiratory protection when the employee is entering or exiting the 
cab since the task is not being performed at that time. However, if 
other grading or excavation work is continuing while an operator is 
outside the cab, that operator is considered to be an employee 
``engaged in the task'' and must be protected by the application of 
water and/or dust suppressants.
    Drywall finishers. Table 1 of the final rule does not specify 
controls for drywall finishing. In the proposed standard, ``drywall 
finishing (with silica-containing material)'' was an entry on Table 1. 
The control options on proposed Table 1 were to use a pole sander or 
hand sander equipped with a dust collection system or to use wet 
methods to smooth or sand the drywall seam. However, information in the 
rulemaking record indicates that drywall compound currently in use does 
not usually contain silica (Document ID 2296, pp. 32, 36). NAHB 
commented that much of the drywall joint compound currently used in 
residential construction has no or very low silica content and members 
can resolve any concerns regarding silica exposure by making sure to 
use low silica containing product (Document ID 2296, pp. 32, 36). While 
CISC agreed that contractors ``can utilize `silica-free' joint compound 
and perform drywall installation in a manner that creates exposures 
below the proposed PEL,'' it expressed concern that ``silica-free'' 
joint compound may contain more than trace amounts of silica, which 
could result in exposures to silica (Document ID 2319, pp. 38, 43).
    NIOSH tested bulk samples of a commercially available joint 
compound and found up to 6 percent quartz, although silica was not 
listed on the safety data sheet for the product (Document ID 0213, p. 
5). However, in a more recent study, NIOSH determined that three of six 
drywall compounds purchased at a retail store contained only trace 
amounts of silica (less than 0.5 percent) (Document ID 1335, p. iii). 
The researchers concluded that for the most part the results of each 
sample analysis agreed with the composition stated in the 
manufacturers' material safety data sheets (Document ID 1335, pp. 3-4, 
7, 10). OSHA finds that joint compound is more accurately labeled than 
it was in the past, and that manufacturers' labeling and SDSs are the 
best source for determining whether employees may be exposed to silica 
that could become respirable.
    Additionally, the exposure profile includes 15 full-shift, personal 
breathing zone samples of respirable crystalline silica. The median 
exposure is 12 [mu]g/m\3\, the mean is 17 [mu]g/m\3\, and the range is 
8 [mu]g/m\3\ (limit of detection (LOD)) to 72 [mu]g/m\3\, which was the 
only result above 50 [mu]g/m\3\. The 72 [mu]g/m\3\ sample was obtained 
for a worker performing overhead sanding directly above his breathing 
zone (Document ID 1335, p. 13). One other sample exceeded 25 [mu]g/m\3\ 
(Document ID 1335, p. 14). Therefore, because no additional controls 
are needed for most drywall finishers, OSHA has not included an entry 
for drywall finishers in Table 1 in the final standard.
    In the event that the use of silica-free joint compound is not 
possible, or during renovation work where silica-containing joint 
compound might be present, OSHA has determined that there are 
engineering controls, as discussed in Section 5.2 of Chapter IV of the 
FEA, that reduce exposure to respirable crystalline silica to 50 [mu]g/
m\3\ or below. In that situation employers will have to comply with 
paragraph (d) of the standard for construction. Johnston Construction 
Company commented that a requirement for air purifying respirators 
should be included in the rule for one of the dustiest tasks performed 
(Document ID 1951). OSHA agrees that sanding silica-free joint compound 
can potentially generate high levels of respirable nuisance dust that 
does not contain silica and for which respiratory protection may be 
needed in some situations. While high exposures to nuisance dusts may 
result from sanding joint compound, available evidence shows exposures 
to respirable crystalline silica will be low.
    Abrasive blasting. Table 1 of the final standard does not specify 
controls for abrasive blasting; this is unchanged from the proposed 
rule.
    The Society for Protective Coatings (SSPC) requested that abrasive 
blasting be included in Table 1 (Document ID 2120, p. 3). SSPC 
recommended the inclusion of an abrasive blasting entry which 
``simplifies compliance and eliminates the need for measuring workers' 
exposure to silica, while still ensuring adequate protection for 
workers'' (Document ID 2120, p. 3). However, OSHA has determined that 
it is not appropriate to add abrasive blasting to Table 1.
    There are a variety of options available to employers to control

[[Page 16754]]

exposure to respirable crystalline silica during blasting operations. 
As discussed in the technological feasibility analysis (Section 5.1 of 
Chapter IV of the FEA), these include (1) use of abrasive media other 
than silica sand to reduce crystalline silica dust emissions, (2) use 
of wet blasting techniques, (3) use of dust suppressors, (4) use of 
dust collection systems, and (5) use of hydro-blasting technologies 
that avoid having to use abrasive media.
    OSHA has decided that employees will be best protected when 
employers, following the traditional approach set forth in paragraph 
(d) in the standard for construction, choose among these dust control 
strategies to select the controls that best fit the needs of each job. 
OSHA's conclusion is based on the following additional considerations: 
(1) Abrasive blasting operators must, separate from this rule, be 
provided with and wear the respiratory protection required by 29 CFR 
1926.57(f), and (2) employees helping with the operation, or who 
otherwise must be in the vicinity of the operation, must also be 
adequately protected by a combination of engineering controls, work 
practices, and respirators. OSHA thus concluded that the Table 1 
approach did not lend itself to specifying one or more controls that 
would be suitable for all such operations. Furthermore, based on its 
technological feasibility analysis for abrasive blasting (see Section 
5.1 of Chapter IV of the FEA), respirators will be needed whatever 
engineering or work practice control the employer uses under the 
hierarchy of controls to lower silica exposure to the lowest level 
feasible. Accordingly, based on the reasons discussed above, the Agency 
is not mandating a particular dust control approach or approaches for 
abrasive blasting and has therefore not included it as an entry in 
Table 1 of the final standard.

Alternative Exposure Control Methods

    Paragraph (d) of the standard for construction describes the 
requirements for the alternative exposure control methods approach, 
which applies for tasks not listed in Table 1 or where the employer 
chooses not to follow Table 1 or does not fully and properly implement 
the engineering controls, work practices, and respiratory protection 
described in Table 1. The alternative exposure control methods approach 
is similar to OSHA's traditional approach of demonstrating compliance 
with a permissible exposure limit (PEL) through required exposure 
assessments and controlling employee exposures through the use of 
feasible engineering controls and work practices (i.e., the hierarchy 
of controls). With the exception of the option to comply with either 
paragraph (c) or paragraph (d), construction employers are required to 
comply with all other paragraphs of the standard for construction.
    Paragraph (d)(1) specifies that construction employers who must or 
choose to follow paragraph (d) shall limit employee exposures to 
respirable crystalline silica at or below the PEL of 50 [mu]g/m\3\ as 
an 8-hour time weighted average. The PEL is fully discussed in the 
summary and explanation of Permissible Exposure Limit.
    Paragraph (d)(2) specifies the requirements for exposure 
assessments, such as the types of assessments that are required under 
the standard (i.e., performance or scheduled monitoring options), when 
or how often those assessments must be conducted, methods of sample 
analysis, employee notification of results, and the opportunity for 
employees or their representatives to observe monitoring. These 
requirements are fully discussed in the summary and explanation of 
Exposure Assessment.
    Paragraph (d)(3) specifies the methods of compliance, which include 
a requirement to reduce exposure through feasible engineering and work 
practice controls before using respiratory protection, and cross-
references standards for abrasive blasting. These requirements are 
fully discussed in the summary and explanation of Methods of 
Compliance.

Permissible Exposure Limit (PEL)

    Paragraph (c) of the standard for general industry and maritime 
(paragraph (d)(1) in the construction standard) establishes an 8-hour 
time-weighted average (TWA) exposure limit of 50 micrograms of 
respirable crystalline silica per cubic meter of air (50 [mu]g/m\3\). 
This limit means that over the course of any 8-hour work shift, 
exposures can fluctuate but the average exposure to respirable 
crystalline silica cannot exceed 50 [mu]g/m\3\. The PEL is the same for 
both general industry/maritime and construction. The PEL of 50 [mu]g/
m\3\ applies in the construction standard for tasks not listed on Table 
1 or where the employer is not fully and properly implementing the 
specified exposure control methods in paragraph (c) of the standard. 
The PEL of 50 [mu]g/m\3\ does not apply directly to tasks listed on 
Table 1, but the ability to achieve that PEL was the metric by which 
OSHA decided on the specified exposure control(s) listed and whether 
supplementary respiratory protection is required in some or all 
circumstances for a particular task.
    OSHA proposed a PEL of 50 [mu]g/m\3\ because the Agency 
preliminarily determined that occupational exposure to respirable 
crystalline silica at the previous PELs, which were approximately 
equivalent to 100 [mu]g/m\3\ for general industry and 250 [mu]g/m\3\ 
for construction and shipyards, resulted in a significant risk of 
material health impairment to exposed workers, and that compliance with 
the proposed PEL would substantially reduce that risk. OSHA also 
preliminarily found the level of risk remaining at the proposed PEL to 
be significant, but considered a PEL of 50 [mu]g/m\3\ to be the lowest 
level that was technologically feasible overall.
    The PEL was a focus of comment in the rulemaking process, revealing 
sharply divided opinion on the justification for and attainability of a 
PEL of 50 [mu]g/m\3\. Many commenters representing labor unions, public 
health associations, academic institutions, occupational health 
professionals, and others expressed support for the proposed PEL (e.g., 
Document ID 1785, p. 2; 1878, p. 1; 2080, p. 1; 2106, p. 3; 2145, p. 3; 
2166, p. 1; 2173, p. 2; 2178, Attachment 1, p. 2; 2318, p. 10; 2339, p. 
7; 2341, p. 2; 3399, p. 4; 3403, p. 2; 3478, p. 1; 3601, Attachment 2, 
p. 5; 3588, Tr. 3769; 4204, p. 50; 4207, p. 1). Other commenters 
representing a wide range of industries, including construction, 
foundries, concrete, brick and tile manufacturing, mineral excavation, 
utility providers, and others, did not believe the proposed PEL was 
appropriate. Stakeholders also offered opinions on the proposed 
alternative PELs of 25 [mu]g/m\3\ and 100 [mu]g/m\3\.
    Some commenters contended that OSHA's proposed PEL was too low, 
arguing that the proposed limit was infeasible or not justified by the 
health and risk evidence (e.g., Document ID 1964; 1992, pp. 1, 8-10; 
2024, pp. 1-2; 2067, p. 3; 2075, pp. 1-2; 2104, p. 1; 2119, Attachment 
1; 2143, pp. 1-2; 2171, p. 1; 2185, pp. 2-4; 2191, p. 3; 2210, 
Attachment 1, p. 6; 2268; 2269, pp. 2-3; 2279, pp. 2, 9; 2284, p. 2; 
2289, p. 3; 2296; p. 39; 2301, Attachment 1, pp. 7-9; 2305, pp. 4-5, 
15; 2312, p. 2; 2348, Attachment 1, pp. 32-33; 2349, p. 3; 2350, pp. 
10-11; 2384, pp. 2, 9; 2182, pp. 3-4; 2102, pp. 1, 3; 2211, pp. 3-4; 
2283, p. 2; 2250, p. 2; 2288, p. 8; 2300, p. 2; 2338, p. 2; 2356, p. 2; 
2376; 2379, Appendix 1, p. 53; 3275, pp. 1-2). Many of these commenters 
supported the adoption of the proposed alternative PEL of 100 [mu]g/
m\3\.
    Other commenters, including the United Automobile, Aerospace, and 
Agricultural Implement Workers of America and the American Public 
Health Association, contended that the

[[Page 16755]]

remaining risk at 50 [mu]g/m\3\ is excessive and argued that OSHA 
should adopt a PEL of 25 [mu]g/m\3\ or even lower (e.g., Document ID 
2163, Attachment 1, pp. 3, 13; 2176, pp. 1-2; 3577, Tr. 851-852; 3582, 
Tr. 1853-1854; 3589, Tr. 4165; 4236, pp. 5-6). The American Federation 
of Labor and Congress of Industrial Organizations (AFL-CIO) urged OSHA 
to fully evaluate the evidence and set a lower PEL if deemed to be 
feasible (Document ID 3578, Tr. 923-924).
    After considering the evidence in the rulemaking record, OSHA is 
establishing a PEL of 50 [mu]g/m\3\. OSHA's examination of health 
effects evidence, discussed in Section V, Health Effects, and Section 
VI, Final Quantitative Risk Assessment and Significance of Risk, 
confirms the Agency's preliminary conclusion that exposure to 
respirable crystalline silica at the previous PELs results in a 
significant risk of material health impairment to exposed workers, and 
that compliance with the revised PEL will substantially reduce that 
risk. OSHA's Quantitative Risk Assessment indicates that a 45-year 
exposure to respirable crystalline silica at the preceding general 
industry PEL would lead to between 11 and 54 excess deaths from lung 
cancer, 11 deaths from silicosis, 85 deaths from all forms of non-
malignant respiratory disease (including silicosis as well as other 
diseases such as chronic bronchitis and emphysema), and 39 deaths from 
renal disease per 1000 workers. Exposures at the preceding construction 
and shipyard PEL would result in even higher levels of risk. As 
discussed in Section VII of this preamble, Summary of the Final 
Economic Analysis and Final Regulatory Flexibility Analysis, these 
results clearly represent a risk of material impairment of health that 
is significant within the context of the ``Benzene'' decision (Indus. 
Union Dep't, AFL-CIO v. Am. Petroleum Inst., 448 U.S. 607 (1980)). OSHA 
has determined that lowering the PEL to 50 [mu]g/m\3\ will reduce the 
lifetime excess risk of death per 1000 workers to between 5 and 23 
deaths from lung cancer, 7 deaths from silicosis, 44 deaths from non-
malignant respiratory disease, and 32 deaths from renal disease.
    The Agency considers the level of risk remaining at the revised PEL 
to be significant. However, based on the evidence evaluated during the 
rulemaking process, OSHA has determined a PEL of 50 [mu]g/m\3\ is 
appropriate because it is the lowest level feasible. As discussed in 
Chapters IV and VI of Final Economic Analysis and Final Regulatory 
Flexibility Analysis (FEA) and summarized in Section VII of this 
preamble, the PEL is technologically and economically feasible for all 
industry sectors, although it will be a technological challenge for 
several affected sectors and will require the use of respirators for 
certain job categories and tasks. As guided by the 1988 ``Asbestos'' 
decision (Bldg & Constr. Trades Dep't v. Brock, 838 F.2d 1258, 1266 
(D.C. Cir. 1988)), OSHA is including additional requirements in the 
rule to further reduce the remaining risk. OSHA anticipates that the 
ancillary provisions in the rule will further reduce the risk beyond 
the reduction that will be achieved by the PEL alone.
    OSHA has also determined that the proposed alternative PELs, 100 
[mu]g/m\3\ and 25 [mu]g/m\3\, are inappropriate. As noted above, 
significant risk to employees' health exists at the previous PELs, and 
at and below the PEL of 50 [mu]g/m\3\. Because OSHA has determined that 
a PEL of 50 [mu]g/m\3\ is technologically and economically feasible, 
the Agency concludes that setting the PEL at 100 [mu]g/m\3\--a level 
the Agency knows would continue to expose workers to significant risk 
of material impairment to their health greater than is the case at 50 
[mu]g/m\3\--would be contrary to the mandate in the OSH Act, which 
requires the Secretary to promulgate a standard

. . . which most adequately assures, to the extent feasible, on the 
basis of the best available evidence, that no employee will suffer 
material impairment of health or functional capacity even if such 
employee has regular exposure to the hazard dealt with by such 
standard for the period of his working life (29 U.S.C. 655(b)).

Thus, the Agency has rejected the proposed alternative PEL of 100 
[mu]g/m\3\.
    Even though OSHA's risk assessment indicates that a significant 
risk also exists at the revised action level of 25 [mu]g/m\3\, the 
Agency is not adopting the alternative PEL of 25 [mu]g/m\3\ because a 
PEL of 50 [mu]g/m\3\ is the lowest exposure limit that can be found to 
be technologically feasible for many of the industries covered by the 
rule. Specifically, OSHA has determined that the information in the 
rulemaking record either demonstrates that the proposed alternative PEL 
of 25 [mu]g/m\3\ would not be achievable for most of the affected 
industry sectors and application groups or the information is 
insufficient to conclude that engineering and work practice controls 
can consistently reduce exposures to or below 25 [mu]g/m\3\. Therefore, 
OSHA cannot find that the proposed alternative PEL of 25 [mu]g/m\3\ is 
achievable for most operations in the affected industries (see Section 
VII of this preamble and Chapter IV of the FEA). Moreover, OSHA also 
concludes that it would hugely complicate both compliance with and 
enforcement of the rule if it were to set a PEL of 25 [mu]g/m\3\ for a 
minority of industries or operations where it would be technologically 
feasible and a PEL of 50 [mu]g/m\3\ for the remaining industries and 
operations where technological feasibility at the lower PEL is 
demonstrably unattainable, doubtful or unknown.
    Instead, OSHA has concluded that a PEL of 50 [mu]g/m\3\ is 
economically and technologically feasible for all of the affected 
industries and has decided to exercise its discretion to issue this 
uniform PEL to avoid the enormous compliance and enforcement 
complications that would ensue if it were to bifurcate the PEL (see 
Section II, Pertinent Legal Authority, discussing the chromium (VI) 
decision). Other issues related to OSHA's adoption of a PEL of 50 
[mu]g/m\3\ are discussed below. The discussion is organized around the 
following topics: Coverage of quartz, cristobalite, and tridymite; the 
PEL as a gravimetric measurement of respirable dust; industry-specific 
PELs; enhanced enforcement; environmental sources of crystalline silica 
exposure; collection efficiency; coal dust; and CFR entries.
    Coverage of quartz, cristobalite, and tridymite. As discussed in 
the summary and explanation of Definitions, the PEL applies to the 
three forms of crystalline silica (i.e., quartz, cristobalite, and 
tridymite) covered under previous OSHA PELs. Specifically, paragraph 
(b) of the rule defines the term ``respirable crystalline silica'' to 
mean

. . . quartz, cristobalite, and tridymite contained in airborne 
particles whose measurement is determined by a sampling device 
designed to meet the characteristics for particle-size-selective 
samplers specified in International Organization for Standardization 
(ISO) 7708:1995: Air Quality--Particle Size Fraction Definitions for 
Health-Related Sampling.

    The proposed definition of respirable crystalline silica also would 
have established a single PEL that would have encompassed the three 
forms of silica covered under the previous OSHA silica PELs. While 
commenters generally supported a single PEL for respirable crystalline 
silica, they did not all agree on whether a single PEL should include 
quartz, cristobalite, and tridymite (e.g., Document ID 1731, p. 2; 
2315, p. 9). Some commenters argued that the PEL should include all 
three forms; some suggested that the single PEL should be for only 
quartz and cristobalite (e.g., Document ID 2177, Attachment B, p. 10; 
2196, Attachment

[[Page 16756]]

1, p. 5; 3403, p. 4; 4212, p. 3) or only quartz (e.g., Document ID 
2185, p. 6). NIOSH noted that ``tridymite is extremely rare in 
workplaces, so a separate PEL probably cannot be supported by 
epidemiologic evidence and may not be warranted for this material 
(Document ID 2177, Attachment B, p. 10). Southern Company argued that

. . . the inclusion of tridymite and cristobalite are not supported 
by the data and, due to their rare nature, serve to unnecessarily 
create upward bias of the exposure evaluations due to the laboratory 
detection limitations (Document ID 2185, p. 2).

    Halliburton Energy Services said that, given that OSHA has 
acknowledged that the risk to workers exposed to a given level of 
respirable crystalline silica may not be equivalent in different work 
environments, OSHA's ``one size fits all'' silica PEL for different 
forms of crystalline silica with varied physicochemical properties was 
unwarranted (Document ID 2302, p. 5).
    As discussed in Section V, Health Effects, OSHA has concluded, 
based on the available scientific evidence, that quartz, cristobalite, 
and tridymite have similar toxicity and carcinogenic potency. The 
Agency therefore concludes that a single PEL is appropriate for quartz, 
cristobalite, and tridymite.
    The PEL as a gravimetric measurement of respirable dust. The 
revised PEL, like OSHA's proposed PEL, is expressed as a gravimetric 
measurement of respirable crystalline silica. The preceding PELs were 
formulas that were inconsistent between industries and forms of 
crystalline silica. For general industry (see 29 CFR 1910.1000, Table 
Z-3), the PEL for crystalline silica in the form of respirable quartz 
was based on two alternative formulas: (1) A particle-count formula 
(PELmppcf = 250/(% quartz + 5) as respirable dust); and (2) 
a mass formula proposed by the American Conference of Governmental 
Industrial Hygienists (ACGIH) in 1968 (PEL = (10 mg/m\3\)/(% quartz + 
2) as respirable dust). The general industry PELs for crystalline 
silica in the form of cristobalite and tridymite were one-half of the 
value calculated from either of the above two formulas for quartz. For 
construction (29 CFR 1926.55, Appendix A) and shipyards (29 CFR 
1915.1000, Table Z), the formula for the PEL for crystalline silica in 
the form of quartz (PELmppcf = 250/(% quartz + 5) as 
respirable dust), which requires particle counting, was derived from 
the 1970 ACGIH threshold limit value (TLV). Based on the formulas, the 
PELs for quartz, expressed as time-weighted averages (TWAs), were 
approximately equivalent to 100 [mu]g/m\3\ for general industry and 250 
[mu]g/m\3\ for construction and shipyards. As detailed in the 
discussion of sampling and analysis in Chapter IV of the FEA, OSHA 
finds that the formula based on particle-counting technology used in 
the preceding general industry, construction, and shipyard PELs has 
been rendered obsolete by respirable mass (gravimetric) sampling.
    A number of commenters supported the proposed switch from these 
formulas to a PEL expressed as a gravimetric measurement of respirable 
crystalline silica. For example, several stakeholders, including the 
American Foundry Society (AFS), the American Petroleum Institute, the 
Fertilizer Institute, and the North American Insulation Manufacturers 
Association, agreed that OSHA should revise the previous formulaic PELs 
into straightforward concentration/gravimetric-based thresholds (e.g., 
Document ID 2101, p. 4; 2145, p. 3; 2278, p. 2; 2301, Attachment 1, p. 
4; 4213, p. 8; 4229, p. 27). Others suggested the previous formulaic 
PELs are confusing, complicated (e.g., Document ID 2175, p. 5; 2185, p. 
2), and outdated (e.g., Document ID 2163, Attachment 1, p. 2; 2204; 
3588, Tr. 3769). Ameren Corporation also expressed support for the 
elimination of the PELs calculated based on the percent silica in the 
sample (Document ID 2315, p. 8).
    After considering the record on this issue, OSHA has decided to 
adopt a PEL which is expressed as a gravimetric measurement of 
respirable crystalline silica. OSHA expects that the revised PEL will 
improve compliance because the PEL is simple and relatively easy to 
understand, and is consistent with modern sampling and analytical 
methods. In addition, OSHA finds that a uniform PEL will provide 
consistent levels of protection for workers in all sectors covered by 
the rule.
    Industry-specific PELs. Some commenters urged OSHA to take an 
industry-specific approach to regulating respirable crystalline silica 
exposures. Southern Company urged OSHA to consider a vertical standard 
that addresses industries with known negative health impacts from 
silica-containing materials (Document ID 2185, p. 2). Battery Council 
International asked OSHA to set the PEL based on relevant particle size 
and the size distribution data and recommended that OSHA adjust the PEL 
for different industry segments consistent with these data (Document ID 
2361, pp. 1-2). Other commenters suggested that the PEL should be lower 
for certain industries, such as hydraulic fracturing and dental 
equipment manufacturing (Document ID 2282, Attachment 3, p. 12; 2374, 
Attachment 1, p. 5).
    OSHA considers the level of risk remaining at the new PEL of 50 
[mu]g/m\3\ to be significant. Although OSHA expects the ancillary 
provisions of the standard to reduce this risk below what engineering 
and work practice controls alone can achieve, the Agency realizes that 
lower PELs might be achievable in some industries and operations, which 
would reduce this risk even further. However, as explained below, OSHA 
concludes that the significant costs, including opportunity costs, of 
devoting the resources necessary to attempting to establish and apply 
multiple PELs for the diverse group of industries and operations 
covered by the standard would undermine the value of this reduction 
(see Building & Constr. Trades Dep't v. U.S. Dep't of Labor, 838 F.2d 
1258, 1273 (D.C. Cir. 1988) (administrative difficulties, if 
appropriately spelled out, could justify a decision to select a uniform 
PEL)).
    Requiring OSHA to set multiple PELs--taking into account the 
feasibility considerations unique to each industry or operation or 
group of them--would impose an enormous evidentiary burden on OSHA to 
ascertain and establish the specific situations, if any, in which a 
lower PEL could be reached. Such an onerous obligation would inevitably 
delay, if not preclude, the adoption of important health standards. In 
addition, the demanding burden of setting multiple PELs would be 
complicated by the difficulties inherent in precisely defining and 
clearly distinguishing between affected industries and operations where 
the classification determines legal obligations. The definitional and 
line-drawing problem is far less significant when OSHA merely uses a 
unit of industries and operations for analytical purposes, and when it 
sets a PEL in the aggregate, i.e., when its analysis is limited to 
determining whether a particular PEL is the lowest feasible level for 
affected industries as a whole. If OSHA had to set multiple PELs, and 
assign industries or operations to those PELs, the problem would become 
much more pronounced as the consequences of imprecise classifications 
would become much more significant.
    OSHA also finds that a uniform PEL will ultimately make the 
standard more effective by making it easier for affected employers to 
understand and comply with the standard's requirements. Moreover, a 
uniform PEL makes it

[[Page 16757]]

possible for OSHA to provide clearer guidance to the regulated 
community and to identify non-compliant conditions. For these reasons, 
OSHA has always interpreted Section 6(b)(5) of the Act to accord the 
Agency substantial discretion to set the PEL at the lowest level that 
is feasible for industries and operations as a whole. In adopting the 
arsenic standard, for example, OSHA expressly declined to set different 
PELs, finding that ``[s]uch an approach would be extremely difficult to 
implement'' (43 FR 19584, 19601 (5/5/1978)). In that instance, OSHA 
explained:

    The approach OSHA believes appropriate and has chosen for this 
and other standards is the lowest level achievable through 
engineering controls and work practices in the majority of 
locations. This approach is intended to provide maximum protection 
without excessively heavy respirator use. Id.
    OSHA has also rejected such an approach in rulemakings on 
benzene and chromium (VI).

(see 43 FR 5918, 5947 (2/10/1978); 71 FR 10100, 10337-10338 (2/28/
2006)).

    In the case of cotton dust, where OSHA did set different PELs for 
certain discrete groups, the groups involved exposures to different 
kinds of cotton dust and different degrees of risk. Even so, OSHA did 
not adopt a unique PEL for every single affected sector (see 43 FR 
27350, 37360-37361 (6/23/1978)); OSHA set one PEL for textile 
industries and a separate PEL for non-textile industries, but expressly 
rejected the option of adopting different exposure limits for each non-
textile industry). OSHA recognizes that the exception from the scope of 
this rule for exposures that result from the processing of sorptive 
clays results in a different PEL being enforced in that sector. 
However, the processing of sorptive clays is a very small industry 
sector, and OSHA finds that this sector can be readily segregated from 
other industry sectors covered by the rule.
    Enhanced enforcement. Several commenters suggested retaining the 
preceding PELs and focusing OSHA efforts on enhanced enforcement rather 
than on a new rule (e.g., Document ID 1741, Attachment 1; 2067, p. 4; 
2183, p. 4; 2185, p. 2; 2210, Attachment 1, pp. 3, 7; 2261, pp. 2-3; 
2283, p. 2; 2292, p. 2; 2344, p. 2; 2349, p. 3; 2363, p. 10; 3486, p. 
1; 3496, p. 3). Some of these commenters, such as the Small Business 
Administration's Office of Advocacy, indicated that OSHA data show 
widespread noncompliance with the previous PELs and suggested that 
silica-related illnesses could be linked to noncompliance (e.g., 
Document ID 2349, p. 3). Others, such as Arch Masonry, urged OSHA to 
consider information and testimony about noncompliant work environments 
as evidence of an enforcement problem rather than evidence to support a 
new rule (e.g., Document ID 3587, Tr. 3651-3652). The Mercatus Center 
asked OSHA to explain how improved enforcement of the existing rule is 
not superior to a more stringent PEL (Document ID 1819, p. 9).
    As discussed in Section V, Health Effects, OSHA does not find these 
arguments persuasive. First, many of the commenters used OSHA's 
enforcement data to make this point. These data were obtained during 
inspections where non-compliance was suspected and thus were skewed in 
the direction of exceeding the preceding PELs. As the Building and 
Construction Trades Department, AFL-CIO (BCTD) explained, OSHA data 
showing noncompliance with the preceding PEL is not representative of 
typical exposure levels, since sampling for compliance purposes targets 
worst-case exposure scenarios (Document ID 3581, Tr. 1634-1636).
    Moreover, not all commenters agreed that overexposures were 
``widespread.'' A few other commenters (e.g., AFS) thought that OSHA 
substantially overstated the number of workers occupationally exposed 
above 100 [mu]g/m\3\ in its PEA (Document ID 2379, Attachment B, p. 
25). In either case, OSHA's analysis evaluated risks at various 
exposure levels, as is required by the OSH Act. As noted above, the 
available data indicate that exposure to respirable crystalline silica 
at the preceding PELs results in a significant risk of material health 
impairment among exposed employees. Simply enforcing the preceding PELs 
will not substantially reduce or eliminate this significant risk.
    Exposure Variability. Commenters, including the Asphalt Roofing 
Manufacturers Association (ARMA), argued that because OSHA PELs are 
never-to-be-exceeded limits, employers must maintain average exposures 
well below the PEL to have confidence that exposures are rigorously 
maintained at or below the PEL every day, for every worker (e.g., 
Document ID 2291, pp. 5-7). The Construction Industry Safety Coalition 
(CISC) made a similar argument regarding the need to control exposure 
levels to well below the PEL due to the variability of silica exposures 
on construction worksites in order to assure compliance (Document ID 
4217, p. 12).
    OSHA recognizes that differences in exposure can occur due to 
workplace variables such as fluctuations in environmental conditions or 
air movement. However, many of the major sources of day-to-day 
variability can be moderated by the consistent use of engineering 
controls and appropriate work practices (Document ID 3578, Tr. 971; 
3589, Tr. 4251-4252; 4234, Attachment 2, pp. 31-38).
    OSHA has acknowledged and discussed exposure variability in past 
rulemakings where the same issue was raised (e.g., benzene, 52 FR 
34534; asbestos, 53 FR 35609; lead in construction, 58 FR 26590; 
formaldehyde, 57 FR 22290; cadmium, 57 FR 42102; and chromium (VI), 71 
FR 10099). In its asbestos rulemaking, for example, OSHA found that 
industry's argument about uncontrollable fluctuations was exaggerated 
because such fluctuations could be minimized through proper inspection 
and maintenance of engineering controls and through proper training and 
supervision of employees whose work practices affected exposure levels 
(59 FR 40964, 40967 (8/10/94)). The Agency also noted that its 
enforcement policy gives employers the opportunity to show that a 
compliance officer's measurement over the PEL is unrepresentatively 
high and does not justify a citation, thus alleviating the concern 
employers might have that they will be cited on the basis of a single 
measurement that results from uncontrollable fluctuations (59 FR at 
40967).
    Reviewing courts have held that OSHA's obligation to show that a 
PEL can be achieved in most operations most of the time has been met 
despite the presence of random exposure variability. These courts have 
noted, in particular, OSHA's flexible enforcement policies, which allow 
the Agency to take such exposure variability into account before 
issuing a citation (e.g., Building & Constr. Trades Dept. v. Brock, 838 
F.2d 1258 (D.C. Cir. 1988) (``Asbestos II'')). In the Asbestos II case, 
the D.C. Circuit cited with approval OSHA's policy of allowing for a 
possible re-inspection if OSHA measured an asbestos exposure above the 
PEL during an inspection. If the employer appeared to be using, to the 
extent feasible, appropriate work practices and engineering controls, 
OSHA could agree not to issue a citation at that time based on that 
inspection and to re-inspect at a later time. Such a re-inspection 
would help determine if that over-exposure was typical or simply a 
random, uncontrollable fluctuation; OSHA could then determine whether 
or not to issue a citation accordingly (Asbestos II at 1268; 51 FR 
22653 (6/20/1986)). Thus OSHA has, in the past, adopted fair and 
flexible enforcement policies to deal with the issue of exposure 
variability

[[Page 16758]]

and will do the same for enforcement of the new silica standards.
    Such an enforcement policy recognizes the possibility that OSHA may 
measure silica exposures on a day when exposures are above the PEL due 
to unforeseeable, random exposure variations. In such a case, when the 
employer has previously monitored the work area, OSHA inspectors would 
review the employer's long-term body of data demonstrating the exposure 
pattern for tasks/operations that are representative of those under 
OSHA's evaluation. After comparing the employer's exposure data with 
OSHA's sampling results, OSHA's determination whether to resample would 
be governed by the inspector's judgment of whether the OSHA sampling 
results are representative.
    Where an employer can show, based on a series of measurements made 
pursuant to the sampling and analytical protocols set out in these 
standards or other relevant data, that the OSHA one-day measurement may 
be unrepresentatively high, OSHA may re-inspect the workplace and 
measure exposures again. If, after such a reinspection, OSHA has reason 
to believe that there are circumstances that account for the high 
exposure measurement, OSHA may decide not to issue a citation.
    For OSHA to consider a reinspection rather than citation, an 
employer must demonstrate that the inspector's one-day sample is 
unrepresentative of normal exposure levels. In most cases, this 
demonstration would consist of a series of full shift measurements 
representative of the exposure of the employee under consideration. 
These measurements should consist of all valid measurements related to 
the employee under consideration taken within the last year and should 
show that only on rare occasions could random fluctuations result in 
TWA concentrations above the PEL.
    Environmental sources of crystalline silica exposure. Some 
stakeholders raised concerns about the extent to which crystalline 
silica dust from naturally-occurring environmental sources (e.g., in 
southwestern regions of the United States) might contribute to employee 
exposures to respirable crystalline silica and artificially inflate 
sampling measurements (e.g., Document ID 1785, p. 4; 2116, Attachment 
1, pp. 19-20; 3230, p. 1; 3533, p. 22). SMI cited an EPA study 
published in 1996 (Document ID 3637), and indicated that mean 
concentrations of ambient atmospheric respirable crystalline silica 
across 22 cities in the United States range from 0.9 to 8 [mu]g/m\3\ 
(Document ID 3533, p. 20). OSHA recognizes that there can be occasions 
when environmental sources of silica may affect occupational sampling 
results. However, OSHA notes that the data utilized in the 1996 study 
were originally published in an earlier (1984) journal article by Davis 
et al. (Document ID 3852), and the EPA report included important 
caveats about the environmental data that were available at the time 
(Document ID 3637, pp. 3-29, 3-31--3-34). For example, the section of 
the EPA report on ``Limitations of Current Data'' states:

    The lack of current, direct measures of ambient quartz 
concentrations is a major limitation of the data available for use 
in estimating U.S. ambient silica concentrations (Document ID 3637, 
pp. 3-31).

    The report also indicated that ``. . . another limitation of the 
available data is the fact that neither current nor dated quartz 
measurements were taken using PM10 samplers'' (Document ID 
3637, pp. 3-33).
    In addition, OSHA notes that the sampling methodology used in the 
Davis study does not measure respirable crystalline silica, as defined 
in OSHA's silica rule. Rather, the Davis study presents data from 
dichotomous samplers that are equipped with particle size selection 
inlets. These samplers allow for measurement of two particle size 
fractions: A fine fraction with particle sizes having aerodynamic 
diameter less than 2.5 microns (PM2.5) and a coarse fraction 
designed to eliminate particles greater than about 15 microns in 
aerodynamic diameter (PM15). By contrast, OSHA's definition 
for respirable crystalline silica is tied to an International 
Organization for Standardization (ISO) sampling methodology that has 
different size-specific mass collection efficiencies. Of particular 
importance, the dichotomous samplers from the Davis study collect 
particles with aerodynamic diameters between 10 and 15 microns that are 
generally excluded from the ISO sampling methodology; and the 
dichotomous samplers likely collect a considerably higher portion of 
particles with aerodynamic diameters between 5 and 10 microns.
    OSHA concludes that the sampling results presented in the Davis 
study are not comparable to respirable crystalline silica measurements, 
as defined in OSHA's rule. It is clear that the sampling methodology 
considered in the Davis study would overstate respirable crystalline 
silica levels measured using the ISO sampling methodology. Moreover, 
OSHA has demonstrated that compliance with the PEL is technologically 
feasible. OSHA's evaluation of the technological feasibility of the PEL 
involved evaluation of thousands of respirable crystalline silica 
samples collected in a variety of occupational settings that include 
contributions from environmental sources in different geographic areas. 
Because the exposure data considered by OSHA in its evaluation of the 
technological feasibility of the PEL includes contributions from 
environmental sources, these contributions are already taken into 
account in determining the feasibility of the PEL. Therefore, OSHA 
finds that environmental sources of respirable crystalline silica 
exposure, to the extent they contribute to workplace exposures, are 
already considered in the Agency's conclusion that the revised PEL is 
feasible.
    Collection efficiency. In the rule, OSHA is adopting the ISO/CEN 
particle size-selective criteria for respirable dust samplers used to 
measure exposures to respirable crystalline silica. Several commenters, 
including U.S. Aggregates, the National Industrial Sand Association, 
and the U.S. Chamber of Commerce, argued that moving from the current 
criteria to the ISO/CEN convention effectively decreases the PEL and 
action level below the levels intended, since more dust would be 
collected by samplers that conform to the ISO/CEN convention than by 
those that conform to the current criteria (Document ID 2174; 2195, p. 
30; 2285, pp. 3-4; 2317, p. 2; 3456, p. 10; 4194, pp. 15-16). However, 
as discussed in Chapter IV of the FEA, the Dorr-Oliver 10-mm cyclone 
used by OSHA for enforcement of respirable dust standards conforms to 
the ISO/CEN specification with acceptable bias and accuracy when 
operated in accordance with OSHA's existing method (i.e., measurements 
taken using the Dorr-Oliver 10-mm cyclone following OSHA's existing 
method provide results that are consistent with the ISO/CEN convention, 
and therefore are acceptable for measuring respirable crystalline 
silica exposures under the rule). The change from the previous criteria 
to the ISO/CEN convention is therefore effectively a continuation of 
current practice.
    Coal dust. Southern Company, the American Iron and Steel Institute, 
and Ameren Corporation indicated that revising the respirable 
crystalline silica PEL creates uncertainty with regard to the PEL for 
coal dust, which continues to use the previous criteria for calculation 
of respirable crystalline silica (Document ID 2185, p. 2; 2261, pp. 2, 
5; 2315, p. 8). They urged the Agency to address how the existing coal

[[Page 16759]]

dust PEL will interact with the new PEL and calculation for exposure to 
respirable crystalline silica. For example, Southern Company stated:

. . . it is unclear to us what the expectation would be in 
evaluating and managing exposures to either of these substances when 
the effective source of these exposures is the same. If both PELs 
apply, this would mean duplicate or dual sampling (Document ID 2185, 
p. 2).

Ameren also questioned whether employers would be required to sample 
for both respirable crystalline silica and respirable coal dust on 
workers who are potentially exposed to both substances. Ameren 
suggested that OSHA should consider changing the PELs for amorphous 
silica and coal dust so that they are consistent with the revised PEL 
for respirable crystalline silica (Document ID 2315, pp. 2, 8).
    OSHA clarifies that the respirable crystalline silica rule does not 
change the existing PEL for coal dust. However, as indicated 
previously, the Dorr-Oliver 10-mm cyclone used by OSHA for enforcement 
of respirable dust standards exhibits acceptable bias against the ISO/
CEN specification when operated in accordance with OSHA's existing 
method. Employers can continue to use the Dorr-Oliver cyclone to 
evaluate compliance with the new respirable crystalline silica PEL, as 
well as with the PEL for coal dust; duplicate sampling is not 
necessary. Employers can also use other ISO/CEN-compliant samplers to 
evaluate compliance with either or both PELs.
    CFR entries. The rule revises entries for crystalline silica in 29 
CFR 1910.1000 Table Z-1 to cross-reference the new standard, 1910.1053. 
A comparable revision to 29 CFR 1915.1000 Table Z cross-references 
1915.1053, which in turn cross-references 1910.1053. The entries for 
crystalline silica in 29 CFR 1926.55 Appendix A are revised to cross-
reference 1926.1153. General industry standards are located in Part 
1910; maritime standards are located in Part 1915; and construction 
standards are located in Part 1926.
    The preceding PELs for respirable crystalline silica are retained 
in 29 CFR 1910.1000 Table Z-3, 29 CFR 1915.1000 Table Z, and 29 CFR 
1926.55 Appendix A. Footnotes are added to make clear that these PELs 
apply to any sectors or operations where the new PEL of 50 [mu]g/m\3\ 
is not in effect, such as the processing of sorptive clays. These PELs 
are also applicable during the time between publication of the silica 
rule and the dates established for compliance with the rule, as well as 
in the event of regulatory delay, a stay, or partial or full 
invalidation by the Court.
    While the preceding PELs for respirable crystalline silica in 29 
CFR 1910.1000 Table Z-3 are being retained, the PELs for total 
crystalline silica dust are being deleted. OSHA proposed to delete the 
previous general industry PELs for exposure to total crystalline silica 
dust because development of crystalline silica-related disease is 
related to the respirable fraction of, rather than total, dust exposure 
(see Section V, Health Effects). This view is consistent with that of 
ACGIH, which no longer has a Threshold Limit Value for total 
crystalline silica dust. NIOSH does not have a Recommended Exposure 
Level for total crystalline silica exposure, and neither the National 
Toxicology Program nor the International Agency for Research on Cancer 
has linked exposure to total crystalline silica dust exposure to 
cancer, as they have with respirable crystalline silica exposure.

Exposure Assessment

    Paragraph (d) of the standard for general industry and maritime 
(paragraph (d)(2) of the standard for construction) sets forth 
requirements for assessing employee exposures to respirable crystalline 
silica. The requirements are issued pursuant to section 6(b)(7) of the 
OSH Act, which mandates that any standard promulgated under section 
6(b) shall, where appropriate, ``provide for monitoring or measuring 
employee exposure at such locations and intervals, and in such manner 
as may be necessary for the protection of employees'' (29 U.S.C. 
655(b)(7)).
    Assessing employee exposure to toxic substances is a well-
recognized and accepted risk management tool. The purposes of requiring 
an assessment of employee exposures to respirable crystalline silica 
include: Determination of the extent and degree of exposure at the 
worksite; identification and prevention of employee overexposure; 
identification of the sources of exposure; collection of exposure data 
so that the employer can select the proper control methods to be used; 
and evaluation of the effectiveness of those selected methods. 
Assessment enables employers to meet their legal obligation to ensure 
that their employees are not exposed in excess of the permissible 
exposure limit (PEL) and to ensure employees have access to accurate 
information about their exposure levels, as required by section 8(c)(3) 
of the Act (29 U.S.C. 657(c)(3)). In addition, exposure data enable the 
physicians or other licensed health care professionals (PLHCP) 
performing medical examinations to be informed of the extent of 
occupational exposures.
    In the proposed standard for general industry and maritime, OSHA 
included a requirement for employers to assess the exposure of 
employees who are reasonably expected to be exposed to respirable 
crystalline silica at or above the action level of 25 [micro]g/m\3\. 
This obligation consisted of: An initial exposure assessment, unless 
monitoring had been performed in the previous 12 months, or the 
employer had objective data to demonstrate that exposures would be 
below the action level under any expected conditions; periodic exposure 
assessments, following either a scheduled monitoring option (with the 
frequency of monitoring determined by the results of the initial and 
subsequent monitoring) or a performance option (i.e., use of any 
combination of air monitoring data or objective data sufficient to 
accurately characterize employee exposures); and additional exposure 
assessments when changes in the workplace resulted in new or additional 
exposures to respirable crystalline silica at or above the action 
level. The proposed standard also included provisions for the method of 
sample analysis, employee notification of assessment results, and 
observation of monitoring.
    The proposed standard for construction included the same 
requirements for exposure assessment as the proposed standard for 
general industry and maritime; however, employers were not required to 
assess the exposure of employees performing tasks on Table 1 where the 
employer fully implemented the engineering controls, work practices, 
and respiratory protection specified in Table 1. This exception to the 
general requirement for exposure assessment was intended to relieve the 
construction employer of the burden of performing an exposure 
assessment in these situations, because appropriate control measures 
are already identified.
    Commenters, such as the American Federation of Labor and Congress 
of Industrial Organizations (AFL-CIO), the American Society of Safety 
Engineers (ASSE), the National Industrial Sand Association (NISA), and 
the International Diatomite Producers Association, supported the 
inclusion of an exposure assessment provision in the general industry 
standard (e.g., Document ID 4204, pp. 52-54; 2339, p. 4; 2195, pp. 5-6, 
9-10, 33; 2196, Attachment 1, p. 4), while other commenters, including 
the American Public Health Association (APHA), the National Consumers 
League (NCL) and

[[Page 16760]]

Dr. James Cone, more generally concurred with OSHA's proposed exposure 
assessment requirements (e.g., Document ID 2178, Attachment 1, p. 2; 
2373, p. 2; 2157, p. 7). However, commenters from the construction 
industry, including the National Utility Contractors Association, the 
American Subcontractors Association (ASA), the Leading Builders of 
America (LBA), the Associated Builders and Contractors (ABC), the 
Associated General Contractors of America, Fann Contracting, Inc., the 
National Association of Home Builders (NAHB), and the Construction 
Industry Safety Coalition (CISC), as well as the American Fuel and 
Petrochemical Manufacturers (AFPM), whose members regularly perform 
construction tasks, contended that the proposed exposure assessment 
requirements were unworkable, impractical, or exceedingly expensive due 
to the dynamic construction environment where frequent changes in 
environmental conditions, materials, tasks and the amount of time tasks 
are performed, locations, and personnel would require constant 
assessment and monitoring (e.g., Document ID 2171, p. 2; 2187, p. 5; 
2269, p. 6; 2289, p. 6; 2323, p. 1; 2116, Attachment 1, pp. 13-14; 
2296, pp. 24-25; 2350, p. 10; 3521, p. 7; 4217, pp. 12-13). More 
specifically, commenters, including the Distribution Contractors 
Association and the Sheet Metal and Air Conditioning Contractors 
National Association (SMACNA), expressed concerns about the initial or 
periodic assessment requirements (e.g., Document ID 2309, p. 3; 2226, 
p. 2). Fann Contracting, ASA, and the Edison Electric Institute (EEI) 
argued that initial and periodic exposure assessments do not make sense 
for construction projects where conditions, tasks, and potential 
exposures are constantly changing (Document ID 2116, Attachment 1, pp. 
5, 16; 2187, p. 5; 2357, p. 13).
    Other commenters from both construction and general industry, 
including Ameren Corporation (Ameren), the Concrete Company, the Glass 
Association of North America, the Washington Aggregates and Concrete 
Association, the North American Insulation Manufacturers Association 
(NAIMA), EEI, the National Stone, Sand, and Gravel Association (NSSGA), 
the National Association of Manufacturers (NAM), Lafarge North America 
(Lafarge), the Asphalt Roofing Manufacturers Association (ARMA), and 
NAHB, argued that employers should not be required to conduct air 
monitoring for employees on each shift, for each job classification, 
and in each work area unless differences exist between shifts (e.g., 
Document ID 2315, p. 3; 2317, p. 2; 2215, p. 9; 2312, p. 2; 2348, 
Attachment 1, p. 39; 2357, p. 23; 2327, Attachment 1, p. 18; 2380, 
Attachment 2, pp. 26-28; 2179, p. 3; 2291, pp. 20-21). The American 
Foundry Society (AFS) argued that repetitious full shift sampling is 
also ``burdensome and unnecessarily dangerous to employees who must 
wear heavy and awkward equipment during the sampling session'' 
(Document ID 2379, Attachment B, p. 28). Commenters from the 
construction industry, including ABC, LBA, the Hunt Construction Group, 
and CISC argued that conducting air monitoring for employees on each 
shift, for each job classification, and in each work area or 
representative sampling of employees was not possible in constantly 
changing construction environments (e.g., Document ID 2289, p. 6; 2269, 
p. 6; 3442, pp. 2-3; 2319, pp. 83-84).
    In response to these comments, OSHA restructured the exposure 
assessment requirements in order to provide employers with greater 
flexibility to meet their exposure assessment obligations using either 
the performance option or the scheduled monitoring option. This 
restructuring emphasizes the performance option in order to provide 
additional flexibility for employers who are able to characterize 
employee exposures through alternative methods. Commenters, including 
Arch Masonry, Inc., the Building and Construction Trades Department, 
AFL-CIO (BCTD), and the Precast/Prestressed Concrete Institute (PCI), 
strongly supported this approach (e.g., Document ID 2292, p. 3; 3587, 
Tr. 3655; 2371, Attachment 1, p. 10; 4223, p. 68; 2276, p. 10). 
However, some commenters from the construction industry, including 
CISC, Holes Incorporated, and ABC, considered a performance option to 
be unworkable in the construction industry due to variability in 
exposures (e.g., Document ID 2319, p. 85; 3580, Tr. 1448-1450; 4216, 
pp. 2-3; 2226, p. 2). SMACNA also suggested that using historical air 
monitoring data or objective data is not a legitimate option for small 
employers who do not have this type of information (Document ID 2226, 
p. 2).
    While some small businesses and construction employers, like Holes 
Incorporated, noted the difficulties with utilizing this option, there 
were other similarly situated commenters, like Arch Masonry, that felt 
the performance option was necessary to fulfill their exposure 
assessment obligations (e.g., Document ID 3580, Tr. 1448-1450; 2292, p. 
3). OSHA understands that the performance option may not be the 
preferred choice of every employer, but it expects it will provide many 
employers with substantial flexibility to meet their exposure 
assessment obligations. Thus, the Agency has included the performance 
option in the rule to complement the scheduled monitoring option.
    In addition, the restructured standard for construction provides 
added flexibility to construction employers in another significant way. 
As described in the summary and explanation of Specified Exposure 
Control Methods, where the employer fully and properly implements the 
engineering controls, work practices, and respiratory protection 
specified on Table 1 for a task, the employer is not required to assess 
the exposure of employees engaged in that task or take additional 
measures to ensure that the exposures of those employees do not exceed 
the revised PEL (see paragraph (c)(1) of the standard for 
construction). These revisions will relieve construction employers of 
the burden of performing exposure assessment in many situations and 
will provide them with greater flexibility to meet the requirements of 
the standard, while still providing construction workers with the same 
level of protection as that provided to other workers.
    The rule also includes the scheduled monitoring option in order to 
provide employers with a clearly defined, structured approach to 
assessing employee exposures. Some commenters, such as CISC and ASSE, 
urged OSHA to reconsider the inclusion of the scheduled monitoring 
option, finding it to be impractical, infeasible, and burdensome (e.g., 
Document ID 2319, p. 86; 3578, Tr. 1052). On the other hand, NISA and 
the Shipbuilders Council of America (SCA) supported the inclusion of 
both a performance option and a scheduled monitoring option for 
exposure assessment (Document ID 2195, p. 36; 2255, p. 3). AFL-CIO 
supported periodic exposure assessments when exposures are above the 
action level, with more frequent assessments required if exposures 
exceed the PEL, as required under the scheduled monitoring option. It 
also noted that similar requirements for periodic exposure assessments 
are included in all other health standards that include exposure 
monitoring and argued that they should also be included in the rule 
(Document ID 4204, pp. 53-54). As discussed below, the Agency finds 
that this option may be useful for certain employers and has retained 
it in order to maximize flexibility in the rule.

[[Page 16761]]

    General requirement for exposure assessment. Paragraph (d)(1) of 
the standard for general industry and maritime (paragraph (d)(2)(i) of 
the standard for construction) contains the general requirement for 
exposure assessment. This provision, which remains the same as proposed 
except for minor editorial changes, requires employers to assess the 
exposure of each employee who is or may reasonably be expected to be 
exposed to respirable crystalline silica at or above the action level 
of 25 [micro]g/m\3\ in accordance with either the performance option or 
the scheduled monitoring option. All employers covered by the standard 
for general industry and maritime must abide by this provision. 
However, as discussed in the summary and explanation of Specified 
Exposure Control Methods, employers following the standard for 
construction need only follow this provision, and the remainder of 
paragraph (d)(2), for tasks not listed in Table 1 or where the employer 
does not fully and properly implement the engineering controls, work 
practices, and respiratory protection described in Table 1 (see 
paragraph (d) of the standard for construction).
    OSHA received a number of comments on this general provision. For 
example, the Center for Progressive Reform (CPR) recommended that OSHA 
require employers to conduct exposure assessments for each employee who 
is or may ``foreseeably'' be exposed at or above the action level, 
rather than only for those employees ``reasonably expected'' to be 
exposed at or above the action level. They argued that ``expected'' 
exposures might be lower than ``foreseeable'' exposures, and cited 
equipment malfunctions and problems with respiratory protection 
programs as situations that are ``foreseeable'' but may not be 
``expected'' (Document ID 4005, pp. 2-4). OSHA is not persuaded by this 
argument. The Agency has decided that employers should not be required 
to conduct assessments when employee exposures are only likely to 
exceed the action level during a foreseeable, but unexpected event. 
Therefore, an employer who reasonably expects the exposure of an 
employee to remain below the action level does not have to assess the 
exposure of that employee. However, if equipment malfunctions or other 
unexpected events that could affect employee exposures occur, then the 
employer may not be able to reasonably expect employee exposure to 
remain below the action level and would be required to conduct an 
assessment. As to CPR's comment that anticipated problems with 
respiratory protection programs might be foreseeable, but unexpected, 
OSHA reminds employers that this rule defines ``employee exposure'' to 
mean exposure that would occur without the use of a respirator, so 
inadequacies in an employer's respiratory protection program do not 
affect the requirement for exposure assessment.
    OSHA also received a number of comments on whether triggering 
exposure monitoring at an action level of 25 [micro]g/m\3\ is 
appropriate. Some commenters, including the Center for Effective 
Government (CEG), APHA, NCL, and the Association of Occupational and 
Environmental Clinics (AOEC) agreed that the proposed action level 
trigger of 25 [micro]g/m\3\ for exposure assessment was needed (e.g., 
Document ID 2341, pp. 2-3; 2178, Attachment 1, p. 2; 2373, p. 2; 3399, 
p. 5). CEG argued that an action level trigger of 25 [micro]g/m\3\ is 
needed to ensure that exposures are reduced below the PEL (Document ID 
2341, p. 3). AOEC commented that this trigger is needed to help protect 
employees from crystalline silica isomorphs that are particularly toxic 
(Document ID 3399, p. 5). Dr. Franklin Mirer, Professor of 
Environmental and Occupational Health at CUNY School of Public Health, 
representing AFL-CIO, and the United Automobile, Aerospace and 
Agricultural Implement Workers of America (UAW), supported an action 
level trigger, but stated that an action level below 25 [micro]g/m\3\ 
might be necessary in order to ensure that exposures are continuously 
below the PEL (Document ID 2256, Attachment 3, p. 1; 2282, Attachment 
3, pp. 1, 14).
    Other commenters, including NISA, the Industrial Minerals 
Association--North America, the Institute of Makers of Explosives 
(IME), and the American Petroleum Institute (API), agreed that 
assessing exposures at an action level was necessary, but believed the 
action level should be 50 [micro]g/m\3\ (with a PEL of 100 [micro]g/
m\3\) (e.g., Document ID 2195, pp. 5-6; 2200, pp. 2-3; 2213, p. 3; 
2301, Attachment 1, p. 4). NISA, for example, disagreed with OSHA's 
characterization of significant risk at the proposed PEL and action 
level, but argued that an action level trigger is needed in order to 
maintain individual employees' exposures below the PEL (Document ID 
2195, p. 6). Francisco Trujillo, safety director for Miller and Long, 
proposed that exposure assessment should be triggered at an action 
level of 75 [micro]g/m\3\ (with a PEL of 100 [micro]g/m\3\) for the 
construction industry (Document ID 2345, p. 2). The American 
Exploration and Production Council (AXPC) encouraged OSHA to trigger 
all ancillary provisions in this rule (presumably including exposure 
assessment) only when exposures are at or above an action level of 50 
[micro]g/m\3\ after ``discount[ing] exposure levels to reflect the 
demonstrated effectiveness of respiratory protection . . .'' (Document 
ID 2375, Attachment 1, p. 3). The National Institute for Occupational 
Safety and Health and CPR agreed that the action level should be the 
trigger, but did not specify where the action level should be set 
(Document ID 3579, Tr. 138-139; 2351, p. 10).
    On the other hand, commenters including the Fertilizer Institute, 
NSSGA, and Acme Brick Company and others in the brick industry did not 
believe that an action level trigger for exposure assessment was 
necessary and that the PEL should be the trigger for exposure 
assessment (e.g., Document ID 2101, p. 10; 3583, Tr. 2303-2305; 2023, 
p. 6). NSSGA argued that triggering sampling at the action level is not 
sufficient to ensure compliance and instead, the individual employer 
should determine when and how much sampling should be done in order to 
ensure compliance with the PEL (Document ID 3583, Tr. 2303-2305). In 
addition, several commenters, such as Lafarge, ASA, NSSGA, AFPM, the 
Tile Council of North America (TCNA), the American Iron and Steel 
Institute, and CISC discussed the challenges of measuring exposures at 
an action level of 25 [micro]g/m\3\ (e.g., Document ID 2179, pp. 2-3; 
2187, p. 5; 2327, Attachment 1, p. 16; 2350, p. 9; 2363, p. 4; 3492, p. 
3; 2319, pp. 85-86).
    OSHA concludes that an action level trigger for exposure assessment 
is appropriate and agrees with commenters that an action level trigger 
is needed in order to maintain exposures below the PEL. An action level 
trigger, typically set at half the PEL, is consistent with other OSHA 
health standards, such as the standards for 1,3-butadiene (29 CFR 
1910.1051), methylene chloride (29 CFR 1910.1052), and chromium (VI) 
(29 CFR 1910.1026). It provides employees and employers with some 
assurance that variations in exposure levels will be accurately tracked 
and exposures above the PEL will be identified and corrective actions 
will be taken to protect employees. Assessment at the action level is 
also necessary to determine eligibility for medical surveillance in the 
standard for general industry and maritime. Where it is possible for 
employers to reduce exposures below the action level, the trigger 
encourages employers to do so in order to minimize their exposure 
assessment obligations while maximizing the protection of

[[Page 16762]]

employees' health. As discussed in Chapter IV of the Final Economic 
Analysis and Final Regulatory Flexibility Analysis (FEA), OSHA has also 
concluded that it is technologically feasible to reliably measure 
employee exposures at an action level of 25 [micro]g/m\3\.
    OSHA disagrees with AXPC's suggestion to consider the effect of 
respiratory protection when setting the exposure assessment trigger or 
when triggering other provisions in this rule. Although there may be 
some circumstances where a breathing zone sample does not reflect the 
actual exposure of an employee who is being protected by a respirator, 
this argument overlooks the fact that exposure monitoring is not a 
single purpose activity. It is necessary to know employee exposure 
levels without the use of respiratory protection to evaluate the 
effectiveness of the required engineering and work practice controls 
and to determine whether additional controls must be instituted. In 
addition, monitoring is necessary to determine which respirator, if 
any, must be used by the employee, and it is also necessary for 
compliance purposes.
    In addition, as discussed in the summary and explanation of Methods 
of Compliance, respirators will not protect employees if they are not 
fitted and maintained correctly and replaced as necessary or if 
employees do not use them consistently and properly. If any one of 
these conditions is not met, the protection a respirator provides to an 
employee can be reduced or eliminated. Thus, discounting exposure 
levels based on respirator use would be inappropriate. Moreover, the 
requirement to use respiratory protection under paragraph (f)(1) of the 
standard for general industry and maritime (paragraph (d)(3)(i) of the 
standard for construction) is triggered by employee exposures that 
exceed the PEL. It is unclear how AXPC believes the original exposure 
assessment level (to which the discount would be applied) could be 
derived without conducting an exposure assessment. Therefore, OSHA 
declines to adopt this suggestion.
    EEI urged OSHA to consider exempting intermittent and short-
duration work in the electric utility industry from the exposure 
assessment requirement where employees exposed at or above the action 
level wear appropriate personal protective equipment required under 
either 29 CFR part 1910, subpart I or 29 CFR part 1926, subpart E 
(Document ID 2357, pp. 13-14). While OSHA understands that conducting 
exposure monitoring in these situations may present challenges, it is 
important that employees who perform intermittent and short-duration 
work in the electric utility industry have their exposures assessed; 
the need for accurate information on exposures is no less for these 
employees than for other employees exposed to respirable crystalline 
silica at or above the action level. Where exposure assessments are 
required for intermittent and short-duration work, the performance 
option provides considerable flexibility for meeting these obligations. 
However, other provisions of the rule may relieve employers from 
conducting exposure assessments in some of these situations. For 
general industry and maritime, in situations where employers have 
objective data demonstrating that employee exposure will remain below 
25 [micro]g/m\3\ as an 8-hour TWA under any foreseeable conditions, 
including during intermittent and short-duration work, paragraph (a)(2) 
exempts the employer from the scope of the rule. For construction, in 
situations where employee exposure will remain below 25 [micro]g/m\3\ 
as an 8-hour TWA under any foreseeable conditions, including during 
intermittent and short-duration work, paragraph (a) exempts the 
employer from the scope of the rule. In addition, as discussed in the 
summary and explanation of Scope, where tasks performed in a general 
industry or maritime setting are indistinguishable from construction 
tasks listed on Table 1, OSHA permits employers to comply with either 
all of the provisions of the standard for general industry and maritime 
or all of the provisions of the standard for construction. When this 
occurs and the employer fully complies with the standard for 
construction, the employer will not be required to conduct exposure 
assessments for employees engaged in those tasks. Therefore, OSHA has 
concluded that a specific exemption from exposure assessment 
requirements for intermittent and short-duration work in the electric 
utility industry is neither needed nor sufficiently protective.
    As discussed above, paragraph (d)(1) of the standard for general 
industry and maritime (paragraph (d)(2)(i) of the standard for 
construction), unlike the general exposure assessment requirement in 
the proposal, provides two options for exposure assessment--a 
performance option and a scheduled monitoring option. The scheduled 
monitoring option provides a framework that is familiar to many 
employers, and has been successfully applied in the past. The 
performance option provides flexibility for employers who are able to 
characterize employee exposures through alternative methods. In either 
case, employers must assess the exposure of each employee who is or may 
reasonably be expected to be exposed to respirable crystalline silica 
at or above the action level.
    The performance option. Paragraph (d)(2) of the standard for 
general industry and maritime (paragraph (d)(2)(ii) of the standard for 
construction) describes the performance option. This option provides 
employers flexibility to assess the 8-hour TWA exposure for each 
employee on the basis of any combination of air monitoring data or 
objective data sufficient to accurately characterize employee exposures 
to respirable crystalline silica. OSHA recognizes that exposure 
monitoring may present challenges in certain instances, particularly 
when tasks are of short duration or performed under varying 
environmental conditions. The performance option is intended to allow 
employers flexibility in assessing the respirable crystalline silica 
exposures of their employees.
    Where the employer elects this option, the employer must conduct 
the exposure assessment prior to the time the work commences, and must 
demonstrate that employee exposures have been accurately characterized. 
To accurately characterize employee exposures under the performance 
option, the assessment must reflect the exposures of employees on each 
shift, for each job classification, in each work area. However, under 
this option, the employer has flexibility to determine how to achieve 
this. For example, under this option an employer could determine that 
there are no differences between the exposure of an employee in a 
certain job classification who performs a task in a particular work 
area on one shift and the exposure of another employee in the same job 
classification who performs the same task in the same work area on 
another shift. In that case, the employer could characterize the 
exposure of the second employee based on the characterization of the 
first employee's exposure.
    Accurately characterizing employee exposures under the performance 
option is also an ongoing duty. In order for exposures to continue to 
be accurately characterized, the employer is required to reassess 
exposures whenever a change in production, process, control equipment, 
personnel, or work practices may reasonably be expected to result in 
new or additional exposures at or above the action level, or when the 
employer has any reason to believe that new or additional exposures at 
or above the action level have occurred (see discussion below of 
paragraph (d)(4) of

[[Page 16763]]

the standard for general industry and maritime and paragraph (d)(2)(iv) 
of the standard for construction).
    When using the performance option, the burden is on the employer to 
demonstrate that the data accurately characterize employee exposure. 
However, the employer can characterize employee exposure within a 
range, in order to account for variability in exposures. For example, a 
general industry or maritime employer could use the performance option 
and determine that an employee's exposure is between the action level 
and the PEL. Based on this exposure assessment, the employer would be 
required under paragraph (i)(1)(i) to provide medical surveillance if 
the employee is exposed for more than 30 days per year. Where an 
employer uses the performance option and finds exposures to be above 
the PEL after implementing all feasible controls, the employer would be 
required to provide the appropriate level of respiratory protection. 
For example, an employer who has implemented all feasible controls 
could use the performance option to determine that exposures exceed the 
PEL, but do not exceed 10 times the PEL. The employer would be required 
under paragraph (g) of the standard for general industry and maritime 
(paragraph (e) of the standard for construction) to provide respiratory 
protection with an assigned protection factor of at least 10, as well 
as medical surveillance for employees exposed for more than 30 days per 
year.
    Several commenters requested that OSHA provide more guidance as to 
how employers should implement the performance option. Commenters, 
including AFL-CIO, the International Union of Bricklayers and Allied 
Craftworkers (BAC), the United Steelworkers, BCTD, and the 
International Union of Operating Engineers (IUOE), felt that 
clarification and guidance on the kind of data that may or may not be 
relied upon was needed in order to ensure that the data adequately 
reflected employee exposures (Document ID 2256, Attachment 2, p. 10; 
2329, p. 4; 2336, p. 6; 2371, Attachment 1, pp. 11-13; 3581, Tr. 1693-
1694; 3583, Tr. 2341; 4204, p. 54; 4223, p. 70). The American College 
of Occupational and Environmental Medicine recommended that OSHA more 
precisely specify the type and periodicity of collection of industrial 
hygiene data that would be required to assure representative exposure 
measurements (Document ID 2080, p. 4). The American Industrial Hygiene 
Association (AIHA) argued that a sufficient number of samples and a 
sampling strategy that is representative of the employees and tasks 
being sampled is needed to ensure that exposure assessments using the 
performance option accurately characterize employee exposure (Document 
ID 3578, Tr. 1049-1050). To do this, AIHA suggested that OSHA,

. . . point to American Industrial Hygiene Association language on 
what an acceptable judgment of exposure can be based upon: number of 
samples for statistical validity, an acceptable tolerance for an 
error in that statistical judgment, and the connection of the sample 
set to a set of conditions occurring during the worker exposure 
measurement (Document ID 2169, p. 3).

    CISC also indicated that the construction industry needed 
additional guidance, such as how often and when monitoring should be 
conducted under the performance option in order to determine whether it 
would be effective and viable (Document ID 2319, p. 86). Charles 
Gordon, a retired occupational safety and health attorney, suggested 
the performance option was too flexible and needed to be omitted until 
real-time monitoring could be incorporated into it (Document ID 2163, 
Attachment 1, p. 17).
    OSHA has not included specific criteria for implementing the 
performance option in the rule. Since the goal of the performance 
option is to give employers flexibility to accurately characterize 
employee exposures using whatever combination of air monitoring data or 
objective data is most appropriate for their circumstances, OSHA 
concludes it would be inconsistent to specify in the standard exactly 
how and when data should be collected. Where employers want a more 
structured approach for meeting their exposure assessment obligations, 
OSHA also provides the scheduled monitoring option.
    OSHA does, however, offer two clarifying points. First, the Agency 
clarifies that when using the term ``air monitoring data'' in this 
paragraph, OSHA refers to any monitoring conducted by the employer to 
comply with the requirements of this standard, including the prescribed 
accuracy and confidence requirements. Second, the term does not include 
historic air monitoring data, which are ``objective data.'' Additional 
discussion of the types of data and exposure assessment strategies that 
may be used by employers as ``objective data'' to accurately 
characterize employee exposures to respirable crystalline silica can be 
found in the summary and explanation of Definitions.
    For example, trade associations and other organizations could 
develop objective data based on industry-wide surveys that members 
could use to characterize employee exposures to respirable crystalline 
silica. For example, the National Automobile Dealers Association (NADA) 
conducted air monitoring for employees performing a variety of tasks in 
automobile body shops (Document ID 4197; 4198). NADA worked to ensure 
that the results of the study were representative of typical 
operations. The sampling procedures and techniques for controlling dust 
were documented. These data may allow body shops that perform tasks in 
a manner consistent with that described in the NADA survey to rely on 
this objective data to characterize employee exposures to respirable 
crystalline silica.
    Employers could also use portable, direct-reading instruments to 
accurately characterize employee exposures to respirable crystalline 
silica. These devices measure all respirable dusts, not only 
crystalline silica. But where the employer is aware of the proportion 
of crystalline silica in the dust, direct-reading instruments have the 
advantage of providing real-time monitoring results. For example, in a 
facility using pure crystalline silica, the employer could assume that 
the respirable crystalline silica concentration in the air is 
equivalent to the respirable dust measurement provided by the direct 
reading instrument. Where exposures involve dusts that are not pure 
crystalline silica, the employer could determine the concentration of 
crystalline silica by analysis of bulk samples (e.g., geotechnical 
profiling) or information on safety data sheets, and calculate the air 
concentration accordingly. In such situations, the analysis of bulk 
samples or safety data sheets would be part of the objective data 
relied on by the employer. In addition, employers could use a wide 
variety of other types of objective data to assess exposures, including 
data developed using area sampling or area exposure profile mapping 
approaches. Where new methods become available in the future that 
accurately characterize employee exposure to respirable crystalline 
silica, data generated using those methods could also be considered 
objective data and could be used by employers to assess employee 
exposures.
    Where employers rely on objective data generated by others as an 
alternative to developing their own air monitoring data, they will be 
responsible for ensuring that the data relied upon from other sources 
are accurate measures of their employees' exposures. Thus, the burden 
is on the

[[Page 16764]]

employer to show that the exposure assessment is sufficient to 
accurately characterize employee exposures to respirable crystalline 
silica.
    CPR suggested that OSHA require an independent audit of employers' 
objective data calculations to ensure that they provide the same degree 
of assurance of accurate exposure characterization as air monitoring 
data (Document ID 2351, pp. 12-13). As explained above, employers using 
the performance option must ensure that the exposure assessment is 
sufficient to accurately characterize employee exposure to respirable 
crystalline silica. Because employers already bear the burden of 
ensuring accurate characterization of employee exposures, OSHA does not 
find that an independent audit of employers' objective data is 
necessary to assure proper compliance.
    The Laborers' Health and Safety Fund of North America urged OSHA to 
collect and post all objective data that meet the definition on its Web 
site, so that it could be used by anyone performing the same task under 
the same conditions (Document ID 2253, p. 4). Other commenters, 
including BAC, BCTD, and IUOE, agreed that developing a means for 
collecting and sharing objective data was important (Document ID 2329, 
p. 4; 2371, Attachment 1, p. 13; 3583, Tr. 2394-2395). OSHA recognizes 
that the collection and sharing of objective data can be a useful tool 
for employers characterizing exposures using the performance option. 
OSHA anticipates that there could be a substantial volume of objective 
data that would require significant resources to collect, organize, 
present, and maintain in a way that is accessible, understandable, and 
valuable to employers. The Agency does not have the resources to do 
this; however, employers, professional and trade associations, unions, 
and others that generate objective data are encouraged to aggregate and 
disseminate this type of information.
    As with the standard for chromium (VI), 29 CFR 1910.1026, OSHA does 
not limit when objective data can be used to characterize exposure. 
OSHA permits employers to rely on objective data for meeting their 
exposure assessment obligations, even where exposures may exceed the 
action level or PEL. OSHA's intent is to allow employers flexibility to 
assess employee exposures to respirable crystalline silica, but to 
ensure that the data used are accurate in characterizing employee 
exposures. For example, where an employer has a substantial body of 
data (from previous monitoring, industry-wide surveys, or other 
sources) indicating that employee exposures in a given task exceed the 
PEL, the employer may choose to rely on those data to determine his or 
her compliance obligations (e.g., implementation of feasible 
engineering and work practice controls, respiratory protection, medical 
surveillance).
    OSHA has also not established time limitations for air monitoring 
results used to characterize employee exposures under the performance 
option. Although the proposed standard would have limited employers 
using air monitoring data for initial exposure assessment purposes to 
data collected no more than twelve months prior to the rule's effective 
date, there were no such time restrictions on monitoring data used to 
conduct periodic exposure assessments under the performance option. 
Nevertheless, many commenters, including Ameren, TCNA, NAM, NAIMA, 
Associated General Contractors of New York State, ARMA, EEI, the 
National Rural Electric Cooperative Association, the Glass Packaging 
Institute, Verallia North America, and Holes Incorporated, found the 
12-month limit on the use of monitoring results for initial exposure 
assessments using existing data to be too restrictive (e.g., Document 
ID 2315, p. 3; 2363, p. 6; 2380, Attachment 2, pp. 28-29; 3544, pp. 12-
13; 2145, p. 3; 2291, pp. 2, 21-23; 2348, pp. 37-39; 2357, pp. 22-23; 
2365, pp. 10-11, 23; 2290, p. 4; 3493, p. 6; 3584, Tr. 2848; 3580, Tr. 
1492). For example, Southern Company noted that:

    We have been collecting data on silica for several years as well 
as sharing within our industry group. This provision seems to be 
arbitrary and provides only a short window of time for data 
collection while eliminating the value and importance of past 
[efforts] we have placed on this issue (Document ID 2185, p. 7).

    OSHA has been persuaded by these commenters not to establish time 
limitations for monitoring results used to assess exposures under the 
performance option, as long as the employer can demonstrate the data 
accurately characterize current employee exposures to respirable 
crystalline silica. The general principle that the burden is on the 
employer to show that the data accurately characterize employee 
exposure to respirable crystalline silica applies to the age of the 
data as well as to the source of the data. For example, monitoring 
results obtained 18 months prior to the effective date of the standard 
could be used to determine employee exposures, but only if the employer 
could show that the data were obtained during work operations conducted 
under workplace conditions closely resembling the processes, types of 
material, control methods, work practices, and environmental conditions 
in the employer's current operations. Regardless of when they were 
collected, the data must accurately reflect current conditions.
    Any air monitoring data relied upon by employers must be maintained 
and made available in accordance with the recordkeeping requirements in 
paragraph (k)(1) of the standard for general industry and maritime 
(paragraph (j)(1) of the standard for construction). Any objective data 
relied upon must be maintained and made available in accordance with 
the recordkeeping requirements in paragraph (k)(2) of the standard for 
general industry and maritime (paragraph (j)(2) of the standard for 
construction).
    NISA commented that a performance option needs to be consistently 
interpreted by compliance officers in order for such an approach to be 
truly useful to employers (Document ID 2195, p. 36). OSHA agrees. OSHA 
regularly establishes policies and directives to guide compliance 
officers in a uniform, consistent manner when enforcing standards. 
These policies ensure that all the provisions of OSHA standards, 
including performance options, are consistently applied in the field.
    The scheduled monitoring option. Paragraph (d)(3) of the standard 
for general industry and maritime (paragraph (d)(2)(iii) of the 
standard for construction) describes the scheduled monitoring option. 
This option provides employers with a clearly defined, structured 
approach to assessing employee exposures. Under paragraph (d)(3)(i) of 
the standard for general industry and maritime (paragraph 
(d)(2)(iii)(A) of the standard for construction), employers who select 
the scheduled monitoring option must conduct initial monitoring to 
determine employee exposure to respirable crystalline silica. 
Monitoring to determine employee exposures must represent the 
employee's time-weighted average exposure to respirable crystalline 
silica over an eight-hour workday. Samples must be taken within the 
employee's breathing zone (i.e., ``personal breathing zone samples'' or 
``personal samples''), and must represent the employee's exposure 
without regard to the use of respiratory protection. OSHA intends for 
employers using the scheduled monitoring option to conduct initial 
monitoring as soon as work begins. Employers must be aware of the level 
of exposure when work is performed to identify situations where control 
measures are needed.

[[Page 16765]]

    Under the scheduled monitoring option, just as under the 
performance option, employers must accurately characterize the exposure 
of each employee to respirable crystalline silica. In some cases, this 
will entail monitoring all exposed employees. In other cases, 
monitoring of ``representative'' employees is sufficient. 
Representative exposure sampling is permitted when several employees 
perform essentially the same job on the same shift and under the same 
conditions. For such situations, it may be sufficient to monitor a 
subset of these employees in order to obtain data that are 
``representative'' of the remaining employees. Representative personal 
sampling for employees engaged in similar work, with respirable 
crystalline silica exposure of similar duration and magnitude, is 
achieved by monitoring the employee(s) reasonably expected to have the 
highest respirable crystalline silica exposures. For example, this 
could involve monitoring the respirable crystalline silica exposure of 
the employee closest to an exposure source. The exposure result may 
then be attributed to other employees in the group who perform the same 
tasks on the same shift and in the same work area.
    Exposure monitoring should include, at a minimum, one full-shift 
sample taken for each job function in each job classification, in each 
work area, for each shift. These samples must consist of at least one 
sample characteristic of the entire shift or consecutive representative 
samples taken over the length of the shift. Where employees are not 
performing the same job under the same conditions, representative 
sampling will not adequately characterize actual exposures, and 
individual monitoring is necessary.
    Stakeholders offered numerous comments and suggestions about the 
proposed provisions that would have required employers to assess 
employee exposure on the basis of personal breathing zone air samples 
that reflect the exposure of employees on each shift, for each job 
classification, and in each work area. Many of these comments and 
suggestions involved specific concerns with the practicality and 
necessity of assessing employee exposure on each shift, for each job 
classification, and in each work area (e.g., Document ID 2315, p. 3; 
2317, p. 2; 2215, p. 9; 2312, p. 2; 2348, Attachment 1, p. 39; 2357, p. 
23; 2327, Attachment 1, p. 18; 2380, Attachment 2, pp. 26-28; 2179, p. 
3; 2291, pp. 20-21). As discussed previously, OSHA responded to these 
comments by restructuring the exposure assessment requirements to allow 
employers to use the performance option for all exposure assessments 
required by this rule. Although employers utilizing the performance 
option must still accurately characterize the exposures of each of 
their employees, these employers have latitude to broadly consider the 
best way this can be accomplished.
    NAIMA suggested that OSHA should make adjustments to exposure 
monitoring requirements for extended work shifts (e.g., 12-hour 
shifts). They proposed that

. . . exposure assessment should follow the standard practice of 
measuring any continuous 8-hour period in the shift that is 
representative, or allow using multiple samples to sample the entire 
extended shift and selecting the 8 hours which represent the highest 
potential exposure (Document ID 3544, p. 14).

    OSHA agrees that this is an appropriate way to conduct sampling for 
extended work shifts. This practice is already reflected in the OSHA 
Technical Manual, which describes the two approaches advanced by NAIMA, 
including sampling the worst (highest exposure) eight hours of a shift 
or collecting multiple samples over the entire work shift and using the 
highest samples to calculate an 8-hour TWA (OSHA Technical Manual, 
Section II, Chapter 1, 2014, https://www.osha.gov/dts/osta/otm/otm_ii/otm_ii_1.html#extended_workshifts).
    CISC argued that the ASTM Standard E 2625-09, Standard Practice for 
Controlling Occupational Exposure to Respirable Crystalline Silica for 
Construction and Demolition Activities, takes what CISC considered to 
be a more reasonable approach to representative air monitoring in the 
construction industry. The ASTM standard states that measurements 
``need to be representative of the worker's customary activity and be 
representative of work shift exposure'' (Document ID 1504). CISC argued 
that this approach is,

. . . more reasonable because it inherently recognizes that an 
employee's exposure would vary on any given day due to a multitude 
of factors and that an employer should attempt to understand the 
exposure levels when performing his/her customary activity (Document 
ID 2319, pp. 83-84).

    OSHA acknowledges that variability in exposures is a concern in the 
construction industry. The construction standard does not require 
exposure assessment for employees engaged in a task identified on Table 
1 where the employer fully and properly implements the specified 
exposure control methods presented on Table 1 (see paragraph (c) of the 
standard for construction). As noted above, the performance option, in 
paragraph (d)(2) of the standard for general industry and maritime 
(paragraph (d)(2)(ii) of the standard for construction), also provides 
flexibility to characterize employee exposures in a manner that 
accounts for variability, in that it allows exposures to be assessed 
using any combination of air monitoring data and objective data. But 
OSHA does not consider that it is appropriate to allow exposure 
assessment to include only an employee's ``customary activity,'' 
because such an approach would ignore activities that may involve 
higher exposures to respirable crystalline silica, and the higher 
levels of risk associated with those exposures.
    Under the scheduled monitoring option, requirements for periodic 
monitoring depend on the results of initial monitoring and, thereafter, 
any required subsequent monitoring. Paragraphs (d)(3)(ii)-(iv) of the 
standard for general industry and maritime (paragraphs (d)(2)(iii)(B)-
(D) of the standard for construction) describe the employers' duties 
depending on the initial (and, after that, the most recent) monitoring 
results. If the initial monitoring indicates that employee exposures 
are below the action level, no further monitoring is required. If the 
most recent exposure monitoring reveals employee exposures to be at or 
above the action level but at or below the PEL, the employer must 
repeat monitoring within six months of the most recent monitoring. If 
the most recent exposure monitoring reveals employee exposures to be 
above the PEL, the employer must repeat monitoring within three months 
of the most recent monitoring.
    Paragraph (d)(3)(v) of the standard for general industry and 
maritime (paragraph (d)(2)(iii)(E) of the standard for construction) 
provides that if the most recent (non-initial) exposure monitoring 
indicates that employee exposures are below the action level, and those 
results are confirmed within six months of the most recent monitoring 
by a second measurement taken consecutively at least seven days 
afterwards, the employer may discontinue monitoring for those employees 
whose exposures are represented by such monitoring. As discussed below, 
reassessment is always required whenever a change in the workplace may 
be reasonably expected to result in new or additional exposures at or 
above the action level or the employer has any reason to believe that 
new or additional exposures at or above the action level have occurred, 
regardless of whether the employer has ceased monitoring because 
exposures are below the action level under

[[Page 16766]]

paragraph (d)(3)(ii) or (d)(3)(v) of the standard for general industry 
and maritime (paragraph (d)(2)(iii)(B) or (d)(2)(iii)(E) of the 
standard for construction) (see paragraph (d)(4) of the standard for 
general industry and maritime (paragraph (d)(2)(iv) of the standard for 
construction)).
    OSHA made a number of minor changes to the requirements for 
periodic monitoring under the scheduled monitoring option from the 
proposal based on stakeholder comments. For example, paragraph 
(d)(3)(i)(B) of the proposed regulatory text provided that ``[w]here 
initial or subsequent exposure monitoring reveals that employee 
exposures are above the PEL, the employer shall repeat such monitoring 
at least every three months.'' Subparagraph (C) then stated: ``the 
employer shall continue monitoring at the required frequency until at 
least two consecutive measurements, taken at least 7 days apart, are 
below the action level, at which time the employer may discontinue 
monitoring . . .''
    ARMA argued that these provisions were confusing and ``might be 
interpreted to require employers to continue monitoring quarterly, even 
if two consecutive measurements are at or above the action level but at 
or below the PEL''--a reading that ARMA believed conflicted with the 
language of paragraph (d)(3)(i)(A), which provided that ``[w]here 
initial or subsequent exposure monitoring reveals that employee 
exposures are at or above the action level but at or below the PEL, the 
employer shall repeat such monitoring at least every six months'' 
(Document ID 2291, p. 23). ARMA added that it anticipated that OSHA 
intended these provisions to impose the same periodic monitoring 
requirements that appear routinely in other OSHA health standards. It 
explained: ``[u]nder that approach, even if periodic monitoring must be 
conducted quarterly because the initial (or subsequent) assessment 
shows exposures in excess of the PEL, the frequency can be reduced to 
quarterly once two consecutive measurements more than seven days apart 
fall below the PEL but above the action level'' (Document ID 2291, p. 
23).
    OSHA agrees with ARMA's comment and has revised the periodic 
monitoring provisions under the scheduled monitoring option to better 
reflect OSHA's intent--as a general rule, the most recent exposure 
monitoring sample determines how often an employer must monitor. OSHA 
has also revised proposed paragraph (d)(3)(i)(C) to clarify the 
circumstances under which employers who choose the scheduled monitoring 
option may discontinue periodic monitoring.
    Stakeholders also commented on how often employers should be 
required to conduct exposure monitoring. Several commenters, including 
the National Tile Contractors Association (NTCA), Dal-Tile, Grede 
Holdings, ORCHSE Strategies (ORCHSE), Benton Foundry, PCI, TCNA, and 
NISA, disagreed with the proposed frequency of monitoring and suggested 
other frequencies (every 6 months, 12 months, 18 months, or as 
determined by a competent person) (e.g., Document ID 2267, p. 7; 2147, 
p. 3; 2298, p. 4; 2277, p. 3; 1972, p. 2; 2276, p. 6; 3584, Tr. 2744; 
2363, p. 7; 2195, p. 36). IUOE and EEI, among others, suggested that 
the three or six-month intervals for follow-up exposure assessment will 
do nothing to protect employees on jobs of short duration (e.g., 
Document ID 2262, p. 11; 2357, p. 31). AFS suggested that a scheduled 
monitoring option ``that includes quarterly and semi-annual monitoring 
does not gather useful information and is punitive in intent'' 
(Document ID 2379, Appendix 1, p. 55). EEI urged OSHA to revise the 
scheduled monitoring option to either:

. . . (a) permit employers to conduct subsequent exposure 
assessments without an arbitrary timetable of three or six months; 
(b) permit employers to conduct subsequent exposure assessments in 
longer, more reasonable intervals, such as annually or biennially; 
or (c) create an exception to periodic exposure assessment 
requirement when no changes in the workplace, control equipment, or 
work practices have occurred (Document ID 2357, p. 21).

    Francisco Trujillo, representing Miller and Long, proposed that 
where exposures were between the action level and the PEL, exposure 
assessment be required at least every six months unless employers 
implement the same controls used to control exposures above the PEL 
(Document ID 2345, p. 3). OSHA recognizes that exposures in the 
workplace may fluctuate. Periodic monitoring, however, is intended to 
provide the employer with reasonable assurance the employees are not 
experiencing exposures that are higher than the PEL and require the use 
of additional control measures. If the employer installs or upgrades 
controls, periodic monitoring will demonstrate whether or not controls 
are working properly or if additional controls are needed. In addition, 
periodic monitoring reminds employees and employers of the continued 
need to protect against the hazards associated with exposure to 
respirable crystalline silica. Because of the fluctuation in exposures, 
OSHA finds that when initial monitoring results equal or exceed the 
action level, but are at or below the PEL, employers must continue to 
monitor employees to ensure that exposures remain at or below the PEL. 
Likewise, when initial monitoring results exceed the PEL, periodic 
monitoring allows the employer to maintain an accurate profile of 
employee exposures. Selection of appropriate respiratory protection 
also depends on adequate knowledge of employee exposures.
    In general, the more frequently periodic monitoring is performed, 
the more accurate the employee exposure profile. Selecting an 
appropriate interval between measurements is a matter of judgment. OSHA 
concludes that the frequencies of six months for subsequent periodic 
monitoring for exposures in between the action level and the PEL, and 
three months for exposures above the PEL, provide intervals that are 
both practical for employers and protective for employees. This finding 
is supported by OSHA's experience with comparable monitoring intervals 
in other standards, including those for chromium (VI) (1910.1026), 
cadmium (29 CFR 1910.1027), methylenedianiline (29 CFR 1910.1050), 
methylene chloride (29 CFR 1910.1052), and formaldehyde (29 CFR 
1910.1048). Where employers find that a different frequency of 
monitoring is sufficient to accurately characterize employee exposure 
to respirable crystalline silica, they can use that air monitoring data 
to meet their exposure assessment obligations under the performance 
option.
    Commenters, including National Electrical Carbon Products, Lapp 
Insulators, the Indiana Manufacturers Association, ORCHSE, Murray 
Energy Corporation, the Motor and Equipment Manufacturers Association, 
IME, PCI, and NAM, urged OSHA to permit employers to cease monitoring 
or monitor on a reduced schedule when it has been determined it is 
infeasible to reduce exposures below the PEL using engineering and work 
practice controls (e.g., Document ID 1785, p. 5; 2130, p. 2; 2151, p. 
2; 2277, p. 3; 2102, p. 2; 2326, pp. 2-3; 2213, p. 4; 2276, p. 6; 2380, 
Attachment 2, pp. 29-30). OSHA concludes, however, that periodic air 
monitoring serves as a useful tool for evaluating the continuing 
effectiveness of engineering and work practice controls, and can assist 
employers in ensuring that they have met their obligation to use all 
feasible controls to limit employee exposures to the PEL. Nevertheless, 
an employer may decide that continued monitoring does not serve to 
better characterize employee exposure. In these cases, as long as the

[[Page 16767]]

air monitoring data continue to accurately characterize employee 
exposure, employers can use the existing data to meet their exposure 
assessment obligations under the performance option without conducting 
additional monitoring.
    Reassessment of exposures. Paragraph (d)(4) of the standard for 
general industry and maritime (paragraph (d)(2)(iv) of the standard for 
construction) requires employers assessing exposures using either the 
performance option or the scheduled monitoring option to reassess 
employee exposures whenever there has been a change in the production, 
process, control equipment, personnel, or work practices that may 
reasonably be expected to result in new or additional exposures to 
respirable crystalline silica at or above the action level, or when the 
employer has any reason to believe that new or additional exposures at 
or above the action level have occurred. For example, if an employer 
has conducted monitoring while a task is performed using local exhaust 
ventilation and the flow rate of the ventilation system is decreased, 
additional monitoring would be necessary to assess employee exposures 
under the modified conditions. In addition, there may be other 
situations that can result in new or additional exposures to respirable 
crystalline silica that are unique to an employee's work situation. 
OSHA inserted the phrase ``or when the employer has any reason to 
believe that new or additional exposures at or above the action level 
have occurred'' in the rule to make clear that reassessment of 
exposures is required whenever there is reason to believe that a change 
in circumstances could result in new or additional exposures at or 
above the action level. For instance, an employee may move from an 
open, outdoor location to an enclosed or confined space. Even though 
the task performed and the materials used may remain constant, the 
changed environment could reasonably be expected to result in higher 
exposures to respirable crystalline silica. In order to account for 
these situations, the rule requires employers to reassess employee 
exposures whenever a change may result in new or additional exposures 
at or above the action level. OSHA considers this reevaluation 
necessary to ensure that the exposure assessment accurately represents 
existing exposure conditions. The exposure information gained from such 
assessments will enable the employer to take appropriate action to 
protect exposed employees, such as instituting additional engineering 
controls or providing appropriate respiratory protection.
    Some commenters, including Southern Company, EEI, API, and AFPM, 
raised concerns about the requirement to conduct additional exposure 
assessments (e.g., Document ID 2185, p. 7; 2357, pp. 21-22; 2301, 
Attachment 1, p. 80; 2350, p. 10). Southern Company commented that 
employers should not have to reassess exposures for every personnel 
change, but rather only those changes that result in significant 
changes in employee exposure (Document ID 2185, p. 7). EEI urged OSHA 
to clarify what kind of change could trigger additional assessments 
(Document ID 2357, pp. 21-22). API presented concerns that this 
requirement could be interpreted to require additional assessments at 
unworkably frequent intervals (Document ID 2301, Attachment 1, p. 80). 
AFPM argued that the provision would require its members to conduct 
continuous monitoring given the requirement to reassess every time 
there is an environmental shift that would result in a new respirable 
crystalline silica level (Document ID 2350, p. 10).
    As described above, the requirement to reassess exposures only 
applies where there are changes in the workplace that may reasonably be 
expected to result in new or additional exposures at or above the 
action level or when the employer has any reason to believe that new or 
additional exposures at or above the action level have occurred. OSHA 
does not intend for employers to conduct additional monitoring simply 
because a change has occurred, so long as the change is not reasonably 
expected to result in new or additional exposures to respirable 
crystalline silica at or above the action level. Thus, in some of the 
situations highlighted by the commenters, employers may not need to 
reassess exposures. For example, where a personnel change does not have 
an expected impact on the magnitude of employee exposure to respirable 
crystalline silica, the employer would not have to reassess exposures. 
When the environmental conditions on a construction site change in ways 
that would not result in new or additional exposures at or above the 
action level, such as a change from dry, dusty conditions to wet, rainy 
conditions, the employer would not have to reassess exposures. Other 
changes that would be reasonably expected to lower exposures to 
respirable crystalline silica, rather than result in new or additional 
exposures at or above the action level, such as moving from an indoor 
to an outdoor location or using a product with a lower silica content 
than that previously used in the same process, would not require the 
employer to reassess exposures.
    Methods of sample analysis. Paragraph (d)(5) of the standard for 
general industry and maritime (paragraph (d)(2)(v) of the standard for 
construction) requires employers to ensure that all samples taken to 
satisfy the monitoring requirements are evaluated in accordance with 
Appendix A, which contains specifications for the methods to be used 
for analysis of respirable crystalline silica samples. The proposed 
provision would also have required employers to ensure that all samples 
taken to satisfy the air monitoring requirements in the exposure 
assessment paragraph were evaluated using the procedures specified in 
certain analytical methods. However, in the proposal, the analytical 
methods were laid out in paragraph (d), rather than in a separate 
Appendix.
    Several commenters, including the Korte Company, AFS, TCNA, and NAM 
expressed concerns that the proposal placed responsibility for 
laboratory performance on the employers, who are not in a position to 
ensure that laboratories are complying with specific analytical 
requirements (e.g., Document ID 3230, p. 1; 2379, Appendix 1, p. 56; 
2363, p. 7; 2380, Attachment 2, p. 31). OSHA does not expect employers 
to oversee laboratory practices. An employer who engages an independent 
laboratory to analyze respirable crystalline silica samples can rely on 
a statement from that laboratory confirming that the specifications in 
Appendix A were met.
    One stakeholder, Southern Company, recommended that OSHA require 
use of accredited laboratories and move all other laboratory 
requirements to an appendix as a guide for laboratories that analyze 
silica samples (Document ID 2185, p. 7). OSHA agrees with this 
suggestion and has decided to retain the substance of the proposed 
provisions addressing analysis of samples, but has moved these 
provisions to a new appendix. The Agency concludes that segregating 
these requirements in an appendix to each standard provides greater 
clarity for both employers and the laboratories that analyze samples. 
The specifications contained in Appendix A are discussed in the summary 
and explanation of Appendix A in this section.
    Commenters, including NSSGA, SCA, OSCO Industries, ORCHSE, 
Associated General Contractors of Michigan (AGCM), and PCI expressed 
concern about the availability of a sufficient number of qualified 
laboratories capable

[[Page 16768]]

of analyzing the increased number of air samples expected given the 
standard's exposure assessment requirements (e.g., Document ID 1992, p. 
12; 2255, p. 1; 2265, Attachment 1, p. 2; 2277, p. 3; 2327, Attachment 
1, pp. 4-6; 3589, Tr. 4357). There are approximately 40 laboratories 
that are accredited by AIHA Laboratory Accreditation Programs for the 
analysis of crystalline silica; these laboratories are already capable 
of analyzing samples in accordance with the laboratory requirements of 
this rule (Document ID 3586, Tr. 3284). While the number of accredited 
laboratories for the analysis of crystalline silica has declined over 
the last 10 or 20 years, William Walsh, the Vice Chair of the 
Analytical Accreditation Board of the AIHA Laboratory Accreditation 
Programs, testified that there is still sufficient capacity available 
to analyze crystalline silica samples and, in fact, ``each lab's 
capacity has gone up'' due to increased efficiency in the sample 
analysis process (Document ID 3586, Tr. 3311).
    OSHA expects that the additional demand for respirable crystalline 
silica exposure monitoring and associated laboratory analysis with the 
rule will be modest. Most construction employers are expected to 
implement the specified exposure control measures in paragraph (c) of 
the standard for construction, and will therefore not be required to 
conduct exposure monitoring. The performance option for exposure 
assessment provided in both the standard for general industry and 
maritime at paragraph (d)(2) and the standard for construction at 
paragraph (d)(2)(ii) also serves to lessen the future volume of 
exposure monitoring and associated laboratory analysis for crystalline 
silica. As discussed in the summary and explanation of Dates, the time 
allowed for compliance with the standard for general industry and 
maritime also serves to diminish concerns about laboratory capacity by 
providing additional time for laboratory capacity to increase and 
distributing demand for sample analysis over an extended period of 
time.
    Employee notification of assessment results. Paragraph (d)(6) of 
the standard for general industry and maritime (paragraph (d)(2)(vi) of 
the standard for construction) contains the requirements for employee 
notification of assessment results and corrective actions. Under 
paragraph (d)(6)(i) of the standard for general industry and maritime, 
employers must notify each affected employee of the results of the 
exposure assessment within 15 working days of completing the 
assessment. Paragraph (d)(2)(vi)(A) of the standard for construction 
requires this notification not more than five working days after the 
exposure assessment has been completed. Notification is required under 
both standards whenever an exposure assessment has been conducted, 
regardless of whether or not employee exposure exceeds the action level 
or PEL. Employers must either notify each individual employee in 
writing or post the assessment results in an appropriate location 
accessible to all affected employees. The term ``affected'' as used 
here means all employees for which an exposure assessment has been 
conducted, either individually or as part of a representative 
monitoring strategy. It includes employees whose exposure was assessed 
based on other employees who were sampled, and employees whose 
exposures have been assessed on the basis of objective data. As 
discussed with regard to the performance option, exposures can be 
characterized as a range, e.g., below the action level or between the 
action level and the PEL. The employer is notifying employees of 
employee exposures, i.e., exposures that would occur if the employee 
were not using a respirator. Any engineering and work practice controls 
used would be reflected in the assessment results.
    The provisions in the rule are identical to the proposed provisions 
for both general industry and maritime and construction. A number of 
commenters offered opinions on these provisions. For example, some 
commenters, including Southern Company and EEI, objected to the 
differences between the general industry and construction notification 
requirements. These stakeholders argued that establishing different 
reporting requirements for general industry and construction (i.e., 
requiring notification within 5 working days in construction and 15 
working days in general industry), would create confusion and make 
compliance difficult to achieve, especially for employers with blended 
general industry/construction operations, such as electric utilities 
(Document ID 2185, p. 4; 2357, p. 23). EEI urged OSHA to harmonize the 
requirements or clarify which section applies to the situation with 
blended general industry/construction operations (Document ID 2357, p. 
23).
    This issue is not unique to this rulemaking. In October 2002, OSHA 
published the second phase of its Standard Improvement Project (SIPS), 
which proposed to revise a number of health provisions in its standards 
for general industry, shipyard employment, and construction. The 
proposal was part of OSHA's effort to continue to remove and revise 
provisions of its standards that are outdated, duplicative, 
unnecessary, or inconsistent. One of the issues OSHA examined in Phase 
II of SIPS was the ``variety of different time limits between receipt 
of employees' exposure monitoring results and notification of 
employees'' in OSHA's substance specific standards. After a thorough 
review of the record, OSHA adopted a 15-day notification period for 
general industry and a 5-day period in construction. The Agency 
explained that its decision to set two different time frames was due, 
in part, to the general differences in the industries, i.e., general 
industry on average has ``a more stable workforce,'' while 
``[e]mployment at a particular location is often brief in construction 
. . .'' (70 FR 1112, 1126 (1/5/05)).
    Some stakeholders from the construction industry, including CISC 
and ASA, were concerned that they could not comply with the proposed 
five-day notification requirement due to the often short duration of 
tasks and employment in this sector. They argued that employers and 
employees will frequently have moved to a different job before the 
results are available, making it difficult or impossible to reach 
affected employees and rendering the data irrelevant to the new project 
with varying conditions and circumstances (e.g., Document ID 2319, p. 
87; 2187, p. 5). These comments suggest that a 5-working-day 
notification period would be too long for many employers in the 
construction industry. Thus, OSHA concludes that it would make little 
sense to lengthen the notification period in the construction standard 
to correspond to the time period proposed in general industry and 
maritime.
    OSHA also concludes that shortening the proposed provision in 
general industry to mirror that in construction would likewise make 
little sense, especially insofar as most of OSHA's health standards for 
general industry already utilize a 15-working-day period. As OSHA 
explained in Phase II of SIPS, ``a uniform time limit for notifying 
employees in general industry has substantial benefits[,]'' including 
reduced employer paperwork burdens because of simpler, uniform 
compliance programs and probable improvement in employee protection due 
to improved compliance. Therefore, OSHA finds that the reasons 
discussed in the SIPS rulemaking apply equally here. Consequently, OSHA 
has chosen to adopt the proposed 5 and 15-working-day assessment 
results notification periods in the rule.
    OSHA has also considered commenters' concerns that the nature of 
construction work will make it

[[Page 16769]]

logistically difficult to notify employees of assessment results 
because they may have moved on to different jobsites or employers. 
Employers have options available for notifying employees in such 
circumstances; for example, notifications could be made individually in 
writing by including the assessment results in the employees' final 
paycheck.
    OSHA considers notification of assessment results to be important, 
even if the work conditions and circumstances have changed by the time 
the assessment results are available. Notification is not simply for 
purposes of identifying appropriate controls at the time the work is 
performed. The assessment results are still relevant after the exposure 
has occurred, to inform employees of their exposure, to provide context 
for future work that may be performed under similar conditions and 
circumstances, and to inform PLHCPs who provide medical surveillance 
for the employee.
    NAM urged OSHA to provide flexibility as to when an assessment is 
deemed complete rather than obligating the employer to notify employees 
within five days of receiving a laboratory result (Document ID 2380, 
Attachment 2, p. 32). NAM argued that employers need time to perform 
and get the results of comprehensive surveys, perform appropriate 
quality assurance of those results, and meet with employees as 
appropriate to discuss the results. OSHA recognizes the value of these 
measures, but also considers the necessity of assessing exposures and 
notifying employees in a timely manner so that appropriate protective 
measures are taken. The Agency is convinced that the required 
notification can be made within the required 15 or 5 day time period, 
which are standard in OSHA health standards. Additional information 
that is developed from the collection of data in comprehensive surveys, 
any revisions to initial results as a result of quality assurance 
activities, or meetings to discuss the assessment results can take 
place at a later date.
    Where the employer follows the performance option provided in 
paragraph (d)(2) of the standard for general industry and maritime 
(paragraph (d)(2)(ii) of the standard for construction), the 15 (or 5) 
day period commences when the employer completes an assessment of 
employee exposure levels (i.e., normally prior to the time the work 
operation commences, and whenever exposures are re-evaluated). OSHA 
expects that many construction employers will follow the performance 
option, where they are not using the specified exposure control methods 
approach. Therefore, OSHA expects that it will not be difficult to 
reach affected employees as the assessment would take place prior to 
the time the work operation begins and the assessment results could 
then be posted in a location accessible to employees at the beginning 
of the job. Where the employer follows the scheduled monitoring option 
provided in paragraph (d)(3) of the standard for general industry and 
maritime (paragraph (d)(2)(iii) of the standard for construction), the 
15 (or 5) day period for notification commences when monitoring results 
are received by the employer.
    In addition, as discussed in the summary and explanation of Scope, 
where tasks performed in a general industry setting may be essentially 
indistinguishable from construction tasks listed on Table 1, OSHA 
permits employers to comply with either all of the provisions of the 
standard for general industry and maritime or all of the provisions of 
the standard for construction. When choosing to follow the construction 
standard, the employer must notify employees within five working days 
after completing an exposure assessment.
    The notification provisions in the rule, like those in the 
proposal, require employers to notify ``affected'' employees. As noted 
above, the term ``affected'' as used here means all employees for which 
an exposure assessment has been conducted, either individually or as 
part of a representative monitoring strategy. It includes employees 
whose exposure was assessed based on other employees who were sampled, 
and employees whose exposures have been assessed on the basis of 
objective data. Several commenters, including Ameren and EEI, suggested 
that notification should only be required where air monitoring has been 
performed, should not be applicable to employers who choose the 
performance option for meeting the exposure assessment requirement, and 
should already be captured by training or a written safety program 
(e.g., Document ID 2315, p. 3; 2357, p. 23). Newmont Mining Corporation 
commented that notification for every exposure assessment would be 
excessive and should only be required when the results change (e.g., 
exposures above the PEL drop below PEL) (Document ID 1963, p. 4).
    OSHA disagrees. Notifying employees of their exposures provides 
them with knowledge that can permit and encourage them to be more 
proactive in working to control their own exposures through better and 
safer work practices and more active participation in safety programs. 
As OSHA noted with respect to its Hazard Communication Standard: 
``Employees provided with information and training on chemical hazards 
are able to fully participate in the protective measures instituted in 
their workplaces'' (77 FR 17574, 17579 (3/26/12)). Exposures to 
respirable crystalline silica below the PEL may still be hazardous, and 
making employees aware of such exposures may encourage them to take 
whatever steps they can, as individuals, to reduce their exposures as 
much as possible. The results of exposure assessment are not 
specifically required to be communicated to employees under the hazard 
communication and employee information and training requirements in 
paragraph (j) of the standard for general industry and maritime 
(paragraph (i) of the standard for construction) nor as a part of the 
written exposure control plan required in paragraph (f)(2) of the 
standard for general industry and maritime (paragraph (g) of the 
standard for construction). Exposure assessments are likely to be 
conducted more frequently than training and, given the differences in 
timing, OSHA concludes that it would not make sense to incorporate them 
into a written exposure control plan. Thus, it is important to separate 
the notification of exposure assessment results from other information 
and training employees are required to receive under the rule.
    NAM offered its opinion on what information the notification should 
provide to employees and urged OSHA to provide flexibility in this 
area:

    Many employers require that air sampling results be accompanied 
by statements concerning the relationship of the results to existing 
standards, practices and procedures required as a result of the 
exposure levels, and a discussion of any steps the employer is 
taking in addition to further control exposures. OSHA acknowledges 
that employees benefit from having information about the exposures 
and potential control measures, including the use of PPE, to reduce 
their risk. OSHA should recognize that an assessment may include 
more than simple analytical results from a laboratory. Therefore, 
OSHA should propose language to make clear that the employers have 
this flexibility in communicating the results to employees (Document 
ID 2380, Attachment 2, p. 32).

    The notification requirement specifies what information must be 
included; however, this does not limit employers from including the 
types of information described by NAM in the written notification to 
employees.

[[Page 16770]]

    The standard also requires employers to either notify each affected 
employee in writing or post the assessment results in an appropriate 
location accessible to all affected employees. CPR urged OSHA to 
strengthen the notification requirements by requiring: Personal 
notification to workers in writing; notification in a language the 
employee can understand; and inclusion of information about the silica 
standard, silica-related disease from an individual or community 
perspective, and available health care benefits (Document ID 2351, p. 
12). The Agency has determined that the notification requirements and 
the training requirements in the rule adequately address these 
suggestions. As discussed, the rule requires employers to notify 
employees, either in writing or by posting in an appropriate location. 
The training requirements in paragraph (j)(3) of the standard for 
general industry and maritime (paragraph (i)(2) of the standard for 
construction) require the employer to ensure that each covered employee 
can demonstrate knowledge and understanding of the silica standard, 
tasks that could result in exposure to respirable crystalline silica, 
the health hazards associated with exposure, specific procedures the 
employer has implemented to protect employees from exposure, and the 
medical surveillance provided under the rule. OSHA intends that these 
requirements will ensure that employees comprehend their exposure to 
respirable crystalline silica, the potential adverse effects of that 
exposure, and protective measures that are available. This would 
include employee understanding of any corrective action the employer is 
taking to reduce exposures below the PEL that is described in the 
written notification. The notification requirement, however, does not 
require that employers provide notification in a language that the 
employee can understand; as with other information provided to 
employees (e.g., labels and safety data sheets), training ensures that 
the information is understood.
    In addition, paragraph (d)(6)(ii) of the standard for general 
industry and maritime (paragraph (d)(2)(vi)(B) of the standard for 
construction) requires that whenever the PEL has been exceeded, the 
written notification must contain a description of the corrective 
action(s) being taken by the employer to reduce employee exposures to 
or below the PEL. Several commenters raised issues with the requirement 
to notify employees about corrective actions being taken where 
exposures are above the PEL. ASA and CISC suggested that in the 
construction environment, five days is not sufficient time to determine 
what caused the exposure, to research alternative solutions to limit 
future exposure, and to decide on the appropriate corrective action 
(Document ID 2187, p. 5; 2319, p. 87; 3442, pp. 3-4).
    Similarly, in the general industry context, Newmont Mining 
Corporation argued that ``[d]etermination of controls to reduce 
exposures when exposure assessments exceed the PEL may take more than 
15 days'' and suggested that OSHA revise the proposed language to allow 
employers 60 to 90 days to develop a corrective action plan and explain 
it to employees (Document ID 1963, p. 4). NAM also noted that the 
requirement to notify employees of the corrective actions being taken 
to reduce employee exposures below the PEL does not make sense for 
situations where it is infeasible to bring the exposure level down to 
the PEL (Document ID 2380, Attachment 2, p. 32).
    OSHA disagrees. In OSHA's view, the requirement to inform employees 
of the corrective actions the employer is taking to reduce the exposure 
level to or below the PEL is necessary to assure employees that the 
employer is making efforts to furnish them with a safe and healthful 
work environment, and is required under section 8(c)(3) of the OSH Act 
(29 U.S.C. 657(c)(3)). OSHA understands that it may take more than 15 
days to determine what engineering controls may be appropriate in a 
particular situation. However, the corrective action described in the 
written notification is not limited to engineering controls; when the 
exposure assessment indicates that exposures exceed the PEL, and the 
employer needs more than 15 days (or, in the case of the standard for 
construction, 5 days) to identify the engineering controls that will be 
necessary to limit exposures to the PEL, the employer is required to 
provide exposed employees with appropriate respiratory protection. In 
such a situation, respiratory protection is the corrective action that 
would be described in the written notification. Similarly, respiratory 
protection is the corrective action that would be described in the 
written notification in situations where it is infeasible to limit 
exposures to the PEL.
    CEG and Upstate Medical University suggested that exposure 
assessment results should not only be reported to employees, but also 
should be reported to OSHA (Document ID 3586, Tr. 3321; 2244, p. 4). 
OSHA has not included such a requirement in the rule as such 
information would not be of practical use to the Agency. OSHA does not 
possess the resources to review and consider all of the material that 
will be generated by employers assessing employee exposures under the 
rule. OSHA would not have sufficient context to consider that material 
even if sufficient resources were available, given that only limited 
information is included in such assessments. Where such information 
would be of practical value to OSHA, such as when compliance staff 
conduct workplace inspections, the Agency is able to review exposure 
records in accordance with the standard addressing access to exposure 
and medical records (29 CFR 1910.1020).
    Observation of monitoring. Paragraph (d)(7) of the standard for 
general industry and maritime (paragraph (d)(2)(vii) of the standard 
for construction) requires the employer to provide affected employees 
or their designated representatives an opportunity to observe any air 
monitoring of employee exposure to respirable crystalline silica, 
whether the employer uses the performance option or the scheduled 
monitoring option. When observation of monitoring requires entry into 
an area where the use of protective clothing or equipment is required 
for any workplace hazard, the employer must provide the observer with 
that protective clothing or equipment at no cost, and assure that the 
observer uses such clothing or equipment.
    The requirement for employers to provide employees or their 
representatives the opportunity to observe monitoring is consistent 
with the OSH Act. Section 8(c)(3) of the OSH Act mandates that 
regulations developed under section 6 of the Act provide employees or 
their representatives with the opportunity to observe monitoring or 
measurements (29 U.S.C. 657(c)(3)). Also, section 6(b)(7) of the OSH 
Act states that, where appropriate, OSHA standards are to prescribe 
suitable protective equipment to be used in dealing with hazards (29 
U.S.C. 655(b)(7)). The provision for observation of monitoring and 
protection of the observers is also consistent with OSHA's other 
substance-specific health standards such as those for cadmium (29 CFR 
1910.1027) and methylene chloride (29 CFR 1910.1052).
    In his testimony, Shawn Ragle of UAW Local 974, in responding to 
Rebecca Reindel of AFL-CIO, described the importance of allowing the 
observation of monitoring:


[[Page 16771]]


    MS. REINDEL: . . . Mr. Ragle, you mentioned that there's limited 
air monitoring in your plant. I was wondering, as a safety rep, have 
you ever been allowed to observe the air monitoring that has been 
done?
    MR. RAGLE: . . . Actually, I've requested to be an observer for 
air monitoring, and the company has denied me that access. They've 
chosen to go with the employee that they put the monitor on.
    Really, if you're doing your job, how are you going to monitor 
your monitor to make sure everything is going correctly? I really 
think that we need to have a little more voice, or at least some 
validation that the monitoring is being done correctly.
    We shouldn't put that on the employee wearing the monitor 
(Document ID 3582, Tr. 1895-1896).

    Similarly, James Schultz, a former foundry employee from the 
Wisconsin Coalition for Occupational Safety and Health, testified that 
he was,

    . . . heartened to see that the proposal mandates that the 
employer provide protective clothing and equipment at no cost to the 
observers that are doing the observation and the monitoring of the 
hazards in the workplace (Document ID 3586, Tr. 3200).

Opposing this requirement, CISC and Hunt Construction Group argued that 
the provision was unnecessary given that the observer will not be close 
enough to the silica-generated tasks to pose a risk (Document ID 2319, 
pp. 87-88; 3442, pp. 4-5). ASA expressed concern about the unnecessary 
cost of providing protective clothing to an observer (Document ID 2187, 
p. 5). Similarly, AGCM argued that requiring the employer to provide 
personal protective equipment and training is an unnecessary additional 
cost and requirement (Document ID 2265, Attachment 1, p. 2).
    Commenters, including the Korte Company and ASA, were also 
concerned that this requirement burdened the employer with providing 
the employee's representative with protective clothing or equipment 
whether or not the representative is trained or qualified to be wearing 
the required PPE (e.g., medical evaluation or fit test to wear a 
respirator) (e.g., Document ID 3230, p. 1; 2187, p. 5). Commenters, 
including NTCA and TCNA, asked OSHA to state that it is the 
responsibility of the employer of the employee's representative to 
provide the necessary respirator and ensure that the employee's 
representative is medically cleared, appropriately trained, and fit 
tested if a respirator is needed to observe the monitoring (e.g., 
Document ID 2267, p. 5; 2363, p. 5). NAHB argued that this provision is 
``neither reasonable nor prudent'' as it ``needlessly impos[es] 
liability on covered employers by requiring them to assume 
responsibility for an `observer' who may come onto a jobsite where 
silica may be present'' (Document ID 2296, p. 25). AGCM argued that the 
observer's employer is already required to provide the necessary 
personal protective equipment and training, not the employer being 
observed (Document ID 2265, Attachment 1, p. 2).
    Section 8(c)(3) of the OSH Act states that occupational safety and 
health standards which require employers to monitor or measure employee 
exposure to potentially toxic materials ``shall provide employees or 
their representatives with an opportunity to observe such monitoring or 
measuring.'' Provisions requiring employers to provide affected 
employees or their designated representatives an opportunity to observe 
any monitoring, as well as protective clothing or equipment where it is 
required, appear in 15 substance-specific health standards. Two 
substance-specific health standards (1,3-butadiene and methylene 
chloride) require employers to ``provide the observer with protective 
clothing or equipment at no cost'' (Sec.  1910.1051(d)(8)(ii) and Sec.  
1910.1052(d)(6)(ii)), as does this rule for respirable crystalline 
silica.
    OSHA's policy conclusion is that employers conducting monitoring 
must bear the cost of complying with the standard's provisions for 
observer protections, even if the observer is not an employee of the 
employer. First, the Agency concludes that it would be an extremely 
rare occurrence for an observer to be unfamiliar with the use of the 
types of protective clothing or equipment that would be necessary for 
observation. In OSHA's experience, observers, whether they are another 
employee or a designated representative, typically have knowledge and 
experience such that they would already be medically cleared to use 
appropriate respiratory protection and may even have access to an 
appropriate respirator. Thus, OSHA expects the employer conducting the 
monitoring in these situations to communicate with the observer about 
what hazards are present in the workplace and what protective clothing 
and equipment, including medical clearances, are needed to observe the 
monitoring at their establishment. OSHA also expects the employer to 
assess whether the observer already has the necessary equipment and 
training to observe the monitoring. In situations where the necessary 
equipment is not already available to the observer, OSHA considers it 
to be the employer's responsibility to provide the protective clothing 
and equipment, as well as other training, clearance, or evaluation 
needed to ensure that the observer uses such clothing and equipment.
    Second, OSHA recognizes that, in some situations, observers may not 
need to enter an area requiring the use of protective clothing or 
equipment in order to effectively observe monitoring. In those cases, 
no protective clothing or equipment is needed by the observer and OSHA 
would not expect or require the employer to provide such observer with 
any protective clothing or equipment. Some possible options to avoid 
exposing the observer to hazards that require the use of protective 
clothing or equipment include conducting the set-up for the monitoring 
outside of hazardous areas and ensuring that the observer can view the 
monitoring while remaining outside of the hazardous areas or, where 
exposure to respirable crystalline silica is the only hazard requiring 
the use of protective clothing or equipment, conducting the set-up for 
monitoring before the exposure-generating task is performed and 
ensuring that the observer can view the monitoring while remaining 
outside of the area of exposure.
    Third, OSHA finds that employers conducting monitoring are in the 
best position to understand the hazards present at the workplace, 
including the protective clothing and equipment needed to protect 
against those hazards and the training, clearance, or evaluation needed 
to ensure that the observer is protected from those hazards. OSHA 
concludes that employers' familiarity with the worksite, the work, and 
their employees puts them in the best position to conduct exposure 
monitoring in a timely, effective, and safe manner. Therefore, OSHA 
appropriately requires the employer to bear the responsibility for 
ensuring that any observer in his or her establishment is adequately 
protected.
    OSHA thus decided that employers conducting monitoring are 
responsible for the full costs of protecting observers, by providing 
the necessary equipment as well as any training, clearance, or 
evaluation needed to properly use the equipment, regardless of whether 
the observers are employees or designated representatives.
    The requirements for exposure assessment in the rule are consistent 
with ASTM E 1132-06, Standard Practice for Health Requirements Relating 
to Occupational Exposure to Respirable Crystalline Silica, and ASTM E 
2625-09, Standard Practice for Controlling Occupational Exposure to 
Respirable Crystalline Silica for

[[Page 16772]]

Construction and Demolition Activities, the national consensus 
standards for controlling occupational exposure to respirable 
crystalline silica in general industry and in construction, 
respectively. Each of these voluntary standards has explicit 
requirements for exposure assessment. For general industry, the ASTM 
standard includes requirements for: Initial sampling; periodic 
sampling; sampling and analytical methods; observation of monitoring; 
and notification of assessment results. Similarly, for construction, 
the ASTM standard includes requirements for: Initial sampling; 
reassessment of exposures when changes have the potential to result in 
new or additional exposures; sampling and analytical methods; and 
notification of assessment results. It also notes the challenges of 
monitoring in a dynamic construction environment and suggests that 
employers may also use a combination of historical data, objective 
data, or site-specific employee exposure monitoring to assess 
exposures.
    While OSHA's standard for respirable crystalline silica includes 
these elements, it includes a performance-oriented approach to exposure 
assessment that best reflects the realities of assessing exposures to 
respirable crystalline silica. The standard also includes a scheduled 
approach, which provides specific requirements for initial and periodic 
monitoring, for industries and tasks that can utilize such an option. 
Including both of these options maximizes the flexibility for employers 
to meet their exposure assessment obligations, and in doing so, better 
effectuates the purposes of the OSH Act and protects employees from 
exposures to respirable crystalline silica. OSHA thus concludes that 
the exposure assessment provision in the rule achieves the important 
purpose of assessing employee exposure, while providing sufficient 
flexibility for employers.

Regulated Areas

    Paragraph (e) of the standard for general industry and maritime 
sets forth the requirements for regulated areas. In paragraph (e)(1), 
employers are required to establish regulated areas wherever an 
employee's exposure to airborne concentrations of respirable 
crystalline silica is, or can reasonably be expected to be, in excess 
of the permissible exposure limit (PEL). In paragraph (e)(2) and 
(e)(3), employers must demarcate regulated areas, and limit access to 
regulated areas to persons authorized by the employer and required by 
work duties to be present in the regulated area, persons observing 
exposure monitoring, or any person authorized by the Occupational 
Safety and Health (OSH) Act or regulations issued under it to be in a 
regulated area. Finally, paragraph (e)(4) requires employers to provide 
each employee and the employee's designated representative entering a 
regulated area with an appropriate respirator and require its use while 
in the regulated area.
    The requirements for regulated areas serve several important 
purposes. First, requiring employers to establish and demarcate 
regulated areas ensures that the employer makes employees aware of the 
presence of respirable crystalline silica at levels above the PEL. 
Second, the demarcation of regulated areas must include warning signs 
describing the dangers of respirable crystalline silica exposure in 
accordance with paragraph (j) of the standard for general industry and 
maritime, which provides notice to employees entering or nearing 
regulated areas of the posted dangers. Third, limiting access to 
regulated areas restricts the number of people potentially exposed to 
respirable crystalline silica at levels above the PEL and ensures that 
those who must be exposed are properly protected, thereby limiting the 
serious health effects associated with such exposure.
    The proposed requirements for regulated areas were included in 
paragraph (e) of both the proposed standard for general industry and 
maritime and the proposed standard for construction. Under proposed 
paragraph (e)(1), employers would have been required to establish and 
implement either a regulated area or an access control plan wherever an 
employee's exposure to airborne concentrations of respirable 
crystalline silica is, or reasonably could be expected to be, in excess 
of the PEL. The substantive requirements for the regulated area option 
were contained in proposed paragraph (e)(2) and those for access 
control plans were in proposed paragraph (e)(3). In the standard for 
general industry and maritime, OSHA has retained the requirement for 
employers to establish and implement regulated areas. However, the 
Agency has decided against requiring regulated areas in the standard 
for construction; an alternate provision has been included as a 
component of the written exposure control plan requirements for 
construction.
    OSHA has concluded that requirements for regulated areas are 
appropriate for general industry and maritime, but not for 
construction, because the worksites and conditions and other factors, 
such as environmental variability normally present in the construction 
industry, differ substantially from those typically found in general 
industry. Commenters, including the National Council of La Raza, the 
National Institute for Occupational Safety and Health (NIOSH), the 
Associated General Contractors of America, the Small Business 
Administration's Office of Advocacy, and the Building and Construction 
Trades Department, AFL-CIO (BCTD), noted some of the differences 
between construction and general industry worksites, including that 
general industry establishments are typically more stable, are likely 
to be indoors, and are usually at a fixed location (e.g., Document ID 
2166, p. 3; 2177, Attachment B, p. 7; 2323, p. 1; 2349, pp. 5-6; 2371, 
Attachment 1, p. 42). OSHA finds that these factors make establishing 
regulated areas generally suitable in general industry and maritime 
workplace settings, and their absence in construction settings makes a 
regulated areas requirement generally unworkable.
    Some commenters, particularly those representing unions in general 
industry, supported the idea of regulated areas wherever an employee's 
exposure to airborne concentrations of respirable crystalline silica 
is, or reasonably could be expected to be, in excess of the PEL (e.g., 
Document ID 2282, Attachment 3, p. 2; 2315, p. 3; 2318, p. 10). For 
example, the International Brotherhood of Teamsters stated that 
ancillary provisions, such as regulated areas, would reduce the risk 
beyond the reduction that will be achieved by a new PEL alone (Document 
ID 2318, p. 10). Similarly, the United Automobile, Aerospace and 
Agricultural Implement Workers of America (UAW) expressed concerns that 
workers would not receive adequate protection if OSHA did not adopt a 
requirement for regulated areas in general industry (Document ID 2282, 
Attachment 3, pp. 2, 16). The United Steelworkers said that OSHA's 
proposed general industry and maritime standard should be revised to 
require employers to establish regulated areas where processes exceed 
the proposed PEL for respirable crystalline silica (Document ID 2336, 
p. 5).
    Other general industry stakeholders argued that establishing 
regulated areas would be unworkable and infeasible, particularly in 
foundries (Document ID 1992, p. 10; 2149, p. 2; 2248, p. 7; 2349, p. 5; 
2379, Attachment B, pp. 30-31; 3584, Tr. 2669) and in certain other 
sectors of general industry (Document ID 1785, p. 6; 2337, p. 1; 2348, 
p. 36; 2380, Attachment 2, pp. 32-33). Some of these commenters focused 
on how an employer would be able to determine

[[Page 16773]]

which parts of the facility should be designated as regulated areas. 
For example, the American Foundry Society (AFS) indicated that defining 
a regulated area would be difficult because the standard is based on 
employee 8-hour time weighted average (TWA) exposures, not on specific 
geographic areas (Document ID 2379, Attachment B, pp. 30-31). AFS 
explained that ``[i]f the standard allowed real time monitoring and 
exposure mapping as an alternative to 8 hr. TWA sampling, one might be 
able to construct a basis for defining regulated areas'' (Document ID 
2379, Attachment B, pp. 30-31). AFS offered a specific example to 
illustrate its concern:

. . . a maintenance worker who has an exposure above the PEL may 
work in many areas of the plant including the office. It does not 
make sense to turn the office into a regulated area because the 
maintenance worker spent some time there on the day of sampling 
(Document ID 2379, Attachment B, pp. 30-31; 3487, p. 21).

    The scenario described by AFS is not consistent with the definition 
of the term ``regulated area'' that OSHA proposed nor that of the final 
standard. Paragraph (b) of the proposed and final standard for general 
industry and maritime defines regulated area to mean ``an area, 
demarcated by the employer where an employee's exposure to airborne 
concentrations of respirable crystalline silica exceeds, or can 
reasonably be expected to exceed, the PEL.'' This definition makes 
clear that a regulated area is defined by employee exposure, not by 
which employee(s) might be in it. In other words, just because a 
particular employee's exposure assessment results indicate that the 
employee's exposure is above the PEL, that does not mean that employee 
exposure in every area that the employee visited on the day he or she 
was sampled exceeds, or can reasonably be expected to exceed, the PEL.
    In the scenario posed by AFS, the employer would be required by 
paragraph (d)(1) of the standard for general industry and maritime to 
assess the exposure of each employee who is, or may reasonably be 
expected to be, exposed to respirable crystalline silica at or above 
the action level in accordance with either the performance option 
(i.e., use of any combination of air monitoring data or objective data 
sufficient to accurately characterize employee exposure) or the 
scheduled monitoring option (i.e., one or more personal breathing zone 
air samples). As explained in the summary and explanation of Exposure 
Assessment, if real time monitoring and exposure mapping, the methods 
suggested by AFS, allow an employer to accurately characterize employee 
exposures, then the employer would be allowed to use such methods to 
assess employee exposures under the performance option. This exposure 
information would also be helpful in determining where higher exposures 
may be occurring.
    If an employee's exposure is above the PEL, paragraph (f)(1) of the 
standard for general industry and maritime would require the employer 
to use engineering and work practices to reduce and maintain employee 
exposure to respirable crystalline silica. In order to control 
exposures, the employer would need to determine where the exposures are 
generated. As explained by Dr. Franklin Mirer, Professor of 
Environmental and Occupational Health at CUNY School of Public Health, 
during his testimony on behalf of the American Federation of Labor and 
Congress of Industrial Organizations (AFL-CIO), setting up a regulated 
area in a foundry is not complicated--employers must simply determine 
the extent of the dust cloud, possibly using measures like short-term 
or real-time monitoring or exposure mapping (Document ID 3578, Tr. 
1003-1005).
    Dr. William Bunn, who testified on behalf of the U.S. Chamber of 
Commerce, also offered testimony that suggests that some foundries are 
capable of establishing regulated areas. In response to questioning 
during the public hearings, Dr. Bunn spoke about the efficacy of OSHA 
inspections for aiding foundries in reducing silica exposures. Based on 
his experience as an employee of Navistar International and as a 
consultant to multiple automotive engine foundries, Dr. Bunn stated 
that there was no feasible way to attain compliance with the proposed 
PEL without using respiratory protection. However, Dr. Bunn emphasized 
that this occurred at certain specific, restricted areas that could be 
easily observed (Document ID 3576, Tr. 473). OSHA concludes from this 
testimony that where exposures above the PEL occur in foundries, they 
typically occur in limited areas that can be readily identified, and 
the provisions for establishment, demarcation, access restriction, and 
provision of respirators can be applied.
    Edison Electric Institute stated that, given requirements for 
establishing regulated areas in other OSHA substance-specific 
standards, OSHA should consider creating uniform provisions for 
regulated areas, to minimize the complications that arise when multiple 
regulated substances begin to ``stack'' in one regulated area (Document 
ID 2357, pp. 32-33). OSHA recognizes that standards for asbestos, 
benzene, cadmium, chromium (VI), 13 carcinogens, methylenedianiline, 
and others also contain requirements for regulated areas; however, 
these requirements are not in conflict with one another. Where an 
employer establishes a regulated area for multiple substances, the 
employer can and must comply with the requirements for each applicable 
standard for that regulated area. Persons allowed access to the 
regulated area include employees who are performing tasks required by 
work duties subject to the regulated area requirements of another 
standard even if that exposure (e.g., to asbestos) is unrelated to 
tasks that generate silica exposures. But this would be a very uncommon 
scenario--for the most part, multiple standards apply when exposures to 
multiple hazardous substances result from a single source, e.g., fly 
ash in electric utilities contains lead, chromium (VI), silica, etc.
    Other general industry commenters felt that regulated areas were 
unnecessary. For example, Morgan Advanced Materials asserted that 
regulated areas or access control programs may be appropriate for areas 
where the conditions may cause an immediate health effect or injury, 
but are not appropriate for chronic hazards like respirable crystalline 
silica, especially since ``. . . nearly everyone is exposed to some 
level of crystalline silica on a daily basis'' (Document ID 2337, pp. 
1-2). OSHA rejects Morgan Advanced Materials' position because, unlike 
``everyone'' who is exposed to background levels, employees who are 
exposed to respirable crystalline silica at levels exceeding the 
revised PEL are at significant risk of developing silica-related 
disease; this risk cannot be ignored simply because silica exposure 
does not cause an immediate death or injury. Regulated areas are an 
effective means of limiting the risk associated with respirable 
crystalline silica exposure, and are therefore appropriate for 
protecting employees.
    Paragraph (e)(2) of the standard for general industry and maritime 
includes requirements for demarcation of regulated areas. The proposed 
provision on demarcation would have required employers to demarcate 
regulated areas from the rest of the workplace in any manner that 
adequately establishes and alerts employees to the boundary of the 
regulated area. The proposed provision also stipulated that the 
demarcation minimize the number of employees exposed to respirable 
crystalline silica within regulated areas. In the proposed

[[Page 16774]]

rule, OSHA did not specify how employers were to demarcate regulated 
areas. In the standard for general industry and maritime, because the 
Agency has adopted requirements for posting signs, OSHA has removed the 
language ``in any manner that adequately establishes and alerts 
employees to the boundary of the regulated area.''
    A number of stakeholders submitted comments on the proposed 
provision. For example, the AFL-CIO argued that other health standards 
that regulate carcinogens require warning signs at regulated areas, and 
that OSHA provided no justification for departing from this precedent 
(Document ID 4204, pp. 56-57). Many other stakeholders were supportive 
of warning sign requirements and submitted specific language for 
inclusion on signs that demarcate regulated areas (Document ID 2163, 
Attachment 1, p. 15; 2178, pp. 2-3; 2282, Attachment 3, p. 25; 2310, 
Attachment 2, p. 1; 2371, Attachment 1, p. 36; 2373, p. 2; 3582, Tr. 
1920-1921; 4030, Attachment 1, p. 3; 4030, Exhibit D; 4073, Exhibit 
15b, p. 18). For example, BCTD and the International Union of Operating 
Engineers encouraged OSHA to review the discussion of regulated areas 
in Ontario's Guideline on Silica Construction Projects with respect to 
ropes and barriers (Document ID 4073, Attachment 15b; 4234, Attachment 
2, p. 57). Ontario's Guideline states that:

    Ropes or barriers do not prevent the release of contaminated 
dust or other contaminants into the environment. However, they can 
be used to restrict access of workers who are not adequately 
protected with proper PPE, and also prevent the entry of workers not 
directly involved in the operation. Ropes or barriers should be 
placed at a distance far enough from the operation that allows the 
silica-containing dust to settle. If this is not achievable, warning 
signs should be posted at the distance where the silica-containing 
dust settles to warn that access is restricted to persons wearing 
PPE (Document ID 4073, Ex.15 b).

    Others identified particular topics that should be covered by the 
signs without proposing language. For example, Upstate Medical 
University argued that all regulated areas should have warning signs 
addressing the hazards of silica dust (Document ID 2244, p. 4).
    As is further explained in the summary and explanation of 
Communication of Respirable Crystalline Silica Hazards to Employees, 
OSHA agrees with these commenters with respect to the requirement for 
warning signs at entrances to regulated areas. Employees must recognize 
when they are entering a regulated area, and understand the hazards 
associated with the area, as well as the need for respiratory 
protection. Signs are an effective means of accomplishing these 
objectives. Therefore, OSHA has included a requirement that employers 
are obligated to post all entrances to regulated areas with signs that 
bear the following legend:

DANGER
RESPIRABLE CRYSTALLINE SILICA
MAY CAUSE CANCER
CAUSES DAMAGE TO LUNGS
WEAR RESPIRATORY PROTECTION IN THIS AREA
AUTHORIZED PERSONNEL ONLY

    The rulemaking record also indicates that use of signs is also 
consistent with general industry practices. For example, a plan 
developed by the National Service, Transmission, Exploration, and 
Production Safety Network (STEPS Network) for the hydraulic fracturing 
industry recommends signs to warn of potential silica exposure and the 
requirement for respirator use near exposure zones (Document ID 4024, 
Attachment 1, p. 1; Attachment 2, p. 1).
    The Unified Abrasives Manufacturers Association argued that 
demarcation of regulated areas would require the construction of a 
complete physical separation between the regulated area and adjacent 
areas (Document ID 3398, p. 1). Aside from the requirement of specific 
language for posting signs, however, the standard does not specify the 
method of demarcation; cones, stanchions, tape, barricades, lines, or 
textured flooring may each be effective means of demarcating the 
boundaries of regulated areas. As in the proposed rule, therefore, so 
long as the demarcation is accomplished in a manner that minimizes the 
number of employees exposed to respirable crystalline silica within the 
regulated area, the employer will be in compliance, without necessarily 
installing a complete physical separation in the workplace.
    Factors that OSHA considers to be appropriate considerations for 
employers when they are determining how to demarcate regulated areas 
include the configuration of the area, whether the regulated area is 
permanent, the airborne respirable crystalline silica concentration, 
the number of employees in adjacent areas, and the period of time the 
area is expected to have exposure levels above the PEL. Permitting 
employers to choose how best to demarcate regulated areas is consistent 
with OSHA's use of performance-based approaches where the Agency has 
determined that employers, based on their knowledge of the specific 
conditions of their workplaces, are in the best position to make such 
determinations.
    The flexibility of this provision aims to address some of the 
concerns identified by commenters. For example, National Electrical 
Carbon Products commented that:

    The concept seems to be that there are hazardous areas where 
access must be restricted. In reality: there are hazardous 
exposures, where exposures must be controlled . . . Exposure to 
airborne crystalline silica, on the other hand, is most typically 
associated with intermittent activities that are not necessarily 
associated with a location (Document ID 1785, p. 6).

OSHA understands that for certain work processes, exposure may indeed 
be associated with an intermittent activity rather than a fixed 
location. In such cases where silica-generating activities are 
conducted only sporadically, employers may elect to demarcate a 
regulated area by means of movable stanchions, portable cones, 
barricade tape, and the like, as long as the required warning sign with 
prescribed hazard language is posted at all entrances to each regulated 
area. Similarly, in a case where work activity migrates to different 
areas of a worksite, these movable forms of demarcation could likewise 
be repositioned to indicate the regulated area as work progresses. This 
flexibility should also help employers with open-design facilities 
establish regulated areas when needed.
    A few commenters expressed concern that provisions for demarcation 
of regulated areas may interfere with heat stress programs currently in 
place as well as the current sanitation standard in general industry 
(29 CFR 1910.141) (Document ID 2379, Appendix 1, p. 59; 3577, Tr. 751-
752; 3586, Tr. 3370). The AFS stated that:

    Foundries often have areas with high heat exposures and 
encourage workers to drink water. The proposal [is] not clear on 
hygiene rules for regulated areas. The final rule must not be 
drafted in a way that could be interpreted to ban drinking water in 
a regulated area (Document ID 2379, Appendix 1, p. 59).

    OSHA's standards addressing sanitation in general industry and 
maritime with respect to consumption of food and beverages are 
unchanged by this rulemaking. The standards in paragraphs 29 CFR 
1910.141(g)(2) and 1917.127(c) prohibit consumption of food or beverage 
in any area exposed to a toxic material. OSHA appreciates the 
importance of providing access to drinking water, particularly in hot 
work environments, and recognizes that in many cases employees will 
need access to drinking water in order to remain

[[Page 16775]]

hydrated. However, as explained in more detail below, paragraph (e)(4) 
of the standard for general industry and maritime requires all 
employees within the demarcated boundaries of a regulated area to wear 
a respirator continually while in the area, and thereby the consumption 
of water within boundaries of a regulated area is not feasible. An 
employee will need to leave the regulated area temporarily to access 
water and food, in accordance with OSHA's sanitation standards.
    Paragraph (e)(3) of the standard for general industry and maritime 
requires employers to limit access to regulated areas. As in the 
proposed rule, employers are required to limit access to: (A) Persons 
authorized by the employer and required by work duties to be present in 
the regulated area; (B) any person entering such an area as designated 
representatives of employees for the purpose of exercising the right to 
observe exposure monitoring procedures under paragraph (d) of this 
section; and (C) any person authorized by the OSH Act or regulations 
issued under it to be in a regulated area.
    The first group, persons the employer authorizes or requires to be 
in a regulated area to perform work duties, includes employees and 
other persons whose jobs involve operating machinery, equipment, and 
processes located in regulated areas; performing maintenance and repair 
tasks on machinery, equipment, and processes in those areas; conducting 
inspections or quality control tasks; and supervising those who work in 
regulated areas. Persons allowed access to the regulated area include 
employees who are performing tasks required by work duties subject to 
the regulated area requirements of another standard even if that 
exposure is unrelated to tasks that generate silica exposures.
    The second group is made up of persons entering a regulated area as 
designated representatives of employees for the purpose of exercising 
the right to observe exposure monitoring under paragraph (d) of the 
standard for general industry and maritime. As explained in the summary 
and explanation of Exposure Assessment, providing employees and their 
representatives with the opportunity to observe monitoring is 
consistent with the OSH Act and OSHA's other substance-specific health 
standards, such as those for cadmium (29 CFR 1910.1027) and methylene 
chloride (29 CFR 1910.1052).
    The third group consists of persons authorized by law to be in a 
regulated area. This category includes persons authorized to enter 
regulated areas by the OSH Act, OSHA regulations, or any other 
applicable law. OSHA compliance officers fall into this group.
    Some commenters expressed concerns about restricting access to 
regulated areas. For example, OSCO Industries argued that control of 
ingress and egress from regulated areas would be very problematic 
because of high traffic volumes, indicating, for example, that it may 
be necessary to reroute pedestrian and fork truck traffic outside the 
building in order to avoid the regulated area (Document ID 1992, p. 
10). Similarly, a representative of the Non-Ferrous Founders' Society 
(NFFS) testified that smaller foundries would experience difficulty in 
establishing and restricting access to regulated areas (Document ID 
3584, Tr. 2814).
    Other commenters indicated that restricted areas were already in 
place at their workplaces. For example, Kenny Jordan, Executive 
Director of the Association of Energy Service Companies, testified that 
restricted areas with limited access are already used in hydraulic 
fracturing operations (Document ID 3589, Tr. 4066-4067). Mr. Jordan 
went on to describe how the presence of these restricted areas is 
communicated to other employees on the multiemployer worksite (Document 
ID 3589, Tr. 4079-4080).
    OSHA finds that requirements for establishing and limiting access 
to regulated areas are reasonable and generally feasible for general 
industry and maritime workplaces. With regard to the concerns expressed 
by OSCO Industries about rerouting traffic to avoid regulated areas, 
the intent of the standard is to restrict unnecessary pedestrian and 
vehicle traffic in areas where exposures exceed the PEL; employees who 
would otherwise be exposed when traversing the regulated area will thus 
be better protected. Where work duties require these employees to enter 
the regulated area, the standard provides for access, with appropriate 
respiratory protection. OSHA also considers that the exposure 
assessment performed in accordance with paragraph (d) of the standard 
for general industry and maritime will provide a basis for establishing 
the boundaries of the regulated area, and thus establishment of 
regulated areas will not be as problematic as NFFS suggests.
    Paragraph (e)(4) of the standard for general industry and maritime 
requires employers to provide each employee and the employee's 
designated representative entering a regulated area with an appropriate 
respirator in accordance with paragraph (g) of the standard. The 
provision also mandates that employers require each employee or 
employee representative to use the respirator while in the regulated 
area. The provision in the standard requiring use of respirators in 
regulated areas is identical to the proposed provision. The boundary of 
the regulated area indicates where respirators must be donned prior to 
entering, and where respirators can be doffed, or removed, upon exiting 
the regulated area. This provision was intended to establish a clear 
and consistent requirement for respirator use for all employees who 
enter a regulated area, regardless of the duration of their presence in 
the regulated area.
    OSHA received comments from stakeholders in both construction and 
general industry, generally opposing this requirement (e.g., Document 
ID 1785, p. 7; 2267, p. 5; 2291, p. 25; 2296, p. 26; 2319, p. 90; 2348, 
p. 36; 2363, p. 5; 2380, Attachment 2, pp. 32-33; 3577, Tr. 752; 3586, 
Tr. 3408-3417). For example, the National Association of Home Builders 
(NAHB) stated that the proposed requirements were overly restrictive 
because respiratory protection would be required even when risks are 
low, such as when an employee was in a regulated area for a very short 
period of time (Document ID 2296, p. 30). Several commenters 
representing general industry entities also expressed similar concerns 
with respect to increases in respirator usage (e.g., Document ID 1785, 
p. 7; 2291, p. 25; 2337, p. 1; 2348, p. 36; 2380, Attachment 2, pp. 32-
33; 4229, p. 25). The Asphalt Roofing Manufacturers Association (ARMA) 
indicated that the proposed requirement for respirator use would place 
a significant and unnecessary burden on ARMA member companies (Document 
ID 2291, p. 25). The National Association of Manufacturers (NAM) 
recommended that OSHA should limit requirements for respirator use to 
situations where entry into the regulated area will be of such 
frequency and duration as to constitute a hazard (Document ID 2380, 
Attachment 2, pp. 32-33). National Electrical Carbon Products also 
expressed concerns about the requirements for respirators in regulated 
areas, and encouraged the adoption of a time specification. They argued 
that the proposed requirement was inconsistent with the concept of the 
8-hour TWA PEL (Document ID 1785, p. 7).
    After reviewing these comments, OSHA has decided to retain the 
requirement for employers to provide and require the use of respirators 
in regulated areas in the standard for general industry and maritime. 
Although OSHA recognizes that some employees entering regulated areas 
may not be exposed above the PEL (expressed as an 8-hour TWA), many

[[Page 16776]]

employees who are assigned to work in these areas may remain in these 
locations for long enough periods of time so that they would be 
needlessly overexposed to respirable crystalline silica if they did not 
wear respirators. Furthermore, OSHA finds that allowing some employees 
to work in regulated areas without respiratory protection, while 
requiring it for others, would create confusion and compliance 
difficulties in the workplace. To the extent that some employees in 
regulated areas who may not be exposed on a particular day above the 
PEL are nonetheless required to wear respirators, this time-limited use 
of respirators should further reduce the significant risk that remains 
at the PEL.
    In the proposed rule, OSHA also included a provision related to 
protective work clothing. Proposed paragraph (e)(2)(v)(A) would have 
required employers to either provide protective clothing or provide 
other means of removing excessive silica dust from contaminated 
clothing. Under proposed paragraph (e)(2)(v)(B), employers would have 
been required to ensure that clothing was removed or cleaned upon 
exiting a regulated area when there was potential for employees' 
clothing to become ``grossly contaminated'' by fine particles of 
crystalline silica that could become airborne and inhaled. The purpose 
was not to protect employees from dermal exposure to silica, but rather 
to protect the employee from those situations wherein contamination of 
clothing has the potential to contribute significantly to employee 
inhalation of respirable crystalline silica.
    The proposed provision for protective clothing was more limited 
than similar provisions in other OSHA substance-specific standards. As 
noted in the preamble of the Notice of Proposed Rulemaking OSHA limited 
the proposed provision for protective clothing to regulated areas 
because dermal exposure to crystalline silica is not associated with 
adverse health effects. Nonetheless, OSHA solicited information from 
stakeholders regarding protective clothing for respirable crystalline 
silica, largely because a provision for protective clothing had been 
recommended by the Agency's Advisory Committee on Construction Safety 
and Health.
    Several employees in silica-exposed industries described the extent 
of contamination to their clothing by silica dust and how this dust 
would even be brought home with them (Document ID 3571, Attachment 7, 
p. 1; 3581, Tr. 1595, 1599-1600; 3582, Tr. 1840). OSHA heard testimony 
from Dan Smith, Director of Training for the Bay Area Roofers and 
Waterproofers Training Center in Livermore, California and member of 
the National Curriculum Development Committee of the United Union of 
Roofers, Waterproofers and Allied Workers, which represents roughly 
25,000 workers. Mr. Smith said:

    Some years back, one of my members walked into my office with a 
very unusual object: a plumbing trap. [He] handed it to me. First 
thing I noticed, it was pretty heavy, two to three pounds. He said, 
`That's from my shower at home.' At the time, he had been in the 
tile industry, cutting tile for about 10 years. He said, `My drain 
kept getting clogged. No matter what I put in there, I couldn't get 
it unclogged. I called the plumber. He couldn't get it unclogged. He 
took it off. I looked inside. It was filled with . . . what I would 
call reconstituted cement.' This came off of his body (Document ID 
3581, Tr. 1599-1600).

UAW Local 523 President Jeff P'Poole spoke about making silicon metal 
out of granite with an electric arc furnace reduction process, ``. . . 
people come out with like raccoon eyes . . . you'll look like a coal 
miner at times . . .'' (Document ID 3582; Tr. 1840). Construction 
employee Santiago Hernandez testified that employees often have to 
throw away their work clothing because dust remains embedded even after 
washing the clothes (Document ID 3571, Attachment 7, p. 1).
    OSHA received comments supporting a requirement for employer 
provision of work clothing, or storage, handling, removal and cleaning 
responsibilities for contaminated work clothing (Document ID 2212, p. 
2; 2256, Attachment 2, p. 11; 2277, p. 4; 2310, Attachment 1, pp. 2-4; 
2315, p. 9; 3586, Tr. 3199-3200). For example, the International Safety 
Equipment Association requested that OSHA require employers to provide 
protective garments at no cost to the employee, indicating that this 
would be consistent with other OSHA standards that require employers to 
pay for personal protective equipment (Document ID 2212, p. 2).
    However, numerous comments received on the provision for protective 
work clothing in regulated areas were opposed to OSHA's proposed 
requirement for employers to either provide protective clothing or 
other means of removing excessive silica dust from contaminated 
clothing, and to ensure that clothing is removed or cleaned upon 
exiting a regulated area when there is potential for employees' 
clothing to become grossly contaminated by silica dust (Document ID 
1785, p. 8; 2116, Attachment 1, p. 11; 2187, p. 6; 2195, p. 7; 2296, p. 
40; 2319, pp. 90-91; 2337, p. 2; 2339, p. 8; 2357, pp. 29-30; 2363, p. 
6; 3577, Tr. 713-714; 3580, Tr. 1376-1377; 3584, Tr. 2669; 4035, p. 9). 
Many contended that the language in the provision was vague or 
subjective. For example, the Tile Council of North America, the 
National Tile Contractors Association, and Morgan Advanced Materials 
argued that the term ``grossly'' is subjective, and its use in this 
context would subject the employer to the whim of the compliance 
inspector (Document ID 2267, p. 6; 2363, p. 6; 2337, p. 2).
    The American Society of Safety Engineers (ASSE) indicated that no 
special clothing should be required, as crystalline silica does not 
present a hazard from skin contact. Instead, ASSE suggested that 
employers need to implement programs to assure employees whose clothing 
is contaminated with crystalline silica do not create exposure issues 
outside of the workplace (Document ID 2339, p. 8). NAHB argued that 
protective clothing such as coveralls would be difficult for workers in 
residential construction to use because coveralls frequently restrict 
movement, are often not durable enough for the conditions encountered 
in construction, and could contribute to heat stress (Document ID 2296, 
p. 40).
    The evidence regarding the extent to which dust-contaminated 
clothing may exacerbate employee exposure to respirable crystalline 
silica is mixed. NIOSH stated that past studies have shown a 
significant increase in workers' respirable dust exposure from 
contaminated work clothing, referencing a Bureau of Mines study 
involving highly-exposed machine operators bagging mineral products 
into paper bags (Document ID 2177, Attachment B, p. 15). On the other 
hand, the National Industrial Sand Association (NISA) stated that:

    NISA member companies have years of experience conducting root 
cause analyses of exceedances of the PEL. In that experience, 
contaminated work clothing can be the source of such an exceedance, 
but such circumstances are uncommon (Document ID 2195, p. 37).

    OSHA agrees that contaminated work clothing can contribute to 
respirable dust exposures in some circumstances, as NIOSH indicated. 
However, OSHA concludes that the evidence in the rulemaking record does 
not show that contaminated work clothing contributes appreciably to 
employee exposures to respirable crystalline silica in workplace 
conditions covered by this rule. OSHA is therefore not including a 
requirement for protective clothing in the rule because it is unable to 
determine that the use of protective clothing would

[[Page 16777]]

provide appreciable protection from inhalation of respirable 
crystalline silica in most circumstances. OSHA understands that many of 
the activities covered under the rule involve generation of substantial 
amounts of dust. However, the dust of concern in this rulemaking is 
composed only of respirable crystalline silica particles--those 
particles small enough to penetrate deep into the lungs. OSHA proposed 
protective clothing requirements in regulated areas in an attempt to 
focus on those areas in the workplace where high exposures to 
respirable crystalline silica occur. However, it is not clear that 
measures to address dust on employees' clothing are likely to have any 
meaningful effect on exposures to respirable crystalline silica in most 
workplaces covered by the rule.
    Protective clothing is primarily designed to mitigate against 
dermal hazards, which are not the problem here; nor is dermal exposure 
(as opposed to respiratory exposure) the mechanism by which silica 
causes its adverse health effects. Therefore, special or employer-
provided protective clothing would be no more protective than ordinary 
clothing in this context. Moreover, OSHA understands the practical 
difficulty that employers would encounter in attempting to determine 
when clothing is sufficiently contaminated to trigger a requirement for 
protective measures. Therefore, OSHA has not included a requirement for 
employers to provide protective work clothing or other means of 
removing silica dust from clothing in the rule. There may be instances 
where providing protective clothing or other means of removing 
excessive silica dust from clothing are feasible methods of limiting 
employee exposures to respirable crystalline silica; in such cases, 
these methods become an option for complying with the requirement to 
limit employee exposures to the PEL.
    OSHA has also decided not to include the proposed option to 
establish and implement an access control plan in lieu of a regulated 
area in the rule. As noted above, paragraph (e)(1) of the proposed 
standards for general industry/maritime and construction would have 
required the establishment and implementation of either a regulated 
area or an access control plan wherever an employee's exposure to 
airborne concentrations of respirable crystalline silica is, or 
reasonably could be expected to be, in excess of the PEL. OSHA 
recognized that establishing regulated areas in some workplaces might 
be difficult. As such, the Agency proposed an option for establishing 
and implementing a written access control plan in lieu of a regulated 
area.
    The option for a written access control plan contained provisions 
for: A competent person to identify the presence and location of areas 
where respirable crystalline silica exposures exceed the PEL; notifying 
employees and demarcating such areas; communicating with other 
employers on multi-employer worksites; limiting access to areas where 
exposures exceed the PEL; providing respirators; and addressing 
measures regarding contaminated work clothing. The proposed rule also 
included a requirement for an annual employer review and evaluation of 
the written access control plan, and the plan was to be made available 
upon request for examination and copying to employees, their 
representatives, and the Assistant Secretary and the Director.
    The intent of the provision for establishing written access control 
plans in lieu of regulated areas was to provide employers with 
flexibility to adapt to the particular circumstances of their worksites 
while maintaining equivalent protection for employees. The option for 
establishing a written access control plan was thought to be best 
suited for changing or mobile worksites such as those found in 
construction and utilities.
    The North American Insulation Manufacturers Association supported 
the option for a written access control plan, claiming that it is 
similar to current mineral wool industry practices for limiting access 
(Document ID 2348, p. 36). The National Concrete Masonry Association 
and approximately five of its member companies stated that access 
control plans may be effective for tasks in which personal protective 
equipment is needed (e.g., mixer cleaning), but not for operations that 
cannot be performed in a controlled, limited areas (e.g., general plant 
clean-up) (e.g., Document ID 2279, p. 10; 2388, p. 9).
    Commenters including American Subcontractors Association (ASA), 
Leading Builders of America (LBA), NAHB, and the Construction Industry 
Safety Coalition (CISC), thought that a written access control plan was 
impractical in the construction industry, stating reasons such as 
uncertainty about its requirements or how such plans would differ from 
a regulated area (e.g., Document ID 2187, p. 5; 2269, p. 22; 2296, pp. 
25-26; 2319, pp. 88-89). Additionally, the Communication Workers of 
America (CWA), UAW, and AFL-CIO felt that, given issues of 
enforceability, it did not appear the written access control plan would 
adequately protect workers and limit access to high-exposure work 
areas. Thus, CWA, UAW, and AFL-CIO recommended elimination of the 
option for a written access plan, and for the provision to be limited 
to a regulated areas requirement only (Document ID 2240, p. 2; 2282, 
Attachment 3, p. 16; 3578, Tr. 924-925). Fann Contracting, Inc. 
indicated that neither written access control plans nor regulated areas 
were conducive to outdoor, heavy highway and road and bridge 
construction where the entire worksite has potential for silica 
exposure (Document ID 2116, Attachment 1, pp. 26-27).
    OSHA concludes that the option for a written access control plan 
may prove less protective and would be difficult to enforce, so has 
decided not to include the option for employers to develop and maintain 
written access control plans in lieu of regulated areas in the rule. 
OSHA no longer views a written access control plan to be a viable 
substitute for establishment and maintenance of regulated areas in the 
rule, especially in light of its decision not to include a regulated 
areas requirement in the standard for construction. The requirement for 
a competent person in paragraph (g)(4) of the standard for construction 
provides an alternate approach to restricting access to areas where 
high exposures can occur, and OSHA's expectation is that it will 
achieve a comparable level of protection without imposing the burden of 
maintaining a written access control plan.
    The decision not to require regulated areas in the standard for 
construction reflects OSHA's acknowledgment of the impracticality of 
establishing and demarcating regulated areas in many construction 
industry workplaces. However, as described in further detail in the 
summary and explanation of Written Exposure Control Plan, OSHA has 
concluded that implementing a written exposure control plan, which 
includes a requirement to describe procedures to restrict access to 
work areas, is practical in construction industry workplaces. OSHA 
notes that a written access control plan as contemplated in the 
proposed rule is different from a written exposure control plan as 
mandated in the rule. Written exposure control plans are included in 
the industry consensus standards: ASTM E 1132-06, Standard Practice for 
Health Requirements Relating to Occupational Exposure to Respirable 
Crystalline Silica and ASTM E 2625-09, Standard Practice for 
Controlling Occupational Exposure to Respirable Crystalline Silica for 
Construction and Demolition Activities

[[Page 16778]]

(Document ID 1466, p. 2; 1504, p. 2). OSHA finds that written exposure 
control plans provide a systematic approach for ensuring proper 
function of engineering controls and effective work practices that can 
prevent overexposures from occurring. The ASTM standards do not 
specifically call for procedures to restrict access; however, they do 
call for a description of administrative controls to reduce exposures 
(Document ID 1466, p. 2; 1504, p. 2). An example of such an 
administrative control for minimizing the number of employees exposed 
to respirable crystalline silica would be to schedule high-exposure 
tasks to be conducted when others will not be in adjacent areas 
(Document ID 3583, Tr. 2385-2386).
    Commenters from the construction industry submitted comments on the 
regulated area option. Some of the comments were generally supportive 
(Document ID 2169, p. 4; 2177, Attachment B, p. 14; 2262, pp. 43-44; 
2339, p. 4). However, other stakeholders felt that OSHA's proposed 
requirements for regulated areas would be unworkable and infeasible in 
construction (e.g., Document ID 2116, Attachment 1, p. 13; 2183, pp. 1-
2; 2187, p. 5-6; 2269, p. 4; 2276, p. 5; 2319, pp. 89-90; 2323, p. 1; 
2338, p. 3; 2345, p. 3). They expressed serious concerns with the 
proposed provisions for establishing and limiting access to regulated 
areas, often citing challenges posed by constantly changing work 
activities, multiple employers on the worksite, lack of employer 
control in outside construction projects, the possibility of an entire 
worksite needing to be classified as a regulated area (on small 
worksites), and the prevalence of silica in the natural environment, 
particularly in certain regions of the country (e.g., Document ID 2116, 
pp. 13-14, 22, 27; 2183, pp. 1-2; 2319, p. 89; 2323, p. 1; 2210, 
Attachment 1, p. 7; 2187, pp. 5-6; 2246, p. 11; 2269, p. 22; 2296, p. 
26; 3230, p. 2). For example, ASA questioned a subcontractor's ability 
to control the environment on a multiemployer job site, stating:

. . . even if a trade contractor were to establish a regulated area, 
it may not be able to limit access or operations by individuals 
outside of its management or control, particularly in the absence of 
a representative of a general contractor or construction manager 
(Document ID 2187, p. 6).

    The Interlocking Concrete Pavement Institute indicated that other 
construction trade workers labor in the same area from 10 to 90 percent 
of the time, and that efforts by OSHA to restrict access among trades 
on a job site would result in chaos (Document ID 2246, p. 11). The LBA 
added that, although OSHA's proposed requirements might be suitable for 
a single-employer setting where working conditions are somewhat 
consistent, they were unworkable in the construction industry (Document 
ID 2269, p. 8).
    OSHA received feedback from employee representatives and public 
health advocates indicating support for a requirement that employers 
establish and limit access to areas where high exposures may occur in 
the construction industry (Document ID 2177, Attachment B, p. 14; 2371, 
Attachment 1, pp. 17-19; 3589, Tr. 4263; 4223, p. 102). For example, 
the Laborers Health and Safety Fund of North America argued that 
regulated areas are helpful because they provide a visible indicator 
that a hazardous area exists for employees in different trades who may 
be on the worksite but would not otherwise be aware of the potential 
for exposure to respirable crystalline silica in that area (Document ID 
3589, Tr. 4263). NIOSH supported the need to protect workers on a 
construction site from exposure via regulated areas and/or a written 
access control plan. NIOSH also noted the importance of competent 
persons and how they play an integral role in establishing regulated 
areas (Document ID 2177, Attachment B, pp. 8-10, 14).
    Several commenters representing public health organizations and 
unions opined that construction employers could implement regulated 
areas on construction sites without a great deal of difficulty 
(Document ID 3585, Tr. 3090-3091; 4234, Part 1, pp. 24-25). The 
American Industrial Hygiene Association (AIHA) suggested how an 
employer might determine whether a regulated area needs to be 
established:

    Utilization of the Table 1 as a compliance option when 
respirators are required means the surrounding area must be 
considered a regulated area or under an access control plan. This 
combined with the engineering controls can help address the common 
problem of adjacent workers being inadvertently exposed to silica 
particulates. The need for a regulated area or control plan would 
now be an objective determination by the competent person. This in 
turn would help identify workers or areas where inadvertent exposure 
may occur and consequently allow procedures to be implemented to 
prevent this (Document ID 2169, p. 4).

    Other commenters indicated that, to an extent, regulated areas 
already exist on construction sites. At the public hearings, the Mason 
Contractors Association of America provided testimony pointing out that 
a vast majority of masonry work is already carried out in restricted 
zones, and that access to these zones by other workers is limited. They 
noted that access to these restricted work zones was ultimately 
controlled by the general contractor (Document ID 3585, pp. 2933-2934). 
BCTD noted that Kevin Turner of Hunt Construction Group, testifying on 
behalf of CISC, indicated that contractors creating a hazard on 
construction worksites identify their work areas to avoid putting other 
workers at risk, and explained how different contractors on a multi-
employer site routinely establish exclusion zones to exclude other 
workers from hazardous areas. BCTD argued that there is no reason why 
such an approach would not work for areas with high silica exposure as 
well (Document ID 4223, p. 102-105). ASSE indicated that, while the 
organization recognized the potential value of establishing regulated 
areas where silica overexposures are anticipated, there may be valid, 
practical reasons for exempting short-term construction worksites from 
this requirement as long as alternative worker protections are in place 
(Document ID 3430, p. 3)
    After a review of these comments submitted on the proposed rule by 
construction industry stakeholders, OSHA concludes that a requirement 
for regulated areas is not appropriate for the construction standard. 
OSHA proposed to require regulated areas wherever an employee's 
exposure to respirable crystalline silica is, or can reasonably be 
expected to be, in excess of the PEL. However, OSHA expects that a 
majority of the regulated community in construction will implement the 
specified exposure control methods presented in paragraph (c) of the 
standard for construction (i.e., the controls listed in Table 1) for 
the purposes of reducing occupational exposure to respirable 
crystalline silica and to assure compliance with the standard. 
Employers who implement the specified exposure control methods 
presented in paragraph (c) of the standard for construction will not be 
required to assess employee exposures to respirable crystalline silica, 
and thus will not necessarily be aware of situations where employee 
exposures exceed the PEL. Furthermore, these employers who are not 
necessarily required to conduct an exposure assessment would thereby 
not have the data necessary to establish and demarcate the boundaries 
of regulated areas (i.e., the point at which exposures no longer exceed 
the PEL). Therefore,

[[Page 16779]]

most construction employers will not have an objective basis for 
establishing regulated areas.
    In addition, OSHA basis its decision not to require regulated areas 
in the standard for construction in part on its recognition that 
conditions at construction worksites present challenges to establishing 
regulated areas for respirable crystalline silica exposure due to the 
varied and changing nature of construction work. Various commenters 
representing construction interests expressed how factors such as 
environmental variability normally present in construction differ 
substantially from those typically found in general industry and 
maritime workplaces. These commenters noted that construction tasks are 
often of relatively short duration; they are commonly performed 
outdoors, sometimes under adverse environmental conditions; and they 
are normally performed at non-fixed workstations or worksites. These 
factors make establishment of regulated areas impractical for many 
construction tasks. Silica-generating tasks in construction often 
involve movement to different locations during the workday, and 
respirable crystalline silica may be subject to changes in wind 
currents, meaning that exposure patterns may frequently shift. 
Accordingly, in the typical construction project involving silica-
generating tasks, it is difficult to determine appropriate boundaries 
for regulated areas because the work and worksite are varied and 
subject to environmental influences (e.g., Document ID 2246, p. 11; 
2269, pp. 4, 9-10; 2289, pp. 6-7; 2309, p. 3; 2327, p. 20).
    OSHA finds the evidence of the particular and varying nature of 
construction work persuasive. Furthermore, the requirement for a 
competent person as part of the written exposure control plan 
requirements in paragraph (g)(4) of the standard for construction 
provides that a designated competent person on the worksite will have 
the responsibility to restrict access to work areas, where necessary, 
to limit exposures to respirable crystalline silica. OSHA concludes 
that this requirement will achieve the primary objectives of a 
regulated area.
    OSHA realizes that in some cases general industry work tasks and 
work environments may be comparable to those found in construction. 
Although no exceptions have been carved out of the requirement in the 
standard for general industry and maritime, where the general industry 
or maritime employer can show compliance is not feasible, regulated 
areas will not have to be established insofar as infeasibility is a 
complete defense to an OSHA citation. See United Steelworkers v. 
Marshall, 647 F.2d 1189 (D.C. Cir. 1980); Marshall v. West Point 
Pepperell, Inc., 588 F.2d 979 (5th Cir. 1979). As a general matter, 
however, OSHA's longstanding distinction between general industry 
(including, for these purposes, the maritime sector), on the one hand, 
and the construction sector, on the other hand, provides an appropriate 
line for delineating between those tasks where the employer generally 
is reasonably able to establish regulated areas where exposures to 
respirable crystalline silica exceed the PEL versus tasks where 
regulated areas are generally not practicable.
    ASTM E 1132-06 and ASTM E 2625-09 do not include requirements for 
regulated areas. However, both industry consensus standards indicate 
that workers should not work in areas where visible dust is generated 
from crystalline silica-containing materials without the use of 
respiratory protection, unless proven protective measures are used or 
sampling shows exposure is below the exposure limit (see Section 
4.4.3.1 in each standard) (Document ID 1466, p. 4; 1504, p. 3). OSHA 
considers the approach taken in its standard for construction to be 
consistent with the approach taken in the ASTM standards. OSHA further 
considers that the requirement for regulated areas in the standard for 
general industry and maritime better effectuates the purposes of the 
OSH Act because the establishment of regulated areas in those 
workplaces, where they are most effective, serves to limit the number 
of employees exposed and the level of exposure of employees who would 
otherwise be at significant risk of suffering adverse health effects 
from exposure to respirable crystalline silica. As explained above, 
regulated areas make employees aware of the presence of respirable 
crystalline silica at levels above the PEL and the need for protective 
measures, and serve to limit respirable crystalline silica exposure to 
as few employees as possible. Additionally, OSHA notes that the 
industry consensus standards addressing occupational exposure to 
respirable crystalline silica do not include requirements for 
protective clothing. The OSHA rule is consistent with the consensus 
standards in this respect also.

Methods of Compliance

    Paragraph (f)(1) of the standard for general industry and maritime 
(paragraph (d)(3)(i) of the standard for construction) establishes a 
hierarchy of controls that employers must use to reduce and maintain 
exposures to respirable crystalline silica to or below the permissible 
exposure limit (PEL) of 50 [mu]g/m\3\. The rule requires employers to 
implement engineering and work practice controls as the primary means 
to reduce exposure to the PEL or to the lowest feasible level above the 
PEL. In situations where engineering and work practice controls are not 
sufficient to reduce exposures to or below the PEL, employers are 
required to supplement these controls with respiratory protection, 
according to the requirements of paragraph (g) of the standard for 
general industry and maritime (paragraph (e) of the standard for 
construction).
    OSHA's long-standing hierarchy of controls policy was supported by 
many commenters including the National Institute for Occupational 
Safety and Health (NIOSH), the American Society of Safety Engineers 
(ASSE), the American Industrial Hygiene Association, the American 
Federation of Labor and Congress of Industrial Organizations (AFL-CIO), 
the American Public Health Association (APHA), the National Asphalt 
Pavement Association (NAPA), the National Utility Contractors 
Association, the American Road and Transportation Builders Association 
(ARTBA), and the International Safety Equipment Association (ISEA) 
(e.g., Document ID 1757, p. 4; 1771, p. 1; 1797, p. 5; 1800, p. 5; 
2106, p. 2; 2166, p. 3; 2173, p. 4; 2178, Attachment 1, pp. 3-4; 2181, 
p. 9; 2240, p. 2; 2256, Attachment 2, pp. 11-12; 2278, p. 3; 2313, p. 
6; 2315, p. 3; 2329, p. 5; 2336, p. 7; 2371, Attachment 1, p. 22; 2373, 
pp. 3-4; ; 3468, p. 3; 3516, p. 3; 3577, Tr. 791; 3578, Tr. 1044-1045; 
3579, Tr. 182-183; 3581, Tr. 1564, 1648-1651; 3583, Tr.2237, 2243-2244, 
2451, 2456; 3584, Tr. 2576-2577; 3955, Attachment 1, p. 2; 3585, Tr. 
3112; 3586, Tr. 3162, 3200; 3589, Tr. 4147; 1759; 4203, p. 4; 4204, pp. 
64-65; 4219, pp. 16, 20; 4223, p. 86; 4227, p. 1; 4233, Attachment 1, 
p. 14; 4235, p. 14). Tom Ward, a bricklayer and member of the 
International Union of Bricklayers and Allied Craftworkers (BAC) 
testified:

    [The hierarchy of controls] is the first thing we are supposed 
to do. Whenever feasible, eliminate the hazard. PPE is and always 
should be the last line of defense. Switching it is going backwards 
. . . (Document ID 3585, Tr. 3070).

    Many industry commenters, including trade associations, generally 
objected to OSHA's proposed application of the hierarchy of controls in 
the rule. These commenters included the U.S. Chamber of Commerce (the 
Chamber), Associated

[[Page 16780]]

Builders and Contractors, the Association of American Railroads (AAR), 
Battery Council International (BCI), the Motor and Equipment 
Manufacturers Association (MEMA), the Institute of Makers of Explosives 
(IME), the Association of Energy Service Companies, and the Precast/
Prestressed Concrete Institute (PCI) (e.g., Document ID 1728; 1992, pp. 
10-11; 2102, p. 2; 2130, pp. 1-2; 2151, p. 1; 2211, pp. 6-7; 2213, pp. 
3-4; 2276, p. 3; 2288, pp. 12-13;2289, p. 7; 2325, p. 2; 2326, p. 2; 
2344, p. 2; 2361, p. 3; 2366, p. 5; 4194, pp. 12-13). These commenters 
asked OSHA to reconsider its preference for engineering and work 
practice controls and permit the use of respiratory protection, such as 
powered air-purifying respirators (PAPRs), instead of engineering and 
work practice controls to reduce exposures to respirable crystalline 
silica to or below the PEL. For example, the Chamber urged OSHA to 
support

. . . new technology and policies favoring effective, comfortable, 
respirators and clean filtered air helmets, which provide full 
protection but are not favored by OSHA's outdated `hierarchy of 
control' policy (Document ID 4194, p. 4).

Similarly, the American Foundry Society (AFS) argued that:

    OSHA's preference for controls other than respirators is based 
on a policy that was adopted decades ago, and fails to take into 
account changes in respirator technology that have resulted in 
improved performance, improved reliability, improved worker 
acceptance, and increased protection (Document ID 3487, p. 25).

Greg Sirianni, an industrial hygienist testifying for the Chamber, 
commented that some respiratory protection, such as PAPRs, ``should not 
be looked at as mere respirators, but as microenvironmental engineering 
controls'' (Document ID 2364, p. 12). He described several studies 
demonstrating the effectiveness of PAPRs with helmets/hoods (Document 
ID 2364, pp. 6-7). He also referenced studies showing that PAPRs reduce 
physiological burdens, as well as provide increased comfort, ease of 
use, and improved communication, when compared to traditional air-
purifying respirators (Document ID 2364, pp. 8-10). Other industry 
commenters, including the National Association of Manufacturers (NAM), 
AFS, and National Mining Association, echoed Mr. Sirianni's conclusion 
about the effectiveness of PAPRs (Document ID 2211, pp. 6-7; 2379, 
Appendix 1, p. 49; 2380, Attachment 2, pp. 22-23; 3489, p. 5;). Peter 
Mark, Corporate Director of Safety, Health, and Environment at Grede 
Holdings, testified that some respirators, such as air-supplied 
helmets, can also provide eye and face protection (Document ID 3584, 
Tr. 2685-2686). The George Washington University Regulatory Studies 
Center argued that OSHA's hierarchy of controls eliminates the 
incentive to develop more effective, lower cost, and more comfortable 
respirators and ``distorts the development of new knowledge that could 
provide superior protection for employees'' (Document ID 1831, p. 15).
    Other commenters pointed to the disadvantages of engineering 
controls. The Construction Industry Safety Coalition (CISC), NAM, PCI, 
and AFS noted that engineering controls are subject to human error and 
maintenance concerns (Document ID 2319, p. 95; 2380, Attachment 2, p. 
22; 3487, p. 25; 3581, Tr. 1738, 1762; 3589, Tr. 4357). The Tile 
Roofing Institute (TRI), National Roofing Contractors Association 
(NRCA), National Association of Home Builders (NAHB), CISC, and NAM 
described situations where the use of engineering and work practice 
controls could present other hazards, such as falls (Document ID 2191, 
pp. 9-10; 2214, pp. 3-4; 2296, p. 28; 2319, p. 93; 3587, Tr. 3593-3594; 
4225, p. 2; 4226, p. 3). OSCO Industries (OSCO) commented that where 
ventilation requires all doors and windows to be closed, engineering 
controls can put physiological and psychological strain on employees 
(Document ID 1992, p. 10).
    NIOSH provided evidence that recent improvements in PAPRs have not 
eliminated all of their disadvantages. NIOSH cited several studies 
suggesting that psychological issues, medical disqualifications, 
communication impairment, hearing degradation, and visual impairment 
remained even for PAPRs (Document ID 4233, Attachment 1, pp. 17-20). 
NIOSH also noted that there are no maximum weight requirements for 
PAPRs, some of which can be fairly heavy (Document ID 4233, Attachment 
1, p. 18). When questioned about the use of PAPRs in the brick 
industry, Thomas Brown, the Director of Health and Safety at Acme Brick 
Company, testified that:

    No, we have not used [PAPRs]. And the reason why [is] it would 
be almost virtually impossible to wear those type[s] of respirators 
and perform the tasks that they are doing (Document ID 3577, Tr. 
752).

    No commenter representing employees or public health organizations 
agreed that PAPRs have improved to the point that they have become 
preferable to engineering controls. For example, when asked whether 
PAPRs should be viewed as an alternative to engineering controls and 
treated on the same level in the hierarchy of controls, Frank Hearl, 
Chief of Staff at NIOSH, testified that, ``. . . in terms of the PAPR 
and other respirators, it all sort of falls into the hierarchy of 
controls and suffers the same problems as the other respirators in that 
it doesn't control the entire environment'' (Document ID 3579, Tr. 
233). The Building and Construction Trades Department, AFL-CIO (BCTD) 
testified that PAPRs are not an adequate alternative given that they do 
not ``. . . control the hazards at the source for all workers'' 
(Document ID 3581, Tr. 1668-1669). Similarly, ISEA commented that ``. . 
. the association does not believe PAPRs can be used as engineering 
controls'' since they do not remove hazards from the workplace 
(Document ID 4227, p. 1).
    NIOSH, public health organizations, labor unions, individual 
employees, trade associations, public interest organizations and 
employers also provided additional evidence of the discomfort and 
difficulties experienced by employees who wear respirators (e.g., 
extreme temperatures, visibility restrictions, communication 
impairment, psychological issues, strain on respiratory and cardiac 
systems) (Document ID 1758; 2116, Attachment 1, p. 28; 2178, Attachment 
1, p. 4; 2181, pp. 9, 12; 2262, p. 26; 2314, p. 2; 2373, p. 4; 3571, 
Attachment 1, p. 2; 3577, Tr. 839-841; 3579, Tr. 183-184; 3580, Tr. 
1526-1527; 3582, Tr. 1872-1874, 1897, 1899-1901; 3583, Tr. 2434-2435; 
3585, Tr. 3112; 3586, Tr. 3174-3175, 3180, 3250, 3252-3253; 3587, Tr. 
3583-3584, 3637-3638; 4233, Attachment 1, pp. 18-19; 4235, p. 12). 
Other commenters, including NIOSH, the International Union of Operating 
Engineers (IUOE), the Brick Industry Association, TRI, NAPA, ARTBA, the 
Interlocking Concrete Pavement Institute, Black Roofing, the National 
Tile Contractors Association, Acme Brick, and iQ Power Tools also 
described how respirator use can exacerbate various safety and health 
threats to employees, such as trips, falls, ``struck by'' hazards, saw 
hazards, and heat stress (Document ID 2262, p. 25; 2293; 3529, p. 2; 
3577, Tr. 714, 750-752; 3583, Tr. 2170, 2237, 2372, 2435-2437; 3586, 
Tr. 3341, 3406; 3587, Tr. 3583-3584, 3594; 3589, Tr. 4373; 4225, p. 6; 
4233, Attachment 1, p. 18; 4234, Part 1 and Part 2, pp. 30-31; 4235, p. 
12). IUOE, the Laborers' Health and Safety Fund of North America 
(LHSFNA), and Arch Masonry further noted that reliance on respirators 
to protect

[[Page 16781]]

employees from exposures to respirable crystalline silica could end the 
careers of employees who cannot pass the medical evaluation, but can do 
the work (Document ID 2262, p. 27; 2292, p. 4; 3587, Tr. 3656-3567; 
3589, Tr. 4274-4275).
    In addition, NIOSH and other public health professionals described 
how respirators are more prone to misuse or other human error, as they 
depend on human behavior to achieve beneficial results (Document ID 
2374, Attachment 1, pp. 5-6; 3577, Tr. 848-849; 3579, Tr. 183-184). On 
the other hand, engineering controls are easier to monitor and 
maintain. As Dr. Celeste Monforton testified:

    It is illogical to suggest that diligently meeting all the 
laborious requirements necessary for an effective respiratory 
protection program for a whole crew of employees is easier than 
ensuring that a handful of silica-generating pieces of equipment are 
maintained (Document ID 3577, Tr. 849).

    Various individuals and organizations detailed the lack of adequate 
fit testing and respiratory protection programs in practice, which can 
significantly impact respirator effectiveness. These included Dr. 
Monforton, ASSE, the National Council of La Raza, the National 
Consumers League (NCL), APHA, the National Council for Occupational 
Safety and Health, NRCA, and Arch Masonry as well as workers, including 
James Schultz and Allen Schultz (Document ID 2166, p. 3; 2173, p. 5; 
2178, Attachment 1, pp. 3-4; 2373, pp. 3-4; 3577, Tr. 848-849; 3578, 
Tr. 1040-1041, 1042-1043; 3586, Tr. 3161, 3213-3214, 3236-3237, 3253-
3254; 3587, Tr. 3625, 3680-3681; 3955, Attachment 1, p. 2). Workers, 
including James Schultz, Jonass Mendoza, Santiago Hernandez, Juan Ruiz, 
Norlan Trejo and Jose Granados described their negative experiences 
with respirator use, including the lack of fit testing, training, and 
proper maintenance (Document ID 3571, Attachment 2, p. 3; 3571, 
Attachment 3, p. 2; 3571, Attachment 5, p. 1; 3571, Attachment 7, p. 1; 
3583, Tr. 2487; 3586, Tr. 3201-3202;). Dr. Laura Welch, representing 
BCTD, testified that in her experience, respiratory protection does not 
prevent employees from developing lung disease, but that engineering 
controls are effective (Document ID 3581, Tr. 1648-1649).
    Further, NIOSH, labor organizations (e.g., LHSFNA, the 
International Association of Sheet Metal, Air, and Rail Transportation 
Workers, the Operative Plasterers' and Cement Masons' International 
Association, the International Union of Painters and Allied Trades 
(IUPAT), the United Union of Roofers, Waterproofers, and Allied 
Workers, BAC, the United Steelworkers, BCTD, and AFL-CIO), public 
health organizations (e.g., APHA), public interest organizations (e.g., 
the Center for Biological Diversity, the Center for Effective 
Government, and NCL), and individual workers described how limiting 
exposure to respirable crystalline silica at its source through 
engineering and work practice controls best protects employees involved 
in dust-generating operations, as well as other employees and the 
public from these exposures (e.g., Document ID 2178, Attachment 1, p. 
4; 2253, pp. 1-2; 2329, p. 4; 2373, p. 4; 2374, Attachment 1, pp. 5-6; 
3516, p. 3; 3579, Tr. 184-185, 233; 3581, Tr. 1590, 1593-1594, 1649-
1651,1669, 1708-1709; 3582, Tr. 1878-1879, 1881-1883; 3583, Tr. 2455-
2456; 3584, Tr. 2578-2579; 3585, Tr. 3067-3069; 4204, pp. 68, 72-74; 
3589, Tr. 4232-4233; 4223, pp. 86-87; 4233, Attachment 1, pp. 11-14). 
For example, LHSFNA noted that using controls on jackhammers, chipping 
guns, hand-held grinders, and drywall sanders can reduce exposures to 
nearby laborers (Document ID 2253, pp. 1-2). Norlan Trejo testified 
that when cutting ceramic and granite, wet cutting helps protect both 
the employee and bystanders (Document ID 3583, Tr. 2455-2456). Sean 
Barrett, a terrazzo worker, testified that grinding floors in the 
terrazzo industry exposes everyone on the worksite if controls are not 
used:

    Every other trade has to walk through the cloud [of dust] to get 
in and out of the building to use the outhouses or to go to the 
coffee truck or even go home at the end of the day . . . [T]hey have 
no choice but to walk through the dust (Document ID 3585, Tr. 3068).

Additionally, James Schultz, a former foundry employee from the 
Wisconsin Coalition for Occupational Safety and Health, provided 
testimony about how the lack of engineering controls creates dusty 
conditions that can lead to other hazards. He described how dusty 
conditions in a foundry led to incidents where employees were struck by 
forklifts (Document ID 3586, Tr. 3242-3243).
    Some of the same industry commenters advocating for the use of 
PAPRs in place of engineering controls have acknowledged the importance 
of engineering controls to protect employees from exposures to 
respirable crystalline silica. For example, AFS, in its Guide for 
Selection and Use of Personal Protective Equipment and Special Clothing 
for Metalcasting Operations, describes the hierarchy of controls as the 
basis for choosing strategies for protecting employers from exposures 
to airborne contaminants. The guide concludes that air-supplied hoods 
and PAPRs are important options when choosing respiratory or personal 
protection, but does not support using these in lieu of engineering 
controls (Document ID 2379, Appendix 6). NAM noted that they were not 
opposed to using engineering controls where they are feasible and 
effective (Document ID 3581, Tr. 1753). Greg Sirianni, an expert for 
the Chamber, testified that:

. . . there are obviously benefits to engineering controls, and by 
all means I want the use of engineering controls when they are 
possible. And in certain work environments . . . you need to have 
something that can protect all workers in all scenarios, and 
engineering controls are good for most cases, but there are a lot of 
workers out there that need [PAPRs], and I really recommend their 
use (Document ID 3578, Tr. 1104-1105).

Other industry groups provided additional evidence that the hierarchy 
of controls is embraced and applied in practice. For example, Wayne 
D'Angelo of the American Petroleum Institute (API) testified that the 
organization supports the traditional use of the hierarchy of controls 
to protect employees (Document ID 3589, Tr. 4065). The National 
Industrial Sand Association (NISA) has built the hierarchy of controls 
into its Practical Guide to an Occupational Health Program for 
Respirable Crystalline Silica (Document ID 1965, Attachment 2, pp. vii, 
44). The National Stone, Sand, and Gravel Association's occupational 
health program, which is based on NISA's program, also supports the 
industrial hygiene hierarchy of controls (Document ID 3583, Tr. 2312).
    OSHA concludes that requiring primary reliance on engineering 
controls and work practices is necessary and appropriate because 
reliance on these methods is consistent with good industrial hygiene 
practice, and with the Agency's experience in ensuring that employees 
have a healthy workplace. The Agency finds that engineering controls: 
(1) Control crystalline silica-containing dust particles at the source; 
(2) are reliable, predictable, and provide consistent levels of 
protection to a large number of employees; (3) can be monitored 
continually and relatively easily; and (4) are not as susceptible to 
human error as is the use of personal protective equipment. The use of 
engineering controls to prevent the release of silica-containing dust 
particles at the source also minimizes the silica exposure of other 
employees in surrounding work areas who are not directly involved in 
the task that is generating the dust, and

[[Page 16782]]

may not be wearing respirators. This issue of secondary exposures to 
other laborers and bystanders is especially of concern at construction 
sites (e.g., Document ID 2177, Attachment B, pp. 14-15; 2329, p. 4; 
2319, p. 28, 3581, Tr. 1587-1588).
    Under the hierarchy of controls, respirators can be another 
effective means of protecting employees from exposure to air 
contaminants. However, to be effective, respirators must be 
individually selected, fitted and periodically refitted, 
conscientiously and properly worn, regularly maintained, and replaced 
as necessary. In many workplaces, these conditions for effective 
respirator use are difficult to achieve. The absence of any one of 
these conditions can reduce or eliminate the protection the respirator 
provides to some or all of the employees. For example, certain types of 
respirators require the user to be clean shaven to achieve an effective 
seal where the respirator contacts the employee's skin. Failure to 
ensure a tight seal due to the presence of facial hair compromises the 
effectiveness of the respirator.
    Respirator effectiveness ultimately relies on the good work 
practices of individual employees. In contrast, the effectiveness of 
engineering controls does not rely so heavily on actions of individual 
employees. Engineering and work practice controls are capable of 
reducing or eliminating a hazard from a worksite, while respirators 
protect only the employees who are wearing them correctly. Furthermore, 
engineering and work practice controls permit the employer to evaluate 
their effectiveness directly through air monitoring and other means. It 
is considerably more difficult to directly measure the effectiveness of 
respirators on a regular basis to ensure that employees are not 
unknowingly being overexposed. OSHA therefore continues to consider the 
use of respirators to be the least satisfactory approach to exposure 
control.
    In addition, use of respirators in the workplace presents other 
safety and health concerns. Respirators can impose substantial 
physiological burdens on employees, including the burden imposed by the 
weight of the respirator; increased breathing resistance during 
operation; limitations on auditory, visual, and olfactory sensations; 
and isolation from the workplace environment. Job and workplace factors 
such as the level of physical work effort, the use of protective 
clothing, and temperature extremes or high humidity can also impose 
physiological burdens on employees wearing respirators. These stressors 
may interact with respirator use to increase the physiological strain 
experienced by employees.
    Certain medical conditions can compromise an employee's ability to 
tolerate the physiological burdens imposed by respirator use, thereby 
placing the employee wearing the respirator at an increased risk of 
illness, injury, and even death. These medical conditions include 
cardiovascular and respiratory diseases (e.g., a history of high blood 
pressure, angina, heart attack, cardiac arrhythmias, stroke, asthma, 
chronic bronchitis, emphysema), reduced pulmonary function caused by 
other factors (e.g., smoking or prior exposure to respiratory hazards), 
neurological or musculoskeletal disorders (e.g., epilepsy, lower back 
pain), and impaired sensory function (e.g., a perforated ear drum, 
reduced olfactory function). Psychological conditions, such as 
claustrophobia, can also impair the effective use of respirators by 
employees and may also cause, independent of physiological burdens, 
significant elevations in heart rate, blood pressure, and respiratory 
rate that can jeopardize the health of employees who are at high risk 
for cardiopulmonary disease (see 63 FR 1152, 1208-1209 (1/8/98)).
    In addition, safety problems created by respirators that limit 
vision and communication must always be considered. In some difficult 
or dangerous jobs, effective vision or communication is vital. Voice 
transmission through a respirator can be difficult, annoying, and 
fatiguing. In addition, movement of the jaw in speaking can cause 
leakage, thereby reducing the efficiency of the respirator and 
decreasing the protection afforded the employee. Skin irritation can 
result from wearing a respirator in hot, humid conditions. Such 
irritation can cause considerable distress to employees and can cause 
employees to refrain from wearing the respirator, thereby rendering it 
ineffective.
    These potential burdens placed on employees by the use of 
respirators were acknowledged in OSHA's revision of its respiratory 
protection standard, and are the basis for the requirement (29 CFR 
1910.134(e)) that employers provide a medical evaluation to determine 
the employee's ability to wear a respirator before the employee is fit 
tested or required to use a respirator in the workplace (see 63 FR at 
1152). Although experience in industry shows that most healthy 
employees do not have physiological problems wearing properly chosen 
and fitted respirators, nonetheless common health problems can cause 
difficulty in breathing while an employee is wearing a respirator.
    While OSHA acknowledges that certain types of respirators, such as 
PAPRs, may lessen problems associated with breathing resistance and 
skin discomfort, they do not eliminate them. OSHA concludes that 
respirators do not provide employees with a level of protection that is 
equivalent to engineering controls, regardless of the type of 
respirator used. It is well-recognized that certain types of 
respirators are superior to other types of respirators with regard to 
the level of protection offered, or impart other advantages like 
greater comfort. OSHA has evaluated the level of protection provided by 
different types of respirators in the Agency's Assigned Protection 
Factors rulemaking (68 FR 34036 (06/06/03)). Even in situations where 
engineering controls are not sufficiently effective to reduce exposure 
levels to or below the PEL, the reduction in exposure levels benefits 
employees by reducing the required protection factor of the respirator, 
which provides a wider range of options in the type of respirators that 
can be used. For example, for situations in which dust concentrations 
are reduced through use of engineering controls to levels that are less 
than ten times the PEL, employers would have the option of providing 
approved half-mask respirators with an assigned protection factor (APF) 
of 10 that may be lighter and easier to use when compared with full-
facepiece respirators.
    All OSHA substance-specific health standards have recognized and 
required employers to observe the hierarchy of controls, favoring 
engineering and work practice controls over respirators. OSHA's PELs, 
including the previous PELs for respirable crystalline silica, also 
incorporate this hierarchy of controls. The Agency's adherence to the 
hierarchy of controls has been successfully upheld by the courts (see 
Section II, Pertinent Legal Authority for further discussion of these 
cases). In addition, the industry consensus standards for crystalline 
silica (ASTM E 1132-06, Standard Practice for Health Requirements 
Relating to Occupational Exposure to Respirable Crystalline Silica, and 
ASTM E 2625-09, Standard Practice for Controlling Occupational Exposure 
to Respirable Crystalline Silica for Construction and Demolition 
Activities) incorporate the hierarchy of controls. NRCA also pointed 
out that the ANSI Z10, Standard for Occupational Health and Safety 
Management Systems, supports the hierarchy of controls (Document ID 
2214, p. 3) and Dr. Celeste Monforton noted that the

[[Page 16783]]

hierarchy of controls has been followed and adopted by safety and 
health regulatory agencies around the world, including Safe Work 
Australia, the country's tripartite health and safety body, and the 
Canadian Province of Ontario's Health and Safety Agency (Document ID 
3577, Tr. 847-848).
    As explained in Section II, Pertinent Legal Authority, the very 
concept of technological feasibility for OSHA standards is grounded in 
the hierarchy of controls. The courts have clarified that a standard is 
technologically feasible if OSHA proves a reasonable possibility,

. . . within the limits of the best available evidence . . . that 
the typical firm will be able to develop and install engineering and 
work practice controls that can meet the PEL in most of its 
operations (United Steelworkers v. Marshall, 647 F.2d 1189, 1272 
(D.C. Cir. 1980)).

Allowing use of respirators instead of engineering and work practice 
controls would be a significant departure from this framework for 
evaluating the technological feasibility of a PEL.
    While labor groups were opposed to any exemptions from the 
hierarchy of controls (Document ID 3586, Tr. 3235-3237), industry 
commenters, including both individual employers and trade associations, 
urged OSHA to consider making exemptions to the hierarchy in various 
situations. Commenters, including the Edison Electric Institute (EEI), 
Dal-Tile, the Glass Association of North America (GANA), the Tile 
Council of North America, the Non-Ferrous Founders' Society (NFFS), 
PCI, and the Chamber, argued that employers need flexibility to 
determine when enough engineering controls have been added and when 
respirators can be used (Document ID 2147, p. 3; 2215, p. 6; 2276, p. 
6; 2357, pp. 25-26; 2363, p. 4; 3491, p. 4; 3576, Tr. 466; 3589, Tr. 
4364). NAM echoed this, arguing that employers will never know when or 
if they are in compliance with the requirement to incorporate all 
feasible engineering and work practice controls and the Agency should 
thus base its requirements on objective criteria, while allowing 
flexibility to achieve compliance (Document ID 3581, Tr. 1738). Lapp 
Insulators, the Indiana Manufacturing Association, Murray Energy 
Corporation, BCI, Rheem Manufacturing Company, MEMA, IME, CISC, AFS, 
NFFS, and NAM urged OSHA to permit the use of respirators to satisfy 
the obligation to control exposures where feasible engineering and work 
practice controls are insufficient to bring exposure levels to or below 
the PEL (Document ID 1801, pp. 3-4; 2102, p. 2; 2130, pp. 1-2; 2151, p. 
1; 2213, pp. 3-4; 2319, p. 95; 2325, p. 2; 2326, p. 2; 2361, p. 3; 
2380, Appendix 2, pp. 22-23; 3486, p. 2; 3491, pp. 4-5; 3581, Tr. 1752-
1753; 4226, p. 2). This concern was echoed by other commenters who 
encouraged OSHA to permit the use of respirators in industries using 
large amounts of crystalline silica (e.g., oil and gas operations where 
hydraulic fracturing is conducted), where engineering controls alone 
would not be likely to reduce exposures to or below the PEL (Document 
ID 2283, p. 3; 3578, Tr. 1090-1091).
    OSHA disagrees. Instead, the Agency considers engineering controls 
to be the most effective method of protecting employees and allows 
respiratory protection only after all feasible engineering controls and 
work practices have been implemented or where such controls have been 
found infeasible. If an employer has adopted all feasible engineering 
controls, and no other feasible engineering controls are available, the 
rule would permit the use of respirators. On the other hand, if 
feasible engineering controls are available that would reduce 
respirable crystalline silica exposures that exceed the PEL, then these 
controls are required. Thus, OSHA has concluded these engineering 
controls better protect employees.
    Commenters, including CISC and OSCO, urged OSHA to permit the use 
of respirators for short duration, intermittent, or non-routine tasks 
(Document ID 1992, pp. 3, 5; 2319, pp. 95, 115; 3580, Tr. 1463-1464). 
Others, such as the Glass Packaging Institute (GPI) and NAM, argued 
that OSHA should permit the use of respirators for maintenance 
activities (Document ID 2290, pp. 2, 3; 2380, Attachment 2, pp. 14-15; 
3493, pp. 2-3). Verallia North America recommended that respirators be 
allowed in all refractory repairs (Document ID 3584, Tr. 2848).
    Where OSHA requires respirator use in this rule, the requirement is 
tied to expected or recorded exposures above the PEL, not categorically 
to specific operations or tasks per se. The rule permits the use of 
respirators where exposures exceed the PEL during tasks for which 
engineering and work practice controls are not feasible. Some tasks, 
such as certain maintenance and repair activities, may present a 
situation where engineering and work practice controls are not 
feasible. For example, GPI noted that respirators are needed to address 
failures of any conveyance system (elevators, conveyors, or pipes), 
failures of dust collecting bag systems, or section head failures at 
glass plant facilities (Document ID 3493, p. 3). OSCO described how 
engineering controls are not feasible for cupola (furnace) repair work 
and baghouse maintenance activities (Document ID 1992, pp. 3, 5). The 
Agency agrees that for tasks, such as certain maintenance and repair 
activities, where engineering and work practice controls are not 
feasible, the use of respirators is permitted.
    The Chamber and the American Subcontractors Association (ASA) 
suggested that the hierarchy of controls is not appropriate for silica 
exposures in construction workplaces (Document ID 2187, p. 6; 2283, p. 
3). While ASSE generally supported the hierarchy of controls, it 
acknowledged that there might be practical issues with implementation 
on short-term construction worksites (Document ID 2339, p. 4). More 
specifically, the Mason Contractors Association of America and Holes 
Incorporated urged OSHA to consider the approach taken by the ASTM 
standard for the construction industry (ASTM E 2625-09), which provides 
an exception to the hierarchy for brief, intermittent silica generating 
tasks of 90 minutes or less per day (Document ID 3580, Tr. 1453; 3585, 
Tr. 2882). Conversely, BCTD argued that even for silica dust-generating 
tasks of short duration where respiratory protection is employed, a 
failure to employ engineering controls could result in dangerous 
exposures (Document ID 4219, p. 17). They contended that:

    There is no evidence in the record that exposures of only 90 
minutes a day pose a lower risk of harm, such that respirators would 
provide sufficient protection. Moreover . . . the industry failed to 
prove that it is infeasible--or even difficult--to use engineering 
controls in most silica-generating tasks (Document ID 4223, p. 88).

    OSHA finds, as discussed above, that primary reliance on 
respirators to protect employees is inappropriate when feasible 
engineering and work practice controls are available. This is as true 
for the construction industry, as it is for other industries with 
respirable crystalline silica exposures. Even where employees are 
conducting intermittent silica generating tasks for 90 minutes or less 
per day, if the exposures are above the PEL and feasible engineering 
and work practice controls are available, they must be applied. 
Further, although an exemption for employees conducting silica 
generating tasks for 90 minutes or less per day is included in the ASTM 
standard for the construction industry, the standard also includes the 
hierarchy of controls, as well as task-based methods of compliance 
based on engineering and work practice controls

[[Page 16784]]

that are feasible and available for many construction tasks (ASTM E 
2625-09). This approach is consistent with the specified exposure 
control methods for construction in paragraph (c)(1) described in the 
summary and explanation of Specified Exposure Control Methods. OSHA 
concludes that requiring the use of all feasible engineering and work 
practice controls in the construction industry, even for tasks of short 
duration generating respirable crystalline silica, is reasonably 
necessary and appropriate to protect employees from exposures to 
respirable crystalline silica.
    AFS, NISA, GANA, EEI, the North American Insulation Manufacturers 
Association (NAIMA), and the Asphalt Roofing Manufacturers Association 
urged OSHA to consider allowing employers to use respirators to achieve 
compliance for operations where exposures exceed the PEL for 30 days or 
less per year (Document ID 4229, p. 11; 2195, pp. 7, 38-39; 2215, pp. 
9-10; 2291, pp. 2, 18; 2348, Attachment 1, pp. 17, 26-28, 40; 2357, p. 
26; 2379, Appendix 1, pp. 48, 68-69; 3487, pp. 22-23). Similarly, NAM 
proposed that OSHA could establish a maximum number of days a year when 
respirators can be used in place of engineering controls (Document ID 
2380, Attachment 2, pp. 24-25).
    Many of the examples mentioned by the commenters supporting this 
exemption described maintenance and repair activities, such as baghouse 
cleaning and furnace rebuilds. As discussed above, some tasks, such as 
certain maintenance and repair activities, may present a situation 
where engineering and work practice controls are not feasible. OSHA 
agrees that, for tasks of this nature where engineering and work 
practice controls are not feasible, the use of respirators is 
permitted. Permitting employers to use respirators instead of feasible 
engineering and work practice controls for exposures occurring for 30 
days or less per year does not best effectuate the purpose of the 
rule--to protect employees from exposures to respirable crystalline 
silica. Thus, the Agency concludes that the hierarchy of controls is 
appropriate whenever feasible engineering and work practice controls 
are available.
    The American Composite Manufacturers Association suggested that 
small businesses be exempt from the hierarchy of controls (Document ID 
3588, Tr. 3933-3936). Bret Smith urged OSHA to allow small entities to 
use respiratory protection temporarily to allow time to prepare for the 
costs of implementation (Document ID 2203). OSHA does not agree that 
there should be a distinction between the protection employees receive 
in a small business or a large business. Protecting the safety and 
health of employees is part of doing business. Thus, exposures to 
respirable crystalline silica above the PEL, wherever they occur, must 
first be controlled using all feasible engineering and work practice 
controls available, before turning to respiratory protection. For the 
reasons previously discussed, implementing and maintaining a 
comprehensive respiratory protection program is a considerable 
undertaking for many employers, and likely even more so for small 
businesses. If employers are unable to properly train and fit employees 
and maintain the equipment, respirators will not effectively protect 
employees from exposures to respirable crystalline silica.
    NAM proposed that OSHA adopt language to allow respirators to be 
used when exposures are below a specified level:

    Where airborne exposures to RCS on a time-weighted-average basis 
are below XX milligrams per cubic meter, employers may require the 
use of respirators in accordance with the requirements of 1910.134. 
Where exposures exceed this level, employers are required to adopt 
engineering and administrative controls to reduce exposures 
(Document ID 2380, Attachment 2, pp. 24-25).

They specifically provided the example of 5 mg/m\3\ (i.e., 5,000 [mu]g/
m\3\), the respirable dust PEL, which would permit the use of 
respirators that provide a protection factor of 100 to achieve 
compliance with the PEL of 50 [mu]g/m\3\.
    As discussed above, this approach is in conflict with the concept 
of technological feasibility for OSHA standards. Technological 
feasibility is determined based on the ability of a typical firm to 
develop and install engineering controls and work practice controls 
that can meet the PEL without regard to the use of respirators. The 
approach advanced by NAM would permit the use of respirators to achieve 
the PEL, even where exposures reached 100 times the PEL. If 
technological feasibility were based solely on the ability of 
respirators to meet the PEL, OSHA could determine that a much lower PEL 
would indeed be feasible. Further, a failure of respiratory protection 
in situations where exposures reach 100 times the PEL could result in 
extremely dangerous exposures.
    Therefore, OSHA rejects the various comments recommending upsetting 
the long-established hierarchy of controls. Because engineering and 
work practice controls are capable of reducing or eliminating a hazard 
from the workplace, while respirators protect only the employees who 
are wearing them and depend on the selection and maintenance of the 
respirator and the actions of employees, OSHA holds to the view that 
engineering and work practice controls offer more reliable and 
consistent protection to a greater number of employees, and are 
therefore preferable to respiratory protection. Thus, the Agency 
continues to conclude that engineering and work practice controls 
provide a more protective first line of defense than respirators and 
must be used first when feasible.
    Engineering controls. The engineering controls that are required by 
the standard can be grouped into four categories: (1) Substitution; (2) 
isolation; (3) ventilation; and (4) dust suppression. Depending on the 
sources of crystalline silica dust and the operations conducted, a 
combination of control methods may reduce silica exposure levels more 
effectively than a single method.
    Substitution refers to the replacement of a toxic material with 
another material that reduces or eliminates the harmful exposure. OSHA 
considers substitution to be an ideal control measure if it replaces a 
toxic material in the work environment with a non-toxic material, thus 
eliminating the risk of adverse health effects.
    As indicated in Chapter IV of the Final Economic Analysis and Final 
Regulatory Flexibility Analysis (FEA), employers use substitutes for 
crystalline silica in a variety of operations. For example, some 
employers use substitutes in abrasive blasting operations, repair and 
replacement of refractory materials, operations performed in foundries, 
and in the railroad transportation industry. Commenters, such as NIOSH, 
John Adams, Vice President of the American Federation of Government 
Employees Local 2778, Kyle Roberts, and the National Automobile Dealers 
Association (NADA) also identified several situations where substitute 
materials and products were available or used in place of silica-
containing products, including: The use of plastic curbs in place of 
concrete curbs to repair a highway overpass; the use of materials 
containing aluminum oxide instead of crystalline silica in dental labs; 
the use of aluminum pellets instead of sand in hydraulic fracturing 
operations; the availability of silica-free OEM and auto-refinish paint 
systems; and the availability of silica-free body fillers and silica-
free abrasives for auto

[[Page 16785]]

body repair work (Document ID 1763, p. 2; 1800, p. 5; 2177, Attachment 
B, pp. 37-38; 2358, p. 4).
    Commenters also identified many situations where no substitute 
materials and products were available to replace silica-containing 
materials and products. For example, Grede Holdings and AFS noted that 
there were no substitutes for sand for most foundry applications 
(Document ID 2298, p. 2; 2379, Appendix 1, pp. 14-16; 3486, p. 4). The 
General Contractors Association of New York, ASA, CISC, and NAHB noted 
that the construction industry cannot select alternate materials to 
avoid silica exposure, since nearly all construction materials and 
products contain silica (Document ID 2187, p. 6; 2314, pp. 1-2; 2296, 
pp. 7, 35; 2319, pp. 93-34). AAR and the American Short Line and 
Regional Railroad Association noted that substitute ballast materials 
with lower silica content cannot be used because they introduce safety 
hazards for employees and the public (Document ID 2366, pp. 5-6). GANA 
and NAIMA noted that silica is indispensable to the flat glass industry 
(Document ID 2215, p. 5; 2348, Attachment 1, pp. 8-10). NAM noted that 
viable alternatives of lower silica content are not available for some 
products made by their members (Document ID 3581, Tr. 1728). The 
Porcelain Enamel Institute noted that there are no proven replacements 
for mill-added crystalline silica for wet-applied enamel systems, given 
that the technical advantages offered by silica cannot be practically 
and economically achieved with other materials (Document ID 2281, p. 
3).
    The American College of Occupational and Environmental Medicine 
(ACOEM), the Mount Sinai-Irving J. Selikoff Centers for Occupational 
and Environmental Medicine, and Samantha Gouveia urged OSHA to more 
explicitly encourage the use of substitution where feasible (Document 
ID 1771, p. 1; 2080, pp. 4-5; 2208).
    Commenters also expressed concerns about the safety of substitutes 
(Document ID 2080, pp. 4-5; 2187, p. 6; 2278, pp. 3-4). ACOEM suggested 
that OSHA only endorse the use of substitutes when they have been 
demonstrated to be safe in short- and long-term inhalation toxicology 
studies and urged OSHA to request that NIOSH conduct a periodic 
assessment that evaluates substitutes to determine which ones have been 
found to be safe based upon results of inhalation toxicity and 
epidemiologic studies (Document ID 2080, pp. 4-5). Dr. George 
Gruetzmacher, an industrial hygiene engineer, urged OSHA to encourage 
the use of alternative materials to silica when feasible, but only when 
the substitute has been demonstrated to be safe in short- and long-term 
inhalation toxicology studies or to prohibit the substitution of 
materials which have not been demonstrated to be less toxic by 
inhalation (Document ID 2278, pp. 3-4).
    While OSHA finds that substitution can be an ideal control measure 
in certain circumstances, the Agency recognizes that this approach may 
not be feasible or safer in many others. Because some alternatives to 
silica or silica-containing materials may present health risks, OSHA is 
not implying that any particular alternative is an appropriate or safe 
substitute for silica. In its technological feasibility analyses, the 
Agency identified information about situations where substitution may 
be an available control strategy. OSHA strongly encourages employers to 
thoroughly evaluate potential alternatives, where available, to 
determine if a substitute can mitigate employees' exposure to 
respirable crystalline silica without posing a greater or new 
significant hazard to employees. Additionally, when substituting, 
employers must comply with Section 5(a)(1) of the OSH Act (29 U.S.C. 
654(a)(1)), which prohibits occupational exposure to ``recognized 
hazards that are causing or are likely to cause death or serious 
physical harm,'' and with applicable occupational safety and health 
standards. For example, with respect to chemical hazards, OSHA's hazard 
communication standard imposes specific requirements for employee 
training, safety data sheets, and labeling (see 29 CFR 1910.1200).
    Isolation, i.e., separating workers from the source of the hazard, 
is another effective engineering control employed to reduce exposures 
to crystalline silica. Isolation can be accomplished by either 
containing the hazard or isolating workers from the source of the 
hazard. For example, to contain the hazard, an employer might install a 
physical barrier around the source of exposure to contain a toxic 
substance within the barrier. Isolating the source of a hazard within 
an enclosure restricts respirable dust from spreading throughout a 
workplace and exposing employees who are not directly involved in dust-
generating operations. Or, alternatively, an employer might isolate 
employees from the hazard source by placing them in a properly 
ventilated cab or at some distance from the source of the respirable 
crystalline silica exposure.
    Ventilation is another engineering control method used to minimize 
airborne concentrations of a contaminant by supplying or exhausting 
air. Two types of systems are commonly used: Local exhaust ventilation 
(LEV) and dilution ventilation. LEV is used to remove an air 
contaminant by capturing it at or near the source of emission, before 
the contaminant spreads throughout the workplace. Dilution ventilation 
allows the contaminant to spread over the work area but dilutes it by 
circulating large quantities of air into and out of the area. 
Consistent with past recommendations such as those included in the 
chromium (VI) standard, OSHA prefers the use of LEV systems to control 
airborne toxics because, if designed properly, they efficiently remove 
contaminants and provide for cleaner and safer work environments.
    Dust suppression methods are generally effective in controlling 
respirable crystalline silica dust, and they can be applied to many 
different operations such as material handling, rock crushing, abrasive 
blasting, and operation of heavy equipment (Document ID 1147). Dust 
suppression can be accomplished by one of three systems: Wet dust 
suppression, in which a liquid or foam is applied to the surface of the 
dust-generating material; airborne capture, in which moisture is 
dispensed into a dust cloud, collides with particles, and causes them 
to drop from the air; and stabilization, which holds down dust 
particles by physical or chemical means (lignosulfonate, calcium 
chloride, and magnesium chloride are examples of stabilizers).
    The most common dust suppression controls are wet methods (see 
Chapter IV of the FEA). Water is generally an inexpensive and readily 
available resource and has been proven an efficient engineering control 
method to reduce exposures to airborne crystalline silica-containing 
dust. Dust, when wet, is less able to become or remain airborne.
    Work practice controls. Work practice controls systematically 
modify how employees perform an operation, and often involve employees' 
use of engineering controls. For crystalline silica exposures, OSHA's 
technological feasibility analysis shows that work practice controls 
are generally applied complementary to engineering controls, to adjust 
the way a task is performed (see Chapter IV of the FEA). For work 
practice controls to be most effective, it is essential that employees 
and supervisors are trained to be fully aware of the exposures 
generated by relevant workplace activities and the impact of the 
engineering controls installed. Work practice controls are preferred 
over the use of personal protective equipment, since work practice 
controls can address

[[Page 16786]]

the exposure of silica at the source of emissions, thus protecting 
nearby employees.
    Work practice controls can also enhance the effects of engineering 
controls. For example, to ensure that LEV is working effectively, an 
employee would position the LEV equipment so that it captures the full 
range of dust created, thus minimizing silica exposures. For many 
operations, a combination of engineering and work practice controls 
reduces silica exposure levels more effectively than a single control 
method.
    The requirement to use engineering and work practice controls is 
consistent with ASTM E 1132-06 and ASTM E 2625-09, the national 
consensus standards for controlling occupational exposure to respirable 
crystalline silica in general industry and in construction, 
respectively. Each of these standards has explicit requirements for the 
methods of compliance to be used to reduce exposures below exposure 
limits. These voluntary standards specifically identify several 
controls, which include use of properly designed engineering controls 
such as ventilation or other dust suppression methods and enclosed 
workstations such as control booths and equipment cabs; requirements 
for maintenance and evaluation of engineering controls; and 
implementation of certain work practices such as not working in areas 
where visible dust is generated from respirable crystalline silica 
containing materials without use of respiratory protection. For 
employers in general industry and maritime, as well as those in 
construction following paragraph (d) for tasks not listed in Table 1 or 
where the employer does not fully and properly implement the 
engineering controls, work practices, and respiratory protection 
described in Table 1, OSHA similarly requires the use of engineering 
and work practices controls to reduce employee exposures to or below 
the PEL; however, this is a performance requirement and does not 
specify any particular engineering and work practice controls that must 
be implemented.
    Paragraph (f)(2)(i) of the standard for general industry and 
maritime (paragraph (g)(1) of the standard for construction) requires 
that employers establish and implement a written exposure control plan. 
Paragraphs (f)(2)(i)(A)-(C) (paragraphs (g)(1)(i)-(iv) of the standard 
for construction) specify the contents for written exposure control 
plans. Paragraph (f)(2)(ii) (paragraph (g)(2) of the standard for 
construction) specifies requirements for the employer to review the 
plan at least annually and update it as needed. Paragraph (f)(2)(iii) 
(paragraph (g)(3) of the standard for construction) requires the 
employer to make the plan available to employees, employee 
representatives, OSHA, and NIOSH. Details about the written exposure 
control plan, including comments from stakeholders and OSHA's responses 
to those comments, are included in the summary and explanation of 
Written Exposure Control Plan.
    SECALs. In the NPRM, OSHA asked stakeholders to provide input as to 
whether the Agency should establish separate engineering control air 
limits (SECALs) for certain processes in selected industries. In OSHA's 
cadmium standard (29 CFR 1910.1027 (f)(1)(ii), (iii), and (iv)), the 
Agency established SECALs where compliance with the PEL by means of 
engineering and work practice controls was infeasible. For these 
industries, a SECAL was established at the lowest feasible level that 
could be achieved by engineering and work practice controls. The PEL 
was set at a lower level, and could be achieved by any allowable 
combination of controls, including respiratory protection. A similar 
exception was included in OSHA's chromium (VI) standard (29 CFR 
1910.1026) for painting aircraft and large aircraft parts.
    OSHA received feedback from several commenters who supported 
establishing SECALs (e.g., Document ID 2082, p. 8; 2379, Appendix 1, p. 
61; 2380, Attachment 2, p. 23). For example, AFS argued for a SECAL of 
150 or 200 [mu]g/m\3\ for foundries, with a PEL of 100 [mu]g/m\3\. AFS 
indicated that many foundries now operate under a formal or informal 
arrangement with OSHA that allows use of respirators as an acceptable 
control to achieve compliance with the current PEL after implementing 
all feasible engineering controls (Document ID 2379, Appendix 1, p. 
61). ORCHSE Strategies stated that the use of SECALs could provide more 
definitive expectations for employers based on the feasibility for 
engineering controls in specific operations (Document ID 2277, p. 2). 
The United Automobile, Aerospace and Agricultural Implement Workers of 
America recommended that the PEL be even lower than OSHA proposed (25 
[mu]g/m\3\), and suggested that SECALs could be established for those 
industries for which 25 [mu]g/m\3\ is not feasible (Document ID 2282, 
p. 16).
    Other commenters did not favor establishing SECALs. CISC stated 
that it did not support the concept of SECALs, but that CISC would 
continue to examine whether a SECAL was appropriate for the 
construction industry (Document ID 2319, p. 128). NIOSH did not support 
the use of SECALs and stated that the requirement to meet the PEL for 
silica generating processes should be maintained (Document ID 2177, 
Attachment B, p. 16).
    OSHA stresses that, where incorporated in a standard, a SECAL is 
intended for application to discrete processes and operations within an 
industry, rather than application to an entire industry, as some 
supporters of SECALs seemed to suggest. For example, in OSHA's cadmium 
standard, OSHA established SECALs for certain plating and other 
processes in a few affected industries. OSHA did not receive evidence 
to support establishing a SECAL for any discrete task or operation 
within a particular industry in the respirable crystalline silica rule. 
OSHA therefore has not established SECALs in the rule.
    Abrasive blasting. Abrasive blasting requirements remain the same 
as proposed, except for minor editorial changes. Paragraph (f)(3) of 
the standard for general industry and maritime (paragraph (d)(3)(ii) of 
the standard for construction) requires the employer to comply with 
paragraph (f)(1) of the standard for general industry and maritime 
(paragraph (d)(3)(i) of the standard for construction) where abrasive 
blasting is conducted using crystalline silica-containing blasting 
agents, or where abrasive blasting is conducted on substrates that 
contain crystalline silica. Thus, for abrasive blasting, employers must 
follow the hierarchy of controls applicable to other tasks covered by 
the rule.
    In this provision addressing abrasive blasting, the proposed 
standard referred to ``where abrasive operations are conducted,'' but 
for simplicity, this standard refers to ``where abrasive blasting is 
conducted.'' OSHA intends this change to be editorial only, and does 
not intend a substantive change from the proposed requirements.
    In addition, paragraph (f)(3) of the standard for general industry 
and maritime indicates that the employer must comply with the 
requirements of 29 CFR 1910.94 (Ventilation), 29 CFR 1915.34 
(Mechanical paint removers) and 29 CFR 1915 Subpart I, as applicable, 
where abrasive blasting is conducted using crystalline silica-
containing blasting agents, or where abrasive blasting is conducted on 
substrates that contain crystalline silica. Paragraph (d)(3)(ii) of the 
standard for construction indicates that the employer must comply with 
the requirements of 29 CFR 1926.57 (Ventilation) in such circumstances.

[[Page 16787]]

    OSHA's general industry (29 CFR 1910.94) and construction 
ventilation standards (29 CFR 1926.57), as well as the standards for 
mechanical paint removers (29 CFR 1915.34) and personal protective 
equipment for shipyard employment (29 CFR 1915 subpart I) provide 
requirements for respiratory protection for abrasive blasting operators 
and others involved in abrasive blasting. This rule includes cross-
references to these standards. Employers using abrasive blasting need 
to consult these referenced standards to ensure that they comply with 
their provisions for personal protective equipment and ventilation, and 
other operation-specific safety requirements.
    ISEA urged OSHA to add a reference to the APF table at 29 CFR 
1910.134(d)(3)(i)(A) in the general industry and construction standards 
for ventilation, and to require that if the employer has no sampling 
data to support the use of an abrasive blasting respirator with an APF 
of 25, the employer must select a respirator with an APF of 1,000 
(Document ID 2212, p. 1). The 3M Company similarly questioned the 
respirator requirements under the ventilation standards, arguing that 
without considering the performance (APF) of the respirator, some 
employees could be overexposed to silica (Document ID 2313, pp. 1, 5-
6). Charles Gordon, a retired occupational safety and health attorney, 
commented that even with the reference to the ventilation standards, 
the provision is not protective enough. He encouraged the Agency to 
require the most protective abrasive blasting hood and respirators and 
require the best work practices (Document ID 2163, Attachment 1, p. 
19).
    Given the high levels of hazardous dust generated during abrasive 
blasting, OSHA has concluded, for reasons discussed in its 
technological feasibility analyses for construction and for certain 
general industry sectors like foundries and shipyards that perform 
abrasive blasting in their operations, that respiratory protection will 
continue to be necessary to reduce silica exposure below the PEL, even 
with engineering and work practice controls in place (see the 
discussion of abrasive blasting in Chapter IV of the FEA). This 
standard also takes respirator use into account by cross-referencing 
the specific respirator requirements already in place for abrasive 
blasting. Employers are also required to comply with the requirements 
of 29 CFR 1910.134 whenever respiratory protection is required by this 
section. Under 29 CFR 1910.134, the employer is required to select and 
provide an appropriate respirator based on the respiratory hazards to 
which the employee is exposed and is required to use the APF table at 
29 CFR 1910.134(d)(3)(i)(A). This includes note four of the APF table, 
which requires the employer to have evidence to support an APF of 1000 
for helmet/hood respirators. In addition, paragraph (d) of the standard 
for general industry and maritime and paragraph (d)(2) of the standard 
for construction require employers to assess the exposure of each 
employee who is or may reasonably be expected to be exposed to 
respirable crystalline silica at or above the action level, which will 
provide employers with information to make appropriate respirator 
selection decisions. OSHA concludes that these requirements, including 
the referenced provisions in other OSHA standards, will adequately 
protect employees from exposures to respirable crystalline silica 
during abrasive blasting.
    Many commenters, including NIOSH, labor unions, public health 
organizations, trade associations, occupational health medical 
professionals, and public interest organizations, urged OSHA to ban the 
use of silica sand as an abrasive blasting agent (Document ID 2167; 
2173, p. 4; 2175, pp. 7-8; 2177, Attachment B, p. 37; 2178, Attachment 
1, p. 3; 2212, p. 1; 2240, p. 2; 2244, p. 2; 2256, Attachment 2, pp. 
12-13; 2282, Attachment 3, pp. 2, 18; 2341, p. 3; 2371, Attachment 1, 
p. 31; 2373, p. 3; 3399, p. 6; 3403, p. 7; 3577, Tr. 779-780, 785, 790; 
3586, Tr. 3319-3320, 3163; 3588, Tr. 3752; 4204, p. 81; 4223, pp. 104-
106). Some noted that 4 countries (Great Britain, Germany, Sweden, and 
Belgium), several U.S. military departments, and 23 state Departments 
of Transportation have already banned the practice (Document ID 2167; 
2175, pp. 7-8; 2178, Attachment 1, p. 3; 2256, Attachment 2, pp. 12-13; 
2212, p. 1; 2282, Attachment 3, p. 18; 2371, Attachment 1, p. 31; 2373, 
p. 3; 3399, p. 6; 4204, p. 76).
    Fann Contracting, Dr. Kenneth Rosenman, an expert in occupational 
and environmental disease, and Novetas Solutions noted the broad trend 
of abrasive blasting operations moving away from sand (Document ID 
2116, Attachment 1, pp. 31-32; 3577, Tr. 858; 3588, Tr. 3992-3993). The 
American Federation of State, County and Municipal Employees reported 
that several local Maryland unions no longer use silica-based blasting 
agents and have substituted other materials, such as aluminum shot 
(Document ID 2106, p. 2). Sarah Coyne, a former painter and current 
Health and Safety Director for IUPAT, discussed how their signatory 
contractors have largely transitioned from silica sand to coal slag for 
abrasive blasting (Document ID 3581, Tr. 1644). API noted that many oil 
and gas companies have limited or eliminated respirable crystalline 
silica exposure in sandblasting operations by using media options that 
do not contain silica (Document ID 2301, Attachment 1, p. 5). NADA also 
noted that product substitution has minimized potential exposures to 
airborne crystalline silica-containing media (Document ID 2358, p. 4). 
The Interstate Natural Gas Association of America stated that members 
utilize other abrasives to the extent feasible, including fused glass 
in limited applications (Document ID 2081, p. 2).
    As OSHA indicated in its NPRM, the use of silica sand for abrasive 
blasting operations is decreasing (Document ID 1420). This reduction 
might reflect the use of alternative blasting media, the increased use 
of high-pressure water-jetting techniques, and the use of cleaning 
techniques that do not require open sand blasting. Several substitutes 
for silica sand are available for abrasive blasting operations, and 
current data indicate that the abrasive products with the highest U.S. 
consumptions are: Coal slag, copper slag, nickel slag, garnet, 
staurolite, olivine, steel grit, and crushed glass. Several commenters 
(Adam Webster, Charles Gordon, and the Association of Occupational and 
Environmental Clinics) also noted the general availability of 
alternative abrasive blast media, including baking soda, water, dry 
ice, coal/copper slag, glass beads, walnut shells, and carbon dioxide 
(Document ID 2163, p. 19; 2167; 3399, p. 6). Additional alternatives 
are discussed and evaluated in Chapter IV of the FEA. On the other 
hand, PCI commented that the use of alternative abrasive blast media 
was precluded in the precast concrete structures industry, since many 
alternatives will not meet aesthetic requirements, are not aggressive 
enough to provide the desired finished, or are simply cost prohibitive 
(Document ID 2276, p. 9). Furthermore, CISC warned about possible 
hazards associated with the substitutes for silica sand (Document ID 
2319, p. 37). PCI and Novetas Solutions cautioned that coal and copper 
slags, commonly used as a substitute for silica sand in abrasive 
blasting, contain hazardous substances such as beryllium that cause 
adverse health effects in employees (Document ID 2276, p. 9; 3588, Tr. 
3992-4004). Meeker et al. (2006) found elevated levels of exposure to 
arsenic, beryllium, and other toxic metals among painters using three

[[Page 16788]]

alternative blasting abrasives (Document ID 3855).
    A NIOSH study compared the short-term pulmonary toxicity of several 
abrasive blasting agents (Document ID 1422). This study reported that 
specular hematite and steel grit presented less short-term in vivo 
toxicity and respirable dust exposure in comparison to blast sand. 
Overall, crushed glass, nickel glass, staurolite, garnet, and copper 
slag were similar to blast sand in both categories. Coal slag and 
olivine showed more short-term in vivo toxicity than blast sand and 
were reported as similar to blast sand regarding respirable dust 
exposure. This study did not examine long-term hazards or non-pulmonary 
effects.
    Additionally, another NIOSH study monitored exposures to several 
OSHA-regulated toxic substances that were created by the use of silica 
sand and substitute abrasive blasting materials (Document ID 0772). The 
study showed that several substitutes create exposures or potential 
exposures to various OSHA-regulated substances, including: (1) Arsenic, 
when using steel grit, nickel slag, copper slag and coal slag; (2) 
beryllium, when using garnet, copper slag, and coal slag; (3) cadmium, 
when using nickel slag and copper slag; (4) chromium, when using steel 
grit, nickel slag, and copper slag; and (5) lead, when using copper 
slag. Since these studies were performed, OSHA has learned that 
specular hematite is not being manufactured in the United States due to 
patent-owner specification. In addition, the elevated cost of steel has 
a substantial impact on the availability to some employers of 
substitutes like steel grit and steel shot.
    Evidence in the rulemaking record indicates that elevated silica 
exposures have been found during the use of low-silica abrasives as 
well, even when blasting on non-silica substrates. For example, the use 
of the blasting media Starblast XL (staurolite), which contains less 
than one percent quartz according to its manufacturer, resulted in a 
respirable quartz level of 1,580 [mu]g/m\3\. The area sample (369-
minute) was taken inside a containment structure erected around two 
steel tanks. The elevated exposure occurred because the high levels of 
abrasive generated during blasting in containment overwhelmed the 
ventilation system (Document ID 0212). This example emphasizes the 
impact of control methods in specific working environments. In order to 
reduce elevated exposures to or as close as feasible to the PEL in 
situations like these, employers need to examine the full spectrum of 
available controls and how these controls perform in specific working 
conditions.
    After considering the arguments for and against prohibition, OSHA 
concludes that prohibiting the use of silica sand as an abrasive 
blasting agent is not appropriate. In so concluding, the Agency 
considered whether such a prohibition is an effective risk mitigation 
measure, as well as the technological feasibility of substitutes. The 
Agency finds that many of the silica sand substitutes used in abrasive 
blasting can create hazardous levels of toxic dust other than silica, 
as documented in studies conducted by NIOSH on the toxicity of silica 
sand substitutes for abrasive blasting; NIOSH found that many, 
including coal slag, garnet, copper and nickel slags, olivine, and 
crushed glass, produced lung damage and inflammatory reactions in 
rodent lung similar to that of silica sand, indicating that use of such 
materials would present lung disease risks to employees (Document ID 
3857; 3859). OSHA further finds that additional toxicity data are 
necessary before the Agency can reach any conclusions about the hazards 
of these substitutes relative to the hazards of silica. Given the 
concerns about potential harmful exposures to other substances that the 
alternatives might introduce in a workplace, as well as the potential 
for continued exposure to respirable crystalline silica, OSHA concludes 
that banning the use of silica sand as an abrasive blasting agent would 
not necessarily effectively mitigate risk. OSHA also concludes, as 
detailed in the FEA, that the general prohibition of silica sand in 
abrasive blasting is not technologically or economically feasible. 
Thus, the Agency has decided against a ban or limitation on the use of 
silica sand as an abrasive blasting agent in the rule.
    BCTD urged OSHA to ban the use of silica sand as an abrasive 
blasting agent, but said that if banning the use of silica sand as an 
abrasive blasting agent was not possible, OSHA should prohibit the use 
of dry silica sand as an abrasive blasting agent (Document ID 2371, 
Attachment 1, p. 31). However, PCI noted that wet blasting with silica 
sand cannot be used to finish concrete surfaces (Document ID 2276, p. 
9). CISC noted the problems associated with excessive water application 
on some worksites and argued that different environments and conditions 
had not been analyzed to determine the effectiveness of wet methods for 
abrasive blasting (Document ID 2319, p. 36).
    OSHA finds that a separate requirement for the use of wet blasting 
methods when silica sand is used as a blasting agent is neither 
necessary nor appropriate. Under paragraph (f)(1) of the standard for 
general industry and maritime (paragraph (d)(3)(i) of the standard for 
construction), employers are required to use engineering and work 
practice controls, which include wet methods, to reduce and maintain 
employee exposure to respirable crystalline silica at or below the PEL, 
unless the employer can demonstrate that such controls are not 
feasible. Therefore, where employee exposures exceed the PEL from 
abrasive blasting with silica sand, employers must implement wet 
blasting methods whenever such methods are feasible and would reduce 
exposures, even if implementing this control does not reduce exposures 
to or below the PEL. By not specifically mandating the use of wet 
methods whenever sand is used as a blasting agent, the rule gives 
employers who cannot feasibly use wet methods flexibility to determine 
what controls to implement in order with comply with the PEL.
    Charles Gordon argued for a partial ban on the use of silica sand 
as an abrasive blasting agent:

    Abrasive blasting with crystalline silica should be banned in 
confined spaces and in the maritime industry. That is where acute 
silicosis was most common and where it is hardest to protect 
adjacent workers.
    In all other areas and operations, the employer must consult 
MSDS's for substitutes for crystalline silica. If it is reasonable 
to conclude that a substitute for crystalline silica is a safer 
blasting media and will lead to a reasonable surface, then the 
employer must adopt the substitute. If the employer concludes that 
there is no safer reasonable substitute for crystalline silica, then 
the employer must keep a brief written record of that determination 
(Document ID 2163, Attachment 1, pp. 18-19).

While OSHA has declined to ban abrasive blasting with crystalline 
silica in any setting, the Agency considers that the process of 
selecting, evaluating, and adopting safer blasting agent substitutes 
where feasible, is consistent with the analysis required under 
paragraph (f)(1) of the standard for general industry and maritime 
(paragraph (d)(3)(i) of the standard for construction). As part of 
complying with this paragraph, employers must consider whether 
substitutes for crystalline silica abrasive blasting agents are 
available. Safer, effective, and feasible substitutes, where available, 
should be included as part of the package of feasible engineering and 
work practice controls required to reduce employee exposure to 
respirable crystalline silica to or below the PEL. The Agency expects 
that the requirements in the rule will incentivize

[[Page 16789]]

employer evaluation and adoption of substitute materials where 
substitution is appropriate for the task and shown to be safe, while 
avoiding substitutions that pose comparable or greater risk and 
maintaining flexibility for employers to determine what controls to 
implement in order to comply with the PEL.
    CISC questioned the application of the hierarchy of controls to 
abrasive blasting, given the Agency's acknowledgement that respiratory 
protection will still be necessary in many situations even after 
implementing engineering and work practice controls (Document ID 2319, 
p. 37). As discussed above, the Agency maintains its position that 
adherence to the hierarchy of controls, which includes, where 
appropriate and feasible, substitutes for silica sand, wet blasting, 
LEV, proper work practices and housekeeping practices that reduce dust 
emissions, is essential to help reduce the extremely high exposures to 
respirable crystalline silica experienced by abrasive blasting workers 
and workers who may be near them. The FEA describes how extremely high 
exposures associated with dry abrasive blasting were significantly 
reduced where controls, such as wet blasting and non-silica containing 
abrasive blast media, were used (see Chapter IV of the FEA for further 
discussion). By using engineering controls to reduce these exposures, 
employees will be able to wear less restrictive respirators and will be 
better protected if their respiratory protection fails. Engineering 
controls also help protect others on the worksite from exposure to 
respirable crystalline silica. Therefore, requiring the use of 
controls, even where respiratory protection will also be required, is 
reasonably necessary and appropriate to protect employees from 
exposures to respirable crystalline silica.
    The requirements in the rule for abrasive blasting are consistent 
with ASTM E 1132--06 and ASTM E 2625--09, the national consensus 
standards for controlling occupational exposure to respirable 
crystalline silica in general industry and in construction, 
respectively. Each of these standards clarifies that the hierarchy of 
controls (i.e., using alternative materials, wet suppression systems, 
or exhaust ventilation, where feasible, to reduce exposures) applies to 
abrasive blasting and refers to the existing requirements under OSHA's 
ventilation standards (29 CFR 1910.94 and 29 CFR 1926.57).
    Employee rotation. OSHA proposed, but is not including in the final 
rule, a provision specifying that the employer must not rotate 
employees to different jobs to achieve compliance with the PEL. The 
Agency proposed this prohibition because silica is a carcinogen, and 
OSHA considers that any level of exposure to a carcinogen places an 
employee at risk. With employee rotation, the population of exposed 
employees increases. A prohibition on rotation has been included in 
other OSHA health standards that address carcinogens, such as the 
standards for asbestos (29 CFR 1910.1001), chromium (VI) (29 CR 
1910.1026), 1,3-butadiene (29 CFR 1910.1051), methylene chloride (29 
CFR 1910.1052), cadmium (29 CFR 1910.1027), and methylenedianiline (29 
CFR 1910.1050). However, other standards addressing chemicals that were 
associated with non-cancer health effects, such as the standards for 
lead and cotton dust (29 CFR 1910.1025 and 29 CFR 1910.1043), do not 
include a prohibition on employee rotation to achieve the PEL. In 
response to a recommendation by the Small Business Advocacy Review 
Panel, OSHA solicited comment in the NPRM on the prohibition of 
employee rotation to achieve compliance with the PEL (78 FR 56273, 
56290 (9/12/13)).
    A prohibition on employee rotation to achieve compliance with the 
PEL was supported by EEI, Dr. George Gruetzmacher, and James Schultz 
(Document ID 2278, p. 4; 2357, p. 30; 3586, Tr. 3200). However, many 
commenters representing employers from the concrete, brick, tile, 
construction, electric utility, and foundry industries, over 20 trade 
associations, ASSE, and academics from the George Washington University 
Regulatory Studies Center urged OSHA to reconsider this prohibition 
(e.g., Document ID 1785, p. 8; 1831, p. 15; 1992, p. 11; 2023, p. 7; 
2024, p. 3; 2075, p. 3; 2102, p. 2; 2116, Attachment 1, pp. 34-35; 
2119, Attachment 3, p. 7; 2145, pp. 5-6; 2147, p. 4; 2150, p. 2; 2154, 
Attachment 3, p. 7; 2185, pp. 6-7; 2195, p. 39; 2213, p. 4; 2215, p. 
11; 2222, p. 2; 2241, p. 2; 2245, p. 3; 2255, p. 3; 2276, p. 10; 2279, 
p. 10; 2288, p. 12; 2296, p. 42; 2305, pp. 11, 15; 2309, p. 3; 2322, p. 
14; 2326, p. 3; 2339, p. 4; 2348, Attachment 1, p. 36; 2355, p. 2; 
2359, Attachment 1, p. 11; 2370, p. 2; 2379, Appendix 1, p. 69; 2380, 
Attachment 2, p. 21; 2384, p. 10; 2391, p. 2; 3245, p. 2; 3275, p. 2; 
3489, p. 4; 3491, p. 4; 3578, Tr. 1035-1036, 1044; 3729, p. 3; 4194, p. 
12; 4213, p. 7; 4226, p. 2).
    Some commenters misunderstood the prohibition on employee rotation 
to achieve compliance with the PEL, or believed that the provision 
could be misunderstood by the regulated community. These commenters 
were concerned that the prohibition would preclude the use of rotation 
for other reasons, such as limiting exposure to physical hazards (e.g., 
noise, vibration, repetitive motion stresses), providing cross-
training, improving productivity, preventing fatigue, and filling in 
for other employees. OSHA explained in the NPRM that the proposed 
provision was not intended as a general prohibition on employee 
rotation. However, commenters including National Electrical Carbon 
Products, OSCO, the Ohio Cast Metals Association, PCI, and AFS 
expressed concerns that using employee rotation for these other reasons 
could be misinterpreted as a violation of the prohibition (e.g., 
Document ID 1785, p. 8; 1992, p. 11; 2119, Attachment 3, p. 7; 2276, p. 
10; 3489, p. 4;). NISA also asked the Agency to clarify that rotation 
may be performed for purposes other than achieving compliance with the 
PEL (Document ID 2195, p. 39).
    NISA and the Chamber argued that if the risks of silicosis are 
subject to a threshold, then rotation to maintain exposures at low 
levels could only be protective (Document ID 2195, p. 39; 2288, p. 12; 
4194, p. 12). ASSE argued that job rotation may be warranted as an 
alternative to burdensome engineering and administrative controls or 
PPE for tasks that involve some levels of exposure to silica, but are 
performed on an infrequent basis (Document ID 2339, p. 4; 3578, Tr. 
1035-1036, 1044). ASSE, as well as Dal-Tile, noted that since silica is 
a ubiquitous substance and present in many raw materials, virtually all 
employees would be exposed to some level of respirable crystalline 
silica. Therefore, they argued that a prohibition on rotation in this 
circumstance does not make sense (Document ID 2147, p. 4; 2339, p. 4). 
In addition, AFS indicated that rotation as an administrative control 
is permitted by Canadian provinces with exposure limits for respirable 
crystalline silica (Document ID 4035, p. 14). OSHA also notes that the 
industry consensus standards for respirable crystalline silica, ASTM E 
1132-06 and ASTM E 2625-09, expressly permit employee rotation as an 
administrative control to limit exposures (Document ID 1466, p. 4; 
1504, pp. 3, 7).
    OSHA does not consider employee rotation to be an acceptable 
alternative to avoid the costs associated with implementation of 
engineering and administrative controls, nor does the Agency consider 
that pervasive exposures to respirable crystalline silica justify 
allowing rotation. OSHA has nonetheless concluded that there may be 
situations where employee rotation

[[Page 16790]]

may be an acceptable measure to limit the need for respiratory 
protection. For example, OSHA has determined that the majority of 
employers covered by the rule will be in construction, and expects that 
most construction employers will implement the controls listed on Table 
1 in paragraph (c) of the standard for construction. A number of tasks 
listed on Table 1 require respiratory protection, in addition to 
engineering and work practice controls, when performed for more than 
four hours per shift. Where the employer has implemented the 
engineering and work practice controls specified in Table 1, OSHA 
accepts the rationale that it may be reasonable to rotate employees to 
avoid exceeding the four-hour threshold that would trigger a 
requirement for respirator use. As discussed earlier in this section, 
respirator use can restrict visibility, impair communication, 
contribute to heat stress, strain the respiratory and cardiac systems, 
and exacerbate other safety and health hazards, such as trip and fall 
hazards. Under such circumstances, rotation of employees to limit use 
of respiratory protection may serve to reduce overall risks to 
employees. Rotation may also allow employees to continue to work if 
they are unable to pass the medical evaluation for respirator use, but 
are otherwise capable of performing the work.
    OSHA also recognizes that a provision prohibiting employee rotation 
to achieve the PEL has little practical application for purposes of 
enforcement. Because the prohibition is limited to rotation for the 
sole purpose of achieving the PEL, an employer can provide any other 
reason to justify employee rotation. As described above, there are many 
legitimate reasons for an employer to rotate employees. As a result, 
OSHA has almost never cited employers for violating provisions 
prohibiting employee rotation for achieving the PEL. For the 7 
standards that contain these provisions, which have been in effect for 
periods ranging from 8 to 29 years, Federal OSHA has only cited one of 
these provisions on one occasion.
    For the reasons described above, OSHA has determined that a 
prohibition on employee rotation to achieve the PEL is not reasonably 
necessary or appropriate for the silica rule. The Agency recognizes 
that this determination differs from the determinations made in 
previous rulemakings addressing carcinogens. This is not intended as a 
reversal of OSHA's prior practice of prohibiting employee rotation to 
achieve the PEL for carcinogens, nor a precedent that will control 
future rulemakings, which necessarily will be based on different 
rulemaking records. Nevertheless, in this rule OSHA expects that the 
majority of employers covered by the rule will implement all feasible 
engineering and work practice controls to achieve the PEL (as the rule 
requires), and rotation will generally be used to limit use of 
respiratory protection that is triggered by working more than four 
hours in conditions where exposures are expected above the PEL even 
with the full implementation of engineering and work practice controls. 
OSHA finds that these factors justify omitting the prohibition on 
rotation from this rule. Therefore, the prohibition, which was included 
in the proposed rule, is not included in the final rule.

Respiratory Protection

    Paragraph (g) of the standard for general industry and maritime 
(paragraph (e) of the standard for construction) establishes 
requirements for the use of respiratory protection, to which OSHA's 
respiratory protection standard (29 CFR 1910.134) also applies. 
Specifically, respirators are required under the rule: Where exposures 
exceed the PEL during periods necessary to install or implement 
engineering and work practice controls; where exposures exceed the PEL 
during tasks, such as certain maintenance and repair tasks, for which 
engineering and work practice controls are not feasible; and during 
tasks for which all feasible engineering and work practice controls 
have been implemented but are not sufficient to reduce exposure to or 
below the PEL. The standard for general industry and maritime also 
requires respiratory protection during periods when an employee is in a 
regulated area. The standard for construction also requires respiratory 
protection where specified by Table 1 of paragraph (c), but does not 
include a requirement to establish a regulated area, and thus does not 
contain a provision requiring the use of respirators in regulated 
areas.
    These provisions of the rule for the required use of respirators 
are consistent with those proposed and are generally consistent with 
other OSHA health standards, such as methylene chloride (29 CFR 
1910.1052) and chromium (VI) (29 CFR 1910.1026). They reflect the 
Agency's determination that, as discussed in the summary and 
explanation of Methods of Compliance, respirators are inherently less 
reliable than engineering and work practice controls in reducing 
employee exposure to respirable crystalline silica. OSHA therefore is 
allowing reliance on respirators to protect against exposure to 
respirable crystalline silica only in specific circumstances where 
engineering and work practice controls are in the process of being 
installed or implemented (and thus are not yet fully operational), are 
not feasible, or cannot by themselves reduce exposures to the PEL. In 
those circumstances, OSHA's hierarchy of controls contemplates 
requiring the use of respirators as a necessary supplement to 
engineering, work practice, and administrative controls.
    Paragraph (e)(1) of the standard for construction is revised from 
the proposed standard in order to clarify where respiratory protection 
is required. Paragraph (e)(1)(i) of the standard for construction 
provides that, for employers following the specified exposure control 
methods approach set forth in paragraph (c) of the standard for 
construction, respiratory protection is required under the standard 
where specified by Table 1. Table 1 in paragraph (c) of the standard 
for construction specifies respirator use for certain listed tasks; 
employers whose employees are engaged in those tasks have the option of 
following Table 1 in order to comply with the standard. The specific 
respiratory protection and minimum assigned protection factors (APF) 
for the tasks listed on Table 1 are discussed in the summary and 
explanation of Specified Exposure Control Methods. Paragraph (e)(1)(ii) 
of the standard for construction establishes where respirators are 
required for employees who are not performing tasks listed on Table 1 
or where the engineering controls, work practices, and respiratory 
protection described in Table 1 are not fully and properly implemented 
(including where the employer chooses to follow paragraph (d) rather 
than follow paragraph (c)). Specifically, respirators are required in 
each of the situations described in paragraphs (e)(1)(ii)(A)-(C).
    Paragraph (g)(1)(i) of the standard for general industry and 
maritime (paragraph (e)(1)(ii)(A) of the standard for construction) 
requires the use of respirators in areas where exposures exceed the PEL 
during periods when feasible engineering and work practice controls are 
being installed or implemented. OSHA recognizes that respirators may be 
needed to achieve the PEL under these circumstances. During these 
times, employees will have to use respirators for temporary protection 
until the hierarchy of controls has been implemented, at which point 
respirators will not be needed, provided the PEL is no longer exceeded. 
Employers must follow the

[[Page 16791]]

requirements for exposure assessment (see the summary and explanation 
of Exposure Assessment) to determine the extent of employee exposures 
once engineering and work practice controls are installed or 
implemented. While there is not an established time for exposure 
assessments to occur after the installation or implementation of 
controls, employers are required to reassess exposures whenever a 
change in control equipment may reasonably be expected to result in new 
or additional exposures above the action level. Employers must also 
ensure that employee exposures are accurately characterized, so they 
would need to reassess exposures after the installation or 
implementation of controls in order to meet this obligation.
    OSHA anticipates that engineering controls will be in place by the 
dates specified in paragraphs (l)(2) and (l)(3) of the general industry 
and maritime standard (paragraph (k)(2) of the standard for 
construction) (see the summary and explanation of Dates for discussion 
of these requirements). However, the Agency realizes that in some cases 
employers may commence operations, install new or modified equipment, 
or make other workplace changes that result in new or additional 
exposures to respirable crystalline silica after the dates specified. 
In these cases, a reasonable amount of time may be needed before 
appropriate engineering controls can be installed and proper work 
practices implemented. When employee exposures exceed the PEL in these 
situations (see the summary and explanation of Exposure Assessment for 
an explanation of the requirements to assess employee exposure to 
respirable crystalline silica), employers must provide their employees 
with respiratory protection and ensure its use.
    Paragraph (g)(1)(ii) of the general industry and maritime standard 
(paragraph (e)(1)(ii)(B) of the standard for construction) requires 
respiratory protection in areas where exposures exceed the PEL during 
tasks in which engineering and work practice controls are not feasible. 
OSHA anticipates that there will be few situations where no feasible 
engineering or work practice controls are available to limit employee 
exposure to respirable crystalline silica. However, the Agency 
recognizes that it may be infeasible to control respirable crystalline 
silica exposure with engineering and work practice controls during 
certain tasks, such as maintenance and repair tasks, and permits the 
use of respirators in these situations. For example, maintenance and 
repair to address temporary failures in operating systems or control 
systems to achieve the PEL such as failures of conveyance systems 
(elevators, conveyors, or pipes), failures of dust collecting bag 
systems, and section head failures at glass plant facilities as well as 
cupola (furnace) repair work and baghouse maintenance activities, may 
present a situation where engineering and work practice controls are 
not feasible and the use of respirators is permitted (Document ID 3493, 
p. 3; 1992, pp. 3, 5). In situations where respirators are used as the 
only means of protection, the employer must be prepared to demonstrate 
that engineering and work practice controls are not feasible.
    Paragraph (g)(1)(iii) of the standard for general industry and 
maritime (paragraph (e)(1)(ii)(C) of the standard for construction) 
requires the use of respirators for supplemental protection in 
circumstances where feasible engineering and work practice controls 
alone are not sufficient to reduce exposure levels to or below the PEL. 
The employer is required to install and implement all feasible 
engineering and work practice controls, even if these controls alone 
cannot reduce employee exposures to or below the PEL. Whenever 
respirators are used as supplemental protection, the burden is on the 
employer to demonstrate that engineering and work practice controls 
alone are insufficient to achieve the PEL.
    Paragraph (g)(1)(iv) of the standard for general industry and 
maritime requires employers to provide respiratory protection during 
periods when an employee is in a regulated area. Paragraph (e) of the 
standard for general industry and maritime requires employers to 
establish a regulated area wherever an unprotected employee's exposure 
to airborne concentrations of respirable crystalline silica is, or can 
reasonably be expected to be, in excess of the PEL. OSHA included the 
provision requiring respirator use in regulated areas to make it clear 
that each employee is required to wear a respirator when present in a 
regulated area, regardless of the duration of time spent in the area. 
Because of the potentially serious results of exposure, OSHA has 
concluded that this provision is necessary and appropriate because it 
would limit unnecessary exposures to employees who enter regulated 
areas, even if they are only in a regulated area for a short period of 
time. The standard for construction does not include a requirement to 
establish a regulated area and thus, does not contain a similar 
provision in the respiratory protection section of the standard. 
Further discussion about this can be found in the summary and 
explanation of Regulated Areas and Written Exposure Control Plan.
    OSHA proposed to require the use of respiratory protection when 
specified by the written access control plan--an option given to 
employers in the proposed rule as an alternative to establishing 
regulated areas. The Agency is not including an access control plan 
option in the rule (see discussion in the summary and explanation of 
Regulated Areas). Thus, without an option for an employer to develop a 
written access control plan, there is no reason to require respirators 
pursuant to a written access control plan.
    Commenters, including Charles Gordon, a retired occupational safety 
and health attorney, and the American Industrial Hygiene Association 
recommended that OSHA require employers to provide employees with 
respirators upon request in certain situations where they are not 
required under the rule (e.g., exposures below the PEL, Table 1 tasks 
for which respirators are not required) (Document ID 2163, Attachment 
1, p. 16; 2169, p. 5). Dr. George Gruetzmacher, an industrial hygiene 
engineer, suggested that OSHA require respiratory protection and a 
respiratory protection program at the action level (Document ID 2278, 
p. 4).
    While the Agency considers the level of risk remaining at the PEL 
to be significant, OSHA is not including a provision in this rule 
permitting employees to request and receive a respirator in situations 
where they are not required under the rule, nor is OSHA requiring 
respiratory protection and a respiratory protection program at the 
action level. There has been significant residual risk below the PEL in 
many previous health standards, but OSHA has only rarely included 
provisions permitting employees to request and receive a respirator to 
mitigate this risk (cotton dust (29 CFR 1910.1043(f)(1)(v)), lead (29 
CFR 1910.1025(f)(1)(iii)), cadmium (29 CFR 1910.1027(g)(1)(v))) and the 
Agency has never established a requirement for respiratory protection 
and a respiratory protection program at a standard's action level.
    OSHA anticipates that most construction employers covered by the 
rule will choose to implement the control measures specified in 
paragraph (c) of the standard for construction. Employers who implement 
the specified exposure control methods will not be required to assess 
employee exposures to respirable crystalline silica. Therefore, many 
employers covered by

[[Page 16792]]

the rule will not be aware if their employees are exposed to respirable 
crystalline silica at or above the action level. In order to impose a 
requirement for employers to provide respirators to employees exposed 
at or above the action level, OSHA would first need to require 
employers to assess the exposures of all employees in order to 
determine which employees are exposed at or above the action level. As 
discussed in the summary and explanation of Specified Exposure Control 
Methods, OSHA has concluded that such an exposure assessment 
requirement is not necessary for employers who implement the controls 
listed on Table 1.
    With regard to permitting employees to request respirators for 
Table 1 tasks where respiratory protection is not specified, OSHA has 
relied on its technological feasibility analyses to determine which 
tasks can be performed at or below the PEL most of the time with the 
use of engineering and work practice controls only (i.e., without 
respirators), and has concluded that employers who implement the 
controls listed on Table 1 for these tasks will provide equivalent 
overall protection for their employees as employers who perform 
exposure assessment and follow the alternative exposure control methods 
option provided in paragraph (d). If an employer follows Table 1 and 
Table 1 does not require use of a respirator, the employee's exposure 
will generally be below the PEL. There may be exceptions, but this is 
no different than when monitoring is conducted--monitoring two or four 
times a year does not perfectly characterize exposures, and there will 
be situations where exposures exceed the PEL even when good faith 
monitoring efforts by the employer indicate that exposures would be 
below the PEL.
    If respirators were mandated at the action level or available upon 
employee request in situations where they are not required under the 
rule, employers would need to have respirators available at all times. 
Moreover, they would need to establish and implement a full respiratory 
protection program for all employees exposed to silica--a considerable 
undertaking for many employers that involves not only the purchase and 
retention of suitable respirators but an ongoing program of training, 
fit-testing, and maintenance. OSHA concludes that ``on request'' 
respirator use or requiring respiratory protection at the action level 
is not a practical or responsible approach to occupational safety and 
health regulation, and requiring such an investment in respirators 
would divert resources from the development and implementation of 
engineering controls that could more effectively reduce exposure levels 
to or below the PEL. Thus, OSHA's approach for reducing employee 
exposure to respirable crystalline silica in this and all other 
standards for air contaminants is to focus on engineering controls, 
rather than additional requirements for respiratory protection. For 
these reasons, OSHA has determined that a requirement for employers to 
provide respirators to employees upon request in situations where they 
are not required under the rule, or a requirement to provide 
respirators to employees exposed at or above the action level, is not 
reasonably necessary and appropriate for this respirable crystalline 
silica rule.
    At the same time, OSHA does not prohibit employers from supplying 
or employees from using respirators outside the requirements of the 
rule. Therefore, although this rule does not include a provision 
providing employees with a right to request and receive respirators 
where not required by the rule, or requiring respiratory protection at 
the action level, employers may continue to provide respirators at the 
request of employees or permit employees to use their own respirators 
in situations where respirator use is not required, as provided for in 
the respiratory protection standard (29 CFR 1910.134(c)(2)(i)). OSHA's 
understanding, however, is that such use beyond what is required in a 
comprehensive OSHA standard is not a common occurrence, and the Agency 
does not expect non-mandated respirator use to proliferate with respect 
to this rule, as might well be the case if a provision requiring 
employers to provide respirators ``on request'' was written into the 
rule and would certainly be the case if the action level were used as 
the trigger for respirator use.
    Industry commenters, including the Construction Industry Safety 
Coalition, OSCO Industries, American Foundry Society, National 
Association of Manufacturers, Glass Packaging Institute, American 
Composite Manufacturers Association, Small Business Administration's 
Office of Advocacy, U.S. Chamber of Commerce, and American 
Subcontractors Association, urged OSHA to consider discarding the 
hierarchy of controls and permitting the use of respirators in lieu of 
engineering and work practices controls in various circumstances, 
including: During short duration tasks performed intermittently 
(Document ID 1992, pp. 3, 5; 2319, p. 115); where exposures exceed the 
PEL for 30 days or less per year (Document ID 4229, p. 11); where 
exposures are below the respirable dust PEL of 5 mg/m\3\ (Document ID 
2380, Attachment 2, p. 24); for unanticipated maintenance issues 
(Document ID 3493, pp. 2-3); for small businesses (Document ID 3588, 
Tr. 3933-3936); for construction employers (Document ID 2187, p. 6; 
2283, p. 3; 2349, p. 5); and for industries using large amounts of 
crystalline silica (e.g., oil and gas operations where hydraulic 
fracturing is conducted) (Document ID 2283, p. 3; 3578, Tr. 1091). 
These comments are discussed in the summary and explanation of Methods 
of Compliance. As indicated in that section, OSHA's longstanding 
hierarchy of controls policy reflects the common assessment among 
industrial hygienists and the public health community that respirators 
are inherently less reliable than engineering and work practice 
controls in reducing employee exposure to air contaminants like 
respirable crystalline silica, and therefore, except in limited 
circumstances, they should not be allowed as an alternative to 
engineering and work practice controls, which are more reliable in 
controlling exposures. Thus, the Agency has not included additional 
situations where respirators are required in the respiratory protection 
paragraph, but as previously discussed, recognizes that, in some 
circumstances, such as certain maintenance and repair activities, 
engineering and work practice controls may not be feasible and the use 
of respiratory protection would be required.
    Paragraph (g)(2) of the general industry and maritime standard 
(paragraph (e)(2) of the standard for construction) requires the 
employer to implement a comprehensive respiratory protection program in 
accordance with OSHA's respiratory protection standard (29 CFR 
1910.134) whenever respirators are used to comply with the requirements 
of the respirable crystalline silica standard. As contemplated in the 
NPRM, a respiratory protection program that complies with the 
respiratory protection standard will ensure that respirators are 
properly used in the workplace and are effective in protecting 
employees. In accordance with that standard, the program must include: 
Procedures for selecting respirators for use in the workplace; medical 
evaluation of employees required to use respirators; fit-testing 
procedures for tight-fitting respirators; procedures for proper use of 
respirators in routine and reasonably

[[Page 16793]]

foreseeable emergency situations; procedures and schedules for 
respirator maintenance; procedures to ensure adequate quality, 
quantity, and flow of breathing air for atmosphere-supplying 
respirators; training of employees in respiratory hazards to which they 
might be exposed and the proper use of respirators; and procedures for 
evaluating the effectiveness of the program (78 FR 56274, 56467 (9/12/
13)).
    Many employers commented that they already have respiratory 
protection programs in place to protect employees from exposures to 
respirable crystalline silica (Document ID 1964; 2183, p. 1; 2276, p. 
5; 2292, p. 2; 2301, Attachment 1, p. 5, 37; 2338, p. 2; 2366, p. 3; 
3577, Tr. 711; 3583, Tr. 2386-2387). The International Union of 
Bricklayers and Allied Craftworkers and the International Union of 
Operating Engineers also indicated that their members' employers have 
established respiratory protection programs (Document ID 2329, p. 7; 
3583, Tr. 2342, 2367).
    The American Association of Occupational Health Nurses, Ameren 
Corporation, 3M Company, and Dr. George Gruetzmacher supported the 
reference to the respiratory protection standard (Document ID 2134; 
2278, p. 3; 2313, p. 6; 2315, p. 4). For example, the 3M Company, which 
manufactures respirators, stated:

    3M believes that by not requiring separate, individual 
respiratory protection provisions for respirable crystalline silica, 
the . . . rule should enhance consolidation and uniformity of the 
1910.134 respirator requirements and could result in better 
compliance concerning the use of respiratory protection. Many of our 
customers use respirators to help protect workers from exposures to 
multiple contaminants and the reference in the respirable 
crystalline silica standard to the requirements of 1910.134 brings 
uniformity that could likely result in better compliance and 
protection for workers with exposures to silica and other materials 
(Document ID 2313, p. 6).

Expressing an opposing view, the National Stone, Sand, and Gravel 
Association commented that the respiratory protection paragraph was 
duplicative of existing requirements in 29 CFR 1910.134 (Document ID 
2327, Attachment 1, p. 11).
    OSHA concludes that referencing the requirements in the respiratory 
protection standard is important for ensuring that respirators are 
properly used in the workplace and are effective in protecting 
employees. Simply cross-referencing these requirements merely brings 
the applicable requirements to the attention of the employer; the 
cross-reference does not add to the employer's existing legal 
obligations, but it makes it more likely that the employer covered by 
this standard will meet all its obligations with regard to providing 
respirators when required to do so. Thus, the Agency has incorporated 
in the rule the reference to the respiratory protection standard that 
was proposed.
    A representative of a local union and individual employees 
recommended specific respirators that they believed should be used to 
protect employees exposed to respirable crystalline silica (Document ID 
1763, p. 3; 1798, p. 6; 2135). OSHA is not singling out silica-specific 
respirators but concludes instead that, for purposes of consistency and 
to ensure that the appropriate respirator is used, the provisions of 
the respiratory protection standard should apply to substance-specific 
standards unless there is convincing evidence that alternative 
respirator selection requirements are justified. The commenters who 
recommended specific respirators did not provide any evidence to 
support their recommendations. As no basis has been established for 
distinguishing respirator requirements for respirable crystalline 
silica from other air contaminants, OSHA finds it appropriate to adopt 
its usual policy of requiring employers to follow the provisions of the 
respiratory protection standard.
    Paragraph (e)(3) of the standard for construction states that, for 
the tasks listed in Table 1 in paragraph (c), if the employer fully and 
properly implements the engineering controls, work practices, and 
respiratory protection described in Table 1, the employer shall be 
considered to be in compliance with paragraph (e)(1) of the standard 
for construction and with the requirements for selection of respirators 
in paragraphs (d)(1)(iii) and (d)(3) of 29 CFR 1910.134. Employers 
following Table 1 must still comply with all other provisions of 29 CFR 
1910.134. Paragraphs (d)(1)(iii) and (d)(3) of 29 CFR 1910.134 require 
the employer to evaluate respiratory hazards in the workplace, identify 
relevant workplace and user factors, and base respirator selection on 
these factors. Because Table 1, in specifying the required respiratory 
protection and minimum APF for a particular task, has already done 
this, employers following Table 1 are considered to be in compliance 
with paragraphs (d)(1)(iii) and (d)(3) of 29 CFR 1910.134 for exposure 
to respirable crystalline silica. While not required for employers 
fully and properly implementing Table 1, paragraph (d)(3)(i)(A) of the 
respiratory protection standard (29 CFR 1910.134), which includes a 
table that can be used to determine the type or class of respirator 
that is expected to provide employees with a particular APF, can help 
employers determine the type of respirator that would meet the required 
minimum APF specified by Table 1. For example, Table 1 requires 
employers to provide employees with respiratory protection with an APF 
of 10 for some of the listed tasks. An employer could consult the table 
in 29 CFR 1910.134(d)(3)(i)(A) to find the types of respirators (e.g., 
half-mask air-purifying respirator) that provide at least an APF of 10.
    Unions, labor groups, and others urged OSHA to include a provision 
in the rule that allows employees to choose a powered air-purifying 
respirator (PAPR) in place of a negative pressure respirator (Document 
ID 2106, p. 3; 2163, Attachment 1, pp. 15-16; 2173, p. 5; 2244, p. 4; 
2253, p. 7; 2256, Attachment 2, pp. 13-14; 2336, p. 7; 2371, Attachment 
1, pp. 33-34; 3581, Tr. 1668-1669; 3955, Attachment 1, p. 2; 4204, pp. 
78-79). They asserted that employees are more likely to get better 
protection from PAPRs, since they are more comfortable and thus, more 
likely to be used. They also argued that this will allow employees who 
may encounter breathing resistance or other difficulty in wearing a 
negative pressure respirator the ability to continue working in a job 
where silica exposures cannot feasibly be controlled below the PEL 
using engineering and work practice controls, without revealing their 
health status or health condition to their employer. They noted that 
previous health standards, such as the standards for asbestos (29 CFR 
1910.1001(g)(2)(ii)) and cadmium (29 CFR 1910.1027(g)(3)(ii)), include 
provisions that allow employees to request and obtain a PAPR without 
revealing their health status or health condition to their employer.
    In some cases, employers are already providing PAPRs to employees 
who request them. The North American Insulation Manufacturers 
Association reported that some member companies provide PAPRs upon 
employee request in certain circumstances, including accommodating 
religious practices and where the work is physically taxing (Document 
ID 4213, pp. 4-5). James Schultz, a former foundry employee from the 
Wisconsin Coalition for Occupational Safety and Health, testified that 
he was able to get his employer to provide a PAPR in some, but not all, 
instances when he requested one (Document ID 3586, Tr. 3201).
    OSHA has long understood that it is good industrial hygiene 
practice to provide a respirator that the employee

[[Page 16794]]

considers acceptable. Under the respiratory protection standard, 
employers must allow employees to select from a sufficient number of 
respirator models and sizes so that the respirator is acceptable to and 
correctly fits the user (29 CFR 1910.134 (d)(1)(iv)). In addition, fit 
testing protocols under the respiratory protection standard require 
that an employee has an opportunity to reject respirator facepieces 
that the employee considers unacceptable (see 29 CFR 1910.134 Appendix 
A). The Agency also recognizes that in some circumstances employees may 
prefer PAPRs over other types of respirators. However, the rulemaking 
record does not provide a sufficient basis for OSHA to conclude that a 
requirement for employers to provide PAPRs upon request would lead to 
any meaningful additional benefit for employees exposed to respirable 
crystalline silica.
    With regard to employees who have difficulty breathing when using a 
negative pressure respirator or cannot wear such a respirator, the 
respiratory protection standard requires employers to provide a PAPR if 
the employee's health is at increased risk if a negative pressure 
respirator is used (29 CFR 1910.134(e)(6)(ii)). Under the medical 
surveillance provisions of this rule, as well as the medical 
determination provisions of the respiratory protection standard (29 CFR 
1910.134(e)(6)), the PLHCP's written medical opinion for the employer 
must contain any recommended limitations on the employee's use of 
respirators. Thus, including a provision in this rule that provides 
employees the ability to choose a PAPR in place of a negative pressure 
respirator would not appreciably add a benefit to what is already 
provided pursuant to required medical determinations. Therefore, OSHA 
finds that a provision specific to this rule permitting employees to 
request and receive a PAPR in place of a negative pressure respirator 
is neither necessary nor appropriate in this rule.
    These requirements are consistent with ASTM E 1132-06, Standard 
Practice for Health Requirements Relating to Occupational Exposure to 
Respirable Crystalline Silica, and ASTM E 2625-09, Standard Practice 
for Controlling Occupational Exposure to Respirable Crystalline Silica 
for Construction and Demolition Activities, the national consensus 
standards for controlling occupational exposure to respirable 
crystalline silica in general industry and in construction, 
respectively. Each of these standards requires respirators to be used 
in work situations in which engineering and work practice controls are 
not sufficient to reduce exposures of employees to or below the PEL. 
Like the consensus standards, where the use of respirators is required, 
the standards that comprise this rule require employers to establish 
and enforce a respiratory protection program, as specified in 29 CFR 
1910.134.

Housekeeping

    Paragraph (h) of the standard for general industry and maritime 
(paragraph (f) of the standard for construction) requires employers to 
adhere to housekeeping practices. This is a new paragraph in the rule, 
but it is derived from the proposed requirements for cleaning methods 
(included in the Methods of Compliance paragraph in the proposed rule) 
and revised in response to further analysis and public comments. The 
requirements apply to all employers covered under this rule, including 
where the employer has fully and properly implemented the control 
methods specified in Table 1 in the standard for construction.
    OSHA proposed a requirement that accumulations of crystalline 
silica be cleaned by high-efficiency particulate air (HEPA)-filter 
vacuuming or wet methods where such accumulations could, if disturbed, 
contribute to employee exposure that exceeds the PEL. The proposed rule 
would also have prohibited the use of compressed air, dry sweeping, and 
dry brushing to clean clothing or surfaces contaminated with 
crystalline silica where such activities could contribute to exposures 
exceeding the PEL. OSHA included these provisions in the proposed rule 
because evidence shows that use of HEPA-filtered vacuums and wet 
methods instead of dry sweeping, dry brushing and blowing compressed 
air effectively reduces worker exposure to respirable crystalline 
silica during cleaning activities. For example, a study of Finnish 
construction workers compared respirable crystalline silica exposure 
levels during dry sweeping to exposure levels when using alternative 
cleaning methods. Compared with dry sweeping, estimated worker 
exposures were about three times lower when workers used wet sweeping 
and five times lower when they used vacuums (Document ID 1163).
    Some commenters, including the International Union of Bricklayers 
and Allied Craftworkers (BAC), the United Steelworkers (USW), the 
Building and Construction Trades Department, AFL-CIO (BCTD), the United 
Automobile, Aerospace and Agricultural Implement Workers of America 
(UAW), BlueGreen Alliance (BGA), and Upstate Medical University, 
expressed support for the proposed requirement to use HEPA-filtered 
vacuums and wet methods and to prohibit the use of compressed air and 
dry sweeping for cleaning activities (e.g., Document ID 2282, 
Attachment 3, pp. 2, 18-19; 2329, p. 6; 2336, pp. 8-10; 2371, Comment 
1, pp. 32-33; 2176, p. 3; 2244, p. 4). For example, UAW stated that the 
prohibitions on the use of compressed air and dry sweeping constitute 
sound industrial hygiene and are necessary to ensure that dust is 
controlled (Document ID 2282, Attachment 3, p. 18). Similarly, BCTD 
argued that the record firmly supports the use of HEPA-filtered vacuums 
and wet methods in lieu of compressed air and dry sweeping. BCTD 
pointed to specific studies referenced in OSHA's Preliminary Economic 
Analysis (PEA) that it believes demonstrate that performing 
housekeeping duties using compressed air or dry sweeping is a major 
source of silica exposure in a number of work operations (Document ID 
2371, p. 34). BCTD also noted and agreed with studies in the PEA that 
recommend reducing silica exposure by eliminating these practices and 
instead relying on HEPA-filtered vacuums and wet methods (Document ID 
2371, p. 34). Based on this evidence, BCTD agreed with the inclusion of 
the cleaning provisions. However, as discussed more extensively below, 
BCTD, and many of the other commenters that supported these provisions, 
argued that OSHA should expand the requirement to apply to cleaning 
whenever silica dust is present, not only where employee exposure could 
exceed the PEL (e.g., Document ID 2240, p. 3; 2256, Attachment 2, p. 
13; 2282, Attachment 3, p. 2; 4204, p. 77).
    The National Institute for Occupational Safety and Health (NIOSH) 
also supported OSHA's proposed requirement to use wet methods and HEPA-
filtered vacuums and prohibit the use of dry sweeping and compressed 
air during cleaning activities. In its written comments and testimony 
during the hearings, NIOSH cited U.S. Bureau of Mines research 
indicating that dry sweeping can increase respirable dust exposures, 
and provided several recommendations, including using water to wash 
down facilities that may have silica contamination, and using portable 
or centralized vacuum systems to clean off equipment (Document ID 2177, 
Attachment B, p. 38; 3579, p. 142).
    Other commenters, such as Ameren, Acme Brick, the American Iron and 
Steel Institute (AISI), Fann Contracting, Inc., Leading Builders of 
America (LBA), Edison Electric Institute (EEI),

[[Page 16795]]

the National Association of Home Builders (NAHB), Eramet and Bear 
Metallurgy Company, Accurate Castings, the Asphalt Roofing 
Manufacturers Association (ARMA), the Small Business Administration's 
Office of Advocacy, the Glass Association of North America (GANA), the 
National Association of Manufacturers (NAM), the American Foundry 
Society (AFS), the Ohio Cast Metals Association (OCMA), the Tile 
Council of North America (TCNA), the North American Insulation 
Manufacturers Association (NAIMA), the Non-Ferrous Founders Society 
(NFFS), the National Concrete Masonry Association (NCMA), and the 
American Society of Safety Engineers (ASSE), objected to the proposed 
provisions (e.g., Document ID 2023, pp. 5-6; 2082, pp. 5-7; 2116, 
Attachment 1, pp. 9-10, 32-33; 2261, p. 3; 2269, pp. 4, 22-23; 2291, 
pp. 2, 13, 18-20, 27; 2296, pp. 9, 41-42; 2315, p. 8; 2339, p. 9; 2349, 
pp. 4-5; 2357, pp. 7, 24-25; 2381, p. 2; 3432, p. 3; 3492, p. 2; 2119, 
Attachment 3, p. 7; 2215, p. 9; 2248, p. 8; 2279, pp. 7-8; 2348, 
Comment 1, p. 37; 2363, p. 3; 3490, p. 3; 3581, Tr. 1726-1727; 4213, p. 
5). Many of these commenters cited problems with the use of wet methods 
or HEPA-filtered vacuums in particular circumstances, or noted specific 
circumstances where they believed dry sweeping or using compressed air 
was necessary.
    For example, AISI indicated that using wet methods in areas of 
steel making facilities where molten metal is present creates the 
potential for a significant and immediate safety hazard from steam 
explosions (Document ID 2261, p. 3; 3492, p. 2). The National Concrete 
Masonry Association argued that wet methods cannot generally be used in 
concrete block and brick plants:

    In general, wet methods to control dust are NOT appropriate in 
the concrete masonry as a replacement for dry-sweeping . . . Not 
only do wet floors create fall hazards, any dust or debris that 
contains cement dust will react and harden in the presence of water, 
creating additional problems in concrete block production facilities 
(Document ID 2279, pp. 7-8).

EEI and Ameren indicated that the use of wet methods can also cause fly 
ash to harden (Document ID 2357, pp. 24-25; 2315, p. 8).
    NAHB indicated that use of wet methods in residential construction 
would damage many surfaces and could lead to structural problems, 
indoor air quality degradation, and the development of molds (Document 
ID 2296, p. 37). It argued that there are many circumstances in 
residential construction where dry sweeping is the only alternative for 
cleanup activities (Document ID 2296, pp. 41-42). LBA indicated that 
HEPA-filter vacuums will not collect large debris and that, during the 
collection process, dirt will clog the HEPA filter, preventing 
cleaning. It stressed that dry sweeping must be used (Document ID 2269, 
pp. 4, 22-23). Ameren and EEI argued that dry sweeping should be 
allowed because wet methods cannot be used around certain electrical 
equipment and when temperatures are below freezing (Document ID 2315, 
p. 8; 2357, pp. 7, 24-25). Fann Contracting said that it is necessary 
to dry sweep at the end of the milling process when milling roadways in 
order to clean the loose leftover material. It indicated that if water 
is used, it would create a thin layer of mud on the bottom of the 
milled trench, which would interfere with the paving process (Document 
ID 2116, Attachment 1, pp. 9-10, 32-33).
    Commenters representing foundries argued that wet methods and HEPA-
filtered vacuuming were not appropriate for cleaning in foundries. For 
example, Accurate Castings explained that wet methods would result in 
water going into the shell sand mold and would eventually lead to an 
explosion when molten metal enters the mold. It stressed that it must 
use compressed air for these applications (Document ID 2381, p. 2). 
Similarly, ESCO Corporation commented that it cannot use water in 
foundries due to potential for fire and explosion hazards. ESCO 
Corportation stressed that it also must use compressed air to clean 
castings (Document ID 3372, pp. 2-3). AFS also argued that the use of 
wet methods in foundries increases the likelihood of explosions as well 
as tripping hazards (Document ID 3490, p. 3). OCMA argued that vacuums 
can cause damage to molds and using wet methods would damage equipment, 
make floors slippery, and cause explosions (Document ID 2119, 
Attachment 3, p. 7). NFFS argued that compressed air is ``the only 
viable means of cleaning complex or intricate castings'' (Document ID 
2247, p. 8; 2248, p. 8). AFS argued that a ban on dry sweeping would 
require the vacuuming of hundreds of tons per week in many foundry 
operations, and that collecting this amount of sand with a vacuum 
system is not feasible. AFS also expressed concern that the proposed 
rule would prohibit use of operator-driven power (dry) sweepers in 
foundries, arguing that power sweepers substantially reduce the release 
of fugitive dust from aisles and other vehicle traffic areas and that 
these machines cannot be replaced with wet sweepers because the 
quantity of material handled would gum up the sweeping mechanism with 
sludge (Document ID 2379, Attachment B, pp. 33-34).
    Several commenters indicated that compressed air is needed to clean 
difficult to reach places (e.g., Document ID 2215, p. 9; 2279, pp. 7-8; 
3581, Tr. 1726; 2023, p. 5; 2348, Comment 1, p. 37; 3544, pp. 15-16; 
4213, pp. 5; 2119, Attachment 3, p. 7). For example, GANA stressed that 
it is ``not technologically feasible to prohibit completely the use of 
compressed air for clean-up,'' because tight spaces and hard-to-reach 
crevices can only be cleaned using compressed air (Document ID 2215, p. 
9). NAM testified to the need to use compressed air in space-restricted 
situations and where there is a potential for explosions when using 
water and there are no other alternatives (Document ID 3581, Tr. 1726). 
Acme Brick also indicated that compressed air must be used in tight 
spaces or under equipment because these areas cannot be accessed by 
brooms or vacuums (Document ID 2023, p. 5).
    After reviewing the evidence in the record, OSHA concludes that use 
of wet methods and HEPA-filter vacuums, as proposed, is highly 
effective in reducing respirable crystalline silica exposures during 
cleaning and that compressed air, dry sweeping, and dry brushing can 
contribute to employee exposures. However, OSHA finds convincing 
evidence that wet methods and HEPA-filtered vacuums are not safe and 
effective in all situations. Therefore, the Agency has revised the 
proposed language to take these situations into account. Paragraph 
(h)(1) of the standard for general industry and maritime (paragraph 
(f)(1) for construction) allows for the use of dry sweeping and dry 
brushing in the limited circumstances where wet methods and HEPA-
filtered vacuuming are not feasible. Paragraph (h)(2) of the standard 
for general industry and maritime (paragraph (f)(2) for construction) 
allows employers to use compressed air for cleaning where the 
compressed air is used in conjunction with a ventilation system that 
effectively captures the dust cloud created by the compressed air, or 
where no alternative method is feasible. These limited exceptions will 
encompass the situations described above by commenters, and give them 
the necessary flexibility in permitting the use of compressed air, dry 
sweeping, or dry brushing in situations where wet methods or HEPA-
filtered vacuums are infeasible, or where the dust cloud created by use 
of compressed air is

[[Page 16796]]

captured and therefore does not present a hazard to employees. Thus, in 
situations where wet methods or HEPA-filtered vacuuming would not be 
effective, would cause damage, or would create a hazard in the 
workplace, the employer is not required to use these cleaning methods. 
OSHA concludes that these limited exceptions balance the need to 
protect employees from exposures caused by dry sweeping, dry brushing, 
and the use of compressed air with stakeholder concerns about the need 
to use such methods under certain circumstances.
    Although OSHA is allowing for dry sweeping and dry brushing and the 
use of compressed air for cleaning clothing and surfaces under these 
limited circumstances, the Agency anticipates that these circumstances 
will be extremely limited. The ``unless'' clause indicates that the 
employer bears the burden of showing that wet methods are not feasible 
in a particular situation, and OSHA expects that the vast majority of 
operations will use wet methods that minimize the likelihood of 
exposure. Where the employer uses dry sweeping, therefore, the employer 
must be able to demonstrate that HEPA-filtered vacuuming, wet methods, 
or other methods that minimize the likelihood or exposure are not 
feasible. Similarly, where compressed air is used to clean clothing and 
surfaces without a ventilation system designed to capture the dust 
cloud created, the employer must be able to demonstrate that no 
alternative cleaning method is feasible.
    OSHA has also revisited the triggers for these provisions based on 
stakeholder comments. Some stakeholders disagreed with triggering these 
provisions based on the PEL. For example, the American Federation of 
State, County, and Municipal Employees (AFSCME), the American 
Federation of Labor and Congress of Industrial Organizations (AFL-CIO), 
BCTD, BAC, UAW, USW, and others argued that dry sweeping and use of 
compressed air should be prohibited at any exposure level, not just 
where the use of such measures contributes to exposures that exceed the 
PEL (e.g., Document ID 2142, p. 3; 2257, Attachment 2, p. 13; 2282, 
Attachment 3, pp. 18-19; 2329, p. 6; 2336, p. 10; 2371, Comment 1, pp. 
32-33). AFL-CIO stated:

    OSHA has determined that exposure at the PEL still poses a 
significant risk to workers. All feasible efforts should be made to 
reduce those risks. OSHA should follow the well-established approach 
in its other health standard[s] and prohibit practices of dry 
sweeping, [use of] compressed [air] and require HEPA-filter[ ] 
vacuuming or wet methods whenever silica dust is present (Document 
ID 2257, Attachment 2, p. 13).

    Similarly, AFSCME indicated that there is no reason why cleaning 
methods need to be tied to the PEL. It argued that requiring that all 
accumulations be dealt with in a uniform way would provide clarity for 
employers and employees alike (Document ID 2142, p. 3). BCTD argued 
that OSHA's proposed requirements would be unenforceable because they 
are tied to overexposure (Document ID 2371, Attachment 1, p. 33). 
Finally, AFL-CIO also recommended that OSHA expand the proposed 
requirements to require that accumulations of dust be kept as low as 
practicable. It noted that this requirement has appeared in previous 
OSHA health standards that regulate exposure to dusts, such as asbestos 
(29 CFR 1910.1001), lead (29 CFR 1910.1025), and cadmium (29 CFR 
1910.1027).
    On the other hand, the Precast/Prestressed Concrete Institute (PCI) 
argued that a general prohibition on the use of compressed air, dry 
brushing, and dry sweeping to clean areas where silica-containing 
material has accumulated is too broad, and not directly related to a 
particular exposure risk. It maintained that the use of compressed air 
and dry sweeping should be permitted as long as silica exposures are 
below the PEL (Document ID 4029, Cover Letter 1, p. 3). Similarly, the 
National Tile Contractors Association (NTCA) and TCNA both recommended 
that the proposed language be changed to read as follows:

    To the extent practical compressed air, dry sweeping, and dry 
brushing shall not be used to clean clothing or surfaces 
contaminated with crystalline silica where such activities could 
contribute to employee exposure to respirable crystalline silica 
that exceeds the PEL (Document ID 2267, p. 3; 2363, p. 3).

    After consideration of these comments, OSHA has decided to revise 
the trigger for the housekeeping provisions in the rule to apply to 
situations where dry sweeping, dry brushing or use of compressed air 
could contribute to employee exposure to respirable crystalline silica, 
regardless of whether that exposure exceeds the PEL. OSHA finds this 
change is necessary because the risk of material impairment of health 
remains significant at and below the revised PEL of 50 [mu]g/m\3\, 
including at the new action level of 25 [mu]g/m\3\. By triggering the 
housekeeping provisions wherever the use of dry sweeping, dry brushing, 
and compressed air could contribute to employee exposures, OSHA aims to 
minimize this risk. The Agency concludes that the limited exceptions 
discussed above not only balance the concerns of employers with the 
need to protect employees, but align the rule with the realities of the 
workplace, which do not always lend themselves to the method that 
produces the lowest silica exposure.
    OSHA has decided not to include an affirmative requirement to clean 
accumulations of crystalline silica that could, if disturbed, 
contribute to employee exposure that exceeds the PEL. In addition, the 
Agency has determined that it is not appropriate for the respirable 
crystalline silica rule to require accumulations of dust to be kept at 
the lowest level practicable. As noted above, OSHA recognizes that 
exposure to respirable crystalline silica is hazardous at 
concentrations below the PEL. However, crystalline silica is ubiquitous 
in many work environments. Crystalline silica is a component of the 
soil and sand at many construction sites and other outdoor workplaces, 
and may be present in large quantities at many other workplaces such as 
foundries and oil and gas drilling sites where hydraulic fracturing is 
performed. For purposes of cleaning, the employer may not be able to 
distinguish large crystalline silica particles from the fine particles 
which can, if airborne, be respirable. In many cases, the employer may 
not be able to distinguish crystalline silica particles from other 
workplace dusts. Because of these factors, many unique to respirable 
crystalline silica, OSHA is convinced that the best approach to address 
potentially hazardous exposures from cleaning is by requiring proper 
housekeeping practices to minimize exposure to respirable crystalline 
silica.
    OSHA also received a number of miscellaneous comments on the 
proposed provisions, including suggestions for items the Agency should 
or should not include in the final rule and questions about the 
application of the proposed provisions to particular situations. For 
example, ARMA argued that OSHA should not require HEPA filters on 
central vacuum systems that discharge outdoors or into a non-occupied 
area, such as a baghouse (Document ID 2291, pp. 19-20). GPI also 
indicated it uses central vacuum systems, and argued that OSHA should 
allow for vacuum systems that discharge outside the facility (Document 
ID 2290, pp. 4-5). OSHA agrees that a prohibition on central vacuum 
systems that discharge respirable crystalline silica outside of the 
workplace is unnecessary, because such systems do not contribute to 
employee exposure. OSHA clarifies that the rule therefore

[[Page 16797]]

allows for use of vacuum systems that discharge respirable crystalline 
silica outside of the workplace. These requirements are similar to 
housekeeping requirements in other OSHA health standards, such as the 
standards for lead (29 CFR 1910.1025) and cadmium (29 CFR 1910.1027). 
Discharge of respirable crystalline silica from such systems may be 
subject to environmental regulations; see Section XIV, Environmental 
Impacts.
    Occupational & Environmental Health Consulting Services (OEHCS) 
urged OSHA to require vacuums that meet the definition of a Portable 
High-Efficiency Air Filtration (PHEAF) device (Document ID 1953, 
Comment 1, pp. 4-6). This suggested revision would involve a 
requirement for field testing of portable air filtration devices using 
a laser particle counter to ensure that HEPA filters function as 
intended. OEHCS argued that, in many cases, HEPA filters do not perform 
effectively in the field due to inadequate, damaged, or deteriorating 
sealing surfaces; replacement filters that do not fit correctly; filter 
cabinets that are damaged; filters that are punctured; and other 
problems (Document ID 1953, Comment 1, p. 2). OEHCS further indicated 
that it is participating in an ongoing, multi-year research effort with 
the National Institutes of Health to test HEPA-filtered equipment 
(Document ID 1953, Comment 1, p. 2). However, OEHCS did not provide 
documentation to support the use and effectiveness of meeting the 
requirements and definition of this device, nor is there other evidence 
in the rulemaking record supporting such a requirement. OSHA encourages 
employers to ensure that HEPA filters function as intended in the 
field. However, lacking adequate documentation and support in the 
record, OSHA has concluded that it is not appropriate to include a 
requirement that HEPA vacuums meet the PHEAF standards in the rule.
    OSHA also received a few comments related to the use of compressed 
air, dry sweeping, and dry brushing to clean clothing. Specifically, 
NIOSH and ASSE maintained that there are ways that clothing can be 
safely cleaned using compressed air. The two organizations advocated 
for the use of clothes cleaning booths, also referred to as mobile air 
showers (Document ID 2177, Attachment B, pp. 15, 38; 3403, p. 5; 2339, 
p. 9). This technology uses compressed air to clean clothes by blowing 
dust from an employee's clothing in an enclosed booth. Dust is blown 
out of the employee's breathing zone and is captured by a filter. NIOSH 
argued that the booths adequately capture the dust and prevent exposure 
to employees and the environment (Document ID 3403, p. 5). OSHA 
recognizes that this technology may be useful for cleaning dust off of 
clothing, and the rule does not prohibit the use of such systems. 
Clothes cleaning booths that use compressed air to clean clothing are 
permitted under the rule, as long as the compressed air is used in 
conjunction with a ventilation system that effectively captures the 
dust cloud created by the compressed air. The provision has been 
modified from that proposed to clearly allow the use of compressed air 
in conjunction with a ventilation system that effectively captures the 
dust cloud that is created, preventing it from entering the employee's 
breathing zone.
    In addition, the American Subcontractors Association (ASA) offered 
a comment related to dry brushing. It argued that the term ``dry 
brushing'' could be misunderstood, and that an employer could receive a 
citation if an employee reflexively brushes visible dust off clothing 
(Document ID 2187, p. 6). OSHA's intent in the proposed rule was to 
restrict dry brushing activity that was comparable to dry sweeping, 
such as using a brush as a tool to clean clothing or surfaces. OSHA 
clarifies that the rule does not prohibit employees from using their 
hands to remove small amounts of visible dust from their clothing.
    Finally, OSHA received comments on how often or at what point 
employers need to clean up dust in their facility. For instance, 
HalenHardy, a firm that provides products and services to limit 
exposures to dangerous dusts, argued that there should be some visible 
evidence of silica dust in order to require cleaning (Document ID 3588, 
Tr. 3920-3922). NCMA commented that dry sweeping can produce dust and 
indicated that best practices suggest that it is important to prevent 
the dust or debris from reaching the floor. If not cleaned regularly, 
this can lead to buildups of dust on the floor (Document ID 2279, p. 
7).
    The proposed rule would have required accumulations of crystalline 
silica to be cleaned by HEPA-filtered vacuuming or wet methods where 
such accumulations could, if disturbed, contribute to employee exposure 
to respirable crystalline silica that exceeds the PEL. As explained 
above, OSHA's final rule does not require employers to clean up dust. 
However, OSHA agrees that housekeeping is an important work practice to 
be used to limit employee exposures. And, as discussed in Chapter IV of 
the Final Economic Analysis and Final Regulatory Flexibility Analysis, 
some employers will need to perform housekeeping in order to limit 
employee exposures to the PEL. In recognition of this fact and because 
some cleaning methods can contribute to employee exposure, OSHA has 
included housekeeping as one of the items employers must address in 
their written exposure control plans (see the summary and explanation 
of Written Exposure Control Plan).
    Moreover, for employers following the general industry and maritime 
standard and, in construction, for tasks not listed in Table 1, or 
where the employer does not fully and properly implement the control 
methods described in Table 1, the rule requires employers to assess the 
exposure of each employee who is or may reasonably be expected to be 
exposed to respirable crystalline silica at or above the action level. 
Where exposure assessment reveals that an employee's exposure exceeds 
the PEL, the rule requires employers to use engineering and work 
practice controls to reduce and maintain employee exposure to or below 
the PEL, unless the employer can demonstrate that such controls are not 
feasible. Good housekeeping is one such work practice control that 
employers should consider. And, as NCMA suggests, employers may choose 
to clean up dust regularly as a best practice.
    In addition, paragraph (c) of the standard for construction 
includes several housekeeping provisions that apply to employers who 
choose to follow Table 1. For instance, paragraphs (c)(1)(vii) and 
(c)(1)(viii) of the standard for construction require employers whose 
employees are engaged in a task using handheld or stand-mounted drills 
(including impact and rotary hammer drills) or dowel drilling rigs for 
concrete to use a HEPA-filtered vacuum when cleaning holes. Similarly, 
under paragraph (c)(1)(xiii), when using a walk-behind milling machine 
or floor grinder indoors or in an enclosed area, milling debris must be 
cleaned up using a HEPA-filtered vacuum prior to making a second pass 
over an area. This prevents the milling debris from interfering with 
the seal between machine and floor and minimizes the gap. Additionally, 
it prevents debris from being re-suspended and acting as another source 
of exposure.
    If an employer chooses to follow paragraph (c) of the standard for 
construction, then the employer must implement any applicable 
housekeeping measures specified in Table 1. An employer who does not do 
so has not fully and properly implemented the controls identified on 
Table 1 and, thus, will be required to assess and limit the

[[Page 16798]]

exposure of employees in accordance with paragraph (d). For example, if 
an employer has an employee who is using a handheld or stand-mounted 
drill, the employee must use a HEPA-filtered vacuum when cleaning 
holes. Any method for cleaning holes can be used, including the use of 
compressed air, if a HEPA-filtered vacuum is used to capture the dust. 
If a HEPA-filtered vacuum is not used when cleaning holes, then the 
employer must assess and limit the exposure of that employee in 
accordance with paragraph (d).
    While the paragraph on housekeeping (paragraph (f) of the 
construction standard) also applies when employers are following 
paragraph (c), the employer must ensure that all of the engineering 
controls and work practices specified on Table 1 are implemented. For 
example, paragraph (f)(2)(i) of the construction standard permits the 
use of compressed air when used in conjunction with a ventilation 
system that effectively captures the dust cloud. However, to fully and 
properly implement the controls on Table 1, an employer using 
compressed air when cleaning holes drilled by handheld or stand-mounted 
drills or dowel drilling rigs for concrete must use a HEPA-filtered 
vacuum to capture the dust, as specified in paragraphs (c)(1)(vii) and 
(c)(1)(viii), not just a ventilation system as specified in paragraph 
(f)(2)(i).
    The housekeeping requirements of the rule are generally consistent 
with the provisions of the industry consensus standards, ASTM E 1132-
06, Standard Practice for Health Requirements Relating to Occupational 
Exposure to Respirable Crystalline Silica, and ASTM E 2626-09, Standard 
Practice for Controlling Occupational Exposure to Respirable 
Crystalline Silica for Construction and Demolition Activities. Both 
consensus standards specify that compressed air shall not be used to 
blow respirable crystalline silica-containing materials from surfaces 
or clothing, unless the method has been approved by an appropriate 
Regulatory agency (4.4.3.3. and 4.4.3.2, respectively). Both consensus 
standards also list HEPA vacuums, water spray, and wet floor sweepers 
among available means to reduce exposure to dust (4.4.3.6. and 4.4.3.5, 
respectively). In addition, ASTM E 1132-06 includes restrictions on dry 
sweeping (4.4.3.2).

Written Exposure Control Plan

    Paragraph (f)(2) of the standard for general industry and maritime 
(paragraph (g) of the standard for construction) sets forth the 
requirements for written exposure control plans, which describe methods 
used to identify and control workplace exposures, such as engineering 
controls, work practices, and housekeeping measures. OSHA did not 
propose a requirement for a written exposure control plan, but raised 
it as an issue in the preamble of the Notice of Proposed Rulemaking 
(NPRM) in Question 53 under Methods of Compliance (78 FR 56273, 56289 
(9/12/13)). Written exposure control plans are included in ASTM 
International (ASTM) standards, E 1132-06, Standard Practice for Health 
Requirements Relating to Occupational Exposure to Respirable 
Crystalline Silica (Section 4.2.6) and E 2625-09, Standard Practice for 
Controlling Occupational Exposure to Respirable Crystalline Silica for 
Construction and Demolition Activities (Section 4.2.5), and in a draft 
standard by the Building and Construction Trades Department, AFL-CIO 
(BCTD) (Document ID 1466, p. 2; 1504, p. 2; 1509, pp. 3-4).
    The only written plan that OSHA proposed was an access control 
plan, which was an alternative approach to establishing regulated 
areas; it described methods for identifying areas where exposures 
exceeded the permissible exposure limit (PEL), limiting access to those 
areas, communicating with others on the worksite, and providing 
personal protective equipment (PPE) to individuals entering those 
areas. Several stakeholders commented on the proposed written access 
control plans, whether or not the rule should contain a written plan, 
and their preference for the type of written plan.
    A number of commenters questioned the practicality of a written 
access control plan in workplaces with continually changing tasks, 
conditions, or materials, which they argued can lead to the need for 
multiple plans and subsequent costs. The National Stone, Sand, and 
Gravel Association (NSSGA) commented that written access control plans 
and establishing boundaries are not feasible in many workplaces, such 
as aggregate facilities or large construction sites, because of varying 
silica amounts in materials (Document ID 2327, Attachment 1, p. 20). 
The Construction Industry Safety Coalition (CISC) stated that a written 
access control plan is impractical in construction and especially 
difficult and costly for small businesses because a different plan 
would need to be developed for each project, as a result of changing 
materials, tasks, and environmental conditions (Document ID 2319, pp. 
5-6, 91-92). Associated Builders and Contractors, Inc. (ABC), 
Associated General Contractors of America, and American Society of 
Safety Engineers (ASSE) expressed similar concerns about constantly 
changing conditions on construction sites (Document ID 2289, pp. 6-7; 
2323, p. 1; 4201, p. 2). The National Federation of Independent 
Business and Leading Builders of America also expressed concerns about 
time and resource burdens that a requirement for a written access 
control plan would impose on construction companies or small businesses 
(Document ID 2210, Attachment 1, p. 7; 2269, p. 22). ABC and CISC 
further stated that a written access control plan is not needed if 
employees are trained (Document ID 2289, pp. 6-7; 4217, p. 25).
    CISC noted that section 4.2.5 of the ASTM standard E 2625-09 limits 
the need for a written exposure control plan to areas where 
overexposures are persistent, and contemplated that it is not needed 
when the PEL may be exceeded on a particular day because of conditions 
such as weather or silica content in a material. CISC stated that 
OSHA's requirement for a regulated area or written access control plan 
when exposures can reasonably be expected to exceed the PEL deviated 
from section 4.2.5 of the ASTM standard (Document ID 2319, p. 89; 1504, 
p. 2). OSHA clarifies that a written access control plan, which 
describes specified methods for limiting access to high-exposure areas, 
is different from a written exposure control plan, which can address 
specified protections for controlling exposure other than limiting 
access to high-exposure areas.
    Commenters representing industry, labor, and employee health 
advocate groups addressed the issue of what, if any, type of written 
plan should be required and what level of respirable crystalline silica 
exposure should trigger that requirement. Some industry representatives 
favored a written access control plan over a regulated area, while 
others opposed a written exposure control plan. For example, in 
comparing regulated areas and the written access control plan, Edison 
Electric Institute favored the flexibility of the written access 
control plan and stated that it might use that option in larger areas 
or for activities that can change over time. It opposed a written 
exposure control plan, asserting that the training required by OSHA's 
hazard communication standard (HCS) was sufficient to keep employees 
informed (Document ID 2357, pp. 33, 37). The Non-Ferrous Founders' 
Society expressed concerns about costs if a consulting industrial 
hygienist would need to be hired to develop a written access control 
plan (Document ID 2248, p. 13). The National Association of Home 
Builders (NAHB) stated that some of its members would

[[Page 16799]]

prefer a written access control plan over regulated areas, while other 
members expressed concern that developing a written access control plan 
might be difficult for many small companies. NAHB also commented that 
many small companies would not have the knowledge to develop a written 
exposure control plan and would have to hire a professional to develop 
it. NAHB opposed a written exposure control plan, stating that a 
standard checklist was adequate for protecting employees from exposure 
(Document ID 2296, pp. 40 and 41). On the other hand, National 
Electrical Carbon Products (NECP) commented that if OSHA required a 
written plan, NECP would prefer an exposure control plan rather than an 
access control plan. It stated that OSHA's proposed access restrictions 
do not relate to the goal of ensuring compliance with the PEL (Document 
ID 1785, pp. 6-7).
    Commenters from labor organizations and employee health advocate 
groups supported the inclusion of a written exposure control plan. For 
example, BCTD stated that the proposed written access control plan 
could be used as a starting point for the development of a written 
exposure control plan, which it said should be required for every 
employer that has employees who may be exposed to respirable 
crystalline silica (Document ID 2371, Attachment 1, pp. 14-16). 
International Union of Operating Engineers (IUOE), Public Citizen, 
American Federation of Labor and Congress of Industrial Organizations 
(AFL-CIO), and International Union of Bricklayers and Allied 
Craftworkers (BAC) also supported a requirement for a written plan for 
all covered employers and not just those with regulated areas or 
exposures exceeding the PEL (Document ID 2262, p. 42; 2249, p. 3; 4204, 
p. 62; 4219, pp. 25-26; 4223, p. 119).
    Other commenters, such as ASSE, favored a written exposure control 
plan for suspected or documented overexposure scenarios (Document ID 
2339, p. 8). The National Industrial Sand Association (NISA) originally 
opposed a written exposure control program in its prehearing comments 
(Document ID 2195, p. 38). However, in its post-hearing comments, it 
supported one, stating that formulating and writing down an exposure 
control program would ensure that an employer thinks through the 
engineering and administrative controls required to achieve compliance 
in situations with persistent overexposures. NISA also stated that the 
plan would help employers defend against potential liability by 
documenting due care (Document ID 4208, pp. 20-21).
    The American Foundry Society (AFS) disagreed with the need for a 
separate written exposure control plan and instead called for planning 
as part of other business initiatives. It supported written exposure 
control plans in enforcement situations. AFS favored an approach 
similar to that in the ASTM standard. AFS stated that the ASTM's 
approach, which involves identifying and analyzing dust sources in 
scenarios with overexposures to determine effective controls, was more 
effective in reducing exposures than requiring controls to be installed 
by a certain date (Document ID 2379, Appendix 1, pp. 61-62; 4229, p. 
26).
    Advocates of written exposure control plans explained why they 
supported those plans. The National Institute for Occupational Safety 
and Health (NIOSH) stated that written exposure control plans could be 
a simple mechanism for ensuring performance of maintenance checks and, 
for construction employers, maintaining Table 1 conditions (Document ID 
2177, Attachment B, pp. 16-17). Dr. Paul Schulte, Director of the 
Education and Information Division at NIOSH, testified that ``. . . a 
written plan would greatly improve reliability of the protection 
provided.'' (Document ID 3403, p. 5). AFL-CIO, NISA, and BCTD agreed 
(Document ID 4204, p. 61; 4208, pp. 20-21; 4223, p. 74). Eileen Betit, 
representing BCTD, testified:

    Written exposure control plans are important for identifying 
operations that will result in exposures, the specific control 
measures, and how they will be implemented and the procedures for 
determining if controls are being properly used and maintained. Such 
plans also facilitate the communication of this information to other 
employers on multi-employer worksites so that they, in turn, can 
take steps to protect their employees. Without such plans, there's 
no assurance that employers and employees will take a systematic and 
comprehensive approach to identifying, controlling, and sharing 
information about silica exposures on job sites (Document ID 3581, 
Tr. 1569-1570).

The United Steelworkers (USW), Public Citizen, the United Automobile, 
Aerospace and Agricultural Implement Workers of America (UAW), and AFL-
CIO also supported a requirement for a written exposure control plan as 
a method to continually, systematically, or comprehensively identify or 
control exposures (Document ID 2336, p. 9; 2249, p. 2; 2282, Attachment 
3, p. 17; 4204, p. 60). NIOSH, Public Citizen, and BAC also stated that 
written exposure control plans are a useful way to communicate 
protections to employees (Document ID 2177, Attachment B, pp. 16-17; 
2249, p. 3; 2329, p. 5).
    BlueGreen Alliance, UAW, USW, and AFL-CIO also supported a written 
plan because requiring the written plan would be consistent with the 
many other OSHA substance-specific standards that include written plans 
or programs (Document ID 2176, p. 3; 2282, Attachment 3, p. 17; 3584, 
Tr. 2540; 4204, p. 62). In addition, commenters observed that other 
U.S. and Canadian regulatory agencies require written plans. Frank 
Hearl, Chief of Staff at NIOSH, stated that the Mine Safety and Health 
Administration requires a dust control plan to be filed at coal mines 
(Document ID 3579, Tr. 235-236). In addition, AFL-CIO and BCTD noted 
that written dust or silica control plans are included in a proposed 
standard for the Canadian Province of British Columbia and a standard 
promulgated in the Canadian Province of Newfoundland (Document ID 4204, 
p. 61; 4223, p. 73 Fn. 14; 4072, Attachment 38, pp. 6-7, Attachment 41, 
p. 7).
    BCTD stated that a requirement for a written exposure control plan 
would not be unduly burdensome to employers because creating such plans 
is an extension of planning functions in construction (Document ID 
4223, pp. 74-80). In fact, several hearing participants testified that 
written safety or hazard control plans are already being developed and 
used in the construction industry (Document ID 4223, pp. 74-80; 3580, 
Tr. 1383-1385; 3583, Tr. 2267-2268, 2385; 3585, Tr. 3093-3094; 3587, 
Tr. 3560). For example, Kevin Turner, Director of Safety at Hunt 
Construction Group and representing CISC testified: ``. . . we require 
a site-specific safety plan which addresses the hazards dealt with in 
that [particular] contractor's scope of work.'' (Document ID 3580, Tr. 
1383).
    In addition, written plans are consistent with general industry 
practices. For example, the National Service, Transmission, 
Exploration, and Production Safety Network (STEPS Network), whose 
members are involved in the oil and gas industry, recommends a written 
plan that describes how exposures to respirable crystalline silica will 
be reduced or prevented (Document ID 4024, Attachment 2, p. 1). Member 
companies of the National Ready Mix Concrete Association, who hire 
third-party contractors to chip out their drum mixers, follow strict 
written practices and procedures to ensure that exposures do not exceed 
the PEL. Specifically, they require the contractors to submit to them a 
company-approved safety and health policy and procedures and plans 
(Document ID 2305, pp. 8-9). AFL-CIO

[[Page 16800]]

submitted to the record a silica dust control plan developed by Sonic 
Drilling (Document ID 4072, Attachment 11).
    BCTD stressed that preparing a written exposure control plan does 
not have to be burdensome and, along with BAC and AFL-CIO, pointed to 
online tools that are available to help users create written exposure 
control plans, such as the CPWR-Center for Construction Research and 
Training (CPWR) tool, available free of charge, on the silica-safe.org 
Web site (Document ID 2329, p. 5; 4204, p. 61; 4223, pp. 80-81; 4073, 
Attachment 5a and 5b). AFL-CIO and BCTD also pointed to guidance 
products and model exposure control plans from the Canadian Province of 
British Columbia as additional resources for assisting users in 
developing written exposure control plans (Document ID 4204, p. 61; 
4223, p. 81; 4072, Attachment 14, 19, 20). Industry associations are 
another resource to help employers prepare written plans. For example, 
Anthony Zimbelman, general contractor, representing NAHB, testified 
that his industry association teaches courses and helps businesses 
develop safety plans (Document ID 3587, Tr. 3559-3560).
    OSHA finds the evidence on the benefits of a written exposure 
control plan--as distinct from the proposed written access control 
plan--convincing and has concluded that a requirement for a written 
exposure control plan is needed for both the standard for general 
industry/maritime and the standard for construction because the plan 
will improve employee protections. OSHA agrees with commenters who 
stated that a written plan should not be limited to scenarios where the 
PEL is exceeded. Therefore, OSHA concludes that it is appropriate for 
the rule to require a written exposure control plan, instead of a 
written access control plan that would only apply to restricting access 
to areas where exposures to respirable crystalline silica exceed the 
PEL. Requiring a written exposure control plan for all employers 
covered by the rule is more protective than the ASTM approach of only 
requiring written exposure control plans for persistent overexposures. 
Even if exposures are below the PEL due to the use of engineering 
controls or work practices, a systematic approach for ensuring proper 
function of engineering controls and effective work practices is 
crucial for ensuring that those controls and practices remain 
effective. Thus, OSHA finds that a written exposure control plan is 
integral to preventing overexposures from occurring.
    OSHA agrees with NISA that requiring employers to articulate 
conditions resulting in exposure and how those exposures will be 
controlled will help to ensure that they have a complete understanding 
of the controls needed to comply with the rule. OSHA expects a written 
exposure control plan will be instrumental in ensuring that employers 
comprehensively and consistently protect their employees. Even in cases 
where employees are well trained, the written plan can help to ensure 
that controls are consistently used and become part of employees' 
routine skill sets. Employers could opt to use the plans to ensure that 
maintenance checks are routinely performed and optimal conditions are 
maintained. In addition, OSHA concludes the written plans are a useful 
method for communicating protections to employees.
    Requiring a written plan maintains consistency with the majority of 
OSHA substance-specific standards for general industry and 
construction, such as lead (29 CFR 1910.1025 and 1926.62) and cadmium 
(29 CFR 1910.1027 and 1926.1127), which require written compliance 
plans. A requirement for a written exposure control plan is also 
consistent with Canadian standards. In addition, it is generally 
consistent with industry practices, as evidence in the record indicates 
that some employers in general industry and construction are already 
developing and using written plans. OSHA concludes that even for small 
businesses, preparing a written exposure control plan based on 
identifying and controlling respirable crystalline silica hazards will 
not be unduly burdensome, because of the widespread availability of 
tools and guidance from groups such as CPWR and the Canadian 
government. In addition, OSHA anticipates that industry associations 
will provide guidance on developing written exposure control plans for 
respirable crystalline silica.
    Contrary to the concerns indicated by comments from representatives 
from the construction industry, OSHA does not intend or expect that 
employers will need to develop a new written plan for each job or 
worksite. Many of the same tasks will be conducted using the same 
equipment and materials at various worksites. For example, a stationary 
masonry saw used outdoors to cut concrete will perform similarly in any 
outdoor setting. Most construction employers are expected to use the 
specified exposure control methods in Table 1 of paragraph (c), which 
will help them identify tasks and controls to be included in the 
written exposure control plan. Table 1 does not usually specify 
different controls for different types of crystalline silica-containing 
materials, thus supporting the conclusion that a new plan does not need 
to be continually developed. Table 1 does list some conditions, such as 
time performing tasks or use of equipment in enclosed areas, that would 
require respirator use in addition to the specified controls; those 
different scenarios can be indicated in the written exposure control 
plan, as applicable. Therefore, the written exposure control plan does 
not have to be limited by materials, tasks, and conditions for a 
particular job site and can include all materials, tasks, and 
conditions typically encountered. In many cases there will be no need 
to modify the written plan just because the location has changed. 
However, the plan must address all materials, tasks, and conditions 
that are relevant to the work performed by a particular company. OSHA 
is including in the docket a sample written exposure control plan for a 
bricklaying company for reference.
    OSHA concludes that it is appropriate to include a requirement for 
a written exposure control plan in the respirable crystalline silica 
standards for general industry/maritime and construction. Therefore 
paragraph (f)(2)(i) of the standard for general industry and maritime 
(paragraph (g)(1) of the standard for construction) requires the 
employer to establish and implement a written exposure control plan 
that contains at least the elements specified in paragraphs 
(f)(2)(i)(A)-(C) of the standard for general industry and maritime 
(paragraph (g)(1)(i)-(iv) of the standard for construction). This 
provision not only requires that a written exposure control plan be 
established but also implemented. OSHA does not consider it sufficient 
to develop a plan and have a copy of it on a shelf. It must be followed 
in the day-to-day performance of tasks identified.
    OSHA considered existing written exposure control plans, such as 
the ASTM plans, and commenter suggestions to determine what should be 
included in a written exposure control plan. Section 4.2.5 of ASTM 
standard E 2625-09 concerning construction and demolition provides:

    In areas where overexposures are persistent, a written exposure 
control plan shall be established to implement engineering, work 
practice, and administrative controls to reduce silica exposures to 
below the PEL, or other elected limit, whichever is lower, to the 
extent feasible. Conduct a root cause analysis for all exposures in 
excess of the PEL that cannot be accounted for. Root cause analysis

[[Page 16801]]

involves investigating cause(s) for the excessive exposure, 
providing remedies, and conducting follow-up sampling to document 
that exposures are below the PEL (Document ID 1504, p. 2).

    The exposure control plan described in section 4.2.6 of ASTM 
standard E 1132-06 is substantively consistent with the approach 
described by section 4.2.5 of ASTM standard E 2625-09 (Document ID 
1466, p. 2; 1504, p. 2).
    Several stakeholders commented on what should be included in 
provisions for a written exposure control plan. ASSE described an 
approach similar to that in the ASTM standards, and AFS preferred the 
ASTM approach during enforcement actions (Document ID 2339, p. 8; 2379, 
Appendix 1, pp. 61-62).
    NIOSH stated that the exposure control plan could be based on 
OSHA's Job Hazard Analysis approach (Document ID 2177, Attachment B, p. 
16; OSHA document 3071, Revised 2002). The OSHA job hazard analysis 
form calls for descriptions of tasks, hazards, hazard controls, and 
rationale and comments (OSHA document 3071, Revised 2002, Appendix 3). 
Similarly, NISA recommended that written exposure control programs 
convey an understanding of work processes and their appropriate 
controls for managing exposures (Document ID 4208, p. 21).
    Some labor unions, such as AFL-CIO and BCTD, recommended more 
extensive requirements for a written exposure control or compliance 
program that included identification of exposures and controls, in 
addition to exposure assessment methods or results, and descriptions of 
the respiratory protection, medical surveillance, and training programs 
(Document ID 2371, Attachment 1, pp. 16-17; 4204, p. 62; 4223, p. 82).
    Commenters such as Public Citizen, USW, UAW, and BCTD all agreed 
that the value of a written exposure control plan is that it allows for 
consistent identification and control of respirable crystalline silica 
hazards (Document ID 2249, p. 2; 2336, pp. 8-9; 2282, Attachment 3, p. 
17; 3581, Tr. 1569-1571; 4204, p. 60). OSHA affirms that the purpose of 
the written exposure control plan is the consistent identification and 
control of respirable crystalline silica hazards, and it is basing the 
requirements for a written exposure control plan on that purpose.
    As discussed more fully below, the written exposure control plan 
required under this rule for respirable crystalline silica is similar 
to the ASTM standards in most, but not all, respects. The major 
difference between the written plans in the ASTM standards and in this 
rule is that written exposure control plans in this rule are not 
limited to overexposure scenarios.
    OSHA thus considered the ASTM standards and commenter suggestions 
to develop requirements for a written exposure control plan. The Agency 
also considered which aspects of the proposed written access control 
plan should be retained or modified. Therefore, the requirement for a 
written exposure control plan evolved from comments on OSHA's proposed 
written access control plan and in response to OSHA raising the 
possible inclusion of a written exposure control plan as an issue.
    Requirements for the written exposure control plan. Paragraphs 
(f)(2)(i)(A)-(C) of the standard for general industry and maritime 
(paragraphs (g)(1)(i)-(iv)) of the standard for construction) identify 
the elements to be addressed in a written exposure control plan. 
Requirements for the written exposure control plan are performance-
based to allow employers to tailor written exposure control plans to 
their particular worksites. The following discussion describes the 
minimum requirements for the written exposure control plan and the 
evidence that supports those requirements. It also recommends general 
information to include for each section of the plan.
    Paragraph (f)(2)(i)(A) of the standard for general industry and 
maritime (paragraph (g)(1)(i)) of the standard for construction) 
requires a description of tasks involving exposures to respirable 
crystalline silica. The proposed written access control plan called for 
identification of areas where respirable crystalline silica exposure 
may exceed the PEL. Communication Workers of America (CWA), Public 
Citizen, USW, AFL-CIO, NISA, and BCTD recommended that the written 
exposure control plan describe tasks, operations, or work processes 
that result in exposures to respirable crystalline silica (Document ID 
2240, p. 2; 2249, p. 3; 2336, p. 9; 4204, p. 62; 4208, p. 21; 4223, p. 
82). A description of tasks involving exposures to respirable 
crystalline silica is consistent with the first step of the root cause 
analysis in the ASTM exposure control plans, which involves 
investigating sources of overexposures (Document ID 1466, p. 2; 1504, 
p. 2). It is also consistent with the identification of tasks and 
hazards in the OSHA Job Hazard Analysis approach that is recommended by 
NIOSH as a model for a respirable crystalline silica written exposure 
control plan (Document ID 2177, Attachment B, p. 16; OSHA Document 
3071, Revised 2002, Appendix 3).
    Paragraph (f)(2)(i)(A) of the standard for general industry and 
maritime (paragraph (g)(1)(i) of the standard for construction) 
reflects OSHA's agreement with commenters that it is important for 
employers to consistently identify tasks resulting in exposure to 
ensure that appropriate employee protections are applied when needed. 
The identification of tasks with potential respirable crystalline 
silica exposure is no longer limited to exposures above the PEL, as it 
was in the proposed written access control plan. This is more 
protective because it identifies all tasks that could contribute to 
employee exposures, thereby furthering the purpose of the rule.
    In preparing this section of the written plan, employers must list 
all tasks that employees perform that could expose them to respirable 
crystalline silica dust. This section of the written plan could include 
a description of factors that affect exposures, such as types of 
silica-containing materials handled in those tasks (e.g., concrete, 
tile). It could also describe factors such as weather (e.g., wind, 
humidity) and soil compositions (e.g., clay versus rock) (Document ID 
3583, Tr. 2350-2352, 2356-2360; 4234, Part 2, pp. 37-38). Another 
factor that could affect exposure and protective requirements and thus 
could be described in the written plan is the location of the task, for 
instance, whether the task is performed in an enclosed space (Document 
ID 2177, Attachment B, pp. 16-17). For example, the Table 1 entry for 
walk-behind saws with integrated water delivery systems indicates that 
a respirator is only required when the equipment is used indoors or in 
an enclosed area.
    Paragraph (f)(2)(i)(B) of the standard for general industry and 
maritime (paragraph (g)(1)(ii) of the standard for construction) 
requires a description of engineering controls, work practices, and 
respiratory protection used to limit employee exposure to respirable 
crystalline silica for each task. CWA, Public Citizen, USW, AFL-CIO, 
NISA, and BCTD requested that the written plan describe controls for 
managing exposures. Engineering and work practice controls were 
specifically mentioned by Public Citizen, USW, AFL-CIO, and BCTD 
(Document ID 2240, p. 2; 2249, pp. 3-4; 2336, p. 9; 4204, p. 62; 4208, 
p. 21; 4223, p. 82). AFL-CIO further recommended that the written plan 
describe jobs where respiratory protection is required (Document ID 
4204, p. 62). BCTD also requested that the written plan describe 
procedures for implementing the controls and for determining if the

[[Page 16802]]

controls are being used and maintained correctly (Document ID 4223, p. 
82). NIOSH stated that a written exposure control plan can be a simple 
mechanism for ensuring that maintenance checks are conducted and Table 
1 conditions are maintained (Document ID 2177, Attachment B, pp. 16-
17).
    Paragraph (f)(2)(i)(B) of the standard for general industry and 
maritime (paragraph (g)(1)(ii) of the standard for construction) 
reflects OSHA's agreement that the written exposure control plan must 
address controls, work practices, and respiratory protection used to 
manage exposures for each task identified in paragraph (f)(2)(i)(A) of 
the standard for general industry and maritime (paragraph (g)(1)(i) of 
the standard for construction). The purpose of this requirement is to 
ensure that exposures to respirable crystalline silica hazards are 
consistently controlled. Therefore, written exposure control plans must 
include information such as types of controls used (e.g., dust 
collector with manufacturer's recommended air flow and a filter with 99 
percent efficiency), effective work practices (e.g., positioning local 
exhaust over the exposure source), and if required, appropriate 
respiratory protection (e.g., a respirator with an assigned protection 
factor (APF) of 10) for each task. The requirement is consistent with 
the exposure control plans in the ASTM standards that address 
implementation of engineering controls and work practices to reduce 
respirable crystalline silica exposures (Document ID 1466, p. 2; 1504, 
p. 2). It is also consistent with OSHA's Job Hazard Analysis approach, 
which is recommended by NIOSH as a model for the exposure control plan 
and calls for a description of controls (Document ID 2177, Attachment 
B, p. 16; OSHA document 3071, Revised 2002, Appendix 1 and 3).
    OSHA also agrees with NIOSH and BCTD about the necessity of 
addressing the proper implementation and maintenance of controls for 
each task. This is reflected in paragraph (c) of the standard for 
construction, in the Table 1 requirements to operate or maintain tools 
according to manufacturers' instructions. Proper implementation and 
maintenance of controls is also necessary to meet the PEL under 
paragraph (c) of the standard for general industry and maritime and 
paragraph (d)(1) of the standard for construction for construction 
employers who choose or are required to follow the alternative exposure 
control methods. Therefore, to help ensure compliance with the rule, 
the employer, in this section of the written exposure control plan, 
could indicate signs that controls may not be working effectively 
(e.g., dust is visible, no water is delivered to the blade). The plan 
could also include a description of procedures the employer uses for 
verifying that controls are functioning effectively (e.g., pressure 
checks on local exhaust ventilation) and schedules for conducting 
maintenance checks.
    OSHA finds the written exposure control plan especially important 
for construction employers who use the specified exposure control 
methods in Table 1 of paragraph (c). For them, the description of 
engineering controls, work practices, and respiratory protection is 
especially necessary to ensure adequate protection of employees and the 
use of controls according to the manufacturer's instructions, since 
employers are not required to conduct exposure assessments to verify 
that controls are working properly. In cases where the employer owns a 
particular type of equipment and it is repeatedly used at different job 
sites, describing the manufacturer's instructions for operating the 
dust controls in a written exposure control plan will demonstrate that 
the employer has a complete understanding of and is applying those 
specifications needed to control dust emissions. Describing those 
specifications in the written exposure control plans will also serve as 
a convenient reference for employees.
    As an example, in completing this section of the written plan, an 
employer whose employees use a Stihl[supreg] Model TS 410 saw to cut 
concrete could consult the user's manual to list or summarize those 
instructions in his or her written exposure control plan. Based on the 
user's manual, this section of the plan could indicate that (1) before 
using a Stihl[supreg] Model TS 410 saw for cutting concrete, the 
employee must examine the diamond cutting wheel for signs of excessive 
wear, damage, or ``built-up edges'' (i.e., a pale, grey deposit on the 
top of the diamond segments that clogs and blunts them) and (2) while 
cutting, the employee must use a water flow rate no less than 0.6 
liters (20 fluid ounces) per minute, stop and rinse the screen on the 
water connection if no or too little water is delivered while cutting, 
and not cut into the ballast layer of road surfaces to avoid excessive 
wear on the cutting wheel (Document ID 3998, Attachment 12a, pp. 9, 21-
23). The specified exposure control methods in Table 1 indicate that 
the employee must wear a respirator with an APF of 10 when using this 
saw outdoors for more than 4 hours a day, and this type of information 
must be included in this section, if applicable.
    Paragraph (f)(2)(i)(C) of the standard for general industry and 
maritime (paragraph (g)(1)(iii) of the standard for construction) 
requires a description of the housekeeping measures used to limit 
employee exposure to respirable crystalline silica. BCTD requested that 
the exposure control plan describe housekeeping methods (Document ID 
2371, Attachment 1, pp. 16-17). Similarly, CWA and USW recommended that 
the written plan describe procedures for preventing the migration of 
silica, and USW further noted that the plan should address keeping 
surfaces visibly clean (Document ID 2240, p. 2; 2336, p. 9). USW also 
requested that the written exposure control plan describe procedures 
for removing, laundering, storing, cleaning, repairing, or disposing of 
protective clothing and equipment (Document ID 2336, p. 9).
    Paragraph (f)(2)(i)(C) of the standard for general industry and 
maritime (paragraph (g)(1)(iii)) of the standard for construction) 
reflects OSHA's agreement that housekeeping needs to be addressed in 
the written exposure control plan because some cleaning methods can 
contribute to employee exposure to respirable crystalline silica. OSHA 
intends this requirement to help ensure that employers identify and 
implement appropriate cleaning methods so that employees are protected 
from respirable crystalline silica dust that can become airborne while 
performing housekeeping activities. Ensuring safe housekeeping methods 
helps to consistently control exposures and hazards related to 
respirable crystalline silica. Housekeeping is another type of work 
practice to be used to limit employee exposures, and thus, it is 
consistent with the written exposure control plans in the ASTM 
standards, which call for implementing work practices to decrease 
exposures (Document ID 1466, p. 2; 1504, p. 2). It is also consistent 
with OSHA's Job Hazard Analysis approach, which is recommended by NIOSH 
as a model for the exposure control plan and calls for a description of 
controls (Document ID 2177, Attachment B, pp. 16-17; OSHA document 
3071, Revised 2002, Appendix 1 and 3).
    OSHA concludes that requiring the written exposure control plan to 
include a description of housekeeping methods is important because 
acceptable housekeeping methods can vary among different companies. As 
described more fully in the summary and explanation of Housekeeping, 
certain housekeeping practices, such as wet sweeping, are infeasible in 
some work scenarios.

[[Page 16803]]

Therefore, OSHA modified proposed prohibitions on cleaning activities, 
such as dry sweeping or compressed air, to indicate that those 
housekeeping methods can be used if there are no other feasible 
methods. However, to comply with the rule, employers must ensure that 
wet sweeping, HEPA-filtered vacuuming, or other appropriate cleaning 
methods are used wherever feasible, if dry sweeping or dry brushing 
could contribute to employee exposure to respirable crystalline silica. 
It is therefore important for the employer to specify in the written 
exposure control plan the housekeeping practices the employer uses to 
limit employee exposures and any special protections that are needed 
when a particular housekeeping method is used.
    To ensure that cleaning methods used comply with paragraph (h) of 
the standard for general industry and maritime (paragraph (f) of the 
standard for construction), this section of the written plan could 
include a description of acceptable and prohibited cleaning methods 
used by the employer to minimize generation of airborne dust and 
special instructions regarding cleaning methods (e.g., using local 
exhaust ventilation if compressed air must be used). Hygiene-related 
subjects, such as not using compressed air to clean clothing, could 
also be addressed in this section of the written exposure control plan.
    Paragraph (g)(1)(iv) of the standard for construction requires a 
description of the procedures used to restrict access to work areas, 
when necessary, to limit the number of employees exposed to respirable 
crystalline silica and the levels to which they are exposed, including 
exposures generated by other employers or sole proprietors. No such 
requirement is included in the written exposure control plan provision 
for general industry and maritime. The reasons for the differing 
requirements in the two standards are discussed below.
    The proposed written access control plans for general industry and 
maritime and construction called for procedures for notifying employees 
about the presence and location of areas where respirable crystalline 
silica concentrations are or can be reasonably expected to exceed the 
PEL and for demarcating those areas from the workplace if needed. Also 
included in the proposed access control plan were provisions for 
limiting access to areas where respirable crystalline silica exposures 
may exceed the PEL, in order to minimize the numbers of employees 
exposed and employee exposure levels.
    AFL-CIO and BCTD recommended that written plans describe procedures 
that employers will use to limit exposure to employees who are not 
performing respirable crystalline silica-related tasks (Document ID 
4204, p. 63; 4223, p. 82). Similarly, BAC stated that the written plan 
should contain provisions for a regulated area (Document ID 2329, p. 
5). USW requested the written plan address labeling of areas with 
potential respirable crystalline silica exposure (Document ID 2336, p. 
14).
    Paragraph (g)(1)(iv) of the standard for construction reflects 
OSHA's agreement that written exposure control plans must address 
limiting exposure to construction employees who are not engaged in 
respirable crystalline-silica-related tasks. However, as explained in 
the summary and explanation of Regulated Areas, regulated areas are not 
required in the standard for construction because most employers are 
expected to rely on the specified exposure control methods in Table 1 
of paragraph (c) and, therefore, will not have air monitoring data to 
estimate boundaries of the regulated area. In the summary and 
explanation of Regulated Areas, OSHA also acknowledges the 
impracticality of demarcating regulated areas in many construction 
scenarios. Nonetheless, it remains crucial that access to high-exposure 
areas and employee exposure levels be limited at construction 
worksites. A written description of the employer's plan for limiting 
access is another tool the employer has that helps to consistently 
control hazards.
    The exposure control plans in the ASTM standards do not 
specifically call for procedures used to restrict access. However, they 
do call for a description of administrative controls used to reduce 
exposures (Document ID 1466, p. 2; 1504, p. 2). An example of an 
administrative control that can be used to minimize the number of 
employees exposed to respirable crystalline silica is scheduling high-
exposure tasks when others will not be in the area (Document ID 3583, 
Tr. 2385-2386). For example, Anthony Zimbelman stated that when granite 
countertops are being installed, silica dust may be generated when 
drilling holes for plumbing fixtures or grinding to make adjustments, 
but the installers are usually the only employees at the job site at 
that time (Document ID 3521, pp. 6-7). CISC stated that in lieu of 
developing a written access control plan, employers could instruct 
employees to stay out of areas where dust is generated or, if employees 
have to be in those areas, to avoid dust clouds (Document ID 2319, pp. 
91-92). OSHA considers the CISC recommendation to be an additional 
example of administrative controls for limiting access or exposures 
that could be addressed in the written exposure control plan. 
Similarly, a written exposure control plan could include guidance 
requiring employees to maintain a safe distance from dust created by 
the use of explosives in demolition and to stay out of the affected 
area until the dust sufficiently dissipates; this would also serve as 
an acceptable administrative control. Therefore, a requirement for the 
written plan in the construction standard to address minimizing the 
number of employees exposed and their exposure levels is consistent 
with the exposure control plans in the ASTM standards.
    OSHA concludes that the written exposure control plan for the 
construction standard must address restricting access of those 
employees who are not engaged in tasks that generate respirable 
crystalline silica (i.e., bystanders). Therefore, as noted above, 
paragraph (g)(1)(iv) of the standard for construction requires a 
description of the procedures used to restrict access to work areas, 
when necessary, to limit the number of employees exposed and their 
exposure levels, including exposures generated by other employers or 
sole proprietors (i.e., self-employed individuals). Restricting access 
is necessary where respirator use is required under Table 1 or an 
exposure assessment reveals that exposures are in excess of the PEL. 
The competent person, who is designated by the employer to implement 
the written exposure control plan under paragraph (g)(4) of the 
standard for construction, could further identify situations where 
limiting access is necessary. For example, limiting access may be 
necessary when an employer or sole proprietor exposes another company's 
employees to respirable crystalline silica levels that could reasonably 
be considered excessive (e.g., above the PEL).
    Such a situation might occur when an employee engaged in a Table 1 
task with fully and properly implemented controls is exposed to clearly 
visible dust emissions by an employee or sole proprietor who is 
performing a task not listed on Table 1, is not fully and properly 
implementing Table 1 controls, or is performing a Table 1 task 
requiring a higher level of respiratory protection. In that case, the 
competent person would assess the situation to determine if it presents 
a reasonably anticipated hazard, and if it does, take immediate and 
effective steps to protect employees by implementing the procedures 
described in the written exposure control plan. Actions by the 
competent

[[Page 16804]]

person could include reminding employees to stay out of the areas where 
respirable crystalline silica is being generated or repositioning 
employees so that they will not be exposed to respirable crystalline 
silica.
    This approach is consistent with current industry practices. For 
example, Anthony Zimbelman testified that in his experience, 
implementing a safety plan was sufficient to protect employees in 
situations where subcontractors that are not required to comply with 
the Occupational Safety and Health (OSH) Act are working alongside 
employees. Mr. Zimbelman further testified that in the home building 
industry, this situation does not happen often and contractors would 
stop working with a subcontractor who does not comply with OSHA 
standards (Document ID 3587, Tr. 3547-3549). OSHA expects that 
excessive exposures created by sole proprietors not covered by the 
respirable crystalline silica rule will be an infrequent occurrence 
because, as CISC indicated in its post-hearing brief, employers and 
general contractors will likely demand that everyone on the site follow 
regulatory requirements (Document ID 4217, Appendix B, p. 16). OSHA 
thus expects that the employers or their competent persons will work 
with general contractors of construction sites to avoid high exposures 
of employees working alongside others generating respirable crystalline 
silica. For example, the competent person could ask the general 
contractor to schedule high-exposure tasks when employees will not be 
in the area.
    OSHA is not retaining the proposed requirement in the written 
access control plan that the employer describe how employees will be 
notified about respirable crystalline silica exposures and how areas 
will be demarcated. The requirements of the written exposure control 
plan are more performance-oriented to permit each employer to address 
unique scenarios of worksites. Demarcation (i.e., direct access 
control), notifying or briefing employees, and scheduling high-exposure 
tasks when others are not around, are likely to be the most common 
methods of restricting access. Demarcating areas is not required 
because, as noted above, it is not applicable to many construction 
scenarios. However, if it is possible to demarcate areas, such as by 
posting a warning sign, and that is the employer's chosen method for 
limiting access or exposures, it must be described in this section of 
the written exposure control plan. If notifying or briefing employees 
is the method chosen to limit access or exposures, the procedures for 
doing that must be described under this section of the written exposure 
control plan.
    As noted above, the standard for general industry and maritime does 
not require the written exposure control plan to address how access to 
high-exposure areas or employee exposures will be limited. As described 
in more detail in the summary and explanation of Regulated Areas, OSHA 
concludes that establishing regulated areas is reasonable and generally 
feasible in general industry and maritime workplaces. Therefore, the 
standard for general industry and maritime clearly specifies 
establishment of regulated areas that are demarcated and have warning 
signs posted at the entrances to those areas (paragraph (e)(1) and 
(2)(i) and (ii)). With the procedure clearly laid out in the standard, 
there is no reason to address it in the written exposure control plan. 
However, employers can address more than the minimum requirements for a 
written exposure control plan, and general industry and maritime 
employers always have the option of describing methods for limiting 
access in their written exposure control plan.
    The proposed written access control plan called for a description 
of the methods that employers at multi-employer sites would use to 
notify other employers about the presence and location of areas where 
respirable crystalline silica may exceed the PEL and any precautionary 
methods needed to protect employees. AFL-CIO, BAC, and BCTD commented 
that written plans should provide for a method of communication at 
multi-employer sites (Document ID 4204, pp. 62-63; 4219, pp. 25-27; 
4223, pp. 83-84). BCTD stated that a requirement for a written plan to 
describe methods of communication at multi-employer sites was not 
sufficient and requested that employers also be required to give their 
written plan to a general contractor or other ``controlling employer'' 
at a multi-employer construction site. The controlling employer would 
be required to share that information with other employers or use the 
plan to coordinate activities to reduce exposures to employees 
(Document ID 4223, pp. 118-123). AFL-CIO and BAC endorsed BCTD's 
approach and/or recommended a similar method for using the written 
exposure control plan to communicate at multi-employer worksites 
(Document ID 4204, p. 63; 4219, pp. 25-27). Similarly, ASSE stated that 
employers who generate respirable crystalline silica exposures at 
multi-employer sites should inform the general contractor or host 
employer about the need for access control and work cooperatively with 
the general contractor or host employer to ensure compliance and notify 
other employers at the site (Document ID 2339, p. 8).
    In contrast, NSSGA commented that the HCS already requires 
employers to establish methods for communicating hazards to employees 
of other employers (Document ID 2327, Attachment 1, p. 11). NAHB 
commented that ``. . . the imposition of multi-employer burdens in the 
proposed rule is inconsistent with the clear wording of Sec.  
1910.12(a) requiring a construction employer to protect `each of his 
employees engaged in construction work' (Emphasis added)'' (Document ID 
2296, pp. 27-28). OSHA disagrees that a requirement to communicate the 
presence of crystalline silica to other employers contradicts the 29 
CFR 1910.12(a) requirement that employers protect their employees. 
Communication among employers about areas where respirable crystalline 
silica exposures may exceed the PEL will provide each employer with the 
information needed to protect its own employees.
    OSHA nonetheless concludes that the written exposure control plan 
need not specify communication methods at multi-employer sites, or 
require that employers share their written exposure control plans at 
multi-employer sites. Communication at multi-employer worksites is 
already addressed in the HCS. As part of the written hazard 
communication program required under the HCS, employers who use 
hazardous chemicals in such a way that employees of other employers may 
be exposed must include specific information in the written hazard 
communication program. This includes methods the employer will use to 
inform the other employers of any precautionary measures that need to 
be taken to protect employees (29 CFR 1910.1200(e)(2)(ii)). Because the 
provisions for a written hazard communication program under the HCS 
already require employers to share relevant information on hazards and 
protective measures with other employers in multi-employer workplaces, 
OSHA does not find it necessary to restate a requirement for sharing of 
information between employers in the respirable crystalline silica 
rule. However, as discussed above, written exposure control plans are 
useful for communicating information, and employers may decide that 
they are a convenient way for sharing information with other employers 
at multi-employer workplaces.
    Additional provisions that were part of the proposed access control 
plan but

[[Page 16805]]

are not required for the written exposure control plan are procedures 
for providing employees and their designated representatives an 
appropriate respirator, protective clothing, or a means for cleaning 
clothing when entering areas where exposures exceed the PEL or where 
clothing could become grossly contaminated with finely divided 
material. OSHA is not requiring the written exposure control plan to 
address this subject because procedures related to providing employees 
with appropriate respirators, such as selection of respirators, medical 
evaluations, and training, must already be described in a written 
respiratory protection program (29 CFR 1910.134(c)(1)). In most cases, 
the designated representative, who requires entry into a regulated area 
or an area with restricted access for purposes such as observing air 
monitoring, is likely to have access to appropriate respiratory 
protection and be medically cleared to wear it (see summary and 
explanation of Exposure Assessment). As OSHA determined in the summary 
and explanation of Exposure Assessment, requirements of the written 
respiratory protection program related to providing an appropriate 
respirator would also apply to the designated representative in the 
very rare case where the representative does not have a respirator. 
Protective clothing is not addressed in the written exposure control 
plan because it is not required by the rule. Recommendations concerning 
cleaning of clothing, such as not using compressed air, could be 
addressed as part of housekeeping measures or work practice controls.
    Some commenters requested that written plans address additional 
topics and requirements. For example, Public Citizen, BCTD, and AFL-
CIO, requested that the written exposure control plan describe exposure 
assessment methods or programs (e.g., air monitoring or objective data) 
and results (Document ID 2249, pp. 3-4; 2371, Attachment 1, p. 16; 
4204, p. 62; 4223, p. 82). Public Citizen indicated that this should 
include detailed descriptions of analytical methods and air sampling 
protocols or objective exposure assessment methods, and BCTD stated 
that employers using Table 1 could indicate the portion of Table 1 upon 
which they are relying (Document ID 2249, pp. 3-4; 4223, p. 82). BCTD 
and AFL-CIO recommended that the written plan address respiratory 
protection, medical surveillance, and training programs, including 
documentation that employees have received respiratory fit testing, 
medical evaluations or examinations, and training (Document ID 4204, p. 
62; 4223, p. 82). Public Citizen requested that the plan be prepared by 
a technically qualified person if the employer lacks the expertise to 
prepare and implement the plan (Document ID 2249, p. 4). ASSE preferred 
that the plans be developed by a certified safety professional or 
certified industrial hygienist (CIH) (Document ID 2339, p. 8). NAHB 
expressed concern about costs if small companies had to hire safety 
consultants or industrial hygienists to develop the plan (Document ID 
2296, p. 41).
    OSHA disagrees with commenters that the written exposure control 
plan needs to address these topics. The major purpose of a written 
exposure control plan is to ensure that respirable crystalline silica 
hazards are consistently identified and controlled. OSHA concludes that 
this purpose is best served if the written plan is limited to 
information useful for the employer or the employer's designated 
representative who will conduct inspections on job sites to ensure that 
employees are adequately and consistently protected. Requiring a 
written exposure control plan to contain information that is not 
directly relevant to identifying and controlling hazards at job sites 
would needlessly increase the burdens to employers preparing the 
written plans and could make the plans cumbersome for them to use on 
job sites. In addition, OSHA does not see the need for including a 
description of the respiratory protection program because employers are 
already required to develop a written respiratory protection program 
under the respiratory protection standard (29 CFR 1910.134(c)). 
Recordkeeping requirements are clearly specified for fit testing and 
medical evaluations in the respiratory protection standard (29 CFR 
1910.134) and for medical examinations and exposure assessments in this 
rule. The respirable crystalline silica rule does not require employers 
to keep training records. As explained in more detail in the summary 
and explanation of Recordkeeping, the rule does not require training 
records because employers must instead ensure that employees 
demonstrate knowledge and understanding of training subjects and in 
addition, such a requirement would increase paperwork burdens for 
employers and would not be consistent with the HCS and most OSHA 
standards.
    Therefore, OSHA is neither requiring nor precluding employers to 
include in written exposure control plans descriptions of exposure 
assessment methods and results or information on respiratory 
protection, medical surveillance, and training programs. Requiring 
information, such as highly technical details on analytical methods, 
would increase the likelihood that small employers would need to hire a 
safety and health professional to develop the plans, thus increasing 
the costs and burdens to those employers. Although OSHA encourages 
companies to seek professional assistance when needed to develop the 
plans, requiring a plan that is so complex that many employers would 
not develop it themselves defeats the advantage of employers gaining an 
increased understanding of the rule by articulating its requirements. 
The additional information may be useful as part of a compliance plan, 
and employers have the option to develop such a plan if they find it 
helpful.
    Paragraph (f)(2)(ii) of the standard for general industry and 
maritime (paragraph (g)(2) of the standard for construction) requires 
the employer to review and evaluate the effectiveness of the written 
exposure control plan at least annually and update it as necessary. A 
similar requirement was included in the proposed written access control 
plan. Public Citizen requested revisions of written exposure control 
plans as needed, including after annual review of exposure assessment 
methods (Document ID 2249, p. 4). OSHA agrees with Public Citizen that 
the written exposure control plan needs to be periodically reviewed and 
updated as needed because work conditions can change (e.g., the 
employer purchases a new type of equipment). As discussed above, a 
written exposure control plan will not likely need to be updated often 
because employees tend to use the same equipment to perform the same 
tasks at many locations. However, a yearly review is needed to ensure 
that all current scenarios are captured in the plan.
    Paragraph (f)(2)(iii) of the standard for general industry and 
maritime (paragraph (g)(3) of the standard for construction) requires 
that the employer make the written exposure control plan readily 
available for examination and copying, upon request, to each employee 
covered by this section, his or her designated representative, the 
Assistant Secretary (i.e., OSHA), or the Director (i.e., NIOSH). A 
similar requirement was included in the proposed written access control 
plan. Public Citizen, USW, BCTD, and AFL-CIO requested a requirement to 
make written exposure control plans available upon request by employees 
or their representatives (Document ID 2249, p. 4;

[[Page 16806]]

2336, p. 9; 2371, Attachment 1, p. 17; 4204, p. 63). NIOSH, Public 
Citizen, and BAC also stated that written exposure control plans are a 
useful way to communicate protections to employees (Document ID 2177, 
Attachment B, pp. 16-17; 2249, p. 3; 2329, p. 5). OSHA agrees with 
commenters that a written exposure control plan is an effective method 
for communicating protections to employees and their designated 
representatives. Making the written plan readily available to employees 
and their designated representatives upon request empowers and protects 
employees by giving them and their representatives the information to 
question employers if controls are not fully and properly implemented 
or maintained. Similarly, making written exposure control plans readily 
available to OSHA or NIOSH allows them to verify effectiveness of 
employee protections.
    BCTD also requested that the rule require employers to address in 
their written plans how temporary workers will be protected and that 
the rule require staffing agencies and employers who use temporary 
staff to share their written exposure control plans (Document ID 4223, 
pp. 83-84). OSHA disagrees with BCTD that the rule needs to include a 
requirement for host employers and temporary staffing agencies to share 
their written exposure control plans with each other. However, OSHA 
agrees with the importance of ensuring that temporary workers receive 
the protections they are entitled to under the OSH Act. As BCTD noted 
in its comments, OSHA addresses the issue of temporary employee 
protections in its July 15, 2014, memorandum titled Policy Background 
on the Temporary Worker Initiative (Document ID 4223, p. 84). The 
policy memorandum indicates that both the host and staffing agency are 
responsible for the health and safety of temporary employees and 
encourages compliance officers to review written contracts between the 
staffing agency and host employer to determine if they have fully 
addressed employee health and safety. For example, the policy 
memorandum indicates that host employers are well suited for assuming 
responsibility for compliance related to workplace hazards, while 
staffing agencies may be best positioned to provide medical 
surveillance. The memorandum also states that although the host 
employer has the primary responsibility for assessing hazards and 
complying with occupational safety and health rules in his or her 
workplace, staffing agencies must also ensure that they are not sending 
employees to workplaces where the employees would be inadequately 
protected from or trained about hazards. A temporary staffing agency 
could review a host employer's written exposure control plan to verify 
that the employer has identified hazards and is implementing the 
appropriate controls. Staffing agencies and host employers would have 
the option to supplement their written contract with a written exposure 
control plan if that is useful for them. OSHA is not requiring that 
host employers and staffing agencies share written exposure control 
plans for respirable crystalline silica because sharing information is 
an issue that affects all OSHA safety and health regulations and is 
therefore most efficiently addressed through general policy statements.
    Competent Person (Construction). In paragraph (b) of the standard 
for construction, OSHA defines competent person as an individual who is 
capable of identifying existing and foreseeable respirable crystalline 
silica hazards in the workplace and who has authorization to take 
prompt corrective measures to eliminate or minimize them. The 
definition also specifies that the competent person have the knowledge 
and ability necessary to fulfill the responsibilities set forth in 
paragraph (g). In paragraph (g)(4) of the standard for construction, 
the employer is required to designate a competent person to make 
frequent and regular inspections of job sites, materials, and equipment 
to implement the written exposure control plan.
    OSHA included a competent person requirement in the draft general 
industry/maritime and construction standards presented for review to 
the Small Business Regulatory Enforcement Fairness Act (SBREFA) review 
panel. In the draft standards submitted for SBREFA review, duties of 
the competent person included evaluating workplace exposures and the 
effectiveness of controls, implementing corrective measures to maintain 
exposures at or below the PEL, establishing and maintaining boundaries 
of regulated areas, and evaluating alternate media for abrasive 
blasting operations. Small entity representatives (SERs) from the 
construction industry who reviewed the SBREFA draft standard found the 
requirements for a competent person hard to understand, reasoning that 
(1) the competent person required a high skill level, (2) a large 
proportion of their employees would need to be trained, and (3) the 
requirements would be costly and difficult to comply with (78 FR at 
56443-56444).
    OSHA's Advisory Committee on Construction Safety and Health 
(ACCSH), made up of representatives of employees, employers, and state 
and federal governments, recommended that the Agency retain a competent 
person requirement in the proposed construction standard because many 
OSHA standards include that requirement, it is an accepted approach for 
construction, many small construction employers do not have full-time 
health and safety staff, it can ensure that designated employees get 
training on hazards and proper use of controls, and it can increase 
confidence that controls and PPE are being used and maintained 
correctly (Document ID 4073, Attachment 14g, pp. 2-3).
    OSHA included a competent person provision in the proposed 
standards, but the only duty that OSHA proposed for the competent 
person was identifying areas where respirable crystalline silica 
concentrations are, or could reasonably be expected to be, in excess of 
the PEL when the employer chose to develop a written access control 
plan in lieu of establishing regulated areas. OSHA proposed this 
limited competent person duty because the Agency thought that 
provisions of the proposed standard, such as requirements for 
engineering controls and work practices to reduce and maintain employee 
exposure to respirable crystalline silica at or below the PEL, would 
effectively communicate the requirements of the rule, without 
involvement of a designated competent person. However, the Agency was 
aware that competent person requirements have been included in other 
health and safety standards and that some parties thought such 
requirements would be useful in the silica rule (78 FR at 56443-56444). 
Therefore, OSHA requested comments regarding the appropriateness of the 
limited competent person requirement, whether a competent person 
provision should be included, and if the proposed duties for a 
competent person should be modified or deleted (78 FR at 56288).
    Many commenters representing labor unions and employee health 
advocate groups disagreed with OSHA proposing to include only a limited 
role for the competent person in construction. Commenters such as 
NIOSH, the Laborers' Health and Safety Fund of North America (LHSFNA), 
ASSE, IUOE, and BCTD supported an expanded competent person role 
because many construction companies are small and cannot afford safety 
or health professionals, but as NIOSH stated, small companies can have 
trained and authorized employees ensure employee protections (Document 
ID 3403, p. 4;

[[Page 16807]]

3589, Tr. 4256-4257; 4201, pp. 2-3; 4025, Attachment 1, p. 2; 4223, pp. 
107-109). OSHA estimates that approximately 93 percent of construction 
companies covered by the respirable crystalline silica standard have 
fewer than 20 employees (see Chapter III of the Final Economic Analysis 
and Final Regulatory Flexibility Analysis). In further explaining why a 
competent person is needed in construction, Dr. Schulte testified:

    The need for expanding the duties of the silica-competent person 
is especially important when employers plan to rely on Table 1 
because it is less likely that an industrial hygienist will visit 
the project to evaluate the job, collect air samples, or check the 
effectiveness of controls. Effectiveness deteriorates when controls 
or personal protective equipment (PPE) are not maintained; this 
performance degradation may not be obvious to workers using the 
devices (Document ID 3403, p. 4).

    The American Industrial Hygiene Association (AIHA), IUOE, and BCTD 
agreed that a competent person is needed to ensure that Table 1 
controls are functioning effectively (Document ID 3578, Tr. 1030; 3583, 
Tr. 2347; 4223, pp. 109-110). BCTD stated:

. . . because the technology for controlling silica exposures 
largely consists of equipment that is attached to or directed at the 
tools the workers use in their silica-generating tasks, the manner 
in which it is deployed and maintained is critical to its success. 
Thus, whether these controls are effective depends on successfully 
combining the engineering controls with work practices: Accurately 
assessing the potential exposures, selecting the proper control for 
the job, using the equipment properly, and making sure the equipment 
is functioning effectively. All of this must be done on an on-going 
basis (Document ID 4223, p. 109).

    Exposure variability in construction is another reason that 
commenters cited in support of expanded competent person duties. For 
example, ASSE commented that varying silica exposures can occur as a 
result of wind pattern and geological changes as contractors move from 
one site to another or to a new area at the same site (Document ID 
4201, p. 2). LHSFNA explained that a competent person can help to 
reduce exposure variability by identifying major sources of variability 
and ensuring that controls are used and maintained effectively 
(Document ID 4207, p. 4). Similarly, NIOSH stated that a competent 
person could reduce exposure variability by recognizing sources of 
variability, such as tasks done in an enclosed area or equipment that 
is not working correctly (Document ID 3579, Tr. 175-176, 194-195). In 
explaining how a competent person could reduce exposure variability, 
Kyle Zimmer, Director of Health and Safety for IUOE Local 478, 
testified that the competent person could respond to changing 
conditions by repositioning equipment so that employees are upwind of 
the dust created, adjusting water controls based on environmental 
factors, or addressing an unexpected encounter of a concrete sub-base 
during asphalt milling (Document ID 3583, Tr. 2351-2352).
    Commenters also addressed a competent person's role regarding 
bystanders (i.e., employees working nearby other employees who are 
engaged in tasks that generate respirable crystalline silica but are 
not themselves engaged in those tasks). BCTD commented that the 
potential for bystander exposure is another reason why competent 
persons are needed in construction (Document ID 4223, p. 110). Hearing 
participants described how a competent person could minimize bystander 
exposure. For example, Travis Parsons, Senior Safety and Health 
Specialist for LHSFNA, stated that the competent person could ensure 
communication about exposures being generated between employees from 
different trades working at the same construction site (Document ID 
3589, Tr. 4232). Donald Hulk, Safety Director for Manafort Brothers, 
Inc. and representing IUOE, testified that a sufficiently trained 
competent person would be able to recognize when secondary exposures 
could occur, and in those situations, subcontractors might be able 
reschedule activities to avoid bystander exposures (Document ID 3583, 
Tr. 2385-2386).
    Another reason why commenters stated that a competent person is 
needed in construction is because they thought that employers are not 
adequately recognizing respirable crystalline silica-related health 
hazards. As evidence that employers do not believe that respirable 
crystalline silica is an issue, Chris Trahan, CIH, representing BCTD, 
pointed to the volume of testimony claiming that declining silicosis 
mortality rates are evidence that silicosis is not a problem and that 
respirable crystalline silica is an ``alleged carcinogen.'' Ms. Trahan 
disagreed with these commenters and said their testimony demonstrates 
the hurdles that the industry must overcome before silica is recognized 
as a hazard and controlled (Document ID 3581, Tr. 1641-1642; 4223, pp. 
108-109). LHSFNA claimed that most contactors have not adequately 
addressed respirable crystalline silica-related health hazards because 
of the long latency of silica-related disease compared to the common 
short tenure of employment at any one company. LHSFNA commented that 
this blunted the ability of workers' compensation to provide an 
incentive for disease prevention (Document ID 4207, p. 3). In support 
of the importance of a competent person for preventing disease, LHSFNA 
and BCTD pointed to the following statement in the AIHA White Paper on 
competent persons (Document ID 3589, Tr. 4199; 4223, p. 106).

    A key component in preventing overexposure to silica and 
subsequent disease is to have at least one individual on the jobsite 
who is capable of recognizing and evaluating situations where 
overexposure may be occurring; who knows how to evaluate the 
exposure potential; and who can make an initial recommendation on 
how to control that exposure. This is the role of the silica 
competent person (Document ID 4076, p. 3).

    Commenters stressed that the competent person is a well-known 
concept in construction. LHSFNA and BCTD commented that requiring a 
competent person under the silica regulation maintains consistency with 
19 OSHA construction standards (Document ID 4207, p. 3; 4223, p. 107). 
Standards requiring a competent person include asbestos (29 CFR 
1926.1101), lead (29 CFR 1926.62), and cadmium (29 CFR 1926.1127) 
(Document ID 4223, p. 107). In addition, NIOSH and LHSFNA commented 
that competent person provisions are commonly included in American 
National Standard Institute (ANSI) standards for construction (Document 
ID 2177, Attachment B, p. 8; 3589, Tr. 4200). NIOSH further said that 
it and its state partners routinely recommend the need for, and role 
of, designated competent persons in investigation reports conducted 
under NIOSH's Fatality Assessment and Control Evaluation program 
(Document ID 2177, Attachment B, p. 8).
    The competent person requirement is also consistent with 
construction industry practices. For example, Donald Hulk testified 
that at Manafort Brothers construction sites, a highly trained person 
has the authority to ensure that best practices are implemented 
(Document ID 3583, Tr. 2380). Anthony Zimbelman testified that owners 
or competent persons of subcontracting companies conduct assessments 
and develop procedures for controlling dust before remodeling or 
construction of homes (Document ID 3587, Tr. 3538-3539). Safety 
Director Francisco Trujillo from Miller and Long, Inc. testified ``. . 
. we have competent persons for almost everything . . .'' and explained 
that competent persons are required to

[[Page 16808]]

evaluate the adequacy of protective equipment when dust collection 
systems are used because of the limitations of those systems and 
changing site conditions (Document ID 3585, Tr. 2963-2964, 2980).
    Specific duties for a competent person were recommended by a 
diverse group of commenters, including AIHA, NIOSH, National Asphalt 
Pavement Association (NAPA), IUOE, National Rural Electric Cooperative 
Association (NRECA), retired occupational safety and health attorney 
Charles Gordon, LHSFNA, and BCTD (Document ID 2169, p. 5; 2177, 
Attachment B, pp. 9-10, 14; 2181, pp. 10-11; 2262, pp. 38-39, 42-43; 
2365, pp. 19-20; 3588, Tr. 3800-3801; 3589, Tr. 4197-4201; 4223, pp. 
106-114). BCTD, which had among the most extensive recommendations, 
noted that OSHA standards for lead, asbestos, and cadmium specify 
duties for a competent person (Document ID 4223, p. 112). For the 
respirable crystalline silica standard, BCTD requested that the 
employer designate a competent person to be on site whenever work 
covered by the standard is being conducted to ensure that the 
employer's written exposure control plan is implemented, and to:

. . . use the written exposure control plan to identify locations 
where silica is present or is reasonably expected to be present in 
the workplace prior to the performance of work. In addition the 
competent person's duties shall include ensuring: (1) The employer 
has assessed the exposures as required by this section; (2) where 
necessary, regulated areas are established and access to and from 
those areas is limited to authorized persons; (3) the engineering 
controls and work practices required by this standard, including all 
elements of Table 1 (if it is being used), are fully and properly 
implemented, maintained in proper operating condition, and 
functioning properly; (4) employees have been provided with 
appropriate PPE, including respiratory protection, if required; and 
(5) that all employees exposed to silica have received the 
appropriate silica training . . . (Document ID 4223, p. 113).

    NIOSH recommended similar duties in addition to indicating that the 
competent person should assure proper hygiene to prevent employees from 
taking home silica dust on clothing and to conduct daily checks of 
engineering controls and respirators in abrasive blasting operations 
involving sand (Document ID 2177, Attachment B, pp. 9-10, 14). IUOE 
stated that the competent person could assist with employee training, 
ensure good housekeeping in heavy equipment cabs, and assume 
responsibility for exposure assessments (Document ID 2262, p. 41; 3583, 
Tr. 2369-2370; 3583, Tr. 2345). NISA stated that a competent person 
could conduct qualitative objective exposure assessments or determine 
frequency of exposure estimates under the performance option (Document 
ID 2195, pp. 35-36).
    CISC opposed a requirement for a competent person and stated that 
thorough training eliminated the need for a competent person and access 
control plan (Document ID 4217, pp. 25-26). In disputing the value of 
expanding the competent person role in the standard, CISC claimed that 
the ubiquitous presence of silica in construction precluded the need 
for a designated person who is capable of identifying existing and 
predictable respirable crystalline silica hazards and has authorization 
to take prompt corrective actions (Document ID 2319, p. 127).
    Commenters also addressed the practicality of a competent person 
requirement. IUOE commented that an employer would not need to hire 
additional personnel to serve as silica competent persons because they 
could designate a competent person to oversee more than one 
construction activity or task, as long as that person is able to 
identify existing and predictable hazards and is authorized to take 
prompt corrective action (Document ID 4234, Part 3, pp. 62-63). In 
contrast, CISC commented that requiring a competent person at all 
construction sites is not realistic for small companies and pointed to 
testimony from Kellie Vazquez, Vice President of Holes Incorporated, as 
an example (Document ID 4217, pp. 26-27). Ms. Vazquez testified:

. . . my guys are one-man crews. So I will have one operator in a 
truck and that truck is loaded with his equipment to go do his 
multiple jobs per day. He is his own operator, his own equipment 
operator, his own supervisor, his own foreman. He has the right to 
shut down any job he feels that is not safe. I don't have a second 
man, or a competent person, or a supervisor go with him on site to 
look at the job and verify if it is safe or not. That's his 
responsibility. That's what he is trained to do. My operators have 
30-hour OSHA [training]. They are trained in trenching and 
excavation. They are competent people in trenching and excavation. 
They are scaffold builders. They get aerial lift trained (Document 
ID 3580, Tr. 1389).

    OSHA observes that the description of Ms. Vazquez's employees is 
consistent with the definition of a competent person for safety issues 
(i.e., extensive training on safety issues and the authority to close 
down a job site if they feel that it is not safe), and Ms. Vazquez 
admitted that her employees are already competent persons in trenching 
and excavation. It is likely that her employees already have the 
knowledge to fully and properly implement controls on the tools they 
use and recognize if they are not functioning properly. With the 
training required under paragraph (i) of the standard for construction 
and the authority to take corrective actions, those employees could be 
designated as competent persons for respirable crystalline silica. OSHA 
concludes there is no need to designate a separate competent person in 
that situation.
    In addition, any prompt corrective measures that competent persons 
would take to eliminate or minimize respirable crystalline silica 
hazards would likely have minimal impact on work activities in most 
cases. Such measures might include briefly stopping work to clear a 
clogged water line on a tool with wet method controls or clean a filter 
on a tool with vacuum controls if the competent person sees signs that 
controls are not functioning effectively. OSHA concludes that even for 
small businesses, a competent person requirement will not be unduly 
burdensome because knowledgeable employees, who will already be on 
site, can be designated as competent persons.
    OSHA concludes that the ubiquitous presence of respirable 
crystalline silica and the many variables that can affect employee 
exposure when performing construction tasks justify a requirement for a 
competent person in construction, who is not only trained to identify 
and correct respirable crystalline silica hazards, but also is 
authorized to take immediate corrective actions to eliminate or 
minimize them.
    Exposures and hazards can vary according to environmental 
conditions such as wind and humidity, geological profile of soil, if 
work is performed indoors or outdoors, or how well exposure controls 
are maintained. Consequently, there is an obvious need for a competent 
person to frequently inspect the construction job site, identify 
respirable crystalline silica hazards, and verify that effective 
control measures are being used. Site assessment is a continuous 
process because of changing environmental and work conditions as a 
construction job is being completed. In cases where the competent 
person is the only person from his or her company on a job site, 
frequent inspections of the job site would equate to continuous 
assessment of variables associated with the job that the competent 
person is conducting (e.g., signs that the controls are not functioning 
effectively, a change in weather condition that might require an 
adjustment of controls, or moving from an outdoor area to an enclosed 
area).

[[Page 16809]]

Therefore, paragraph (g)(4) of the standard for construction requires 
an employer to designate a competent person to make frequent and 
regular inspections of job sites, materials, and equipment to implement 
the written exposure control plan. OSHA concludes that the uniqueness 
and complexity of scenarios on construction sites justify the 
designation of a competent person.
    OSHA agrees with commenters that a competent person is needed in 
construction because employers who use the specified exposure control 
methods in Table 1 are not required to conduct exposure assessments and 
because large numbers of small construction companies do not typically 
employ health and safety professionals. Another reason for including a 
competent person provision in the construction standard is because at 
multi-employer worksites, the actions of one employer may expose 
employees of other employers to hazards. For these reasons, OSHA agrees 
with ACCSH and commenters from NIOSH, labor unions, and employee health 
advocate groups that a requirement for a designated competent person is 
needed and will improve employee protections in construction.
    In addition, as noted above, a requirement for a competent person 
is consistent with OSHA substance-specific standards for construction, 
such as lead (29 CFR 1926.62), asbestos (29 CFR 1926.1101), and cadmium 
(29 CFR 1926.1127). OSHA's general safety and health provisions for 
construction require the employer to initiate and maintain programs for 
accident prevention, as may be necessary, and such programs require 
frequent and regular inspections of job sites, materials, and equipment 
by a designated competent person (29 CFR 1926.20(b)(1) and (2)). 
Designating a competent person is consistent with current construction 
industry practices because, as the record indicates, employers in the 
construction industry are already using competent persons.
    OSHA is requiring that the competent person implement the written 
exposure control plan because, as discussed above, the plan specifies 
what must be done to consistently identify and control respirable 
crystalline silica hazards on a job site. In construction, a competent 
person is needed to ensure that the requirements of the written 
exposure control plan are being met under variable conditions. The 
subjects that must be described in the written exposure control plan 
for construction--tasks involving exposure to respirable crystalline 
silica; engineering controls, work practices, and respiratory 
protection; housekeeping methods for limiting exposure; and procedures 
for restricting access when needed to minimize exposures or numbers of 
employees exposed--are consistent with the duties of a competent person 
suggested by representatives from NIOSH, labor unions, employee health 
advocates, and some industries. Therefore, having the competent person 
implement the written exposure control plan is consistent with many of 
the competent person duties recommended by commenters. It also makes 
the competent person requirements easy to understand.
    Implementation of the written exposure control plan does not 
address every competent person duty that was recommended by commenters, 
such as training or specific duties related to abrasive blasting with 
sand. OSHA is not mandating that the competent person conduct training 
because training could, in many cases, be performed by other 
individuals. For example, ensuring that an employee can demonstrate 
knowledge and understanding of health hazards, contents of the rule, 
and medical surveillance, and providing the employee with any needed 
training, may be better addressed by an individual other than the 
designated competent person, or at another location before the employee 
reports to the job site. A competent person could use the written 
exposure control plan to recognize employees who are not knowledgeable 
about full and proper implementation of controls or work practices and 
take appropriate action, such as reminding them of proper practices or 
recommending additional training to the employer.
    The standard does not specify a duty for the competent person 
regarding abrasive blasting with sand, but unique aspects of that 
operation, such as more frequent checks of controls, could be specified 
in the written exposure control plan. OSHA reasons that evaluating 
alternate media for use in abrasive blasting, as was recommended in the 
draft standard for SBREFA, requires specialized knowledge in toxicology 
or a related science, and is thus beyond the knowledge of a typical 
employee who would be designated a competent person and unduly 
burdensome to employers. Also, as discussed in the summary and 
explanation section of Methods of Compliance, OSHA recognizes that 
alternative media may present health risks. Other duties that 
commenters recommended, such as conducting exposure assessment, are 
usually done by professionals such as industrial hygienists. Requiring 
an industrial hygienist to be on worksites daily would be very 
burdensome, especially to small employers. In addition, OSHA expects 
the need for exposure assessments in construction to be limited because 
most employers will likely rely on Table 1 in paragraph (c) rather than 
do exposure assessments, based on the number of comments OSHA received 
about exposure assessments being impractical in construction (see 
summary and explanation of Exposure Assessment).
    In its prehearing comments, BCTD also requested that the exposure 
control plan list the identity of the competent person (Document ID 
2371, Attachment 1, pp. 16-17). OSHA is not requiring that the written 
exposure control plan include the identity of the competent person 
because it is both impractical and unnecessary. Construction companies 
could have more than one designated competent person because they need 
a backup competent person or they have jobs being conducted at various 
construction sites. Therefore the identity of the competent person 
could change from day to day if employees work at different job sites, 
or if a backup person is sent to a particular job site. However, it is 
important for employees to be able to identify the competent person. 
Therefore, OSHA is requiring that employers covered by the standard for 
construction notify employees about the identity of the competent 
person as part of the training provision under paragraph (i)(2)(i)(E). 
OSHA expects this could simply involve announcing the identity of the 
competent person at the start of each work shift.
    As stated above, paragraph (b) (Definitions) of the standard for 
construction specifies that the competent person have the knowledge and 
ability necessary to fulfill his or her responsibilities. The proposed 
rule did not specify particular training requirements for competent 
persons. Rather, the requirement for a competent person was 
performance-based in that the competent person needed to be capable of 
effectively performing the duty assigned under the standard, which was 
to identify, in advance, areas where exposures were reasonably expected 
to exceed the PEL. In the standard for construction, the duties of the 
competent person have been expanded, and expanded training requirements 
for the competent person therefore need to be considered.
    OSHA received many comments regarding knowledge and competencies 
for a competent person. IUOE recommended inclusion of specific training 
requirements for competent persons in the standard for construction

[[Page 16810]]

because it thought that without them, competent persons may not get the 
training needed to train employees in the implementation and 
maintenance of controls or understand and adjust to variables that 
affect exposures, smaller employers might not understand the scope of 
appropriate training, employers might avoid expenditures for 
appropriate training, and the standard would be more difficult to 
enforce (Document ID 4234, Part 2, p. 52). IUOE summarized one case 
concerning an occupational fatality resulting from inadequate training 
or knowledge and other cases supporting specific training for competent 
persons (Document ID 4234, Part 2, pp. 55-56). ASSE cautioned that many 
OSHA standards do not specify parameters for determining competency and 
referred to the challenges in judging competency when litigating 
citations (Document ID 4201, pp. 4-5).
    NIOSH requested that OSHA require competency training, as it did 
for asbestos (29 CFR 1926.1101(o)(4)), and list requirements for 
silica-specific training and capabilities for competent persons in the 
standard or an appendix of the standard. NIOSH further stated that 
``OSHA could consider allowing appropriate experience to qualify (e.g., 
learning by apprenticing to a trained silica-competent person).'' NIOSH 
noted that such an approach is consistent with the ANSI A10.38 standard 
that defines a competent person based on specific education, training, 
or experience (Document ID 2177, Attachment B, p. 9).
    IUOE, ASSE, LHSFNA, and BCTD endorsed the competency objectives set 
forth in an AIHA White Paper as a minimum body of knowledge for a 
silica competent person (Document ID 4201, p. 6; 4207, p. 3; 4223, pp. 
113-114). BCTD requested that the White Paper be included as a non-
mandatory appendix to the rule (Document ID 4223, pp. 113-114). The 
AIHA White Paper indicates that a silica competent person can 
demonstrate competency by completing a training course addressing the 
criteria in the White Paper or successfully demonstrating the 
capabilities described in the White Paper through training or direct 
job experience. The competency objectives listed in the AIHA White 
Paper include an understanding of (a) the role of a competent person; 
(b) what silica is and where it is found; (c) silica hazards and 
exposures, occupational exposure limits, and regulations; (d) how to 
determine if silica is present through bulk sample analyses, safety 
data sheets, or material checklists; (e) exposure ranges for common 
construction tasks in the absence of controls and under conditions that 
can result in higher exposures, and recognition of situations when a 
qualified person needs to be called in; (f) effective use of controls 
to reduce exposures and basic understanding of respiratory protection; 
(g) understanding of need for oversight and quality assurance, 
including review of exposure monitoring by a qualified person and 
communication to other employers on a multi-employer sight; (h) 
understanding of OSHA standard; and (i) understanding of authority, 
responsibilities and procedures (e.g., resolving safety or health 
situations) (Document ID 4076, pp. 4-9).
    Commenters further elaborated on training requirements and 
competencies for a silica competent person. ASSE requested that OSHA 
give clear guidance on what qualifies an individual to be designated a 
competent person, asserted that certification in safety or industrial 
hygiene should presume competency, recommended similar competency 
requirements as the AIHA White Paper, and suggested that OSHA include 
training competency requirements in a non-mandatory appendix. ASSE also 
noted that the asbestos standard, 29 CFR 1926.1101(o)(4), requires 
competent persons to complete an Environmental Protection Agency 
course, and although an equivalent course does not exist for 
crystalline silica, training to address competencies for a silica 
competent person could be added to a 30-hour course for construction 
(Document ID 4201, pp. 2-6).
    As discussed in detail in the summary and explanation of 
Communication of Respirable Crystalline Silica Hazards to Employees, 
BCTD requested a tiered approach to training in which the competent 
person would receive training necessary to perform his or her duties, 
in addition to awareness training for all covered employees and hands-
on training on engineering controls and work practices for employees 
performing tasks that generate silica dust (Document ID 4223, pp. 117-
118). IUOE, LHSFNA, and BAC similarly advocated competent person 
training as part of a tiered approach and stressed that the competent 
person receive site-specific training on engineering controls (Document 
ID 2262, pp. 39-40; 4207, p. 5; 4219, p. 24). Tom Nunziata, Training 
Coordinator for LHSFNA, stressed that the minimum training for a 
competent person should be at least the training required for employees 
performing tasks that generate silica dust (Document ID 3589, Tr. 
4221). Similar to NIOSH, Travis Parsons testified that experience can 
contribute to a competent person's knowledge (Document ID 3589, Tr. 
4197-4198).
    LHSFNA indicated that competent person training should be tailored 
based on needs and exposure potential (Document ID 4207, p. 5). Other 
commenters provided numerous examples of unique training requirements 
for heavy equipment operators. For example, Gary Fore, retired Vice 
President for Health, Safety, and Environment for NAPA, referenced best 
practices for inspection of controls on asphalt milling machines by 
competent persons and testified that those machines are very 
complicated and sophisticated (Document ID 3583, Tr. 2182-2183). 
Therefore, training is required to detect issues requiring maintenance, 
such as a plugged or inappropriately placed nozzle (Document ID 2181, 
p. 10). IUOE commented that a competent person must have the knowledge 
to make informed judgments about the potential for silica exposures to 
exceed the action level (Document ID 2262, pp. 42-43). Martin Turek, 
Assistant Coordinator and Safety Administrator for IUOE Local 150, and 
Kyle Zimmer gave several examples of variables that could affect silica 
exposures in earth moving tasks, such as weather (e.g., wind, humidity) 
and soil compositions and handling (e.g., clay versus rock, distance 
soil is dropped from a bucket) (Document ID 3583, Tr. 2351-2352, 2356-
2359). Matt Gillen, Deputy Director of NIOSH's Office of Construction 
Safety and Health, testified that a competent person should be able to 
recognize variability issues and make changes to address them (Document 
ID 3579, Tr. 205-206).
    NRECA commented that a competent person for rural electric 
utilities should be trained in setting up air monitoring, setting 
boundaries for control zones, physical characteristics of crystalline 
silica, and PPE such as respirators (Document ID 2365, pp. 19-20). 
Francisco Trujillo testified that a competent person should have 
knowledge of work processes and their associated hazards and possibly, 
some knowledge of previous sampling evaluations to know if employees 
might be overexposed (Document ID 3585, Tr. 2980-2981). Upstate Medical 
University recommended that the competent person be trained on the 
respirable crystalline silica standard, the hierarchy of controls, 
exposure determinants, and the written control plan (Document ID 2244, 
p. 4).
    Ameren Corporation opposed specific training requirements for a 
competent person (Document ID 2315, p. 2). CISC stated that if OSHA 
does include a competent person requirement in the

[[Page 16811]]

standard, the agency should not require training because:

    An individual's experience, job training, and silica awareness 
training, in the CISC's view, will provide the capabilities 
envisioned by OSHA for a competent person with respect to 
crystalline silica. For silica in construction, the CISC 
respectfully believes that no specific training for a ``competent 
person'' is required. Furthermore, the Agency has traditionally not 
included specific competent person training requirements in its 
construction standards, instead taking a performance-oriented 
approach to the requirements and definition. There is nothing unique 
about silica that would cause the Agency to deviate from this past 
approach (Document ID 2319, pp. 127-128).

    OSHA concludes, after consideration of all the comments, that it is 
not practical to specify in the rule the elements and level of training 
required for a competent person. The Agency does not find it 
appropriate to mandate a ``one size fits all'' set of training 
requirements to establish the competency of competent persons in every 
conceivable construction setting. Therefore, the training requirement 
for a competent person is performance-oriented. This approach is 
consistent with most OSHA construction standards, such as cadmium (29 
CFR 1926.1127) and lead (29 CFR 1926.62), which include a performance-
based approach by not specifying training or qualifications required 
for a competent person.
    It is evident from the comments that controlling respirable 
crystalline silica exposures involves tailoring controls and work 
practices to each particular work setting. Moreover, training is 
addressed by the HCS and paragraph (i) of the standard for 
construction. The HCS and paragraph (i) require that employees be 
trained on subjects that overlap with competencies listed in the AIHA 
White Paper. For example paragraph (h)(3)(i) of the HCS (29 CFR 
1910.1200) requires training of covered employees on methods to detect 
the release of hazardous chemicals (in this case, respirable 
crystalline silica). The respirable crystalline silica standard for 
construction requires training on health hazards, tasks that could 
result in exposures, engineering and work practice controls and 
respiratory protection, and the contents of the standard (paragraphs 
(i)(2)(i)(A-D)).
    OSHA concludes that successful completion of training requirements 
in the HCS and the standard for construction impart a high level of 
competency to employees. The training focuses on general requirements 
that apply to most construction settings and should be sufficient to 
provide an employee with the knowledge and ability to be designated a 
competent person at some companies. Competent persons might require 
more knowledge and training in certain circumstances, but that would 
vary widely among construction companies. For example, competent 
persons at a small residential construction company might only need 
training on controls for power tools that they do not typically use to 
perform their own tasks, so that they could assist employees with 
questions about or problems with dust controls on those tools. In 
contrast, a competent person for heavy equipment tasks may require more 
specialized training in heavy equipment inspection or identifying 
various soil types to estimate exposure potential. Because companies 
covered under the construction standard conduct a wide range of tasks 
involving unique scenarios, training requirements will vary widely 
among different companies. It is, therefore, the employer's 
responsibility to identify and provide any additional training that the 
competent person needs to implement the employer's written exposure 
control plan.
    Finally, a compliance officer could ascertain whether the employer 
is in compliance with the competent person requirement by asking 
questions to assess whether the competent person has adequate knowledge 
to perform his or her duties, such as an understanding of engineering 
controls and how to recognize if they are not functioning properly. As 
is the case with training of all employees, the employer is responsible 
for determining that a competent person is adequately trained and 
knowledgeable to perform his or her duties.
    Competent Person (General Industry). As part of the proposed 
written access control plan, OSHA proposed that a competent person 
identify and maintain regulated areas in workplaces covered by the 
general industry and maritime standard. AFL-CIO and USW requested 
expanded competent person duties and training requirements for general 
industry and maritime because a competent person could recognize and 
take action to protect employees from high exposures (Document ID 4204, 
pp. 58-60; 4214, pp. 14-16). AFL-CIO urged OSHA to reinstate the 
competent person duties from the 2003 SBREFA draft standard (Document 
ID 4204, pp. 58-60). USW commented that a competent person could ensure 
that hazards are recognized, employees receive proper training, 
adequate controls and PPE are implemented, and an effective exposure 
control plan is developed (Document ID 4214, pp. 14-15). In describing 
how a competent person is relevant to general industry, AFL-CIO pointed 
to testimony by employees who were trained to evaluate the function of 
ventilation systems (Document ID 4204, p. 60). AFL-CIO also asserted 
that NIOSH and AIHA urged OSHA to include a competent person 
requirement for both general industry and construction (Document ID 
4204, pp. 59-60). OSHA examined the AIHA and NIOSH comments referenced 
by AFL-CIO and identified only recommendations for a competent person 
regarding construction-related topics, such as Table 1 (Document ID 
2169, pp. 4-5; 2177, Attachment B, pp. 8-10, 25-26).
    OSHA is not requiring a competent person for the general industry 
and maritime standard. OSHA has determined that in most cases, general 
industry scenarios are not as variable as those in construction. For 
example, most work is performed indoors and therefore, not subject to 
variables such as wind shifts and moving exposure sources that could 
significantly affect exposures or complicate establishment of regulated 
areas. In general industry and maritime, controls are not usually built 
into tools that require action by the individual employees who use them 
to function effectively. The exposure assessments that employers in 
general industry and maritime are required to conduct will verify that 
controls are functioning effectively. Employers covered under the 
general industry and maritime standard are more likely to have health 
and safety professionals on staff who could assist with implementation 
of the standard. Finally, competent persons have not been included in 
other OSHA substance-specific standards for general industry. For 
example, a competent person requirement was included in the 
construction standard for cadmium because of environmental variability 
and the presence of multiple employers on the job site, but a competent 
person requirement was not included in the general industry standard 
for cadmium (29 CFR 1910.1027; 29 CFR 1926.1127; 57 FR 42101, 42382 (9/
14/1992)). Moreover, as explained in the summary and explanation of 
Regulated Areas, establishing regulated areas is reasonable in most 
general industry scenarios because employers are required to conduct 
exposure assessment and are thus able to determine the boundaries of a 
regulated area. Therefore, the general industry and maritime standard 
requires regulated areas that are demarcated and posted with warning 
signs. This negates the

[[Page 16812]]

need for a competent person to identify and maintain regulated areas. 
These factors explain and support OSHA's conclusion that there is no 
regulatory need for including a competent person requirement in the 
respirable crystalline silica standard for general industry and 
maritime.
    Comparison to ASTM Standards. The written exposure control plan is 
comparable to the ASTM standards in some respects and different in 
others. Section 4.2.6 of ASTM Standard E 1132-06 and Section 4.2.5 of 
ASTM standard E 2625-09 recommend written exposure control plans for 
areas with persistent overexposures; address engineering, work 
practice, and administrative controls; and call for a root cause 
analysis to investigate the causes of the overexposure, identify 
remedies, and conduct follow-up sampling to verify that exposures are 
below the PEL (Document ID 1466, p. 2; 1504, p. 2). The major 
difference between the written plans in the ASTM standards and the 
written plans in the respirable crystalline silica rule is that the 
written plans for the respirable crystalline silica rule are not 
limited to overexposure scenarios. The ASTM standards address work 
practices and administrative controls, but the written exposure control 
plans in the respirable crystalline silica rule further explain what 
those practices and controls are (i.e., restricting access as needed 
(construction standard only), engineering controls, work practices, 
respiratory protection, and housekeeping methods). In addition, the 
written exposure control plans in the respirable crystalline silica 
rule are implemented by a competent person (construction standard 
only), are required to be reviewed and updated at least annually by the 
employer, and are to be made available to employees, employee 
representatives, OSHA, and NIOSH upon request.
    The requirements of the rule for respirable crystalline silica 
better protect employees and, therefore, better effectuate the purposes 
of the OSH Act of 1970 than the ASTM standards. Because the written 
plans are required for all workplaces covered by the rule, they help to 
maintain comprehensive and consistent controls, which can prevent 
overexposures from occurring. The provision for annual review ensures 
that the plans remain effective, and the provision for making the plans 
available to employees helps to make employees aware of the protections 
they should expect. More details about how the requirements of the rule 
better effectuate the requirements of the OSH Act are discussed above.

Medical Surveillance

    Paragraph (i) of the standard for general industry and maritime 
(paragraph (h) of the standard for construction) sets forth 
requirements for the medical surveillance provisions. The paragraph 
specifies which employees must be offered medical surveillance, as well 
as the frequency and content of medical examinations. It also sets 
forth the information that the physician or other licensed health care 
professional (PLHCP) is to provide to the employee and employer.
    The purpose of medical surveillance for respirable crystalline 
silica is, where reasonably possible, (1) to identify respirable 
crystalline silica-related adverse health effects so that appropriate 
intervention measures can be taken; (2) to determine if an employee can 
be exposed to respirable crystalline silica in his or her workplace 
without increased risk of experiencing adverse health effects, or in 
other words, to determine if an employee has any condition, regardless 
of the cause, that might make him or her more sensitive to respirable 
crystalline silica exposure; and (3) to determine the employee's 
fitness to use respirators. The inclusion of medical surveillance in 
this rule is consistent with Section 6(b)(7) of the Occupational Safety 
and Health (OSH) Act (29 U.S.C. 655(b)(7)) which requires that, where 
appropriate, medical surveillance programs be included in OSHA 
standards to determine whether the health of employees is adversely 
affected by exposure to the hazard addressed by the standard. Almost 
all other OSHA health standards have also included medical surveillance 
requirements and OSHA finds that a medical surveillance requirement is 
appropriate for the respirable crystalline silica rule because of the 
health risks resulting from exposure.
    General. Paragraph (i)(1)(i) of the standard for general industry 
and maritime requires employers to make medical surveillance available 
for employees who will be occupationally exposed to respirable 
crystalline silica at or above the 25 [mu]g/m\3\ action level for 30 or 
more days per year. Paragraph (h)(1)(i) of the standard for 
construction requires employers to make medical surveillance available 
to employees who will be required under this section to use a 
respirator for 30 or more days per year. Thus, employers are required 
to determine if their employees will be exposed at or above the action 
level of 25 [mu]g/m\3\ in general industry and maritime, or required to 
wear a respirator under the construction standard for 30 or more days 
per year (i.e., the next 365 days), and then make a medical examination 
available to those employees who meet these criteria under two 
scenarios: (1) Within 30 days of initial assignment, unless the 
employee has had a current examination that meets the requirements of 
this rule within the last three years (paragraph (i)(2) of the standard 
for general industry and maritime, paragraph (h)(2) of the standard for 
construction) and (2) within three years from the last initial or 
periodic examination (paragraph (i)(3) of the standard for general 
industry and maritime, paragraph (h)(3) of the standard for 
construction). As in previous OSHA standards, both standards are 
intended to encourage participation by requiring that medical 
surveillance be offered at no cost to the employee and at a reasonable 
time and place. Under the ``at no cost to the employee'' proviso, if 
participation requires travel away from the worksite, the employer will 
be required to bear the cost of travel, and employees will have to be 
paid for time spent taking medical examinations, including travel time.
    Some employers and industry representatives questioned the general 
need for medical surveillance or expressed their concerns with the 
medical surveillance requirement. For example, OSCO Industries, Inc. 
argued that medical surveillance would not identify many employees with 
silicosis and OSCO Industries and National Association of Home Builders 
(NAHB) emphasized the progress that has already been made in 
eliminating silicosis (Document ID 1992, p. 11; 2296, p. 43). Fann 
Contracting, Inc. stated that medical surveillance is not needed 
because employees exposed above the permissible exposure limit (PEL) 
are required to wear respirators and they should therefore be protected 
(Document ID 2116, Attachment 1, p. 43).
    OSHA does not find these comments persuasive. As discussed in 
Section VI, Final Quantitative Risk Assessment and Significance of 
Risk, OSHA has found that employees exposed to respirable crystalline 
silica at the preceding PELs are at significant risk of material 
impairment of health. Although the revised PEL of 50 [mu]g/m\3\ 
substantially decreases risks, the risk remains significant at and 
below the PEL, including at the action level of 25 [mu]g/m\3\. 
Consequently, even employees exposed at the action level are at 
significant risk of developing silicosis and other respirable 
crystalline silica-related diseases. Based on these risk assessment 
findings, OSHA concludes that silicosis and other respirable

[[Page 16813]]

crystalline silica-related illnesses are an ongoing occupational risk. 
OSHA expects that those illnesses are likely to be detected as part of 
medical surveillance, and the detection of these illnesses will benefit 
employees.
    Even employees required to wear respiratory protection in high 
exposure environments are at risk of developing disease. As OSHA notes 
in the summary and explanation of Methods of Compliance, respirators 
fully protect employees only if they are properly fitted and maintained 
correctly and replaced as necessary; they do not protect employees if 
they are not used consistently and properly. The committee that 
developed the ASTM International (ASTM) standard, ASTM E 2625-09, 
Standard Practice for Controlling Occupational Exposure to Respirable 
Crystalline Silica for Construction and Demolition Activities, also 
concluded that medical surveillance is needed for employees who wear 
respirators to ensure that the respiratory protection is working 
(Document ID 3580, Tr. 1452). (This requirement is consistent with that 
in ASTM E 1132-06, Standard Practice for Health Requirements Relating 
to Occupational Exposure to Respirable Crystalline Silica.) 
Consequently, OSHA concludes that the requirement for respiratory 
protection for exposures exceeding the PEL does not obviate the need 
for medical surveillance.
    Employers also expressed concern about responsibility for exposures 
occurring through other employment or non-occupational sources (e.g., 
environmental exposures) (e.g., Document ID 2116, Attachment 1, pp. 20, 
36, 37, 39; 2295, p. 2; 2296, p. 31; 3531, p. 9). Construction Industry 
Safety Coalition (CISC) and Holes Incorporated questioned how medical 
surveillance would decrease exposures, and Holes Incorporated stated it 
would not prevent the onset of silicosis (Document ID 2319, p. 116; 
2338, p. 6).
    OSHA stresses that the main purposes of medical surveillance are 
early detection of disease related to respirable crystalline silica 
exposure so appropriate intervention methods can be taken, to let 
employees know if they have a condition that might make them more 
sensitive to respirable crystalline silica exposure, and to assess 
fitness to wear a respirator. The purpose of medical surveillance is 
not to identify which employer is responsible for illnesses resulting 
from respirable crystalline silica exposures or must offer financial 
compensation. OSHA agrees with the Building Construction and Trades 
Department, AFL-CIO (BCTD), which stated that ``[e]arly detection of 
silica-related medical conditions will enable employees to make 
informed decisions about their work, their medical care and their 
lifestyles'' (Document ID 4223, p. 123). For example, as the American 
College of Occupational and Environmental Medicine (ACOEM) and the 
National Institute for Occupational Safety and Health (NIOSH) stated, 
an early diagnosis allows an employee to consider employment choices 
that minimize or eliminate respirable crystalline silica exposure to 
decrease the risk of progression or exacerbation of disease (Document 
ID 1505, p. 3; 3579, Tr. 257). In another example, an early diagnosis 
of silicosis allowed bricklayer Dennis Cahill, representing the 
International Union of Bricklayers and Allied Craftworkers (BAC), to 
manage his health by getting flu and pneumonia shots, avoiding the 
public during cold season, and staying indoors during periods of high 
air pollution (Document ID 3585, Tr. 3089, 3104). OSHA finds that 
although medical surveillance does not reduce exposures, like 
engineering controls do, it is nonetheless an integral component of 
this (and most) occupational safety and health standards and important 
in its own right for safeguarding the health of employees exposed to 
respirable crystalline silica.
    OSHA also agrees with the viewpoint expressed so well by Mr. 
Cahill, that employees who are knowledgeable about their health risks 
will take actions in response to information from medical surveillance. 
Such actions will likely benefit not only the employees but also 
employers because their employees are likely to be healthier. Members 
of the medical community, labor unions, employee health advocate 
groups, and industry groups emphasized the value of early detection for 
intervention purposes (e.g., Document ID 2080, p. 9; 2178, Attachment 
1, p. 2; 2351, p. 15; 3541, p. 1; 3577, Tr. 570-571; 3588, Tr. 3751; 
3589, Tr. 4292; 4204, p. 79; 4219, p. 28; 4223, pp. 123-124). In 
addition, more than 100 commenters including construction employees, 
employee health advocates, medical professionals, and employers or 
industry representatives voiced their general support for medical 
examinations in the respirable crystalline silica rule (e.g., Document 
ID 1771, p. 1; 2030; 2268; 2134, p. 10; 2403; 3294).
    Some commenters representing the construction industry questioned 
the practicality of medical surveillance for construction employees due 
to a number of particular difficulties, such as the short-term nature 
and high turnover rate of construction jobs (e.g., Document ID 2116, 
Attachment 1, p. 20; 2187, p. 7; 2247, p. 1; 2276, p. 10; 2289, p. 8; 
2295, p. 2; 2296, pp. 42-43; 3230, p. 1; 3442, pp. 5-6; 4029, p. 3; 
4217, p. 21). For example, American Subcontractors Association and Hunt 
Construction Group stated that the difficulty in tracking medical 
surveillance in a mobile work force could result in repeated, 
unnecessary testing for construction employees (Document ID 2187, p. 7; 
3442; pp. 5-6). Kenny Jordan, Executive Director of the Association for 
Energy Services Companies (AESC), which represents another industry 
with high turnover rates, expressed similar concerns about repeated 
testing, although he did not oppose medical surveillance and asked for 
a medical record that would follow the employee (Document ID 3589, Tr. 
4063). The Laborers' Health and Safety Fund of North America (LHSFNA) 
supported medical surveillance, but expressed concerns about repeated 
testing and urged OSHA to include provisions for contractor 
associations and union management funds to coordinate medical 
examinations for employees who work for several contractors in a year 
to avoid unnecessary medical examinations (Document ID 4207, p. 5).
    After considering these comments, OSHA concludes that the necessity 
for medical surveillance is not negated by the practical challenges of 
tracking medical surveillance in a mobile work force. OSHA has included 
medical surveillance in other health standards where construction has 
been a primary industry impacted by those rules (e.g., lead, asbestos, 
and chromium (VI)) and finds no reason why the respirable crystalline 
silica standard for construction should be an exception. Moreover, 
there are practical solutions for tracking medical surveillance to 
avoid duplicative, unneeded testing. One simple solution, which OSHA 
has included in this rule, is to have employers ensure that each 
employee receives a dated copy of the PLHCP's written medical opinion 
for the employer. The employee can then provide the opinion to his or 
her next employer as proof of up-to-date medical surveillance (Document 
ID 4207, p. 5; 4223, p. 125). Employers could also work with a third 
party, such as an industry association, union, or local medical 
facility, to coordinate, provide, or keep records of medical 
examinations (Document ID 4207, p. 5; 4236, pp. 3-4, Appendix 1, pp. 1-
2). Such an approach has been used by LHSFNA to avoid unnecessary 
testing of employees who work for several contractors in a

[[Page 16814]]

year (Document ID 3759, Appendix 3). The respirable crystalline silica 
rule does not preclude such pooled employer-funded approaches, and OSHA 
expects such coordination to occur in response to this rule. OSHA 
concludes that there are practical solutions for addressing the 
challenge posed by employee mobility and turnover in the construction 
industry, and those factors should not prevent construction employees 
who are eligible for medical surveillance under the standard (i.e., 
those who will be engaged in tasks requiring respirator use for 30 or 
more days in the upcoming year) from being offered such surveillance as 
part of the employer's compliance obligations.
    In the proposed standards, OSHA specified that employers must 
``make medical surveillance available'' to those employees who would be 
occupationally exposed to respirable crystalline silica above the PEL 
for 30 or more days a year. The Agency received a variety of comments 
on this provision. First, NAHB expressed concern about employees 
refusing to participate in medical surveillance (Document ID 2296, p. 
32). OSHA emphasizes that the mandate to offer medical surveillance to 
eligible employees does not include a requirement for employee 
participation, and no liability for non-participation arises so long as 
the employer does not discourage such participation.
    Second, OSHA received numerous comments related to the proposed 
triggers for determining which employees should be provided medical 
surveillance. Some commenters focused on the level of exposure at which 
medical surveillance should be triggered. For example, Ameren 
Corporation agreed with the proposed PEL trigger, noting that it is 
consistent with the asbestos standard (Document ID 2315, p. 9). Some 
stakeholders from industry, the medical community, and employee health 
advocate groups also supported a trigger based on a PEL (e.g., Document 
ID 1785, pp. 4-5; 2175, p. 5; 2291, p. 26; 2327, Attachment 1, p. 26; 
2339, p. 5; 2379, Appendix 1, p. 71; 3577, Tr. 784-785).
    Other commenters advocated that medical surveillance should be 
triggered on an action level. However, these stakeholders disagreed on 
what the action level should be. For example, some commenters, like the 
National Industrial Sand Association (NISA), American Petroleum 
Institute, and other employers and industry groups, advocated an action 
level trigger of 50 [mu]g/m\3\ (with a higher PEL of 100 [mu]g/m\3\) 
(e.g., Document ID 1963, pp. 1-2; 2196, Attachment 1, pp. 1-2; 2200, 
pp. 1-2; 2213, p. 3; 2232, p. 1; 2233, p. 1; 2301, Attachment 1, p. 78; 
2311, p. 3; 4208, pp. 7-9). NISA did not agree with OSHA that 
significant risk remains at 50 [mu]g/m\3\, but stated that an action 
level trigger is consistent with other OSHA standards; can lead to 
identification of individuals who might be more susceptible to silica 
exposures because of factors, such as genetic variability, prior work 
exposures, or smoking; addresses variability in workplace exposures; 
and provides an economic incentive for employers to maintain lower 
exposures (Document ID 2195, pp. 6, 30, 32).
    Other stakeholders, including representatives of labor unions, the 
medical community, and other employee health advocate groups, stated 
that the proposed action level of 25 [mu]g/m\3\, or even a lower level, 
should trigger medical surveillance in general industry (e.g., Document 
ID 2157, p. 7; 2178, Attachment 1, p. 2; 2240, p. 3; 2282, Attachment 
3, p. 14; 2336, p. 11; 2256, Attachment 2, p. 9; 2351, pp. 13-15; 3516, 
p. 3; 3541, p. 4). Other members of the medical community and employee 
health advocate groups also voiced general support for an action level 
trigger of 25 [mu]g/m\3\ or lower (e.g., Document ID 2080, p. 5; 2176, 
p. 2; 3538, Attachment 1, pp. 3-4).
    American Federation of Labor and Congress of Industrial 
Organizations (AFL-CIO) supported an action level trigger of 25 [mu]g/
m\3\ because the union agreed with OSHA about the remaining significant 
risk for diseases at a PEL of 50 [mu]g/m\3\ and because an action level 
at half the PEL would be consistent with the majority of OSHA health 
standards (Document ID 4204, pp. 51, 79-80). Other representatives from 
the medical community, labor unions, and other employee health advocate 
groups, who also supported an action level trigger of 25 [mu]g/m\3\ or 
lower, expressed similar thoughts about significant risk or consistency 
with past standards (Document ID 2080, p. 5; 2157, p. 7; 2176, p. 2; 
2178, Attachment 1, p. 2; 2282, Attachment 3, p. 22; 2336, p. 11; 3516, 
p. 3; 3535, p. 2; 3541, pp. 14-15). Some of those same commenters, 
including the United Automobile, Aerospace and Agricultural Implement 
Workers of America (UAW) and ACOEM, supported an action level trigger 
because of the variability of workplace exposures (Document ID 2282, 
Attachment 3, p. 14; 3577, Tr. 766-767); the medical society Collegium 
Ramazzini and United Steelworkers (USW) also noted an economic benefit 
for employers to maintain lower exposures (Document ID 2336, p. 11; 
3541, p. 15). Lastly, AFL-CIO noted that because OSHA proposed a 
requirement for exposure assessment in general industry, employers will 
know if employees are exposed above the action level; the same is not 
true in construction because employers may use Table 1 instead of 
conducting exposure assessments (Document ID 4204, pp. 80-81).
    OSHA also received comments on whether medical surveillance should 
be triggered by a number of days of exposure at a certain level. For 
example, NISA objected to the proposed 30-day exposure-duration trigger 
for medical surveillance and stated that it should be offered to all 
employees with likely exposure to respirable crystalline silica above 
the action level (Document ID 4208, p. 8, Fn 12). The Asphalt Roofing 
Manufacturers Association (ARMA) supported the 30-day exposure-duration 
trigger for medical surveillance because some employees are only 
infrequently exposed above the PEL as a result of scheduled maintenance 
tasks performed once or twice per year or when filling in for other 
employees, and the 30-day trigger would exclude employees with lower 
average exposures (Document ID 2291, p. 26). Other commenters 
representing industry or the medical community also agreed with the 30-
day exposure-duration trigger (e.g., Document ID 2080, p. 5; 2157, p. 
7; 2175, p. 5; 2178, Attachment 1, p. 2; 2301, Attachment 1, p. 78; 
2311, p. 3; 2315, p. 9; 2327, Attachment 1, p. 26; 2379, Appendix 1, p. 
71; 3541, p. 14).
    OSHA agrees with the majority of commenters who indicated that 
maintaining the 30-day exposure-duration trigger is appropriate for 
general industry and maritime because the health effects of respirable 
crystalline silica occur as a result of repeated exposures and 
concludes that a 30-day trigger is a reasonable benchmark for capturing 
cumulative effects caused by repeated exposures. Including a 30-day 
exposure-duration trigger also maintains consistency with other OSHA 
standards, such as chromium (VI) (29 CFR 1910.1026), cadmium (29 CFR 
1910.1027), lead (29 CFR 1910.1025), and asbestos (29 CFR 1910.1001). 
OSHA also agrees with commenters who indicated that triggering medical 
surveillance at the action level of 25 [mu]g/m\3\ addresses residual 
significant risk and varying susceptibility of employees that can 
result in some experiencing adverse health effects at lower exposure 
levels. An action level trigger in the standard for general industry 
and maritime is also appropriate based on variability in exposure 
levels and the availability of exposure assessment data in general

[[Page 16815]]

industry and maritime. However, OSHA has concluded that a delayed 
implementation of the action level trigger for medical surveillance is 
appropriate. Therefore, as indicated in the Summary and Explanation for 
Dates, medical surveillance will be triggered by exposures exceeding 
the PEL for 30 or more days per year during the first two years after 
medical surveillance requirements commence (i.e., beginning two years 
after the effective date). After that time (i.e., four years after the 
effective date), medical surveillance will be triggered by exposures 
exceeding the action level for 30 or more days per year (paragraph 
(l)(4)). This approach will focus initial medical surveillance efforts 
on those employees at greatest risk, while giving most employers 
additional time to fully evaluate the engineering controls they have 
implemented in order to determine which employees meet the action level 
trigger for medical surveillance.
    OSHA intends to conduct a retrospective review five years after the 
action level trigger is fully implemented (i.e., at nine years after 
the effective date of the standard for general industry and maritime) 
to gain a better understanding of the effectiveness of the action level 
trigger for medical surveillance. OSHA will engage other federal 
agencies, such as NIOSH, and stakeholders as appropriate, and will 
issue a report about the findings of the evaluation.
    Construction industry representatives, employee health advocates, 
and others also commented on OSHA's proposed use of the PEL to trigger 
medical surveillance in the standard for construction. The Center for 
Progressive Reform (CPR) and Charles Gordon, a retired occupational 
safety and health attorney, advocated an action level trigger for 
medical surveillance; Mr. Gordon also requested that conducting Table 1 
activities trigger medical surveillance (Document ID 2351, p. 13; 4236, 
pp. 3-4). Fann Contracting supported a PEL trigger for medical 
surveillance (Document ID 2116, Attachment 1, p. 42). BAC and BCTD 
supported the PEL (as determined by monitoring) or Table 1 tasks 
requiring respirator use as triggers for medical surveillance in 
construction because employees using Table 1 would not be required to 
conduct exposure assessments and therefore would not know if exposures 
exceed the action level (Document ID 4219, p. 29; 4223, p. 124). [Note 
1 for proposed Table 1 indicated that required respirator use in Table 
1 presumed exposures exceeding the PEL (78 FR 56273, 56499 (9/12/13))]. 
In prehearing comments, LHSFNA supported a PEL trigger as a practical 
approach and requested that medical surveillance be triggered by tasks 
(Document ID 2253, p. 5). In its post-hearing comments, however, LHSFNA 
recommended that medical surveillance be required for employees who are 
required to wear a respirator since those employees would already need 
to undergo a medical evaluation to make sure they can safely wear a 
respirator (as required by the respiratory protection standard) 
(Document ID 4207, pp. 4-5).
    After reviewing these comments, OSHA concludes that an action level 
trigger is not practical in the construction industry because many 
employers will be using Table 1, and, therefore, will not have an 
exposure assessment indicating if the action level is met or exceeded. 
OSHA acknowledges that some construction employees who are not required 
to use respirators for 30 or more days per year are at significant 
risk, but has decided that triggering medical surveillance based on 
respirator use is the most practical trigger for the construction 
standard. Triggering medical surveillance in this manner is consistent 
with the proposed rule, because respirator use under Table 1 is based 
on tasks in which exposures consistently (more often than not) exceed 
the revised PEL, as found in OSHA's technological feasibility analyses 
of the various tasks included in Table 1 (see Chapter IV of the Final 
Economic Analysis and Final Regulatory Flexibility Analysis (FEA) and 
the summary and explanation for Specified Exposure Control Methods). 
OSHA expects most construction employers to be following Table 1, and 
therefore decided it also made the most practical sense to tie medical 
surveillance to required respirator use. In addition, use of the 
respirator trigger allows construction employers to more efficiently 
determine if the 30-day duration trigger is met in cases where one of 
their employees may be required to use respirators when doing Table 1 
tasks and while doing tasks (e.g., abrasive blasting) that are not on 
Table 1 but are determined to have exposures above the PEL based on 
exposures assessments conducted under paragraph (d)(2) of the standard 
for construction. Finally, OSHA decided not to expand the trigger for 
medical surveillance to Table 1 tasks that do not require respirator 
use because many employees engaged in those tasks will be exposed below 
the action level (see Chapter III of the FEA).
    Some commenters expressed concerns about the practicality of 
requiring employers to offer medical surveillance for exposures 
exceeding a trigger level for 30 days or more in the construction 
industry. George Kennedy, Vice President of Safety for the National 
Utility Contractors Association, testified that they do not know what 
employees are doing in the field each day and so will have to assume 
that they are exposed and, therefore, offer medical surveillance to 
every employee (Document ID 3583, Tr. 2245). BCTD questioned the 
feasibility of the 30-day exposure-duration trigger because the 
transient nature of construction work makes it difficult to predict if 
an employee will be exposed for 30 days; the American Industrial 
Hygiene Association (AIHA), AFL-CIO, and LHSFNA expressed similar views 
(Document ID 2169, p. 6; 4204, p. 81; 4207, p. 4; 4223, p. 125). CISC 
and some of its member companies questioned how an employer would know 
if employees were exposed above the PEL for 30 or more days a year 
unless they were following Table 1 or conducting near continuous 
monitoring (Document ID 2269, pp. 6-7; 2289, p. 8; 2319, p. 116). CISC 
and AIHA questioned how OSHA could verify the number of days an 
employee was exposed (Document ID 2169, p. 6; 2319, p. 116). Larger 
employers, such as Fann Contracting, expressed the challenges of 
tracking employee exposures due to large numbers of employees and 
various ongoing projects (e.g., Document ID 2116, Attachment 1, p. 11).
    OSHA acknowledges that tracking exposures in construction can be 
challenging but observes that some employers are currently able to 
track employee exposures to determine which employees should be offered 
medical surveillance. For example, Kevin Turner, Director of Safety at 
Hunt Construction Group and representing CISC, testified that safety 
representatives on job sites keep track of exposures based on 
employees' schedules, and the company provides medical surveillance for 
employees exposed above the preceding construction PEL for 30 or more 
days a year (Document ID 3580, Tr. 1535-1536). Francisco Trujillo, 
Safety Director at Miller and Long, Inc., testified that at his 
company, they conduct hazard assessments based mainly on the tasks the 
employees will be performing, to determine which employees are likely 
to be exposed above the preceding PEL, and they offer those employees 
medical evaluations as part of the company's respiratory protection 
program. The company has a system that monitors participating 
employees' training, medical evaluations, and fit tests. The system 
sends email reminders to company

[[Page 16816]]

representatives when the participating employees are due to be re-
examined or re-evaluated. However, Mr. Trujillo expressed concern that 
if the number of employees participating in the program greatly 
increases, then maintaining the company's tracking program would become 
a more daunting task (Document ID 3585, Tr. 3008-3010).
    After reviewing the comments and testimony submitted on the 
proposed construction trigger, OSHA concludes that the special 
circumstances in construction, such as lack of exposure data for 
employees using Table 1 or difficulties in tracking exposures for 
numerous short-term assignments conducted at various sites, warrant a 
simpler approach for triggering medical surveillance. Therefore, OSHA 
revised paragraph (h)(1)(i) of the standard for construction to require 
that employers offer medical surveillance to employees who will be 
required to wear a respirator under this standard for 30 or more days a 
year to limit exposure to respirable crystalline silica. Under the 
standard for construction, employees must wear a respirator when 
required to do so under Table 1 (paragraph (c)) or when, pursuant to 
the performance option or the scheduled monitoring option set forth in 
paragraph (d)(2), their exposures exceed the PEL (paragraph 
(e)(1)(ii)). Respirator use under Table 1 is equivalent to the PEL 
because the tasks that require respirator use are those that, in its 
technological feasibility analysis of the construction industry, OSHA 
has determined result in exposures exceeding 50 [mu]g/m\3\ a majority 
of the time (see Chapter IV of the FEA and the summary and explanation 
of Specified Exposure Control Methods). Based on the number of 
commenters who indicated that exposure assessment is not practical in 
construction because of changing tasks and conditions (see summary and 
explanation of Exposure Assessment), OSHA expects most employers to use 
Table 1 for tasks listed on the Table (i.e., most of the tasks that 
generate silica exposure in construction). Under any available exposure 
control method, however, the most convenient way for construction 
employers to determine eligibility for medical surveillance is by 
counting the number of days the employee will be required to wear a 
respirator. Because respirator use is tied with certain tasks in Table 
1, medical surveillance based on respirator use in Table 1 is 
consistent with the task-based approach described by Francisco Trujillo 
above. It is also consistent with the task-based triggers in the 
cadmium construction standard (29 CFR 1926.1127) and operation-based 
triggers (e.g., Class I work) in the asbestos construction standard (29 
CFR 1926.1101).
    OSHA concludes that a trigger based on respirator use will greatly 
simplify determining which employees covered by the construction 
standard must be offered medical surveillance. Consistent with the 
approach described by Kevin Turner above, company personnel on site, 
such as supervisors, could easily record or estimate when employees 
perform, or will perform, tasks requiring respirator use. Such 
information could be conveyed to a company employee who tracks it. 
Despite testifying that he would have a hard time tracking a greater 
number of employees who may require medical surveillance if the PEL or 
action level in effect at that time were lowered, Francisco Trujillo, 
from Miller and Long, a company with approximately 1,500 field 
employees, indicated that his company has a system that monitors and 
sends emails when employees are due for another medical examination 
(Document ID 3585, Tr. 3008-3010). OSHA sees no reason why this system 
could not be applied to larger numbers of employees, and this shows 
that it is possible for large companies to track exposures for numerous 
employees. Tracking exposures or days of respirator use will likely be 
easier for smaller companies who have fewer employees to track; OSHA 
estimates from existing data that approximately 93 percent of 
construction companies covered by the respirable crystalline silica 
standard have fewer than 20 employees (see Chapter III of the FEA). In 
addition, compliance officers would be able to determine if employees 
were exposed for 30 or more days a year but not offered medical 
surveillance by questioning employees about how often they engage in 
tasks that require respirator use for that employer.
    Fann Contracting asked how a trigger for medical surveillance would 
apply to employees, such as heavy machine operators, who may briefly 
use respirators, such as when outside a cab for 30 minutes (Document ID 
2116, Attachment 1, p. 3). OSHA clarifies that if an employee is 
required to wear a respirator at any time during a given day, whether 
to comply with the specified exposure control methods in paragraph (c) 
or to limit exposure to the PEL under the construction standard for 
respirable crystalline silica, that day counts toward the 30-day 
threshold.
    Commenters also questioned the appropriateness of a 30-day 
exposure-duration trigger for construction. For example, American 
Society of Safety Engineers (ASSE) voiced concerns about the standard 
not addressing temporary employees who are continually exposed from job 
to job but may never stay with an employer for a full 30 days (Document 
ID 2339, p. 5). Conversely, CISC questioned why OSHA diverged from the 
ASTM exposure-duration trigger of 120 days, which would reduce the need 
to make medical surveillance available for short-term employees, and 
stated that OSHA needed to explain how this would improve the health of 
employees (Document ID 2319, p. 118; 1504, pp. 4-5). Members of the 
ASTM committee that developed the ASTM E 2625-09 standard testified 
that a 120-day exposure-duration trigger was selected so that employers 
did not have to provide medical surveillance to transient employees and 
that even a trigger of less than 90 days was considered but would have 
resulted in too much pressure and cost for employers because of the 
transient nature of construction work (Document ID 3580, Tr. 1452-1453; 
3585, Tr. 2919-2920).
    OSHA understands that offering medical surveillance for a transient 
workforce may be challenging, especially for small companies. However, 
the requirement to offer periodic medical examinations every three 
years rather than annually will reduce the cost and burden of providing 
such examinations considerably (see Chapter V of the FEA). OSHA finds 
both the 120-day exposure-duration trigger (in the ASTM standards) and 
the 90-day trigger (considered by the ASTM committee) overly exclusive 
and insufficiently protective. Under those longer triggers, many short-
term employees (i.e., those doing tasks requiring respirator use or 
otherwise exposed above the PEL for 30 or more days a year but 
nonetheless exposed for less than 90 days with the same employer) would 
be deprived of the health benefits of medical surveillance, such as 
early detection of disease, despite being at risk due to repeated 
exposures with different employers. As noted above, the health effects 
of respirable crystalline silica are most likely to occur as a result 
of repeated exposures. OSHA concludes that a 30-day exposure-duration 
trigger strikes a reasonable balance between the administrative burden 
of offering medical surveillance to all employees, many of whom may not 
be further exposed or only occasionally exposed, and the need for 
medical surveillance for employees who are regularly exposed and more 
likely to experience adverse health effects. The 30-day

[[Page 16817]]

trigger is also administratively convenient insofar as it is consistent 
with OSHA standards for construction, including asbestos (29 CFR 
1926.1101), cadmium (29 CFR 1926.1127), chromium (VI) (29 CFR 
1926.1126), and lead (29 CFR 1926.62).
    Commenters also raised other issues regarding the 30-day exposure-
duration trigger that could apply to both the general industry and 
maritime standard and the construction standard. One concern was that 
inclusion of a 30-day trigger would result in discriminatory actions by 
employers in order to avoid offering medical surveillance. For example, 
Dr. Daniel Anna, Vice President of AIHA, was concerned that employers 
might refuse to hire someone approaching 30 days of exposure (Document 
ID 3578, Tr. 1048-1049); BAC also expressed concerns about employers 
terminating employees approaching their 30th day of exposure (Document 
ID 4219, p. 29). In addition, BAC noted that employers rotating 
employees to maintain employee exposure below 30 days might result in 
more employees being exposed to silica (Document ID 2329, p. 8).
    Comments indicating that an employer might refuse to hire employees 
approaching their 30th day of exposure are based on an interpretation 
that medical surveillance is triggered by a total of 30 days of 
exposure per year with any employer. Such an interpretation was 
conveyed by the Shipbuilders Council of America and ASSE who commented 
that employers would need to know employee exposures with past 
employers when determining total days of exposure above the PEL 
(Document ID 2255, p. 3; 3578, Tr. 1048). That is not OSHA's intent, 
and OSHA clarifies that exposures occurring with past employers do not 
count towards the 30-day-per-year exposure-duration trigger with the 
current employer (i.e., the trigger is for employment with each 
particular employer). However, the 30-day-per-year exposure-duration 
trigger would apply when an employer hires a particular employee for 
more than one short-term assignment during a year, totaling 30 days or 
more. An advantage of not considering total exposures with all 
employers in triggering medical surveillance is that it avoids creating 
an incentive not to hire. With regard to comments about possible 
discriminatory practices (e.g., termination before the 30th day) or 
rotating employees to avoid medical surveillance, OSHA rejects the 
reasoning that employers will base employment and placement decisions 
on the 30-day exposure-duration trigger because the cost of medical 
examinations is modest (i.e., the FEA estimates the average cost of 
each medical examination at approximately $400 every three years).
    Charles Gordon suggested that employers give each departing 
employee a card indicating the number of days they were exposed above 
the trigger point so that future employers would have a better idea if 
the employee was eligible for another medical examination based on 30 
days of exposure (Document ID 4236, pp. 3-4). Such a record of past 
exposure with any prior employer is not necessary because of OSHA's 
decision to not consider exposures with past employers when triggering 
medical surveillance. Requiring employers to record exposures with past 
employers and to give employees a card indicating the number of days 
they were exposed above the trigger point increases recordkeeping and 
paperwork burdens for employers. It also imposes a burden on employees 
because it gives them an additional document that they need to 
maintain. To avoid these added burdens and for the reasons previously 
given for not counting exposures with other employers towards an 
employee's medical surveillance requirement, OSHA rejects Mr. Gordon's 
suggestion.
    NIOSH and Fann Contracting questioned the 30-day-per-year exposure-
duration trigger because employees who have been exposed to silica for 
years, but are not currently exposed 30 days per year, would be at risk 
of developing lung diseases (Document ID 2116, Attachment 1, p. 41; 
2177, Attachment B, pp. 39-40). NIOSH recommended that medical 
surveillance continue after an employee is no longer exposed to 
respirable crystalline silica but continues to work for the same 
employer (Document ID 2177, Attachment B, p. 39). James Schultz, safety 
director at Navistar Waukesha Foundry and representing the Wisconsin 
Coalition for Occupational Safety and Health (WisCOSH), testified that 
medical surveillance should continue after employees have left ``this 
type of work environment'' (Document ID 3586, Tr. 3200-3201). However, 
NIOSH also stated that considerations for continued medical 
surveillance include the number of years an employee was required to be 
monitored and if the employee is showing signs of silica-related 
illness (Document ID 2177, Attachment B, p. 39).
    OSHA agrees with NIOSH that silica is retained in the lungs and can 
cause progressive damage after exposures end. However, the lack of 
clear criteria in the record for determining when continued medical 
surveillance would be beneficial precludes OSHA from mandating 
continued medical surveillance after exposure ends. In addition, OSHA 
policy is clear that requirements are imposed on current employers. In 
the benzene standard, OSHA articulated that policy in deciding not to 
mandate continued medical surveillance for employees who are no longer 
exposed above the trigger, noting administrative difficulties in 
keeping track of employees who had moved on to other jobs (52 FR 34460, 
34550 (9/11/1987)).
    CISC, American Subcontractors Association, OSCO Industries, and 
Holes Incorporated questioned why medical surveillance is needed for 
younger employees when respirable crystalline silica-related diseases 
take years to develop (Document ID 1992, p. 11; 2187, p. 7; 2319, pp. 
116-117; 3580, Tr. 1471). CISC recommended that OSHA trigger medical 
surveillance after a minimum duration of exposure or when a silica-
related disease is diagnosed. In contrast, Andrew O'Brien, Vice 
President of Safety and Health at Unimin Corporation and representing 
NISA, emphasized the importance of establishing a baseline for future 
measurement (Document ID 3577, Tr. 570). When asked if age or duration 
of exposures should be considered in determining frequency of medical 
surveillance, Dr. Laura Welch, occupational physician with BCTD, 
responded:

. . . we're looking at different disease outcomes. If we were only 
concerned about silicosis, you could probably . . . make that 
argument, but silica exposure also causes [chronic obstructive 
pulmonary disease], and that has an earlier onset and . . . it's 
good to have a baseline of a couple of tests before someone develops 
disease so you can more clearly see an early decline (Document ID 
3581, Tr. 1667).

    When a BAC panel was asked if 20 years after first exposure is the 
appropriate time to start medical surveillance, terrazzo worker Sean 
Barret responded:

    According to their 20-year standard, you wouldn't even find out 
I was sick until next year. I was sick a year ago, and it probably 
showed five years before that. So, I mean, that's ludicrous 
(Document ID 3585, Tr. 3055).

    OSHA agrees that employees' baseline findings are important for 
future diagnoses and notes Dr. Welch's testimony that other silica-
related diseases, such as chronic obstructive pulmonary disease (COPD), 
develop in shorter times than silicosis. Based on such evidence, OSHA 
concludes that it is appropriate to start medical surveillance in young 
or newly exposed

[[Page 16818]]

employees before they experience declines in health or function 
associated with age or respirable crystalline silica exposure.
    Paragraph (i)(1)(ii) of the standard for general industry and 
maritime (paragraph (h)(1)(ii) of the standard for construction) 
requires that the medical examinations made available under the rule be 
performed by a PLHCP, who is defined (see summary and explanation of 
Definitions) as an individual whose legally permitted scope of practice 
(i.e., license, registration, or certification) allows him or her to 
independently provide or be delegated the responsibility to provide 
some or all of the particular health services required by paragraph (i) 
of the standard for general industry and maritime (paragraph (h) of the 
standard for construction). This provision is unchanged from the 
proposed rule.
    The American Public Health Association (APHA) requested changes to 
the definition of PLHCP that would require the PLHCP to be licensed for 
independent practice (Document ID 2178, Attachment 1, p. 5). OSHA finds 
that requested change to be too restrictive. To assure competency while 
providing for increased flexibility, OSHA continues to find it 
appropriate to allow any professional to perform medical examinations 
and procedures made available under the standard when he or she is 
licensed by state law to do so. In this respect, which and how a health 
care professional can function as a PLHCP under the rule may vary from 
state to state depending on each state's licensing requirements and 
laws governing what diagnostic examinations and procedures they are 
permitted to perform. In no case, however, is the authorization in this 
rule to use any PLHCP narrower or stricter than what is authorized in 
the particular state where an examination occurs.
    Some commenters expressed concern about the availability of PLHCPs 
or other medical professionals in certain geographical locations. For 
example, Fann Contracting and the National Rural Electric Cooperative 
Association commented that PLHCPs who can offer the required 
examinations or occupational health resources may not be available for 
employers located in rural areas or near retirement communities 
(Document ID 2116, Attachment 1, p. 43; 2365, p. 10). Under the rule, a 
PLHCP, as defined, does not have to be an occupational medicine 
physician or even a physician to conduct the initial and periodic 
examinations required by the rule, but can be any health care 
professional who is state-licensed to provide or be delegated the 
responsibility to provide those services. The procedures required for 
initial and periodic medical examinations are commonly conducted in the 
general population (i.e., medical history, physical examination, chest 
X-ray, spirometry test, and tuberculosis test) by practitioners with 
varying qualifications. Because medical examinations consist of 
procedures conducted in the general population and because OSHA is 
giving employers maximum flexibility in selecting a PLHCP who can offer 
these services, OSHA intends to assure that employers will not 
experience great difficulty in finding PLHCPs who are state-licensed to 
provide or be delegated the responsibility to provide these services. 
Even in the case of X-rays, OSHA finds that the availability of digital 
X-ray technology allows for electronic submission to a remotely located 
B Reader for interpretation, and thus does not expect a limited number 
of B readers in a certain geographic location to be an obstacle to 
employers covered by the rule.
    Initial examination. Paragraph (i)(2) of the standard for general 
industry and maritime (paragraph (h)(2) of the standard for 
construction) specifies that an initial (baseline) medical examination 
must be made available within 30 days of initial assignment (i.e., the 
day the employee starts working in a job with potential exposures above 
the trigger point), unless the employee received an examination that 
meets the requirements of this section within the past three years. 
This provision is unchanged from the proposed rule. The requirement for 
an initial examination within 30 days of assignment provides a health 
baseline for future reference and lets employees know of any conditions 
that could increase their sensitivity to respirable crystalline silica 
exposure. For example, Dr. Tee Guidotti, an occupational medicine 
physician representing the Association of Occupational and 
Environmental Clinics (AOEC), testified that existing COPD may make an 
individual more sensitive to respirable crystalline silica exposure 
(Document ID 3577, Tr. 797-798).
    Newmont Mining Corporation, Nevada Mining Association, and 
Distribution Contractors Association (DCA) questioned whether recent or 
future exposures should be considered in triggering certain aspects of 
the initial examination (e.g., physical examination, chest X-ray, or 
pulmonary function tests) and indicated that baseline examinations 
should only be required near the time when exposures begin (Document ID 
1963, p. 2; 2107, p. 3; 2309, p. 5). The requirement is for employers 
to offer initial examinations to employees who ``will be'' 
occupationally exposed to respirable silica at or above the action 
level for 30 or more days a year in the standard for general industry 
and maritime (paragraph (i)(1)(i)) or who ``will be'' required to use a 
respirator under this section for 30 or more days per year in the 
standard for construction (paragraph (h)(1)(i)). Therefore, eligibility 
for medical examinations is based on expected exposure with the current 
employer. These triggers apply to both initial and periodic medical 
surveillance, and inclusion of the terms ``will be occupationally 
exposed'' or ``will be required'' makes it clear that requirements to 
offer medical surveillance are not based on past exposures. OSHA is 
aware that unexpected circumstances may result in employees being 
exposed more frequently than initially anticipated. In those cases, 
employers should make medical surveillance available as soon as it 
becomes apparent that the employee will be exposed above the 
appropriate trigger point for 30 or more days per year.
    In the preamble of the Notice of Proposed Rulemaking (NPRM), OSHA 
indicated that where an examination that complies with the requirements 
of the standard has been provided in the past three years, an 
additional initial examination would not be needed (78 FR at 56468). 
Ameren agreed with OSHA's preliminary determination on this issue and 
asked the Agency to verify that examinations conducted in the last 
three years could be supplemented with any additional requirements of 
the rule, such as tuberculosis testing (Document ID 2315, p. 4). OSHA 
agrees that this is a reasonable approach. For example, if an employee 
received an examination that met all the requirements of the initial 
medical examination, with the exception of a tuberculosis test, within 
the last three years, the employer could supplement that examination by 
offering only the tuberculosis test. That same employer or a future 
employer could then offer a periodic medical examination, which does 
not require a tuberculosis test, three years from the last medical 
examination. New hires, who received medical surveillance that met the 
requirements of the respirable crystalline silica rule from a past 
employer, should have a copy of the PLHCP's written medical opinion for 
the employer, which the employer must ensure that the employee receives

[[Page 16819]]

within 30 days of the examination (paragraph (i)(6)(iii) of the 
standard for general industry and maritime, paragraph (h)(6)(iii) of 
the standard for construction), as proof of a current initial or 
periodic medical examination that met the requirements of this section 
(see example of the PLHCP's written medical opinion for the employer in 
Appendix B). If a newly hired employee eligible for medical 
surveillance presents proof of an examination that met the requirements 
of the rule, the employer's obligation is to offer the periodic 
examination required by paragraph (i)(3) of the standard for general 
industry and maritime (paragraph (h)(3) of the standard for 
construction) within three years of the previous examination.
    Commenting on the three year period in which the result of a prior 
examination can substitute for a new initial (baseline) examination, 
APHA, Collegium Ramazzini, and the American Federation of State, County 
and Municipal Employees (AFSCME) opined that three years between 
examinations is an excessive time period because it does not provide 
for an adequate baseline; Collegium Ramazzini further commented that 
medical findings and medical or work histories can change in three 
years and that spirometry performed at other locations does not provide 
an adequate baseline (Document ID 2178, Attachment 1, p. 4; 3541, pp. 
4-5; 4203, p. 6). Dr. Celeste Monforton, from George Washington 
University School of Public Health, agreed with APHA (Document ID 3577, 
Tr. 846). OSHA disagrees. The three-year interval is consistent with 
the frequency of periodic examinations, and the reasons for this 
interval, such as the typical slow progression of respirable 
crystalline silica-related diseases, are discussed below.
    The American Foundry Society (AFS) supported the 30-day period for 
offering medical surveillance, stating that it addressed the turnover 
rates in its industry because employees who work 30 days are likely to 
continue their employment (Document ID 2379, Appendix 1, p. 71). AESC 
requested that OSHA allow medical examinations to be provided within 90 
days of assignment to address the turnover rate in its industry 
(Document ID 2344, p. 2). The National Stone, Sand and Gravel 
Association (NSSGA) noted difficulties in scheduling medical 
examinations within 30 days in remote locations because testing vans 
that offer medical examinations might not be available within that time 
period (Document ID 3583, Tr. 2316-2317). Because a 30-day period for 
offering medical examinations is reasonable for AFS, which represents 
an industry with high turnover rates, OSHA concludes that a 30-day 
period should be reasonable in most general industry settings. OSHA 
does not agree with AESC that the period to offer medical surveillance 
should be extended to 90 days in the standard for general industry and 
maritime. That longer time period to offer medical surveillance would 
exclude and leave unprotected many employees who may be exposed to 
significant amounts of silica while working short-term assignments, for 
periods up to 90 days, for numerous companies within the same industry.
    Representatives from the construction industry also commented on 
the 30-day period to offer medical surveillance. BAC and BCTD 
recommended that medical examinations be made available as soon as 
practicable, instead of within 30 days after assignment, in the 
construction industry because it would be difficult for employers to 
predict if an employee would be exposed for 30 days or more during the 
upcoming year, and it could encourage employers to terminate employees 
before the 30-day period ends (Document ID 4219, p. 29; 4223, p. 125). 
Fann Contracting suggested that a better trigger would be after the 
employee has been exposed for 30 days instead of within the first 30 
days of assignment (Document ID 2116, Attachment 1, p. 43).
    OSHA rejects this reasoning, and is maintaining the requirement to 
offer medical surveillance within 30 days of assignment for the 
construction standard. The requirement better assures that medical 
examinations will be offered within a reasonable time period than 
allowing the employer to offer them ``as soon as practicable.'' As 
noted above, employers can determine who will be eligible for medical 
surveillance based on required respirator use under Table 1 or similar 
task-based approaches. Even at the time of initial assignment, OSHA 
expects that employers will know the tasks that the employee will be 
performing, and in the case of short-term employees, the approximate 
duration the employee will be with the company. In addition, 
terminating employees to avoid offering medical surveillance would not 
be cost effective because the employer would incur more costs from 
constantly having to train new employees.
    The Precast/Prestressed Concrete Institute commented that local 
union halls from which they hire employees and the Americans with 
Disability Act may prohibit pre-hire medical testing (Document ID 2276, 
p. 10). National Electrical Contractors Association expressed concern 
about economic burdens associated with pre- and post-employment medical 
evaluations in transient or temporary employees (Document ID 2295, p. 
2). OSHA clarifies that no pre-hire or post-employment testing is 
required in the respirable crystalline silica rule, which requires that 
medical examinations related to respirable crystalline silica exposure 
be offered within 30 days after initial assignment to employees who 
will meet the trigger for medical surveillance.
    Contents of initial medical examination. Paragraphs (i)(2)(i)-(vi) 
of the standard for general industry and maritime (paragraphs 
(h)(2)(i)-(vi) of the standard for construction) specify that the 
initial medical examination provided by the PLHCP must consist of: A 
medical and work history; a physical examination with special emphasis 
on the respiratory system; a chest X-ray; a pulmonary function test; a 
latent tuberculosis test; and other tests deemed appropriate by the 
PLHCP. Special emphasis must be placed on the portions of the medical 
and work history focusing on exposure to respirable crystalline silica, 
dust or other agents affecting the respiratory system, any history of 
respiratory system dysfunction (including signs and symptoms, such as 
shortness of breath, coughing, and wheezing), any history of 
tuberculosis, and current or past smoking. The only changes from the 
proposed rule are reflected in paragraphs (i)(2)(iii) and (iv) of the 
standard for general industry and maritime (paragraphs (h)(2)(iii) and 
(iv) of the standard for construction), and those revisions are 
discussed below.
    OSHA received a range of comments related to the contents of the 
initial examination. Some stakeholders, including NIOSH and commenters 
representing the medical community, labor unions, and industry, 
supported the contents of medical surveillance that OSHA proposed, 
though some wanted to expand the contents, as addressed below (e.g., 
Document ID 2175, p. 6; 2177, Attachment B, pp. 38-39; 2282, Attachment 
3, p. 19; 2336, p. 12; 2371, Attachment 1, p. 43; 3589, Tr. 4205; 4204, 
p. 82). Further, the contents of medical surveillance in this standard 
are fairly consistent with the recommendations in occupational health 
programs, such as those by NISA and NSSGA (Document ID 2195, pp. 40-41; 
2327, Attachment 1, p. 23).
    However, not all stakeholders agreed that the list of proposed 
initial examination contents was appropriate. For example, Fann 
Contracting favored

[[Page 16820]]

limiting the contents of medical examinations to X-rays, while Dal-Tile 
Corporation, the 3M Company, and the Tile Council of North America 
indicated that requirements for medical examinations under the 
respiratory protection standard were sufficient (Document ID 2116, 
Attachment 1, p. 37; 2147, p. 3; 2313, p. 7; 2363, pp. 5-6). Similarly, 
Nevada Mining Association commented that the need to conduct physical 
examinations, X-rays, or pulmonary function testing should be left to 
the discretion of the PLHCP (Document ID 2107, pp. 3-4). Newmont Mining 
also said that one or more of these tests should be at the discretion 
of the PLHCP (Document ID 1963, pp. 2-3).
    OSHA finds that X-rays alone are not sufficient because, as 
explained in more detail below, some employees may have symptoms or 
abnormal lung function that are not detected by X-ray but may become 
evident by other tests, such as spirometry. The Agency also finds that 
the evaluations offered under the respiratory protection standard are 
insufficient because the information gathered under that standard is 
limited and may not involve examinations, while the respirable 
crystalline silica rule requires examinations that include objective 
measures, such as physical examinations, spirometry testing and X-rays, 
that may detect early disease in asymptomatic employees. In addition, 
OSHA does not agree that all required tests should be left to the 
discretion of the PLHCP because the Agency has determined that 
employees who must be offered medical surveillance are at risk of 
developing respirable crystalline silica-related diseases, and the 
required tests are the minimum tests needed to screen for those 
diseases. Therefore, OSHA concludes that limiting medical surveillance 
to only X-rays, the evaluations performed under the respiratory 
protection standard, or only tests selected by the PLHCP is not 
sufficiently protective.
    The first item required as part of the initial medical examination 
is a medical and work history, with emphasis on: Past, present, and 
anticipated exposure to respirable crystalline silica, dust, and other 
agents affecting the respiratory system; any history of respiratory 
system dysfunction, including signs and symptoms of respiratory disease 
(e.g., shortness of breath, cough, wheezing); history of tuberculosis; 
and smoking status and history (paragraph (i)(2)(i) of the standard for 
general industry and maritime, paragraph (h)(2)(i) of the standard for 
construction). OSHA is requiring medical and work histories because 
they are an efficient and inexpensive means for collecting information 
that can aid in identifying individuals who are at risk due to 
hazardous exposures (Document ID 1505, p. 2; 1517, p. 25). Recording of 
symptoms is important because, in some cases, symptoms indicating onset 
of disease can occur in the absence of abnormal laboratory test 
findings (Document ID 1517, p. 25).
    Because symptoms may be the earliest sign of disease and to allow 
for consistent and comprehensive data collection, Collegium Ramazzini 
recommended that an appendix with a standardized questionnaire be 
included; it also recommended that the questionnaire address non-
respiratory effects, such as renal disease and connective tissue 
disorders (Document ID 3541, pp. 3, 6). While not going as far as this 
recommendation, OSHA includes in the rule an appendix for medical 
surveillance (Appendix B), which gives PLHCPs detailed information on 
what is to be collected as part of the medical history. The appendix 
recommends collecting information on renal disease and connective 
tissue disorders. OSHA intends for this approach to allow PLHCPs to 
easily standardize their method for gathering information for work and 
medical histories related to respirable crystalline silica exposure.
    Newmont Mining and Nevada Mining Association objected to a 
requirement for a medical and work history, asserting that a personal 
medical history is not related to silica exposure (Document ID 1963, p. 
2; 2107, p. 3). Commenters, including DCA and International Brotherhood 
of Teamsters, objected to employees revealing medical and work history 
information not related to respirable crystalline silica exposure 
because of privacy concerns (e.g., Document ID 2309, p. 5; 2318, pp. 
13-14). Retired foundry employee, Allen Schultz, representing WisCOSH, 
expressed concern that information, such as smoking history, could be 
used against employees (Document ID 3586, Tr. 3255). As noted above, a 
purpose of medical surveillance is to inform employees if they may be 
at increased risk of adverse effects from respirable crystalline silica 
exposure. Personal habits, such as smoking, could lead to compromised 
lung function or increased risk of lung cancer, and exposure to 
respirable crystalline silica could compound those effects (see Section 
V, Health Effects). Collecting information, such as smoking habits and 
related medical history, allows the PLHCP to warn employees about their 
increased risks from exposure to respirable crystalline silica so 
employees can make informed health decisions.
    As discussed below, OSHA is addressing employee privacy issues by 
reducing the information to be included in the PLHCP's written medical 
opinion for the employer without the employee's permission (paragraphs 
(i)(6)(i)(A)-(C) of the standard for general industry and maritime and 
paragraphs (h)(6)(i)(A)-(C) of the standard for construction); under 
those paragraphs, the only medically related information that is to be 
reported to the employer without authorization from the employee is 
limitations on respirator use. Personal habits, such as smoking, are 
not included in the medical opinion for the employer. Therefore, 
employees' privacy will not be compromised as a result of the 
information collected as part of the exposure and medical history.
    The second item required as part of the initial medical examination 
is a physical examination that focuses on the respiratory system 
(paragraph (i)(2)(ii) of the standard for general industry and 
maritime, paragraph (h)(2)(ii) of the standard for construction), which 
is known to be susceptible to respirable crystalline silica toxicity. 
OSHA finds that aspects of the physical examination, such as visual 
inspection, palpation, tapping, and listening with a stethoscope, allow 
the PLHCP to detect abnormalities in chest shape or lung sounds that 
are associated with compromised lung function (Document ID 1514, p. 74; 
1517, pp. 26-27). Dr. Michael Fischman, occupational and environmental 
physician/toxicologist and professor at the University of California, 
representing ACOEM, strongly endorsed a physical examination and noted 
that another valuable aspect is that it allows the employee to have a 
face-to-face interaction with the clinician to talk about symptoms or 
other concerns (Document ID 3577, Tr. 767). OSHA agrees and concludes 
that the physical examination is necessary.
    The third item required as part of the initial medical examination 
is a chest X-ray, specifically a single posteroanterior radiographic 
projection or radiograph of the chest at full inspiration recorded on 
either film (no less than 14 x 17 inches and no more than 16 x 17 
inches) or digital radiography systems, interpreted and classified 
according to the International Labour Office (ILO) International 
Classification of Radiographs of Pneumoconioses by a NIOSH-certified B 
Reader (paragraph (i)(2)(iii) of the standard for general industry and 
maritime, paragraph (h)(2)(iii) of the standard for construction). The 
proposed rule

[[Page 16821]]

specified only film X-rays but would have allowed for an equivalent 
diagnostic study, such as digital X-rays; OSHA also sought comment on 
whether computed tomography (CT) or high resolution computed tomography 
(HRCT) scans should be considered equivalent diagnostic tests (78 FR at 
56469-56470). As discussed in greater detail below, OSHA received many 
comments on the proposed provision, and in response to those comments, 
the current provision differs substantially from the proposed rule in 
two main ways. First, the rule now specifically allows for chest X-rays 
to be recorded on either film or digital radiography systems. Second, 
the rule does not allow for an ``equivalent diagnostic study.''
    Medical experts including ACOEM, the American Thoracic Society 
(ATS), and NIOSH recommend X-rays as part of medical examinations for 
employees exposed to respirable crystalline silica (e.g., Document ID 
1505, p. 2; 2175, p. 6; 2177, Attachment B, pp. 38-39). The initial X-
ray provides baseline data against which to assess any subsequent 
changes. An initial chest X-ray can be useful for diagnosing silicosis 
and for detecting mycobacterial disease (e.g., active pulmonary 
tuberculosis, which employees with latent tuberculosis infections and 
exposed to respirable crystalline silica are at greater risk of 
developing (Document ID 1514, pp. 75, 100). X-rays are important 
because the findings can lead to the initiation of employment choices 
that can reduce exposures to respirable crystalline silica and might 
decrease the risk of silicosis progression or allow for treatment of 
mycobacterial infections (Document ID 1505, p. 3).
    As noted above, OSHA proposed that the required chest X-ray be 
interpreted and classified according to ILO International 
Classification of Radiographs of Pneumoconiosis by a NIOSH-certified B 
Reader. The ILO system was designed to assess X-ray and digital 
radiographic image quality and to describe radiographic findings of 
pneumoconiosis in a simple and reproducible way by comparing an 
employee's X-ray to a standard X-ray to score opacities according to 
shape, size, location, and profusion (Document ID 1475, p. 1; 1511, pp. 
64-68; 1514, pp. 77-78). A NIOSH-certified B Reader is a physician who 
has demonstrated competency in the ILO classification system by passing 
proficiency and periodic recertification examinations (Document ID 
1498, p. 1). The NIOSH certification procedures were designed to 
improve the proficiency of X-ray and digital radiographic image readers 
and minimize variability of readings.
    In 2011, the ILO made standard digital radiographic images 
available and published guidelines on the interpretation and 
classification of digital radiographic images (Document ID 1475). The 
guidelines included requirements for display monitors. NIOSH also 
published guidelines for conducting digital radiography and displaying 
digital radiographic images in a manner that will allow for 
classification according to ILO guidelines (Document ID 1513). Based on 
these developments, OSHA stated in the preamble of the NPRM that 
digital X-rays could now be evaluated according to the same guidelines 
as film X-rays and could therefore be considered equivalent diagnostic 
tests. The Agency also noted several advantages of digital X-rays: 
Compared to film X-rays, digital imaging systems offer more consistent 
image quality, faster results, increased ability to share images with 
multiple readers, simplified storage of images, and reduced risk for 
technicians and the environment due to the elimination of chemicals for 
developing film (Document ID 1495, p. 2).
    Commenters, such as Collegium Ramazzini, NIOSH, and the Dow 
Chemical Company, agreed with OSHA that digital radiographic images are 
equivalent to conventional X-rays; NIOSH and Dow Chemical suggested 
OSHA clarify that the proposed requirement for chest X-rays may be 
satisfied either with conventional film-based technology or with 
digital technology; and NIOSH and Collegium Ramazzini referred OSHA to 
an interim final regulation for coal miners that allows for digital 
technology (Document ID 2177, Attachment B, pp. 40-41; 2270, p. 13; 
3541, p. 7). After reviewing the record evidence on this issue, OSHA 
reaffirms its preliminary conclusion that X-rays recorded on digital 
radiography systems are equivalent to those recorded on film. 
Therefore, OSHA has revised paragraph (i)(2)(iii) of the standard for 
general industry and maritime (paragraph (h)(2)(iii) of the standard 
for construction) to indicate that X-rays can be recorded on either 
film or digital systems, using language that is consistent with that in 
the interim final regulation for coal miners (42 CFR part 37.2 (10-1-13 
Edition)).
    NSSGA commented that good quality digital images reproduced on film 
should also be considered acceptable as equivalent to X-rays (Document 
ID 2327, Attachment 1, p. 23). OSHA disagrees. The Agency does not 
recommend classification using hard copies printed from digital images 
because a 2009 study by Franzblau et al. indicates that they give the 
appearance of more opacities compared to films or digital images 
(Document ID 1512). OSHA does not find hard copy printouts of digital 
images equivalent to conventional X-rays. Consequently, classification 
through the use of hard copies printed from digital images may not be 
used to satisfy the requirement for chest X-rays.
    As indicated above, the proposed rule called for the chest X-ray to 
be interpreted and classified by a NIOSH-certified B reader. A number 
of commenters offered opinions on this requirement. For example, Dow 
Chemical urged OSHA to allow board certified radiologists to interpret 
the X-rays because it claimed that insufficient numbers of B Readers 
would lead to a backlog of X-ray interpretation that would make it 
impossible for B Readers to get their reports back to PLHCPs within the 
required 30 days (Document ID 2270, p. 9). Other representatives from 
industry, such as the Mason Contractors Association of America, ARMA, 
and the North American Insulation Manufacturers Association, expressed 
similar concerns about numbers of B Readers (e.g., Document ID 2286, 
pp. 2-3; 2291, p. 26; 2348, Attachment 1, pp. 39-40).
    The rulemaking record contains ample evidence of sufficient numbers 
of B Readers and the value of B Reader interpretation according to ILO 
methods. CISC and NIOSH estimated demands on B Readers based on OSHA's 
estimate in the preamble of the NPRM that 454,000 medical examinations 
would be required in the first year after the rule is promulgated (78 
FR at 56468). Based on the 242 B Readers accounted for as of February 
12, 2013 (78 FR at 56470), CISC estimated 1,876 chest X-rays for each B 
Reader, requiring each B Reader to interpret more than five chest X-
rays per day, which CISC claimed would result in a backlog (Document ID 
2319, p. 118). However, Dr. David Weissman, Director of NIOSH's 
Division of Respiratory Disease Studies, indicated that a B Reader can 
easily classify 10 images in an hour (Document ID 3579, Tr. 196, 
Attachment 2, p. 1). NIOSH estimated that a B Reader working 1 hour per 
day, 5 days per week, 50 weeks per year can classify 2,500 images and 
that 182 B Readers working a minimum of 1 hour per day and 50 weeks per 
year would be needed to classify X-rays for 454,000 employees (Document 
ID 4233, Attachment 1, p. 40). As of May 19, 2014, there were 221 
certified B Readers in the United States, an adequate number to meet 
the demands for the respirable crystalline silica rule (Document ID 
3998, Attachment 15, p.

[[Page 16822]]

2). Based on the new triggers and more recent data on turnover rates, 
OSHA estimates that approximately 520,000 medical examinations will be 
required in the first year after the rule is promulgated. Using Dr. 
Weissman's assumptions, OSHA estimates that 221 B Readers would need to 
spend less than 1 hour a day to classify X-rays for 520,000 employees.
    Dr. Weissman testified that the number of B Readers is driven by 
supply and demand created by a free market and that many physicians 
choose to become B Readers based on demands for such services (Document 
ID 3579, Tr. 197-198, Attachment 2, p. 1). He went on to state that 
NIOSH provides several pathways for physicians to become B Readers, 
such as free self-study materials by mail or download and free B Reader 
examinations. In addition, courses and examinations for certification 
are offered for a fee every three years through the American College of 
Radiology. Dr. Robert Cohen, pulmonary physician and clinical professor 
at the University of Illinois, representing ATS, agreed that NIOSH is 
able to train enough B Readers to handle any potential increase in 
demand (Document ID 3577, Tr. 777). Moreover, even if B Readers are 
scarce in certain geographical locations, digital X-rays can easily be 
transmitted electronically to B Readers located anywhere in the U.S. 
(Document ID 2116, Attachment 1, p. 43; 3580, Tr. 1471-1472; 3585, Tr. 
2887; 2270, p. 13; 2195, p. 44; 3577, Tr. 817-818). Based on this 
information, OSHA concludes that numbers of B Readers in the U.S. are 
adequate to interpret X-rays conducted as part of the respirable 
crystalline silica rule.
    Some commenters questioned the value of requiring B Readers. Dow 
Chemical claimed that board certified radiologists are able to provide 
interpretations of X-rays that are consistent with those of B Readers 
and that such an approach is consistent with that of the OSHA Asbestos 
standard (29 CFR 1910.1001, Appendix E) (Document ID 2270, pp. 9-10). 
Dow Chemical also stated that digital radiography has improved 
interpretation accuracy for radiologists who are not B Readers. 
American Road and Transportation Builders Association (ARTBA) commented 
that inadequate numbers of B Readers could result in misinterpretations 
of X-rays. It also cited a study by Gitlin et al. (2004), which it 
interpreted as showing that B Readers can be biased by exposure 
information; according to ARBTA, the study reported that B Readers 
hired for asbestos litigation cases read 95.9 percent of X-rays as 
positive, while independent, blinded B readers only read 4.5 percent of 
those X-rays as positive (Document ID 2245, pp. 2-3).
    Based on record evidence, OSHA finds that the requirement for B 
Readers to demonstrate proficiency in ILO methods results in more 
consistent X-ray interpretation. For example, guidelines by the World 
Health Organization (WHO) acknowledge the value of consistent, high-
quality X-rays for reducing interpretation variability and note that B 
Reader certification may also improve consistency of X-ray 
interpretation (Document ID 1517, p. 21). Robert Glenn, Certified 
Industrial Hygienist representing the Brick Industry Association and 
previously in charge of the B Reader program at NIOSH, said he thought 
the reduced variability (i.e., lower prevalence of small opacities 
graded 1/0 or greater in unexposed populations) in the U.S. compared to 
Europe in a study by Meyer et al. (1997) could be attributed to the 
success of the B Reader program (Document ID 3577, Tr. 668, 670, 682; 
3419, p. 404). Dr. James Cone, occupational medicine physician at the 
New York City Department of Health, stated that development of ILO 
methods for evaluating pneumoconiosis by chest X-ray has led to greater 
precision and sensitivity. Dr. Cone gave the example that two B Readers 
who evaluated X-rays performed on foundry employees as part of a NIOSH 
Health Hazard Evaluation identified six cases of X-rays and 
occupational history consistent with silicosis that had been classified 
as normal by company physicians (Document ID 2157, pp. 4-5). Based on 
the record evidence demonstrating the value of B Reader certification, 
OSHA rejects the suggestion that the standard should allow X-ray 
interpretation by board-certified radiologists.
    The evidence discussed above supports OSHA's conclusions that 
adequate numbers of B Readers are available locally or by electronic 
means to interpret chest X-rays of respirable crystalline silica-
exposed employees and that B Reader certification improves the quality 
of X-ray interpretation. OSHA concludes that standardized procedures 
for the evaluation of X-ray films and digital images by certified B 
Readers is warranted based on the seriousness of silicosis and is 
therefore retaining that requirement in the rule.
    OSHA noted in the preamble for the NPRM that CT or HRCT scans could 
be considered ``equivalent diagnostic studies.'' CT and HRCT scans are 
superior to chest X-ray in the early detection of silicosis and the 
identification of progressive massive fibrosis. However, CT and HRCT 
scans have risks and disadvantages that include higher radiation doses 
and current unavailability of standardized methods for interpreting and 
reporting the results (78 FR at 56470). Because of these concerns, OSHA 
specifically sought comment on whether CT and HRCT scans should be 
considered equivalent diagnostic studies under the rule, and a number 
of stakeholders provided comments on this issue.
    In its prehearing comments, ATS stated that despite the lack of 
standardized interpretation and reporting methods, CT or HRCT are 
reasonable ``equivalent diagnostic studies'' to standard chest X-rays 
because they are more sensitive than X-rays for early detection of 
diseases, such as silicosis and lung cancer; however, the group's 
representative, Dr. Robert Cohen, later testified that HRCT is not 
ready as a screening technique but is a useful diagnostic tool 
(Document ID 2175, p. 6; 3577, Tr. 825). USW noted that interpretation 
methods are being developed for the evaluation of pneumoconiosis by CT 
scan and suggested approaches for the use of low dose CT (LDCT) scans 
to evaluate silicosis and lung cancer in some employees (Document ID 
4214, pp. 9-12).
    Physicians, such as those representing ACOEM, Collegium Ramazzini, 
and NIOSH, did not consider CT or HRCT to be equivalent diagnostic 
studies because of the lack of a widely-accepted standardized system of 
interpretation, such as the ILO method (e.g., Document ID 2080, pp. 7-
8; 2177, Attachment B, p. 40; 3541, p. 7). In addition, NIOSH, APHA, 
Edison Electric Institute (EEI), Collegium Ramazzini, and ACOEM 
indicated the higher radiation doses received from CT and HRCT scans 
make it inappropriate to consider these methods equivalent to X-rays 
(Document ID 2177, Attachment B, p. 40; 2178, Attachment 1, p. 6; 2357, 
pp. 34-35; 3541, p.7; 3577, Tr. 768).
    NIOSH and Collegium Ramazzini also commented on the increased 
sensitivity of CT scans in detecting abnormalities that require follow-
up, which they cited as another reason why CT scans should not be 
considered equivalent to X-rays (Document ID 2177, Attachment B, p. 40; 
3541, p. 7). NIOSH said the abnormalities can suggest lung cancer, but 
most are found to be ``false positives'' (Document ID 2177, Attachment 
B, p. 40). Detection of abnormalities that might suggest cancer can 
lead to anxiety in patients; it can also lead to follow-up with more 
imaging tests that increase radiation exposures or invasive biopsy 
procedures

[[Page 16823]]

that have a risk of complications (Document ID 2177, Attachment B, p. 
40; 3978, pp. 2423, 2427). Commenters also noted that CT scans cost 
more than X-rays (Document ID 2177, Attachment B, p. 40; 2178, 
Attachment 1, p. 6; 3541, p. 7). In addition, Collegium Ramazzini 
stated that chest X-rays are readily accessible in most cases, but 
availability of CT scanning is more limited, especially in rural areas 
(Document ID 3541, p. 7).
    ACOEM, NIOSH, APHA, NSSGA, EEI, and AFL-CIO stated that CT scans 
are appropriate in some cases, such as a part of follow-up examinations 
or if recommended by the PLHCP (Document ID 2080, p. 8; 2177, 
Attachment B, pp. 40-41; 2178, Attachment 1, p. 6; 2327, Attachment 1, 
p. 26; 2357, pp. 34-35; 4204, p. 82). Dr. David Weissman and Dr. 
Rosemary Sokas, occupational physician from Georgetown University, 
representing APHA, indicated that if an employee happens to have had a 
CT scan that was conducted as part of a clinical workup or diagnosis, 
it should be accepted in place of X-rays (Document ID 3577, Tr. 792; 
3579, Tr. 256).
    After reviewing the record on this issue, OSHA has determined that 
CT or HRCT scans should not be considered ``equivalent diagnostic 
studies'' to conventional film or digital chest X-rays for screening of 
silicosis because of higher radiation exposures, lack of a standardized 
classification system for pneumoconiosis, increased false positive 
findings, higher costs, and limited availability in some areas. OSHA 
also agrees with commenters that CT scans may be useful for follow-up 
purposes, as determined on a case-by-case basis by the PLHCP. For 
example, the PLHCP could request a CT scan to diagnose possible 
abnormalities detected by X-ray or other testing done as part of 
surveillance, and the rule gives the PLHCP this option (paragraph 
(i)(2)(vi) of the standard for general industry and maritime, paragraph 
(h)(2)(vi) of the standard for construction). However OSHA does not 
agree that a CT scan conducted within the past three years can meet the 
requirement for an X-ray because the CT scan cannot be evaluated 
according to ILO methods.
    OSHA also received comments on the use of CT scans to screen for 
lung cancer, and those comments are discussed below, as part of the 
Agency's discussion of additional tests that commenters proposed for 
inclusion in medical examinations.
    In sum, unlike the proposed rule, paragraph (i)(2)(iii) of the 
standard for general industry and maritime (paragraph (h)(2)(iii) of 
the standard for construction) specifically allows for digital X-rays, 
but does not allow for an equivalent diagnostic study. The rule was 
revised to allow for digital radiography because OSHA determined that 
digital X-rays are equivalent to film X-rays. The rule was also revised 
to remove the allowance for equivalent diagnostic studies because OSHA 
determined that CT scans are not equivalent to X-rays for screening 
purposes and no other imaging tests are equivalent to film or digital 
X-rays interpreted by ILO methods at this time. The provision for X-
rays does not contain any other substantive changes compared to the 
proposed provision.
    The fourth item required as part of the initial medical examination 
is a pulmonary function test, including forced vital capacity (FVC), 
forced expiratory volume in one second (FEV1), and 
FEV1/FVC ratio, administered by a spirometry technician with 
a current certificate from a NIOSH-approved spirometry course 
(paragraph (i)(2)(iv) of the standard for general industry and 
maritime, paragraph (h)(2)(iv) of the standard for construction). FVC 
is the total volume of air exhaled after a full inspiration, 
FEV1 is the volume of air exhaled in the first second, and 
the FEV1/FVC ratio is the speed of expired air (Document ID 
3630, p. 2). OSHA proposed the inclusion of pulmonary function testing 
(i.e., spirometry, as required by this rule) because it is useful for 
obtaining information about the employee's lung capacity and expiratory 
flow rate and for determining baseline lung function status against 
which to assess any subsequent lung function changes.
    Some industry representatives, such as Fann Contracting and CISC, 
opposed the requirement for spirometry testing because reduced 
pulmonary function can be related to smoking or exposures other than 
respirable crystalline silica (Document ID 2116, Attachment 1, Page 39; 
2319, pp. 118-119). CISC further commented that OSHA did not address 
statements in the ASTM standard about the non-specificity of lung 
function changes to respirable crystalline silica exposure, and a lack 
of evidence that routine spirometry is useful for detecting respirable 
crystalline silica-related diseases in early stages.
    In contrast, commenters, such as Collegium Ramazzini and NIOSH, 
noted that spirometry is useful for detecting lung function changes 
associated with COPD, a disease outcome related to respirable 
crystalline silica exposure (Document ID 3541, p. 8; 3579, Tr. 255). 
ACOEM and Collegium Ramazzini explained that respirable crystalline 
silica exposures can result in lung function changes in the absence of 
radiological abnormalities, and spirometry is important for detecting 
those changes in the early stages of disease; ACOEM further commented 
that early detection of abnormal lung function is important to fully 
assess employees' health and apply protective intervention methods 
(Document ID 2080, p. 8; 3541, p. 8).
    ASSE and some industry representatives, including Newmont Mining, 
NISA and AFS, also supported spirometry testing (e.g., Document ID 
1963, pp. 2-3; 2339, p. 9; 2379, Appendix 1, p. 70; 4208, p. 22). NISA 
includes spirometry testing as part of its occupational health program 
for respirable crystalline silica-exposed employees; it emphasized that 
spirometry testing: (1) Allows for early detection and measurement of 
severity of lung function loss, the most direct symptom of silicosis or 
other nonmalignant respiratory disease, and (2) is useful for 
determining an employee's ability to safely wear a negative pressure 
respirator (Document ID 4208, p. 22).
    After reviewing the comments submitted, OSHA reaffirms that 
spirometry testing should be included in the rule. OSHA concludes that 
even though declines in lung function may not always be related to 
respirable crystalline silica exposure, the test results are 
nonetheless useful for detecting lung function abnormalities that can 
worsen with further exposure to respirable crystalline silica, 
providing a baseline of lung function status against which to assess 
any subsequent changes, and assessing the health of employees who wear 
respirators. The requirement for lung function testing is also 
consistent with other OSHA standards, such as asbestos (29 CFR 
1910.1001) and cadmium (29 CFR 1910.1027). Thus, OSHA decided to retain 
the proposed requirement for a pulmonary function test in the rule.
    OSHA proposed that spirometry be administered by a spirometry 
technician with current certification from a NIOSH-approved spirometry 
course. NIOSH recommended changing ``current certification'' to ``a 
current certificate'' to clarify that NIOSH does not certify individual 
technicians (Document ID 2177, Attachment B, p. 43). OSHA agrees with 
NIOSH that the change provides clarity, without modifying the original 
meaning of the provision, and thus made the change to the proposed 
provision.
    Some stakeholders questioned whether a certificate from a NIOSH-
approved course should be required. For

[[Page 16824]]

example, Dow Chemical recommended that OSHA follow the asbestos 
standard and allow for spirometry testing to be conducted by a person 
who has completed ``a training course in spirometry sponsored by an 
appropriate academic or professional institution'' (29 CFR 
1910.1001(l)(1)(ii)(B)) (Document ID 2270, pp. 11-12). However, other 
stakeholders, including NIOSH and commenters from the medical community 
and labor unions, agreed that the standard should require a current 
certificate from a NIOSH-approved course (Document ID 2157, p. 6; 2177, 
Attachment B, pp. 38-39, 43; 3541, p. 10; 3577, Tr. 777; 4223, pp. 129-
130). Dr. Robert Cohen stated:

. . . spirometry performed by certified NIOSH technicians would be 
very important. We don't want garbage spirometry that we see out in 
the industry all the time. We want real, not what I call cosmetic or 
ceremonial spirometry (Document ID 3577, Tr. 777).

    Dr. James Cone noted an example in which a NIOSH Health Hazard 
Evaluation at a foundry found that the company had recorded abnormal 
pulmonary function test results for 43 employees; however, spirometry 
testing later conducted by NIOSH found that only 9 of those same 
employees had abnormal pulmonary function results. Dr. Cone thought 
that the difference in findings most likely resulted from differences 
in equipment and test procedures used to motivate and elicit 
cooperation of employees during testing (Document ID 2157, pp. 4-5). He 
concluded:

    The difference does suggest that proper equipment, certification 
and training of pulmonary technicians, and standardized reading of 
pulmonary function tests are important to maintain uniformity and 
comparability of such tests (Document ID 2157, p. 5).

    Some commenters, including Collegium Ramazzini, suggested other 
ways that the rule for respirable crystalline silica could improve 
quality of spirometry results. It recommended that the rule specify 
spirometry conducted according to ATS/European Respiratory Society 
(ERS) or similar guidelines, that spirometers meet ATS/ERS 
recommendations, and that the third National Health and Nutrition 
Examination Survey (NHANES III) reference values be used for 
interpretation of results (Document ID 3541, pp. 8-10). Collegium 
Ramazzini emphasized that quality spirometry results depend on 
standardized equipment, test performance, and interpretation of 
results, including criteria, such as acceptability and reproducibility 
of results (Document ID 3541, p. 8). Labor unions, such as LHSFNA and 
BCTD, also supported more stringent spirometry requirements (Document 
ID 3589, Tr. 4205; 4223, pp. 129-130). ACOEM, NIOSH, and BCTD 
recommended that reference values or other spirometry guidelines be 
added to the appendix on medical surveillance (Document ID 2080, p. 9; 
2177, Attachment B, pp. 45-46; 4223, pp. 128-129).
    After considering the record to determine what the rule must 
include to improve spirometry quality, OSHA concludes that requiring 
technicians to have a current certificate from a NIOSH-approved 
spirometry course is essential for maintaining and improving spirometry 
quality. The purpose of requiring spirometry technicians to have a 
current certificate from a NIOSH-approved spirometry course is to 
improve their proficiency in generating quality results that are 
interpreted in a standardized way. OSHA included the certification 
requirement in the proposed rule because spirometry must be conducted 
according to strict standards for quality control and results must be 
consistently interpreted. The NIOSH-approved spirometry training is 
based upon procedures and interpretation standards developed by the 
ATS/ERS and addresses factors, such as instrument calibration, testing 
performance, data quality, and interpretation of results (Document ID 
3625, pp. 2-3).
    NIOSH approves a spirometry training course if it meets the minimum 
OSHA/NIOSH criteria for performance of spirometry testing in the cotton 
textile industry. Since these course criteria are based on 
recommendations from ATS/ERS, they are applicable to spirometry testing 
in all industries. The curriculum of NIOSH-approved courses encompasses 
ATS/ERS recommendations on instrument accuracy (e.g., calibration 
checks); test performance (e.g., coaching, recognizing improperly 
performed maneuvers), and data quality with emphasis on repeatability 
and interpretation of results. Students taking the course use actual 
equipment, while supervised, and are evaluated on their spirometry 
testing skills (Document ID 3625, pp. 2-3). NIOSH periodically audits 
spirometry course sponsors who provide the courses (see http://www.cdc.gov/niosh/topics/spirometry/sponsor-renewal-dates.html). 
Therefore, based on the evidence in the record for this rulemaking, 
OSHA concludes that completing a NIOSH-certified course will make 
spirometry technicians knowledgeable about various issues that 
commenters raised regarding spirometry quality, and has determined that 
the best way to ensure that spirometry technicians receive the level of 
quality training approved by NIOSH is to require a certificate from a 
NIOSH-approved course.
    In considering the alternative suggestions, OSHA concludes that 
requiring a current certificate from a NIOSH-approved course is a 
better approach than mandating requirements for equipment, testing 
procedures, reference values, and interpretation of results, which 
could become outdated. OSHA fully expects that the NIOSH-approved 
initial and periodic refresher courses required to maintain a current 
certificate under this rule will ensure that technicians keep up-to-
date on the most recent ATS/ERS recommendations on spirometry equipment 
and procedures as technology and methods evolve over time.
    In addition, OSHA agrees with commenters that the NHANES III 
reference values should be used to interpret spirometry results because 
they are the most widely endorsed for use in the U.S. (Document ID 
3630, p. 28-29). In cross-sectional testing to evaluate lung function 
at a single point in time, spirometry results are compared to reference 
values (i.e., spirometry values for individuals of the same gender, 
age, height, and ethnicity as the employee being tested). Although 
agreeing with commenters on the value of spirometry testing and use of 
the NHANES III data set for cross-sectional testing, OSHA disagrees 
with commenters that procedures for conducting spirometry and NHANES 
III reference values should be included as part of an appendix. As 
stated above, OSHA's approach to improving spirometry quality is to 
require technicians to have a current certificate from a NIOSH-approved 
course. Describing procedures in an appendix is not necessary because 
spirometry guidance documents, including a comprehensive guidance 
document from OSHA, are widely available. The OSHA spirometry guidance 
is available from the OSHA Web site and lists the NHANES III values in 
an appendix. OSHA encourages individuals who conduct or interpret 
spirometry to review the OSHA guidance on spirometry, which is based on 
recommendations by ATS/ERS, ACOEM, and NIOSH (Document ID 3630; 3624; 
3629; 3631; 3633; 3634).
    OSHA received one comment regarding the practicality of requiring a 
current certificate from a NIOSH-approved course. Dow Chemical claimed 
that availability of NIOSH-approved courses may be limited

[[Page 16825]]

outside of metropolitan areas (Document ID 2270, p. 11). However, 
NIOSH's Web site indicates that course sponsors are located throughout 
the U.S. and that some sponsors will travel to a requested site to 
teach a course (Document ID 3625, p. 3). Moreover, Dow Chemical also 
reported that it and another local company had teamed up to bring in an 
instructor to teach a NIOSH-approved course in their geographical area 
(Document ID 2270, p. 11). OSHA expects that this is a cost-effective 
means of providing NIOSH-approved training in places where none 
currently exists and can be replicated by other spirometry providers 
that provide services to companies covered by this rule. Maintaining a 
certificate from a NIOSH-approved course currently requires initial 
training and then refresher training every five years (Document ID 
3625, p. 1). Because courses appear to be widely available throughout 
the U.S. and the required training is infrequent, OSHA concludes that 
the requirement for a technician to maintain a certificate from a 
NIOSH-approved course will not impose substantial burdens on providers 
of spirometry testing.
    The fifth item required as part of the initial medical examination 
is a test for latent tuberculosis infection (paragraph (i)(2)(v) of the 
standard for general industry and maritime, paragraph (h)(2)(v) of the 
standard for construction). This provision is unchanged from the 
proposed rule. ``Latent'' refers to a stage of infection that does not 
result in symptoms or possible transmission of the disease to others. 
OSHA proposed the inclusion of a test for latent tuberculosis infection 
because exposure to respirable crystalline silica increases the risk of 
a latent tuberculosis infection becoming active (i.e., the infected 
person shows signs and symptoms and is contagious), even in employees 
who do not have silicosis (see Section VI, Final Quantitative Risk 
Assessment and Significance of Risk) (Document ID 0360; 0465; 0992, 
p.1461-1462). This places not only the employee, but also his or her 
coworkers, at increased risk of acquiring this potentially fatal 
disease.
    OSHA sought comment on its preliminary determination that all 
employees receiving an initial medical examination should be tested for 
latent tuberculosis infection. A number of stakeholders, including Dr. 
James Cone, ATS, NIOSH, APHA, NISA, NSSGA, ASSE, BCTD, and ACOEM agreed 
with OSHA's preliminary conclusion that testing for latent tuberculosis 
infection should be part of the initial examination (e.g., Document ID 
2157, p. 6; 2175, p. 6; 2177, Attachment B, pp. 38-39; 2178, Attachment 
1, p. 5; 2195, p. 41; 2327, Attachment 1, p. 23; 2339, p. 9; 2371, 
Attachment 1, p. 43). However, other stakeholders, such as Newmont 
Mining, Nevada Mining Association, and EEI, recommended that testing 
for latent tuberculosis infection be limited to employees who have 
silicosis (e.g., Document ID 1963, p. 2; 2107, p. 3; 2357, p. 34). EEI 
specifically opposed testing for latent tuberculosis infection in the 
absence of radiological evidence of silicosis, arguing that there are 
no good methods for quantifying the benefits of that testing.
    After reviewing the comments on this issue, OSHA affirms its 
conclusion that testing for latent tuberculosis infections is a 
necessary and important part of the initial examination. As noted 
above, evidence demonstrates that exposure to respirable crystalline 
silica increases the risk for developing active pulmonary tuberculosis 
infection in individuals with latent tuberculosis infection, 
independent of the presence of silicosis (Document ID 0360; 0465; 0992, 
pp. 1461-1462). Active tuberculosis cases are prevented by identifying 
and treating those with latent tuberculosis infections. Therefore, OSHA 
concludes it is appropriate to test for latent tuberculosis infection 
in all employees who will be exposed to respirable crystalline silica 
and are eligible for medical surveillance, for their protection and to 
prevent transmission of an active, potentially fatal infection to their 
coworkers. Any concerns about a lack of good methods for calculating 
benefits associated with latent tuberculosis infection testing do not 
negate the scientific evidence demonstrating that exposure to 
respirable crystalline silica increases the risk of a latent infection 
becoming active.
    Newmont Mining, Nevada Mining Association, and Fann Contracting did 
not support testing for latent tuberculosis infection because employees 
with the infection may not have contracted it in an occupational 
setting (Document ID 1963, p. 2; 2107, p. 3; 2116, Attachment 1, p. 
38). While that may be true, testing for latent tuberculosis infection 
provides another example and support for two of the main objectives of 
medical surveillance: (1) To identify conditions that might make 
employees more sensitive to respirable crystalline silica exposure; and 
(2) to allow for intervention methods to prevent development of serious 
disease. Employees with latent tuberculosis infections are at greater 
risk of developing active disease with exposure to respirable 
crystalline silica, and informing them that they have a latent 
infection allows for intervention in the form of treatment to eliminate 
the infection. Treating latent tuberculosis disease before it becomes 
active and can be transmitted to coworkers (and others) is in the best 
interest of both the employer and the affected employee.
    Dr. James Cone and APHA have stated that a positive boosted or 
initial test for tuberculosis infection warrants medical referral for 
further evaluation (Document ID 2157, p. 6; 2178, Attachment 1, p. 5). 
Ameren commented that a positive tuberculosis test warrants medical 
removal (Document ID 2315, p. 9). OSHA agrees that employees who test 
positive for active tuberculosis should be referred to their local 
public health departments as required by state public health law 
(Document ID 2177, Attachment B, p. 50). Those employees will need 
treatment and, if necessary, to be quarantined until they are no longer 
contagious. That is the appropriate action for employees with active 
tuberculosis to prevent infection of coworkers and others, according to 
procedures established by state public health laws. In the case of 
latent tuberculosis, the PLHCP may refer the employee to the local 
public health department, where the employee may get recommendations or 
prescriptions for treatment. Removal is not necessary for latent 
tuberculosis infections because employees with latent tuberculosis 
infections are not contagious. More information about testing for 
latent tuberculosis infections is included in Appendix B.
    The sixth and final item required as part of the initial medical 
examination is any other test deemed appropriate by the PLHCP 
(paragraph (i)(2)(vi) of the standard for general industry and 
maritime, paragraph (h)(2)(vi) of the standard for construction). This 
provision, which is unchanged from the proposed rule, gives the 
examining PLHCP the flexibility to determine additional tests deemed to 
be appropriate. While the tests conducted under this section are for 
screening purposes, diagnostic tests may be necessary to address a 
specific medical complaint or finding related to respirable crystalline 
silica exposure (Document ID 1511, p. 61). For example, the PLHCP may 
decide that additional tests are needed to address abnormal findings in 
a pulmonary function test. OSHA considers the PLHCP to be in the best 
position to decide if any additional medical tests are necessary for 
each individual examined. Under this provision, if a PLHCP decides 
another

[[Page 16826]]

test related to respirable crystalline silica exposure is medically 
indicated, the employer must make it available. EEI commented that OSHA 
should clarify that additional tests must be related to occupational 
exposure to respirable crystalline silica (Document ID 2357, p. 35). 
OSHA agrees and intends the phrase ``deemed appropriate'' to mean that 
additional tests requested by the PLHCP must be both related to 
respirable crystalline silica exposure and medically necessary, based 
on the findings of the medical examination.
    Finally, some stakeholders suggested additional tests to be 
included as part of medical examinations. OSHA did not propose a 
requirement for the initial examination to include a CT scan to screen 
for lung cancer, but a number of commenters thought the rule should 
contain such a requirement. UAW requested that OSHA consider LDCT 
scanning for lung cancer, with guidance from NIOSH and other medical 
experts (Document ID 2282, Attachment 3, pp. 19-20). Charles Gordon 
asked Dr. David Weissman if OSHA should consider CT scans for lung 
cancer screening of silica-exposed employees, as has been recently 
recommended by the U.S. Preventive Service Task Force (USPSTF) for 
persons at high risk of lung cancer. Dr. Weissman responded:

    Well, the recommendation that you're referring to related to 
very heavy cigarette smokers, people who are age 55 to 80, had a 
history of smoking I believe at least 30 pack-years and had smoked 
as recently as 15 years ago. That group has a very, very high risk 
of lung cancer, and as of this time, there are no recommendations 
that parallel that for occupational carcinogens (Document ID 3579, 
Tr. 159-160, Attachment 2, p. 2).

    Collegium Ramazzini and USW asked OSHA to consider various 
scenarios for LDCT lung cancer screening of employees exposed to 
respirable crystalline silica; the different scenarios considered age 
(as a proxy for latency), smoking history, and other risk factors, such 
as non-malignant respiratory disease (Document ID 4196, pp. 5-6; 4214, 
pp. 10-12). Both groups recommended screening in non-smokers, and 
Collegium Ramazzini also recommended screening in employees less than 
50 years of age; both groups cited National Comprehensive Cancer 
Network (NCCN) guidelines as a basis for one or more recommendations, 
and Collegium Ramazzini also cited the American Association for 
Thoracic Surgery (AATS) guidelines. The Communication Workers of 
America (CWA) requested LDCT scans every three years for silica-exposed 
employees over 50 years of age (Document ID 2240, p. 3). Consistent 
with one scenario presented by USW, AFL-CIO requested that OSHA require 
LDCT scans if recommended by the PLHCP or specialist, and AFL-CIO also 
requested that OSHA include a provision (for employees exposed to 
respirable crystalline silica) to allow for regular LDCT scans if 
recommended by an authoritative group (Document ID 4204, p. 82). Dr. 
Rosemary Sokas and Dr. James Melius, occupational physician/
epidemiologist for LHSFNA, requested that OSHA reserve the right to 
allow for adoption of LDCT scans (Document ID 3577, Tr. 793; 3589, Tr. 
4205-4206). Dr. Sokas went on to say that OSHA should start convening 
agencies and organizations to look at levels of risk that warrant LDCT 
(Document ID 3577, Tr. 793).
    In addition to the issues that Dr. Weissman testified about 
regarding the USPSTF recommendations, OSHA notes that the USPSTF 
recommendations are based on modeling studies to determine optimum ages 
and frequency for screening and the scenarios in which benefits of LDCT 
screening (e.g., increased survival) would outweigh harms (e.g., cancer 
risk from radiation exposure). The screening scenario recommended by 
USPSTF (55- to 80-year-olds with a 30-pack-year smoking history who 
have not quit more than 15 years ago) is estimated to result in a 14 
percent decrease in lung cancer deaths, with a less than 1 percent risk 
for radiation-related lung cancer (Document ID 3965, p. 337). USPSTF 
stresses that LDCT screening should be limited to high-risk persons 
because persons at lower risk are expected to experience fewer benefits 
and more harm; they cautioned that starting LDCT screening before age 
50 might result in increased rates of radiation-related lung cancer 
deaths (Document ID 3965, p. 336). USPSTF also warns about the high 
rate of false positive findings with LDCT, which often lead to more 
radiation exposure through additional imaging tests and can result in 
invasive procedures, which have their own risks, to rule out cancer. It 
cautions that lower rates of lung cancer mortality from LDCT screening 
are most likely to be found at institutions demonstrating accurate 
diagnoses, appropriate follow-up procedures for abnormal findings, and 
clear standards for performing invasive procedures (Document ID 3965, 
pp. 333, 336).
    Both NCCN and AATS guidelines recommend screening scenarios that 
are similar to the USPSTF guideline (e.g., 55 or more years of age and 
at least a 30-pack-year history) (Document ID as cited in 3965, p. 338; 
3976, p. 33). NCCN and AATS guidelines also recommend screening for 50-
year-olds or older, who have a 20-pack-year or more smoking history and 
an additional risk factor. AATS specifies that the additional risk 
factor should result in a cumulative lung cancer risk of at least 5 
percent in the next 5 years, and they identify additional risk factors, 
such as COPD, with an FEV1 of 70 percent or less of 
predicted value, and environmental or occupational exposures, including 
silica (Document ID 3976, pp. 33, 35-37). Neither the NCCN nor AATS 
guideline recommend screening for individuals younger than 50 years of 
age or nonsmokers, and neither NCCN nor AATS indicates that its 
guidelines are based on risk-benefit analyses.
    OSHA agrees that employees exposed to respirable crystalline silica 
are at increased risk of developing lung cancer, as addressed in 
Section V, Health Effects. However, OSHA has two major concerns that 
preclude the Agency from requiring LDCT screening for lung cancer under 
the respirable crystalline silica rule. The first concern is that 
availability of LDCT is likely to be limited. Few institutions that 
offer LDCT have the specialization to effectively conduct screening for 
lung cancer. The second major concern is the lack of a risk-benefit 
analysis. There is no evidence in the rulemaking record showing that 
the benefits of lung cancer screening using LDCT in respirable 
crystalline silica-exposed employees outweigh the risks of lung cancer 
from radiation exposure. OSHA has also not identified authoritative 
recommendations based on risk-benefit analyses for LDCT scanning for 
lung cancer in persons who do not smoke or are less than 50 years of 
age. OSHA concludes that without authoritative risk-benefit analyses, 
the record does not support mandating LDCT screening for respirable 
crystalline silica-exposed employees.
    Periodic examinations. In paragraph (i)(3) of the standard for 
general industry and maritime (paragraph (h)(3) of the standard for 
construction), OSHA requires periodic examinations that include all of 
the items required by the initial examination, except for testing for 
latent tuberculosis infection, i.e., a medical and work history, a 
physical examination emphasizing the respiratory system, chest X-rays, 
pulmonary function tests, and other tests deemed to be appropriate by 
the PLHCP. Employers must offer these examinations every three years, 
or more frequently if recommended by the PLHCP. The frequency of 
periodic

[[Page 16827]]

examinations and their requirements is unchanged from the proposed 
rule.
    Some commenters disagreed with the proposed three-year interval for 
periodic medical examinations. WisCOSH and Charles Gordon thought that 
medical examinations should be offered more often than every three 
years (Document ID 3586, Tr. 3200-3201; 2163, Attachment 1, p. 14). 
Other commenters, including AFSCME and some employee health advocates 
and labor unions, requested that one or more components of medical 
examinations be offered annually (Document ID 1960; 2208; 2240, p. 3; 
2351, p. 15; 4203, p. 6). Collegium Ramazzini recommended annual 
medical surveillance consisting of medical and work history and 
spirometry testing to better characterize symptoms, changes in health 
and work history that could be forgotten, and lung function changes 
(Document ID 3541, p. 12). CISC stated that OSHA did not explain why it 
found an examination every three years necessary and appropriate 
(Document ID 2319, p. 119).
    ATS, NIOSH, USW, and AFS supported the three-year frequency 
requirement for medical surveillance (Document ID 2175, p. 6; 2177, 
Attachment B, pp. 38-39; 2336, p. 11; 2379, Appendix 1, p. 70). NSSGA, 
however, recommended examinations every three to five years (Document 
ID 2327, Attachment 1, p. 24). Although WHO guidelines recommend an 
annual history and spirometry test, the guidelines state that if that 
is not possible, those examinations can be conducted at the same 
frequency they recommend for X-rays (every 2-to-5 years) (Document ID 
1517, p. 32). In support of triennial medical examinations, ATS 
commented that an examination provided every three years is appropriate 
to address a lung disease that typically has a long latency period 
(Document ID 2175, p. 6).
    ACOEM agreed with a frequency of every three years for a medical 
examination, provided that a second baseline examination (excluding X-
rays) is conducted at 18 months following the initial baseline 
examination; this approach was recommended to detect possible symptoms 
of acute silicosis and to more effectively establish a spirometry 
baseline since rapid declines in lung function can occur in dusty work 
environments (Document ID 2080, pp. 5-6). Dr. Celeste Monforton agreed 
with a follow-up examination at 18 months (Document ID 3577, Tr. 846).
    APHA, AFL-CIO, BAC, and BCTD also agreed with ACOEM's suggestion 
for a follow-up examination within 18-months, adding that a three-year 
interval between examinations is acceptable if medical examinations are 
offered to employees experiencing signs and symptoms related to 
respirable crystalline silica exposure (Document ID 2178, Attachment 1, 
pp. 4-5; 4204, pp. 81-82; 4219, pp. 30-31; 4223, pp. 127-128). 
BlueGreen Alliance, UAW, Center for Effective Government (CEG), CPR, 
WisCOSH, and AFSCME also requested that medical surveillance be offered 
for employees experiencing symptoms (Document ID 2176, p. 2; 2282, 
Attachment 3, pp. 22-23; 2341, pp. 2-3; 2351, p. 15, Fn 29; 3586, Tr. 
3200-3201; 4203, p. 6). The AFL-CIO and UAW stated that a symptom 
trigger is appropriate based on the high level of risk remaining at 
OSHA's proposed action level and PEL (Document ID 2282, Attachment 3, 
p. 22; 4204, p. 81). APHA, CEG, and BCTD also argued that employees 
should be allowed to see a PLHCP if they are concerned about excessive 
exposure levels or their ability to use a respirator (Document ID 2178, 
p. 5: 2341, pp. 2-3; 4223, pp. 127-128).
    After considering all comments on this issue, OSHA concludes that 
the record supports requiring periodic examinations to be offered to 
employees at least every three years after the initial (baseline) or 
most recent periodic medical examination for employees who are eligible 
for initial and continued medical surveillance under the rule. 
Accordingly, paragraph (i)(3) of the standard for general industry and 
maritime (paragraph (h)(3) of the standard for construction) requires 
periodic examinations at least every three years, or more frequently if 
recommended by the PLHCP. One of the main goals of periodic medical 
surveillance for employees exposed to respirable crystalline silica is 
to detect adverse health effects, such as silicosis and other non-
malignant lung diseases, at an early stage so that medical and other 
appropriate interventions can be taken to improve health. Consistent 
with the NIOSH and ATS comments, OSHA finds that medical examinations 
offered at a frequency of at least every three years is appropriate for 
most employees exposed to respirable crystalline silica in light of the 
slow progression of most silica-related diseases. This decision is also 
consistent with ASTM standards E 1132-06 and E 2625-09 (Section 4.6.5), 
which recommend that medical surveillance be conducted no less than 
every three years (Document ID 1466, p. 5; 1504, p. 5).
    OSHA declines to adopt ACOEM's recommendation for a second baseline 
examination at 18 months. As noted above, this request was based upon 
detection of possible acute silicosis symptoms. Considering that acute 
silicosis and the rapid declines in lung function associated with it, 
as a result of extremely high exposures, are rare, OSHA determines that 
this extra examination would not benefit the vast majority of employees 
exposed to respirable crystalline silica. However, as noted above, 
paragraph (i)(3) of the standard for general industry and maritime 
(paragraph (h)(3) of the standard for construction) authorizes the 
PLHCP to recommend, and requires the employer to make available, 
increased frequency of medical surveillance. OSHA agrees with Dr. James 
Melius that more frequent medical examinations are appropriate if 
requested by the PLHCP based on abnormal findings or signs of possible 
illness, and the Agency agrees with ACOEM that the PLHCP may recommend 
more frequent medical surveillance based on an exposure history 
indicating unknown or high exposure to respirable crystalline silica 
(Document ID 2080, p. 6; 3589, Tr. 4203). OSHA concludes that allowing 
the PLHCP to determine when increased frequency of medical examinations 
is needed is a better approach than requiring all employees to receive 
annual medical examinations or a second baseline examination at 18 
months.
    OSHA did not include a symptom trigger because symptoms of silica-
related lung diseases (e.g., cough, shortness of breath, and wheeze) 
are very common and non-specific, unlike symptoms resulting from 
exposures to some other chemicals OSHA has regulated. In addition, 
based on the employee health privacy concerns expressed in this 
rulemaking (discussed below), OSHA does not expect many employees to 
ask their employer for a medical examination when they experience 
symptoms. Furthermore, employees who are the most likely to develop 
symptoms are those exposed above the PEL. Those employees, who would be 
required to wear respirators, and also construction employees required 
to wear respirators under Table 1, are entitled to an additional 
medical evaluation under the respiratory protection standard if they 
report signs or symptoms that are related to ability to use a 
respirator (29 CFR 1910.134(e)(7)(i)). Therefore, employees at the 
highest risk of developing symptoms will be able to take advantage of 
that provision in the respiratory protection standard.
    AIHA recommended that OSHA consider decreased frequency of testing 
in employees with less than 10 to 15 years of experience because of the 
small chance of finding disease, and it noted

[[Page 16828]]

that this was done in the asbestos standard (29 CFR 1910.1001, 
1926.1101) (Document ID 2169, p. 6). Medical surveillance guidelines 
from ACOEM, Industrial Minerals Association (IMA)/Mine Safety and 
Health Administration (MSHA) and NISA recommend periodic medical 
examinations at intervals from two to four years (with the exception of 
a follow-up examination in some cases), depending on age, years since 
first exposure, exposure levels, or symptoms (Document ID 1505, pp. 3-
4; 1511, pp. 78-79; 1514, pp. 109-110). As noted by the IMA/MSHA 
guidelines, a compromise schedule that is easier to administer is 
acceptable if it is difficult to offer surveillance based on multiple 
considerations (Document ID 1511, pp. 78-79). OSHA agrees with the IMA/
MSHA approach of choosing a schedule that is easy to administer. The 
Agency concludes that surveillance every three years is an 
administratively convenient frequency that strikes a reasonable balance 
between the resources required to provide surveillance and the need to 
diagnose health effects at an early stage to allow for interventions.
    In addition to the above general comments as to the appropriate 
frequency of periodic examinations, some stakeholders offered comments 
on particular components of periodic examinations, in particular chest 
X-rays and pulmonary function tests. As noted above, chest X-rays are 
included in the periodic, as well as initial (baseline), medical 
examinations. Periodic chest X-rays are appropriate tools for detecting 
and monitoring the progression of silicosis and possible complications, 
such as mycobacterial disease, including tuberculosis infection 
(Document ID 1505, p. 3; 1511, pp. 63, 79). Safety professional Albert 
Condello III stated that X-rays should be offered annually (Document ID 
1960). OSHA concludes that every three years is an appropriate interval 
for X-ray examinations. The frequency is within ranges recommended by 
ACOEM, IMA/MSHA, NISA, and WHO (Document ID 1505, pp. 3-4; 1511 pp. 78-
79; 1514, pp. 109-110; 1517, p. 32). Commenters representing NIOSH, the 
medical community, and industry agreed that a frequency of every three 
years is appropriate for X-rays (Document ID 2157, p. 6; 2177, 
Attachment B, pp. 38-39; 2315, p. 9; 2327, Attachment 1, p. 25; 2379, 
Appendix 1, p. 70; 3541, p. 5).
    OSHA also received comments on the inclusion of pulmonary function 
(i.e., spirometry) tests in periodic examinations and the appropriate 
frequency for such tests. As noted under the discussion of tests 
included as part of the initial medical evaluation, some commenters 
questioned whether spirometry in general should be required for 
employees exposed to respirable crystalline silica. For the same reason 
that OSHA decided to include spirometry as a required element in the 
initial medical examination, it concludes that requiring spirometry as 
part of the periodic examination is appropriate; that reason is that a 
spirometry test is a valuable tool for detecting possible lung function 
abnormalities associated with respirable crystalline silica-related 
disease and for monitoring the health of exposed employees. Spirometry 
tests that adhere to strict quality standards and that are administered 
by a technician who has a current certificate showing successful 
completion of a NIOSH-approved spirometry course, are useful for 
monitoring progressive lung function changes in individual employees 
and in groups of employees.
    The proposed interval of three years for spirometry testing was an 
issue in the rulemaking. OSHA proposed this interval because exposure 
to respirable crystalline silica does not usually cause severe declines 
in lung function over short time periods. Spirometry testing conducted 
every three years is within ranges of recommended frequencies, based on 
factors such as age and exposure duration or intensity, in guidelines 
by ACOEM and BCTD, although ACOEM and BCTD recommend an evaluation at 
18 months following the baseline test (Document ID 1505, p. 3; 1509, p. 
15; 2080, pp. 5-6; 4223, p. 128). Guidelines from WHO recommend yearly 
spirometry tests, but indicate that if that is not possible, spirometry 
can be conducted at the same frequency as X-rays (every 2-to-5 years) 
(Document ID 1517, p. 32).
    OSHA specifically requested comment on the appropriate frequency of 
lung function testing, which it proposed at intervals of every three 
years. ASSE agreed that spirometry testing every three years is 
consistent with most credible occupational health programs for 
respirable crystalline silica exposure (Document ID 2339, p. 9). 
Industry stakeholders, such as Ameren, NSSGA, and AFS, also supported 
conducting spirometry testing every three years (Document ID 2315, p. 
9; 2327, Attachment 1, pp. 24-25; 2379, Appendix 1, p. 70).
    Collegium Ramazzini stated that spirometry testing should be 
conducted annually rather than triennially (Document ID 3541, pp. 12-
13). In support of its statement, Collegium Ramazzini interpreted data 
from a Wang and Petsonk (2004) study to mean that an FEV1 
loss of 990 milliliters (mL) or higher could occur before detection of 
lung function loss with testing every three years (Document ID 3541, 
pp. 12-13; 3636).
    The Wang and Petsonk 2004 study was designed to measure lung 
function changes in coal miners over 6- to 12-month intervals. The 
study authors reported that in the group of coal miners studied, a 
year-to-year decline in lung function (i.e., FEV1) of 8 
percent or 330 mL or more, based on the 5th percentile, should not be 
considered normal (i.e., the results did not likely occur by chance in 
healthy males). To understand the implications of this finding, OSHA 
consulted 2014 ATS guidelines. Those guidelines urge caution in 
interpreting early lung function changes in miners because early, rapid 
declines in lung function are often temporary and might occur because 
of inflammation. They further indicate that estimates of lung function 
decline are more precise as the length of follow-up increases and that 
real declines in lung function become easier to distinguish from 
background variability. In addition, ATS cautions that short-term 
losses in lung function can be difficult to evaluate because of 
variability (Document ID 3632, pp. 988-989).
    OSHA notes that, in fact, Figure 1 of the Wang and Petsonk study 
shows that lung function loss measured over a 5-year period in that 
cohort of miners is much less variable than changes measured over 6- to 
12-month intervals. OSHA therefore finds that this study indicates that 
long-term measurements in lung function are more reliable for assessing 
the level of lung function decline over time. Based on Table 1 of the 
Wang and Petsonk study, mean annual FEV1 loss, when 
evaluated over a 5-year period, was 36 and 56 mL/year in stable and 
healthy miners, respectively. Even among rapid decliners evaluated over 
five years, mean decline in FEV1 was 122 mL/year. Unlike 
Collegium Ramazzini, OSHA does not interpret the Wang and Petsonk study 
to mean that an FEV1 loss of 990 mL or higher could occur 
before detection of lung function loss with testing every three years 
The study authors themselves conclude:

    However, even among workers in our study who met this >8% or 
>330 mL criterion, many did not show accelerated declines over the 
entire 5 years of follow up (data not shown), emphasizing that a 
finding of an increased year-to-year decline in an individual 
requires further assessment and confirmation (Document ID 3636, p. 
595).

    In sum, OSHA finds that the Wang and Petsonk study is not a basis 
for concluding that triennial spirometry

[[Page 16829]]

testing is inadequate for assessing lung function loss in most 
employees exposed to respirable crystalline silica.
    Collegium Ramazzini also cited a 2012 Hnizdo study that 
demonstrated greater stability and predictability for excessive loss of 
lung function with more frequent testing. In that study, spirometry 
data were useful for predicting decline only after the fourth or fifth 
year of follow-up; Collegium Ramazzini stated that only two spirometry 
tests would be available in six years if employees are tested every 
three years (Document ID 3541, p. 13; 3627, p. 1506). OSHA notes that 
three spirometry reports would be available following six years of 
triennial testing (the initial examination, the three-year examination, 
and the six-year examination). In addition, Hnizdo concluded that 
annual spirometry was best, but even in employees tested every three 
years, useful clinical data were generated with five to six years of 
follow-up (Document ID 3627, p. 1511).
    The ATS committee also reviewed the Hnizdo study and concluded that 
precision in determining rate of FEV1 decline improves with 
greater frequency of measurement and duration of follow-up. Because 
chronic diseases, such as COPD and pneumoconiosis, typically develop 
over a span of years, the ATS committee concluded that spirometry 
performed every two-to-three years should be sufficient to monitor the 
development of such diseases (Document ID 3632, p. 988). NIOSH Division 
of Respiratory Disease Studies Director, Dr. David Weissman, who was on 
the ATS committee, also agreed that spirometry testing every three 
years is appropriate for respirable crystalline silica-exposed 
employees (Document ID 3632, p. 1; 3579, Tr. 255).
    After consideration of the rulemaking evidence on this issue, OSHA 
concludes that spirometry testing every three years is appropriate to 
monitor employees' lung function and that the frequency is well 
supported in the record. Therefore, consistent with its proposed rule, 
OSHA is including a frequency of at least every three years for 
spirometry testing.
    As discussed above in connection with the initial testing 
requirement, spirometry usually involves cross-sectional testing for 
assessing lung function at a single time point. Longitudinal spirometry 
testing that compares employees' lung function to their baseline levels 
is also useful for detecting excessive declines in lung function that 
could lead to severe impairment over time. OSHA did not propose a 
requirement to assess longitudinal changes in lung function. Commenters 
including Collegium Ramazzini, LHSFNA, and BCTD requested that the 
standard include requirements or instructions for longitudinal testing 
to compare an employee's current lung function value to his or her 
baseline value (Document ID 3541, p. 10; 3589, Tr. 4205; 4223, p. 129). 
As noted by Dr. L. Christine Oliver, associate clinical professor of 
medicine at Harvard Medical School, representing Collegium Ramazzini:

    Excessive loss of lung function may indicate early development 
of silica-related disease, even in the absence of an abnormal test 
result. So spirometry at one point in time may be normal, but 
compared to the baseline of that individual, there may have been a 
decline. So even though the test result itself is normal, it doesn't 
mean that there is not something going on with regard to that 
individual's lung function (Document ID 3588; Tr. 3855).

    Both Collegium Ramazzini and BCTD requested that the standard 
require referral to a specialist for excessive losses of pulmonary 
function. Collegium Ramazzini recommended specialist referral for a 
year-to-year decline in FEV1 of greater than 8 percent or 
330 mL based on the study by Wang and Petsonk discussed above (Document 
ID 3541, pp. 3, 9-10; 3636). BCTD recommended specialist referral for a 
year-to-year decline in FEV1 of greater than 10 percent 
based on ACOEM guidance (Document ID 4223, p. 129; 3634, pp. 579-580).
    OSHA endorses in principle the value of longitudinal spirometry 
analyses to compare employees' lung function to their baseline values, 
but is not adopting the specific recommendation to incorporate it into 
the rule. Based on a review of the available evidence, OSHA is 
concerned about several challenges in determining an employee's change 
from baseline values, which preclude the Agency from requiring 
longitudinal analyses with an across-the-board trigger of 8-to-10 
percent loss of baseline lung function for specialist referral. First, 
a lung function loss of 8-to-10 percent is more stringent than general 
recommendations from ACOEM and ATS. OSHA notes that the complete ACOEM 
recommendation for evaluating longitudinal changes in lung function 
states:

    When high-quality spirometry testing is in place, ACOEM 
continues to recommend medical referral for workers whose 
FEV1 losses exceed 15%, after allowing for the expected 
loss due to aging. Smaller declines of 10% to 15%, after allowing 
for the expected loss due to aging, may be important when the 
relationship between longitudinal results and the endpoint disease 
is clear. These smaller declines must first be confirmed, and then, 
if the technical quality of the pulmonary function measurement is 
adequate, acted upon (Document ID 3634, p. 580).

    The ACOEM recommendation is based on ATS guidelines indicating that 
year-to-year changes in lung function exceeding 15 percent are probably 
unusual in healthy individuals. A recent ATS committee restated that 
position:

    ATS recommends that a decline of 15% or more over a year in 
otherwise healthy individuals be called ``significant,'' beyond what 
would be expected from typical variability (Document ID 3632, p. 
989).

    As ATS indicated, actual lung function losses must be distinguished 
from measurement variability. Variability in spirometry findings can 
occur as a result of technical factors (e.g., testing procedures, 
technician competence, and variations in equipment) and biological 
factors related to employees being tested (e.g., circadian rhythms, 
illness, or recovery from surgery) (Document ID 3630, p. 32). The 
requirement for testing by a technician with a current certificate from 
a NIOSH-approved course improves spirometry quality and reduces 
variability related to testing technique and technician competence. 
However, OSHA is aware that even with high quality spirometry programs, 
variability in results can still occur from factors such as changes in 
equipment and/or testing protocol.
    Collegium Ramazzini noted that spirometry performed at a location 
other than that of the first employer may not provide an adequate 
baseline to evaluate lung function changes in the absence of quality 
control and standardized equipment, methodology, and interpretation 
(Document ID 3541, p. 5). OSHA is concerned about the ability to 
differentiate lung function changes from variability, even with 
standardization and quality control. ACOEM has concluded that frequent 
changing of spirometry providers may prevent a meaningful evaluation of 
longitudinal testing results (Document ID 3633, p. 1309). OSHA 
recognizes that changes in spirometry providers could preclude 
evaluating changes in lung function from baseline values and that 
employees in high-turnover industries, e.g., construction, could be 
particularly affected if they undergo spirometry testing on different 
types of spirometers used by different providers contracted by the 
different employers for whom they work.
    In addressing the issue of construction employees frequently 
changing employers, Dr. L. Christine Oliver recommended storing 
spirometry results in a central database or providing them to employees 
to allow

[[Page 16830]]

comparison of current results with past results (Document ID 3588, Tr. 
3873-3875). As indicated above, technical quality of past spirometry 
should be evaluated before examining longitudinal change in lung 
function. Full spirometry reports should be examined for indicators of 
test quality (e.g., acceptability and repeatability of spirometry 
maneuvers). OSHA encourages PLHCPs to give employees copies of their 
full medical records, including spirometry reports with numerical 
values and graphical illustrations of expiratory curves. Employees 
(including former employees) also have a right to access their medical 
records under OSHA's access to medical and exposure records rule (29 
CFR 1910.1020). Presenting past spirometry records to a new PLHCP might 
allow for the interpretation of lung function compared to baseline 
values, but the PLHCP would have to determine if this evaluation is 
possible based on spirometry technical quality.
    In sum, OSHA recognizes the value of longitudinal analyses that 
compare an individual's lung function to their baseline values. Recent 
studies have shown that excessive decline in lung function can be an 
early warning sign for risk of COPD development (Document ID 1516). 
Therefore, identifying employees who are at risk of developing severe 
decrements in lung function can allow for interventions to possibly 
prevent or slow progression of disease and thus justifies periodic 
spirometry. But because of the complexities and challenges described 
above, OSHA is not mandating testing to compare employees' lung 
function values to baseline values or specifying a lung function loss 
trigger for referral to a specialist. OSHA concludes that spirometry 
conducted every three years is appropriate to detect the possible 
development of lung function impairment. However, the PLHCP is in the 
best position to determine how spirometry results should be evaluated. 
Under paragraph (i)(5)(iv) of the standard for general industry and 
maritime (paragraph (h)(5)(iv) of the standard for construction), 
PLHCPs have the authority to recommend referral to a specialist if 
``otherwise deemed appropriate,'' and an informed judgment or suspicion 
that excessive lung function loss or an actual lung function 
abnormality has occurred would be an appropriate reason for referral to 
a specialist with the necessary skills and capability to make that 
evaluation.
    Information provided to the PLHCP. Paragraph (i)(4)(i)-(iv) of the 
standard for general industry and maritime (paragraph (h)(4)(i)-(iv) of 
the standard for construction) requires the employer to ensure that the 
examining PLHCP has a copy of the standard, and to provide the 
following information to the PLHCP: A description of the employee's 
former, current, and anticipated duties as they relate to respirable 
crystalline silica exposure; the employee's former, current, and 
anticipated exposure levels; a description of any personal protective 
equipment (PPE) used, or to be used, by the employee, including when 
and for how long the employee has used or will use that equipment; and 
information from records of employment-related medical examinations 
previously provided to the employee and currently within the control of 
the employer. OSHA determined that the PLHCP needs this information to 
evaluate the employee's health in relation to assigned duties and 
fitness to use PPE.
    Some of these provisions reflect minor edits from the proposed 
rule. In paragraphs (i)(4)(i) and (iv) of the standard for general 
industry and maritime (paragraphs (h)(4)(i) and (iv) of the standard 
for construction), OSHA changed ``affected employee'' to ``employee.'' 
OSHA removed the word ``affected'' because it is clear that the 
provisions refer to employees who will be undergoing medical 
examinations. In paragraph (i)(4)(iii) of the standard for general 
industry and maritime (paragraph (h)(4)(iii) of the standard for 
construction), OSHA changed ``has used the equipment'' to ``has used or 
will use the equipment'' to make it consistent with the earlier part of 
the provision that states ``personal protective equipment used or to be 
used.'' These non-substantive changes simply remove superfluous 
language or clarify OSHA's intent, which has not changed from the 
proposed rule.
    OSHA received few comments regarding information to be supplied to 
the PLHCP. NAHB was concerned about obtaining or verifying information, 
such as PPE use, exposure information, and medical information, from 
past employers to give to the PLHCP (Document ID 2296, p. 31). 
Paragraph (i)(4)(iv) of the standard for general industry and maritime 
(paragraph (h)(4)(iv) of the standard for construction) is explicit, 
however, that employers must only provide the information within their 
control. Employers are not expected to provide information to PLHCPs on 
exposures experienced by employees while the employees were working for 
prior employers. Similarly, OSHA intends that where the employer does 
not have information on the employee's past or current exposure level, 
such as when a construction employer uses Table 1 in lieu of exposure 
monitoring, providing the PLHCP with an indication of the exposure 
associated with the task (e.g., likely to be above the PEL) fulfills 
the requirement.
    OSHA identifies the information that the employer must provide to 
the PLHCP, along with information collected as part of the exposure and 
work history, as relevant to the purposes of medical surveillance under 
the rule because it can assist the PLHCP in determining if symptoms or 
a health finding may be related to respirable crystalline silica 
exposure or if the employee might be particularly sensitive to such 
exposure. For example, a finding of abnormal lung function caused by 
asthma might indicate increased sensitivity to a workplace exposure. 
The information will also aid the PLHCP's evaluation of the employee's 
health in relation to recommended limitations on the employee's use of 
respirators or exposure to respirable crystalline silica. For these 
reasons, OSHA is retaining the proposed provisions detailing 
information to be provided to the PLHCP in the rule.
    Written medical reports and opinions. The proposed rule provided 
for the PLHCP to give a written medical opinion to the employer, but 
relied on the employer to give the employee a copy of that opinion; 
thus, there was no difference between information the employer and 
employee received. The rule differentiates the types of information the 
employer and employee receive by including two separate paragraphs 
within the medical surveillance section that require a written medical 
report to go to the employee, and a more limited written medical 
opinion to go to the employer. The former requirement is in paragraph 
(i)(5) of the standard for general industry and maritime (paragraph 
(h)(5) of the standard for construction); the latter requirement is in 
paragraph (i)(6) of the standard for general industry and maritime 
(paragraph (h)(6) of the standard for construction). This summary and 
explanation for those paragraphs first discusses the proposed 
requirements and general comments received in response to the proposed 
requirements. OSHA then explains in this subsection of the preamble its 
decision in response to these comments to change from the proposed 
requirement for a single opinion to go to both the employee and 
employer and replace it with two separate and distinct requirements: 
(1) A full report of medical findings, recommended limitations on 
respirator use or exposure

[[Page 16831]]

to respirable crystalline silica, and any referral for specialist 
examination directly to the employee; and (2) an opinion focused 
primarily on any recommended limitations on respirator use, and with 
the employee's consent, recommended limitations on the employee's 
exposure to respirable crystalline silica and referral to a specialist. 
The ensuing two subsections will then discuss the specific requirements 
and the record comments and testimony relating to those specific 
requirements.
    OSHA proposed that the employer obtain from the PLHCP a written 
medical opinion containing: (1) A description of the employee's health 
condition as it relates to exposure to respirable crystalline silica, 
including any conditions that would put the employee at increased risk 
of material impairment of health from further exposure to respirable 
crystalline silica; (2) recommended limitations on the employee's 
exposure to respirable crystalline silica or use of PPE, such as 
respirators; (3) a statement that the employee should be examined by a 
pulmonary disease specialist if the X-ray is classified as 1/0 or 
higher by the B reader, or if referral to a pulmonary disease 
specialist is otherwise deemed appropriate by the PLHCP; and (4) a 
statement that the PLHCP explained to the employee the medical 
examination results, including conditions related to respirable 
crystalline silica exposure that require further evaluation or 
treatment and any recommendations related to use of protective clothing 
or equipment. The proposed rule would also have required the employer 
to ensure that the PLHCP did not include findings unrelated to 
respirable crystalline silica exposure in the written medical opinion 
provided to the employer or otherwise reveal such findings to the 
employer. OSHA raised the contents of the PLHCP's written medical 
opinion, including privacy concerns, as an issue in the preamble of the 
NPRM in Question 71 in the ``Issues'' section (78 FR at 56290).
    OSHA received a number of comments on these provisions. The 
majority of these comments related to the proposed contents of the 
PLHCP's written medical opinion and its transmission to the employer. 
For example, Dr. Laura Welch expressed concern that the provision that 
would have required the PLHCP to disclose ``a medical condition that 
puts him or her at risk of material impairment to health from exposure 
to silica'' could be read to require disclosure of the employee's 
medical diagnosis (Document ID 3581, Tr. 1580). Dr. Steven Markowitz, 
physician and director of the Center for Biology of Natural Systems at 
Queens College, representing USW, explained:

    So, for example, if I were the examining healthcare provider and 
I saw an employee, and he had what I identified as idiopathic 
pulmonary fibrosis, which is diffuse scarring of the lungs with an 
unknown cause, in this case, not silica, is that information that I 
would need to turn over to the employer because further exposure to 
silica might impair that person's health or not? Or what if the 
worker has emphysema, which is a silica-related condition, and the 
provider believes that that emphysema is not due to silica exposure 
but to the employee's long-time smoking history. Is that information 
that the healthcare provider is supposed to turn over to the 
employer? It isn't at all clear (Document ID 3584, Tr. 2518-2519).

    Some commenters offered suggestions to address privacy concerns 
regarding the content of the proposed PLHCP's written medical opinion 
for the employer and the proposed requirement that the opinion be given 
to the employer instead of the employee. One suggestion advocated by 
UAW, LHSFNA, AFSCME, AFL-CIO, and BCTD was for OSHA to use a model 
based on the black lung rule for coal miners (Document ID 2282, 
Attachment 3, pp. 20-21; 3589, Tr. 4207; 4203, p. 6; 4204, p. 88; 4223, 
p. 134). Under the coal miner regulations, miners receive the medical 
information and employers are prohibited from requiring that 
information from miners (30 CFR 90.3). Commenters including BlueGreen 
Alliance, CWA, USW, and Collegium Ramazzini also urged OSHA to require 
that findings from medical surveillance only be given to employers upon 
authorization by the employee (Document ID 2176, p. 2; 2240, pp. 3-4; 
2336, p. 12; 3541, p. 13). UAW, AFL-CIO, and BCTD referred OSHA to 
ACOEM's recommendations for workplace confidentiality of medical 
information (Document ID 2282, Attachment 3, p. 20; 3578, Tr. 929; 
3581, Tr. 1579-1580). The ACOEM guidelines state:

    Physicians should disclose their professional opinion to both 
the employer and the employee when the employee has undergone a 
medical assessment for fitness to perform a specific job. However, 
the physician should not provide the employer with specific medical 
details or diagnoses unless the employee has given his or her 
permission (Document ID 3622, p. 2).

Exceptions to this recommendation listed under the ACOEM guidelines 
include health and safety concerns. Collegium Ramazzini, BCTD, USW, and 
BAC argued that providing an employer with information about an 
employee's health status violates an employee's privacy and is not 
consistent with societal views reflected in laws, such as the Health 
Insurance Portability and Accountability Act (HIPAA) (Document ID 3541, 
p. 13; 3581, Tr. 1578-1579; 3584, Tr. 2519; 4219, p. 31).
    Although HIPAA regulations allow medical providers to provide 
medical information to employers for the purpose of complying with OSHA 
standards (Document ID 4214, p. 7), OSHA has accounted for stakeholder 
privacy concerns in devising the medical disclosure requirements in the 
rule. OSHA understands that the need to inform employers about a 
PLHCP's recommendations on work limitations associated with an 
employee's exposure to respirable crystalline silica must be balanced 
against the employee's privacy interests. As discussed in further 
detail below, OSHA finds it appropriate to distinguish between the 
PLHCP's recommendations and the underlying medical reasons for those 
recommendations. In doing so, OSHA intends for the PLHCP to limit 
disclosure to the employer to what the employer needs to know to 
protect the employee, which does not include an employee's diagnosis. 
Contrary to some of the comments, it was not OSHA's intent, either in 
the proposed rule or in earlier standards that require information on 
an employee's medical or health condition, to transmit diagnostic 
information to the employer; OSHA intended for the PLHCP merely to 
convey whether or not the employee is at increased risk from exposure 
to respirable crystalline silica (or other workplace hazards in other 
standards) based on any medical condition, whether caused by such 
exposure or not. In re-evaluating how to express this intent, however, 
OSHA concludes that the employer primarily needs to know about any 
recommended limitations without conveying the medical reasons for the 
limitations. Thus, in response to the weight of opinion in this 
rulemaking record and to evolving notions about where the balance 
between preventive health policy and patient privacy is properly 
struck, OSHA is taking a more privacy- and consent-based approach 
regarding the contents of the PLHCP's written medical opinion for the 
employer compared to the proposed requirements and earlier OSHA 
standards. These changes, which are reflected in paragraph (i)(6) of 
the standard for general industry and maritime (paragraph (h)(6) of the 
standard for construction), and the comments that led to these changes, 
are more fully discussed below.
    Reinforcing the privacy concerns, various stakeholders, including 
labor unions, physicians, and employees,

[[Page 16832]]

were also concerned that employees' current or future employment might 
be jeopardized if medical information is reported to employers (e.g., 
Document ID 2282, Attachment 3, p. 20; 3581, Tr. 1582; 3583, Tr. 2470-
2471; 3585, Tr. 3053-3054; 3586, Tr. 3245; 3589, Tr. 4227-4228, 4294-
4295; 4203, pp. 6-7; 4214, pp. 7-8). The same concerns were expressed 
by Sarah Coyne, a painter and Health and Safety Director from the 
International Union of Painters and Allied Trades, who testified that 
many of her fellow union members who have silicosis refused to testify 
at the silica hearings because they feared they would lose their jobs 
if their employers found out they were ill (Document ID 3581, Tr. 1613-
14). Dr. L. Christine Oliver testified that her patients do not want 
medical information reported to employers, and Dr. James Melius stated 
that LHSFNA members are leery of medical surveillance because they fear 
losing their jobs (Document ID 3588, Tr. 3881-3882; 3589, Tr. 4228). 
Deven Johnson, cement mason, described employees hiding injuries from 
supervisors on jobsites for fear of being blacklisted, and said that:

    The same is true with occupational illnesses, that the last 
thing that a worker wants is to have any information that he's 
somehow compromised because, even though we want to think the best 
of the employer, that somebody wouldn't take action against that 
individual, we know for a fact that it happens. It's happened to our 
membership (Document ID 3581, Tr. 1656).

    Industry representatives indirectly confirmed that discrimination 
based on medical results was possible. For example, CISC noted that 
some employers might refuse to hire an employee with silicosis because 
they might have to offer workers' compensation or be held liable if the 
disease progresses (Document ID 4217, pp. 22-23).
    Evidence in the record demonstrates that a likely outcome of 
employees' reluctance to let employers know about their health status 
is refusal to participate in medical surveillance. For example, Dr. 
Rosemary Sokas stated that employees who lack job security would likely 
avoid medical surveillance if the employer receives the results 
(Document ID 3577, Tr. 819-820). In discussing the Coal Workers' Health 
Surveillance Program, Dr. David Weissman stated that maintaining 
confidentiality is critical because:

    One of the biggest reasons in focus groups that miners have 
given for not participating in surveillance is fear of their medical 
information being shared without their permission (Document ID 3579, 
Tr. 169).

    When asked if employees would participate in medical surveillance 
that lacked both employee confidentiality and anti-retaliation and 
discrimination protection, employees Sarah Coyne, Deven Johnson, and 
Dale McNabb stated that they would not (Document ID 3581, Tr. 1657; 
3585, Tr. 3053-3054). BAC and BCTD emphasized that employees must 
choose to participate in medical surveillance in order for it to be 
successful (Document ID 4219, p. 31; 4223, p. 131).
    Industry groups, such as OSCO Industries and NAHB, commented that 
they or employers from their member companies are reluctant to handle 
or maintain confidential medical information (Document ID 1992, p. 12; 
2296, p. 32). NAHB indicated:

    Members have expressed strong concerns that much of [the medical 
information], if not all, would be covered by privacy laws and 
should be between a doctor and patient. . . . Moreover, the PLHCP 
should provide a copy of the written medical opinion to the employee 
directly, not the employer, once it is written (Document ID 2296, 
pp. 31-32).

    However, other industry groups asserted that employers should 
receive detailed information from medical surveillance. In particular, 
NISA argued that reporting medical surveillance findings to employers 
would facilitate epidemiological studies to better understand hazards 
and the effectiveness of a new standard (Document ID 4208, p. 14).
    OSHA agrees that epidemiology studies are important; indeed its 
health effects and significant risk findings in this rule are 
overwhelmingly based on epidemiological studies. However, as noted 
above, it was never OSHA's intent for the PLHCP's written medical 
opinion on respirable crystalline silica to contain specific diagnoses 
or detailed findings that might be useful for an epidemiology study. As 
noted in the summary and explanation of Recordkeeping, OSHA's access to 
employee exposure and medical records standard (29 CFR 1910.1020) 
requires employers to ensure that most employee medical records are 
retained for the duration of employment plus 30 years for employees 
employed more than one year. Such records obtained through appropriate 
legal means, and with personal identifying information omitted or 
masked, would be a possible avenue for conducting epidemiology studies.
    CISC also noted that in past standards, the purpose of medical 
surveillance was to improve health practices by allowing employers to 
understand effects of hazards and, therefore, make changes to the 
worksite, such as implementing controls or removing employees from 
exposure (Document ID 4217, p. 24). Attorney Brad Hammock, representing 
CISC at the public hearing, stated that if OSHA expects employers to 
make placement decisions based on health outcomes and exposure, then 
there would be some value in an employer receiving the PLHCP's opinion. 
However, Mr. Hammock further explained that if the purpose of 
surveillance is simply to educate employees about their health 
situation, then there would be arguably little value in the employer 
receiving the opinion (Document ID 3580, Tr. 1466-1467). Other 
commenters, including ACOEM, AOEC, and NISA, also noted the importance 
of medical surveillance for identifying adverse health effects among 
employees in order to make workplace changes or evaluate the 
effectiveness of regulations or workplace programs (Document ID 2080, 
pp. 9-10; 3577, Tr. 784; 4208, pp. 13, 16-17). Andrew O'Brien testified 
that if employers are not allowed to see medical findings, the first 
time they are made aware of a problem is when they receive a letter 
from the compensation system. Mr. O'Brien stated:

    Without access to that data, you can't . . . potentially see 
disease beginning and take preventative action to prevent it from 
actually having a negative health effect (Document ID 3577, Tr. 
614).

    In contrast to those views, USW questioned the value in providing 
employers with the PHLCP's medical opinion. It stated:

    Exactly what corrections in the workplace will the employer make 
based on newfound knowledge that one of his workers has a silica-
related condition? Silicosis occurs 15 or more years following onset 
of exposure, so that today's silicosis is due to exposure that 
likely occurred decades ago. (Exceptions are acute and accelerated 
silicosis, which are rare and are not expected to occur at the 
recommended PEL.) What inference is the employer supposed to make 
about the magnitude or effect of current exposures under these 
circumstances? Indeed, to make sense of the issue, the employer 
would have to know about the worker's prior silica exposures, quite 
often at different workplaces. But the employer and, quite likely, 
even the worker are unlikely to have high quality data on exposures 
to silica that occurred decades ago. In the absence of such 
information, it is unclear how an employer can properly interpret 
current exposures as causing silicosis. By contrast, the best 
information on current exposures derives from current exposure 
monitoring, and the notion that documenting silicosis can somehow 
provide useful information about current exposures above and beyond 
what proper exposure monitoring is ill-conceived (Document ID 4214, 
p. 8).


[[Page 16833]]


Similarly, Peg Seminario, Director of Safety and Health with AFL-CIO, 
testified that employers should be basing their decisions on exposure 
levels and how well controls are working (Document ID 3578, Tr. 1008). 
NAHB and CISC questioned how an employer should respond if an employee 
has signs of lung disease and the employer has already implemented 
engineering controls and respirator use (Document ID 2296, p. 31; 2319, 
p. 117).
    OSHA agrees that because of the long latency period of most 
respirable crystalline silica-related diseases, a diagnosis of such an 
illness in an employee will not provide useful information about 
current controls or exposure conditions. Employers should be basing 
their actions on exposure assessments and ensuring properly functioning 
controls, such as those listed and required for employers using Table 
1. In the case where an employee may have disease related to respirable 
crystalline silica and the employer has properly implemented 
engineering controls, the only further action by the employer would be 
to follow PLHCP recommendations to protect the worker who may be 
especially sensitive to continuing exposure and need special 
accommodations. Such recommendations could include limitations on 
respirator use; they might also include specialist referral or 
limitations on respirable crystalline silica exposure (if the employee 
gives authorization for the employer to receive this information) 
(paragraph (i)(6)(i)(C) or (ii)(A) and (B) of the standard for general 
industry and maritime and paragraph (h)(6)(i)(C) or (ii)(A) and (B) of 
the standard for construction).
    In taking a more consent-based approach than in the proposed rule 
regarding the PLHCP's written medical opinion for the employer, OSHA 
considered the countervailing factor that employers will not be able to 
report occupational illnesses to OSHA if they are not given medical 
surveillance information. USW refuted the utility of employer reporting 
of workplace illnesses, stating:

    However, this loss is minor, because few believe that such 
employer-generated reporting of chronic occupational conditions 
does, or even could, under the best of circumstances, provide proper 
counts of occupational illnesses (Document ID 4214, p. 8).

On a similar note, Fann Contracting and ASSE requested clarification on 
what information would be reportable or recordable (Document ID 2116, 
Attachment 1, p. 20; 2339, p. 9).
    This rule does not change OSHA reporting or recording requirements, 
and employers who need more information on recording or reporting of 
occupational illnesses should refer to OSHA's standard on recording and 
reporting occupational injuries and illnesses (29 CFR 1904). OSHA finds 
that if employees do not participate in medical surveillance because of 
discrimination or retaliation fears, illnesses associated with 
respirable crystalline silica would generally not be identified. 
Although not disclosing medical information to employers appears 
inconsistent with the objective of recording illnesses, the net effect 
of that decision is improving employee protections due to more 
employees participating in medical surveillance. Also, as noted above, 
OSHA never intended for employers to get specific information, such as 
diagnoses, and this would further limit employers' ability to report 
disease. Although state surveillance systems are likely to 
underestimate silicosis cases (see Section V, Health Effects), they are 
still likely to be a better way to get information on trends of 
silicosis cases than employer reports. Reporting of silicosis cases by 
health care providers is required by 25 states (see http://www.cste2.org/izenda/ReportViewer.aspx?rn=Condition+All&p1value=2010&p2value=Silicosis). 
PLHCPs are more likely to have the information needed to report 
silicosis cases to state health authorities than employers. Thus, OSHA 
concludes that exclusion of health-related information from the PLHCP's 
written medical opinion for the employer will not have a significant 
impact on silicosis surveillance efforts.
    An additional consideration relating to what information, if any, 
goes to the employer is that withholding information, such as 
conditions that might place an employee at risk of health impairment 
with further exposure, may leave employers with no medical basis to aid 
in the placement of employees. Although NSSGA did not want to receive 
confidential medical records, it stressed the importance of continuing 
to receive information concerning how the workplace could affect an 
employee's condition and on recommended respirator restrictions 
(Document ID 3583, Tr. 2315-2316; 4026, p. 5). NISA stated that 
employers should receive the results of medical surveillance because 
employers might be held liable if employees choose to keep working in 
settings that might aggravate their illnesses (Document ID 4208, p. 
14). However, labor unions, such as USW, BAC, and BCTD, strongly 
opposed employers making job placement decisions based on employees' 
medical findings (Document ID 4214, pp. 7-8; 4219, pp. 31-32; 4223, p. 
133). USW and BCTD noted that as long as employees are capable of 
performing their work duties, decisions to continue working should be 
theirs; BCTD further noted that the employee should make such decisions 
with guidance from the PLHCP, and USW noted that the employee should 
decide because of the significance of job loss or modifications 
(Document ID 2371, Attachment 1, pp. 45-46; 4214, pp. 7-8). Sarah Coyne 
agreed that employees should make decisions about placement. Ms. Coyne 
stated, ``I might have silicosis. I might have asbestosis. I know if I 
can work or not. Let me decide'' (Document ID 3581, Tr. 1656).
    OSHA agrees that employees have the most at stake in terms of their 
health and employability, and they should not have to choose between 
continued employment and the health benefits offered by medical 
surveillance, which they are entitled to under the OSH Act. OSHA agrees 
that employees should make employment decisions, following discussions 
with the PLHCP that include the risks of continued exposure. Before 
that can happen, however, employees need to have confidence that 
participation in medical surveillance will not threaten their 
livelihoods. After considering the various viewpoints expressed during 
the rulemaking on these issues, OSHA concludes that the best way to 
maximize employee participation in medical surveillance, therefore 
promoting the protective and preventative purposes of this rule, is by 
limiting required disclosures of information to the employer to only 
the bare minimum of what the employer needs to know to protect employee 
health--recommended restrictions on respirator use and, only with 
consent of the employee, the PLHCP's recommended limitations on 
exposure to respirable crystalline silica and specialist referrals. 
Thus, OSHA views this consent-based approach to reporting of medical 
surveillance findings critical to the ultimate success of this 
provision, which will be measured not just in the participation rate, 
but in the benefits to participating employees--early detection of 
silica-related disease so that employees can make employment, 
lifestyle, and medical decisions to mitigate adverse health effects and 
to possibly retard progression of the disease.
    Expressing a different view, CISC stated that OSHA lacks the legal

[[Page 16834]]

authority to require employers to pay for ongoing medical surveillance 
with no nexus to the workplace (Document ID 4217, p. 24). However, the 
medical surveillance requirement in this rule, and every OSHA rule, 
does have a nexus to the workplace. In the case of the respirable 
crystalline silica rule, the nexus to the workplace is that exposure in 
the workplace can result in or exacerbate disease and that medical 
surveillance information will allow employees to make health and 
lifestyle decisions that will benefit both them and the employer. In 
addition, medical surveillance provides the employer with information 
on fitness to wear a respirator, which is vitally important because of 
risks to employees who wear a respirator when they should not do so 
because of medical reasons.
    NISA supported providing the proposed medical opinion to employers, 
partly because some employers might have a better understanding of 
medical surveillance results than employees, who might not have the 
training or understanding to make health-protective decisions based on 
those results (Document ID 4208, pp. 13-14). OSHA recognizes that 
larger companies that employ health, safety, and medical personnel may 
have in-house expertise to answer employee questions and stress the 
importance of protective measures, such as work practices or proper use 
of respirators. However, it is not likely that owners or management of 
small companies would have a better understanding than their employees 
or would be able to provide them any additional guidance. Consequently, 
OSHA does not find the fact some employers might have a better 
understanding of medical surveillance results than employees to be a 
compelling argument against limiting the information that is to be 
reported to the employer in the absence of employee consent. In 
addition, OSHA expects that the training required under the rule will 
give employees knowledge to understand protective measures recommended 
by the PLHCP.
    In sum, OSHA concludes that the record offers compelling evidence 
for modifying the proposed content of the PLHCP's written medical 
opinion for the employer. The evidence includes privacy concerns 
expressed by both employees and employers, as well as evidence on the 
limited utility for giving medical surveillance findings to employers. 
OSHA is particularly concerned that the proposed requirements would 
have led to many employees not participating in medical surveillance 
and therefore not receiving its benefits. OSHA therefore has limited 
the information to be given to the employer under this rule, but is 
requiring that the employee receive a separate written medical report 
with more detailed medical information.
    The requirements for the type of information provided to the 
employer are different from requirements of other OSHA standards, which 
remain in effect for those other standards. The requirements for this 
rule are based on the evidence obtained during this rulemaking for 
respirable crystalline silica, in particular that many employees would 
not take advantage of medical surveillance without privacy protections 
and because the findings of medical examinations would not likely 
reflect current workplace conditions in most cases. The action taken in 
this rulemaking does not preclude OSHA from adopting its traditional 
approach, or any other approach for reporting of medical findings to 
employers, in the future when it concludes, based on health effects 
information, that such an approach would contribute information that is 
relevant to current workplace conditions and would allow for design or 
implementation of controls to protect other employees.
    PLHCP's written medical report for the employee. OSHA did not 
propose a separate report given directly by the PLHCP to the employee, 
but as discussed in detail above, several commenters requested that a 
report containing medical information only be given to the employee. 
OSHA agrees and in response to those comments, paragraph (i)(5) of the 
standard for general industry and maritime (paragraph (h)(5) of the 
standard for construction) requires the employer to ensure that the 
PLHCP explains the results of the medical examination and provides the 
employee with a written medical report within 30 days.
    The contents of the PLHCP's written medical report for the employee 
are set forth in paragraphs (i)(5)(i)-(iv) of the standard for general 
industry and maritime (paragraphs (h)(5)(i)-(iv) of the standard for 
construction). They include: The results of the medical examination, 
including any medical condition(s) that would place the employee at 
increased risk of material impairment of health from exposure to 
respirable crystalline silica and any medical conditions that require 
further evaluation or treatment; any recommended limitations on the 
employee's use of respirators; any recommended limitations on 
respirable crystalline silica exposure; and a statement that the 
employee should be examined by a specialist if the chest X-ray provided 
in accordance with this section is classified as 1/0 or higher by the B 
reader, or if referral to a specialist is deemed appropriate by the 
PLHCP. Appendix B contains an example of a PLHCP's written medical 
report for the employee.
    The health-related information in the PLHCP's written medical 
report for the employee is generally consistent with the proposed 
PLHCP's written medical opinion for the employer, with two notable 
exceptions. Because only the employee will be receiving the PLHCP's 
written medical report, the written medical report may include 
diagnoses and specific information on health conditions, including 
those not related to respirable crystalline silica, and medical 
conditions that require further evaluation or follow-up are not limited 
to those related to respirable crystalline silica exposure. Although 
the focus of the examination is on silica-related conditions, the PLHCP 
may happen to detect health conditions that are not related to 
respirable crystalline silica exposure during the examination, and 
could include information about such conditions in the written medical 
report for the employee. The employer, however, is not responsible for 
further evaluation of conditions not related to respirable crystalline 
silica exposure. A minor difference from the proposed written medical 
opinion for the employer and the written medical report for the 
employee in the rule is that it specifies limitations on respirator use 
rather than PPE because respirators are the only type of PPE required 
by the rule. The requirements for the PLHCP's written medical report 
for the employee are consistent with the overall goals of medical 
surveillance: To identify respirable crystalline silica-related adverse 
health effects so that the employee can consider appropriate steps to 
manage his or her health; to let the employee know if he or she can be 
exposed to respirable crystalline silica in his or her workplace 
without increased risk of experiencing adverse health effects; and to 
determine the employee's fitness to use respirators. By providing the 
PLHCP's written medical report to employees, those who might be at 
increased risk of health impairment from respirable crystalline silica 
exposure will be able to consider interventions (i.e., health 
management strategies) with guidance from the PLHCP. Dr. Laura Welch 
testified that her recommendations to a patient diagnosed with 
silicosis would include employment choices to limit exposures, using a 
respirator for additional protection, quitting smoking, and

[[Page 16835]]

getting influenza and pneumonia vaccines (Document ID 3581, p. 1663).
    The requirement for a verbal explanation in paragraph (i)(5) of the 
standard for general industry and maritime (paragraph (h)(5) of the 
standard for construction) allows the employee to confidentially ask 
questions or discuss concerns with the PLHCP. The requirement for a 
written medical report ensures that the employee receives a record of 
all findings. As noted by BCTD, giving the employee the written report 
will ensure the employee understands medical conditions that require 
follow-up and could affect decisions of where and how to work; BCTD 
also noted that employees would be able to provide the PLHCP's written 
medical report to future health care providers (Document ID 2371, 
Attachment 1, p. 48); this would include PLHCPs conducting subsequent 
periodic examinations under the rule.
    PLHCP's written medical opinion for the employer. As discussed in 
detail above, many commenters objected to OSHA's proposed content for 
the PLHCP's written medical opinion for the employer based on employee 
privacy concerns. OSHA agrees with these privacy concerns and is thus 
revising the contents of the written medical opinion. In developing the 
contents of the PLHCP's written medical opinion for the employer, OSHA 
considered what type of information needs to be included to provide 
employers with information to protect employee health, while at the 
same time protecting employee privacy. Commenters representing labor 
unions and the medical community stated that the only information that 
employers need to know is limitations on respirator use (Document ID 
2178, Attachment 1, p. 5; 2240, pp. 3-4; 2282, Attachment 3, p. 21; 
2336, p. 12; 3589, Tr. 4207; 4196, p. 6; 4203, p. 6; 4204, p. 89; 4219, 
pp. 31-32; 4223, p. 133). Dr. Laura Welch stated that giving the 
employer information on an employee's ability to use a respirator, but 
not specific medical information, strikes the appropriate balance 
between the employee's privacy and the employer's right to know; she 
noted that employees who are not fit to wear a respirator and then do 
can be at risk of sudden incapacitation or death (Document ID 3581, Tr. 
1582, 1662).
    BCTD further noted that the medical surveillance model it is 
recommending for respirable crystalline silica presents a different 
circumstance than what it advocated for regarding asbestos in 
Industrial Union Department, AFL-CIO v. Hodgson. There, the union was 
not granted its request for results of medical examinations to be given 
to the employer only with the employees' consent under the asbestos 
standard. The court ruled that employers needed the medical results 
because the asbestos standard requires employers to reassign employees 
without loss of pay or seniority if the employee was found unable to 
safely wear a respirator. For respirable crystalline silica, BCTD has 
concluded that providing employers with information regarding 
limitations on respirator use and nothing else that is medically 
related is reasonable if the employee is not requesting accommodations 
or additional examinations from the employer (Document ID 4223, pp. 
134-135).
    Based on record evidence, OSHA has determined that for the 
respirable crystalline silica rule, the PLHCP's written medical opinion 
for the employer must contain only the date of the examination, a 
statement that the examination has met the requirements of this 
section, and any recommended limitations on the employee's use of 
respirators. These requirements are laid out in paragraphs 
(i)(6)(i)(A)-(C) of the standard for general industry and maritime 
(paragraphs (h)(6)(i)(A)-(C) of the standard for construction). OSHA is 
persuaded by arguments to include limitations on respirator use, and no 
other medically-related information, in the PLHCP's written medical 
opinion for the employer. The Agency notes that the limitation on 
respirator use is consistent with information provided to the employer 
under the respiratory protection standard (29 CFR 1910.134). OSHA 
concludes that only providing information on respirator limitations in 
the PLHCP's written medical opinion for the employer is consistent with 
the ACOEM confidentiality guidelines that recommend reporting of health 
and safety concerns to the employer (Document ID 3622, p. 2). The date 
and statement about the examination meeting the requirements of this 
section are to provide both the employer and employee with evidence 
that requirements for medical surveillance are current. Employees would 
be able to show this opinion to future employers to demonstrate that 
they have received the medical examination, as was recommended by 
LHSFNA and BCTD (Document ID 4207, p. 5; 4223, p. 125).
    Paragraphs (i)(6)(ii)(A)-(B) of the standard for general industry 
and maritime (paragraphs (h)(6)(ii)(A)-(B) of the standard for 
construction) state that if the employee provides written 
authorization, the written medical opinion for the employer must also 
contain either or both of the following: (1) Any recommended 
limitations on exposure to respirable crystalline silica; (2) a 
statement that the employee should be examined by a specialist if the 
chest X-ray provided in accordance with this section is classified as 
1/0 or higher by the B reader, or if referral to a specialist is 
otherwise deemed appropriate by the PLHCP. OSHA intends for this 
provision to allow the employee to give authorization for the PLHCP's 
written medical opinion for the employer to contain only the 
recommendation on exposure limitations, only the recommendation for 
specialist referral, or both recommendations. The Agency expects that 
the written authorization could easily be accomplished through the use 
of a form that allows the employee to check, initial, or otherwise 
indicate which (if any) of these items the employee wishes to be 
included in the PLHCP's written medical opinion for the employer. An 
example of an authorization form is included in Appendix B.
    OSHA is convinced that routinely including recommended limitations 
on respirable crystalline silica exposure and specialist referrals in 
the PLHCP's written medical opinion for the employer could adversely 
affect employees' willingness to participate in medical surveillance. 
The requirements for this paragraph are consistent with recommendations 
from labor unions. For example, UAW, BAC, and BCTD suggested letting 
the employee decide to forward the recommendation for an examination by 
a specialist if the employee wanted the employer to cover the costs of 
that examination (Document ID 3582, Tr. 1909; 4219, p. 32; 4223, pp. 
133-134). BAC and BCTD also stated the employee should decide whether 
recommended accommodations (i.e., recommended limitations on exposure) 
should be reported to the employer. As both BAC and BCTD emphasized, 
information given to the employer should only indicate that a referral 
is recommended and the nature of the limitation on exposure, not an 
underlying diagnosis. OSHA considers this reasonable. Appendix B 
contains an example of a PLHCP's written medical opinion for the 
employer.
    OSHA finds that this new format for the PLHCP's medical opinion for 
respirable crystalline silica will better address concerns of NAHB and 
Dow Chemical, who feared they would be in violation if the PLHCP's 
written medical opinion for the employer included information that OSHA 
proposed the PLHCP not report to the employer, such as an unrelated 
diagnosis (Document ID 2270, p. 4; 2296, pp. 31-32). OSHA finds that 
removing the prohibition on

[[Page 16836]]

unrelated diagnoses and instead specifying the only information that is 
to be included in the PLHCP's written medical opinion for the employer 
remedies this concern because it makes the contents of the opinion 
easier to understand and less subject to misinterpretation. The new 
format also addresses NAHB's request that PLHCPs' opinions be 
standardized so that employers could understand the results (Document 
ID 2296, pp. 31-32).
    OSHA recognizes that some employees might be exposed to multiple 
OSHA-regulated substances at levels that trigger medical surveillance 
and requirements for written opinions. The PLHCP can opt to prepare one 
written medical opinion for the employer for each employee that 
addresses the requirements of all relevant standards, as noted in 
preambles for past rulemakings, such as chromium (VI) (71 FR 10100, 
10365 (2/28/06)). However, the combined written medical opinion for the 
employer must include the information required under each relevant OSHA 
standard. For example, if the PLHCP opts to combine written medical 
opinions for an employee exposed to both chromium (VI) and respirable 
crystalline silica in a workplace covered by construction standards, 
then the combined opinion to the employer must contain the information 
required by paragraphs (i)(5)(A)-(C) of the chromium (VI) standard for 
construction (29 CFR 1926.1126) and the information required by 
paragraphs (h)(6)(i)(A)-(C) (and paragraphs (h)(6)(ii)(A)-(B), with 
written authorization from the employee) of the respirable crystalline 
silica standard for construction.
    Other commenter recommendations for information to be included in 
the PLHCP's written medical opinion for the employer were not adopted 
by OSHA. Collegium Ramazzini and BCTD requested that the PLHCP's 
written medical opinion for the employer contain a statement that the 
employee was informed that respirable crystalline silica increases the 
risk of lung cancer, and Collegium Ramazzini also requested that the 
opinion indicate that the employee was told that smoking can compound 
the risk of developing lung cancer with exposure to respirable 
crystalline silica (Document ID 3541, p. 14; 4223, p. 137). On a 
similar note, Collegium Ramazzini also requested that employers 
establish smoking cessation programs (Document ID 3541, p. 4). OSHA 
notes that training provisions in paragraph (j)(3)(i)(A) of the 
standard for general industry and maritime (paragraph (i)(2)(i)(A) of 
the standard for construction) already require employers to ensure that 
each employee can demonstrate knowledge of the health hazards 
associated with exposure to respirable crystalline silica, which 
include lung cancer. OSHA concludes that the training required under 
the respirable crystalline silica rule is sufficient to inform 
employees about lung cancer risk.
    Labor unions including UAW, CWA, USW, AFL-CIO, and BCTD requested 
that the rule prohibit employers from asking employees or the PLHCP for 
medical information (Document ID 2282, Attachment 3, p. 21; 2240, pp. 
3-4; 2336, p. 12; 4204, p. 90; 4223, p. 134); as most of these 
commenters noted, a similar prohibition is included in the black lung 
rule for coal miners (30 CFR 90.3). OSHA is not including such a 
prohibition in the rule because employers may have legitimate reasons 
for requesting medical information, such as X-ray findings, to conduct 
epidemiology studies, and if employees are not concerned about 
discrimination or retaliation, they could authorize the employer to 
receive such information.
    The proposed written medical opinion for the employer called for a 
statement that the PLHCP had explained to the employee the results of 
the medical examination, including findings of any medical conditions 
related to respirable crystalline silica exposure that require further 
evaluation or treatment, and any recommendations related to use of 
protective clothing or equipment. As noted above, OSHA has retained the 
requirement that the employer ensure that the PLHCP explains the 
results to the employee in paragraph (i)(5) of the standard for general 
industry and maritime (paragraph (h)(5) of the standard for 
construction), but no longer requires the PLHCP to include a statement 
of this fact in the written medical opinion for the employer. OSHA is 
not mandating how the employer ensures that the employee gets the 
required information because there are various ways this could be done, 
such as in a contractual agreement between the employer and PLHCP. 
PLHCPs could still include the verification in the PLHCP's written 
medical opinion for the employer if that is a convenient method for 
them to do so.
    Paragraph (i)(6)(iii) of the standard for general industry and 
maritime (paragraph (h)(6)(iii) of the standard for construction) 
requires the employer to ensure that employees receive a copy of the 
PLHCP's written medical opinion for the employer within 30 days of each 
medical examination performed. OSHA is requiring that employees receive 
a copy of the PLHCP's written medical opinion for the employer because 
they can present it as proof of a current medical examination to future 
employers. This is especially important in industries with high 
turnover because employees may work for more than one employer during a 
three-year period and this ensures that tests, such as X-rays, are not 
performed more frequently than required.
    As indicated above, the rule requires that employers ensure that 
employees get a copy of the PLHCP's written medical report and opinion 
and that they get a copy of the PLHCP's opinion within 30 days of each 
medical examination (paragraphs (i)(5), (6)(i), and (6)(iii) of the 
standard for general industry and maritime, paragraphs (h)(5), (6)(i), 
and (6)(iii) of the standard for construction). By contrast, the 
proposed rule would have required that the employer obtain the PLHCP's 
written medical opinion within 30 days of the medical examination and 
then provide a copy to the employee within 2 weeks after receiving it. 
Dow Chemical expressed concern about compliance if a PLHCP took more 
than 30 days to deliver the PLHCP's written medical opinion, which is a 
situation that is out of the employer's control (Document ID 2270, p. 
4). Ameren and EEI requested 30 days for the employer to give the 
employee a copy of the PLHCP's written medical opinion (Document ID 
2315, p. 4; 2357, p. 35).
    The purpose of these requirements is to ensure that the employee 
and employer are informed in a timely manner. To ensure timely delivery 
and demonstrate a good faith effort in meeting the requirements of the 
standard, the employer could inform PLHCPs about the time requirements 
and follow-up with PLHCPs if there is concern about timely delivery of 
these documents. Similar 30-day requirements are included in other OSHA 
standards, such as chromium (VI) (1910.1026) and methylene chloride 
(1910.1052). Because the PLHCP will be providing the employee with a 
copy of the PLHCP's written medical report, he or she could give the 
employee a copy of the written medical opinion at the same time. This 
would eliminate the need for the employer to give the employee a copy 
of the PLHCP's written medical opinion for the employer, but the 
employer would still need to ensure timely delivery.
    Additional examinations with a specialist. Paragraph (i)(7)(i) of 
the standard for general industry and maritime (paragraph (h)(7)(i) of 
the standard for construction) requires that the employer make 
available a medical examination by a specialist within 30

[[Page 16837]]

days of receiving the written medical opinion in which the PLHCP 
recommends that the employee be examined by a specialist. As is the 
case with the PLHCP's examination, the employer is responsible for 
providing the employee with a medical examination by a specialist, at 
no cost, and at a reasonable time and place, if the employer receives a 
PLHCP's referral recommendation.
    OSHA proposed referral to a specialist under two circumstances: (1) 
Where a B reader classifies an employee's chest X-ray as 1/0 or higher 
and (2) where the PLHCP determines referral is otherwise appropriate. 
The first trigger point for specialist referral relates to the 
interpretation and classification of the chest X-ray employees receive 
as part of their initial or periodic medical examination. The second 
trigger point empowers the PLHCP to refer the employee to a specialist 
for any other appropriate reason. After considering the comments on the 
proposed rule (discussed below), OSHA retained the triggers for 
referral in Paragraphs (i)(5)(iv) and (i)(6)(ii)(B) of the standard for 
general industry and maritime (paragraphs (h)(5)(iv) and (h)(6)(ii)(B) 
of the standard for construction).
    As discussed above, paragraph (i)(2)(iii) of the standard for 
general industry and maritime (paragraph (h)(2)(iii) of the standard 
for construction) requires that X-rays be interpreted according to the 
ILO classification system. The ILO's system is a standardized manner of 
classifying opacities seen in chest radiographs. It describes the 
presence and severity of pneumoconiosis on the basis of size, shape, 
and profusion (concentration) of small opacities, which together 
indicate the severity and extent of lung involvement (Document ID 
1475). The profusion of opacities seen on chest radiographs is compared 
to standard X-rays and classified on a 4-point category scale (0, 1, 2, 
or 3), with each category representing increasing profusion of small 
opacities. Each category is divided into two subcategories, giving a 
12-subcategory scale between 0/- and 3/+. The first subcategory value 
represents the B Reader's first choice for profusion rating and the 
second subcategory value represents the B Reader's second choice for 
profusion rating. CDC/NIOSH considers a category 1/0 X-ray to be 
consistent with silicosis (Document ID 1711, p. 41).
    The respirable crystalline silica rule's 1/0 category trigger point 
for referral is lower than in the ASTM standards, which recommend that 
employees with profusion opacities greater than 1/1 be evaluated at a 
frequency determined by a physician qualified in pulmonary disease 
(Section 4.7.1 of E 1132-06 and E 2625-09) and receive annual 
counseling by a physician or other person knowledgeable in occupational 
safety and health (Section 4.7.2 of E 1132-06 and E 2625-09) (Document 
ID 1466, p. 5; 1504, p. 5). CISC questioned what medical evidence OSHA 
had that a specialist is necessary at this stage and stated that OSHA 
did not explain why it deviated from the ASTM standard (Document ID 
2319, p. 120). However, ACOEM agreed with a cut-off point of 1/0 for 
abnormality, and ATS agreed with specialist referral at a category of 
1/0 (Document ID 2080, p. 7; 2175, p. 6).
    Other evidence in the record also weighs in favor of referral where 
an employee's X-ray is classified as 1/0 or higher. For example, a 
study by Hnizdo et al. (1993) compared X-rays read by B Readers to 
autopsy findings and demonstrated that a classification of 1/0 is 
highly specific for radiological silicosis, with 89 percent of 1/0 
readings of radiological silicosis found to be true positives (Document 
ID 1050, pp. 427, 440). Based on the high level of specificity for 1/0 
readings, i.e., the low probability of a false positive reading, OSHA 
concludes it is appropriate to address silicosis at that stage to allow 
for earlier intervention to possibly slow disease progression and 
improve health. Therefore, based on the evidence in the record, OSHA 
decided to retain the 1/0 or higher trigger point for referral to a 
specialist.
    OSHA also decided to retain the second referral trigger point 
contained in the proposed rule: Referral to a specialist if otherwise 
deemed appropriate by the PLHCP. Such referrals based on a PLHCP's 
written medical opinion for the employer allow potential findings of 
concern to be investigated further. Together, the two triggers for 
specialist referral in this rule are intended to ensure that employees 
with abnormal findings can be given the opportunity to be seen by an 
American Board Certified Specialist with expertise in pulmonary disease 
or occupational medicine, who can provide not only expert medical 
judgment, but also counseling regarding work practices and personal 
habits that could affect these individuals' respiratory health.
    As indicated above, the employee must provide written authorization 
before the PLHCP's written medical opinion for the employer may include 
a recommendation for specialist examination (paragraph (i)(6)(ii)(B) of 
the standard for general industry and maritime, paragraph (h)(6)(ii)(B) 
of the standard for construction). If the employer's opinion contains a 
recommendation for specialist referral, then paragraph (i)(7)(i) of the 
standard for general industry and maritime (paragraph (h)(7)(i) of the 
standard for construction) requires the employer to make available a 
medical examination by a specialist within 30 days after receiving the 
PLHCP's written medical opinion. If the employer does not receive the 
PLHCP's referral because the employee did not authorize the employer to 
receive it, then the employer is not responsible for offering 
additional examinations and covering their costs.
    Although the criteria for referral, i.e., X-ray classification or 
PLHCP's opinion that a referral is appropriate, have not changed since 
the proposed rule, the professional to whom the employee would be 
referred has changed. Specifically, the proposed rule would have 
required the employer to provide the referred employee with a medical 
examination with a pulmonary disease specialist. As discussed further 
in the summary and explanation of Definitions, OSHA agreed with a 
number of commenters that an occupational medicine specialist is 
qualified to examine employees referred for a possible respirable 
crystalline silica-related disease (Document ID 2215, p. 9; 2291, p. 
26; 2348, Attachment 1, p. 40; 3577, Tr. 778; 4223, p. 129). Therefore, 
the Agency has added the term ``specialist'' to the definitions in 
paragraph (b) of the rule and defined the term to mean an American 
Board Certified Specialist in Pulmonary Disease or an American Board 
Certified Specialist in Occupational Medicine. Paragraphs (i)(5)(iv) 
and (i)(6)(ii)(B) of the standard for general industry and maritime 
(paragraphs (h)(5)(iv) and (h)(6)(ii)(B) of the standard for 
construction) were also revised to specify referral to a 
``specialist.''
    Paragraph (i)(7)(i) of the standard for general industry and 
maritime (paragraph (h)(7)(i) of the standard for construction) sets 
time limits for additional examinations to be made available. 
Specifically, it requires that the employer make available a medical 
examination by a specialist within 30 days of receiving a written 
medical opinion in which the PLHCP recommends that the employee be 
examined by a specialist. This requirement is unchanged from the 
proposed rule. Some commenters, including Dow Chemical, Ameren, and 
EEI, commented that it might take more than 30 days to get an 
appointment with a specialist (e.g., Document ID 2270, p. 5; 2315, p. 
4; 2357, p. 36). OSHA does

[[Page 16838]]

not expect this will be the case based on the numbers of available 
specialists in the U.S. As of March 10, 2015, the American Board of 
Internal Medicine (ABIM) reported that 13,715 physicians in the U.S. 
had valid certificates in pulmonary disease (see http://www.abim.org/pdf/data-candidates-certified/all-candidates.pdf). ABIM does not report 
how many of these physicians are practicing. However, ABIM does report 
that more than 400 new certificates in pulmonary disease were issued 
per year from 2011 to 2014 and a total of 4,378 new certificates in 
pulmonary disease were issued in the period from 2001 to 2010 (see 
http://www.abim.org/pdf/data-candidates-certified/Number-Certified-Annually.pdf). Because physicians are likely to practice for some time 
after receiving their certification, the numbers indicate that a 
substantial number of pulmonary disease specialists are available in 
the U.S. The American Board of Preventative Medicine reports that 
between 2001 and 2010, 863 physicians passed their examinations for 
board certification in occupational medicine (see https://www.theabpm.org/pass_rates.cfm). In a comparison with total numbers of 
physicians who were board certified in pulmonary disease during 2001 to 
2010, the addition of board certified occupational medicine physicians 
will likely increase specialist numbers by approximately 20 percent. 
The expansion of the specialist definition to board certified 
occupational medicine physicians will mean that more physicians will be 
available for referrals, making appointments easier to get. 
Consequently, OSHA considers the 30-day period to be reasonable, and 
expects that this deadline will ensure that employees receive timely 
examinations.
    Under paragraph (i)(7)(ii) of the standard for general industry and 
maritime (paragraph (h)(7)(ii) of the standard for construction), the 
employer must provide the specialist with the same information that is 
provided to the PLHCP (i.e., a copy of the standard; a description of 
the employee's former, current, and anticipated duties as they relate 
to respirable crystalline silica exposure; the employee's former, 
current, and anticipated exposure level; a description of any PPE used, 
or to be used, by the employee, including when and for how long the 
employee has used or will use that equipment; and information from 
records of employment-related medical examinations previously provided 
to the employee and currently within the control of the employer). The 
information the employer is required to give the specialist is largely 
unchanged from the proposed rule. The few changes and the reasons why 
the specialist should receive this information are the same as those 
for the PLHCP and are addressed above.
    Under paragraph (i)(7)(iii) of the standard for general industry 
and maritime (paragraph (h)(7)(iii) of the standard for construction), 
the employer must ensure that the specialist explains medical findings 
to the employee and gives the employee a written medical report 
containing results of the examination, including conditions that might 
increase the employee's risk from exposure to respirable crystalline 
silica, conditions requiring further follow-up, recommended limitations 
on respirator use, and recommended limitations on respirable 
crystalline silica exposure. The reasons why the specialist is to give 
the employee this information and the changes from the proposed rule 
are discussed above, under the requirements for the PLHCP's written 
medical report for the employee. For the same reasons as addressed 
above, paragraph (i)(7)(iv) of the standard for general industry and 
maritime (paragraph (h)(7)(iv) of the standard for construction) 
requires the specialist to provide the employer with a written medical 
opinion indicating the date of the examination, any recommended 
limitations on the employee's use of respirators, and with the written 
authorization of the employee, any recommended limitations on the 
employee's exposure to respirable crystalline silica.
    The rule does not address further communication between the 
specialist and the referring PHLCP. OSHA expects that because the PLHCP 
has the primary relationship with the employer and employee, the 
specialist may want to communicate his or her findings to the PLHCP and 
have the PLHCP simply update the original written medical report for 
the employee and written medical opinion for the employer and employee. 
This is permitted under the rule, so long as all requirements and time 
deadlines are met.
    Medical removal protection. Some OSHA standards contain provisions 
for medical removal protection (MRP) that typically require the 
employer to temporarily remove an employee from exposure when such an 
action is recommended in a written medical opinion. During the time of 
removal, the employer is required to maintain the employee's total 
normal earnings, as well as all other employee rights and benefits. MRP 
provisions vary among health standards, depending on the hazard, the 
adverse health effects, medical surveillance requirements, and the 
evidence presented during the particular rulemaking. Although virtually 
every previous OSHA substance-specific health standard includes 
provisions for medical surveillance, OSHA has found MRP necessary for 
only six of those standards. They are lead (1910.1025), cadmium 
(1910.1027), benzene (1910.1028), formaldehyde (1910.1048), 
methylenedianiline (1910.1050), and methylene chloride (1910.1052).
    OSHA did not include a provision for MRP in the proposed rule 
because the Agency preliminarily concluded that there would be few 
instances where temporary removal and MRP would be useful. However, 
OSHA asked for comment on whether the rule should include an MRP 
provision, which medical conditions or findings should trigger 
temporary removal, and what should be the maximum period for receiving 
benefits (78 FR at 56291).
    Labor groups, industry representatives, the medical community, and 
other employee health advocates offered comments on this issue. NIOSH, 
ASSE, and some employers and industry groups agreed with OSHA's 
preliminary findings that MRP or temporary removal from exposure is not 
appropriate for the respirable crystalline silica rule (e.g., Document 
ID 2116, Attachment 1, pp. 44-45; 2177, Attachment B, p. 39; 2195, p. 
44; 2319, p. 129; 2327, Attachment 1, p. 27; 2339, p. 10; 2357, p. 35; 
2379, Appendix 1, p. 72). Among the reasons noted were an inability to 
relocate employees to different positions, interference with workers' 
compensation systems, or the permanent nature of silica-related health 
effects.
    CWA, UAW, USW, and AFL-CIO advocated for the inclusion of MRP (in 
the general industry and maritime standard) with provisions for 
multiple physician review, similar to MRP in cadmium (Document ID 2240, 
p. 4; 2282, Attachment 3, pp. 23-24; 3584, Tr. 2541-2546; 4204, pp. 91-
98). None of the labor groups requested an MRP provision for the 
construction standard. According to Collegium Ramazzini and AFL-CIO, 
benefits of MRP include: Encouraging employees to participate in 
medical surveillance and allowing for transfer when an employee is 
unable to wear a respirator (e.g., cadmium, asbestos, cotton dust); 
they further indicated that MRP is appropriate for the respirable 
crystalline silica rule because it can be applied when employees are 
referred to a specialist (e.g., benzene) and it is not limited to

[[Page 16839]]

permanent conditions in other OSHA standards. AFL-CIO further commented 
that MRP gives employers time to find other positions involving lower 
exposures for at-risk workers, and indicated that it is widely 
supported by physicians (Document ID 3541, pp. 16-17; 4204, pp. 94-97). 
Physicians representing employee health advocate or public health 
groups testified or commented that removal from exposure can prevent or 
slow progression of silicosis or benefit employees during short-term 
periods of COPD exacerbation, which can be further exacerbated with 
continued exposure to respirable crystalline silica (Document ID 2244, 
p. 4; 3577, Tr. 830-832; 3541, p. 16).
    OSHA did not propose MRP for respirable crystalline silica because 
the adverse health effects associated with respirable crystalline 
silica exposure (e.g., silicosis) are chronic conditions that are not 
remedied by temporary removal from exposure. In contrast, removal under 
the cadmium standard (29 CFR 1910.1027) could allow for biological 
monitoring results to return to acceptable levels or for improvement in 
the employee's health. The evidence submitted during the rulemaking has 
led OSHA to conclude that its preliminary reasoning was correct and 
that for the reasons discussed below, there will be few instances where 
temporary removal from respirable crystalline silica exposures would 
improve employee health.
    OSHA has declined to adopt MRP provisions in other health standards 
under similar circumstances. For example, in its chromium (VI) 
standard, OSHA did not include an MRP provision because chromium (VI)-
related health effects are either chronic conditions that will not be 
improved by temporary removal from exposure (e.g., lung cancer, 
respiratory or dermal sensitization), or they are conditions that can 
be addressed through proper application of control measures (e.g., 
irritant dermatitis) (71 FR at 10366). OSHA did not include MRP 
provisions in the ethylene oxide (EtO) standard, concluding that,

. . . the effects of exposure to EtO are not highly reversible, as 
evidenced by the persistence of chromosomal aberrations after the 
cessation of exposure, and the record contains insufficient evidence 
to indicate that temporary removal would provide long-term employee 
health benefits (49 FR 29734, 25788 (6/22/1984)).

    Similarly, the 1,3-butadiene standard, which primarily addresses 
irreversible effects, such as cancer, does not include MRP provisions 
(61 FR 56746 (11/4/96)).
    OSHA recognizes that some employees might benefit from removal from 
respirable crystalline silica exposure to possibly prevent further 
progression of disease. However, the health effects evidence suggests 
that crystalline silica-related diseases are permanent (Document ID 
2177, Attachment B, p. 39). Thus, to be beneficial, any such removals 
would have to be permanent, not temporary. Even in cases where 
employees might benefit from temporary removal, such as to alleviate 
exacerbation of COPD symptoms, COPD itself is not reversible. In 
response to commenters indicating that temporary removal might 
alleviate COPD symptoms, OSHA anticipates that periods of exacerbation 
will continue to recur absent permanent removal from respirable 
crystalline silica exposure. OSHA views MRP as a tool for dealing with 
temporary removals only, as reflected in the Agency's decisions not to 
adopt MRP in the chromium (VI), ethylene oxide, and 1,3-butadiene 
standards. Workers' compensation is the appropriate remedy when 
permanent removal from exposure is required.
    When the D.C. Circuit Court reviewed OSHA's initial decision not to 
include MRP in its formaldehyde standard, it remanded the case for OSHA 
to consider the appropriateness of MRP for permanently removed 
employees (see UAW v. Pendergrass, 878 F.2d 389, 400 (D.C. Cir. 1989)). 
OSHA ultimately decided to adopt an MRP provision for formaldehyde. 
However, as discussed below, the Agency did not rely on a need to 
protect employees permanently unable to return to their jobs. Indeed, 
OSHA expressly rejected that rationale for MRP, noting that ``[t]he MRP 
provisions [were] not designed to cover employees . . . determined to 
be permanently sensitized to formaldehyde'' (57 FR 22290, 22295 (5/27/
92)). An important objective of MRP is to prevent permanent health 
effects from developing by facilitating employee removal from exposure 
at a point when the effects are reversible, and that objective cannot 
be met where the effects are already permanent.
    Given that MRP benefits apply only to a temporary period, it is 
logical that eligibility be limited to employees with a temporary need 
for removal, as has been done in a number of standards, such as cadmium 
(1910.1027(l)(12)), benzene (1910.1028(i)(9)) and methylene chloride 
(1910.1052(j)(12)). Temporary wage and benefit protections may address 
the concerns of employees who fear temporary removal, but employees who 
fear permanent removal are unlikely to be persuaded by a few months of 
protection. The evidence in the record does not demonstrate that 
affected employees are unlikely to participate in medical surveillance 
absent wage and benefit protection. In contrast, extensive evidence in 
the record demonstrates that lack of confidentiality regarding medical 
findings would more likely lead to employees refusing medical 
examinations (e.g., Document ID 3577, Tr. 819-820; 3579, Tr. 169; 3581, 
Tr. 1657; 3585, Tr. 3053-3054); OSHA has remedied that situation by 
strengthening confidentially requirements for medical examinations.
    A major reason for inclusion of MRP in the formaldehyde standard is 
that medical surveillance depends on employee actions. The formaldehyde 
standard does not have a medical examination trigger, such as an action 
level, but instead relies on annual medical questionnaires and employee 
reports of signs and symptoms. Thus, the approach is completely 
dependent on employee cooperation (57 FR at 22293). Unlike the 
formaldehyde standard, respirable crystalline silica medical 
surveillance programs for the general industry/maritime and 
construction standards are not entirely dependent on employee reports 
of signs and symptoms. The respirable crystalline silica standard for 
general industry and maritime requires that regular medical 
examinations be offered to employees exposed at or above the action 
level for 30 or more days per year, and the construction standard 
requires that medical examinations be offered to employees required to 
wear a respirator for 30 or more days a year. Both standards mandate 
that those examinations include a physical examination, chest X-ray, 
and spirometry testing. Independent of any subjective symptoms that may 
or may not be reported by the employee, PLHCPs conducting these 
examinations can make necessary medical findings based on objective 
findings from the physical examination, X-ray, and spirometry tests.
    Lead is another example of a standard in which medical surveillance 
findings may be influenced by employee actions. In the lead standard, 
OSHA adopted an MRP provision in part due to evidence that employees 
were using chelating agents to achieve a rapid, short-term reduction in 
blood lead levels because they were desperate to avoid economic loss, 
despite the possible hazard to their health from the use of chelating 
agents. In the case of the lead standard, successful periodic 
monitoring of blood lead levels depends on employees not attempting to 
alter their blood lead levels (43 FR 54354, 54446 (11/21/78)).

[[Page 16840]]

Unlike the lead standard, in which blood lead levels are reported to 
employers, the respirable crystalline silica rule has privacy 
protections that do not allow information other than limitations on 
respirator use to be communicated to the employer, in the absence of 
employee authorization. With the privacy protections, it is unlikely 
that employees will try and take actions to sabotage medical findings.
    Other reasons OSHA has cited for needing to include MRP in its 
health standards are similarly inapplicable to respirable crystalline 
silica. In lead, for example, OSHA explained that the new blood lead 
level removal criteria for the lead standard were much more stringent 
than criteria being used by industry at that time. Therefore, many more 
temporary removals would be expected under the new standard, thereby 
increasing the utility of MRP (43 FR at 54445-54446). There are no 
criteria in this new rule that are likely to increase the number of 
medical removals that may be occurring.
    OSHA adopted MRP in the lead standard because it ``. . . 
anticipate[d] that MRP w[ould] hasten the pace by which employers 
compl[ied] with the new lead standard'' (43 FR at 54450). OSHA reasoned 
that the greater the degree of noncompliance, the more employees would 
suffer health effects necessitating temporary medical removal and the 
more MRP costs the employer would be forced to incur. OSHA thought that 
MRP would serve as an economic stimulus for employers to protect 
employees by complying with the standard. With respect to respirable 
crystalline silica, its disease outcomes (e.g., silicosis, COPD, lung 
cancer) generally take years to develop. Because of the latency period 
of most respirable crystalline silica-related diseases, the costs of 
MRP would not serve as a financial incentive for employers to comply 
with the requirements of the respirable crystalline silica rule. For 
example, most current high exposures would not result in adverse health 
effects until years later and most health effects requiring medical 
removal likely resulted from exposures that occurred years earlier, and 
in some cases, before the eligible employee worked for the current 
employer.
    In addition, although OSHA required medical removal in the benzene 
standard after referral to a specialist (1910.1028(i)(8)(i)), the 
circumstances there are also distinguishable from respirable 
crystalline silica. MRP was required in the benzene standard because 
some benzene-related blood abnormalities could rapidly progress to 
serious and potentially life threatening disease, and continued benzene 
exposure could affect progression (52 FR at 34555). With the exception 
of acute silicosis, which is rare, silica-related diseases progress 
slowly over a span of years. Thus, in most cases, there is no urgent 
need for removal from respirable crystalline silica exposure while 
awaiting a specialist determination.
    OSHA also notes that there are three health standards that provide 
limited MRP under their requirements for respiratory protection. They 
are asbestos, (1910.1001(g)(2)(iii)), cotton dust 
(1910.1043(f)(2)(ii)), and cadmium (29 CFR 1910.1027(l)(ii)). These 
standards require MRP when a medical determination is made that an 
employee who is required to wear a respirator is not medically able to 
wear the respirator and must be transferred to a position with 
exposures below the PEL, where respiratory protection is not required. 
OSHA has determined that such a provision is unnecessary for the 
respirable crystalline silica rule because OSHA has since revised its 
respiratory protection standard to specifically deal with the problem 
of employees who are medically unable to wear negative pressure 
respirators by requiring the employer to provide a powered air-
purifying respirator (29 CFR 1910.134(e)(6)). Such an approach has been 
used by employers who are unable to move employees to jobs with lower 
exposure (Document ID 3577, p. 610). In this rule, OSHA requires 
employers to comply with 29 CFR 1910.134, including medical evaluations 
mandated under that standard.
    In summary, OSHA finds MRP to be neither reasonably necessary nor 
appropriate for the respirable crystalline silica rule. In other health 
standards, OSHA has stated that the purpose of MRP is to encourage 
employees to participate in medical surveillance by assuring them that 
they will not suffer wage or benefit loss if they are temporarily 
removed from further exposure as a result of findings made in the 
course of medical surveillance. OSHA's primary reason for not including 
MRP in the respirable crystalline silica rule is that the Agency does 
not expect a significant number of employees to benefit from temporary 
removal from their jobs as a result of medical surveillance findings. 
In addition, the medical surveillance program in the respirable 
crystalline silica rule is less dependent on employee action that could 
influence medical surveillance findings than the programs in some other 
health standards that include MRP, such as lead and formaldehyde. Other 
considerations that have led OSHA to use MRP in the past are also not 
applicable in the context of respirable crystalline silica. OSHA 
expects that respirable crystalline silica-related health effects would 
result in very few temporary medical removals, and the evidence 
demonstrates that any removals that would occur would likely need to be 
permanent. OSHA concludes that the evidence in the record, relevant 
court decisions, and the criteria OSHA has previously applied to 
determine necessity for MRP do not support a finding that MRP is 
reasonably necessary or appropriate for the respirable crystalline 
silica rule.
    Requests for anti-discrimination/retaliation clause. Labor groups 
and other employee health advocates requested that OSHA add a clause to 
prohibit employers from retaliating or discriminating against employees 
for participating in medical surveillance or because of the findings of 
medical surveillance (e.g., Document ID 2176, p. 2; 2282, Attachment 3, 
p. 21; 2336, p. 12; 3577, Tr. 879; 3589, Tr. 4207; 4204, p. 90; 4219, 
pp. 33-36; 4223, p. 139). USW, BAC, and BCTD also requested that the 
anti-retaliation or anti-discrimination provisions address OSHA 
activities beyond medical surveillance (e.g., reporting unsafe working 
conditions), and in addition, BAC requested formal procedures for 
filing a complaint (Document ID 3584, Tr. 2548; 4219, pp. 33-38; 4223, 
p. 139). Employees, unions, and employee health advocates reported 
instances where employees were afraid to ask for protections or file 
complaints; some reported employer threats or retribution in response 
to such actions (e.g., Document ID 2124; 2173, p. 3; 3571, Attachment 
3, p. 2, Attachment 4, p. 3; 3577, Tr. 816-817; 3581, Tr. 1787, 1796; 
3583, Tr. 2464; 3584, Tr. 2567-2568; 3585, Tr. 3101; 3586, Tr. 3168).
    To address the possibility that some employees may decline to 
participate in medical surveillance because of fear of retaliation or 
discrimination, NISA suggested that OSHA require employee participation 
in medical surveillance, as well as include a prohibition on 
discrimination in the rule or clarify that Section 11(c) of the OSH Act 
applies to discrimination based on medical surveillance findings. NISA 
requested that OSHA at least confirm that employers are free to require 
medical surveillance as a condition of employment (Document ID 4208, 
pp. 15-18).
    As indicated in the NISA comments, Section 11(c) of the OSH Act 
prohibits discharge or discrimination against any

[[Page 16841]]

employee for exercising any right afforded by the Act (29 U.S.C. 
(660(c)(1)). OSHA observes that these rights include filing an OSHA 
complaint, participating in an inspection or talking to an inspector, 
seeking access to employer exposure and injury records, reporting an 
injury, and raising a safety or health complaint with the employer. 
Medical surveillance and the other requirements provided under the 
respirable crystalline silica rule are also rights afforded under the 
Act. Therefore, an employer may not discharge or otherwise discriminate 
against any employee because the employee participates in medical 
surveillance offered under the rule. This includes discharge or 
discrimination based on medical findings for an employee who is able to 
perform the essential functions of the job.
    Although acknowledging that the 11(c) protections are important 
because they establish that employees cannot be discriminated against 
for exercising their rights under the Act, Peg Seminario, on behalf of 
the AFL-CIO, stated that the enforcement mechanisms are very weak. Ms. 
Seminario pointed to the lack of an administrative process through the 
Review Commission, such as exists for compliance violations under 
standards, and she also stated that very few 11(c) cases are moved 
forward. In addition, Ms. Seminario testified that 11(c) deals with 
individual cases but does not address broad practices (Document ID 
3578, Tr. 981-982). BCTD pointed to testimony given by Professor Emily 
Spieler before a Senate Subcommittee on Employment and Workplace Safety 
that described weaknesses of 11(c) and gave recommendations for 
improving it (Document ID 4072, Attachment 27; 4223, p. 138). BCTD 
concluded that an anti-discrimination/retaliation provision might 
provide employees with ``an alternative, and potentially quicker, 
mechanism for gaining the Act's protections'' (Document ID 4223, p. 
139).
    OSHA recognizes that Section 11(c) of the Act has been an imperfect 
avenue for preventing retaliation and addressing employee complaints of 
discharge or discrimination for exercising rights afforded by the Act. 
For this reason, separate from this rulemaking, OSHA has made 
considerable efforts in recent years to enhance the effectiveness of 
its Section 11(c) program to protect employees from retaliation for 
exercising their rights under the OSH Act and other anti-retaliation 
statutes enforced by OSHA. These efforts include administrative 
restructuring to create a separate Directorate of Whistleblower 
Protection Programs as one of eight Directorates in OSHA; adding 
additional investigators; and providing additional training for 
investigators and Labor Department solicitors who work on whistleblower 
cases. The Agency's Whistleblower Investigations Manual updated 
procedures and provided further guidance to help ensure consistency and 
quality of investigations (see https://www.osha.gov/OshDoc/Directive_pdf/CPL_02-03-005.pdf), and OSHA's memo to whistleblower 
enforcement staff on Employer Safety Incentive and Disincentive 
Policies and Practices, clarified that employer policies that 
discourage reporting of injuries and illnesses constitute violations of 
section 11(c) (see https://www.osha.gov/as/opa/whistleblowermemo.html). 
In addition, the Department of Labor has established a Whistleblower 
Protection Advisory Committee to advise, consult with, and make 
recommendations to the Secretary of Labor and the Assistant Secretary 
of Labor for Occupational Safety and Health on ways to improve the 
fairness, efficiency, effectiveness, and transparency of OSHA's 
administration of whistleblower protections (77 FR 29368 (5/17/12)). 
OSHA concludes that the Agency's limited resources will be best 
utilized by continuing to focus on strengthening enforcement of Section 
11(c), rather than creating, on an ad hoc basis, a separate and 
alternative enforcement mechanism in the respirable crystalline silica 
rule. OSHA emphasizes that, in response to commenters' concerns about 
privacy and the possibility for retaliation based on employers' 
knowledge of employee medical information, it has made changes to the 
medical surveillance disclosure requirements of the rule, discussed 
above, in order to both encourage participation in medical surveillance 
and discourage discriminatory or retaliatory actions. Retaliation based 
on other activities, such as reporting injuries and illnesses or noting 
the failure of engineering controls, is not unique to the silica rule 
and thus does not, in OSHA's judgment, warrant a silica-specific 
response.
    In response to the suggestion that OSHA prohibit employees from 
opting out of medical surveillance, OSHA observes that Section 
(6)(c)(7) of the OSH Act specifies that medical examinations or other 
tests ``be made available,'' not that they be required. OSHA considers 
the medical surveillance offered under the rule to offer important 
protections for employees, and the Agency encourages all eligible 
employees to take advantage of these protections. However, the Agency 
recognizes that employees may choose not to take advantage of medical 
surveillance for a variety of reasons. OSHA does not find it 
appropriate to require all eligible employees to receive medical 
surveillance simply to preclude the possibility that an employer might 
discriminate against those who receive medical surveillance. The Agency 
also notes that Section 20(a)(5) of the OSH Act generally precludes 
OSHA from requiring medical surveillance for those who object on 
religious grounds. At the same time, nothing in the rule precludes an 
employer from requiring participation in medical surveillance programs 
as appropriate under applicable laws and/or labor-management contracts.
    ASTM standards. Most medical surveillance requirements in the 
respirable crystalline silica rule are generally consistent with ASTM 
standards for addressing control of occupational exposure to respirable 
crystalline silica (Section 4.6 and 4.7 in both E 1132-06 and E 2625-
09) (Document ID 1466, p. 5; 1504, p. 5). Commenters noted differences 
between the ASTM standards and the respirable crystalline silica rule 
(i.e., 120- versus 30-day exposure duration trigger, optional versus 
mandatory spirometry testing, and referrals based on a 1/1 versus 1/0 
category X-ray). As explained above, the requirements of the rule 
better protect employees and therefore better effectuate the purposes 
of the OSH Act than the ASTM standards. There are additional 
differences between the ASTM standards and the rule, which are 
discussed briefly below.
    The ASTM standards require that medical surveillance be triggered 
by the PEL or other occupational exposure limit, but for the general 
industry and maritime standard, OSHA is triggering medical surveillance 
at the action level because of remaining significant risk, exposure 
variability, and increased sensitivity of some employees. The ASTM 
standards recommend medical examinations before placement but OSHA 
allows the examinations to be conducted within 30 days to offer more 
flexibility.
    The ASTM standards recommend tuberculosis testing for employees 
with radiographic evidence of silicosis, but the rule requires 
tuberculosis testing in the initial examination for all employees who 
qualify for medical surveillance. OSHA's requirement is based on 
evidence that exposure to respirable crystalline silica increases the 
risk for a latent tuberculosis infection becoming active, even in the 
absence of silicosis. The ASTM standards do not specifically

[[Page 16842]]

mention a specialist, but the requirement for specialist referral in 
the respirable crystalline silica rule is conceptually consistent with 
the provision in the ASTM standards for counseling (by a physician or 
other person qualified in occupational safety and health) regarding 
work practices and personal habits that could affect employees' 
respiratory health.
    Lastly, the E 1132-06 standard allows the health provider to report 
information to the employer, such as if the employee has a condition 
that might put him or her at risk for health impairment or if 
limitations on respirator use are related to medical or emotional 
reasons. Under the rule for respirable crystalline silica, medical 
findings are withheld from the employer and only reported to the 
employee because of privacy concerns and discrimination/retaliation 
fears that might prevent participation in medical surveillance. Both 
ASTM standards require the employer to follow the physician's placement 
or job assignment recommendations; the OSHA rule differs from the ASTM 
standards in this respect by allowing employees to make their own 
placement decisions if they are able to do the work.

Communication of Respirable Crystalline Silica Hazards to Employees

    Paragraph (j) of the standard for general industry and maritime 
(paragraph (i) of the standard for construction) sets forth 
requirements intended to ensure that the dangers of respirable 
crystalline silica exposure are communicated to employees. Employees 
need to know about the hazards to which they are exposed, along with 
associated protective measures, in order to understand how they can 
minimize potential health hazards. As part of an overall hazard 
communication program, training serves to explain and reinforce the 
information presented on labels and in safety data sheets (SDSs). These 
written forms of communication will be effective and relevant only when 
employees understand the information presented and are aware of the 
actions to be taken to avoid or minimize exposures, thereby reducing 
the possibility of experiencing adverse health effects. Numerous 
commenters, including industry stakeholders and dozens of construction 
employees and concerned individuals, generally supported inclusion of a 
hazard communication requirement in the rule (e.g., Document ID 2039; 
2113; 2116, Attachment 1, p. 45; 2302, p. 1; 2315, p. 4; 2345, p. 3; 
3302, p. 1; 3295; 4217, p. 25).
    Paragraph (j)(1) of the standard for general industry and maritime 
(paragraph (i)(1) of the standard for construction) requires the 
employer to (1) include respirable crystalline silica in the program 
established to comply with the hazard communication standard (HCS) (29 
CFR 1910.1200); (2) ensure that each employee has access to labels on 
containers of crystalline silica and SDSs, and is trained in accordance 
with the provisions of the HCS and the provisions on employee 
information and training (contained in paragraph (j)(3) of the standard 
for general industry and maritime, paragraph (i)(2) of the standard for 
construction), and (3) ensure that at least the following hazards are 
addressed: Cancer, lung effects, immune system effects, and kidney 
effects. These requirements remain unchanged from the proposed rule, 
after OSHA considered comments addressing these requirements (discussed 
below).
    The approach in paragraph (j)(1) of the standard for general 
industry and maritime (paragraph (i)(1) of the standard for 
construction) is consistent with other OSHA substance-specific health 
standards, which were revised as part of the 2012 update of the HCS to 
conform to the United Nations' Globally Harmonized System of 
Classification and Labelling of Chemicals (GHS). The 2012 update of the 
substance-specific standards involved revising the hazard communication 
requirements to refer to the HCS requirements for labels, SDSs, and 
training, and to identify the hazards that need to be addressed in the 
employer's hazard communication program for each substance-specific 
standard. In applying the approach described in paragraph (j)(1) of the 
standard for general industry and maritime (paragraph (i)(1) of the 
standard for construction), OSHA intends for the hazard communication 
requirements in the respirable crystalline silica rule to be 
substantively as consistent as possible with the HCS, while including 
additional specific requirements needed to protect employees exposed to 
respirable crystalline silica. A goal of this approach is to avoid a 
duplicative administrative burden on employers who must comply with 
both the HCS and this rule.
    Some stakeholders agreed with OSHA that additional hazard 
communication provisions are needed in this rule. For example, the 
National Industrial Sand Association (NISA) generally agreed with 
OSHA's approach for communication of hazards to employees and indicated 
that the generic training elements of the HCS alone are insufficient 
(Document ID 2195, p. 45). In addition, labor unions such as the United 
Automobile, Aerospace and Agricultural Implement Workers of America 
(UAW), International Union of Operating Engineers (IUOE), American 
Federation of Labor and Congress of Industrial Organizations (AFL-CIO), 
International Union of Bricklayers and Allied Craftworkers (BAC), and 
Building and Construction Trades Department, AFL-CIO (BCTD) generally 
agreed that employees exposed to respirable crystalline silica need 
additional information and training (Document ID 2282, Attachment 3, p. 
24; 3583, Tr. 2367; 4204, p. 98; 4219, p. 22; 4223, p. 114).
    However, other stakeholders expressed the view that OSHA's existing 
HCS requirements are sufficient, and that hazard communication 
provisions in this rule are not warranted. For example, the National 
Stone, Sand, and Gravel Association (NSSGA) asserted that requiring 
information and training under the respirable crystalline silica rule 
would be duplicative and unnecessary because OSHA's existing HCS 
adequately addresses communication of hazards and training of employees 
(Document ID 2327, Attachment 1, p. 11). The Portland Cement 
Association and National Association of Home Builders (NAHB) expressed 
similar views (Document ID 2284, p. 6; 2296, p. 44).
    OSHA understands that the HCS already addresses communication of 
hazards but, after reviewing rulemaking record comments, reaffirms that 
employees exposed to respirable crystalline silica need additional 
training and information. Therefore, OSHA has decided to include in the 
rule the approach set forth in the proposed rule. The rule thus 
requires compliance with the HCS and the additional requirements that 
address aspects of employee protection that are not specified in the 
HCS but are relevant to these standards; examples of these provisions 
include health hazards specific to respirable crystalline silica, signs 
at entrances to regulated areas, training on medical surveillance, and 
training on engineering controls. Specific comments on these 
requirements and OSHA's rationale for their inclusion in the rule are 
discussed below. OSHA expects this approach will reduce the 
administrative burden on employers who must comply with both the HCS 
and this rule, while providing employees with adequate information and 
effective training on respirable crystalline silica hazards.
    Which hazards should be addressed in employers' HCS programs was a

[[Page 16843]]

matter of debate among commenters. For example, the American Coatings 
Association (ACA) asserted that OSHA's listing of health effects 
associated with crystalline silica was contrary to the revised HCS, 
which ACA argued allows qualified health professionals to established 
hazard classifications based on actual data (Document ID 2239, p. 2). 
Associated Builders and Contractors, Inc. and the Construction Industry 
Safety Coalition (CISC) did not support the inclusion of cancer, immune 
system effects, and kidney effects on the list of hazards to be 
addressed, asserting that OSHA did not meet its burden of showing a 
link between these diseases and exposure to crystalline silica 
(Document ID 2289, p. 8; 2319, p. 120).
    OSHA does not find these arguments persuasive. As discussed in 
Section V, Health Effects, OSHA evaluated the best available published, 
peer-reviewed literature on respirable crystalline silica and 
considered comments from stakeholders to determine that exposure to 
respirable crystalline silica is associated with silicosis and other 
non-malignant respiratory disease, lung cancer, immune system effects, 
and kidney effects. Inclusion of a minimum list of health effects to 
address as part of hazard communication, based primarily on information 
from OSHA's rulemakings, is consistent with the 2012 revision of all 
substance-specific standards (77 FR 17574, 17749-17751, 17778-17785 (3/
26/2012)). Therefore, the Agency concludes that including a list of 
hazards to be addressed, and the specific hazards listed, are 
appropriate.
    Commenters such as the United Steelworkers (USW) and the American 
Federation of State, County, and Municipal Employees (AFSCME) requested 
that the rule require training on tuberculosis (Document ID 2336, pp. 
14-15; 4203, p. 7). OSHA did not specifically list tuberculosis as a 
health hazard to be addressed because initial tuberculosis infection is 
not related to respirable crystalline silica exposure. In addition, the 
HCS describes health hazards in terms of target organs affected, such 
as lungs, or specific endpoints, such as carcinogenicity. Tuberculosis 
is not an endpoint listed in the HCS; thus, listing it in this rule 
would be inconsistent with the HCS. Consequently, OSHA has decided not 
to add tuberculosis to the list of hazards that must be addressed. 
However, because respirable crystalline silica exposure increases the 
risk of a latent tuberculosis infection becoming active, OSHA 
encourages employers to address tuberculosis as part of their hazard 
communication program.
    Paragraph (j)(2) of the standard for general industry and maritime 
requires employers to post signs at all entrances to regulated areas. 
Although OSHA proposed a requirement for demarcating regulated areas, 
the Agency did not propose a requirement for warning signs at entrances 
to regulated areas, and instead noted that the areas could be 
effectively demarcated by signs, barricades, lines, or textured 
flooring (78 FR at 56273, 56450 (9/12/13)). The AFL-CIO argued that 
warning signs are an important method of making employees aware of 
potential hazards and noted that warning signs are required at 
entrances to regulated areas by many OSHA standards (Document ID 4204, 
pp. 100-101). A number of commenters, including the Communication 
Workers of America (CWA), Upstate Medical University, the American 
Public Health Association (APHA), UAW, and HalenHardy, agreed that 
warning signs must be required at regulated areas (e.g., Document ID 
2240, p. 4; 2244, p. 4; 2178, Attachment 1, p. 2; 2282, Attachment 3, 
p. 25; 4030, Exhibit A, pp. 5-6). Similarly, USW commented on the need 
for warning signs in areas with potential respirable crystalline silica 
exposure (Document ID 2336, p. 14). Charles Gordon, a retired 
occupational safety and health attorney, argued that the absence of a 
requirement for warning signs was inconsistent with Section 6(b)(7) of 
the Occupational Safety and Health (OSH) Act, which requires labels or 
other warnings to inform employees of hazards (Document ID 3588, Tr. 
3797). Evidence in the rulemaking record indicates that inclusion of 
warning signs is also consistent with general industry practices. For 
example, a plan developed by the National Service, Transmission, 
Exploration, and Production Safety Network (STEPS Network) for the 
hydraulic fracturing industry recommends signs to warn of potential 
silica exposure and the requirement for respirator use near exposure 
zones (Document ID 4024, Attachment 2, p. 1).
    OSHA finds these arguments persuasive and agrees that it is 
appropriate to require signs at entrances to regulated areas, which are 
required only in the general industry and maritime standard (see 
summary and explanation for Regulated Areas). Employees must recognize 
when they are entering a regulated area and understand the hazards 
associated with the area, as well as the need for respiratory 
protection. Signs are an effective means of accomplishing these 
objectives. Therefore, paragraph (j)(2) of the standard for general 
industry and maritime requires that regulated areas be posted with 
signs that bear the exact cautionary wording specified in the standard. 
The required legend, which begins with the word ``Danger'', warns that 
respirable crystalline silica is present and may cause cancer, states 
that it causes damage to lungs, states that respiratory protection is 
required, and indicates authorized personnel only are permitted to 
enter. The purpose of these signs is to minimize the number of 
employees in a regulated area by alerting them that they must be 
authorized by their employer to enter, and to ensure that employees 
take appropriate protective measures when entering. The signs will warn 
employees who may not know they are entering a regulated area or may 
not know of the hazards present in the area. They will supplement the 
training that employees are to receive under other provisions of 
paragraph (j) of the standard for general industry and maritime because 
even trained employees need to be reminded of the locations of 
regulated areas and of the necessary precautions they must take before 
entering these dangerous areas.
    The required language for the signs is consistent with labeling 
requirements in Appendix C of the HCS, which specifies standardized 
language to communicate information to employees. The revised HCS 
requires the use of one of two signal words--``Danger'' or 
``Warning''--on labels of hazardous chemicals. The word ``Danger'' is 
used for more severe hazard categories, such as carcinogens. OSHA is 
requiring the word ``Danger'' based on the evidence of lung toxicity 
and carcinogenicity of respirable crystalline silica. ``Danger'' is 
used to alert employees that they are in an area where the permissible 
exposure limit (PEL) is or can reasonably be expected to be exceeded 
and to emphasize the importance of the message that follows.
    Charles Gordon requested that warning signs also warn about kidney 
hazards (Document ID 4236, p. 6). The hazard statements about cancer 
and lung damage required on signs are the minimum requirements and 
focus on the most prominent adverse health effects associated with 
respirable crystalline silica exposure. OSHA concludes that it is 
unnecessary to list every relevant hazard warning on signs at entrances 
to regulated areas because other sources of information, such as SDSs 
and training, will provide more comprehensive information to employees. 
In addition, addressing cancer and lung damage is conceptually 
consistent with specific wording

[[Page 16844]]

suggestions from APHA, National Consumers League, BCTD, HalenHardy, and 
AFL-CIO (Document ID 2178, Attachment 1, pp. 2-3; 2373, p. 2; 2371, 
Attachment 1, pp. 36-37; 4030, Exhibit D; 4204, p. 101). Including an 
abbreviated list of health hazards on signs is also consistent with 
other OSHA standards such as lead (29 CFR 1910.1025), benzene (29 CFR 
1910.1028), and vinyl chloride (29 CFR 1910.1017). Therefore, OSHA has 
decided not to add a requirement to include warnings about kidney 
hazards on warning signs. Employers may choose to include a warning 
about kidney hazards on the signs required under this standard, 
provided that the additional information included is not confusing or 
misleading and does not detract from warnings required by the standard.
    The warning sign must include notice about the need for respiratory 
protection in regulated areas required under the general industry and 
maritime standards. As explained in the summary and explanation of 
Regulated Areas, employers covered by the standard for general industry 
and maritime are required to provide each employee and his or her 
designated representative entering a regulated area with an appropriate 
respirator and require the employee and designated representative to 
use the respirator while in the regulated area. APHA, National 
Consumers League, and Charles Gordon requested that warning signs also 
indicate that protective clothing is required (Document ID 2178, 
Attachment 1, p. 3; 2373, p. 2; 4236, p. 6). As discussed in the 
summary and explanation of Regulated Areas, protective clothing is not 
required in this rule, and therefore no corresponding notice is 
required on signs.
    Some labor unions that represent construction employees, such as 
BCTD, IUOE, and BAC, asked OSHA to include requirements for warning 
signs in the construction standard to warn employees about health 
hazards or requirements for control measures (e.g., Document ID 2371, 
Attachment 1, pp. 36-37; 4025, Attachment 1, pp. 24-25; 4219, p. 27). 
Some employers, like construction company Miller and Long, Inc., 
opposed requiring barricades and signs at construction sites (e.g., 
Document ID 3585, Tr. 2967).
    As discussed in the summary and explanation of Regulated Areas, 
OSHA is not requiring regulated areas in the standard for construction 
because of the impracticality of establishing regulated areas in many 
construction settings. Employers using specified exposure control 
methods in Table 1 of paragraph (c) of the standard for construction 
are not required to conduct exposure assessments and therefore will not 
have the information necessary to establish the boundaries for the 
regulated area (i.e., the point at which exposures would no longer 
exceed the PEL). Even though regulated areas with warning signs are not 
required for the construction standard, the employer may choose to 
include procedures for posting warning signs in its written exposure 
control plan as a method to restrict access to work areas, when 
necessary, to limit the numbers of employees exposed to respirable 
crystalline silica and the levels to which they are exposed, including 
exposures generated by other employers or sole proprietors (paragraph 
(g)(1)(iv) of the standard for construction). Because of the unique and 
often-changing work areas at construction sites, OSHA concludes that a 
universal requirement for regulated areas with signs is unwarranted, 
and the construction employer is in the best position to determine when 
warning signs should be posted.
    IUOE requested a requirement to affix warning labels listing the 
health hazards of respirable crystalline silica on enclosed cabs to 
remind operators not to work with windows open (Document ID 2262, pp. 
34-35). Where enclosed cabs are used to limit exposures to respirable 
crystalline silica, the employer must ensure that these controls are 
properly implemented (paragraph (c)(1) of the standard for 
construction) and that employees can demonstrate knowledge of the 
controls (paragraph (i)(2)(i)(C) of the standard for construction). 
Therefore, OSHA concludes that a general requirement to affix warning 
labels to cabs is unwarranted and construction employers are in the 
best position to determine if there is a need for warning labels in 
their workplaces as a reminder to properly implement controls. As a 
result, OSHA has not included such a requirement in the standard.
    Proposed paragraph (i)(2)(i) included the requirements related to 
employee information and training. The proposed rule called for the 
employer to ensure that each ``affected employee'' can demonstrate 
knowledge of the specified training elements discussed below. OSHA 
defined ``affected employee'' as any employee who may be exposed to 
respirable crystalline silica under normal conditions of use or in a 
foreseeable emergency. OSHA received several comments related to a 
trigger for training requirements. For example, the American Iron and 
Steel Institute (AISI) commented that the terms ``each employee'' and 
``each affected employee'' were used interchangeably in the proposed 
rule and that OSHA needed to clarify which employees needed to receive 
training; both Newport News Shipbuilding and AISI commented that 
training should be limited to those employees who could foreseeably be 
exposed above the PEL (Document ID 2144, p. 2; 3492, p. 3). Southern 
Company was concerned that training would be required for all employees 
potentially exposed to silica, and although disagreeing with an action 
level of 25 micrograms per cubic meter of air ([mu]g/m\3\), requested 
an action level-based trigger for training (Document ID 2185, p. 5). In 
contrast, CISC supported training for all employees potentially exposed 
to respirable crystalline at a construction site (Document ID 4217, p. 
25). A number of other employers and industry representatives expressed 
views on exposure levels that should trigger training, such as action 
levels or PELs (e.g., Document ID 2196, Attachment 1, p. 11; 2279, p. 
9; 2301, Attachment 1, p. 4; 2357, pp. 31-32; 2379, Appendix 1, p. 54). 
BCTD requested that, in addition to employees performing work covered 
by this section, OSHA require training for supervisors and on-site 
managers who are responsible for, or who supervise, employees who 
perform work covered by the standard (Document ID 4223, p. 117).
    OSHA has clarified the trigger for training requirements in the 
rule by aligning these requirements with the scope of the rule. 
Paragraph (j)(3)(i) of the standard for general industry and maritime 
(paragraph (i)(2)(i) of the standard for construction) requires 
training for each employee covered by the rule. Consistent with the 
scope provision in paragraph (a)(2) of the standard for general 
industry and maritime, training is required for each employee, unless 
the employer has objective data demonstrating that exposures will 
remain below 25 [mu]g/m\3\ as an 8-hour time-weighted average under any 
foreseeable conditions. Consistent with the scope provision in 
paragraph (a) of the standard for construction, training is required 
for all employees who are or could foreseeably be exposed to respirable 
crystalline silica at or above the action level of 25 [mu]g/m\3\ as an 
8-hour time-weighted average. Therefore, actual or foreseeable exposure 
at or above the action level is used to determine which employees are 
covered by the rule, and covered employers are required to provide 
training for any employee covered by

[[Page 16845]]

the rule. OSHA concludes that it is appropriate to train employees 
covered by the rule because they will benefit from receiving 
information such as the role of controls in reducing exposures and 
illnesses associated with respirable crystalline silica.
    Stakeholders also offered comments on the proposed requirement that 
employers ensure that affected employees can ``demonstrate knowledge'' 
of the training subjects in proposed paragraphs (i)(2)(i)(A)-(D). The 
proposed rule did not specify precisely how training should be 
accomplished. Instead, it defined the hazard communication requirements 
in terms of objectives meant to ensure that employees are made aware of 
the hazards associated with respirable crystalline silica in their 
workplace and how they can help to protect themselves. The proposed 
rule's performance-oriented approach was consistent with the HCS and 
many of OSHA's substance-specific standards.
    Some stakeholders commented on OSHA's performance-based approach to 
training. For example, Diane Matthew Brown, Health and Safety 
Specialist from AFSCME, testified that training should be as 
interactive as possible to allow for different learning styles 
(Document ID 3585, Tr. 3115). CISC supported the performance-oriented 
approach to training but also stated it would support a requirement 
that employees be able to ask questions during training (Document ID 
4217). IUOE recommended interactive training so that employees could 
have their questions answered during the training (Document ID 3583, 
Tr. 2369). Although agreeing with the importance of a knowledgeable 
person to answer trainee questions, Ameren Corporation considered it 
burdensome to have someone immediately available to answer questions 
(Document ID 2315, p. 4). The Laborers' Health and Safety Fund of North 
America (LHSFNA) indicated that hands-on training is the best approach 
to training an employee who performs tasks that generate dust in the 
proper operation of a tool and associated engineering controls 
(Document ID 3589, Tr. 4220-4221).
    After considering the comments on this issue, OSHA has decided that 
the training requirements under the respirable crystalline silica rule, 
like those in the HCS, are best accomplished when they are performance-
oriented. OSHA concludes that the employer is in the best position to 
determine how the training can most effectively be accomplished. Hands-
on training, videotapes, slide presentations, classroom instruction, 
informal discussions during safety meetings, written materials, or any 
combination of these methods may be appropriate. However, to ensure 
that employees comprehend the material presented during training, it is 
critical that trainees have the opportunity to ask questions and 
receive answers if they do not fully understand the material that is 
presented to them. OSHA reiterates that when videotape presentations or 
computer-based programs are used, this requirement may be met by having 
a qualified trainer available to address questions after the 
presentation, or providing a telephone hotline so that trainees will 
have direct access to a qualified trainer. Although it is important 
that employees be able to ask questions, OSHA finds that the employer 
is in the best position to determine whether an instructor must be 
available for questions during training or if a trainer can answer 
questions after the training session. Such performance-oriented 
requirements are intended to encourage employers to tailor training to 
the needs of their workplaces, thereby resulting in the most effective 
training program for each workplace.
    In addition to asking about how training should be accomplished, 
stakeholders posed questions about how employers can determine that 
they have fulfilled the training requirements. For example, the 
American Foundry Society stated that the term ``demonstrate knowledge'' 
is vague and requested that the rule include language to specify when a 
training requirement is met (Document ID 2379, Appendix 1, p. 72). OSHA 
concludes that employers can determine whether employees have the 
requisite knowledge through methods such as discussion of the required 
training subjects, written tests, or oral quizzes. Retired industrial 
hygienist Bill Kojola, testifying on behalf of the National Council for 
Occupational Safety and Health (NCOSH), suggested that compliance 
officers could question employees to determine if they know about 
medical surveillance and work practices or engineering controls to 
reduce exposures (Document ID 3586, Tr. 3259). Similarly, UAW 
coordinator, Andrew Comai, and a private citizen, Cara Ivens, opined 
that compliance officers could ask employees if they are aware that 
they are working with hazardous chemicals or know about the health 
effects of respirable crystalline silica (Document ID 1801, p. 4; 3582, 
Tr. 1869). OSHA concludes that employers can similarly assess their 
employees' knowledge and understanding of training topics.
    The proposed rule did not include a provision that required 
training to be conducted in a language and manner that the employee 
understands. A number of labor unions and employee advocate groups 
requested that the rule include a requirement for training to be 
conducted in a language and manner that employees understand (e.g., 
Document ID 2240, p. 4; 2282, Attachment 3, p. 25; 3585, Tr. 3115; 
3955, Attachment 2, p. 2; 3583, Tr. 2451; 4204, p. 99; 4025, Attachment 
1, p. 2; 4219, p. 24).
    OSHA agrees. Paragraph (j)(3)(i) of the standard for general 
industry and maritime (paragraph (i)(2)(i) of the standard for 
construction) requires the employer to ensure that each employee 
covered by the standard demonstrates knowledge and understanding of the 
required training subjects. The requirement for employers to ensure 
that the employee demonstrates knowledge in the training subjects 
obligates the employer to provide training in a language and manner 
that the employee understands. The employee must understand training in 
order to demonstrate knowledge of the specified training elements. To 
clarify this requirement, OSHA has revised the proposed text to require 
the employer to ensure that employees demonstrate understanding, in 
addition to knowledge. This requirement is consistent with Assistant 
Secretary David Michaels' memorandum to OSHA Regional Administrators 
(Document ID 1499). The memorandum explains that because employees have 
varying educational levels, literacy, and language skills, training 
must be presented in a language, or languages, and at a level of 
understanding that accounts for these differences in order to ensure 
that employees understand the training. As stated by Assistant 
Secretary Michaels:

. . . an employer must instruct its employees using both a language 
and vocabulary that the employees can understand. For example, if an 
employee does not speak or comprehend English, instruction must be 
provided in a language that the employee can understand. Similarly, 
if the employee's vocabulary is limited, the training must account 
for that limitation. By the same token, if employees are not 
literate, telling them to read training materials will not satisfy 
the employer's training obligation (Document ID 1499, p. 2).

    This may mean, for example, providing materials, instruction, or 
assistance in Spanish rather than English if the employees being 
trained are Spanish-speaking and do not understand English. However, 
the employer is not required to provide

[[Page 16846]]

training in the employee's preferred language if the employee 
understands the language used for training.
    Proposed paragraphs (i)(2)(i)(A)-(D) specified the contents of 
training for affected employees. The proposed list included training on 
operations that could result in exposures and methods for protecting 
employees from exposure, the contents of the respirable crystalline 
silica rule, and the purpose and a description of the employer's 
medical surveillance program. The proposed rule did not contain a 
provision requiring training on health effects. However, under the HCS, 
employers would have to train employees on the health hazards 
associated with chemicals in the work area (29 CFR 
1910.1200(h)(3)(ii)). In addition, the preamble to the proposed rule 
mentioned that training on medical surveillance under proposed 
paragraph (i)(2)(i)(D) should cover the signs and symptoms of 
respirable crystalline silica-related health effects (78 FR at 56474).
    OSHA asked for comments on the scope and depth of the proposed 
training requirements and whether additional training provisions needed 
to be added (78 FR at 56291). Stakeholders offered a number of comments 
on these proposed provisions. For example, concerned individuals, a 
medical school, and labor unions requested that training address the 
health effects associated with respirable crystalline silica exposure 
(e.g., Document ID 1771, p. 1; 2188; 3479, p. 1; 4025, Attachment 1, p. 
2; 4203, p. 7). Training on health hazards of respirable crystalline 
silica is consistent with stakeholder practices. For example, health 
hazards are addressed in training plans or modules by the National 
Precast Concrete Association, IUOE, and the STEPS Network (e.g., 
Document ID 2067, pp. 2-3; 3583, Tr. 2414; 4024, Attachment 2, p. 1).
    Several commenters stated that employees would not ask for or use 
appropriate protection without knowledge of health hazards (e.g., 
Document ID 2166, p. 3; 3571, Attachment 1, pp. 2-3, 3585, Tr. 2976). 
For example, in discussing her experience with overhead drilling of 
concrete, Sandra Darling-Roberts commented:

    I had a dust mask and a pair of safety glasses for my 
protection. . . . We were not offered better personal protection 
gear and did not request any as we were not made aware of the risks 
of silica exposure (Document ID 1758).

    Operating engineer Keith Murphy, representing IUOE, testified that 
employees will wear respirators if informed that they are exposed to 
dangerous concentrations of respirable crystalline silica (Document ID 
3583, Tr. 2375-2376). In testifying about her experiences in training 
construction employees, Mari[eacute]n Casillas Pabell[oacute]n, 
Director of New Labor, stated:

    [Seventy percent] of these workers were not able to say what 
silica was or if they were . . . exposed to it. When they learned 
about the long term effects to their health many were alarmed. 
Training has been key in getting workers to demand . . . the right 
equipment and tools to complete their task safely. Always after 
trainings we follow up with the participants to measure the impact 
of the trainings. [Fifty-five percent] of the workers that received 
training around these issues expressed that they have demanded 
personal protective equipment and other tools to do their work 
safely after the training (Document ID 3571, Attachment 6, p. 2).

In addition, several employees indicated that neither they nor their 
coworkers had received adequate or even any training on silica's health 
effects (e.g., Document ID 3582, Tr. 1892-1893; 3589, Tr. 4299-4300; 
4032, Attachment 1, p. 1; 3477, p. 1).
    Based on the evidence showing the need for and positive impact of 
health hazard training and to ensure that covered employees receive 
that training, OSHA is requiring training on health hazards 
specifically associated with respirable crystalline silica. The 
requirement is contained in paragraph (j)(3)(i)(A) of the standard for 
general industry and maritime (paragraph (i)(2)(i)(A) of the standard 
for construction).
    Proposed paragraph (i)(2)(i)(A) required that employees be trained 
on specific operations in the workplace that could result in exposure 
to respirable crystalline silica, especially operations where exposures 
may exceed the PEL. BCTD recommended that ``tasks'' rather than 
``operations'' be used, because operations could include various tasks; 
it also requested that OSHA remove the statement ``especially 
operations where exposure may exceed the PEL'' (Document ID 2371, 
Attachment 1, pp. 23, 35). OSHA agrees that ``tasks'' is the more 
appropriate term. The Agency also agrees that employers and employees 
must understand all sources of potential respirable crystalline silica 
exposure and, therefore, removed the phrase ``especially operations 
where exposure may exceed the PEL.'' Therefore, OSHA has revised the 
proposed language so that paragraph (j)(3)(i)(B) of the standard for 
general industry and maritime (paragraph (i)(2)(i)(B) of the 
construction standard) now requires training on specific workplace 
tasks that could result in exposure to respirable crystalline silica.
    Proposed paragraph (i)(2)(i)(B) required that employees be trained 
on procedures implemented by the employer to protect them from 
respirable crystalline silica exposure, including appropriate work 
practices and use of personal protective equipment (PPE), such as 
respirators and protective clothing. Labor unions and employee advocate 
groups, such as CWA, UAW, USW, NCOSH, AFSCME, IUOE, and BCTD, requested 
that OSHA also specify training on engineering controls (Document ID 
2240, p. 4; 2282, Attachment 3, p. 24; 2336, p. 15; 3955, Attachment 2, 
p. 2; 4203, p. 7; 4025, Attachment 1, p. 2; 4223, p. 118). The value of 
training on engineering controls is demonstrated by the testimony of 
construction employee and New Labor Safety Liaison, Norlan Trejo, who 
stated that because of his training, he is aware of the types of 
engineering controls needed on job sites and he requests such controls 
if the employer does not provide them (Document ID 3583, Tr. 2462-
2463).
    Because engineering controls are a vital aspect of reducing 
exposures, OSHA has concluded that employees covered by this rule must 
understand how they work in order to use the appropriate work practices 
to fully and properly implement those controls and to be able to 
recognize if engineering controls are malfunctioning. Therefore, OSHA 
has revised the proposed provision to also require training on 
engineering controls. OSHA has also removed the term ``appropriate'' 
because it is implicit that any work practice or other methods used to 
protect employees be appropriate. In addition, ``personal protective 
equipment'' and ``protective clothing'' were removed from the paragraph 
because respirators are the only type of PPE required by the rule. 
Thus, paragraph (j)(3)(i)(C) of the standard for general industry and 
maritime (paragraph (i)(2)(i)(C) of the standard for construction) 
requires training on specific measures implemented by the employer to 
protect employees from respirable crystalline silica exposure, 
including engineering controls, work practices, and respirators to be 
used.
    Several labor unions that represent employees in the construction 
industry highlighted additional training that they thought necessary 
for some construction employees. For example, BCTD requested that OSHA 
establish tiered training requirements in the construction standard to 
include: (1) Basic awareness training for all

[[Page 16847]]

employees potentially exposed to respirable crystalline silica, (2) 
additional equipment-specific training for employees who perform tasks 
that generate respirable crystalline silica, and (3) training for a 
competent person. BCTD noted that similar approaches were taken in 
other OSHA standards, such as asbestos (29 CFR 1926.1101(k)(9)) 
(Document ID 4223, pp. 114, 116-117). The tiered approach to training 
recommended by BCTD was also supported by IUOE, LHSFNA, and BAC 
(Document ID 3583, Tr. 2367-2368; 4207, p. 5; 4219, pp. 22-24).
    In supporting a tiered approach, BCTD noted ``the effectiveness of 
the standard and the engineering controls used to limit silica exposure 
depend heavily on how the controls are used.'' (Document ID 4223, p. 
117). Dr. Paul Schulte, Director of the Education and Information 
Division at the National Institute for Occupational Safety and Health, 
testified that engineering controls listed in Table 1 are only 
effective if they are maintained and employees are trained on their 
correct use (Document ID 3403, p. 6). Similar views regarding training 
and effectiveness of controls were expressed by Joel Guth, President of 
iQ Power Tools, Bill Kojola, and Tom Nunziata, instructor/training 
coordinator for LHSFNA; Mr. Nunziata also noted the importance of 
hands-on training (Document ID 3585, Tr. 2982-2983; 3586, Tr. 3204-
3206; 3589, Tr. 4220-4221).
    Evidence in the record further demonstrates knowledge of work 
practices that employees must have for controls to function 
effectively. For example, the user's manual for Stihl's gasoline-
powered hand-held portable saws recommends training of operators, and 
it indicates that operators need to know minimum water flow rates, how 
to control flow rate to ensure an adequate volume of water to the 
cutting area, and to rinse the screen if no or little water is fed to 
the cutting wheel during use (Document ID 3998, Attachment 12a, pp. 3, 
15, 23). Similarly, the effectiveness of local exhaust ventilation 
systems, another common method used to control exposures to respirable 
crystalline silica, is often enhanced by the use of proper work 
practices. For instance, when tuckpointing, employees should ensure 
that the shroud surrounding the grinding wheel remains flush against 
the working surface, when possible, to minimize the amount of dust that 
escapes from the collection system. Operating the grinder in one 
direction (counter to the direction of blade rotation) is effective in 
directing mortar debris into the exhaust system, and backing the blade 
off before removing it from the slot permits the exhaust system to 
clear accumulated dust (78 FR at 56474). Employees using vacuum 
controls also need to be aware of appropriate ways to clean the filter, 
such as using a valve on the vacuum to clean the filter with 
backpressure instead of pounding the filter on a surface (Document ID 
3998, Attachment 13b, p. 460).
    The record also contains evidence demonstrating the importance of 
employees understanding how to effectively operate and maintain 
controls on heavy equipment to prevent exposures to respirable 
crystalline silica in the construction industry. For example, IUOE 
noted that the role of operating engineers in ensuring integrity of 
enclosed cabs includes keeping windows and doors closed, maintaining 
good housekeeping practices, cleaning dust from boots before entering 
the cab, and reporting malfunctioning seals and air conditioning 
(Document ID 2262, pp. 35-36). In addition, IUOE noted that operator 
control of water flow rates for dust suppression is important for 
protecting employees from exposure and preventing excessive water 
runoff into the environment (Document ID 4234, Part 1, pp. 27-28). 
Anthony Bodway, Special Projects Manager at Payne & Dolan, Inc., 
representing the National Asphalt Pavement Association (NAPA), noted 
that all Payne & Dolan's operators have been trained to conduct daily 
maintenance checks of their equipment (Document ID 3583, Tr. 2194-
2195). A best practices bulletin developed in part by NAPA requires 
machine operators to demonstrate knowledge of the machine's dust 
suppression system including flow rates, maintenance, troubleshooting, 
and visual inspections; in addition a letter from manufacturer Wirtgen 
America stressed the importance of operator training on operating and 
maintaining machines to minimize respirable dust (Document ID 2181, pp. 
25, 52).
    OSHA agrees that actions, such as controlling water flow rates, 
ensuring integrity of controls, addressing a non-functioning control, 
and proper housekeeping in cabs, are work practices that promote 
effectiveness of controls. However, the Agency does not agree that 
construction employees who perform tasks that generate respirable 
crystalline silica dust require training beyond what paragraph 
(i)(2)(i)(C) of the standard for construction already requires. As 
noted above, paragraph (i)(2)(i)(C) of the standard for construction 
requires employers to ensure that employees covered by the standard can 
demonstrate knowledge and understanding of specific measures the 
employer has implemented to protect them from respirable crystalline 
silica exposure, including engineering controls, work practices, and 
respirators to be used. Under this provision, the knowledge required of 
each employee depends on the tasks he or she performs. That was the 
intent of the proposed standard and it has not changed in the standard. 
OSHA concludes that this provision, as written, requires employers to 
provide employees with the different types and levels of training they 
need, depending on the types of tasks they conduct. For example, 
laborers who do not operate equipment that generates respirable 
crystalline silica dust would only need to be aware of the general 
types of controls used, such as water and local exhaust. However, those 
laborers would need to know about work practices for tasks they 
perform, such as appropriate clean-up of respirable crystalline silica 
dust accumulations. On the other hand, employees who operate tools with 
built-in controls, such as saws with integrated water delivery systems, 
would need to demonstrate knowledge and understanding of the full and 
proper implementation of the controls on those tools.
    OSHA is also not mandating additional training for a competent 
person in paragraph (i) of the standard for construction. As discussed 
in more detail in the summary and explanation of Written Exposure 
Control Plan, the training requirements mandated by this standard 
already impart a high level of competence. OSHA recognizes that there 
may be situations in which an employee needs additional training in 
order to ensure that he or she has the knowledge, skill, and ability to 
be a designated competent person, but because of unique scenarios in 
construction environments, those training requirements would vary 
widely. OSHA concludes, therefore, that it is the employer's 
responsibility to identify and provide any additional training that the 
competent person would need to implement the written exposure control 
plan.
    AFL-CIO and USW requested that the standard for general industry 
also mandate a tiered approach that includes a higher level of training 
for employees who perform silica dust-generating tasks and training of 
a competent person; both those groups and UAW noted the importance of 
workplace- or job-specific training on engineering controls and work 
practices (Document ID 2282, Attachment 3, p. 24; 4204, p. 99; 4214, p. 
14).

[[Page 16848]]

    OSHA concludes that employees are already required to demonstrate 
workplace- and job-specific knowledge and understanding of work 
practices associated with the tasks they conduct under paragraph 
(j)(3)(i)(C) of the standard for general industry and maritime. That 
was the intent of the proposed standard and it has not changed in the 
standard. Engineering controls in general industry commonly involve 
measures such as ventilation systems that protect several employees, 
and are often not subject to the direct control of the employee 
performing the task (see Chapter IV of the Final Economic Analysis and 
Final Regulatory Flexibility Analysis). In those cases, training would 
include a description of the specific types of engineering controls 
used at that facility, including signs that the controls may not be 
working effectively (e.g., visible dust emission). Training would also 
address any work practices needed for the controls to function 
effectively (e.g., not opening windows near local exhaust sources, 
positioning the local exhaust hood directly over the exposure source). 
If employees covered by the general industry and maritime standard 
operate equipment with built in controls that are under their control, 
those employees are required to demonstrate knowledge and understanding 
of the full and proper implementation of those controls. Therefore, 
OSHA is not requiring additional training for general industry and 
maritime employees who perform tasks that generate respirable 
crystalline silica dust because it is already required by paragraph 
(j)(3)(i)(C) of the standard for general industry and maritime.
    Training of a competent person is not applicable to the general 
industry and maritime standard because OSHA is not requiring a 
competent person. As explained in the summary and explanation of 
Written Exposure Control Plan, OSHA is not requiring a competent person 
because reasons for designating a competent person in construction are 
not applicable to most general industry worksites. For example, general 
industry worksites usually have less environmental variability and it 
is reasonable and generally feasible to establish regulated areas to 
limit access and perform exposure assessments to verify effective 
control of exposure.
    OSHA has retained the proposed requirement for training on the 
contents of the respirable crystalline silica rule in paragraph 
(j)(3)(i)(D) of the standard for general industry and maritime 
(paragraph (i)(2)(i)(D) of the standard for construction). This 
paragraph parallels the HCS requirement to inform employees about the 
requirements of the HCS section (29 CFR 1910.1200(h)(2)(i)), and 
similar paragraphs have been included in all OSHA substance-specific 
standards.
    Proposed paragraph (i)(2)(i)(D) required employers to train 
employees about the purpose and description of the medical surveillance 
program, and OSHA has retained that requirement in the rule under 
paragraph (j)(3)(i)(E) of the standard for general industry and 
maritime (paragraph (i)(2)(i)(F) of the standard for construction). 
Paragraph (i) of the standard for general industry and maritime 
(paragraph (h) of the standard for construction) describes the 
requirements of the medical surveillance program, such as the 
examinations that must be offered to qualifying employees. OSHA finds 
that employees will benefit from learning about the purpose of medical 
surveillance and symptoms associated with respirable crystalline 
silica-related diseases, as described in the summary and explanation of 
Medical Surveillance. OSHA recommends that employers in construction or 
other high-turnover industries inform employees to keep their copy of 
the physician or other licensed health care professional's written 
medical opinion for the employer as proof of a current medical 
examination and that proof of a current examination could ensure that 
employees get timely examinations or spare employees from unnecessary 
testing, such as X-rays. OSHA also recommends that employers inform 
employees that they cannot be retaliated against for participating in 
medical surveillance. This information will help to ensure that 
employees are able to effectively participate in medical surveillance.
    The proposed rule did not require employees to be trained on the 
identity of the competent person. Several labor unions, including IUOE, 
LHSFNA, BAC, and BCTD requested that employees receive training on the 
written exposure control plan or identity of the competent person 
(Document ID 3583, Tr. 2367-2368; 3589, Tr. 4222; 2329, p. 5; 4223, p. 
118). Paragraph (g)(4) of the standard for construction requires 
employers to designate a competent person to make frequent and regular 
inspections of job sites, materials, and equipment to implement the 
written exposure control plan. The written exposure control plan in the 
construction standard describes tasks in the workplace that involve 
exposure to respirable crystalline silica; engineering controls, work 
practices, and respiratory protection used to limit employee exposures; 
housekeeping methods used to limit employee exposures; and procedures 
used to restrict access, when necessary, to minimize employees exposed 
and their level of exposure, including exposures generated by other 
employers or sole proprietors (paragraph (g)(1)(i)-(iv)). OSHA is not 
requiring the identity of the competent person to be listed in the 
written exposure control plan because it could change daily. However, 
construction employees must be able to identify the competent person in 
situations where they have a question or concern about the subjects 
covered in the written exposure control plan. For example, if an 
engineering control is not working properly, an employee may need to 
contact the competent person for help in addressing the problem. 
Therefore, paragraph (i)(2)(i)(E) of the standard for construction 
requires employees to be informed of the competent person's identity. 
However, OSHA is not specifying training on the written exposure 
control plan because the contents of that plan, including its 
availability to employees, is already addressed by training on the 
contents of this section under paragraph (i)(2)(i)(D) of the standard 
for construction.
    Some stakeholders requested that OSHA provide greater specificity 
on training requirements. For example, Fann Contracting, Inc. asked 
OSHA to spell out what training is required for different industries 
(Document ID 2116, Attachment 1, p. 46). NAHB stated that specifying 
training requirements would simplify training for construction 
employers (Document ID 2296, p. 44). John Scardella, Program 
Administrator for USW, testified that training should not be left to 
the discretion of employers because they might not prioritize employee 
health and safety (Document ID 3479, p. 2). USW and LHSFNA requested 
more detailed training requirements, such as those of the asbestos 
standard (29 CFR 1910.1001; 1926.1101) that specify what is to be 
addressed under each major training topic (Document ID 2336, pp. 14-15; 
3589, Tr. 4219).
    Although OSHA agrees with these commenters that comprehensive 
training is a key part of hazard communication, the Agency recognizes 
that it is difficult to provide more specificity as a result of unique 
scenarios among different employers and industries. However, to help 
employers develop training programs that are comprehensive for general 
training subjects that apply to most covered industries, OSHA has 
developed a number of guidance products that are already available

[[Page 16849]]

through its Web site. In addition, the Agency is planning to develop 
guidance products specific to the rule, as has been suggested by NAHB 
(Document ID 2296, p. 39). Numerous governmental and other 
organizations have already developed guidance products for training 
(e.g., Document ID 1722; 4025, Attachment 2; 4053, Exhibit 3a-3e and 4; 
4073, Attachment 8i). As has been the case with all OSHA standards, 
OSHA expects that the private sector will develop training products and 
programs, which will further help ensure comprehensive training.
    Commenters also argued that OSHA should include requirements for 
training on other topics. For example, IUOE requested training on 
topics such as SDSs, signs, use and care of respiratory protection, and 
work practices for heavy machine operators (Document ID 2262, pp. 36-
38; 4025, Attachment 1, p. 2). LHSFNA and BCTD requested training on 
exposure assessment (Document ID 3589, Tr. 4222; 4223, p. 118). AFSCME 
requested training on personal hygiene (Document ID 4203, p. 7).
    OSHA concludes, however, that the employee information and training 
provisions in the respirable crystalline silica rule and the HCS are 
sufficiently informative. For example, the HCS requires employers to 
provide training on SDSs and on the signal words and hazard statements 
that are used on the signs required by the general industry and 
maritime standard. Under the HCS, employers must also train employees 
about the location and availability of the written HCS program, 
including the required list(s) of hazardous chemicals and SDSs. The HCS 
also requires employers to train employees on the methods and 
observations that may be used to detect the presence or release of a 
hazardous chemical in the work area; in the case of respirable 
crystalline silica, this could include a description of the employer's 
exposure assessments methods (e.g., objective assessments, personal 
breathing zone air sampling, direct readings of respirable dust) and 
warnings that visible dust emissions might indicate a problem.
    Because employers must meet the requirements of the HCS, OSHA does 
not find it necessary to repeat the training requirements of that 
standard in their entirety in the respirable crystalline silica rule. 
Moreover, even if all training requirements of the HCS were repeated in 
the respirable crystalline silica rule, most employers would still have 
to consult the hazard communication requirements of other hazardous 
chemicals, because they have employees exposed to other chemicals in 
their workplace. Consequently, OSHA concludes that these provisions, 
and the other requirements of the HCS and this standard, are 
sufficient.
    OSHA also concludes that additional training on respiratory 
protection or personal hygiene is unnecessary. Training on the use and 
care of respiratory protection is already required under the 
respiratory protection standard (29 CFR 1910.134). OSHA similarly 
concludes that training in personal hygiene is not needed as a required 
training topic in this rule because personal hygiene measures relevant 
to respirable crystalline silica exposure, such as avoiding use of 
compressed air as a method to clean dust off of clothing, are 
adequately addressed by other requirements of the rule and are covered 
by training on work practices. Some training topics suggested by 
commenters, such as communication methods for employees in enclosed 
cabs, are specific to certain work scenarios. OSHA has concluded that 
employers are in the best position to determine which additional, 
unique training requirements are relevant to their type of industry. 
For example, in construction, the competent person might be able to 
identify situations where employees need more training because they are 
not demonstrating knowledge and understanding of a specific measure the 
employee has implemented to protect them.
    OSHA's proposed rule required the employer to make a copy of the 
standard readily available without cost to each employee covered by the 
respirable crystalline silica rule, and OSHA has retained this 
requirement in paragraph (j)(3)(ii) of the standard for general 
industry and maritime (paragraph (i)(2)(ii) of the standard for 
construction). This is a common requirement in OSHA standards such as 
chromium (VI) (29 CFR 1910.1026), acrylonitrile (29 CFR 1910.1045), and 
cotton dust (29 CFR 1910.1043). The provision leaves employers free to 
determine the best way to make the standard available, such as a 
printed or electronic copy in a central location that employees can 
easily access. OSHA concludes that employees need to be familiar with 
and have access to the respirable crystalline silica standard for 
general industry and maritime or construction, as applicable, and be 
aware of the employer's obligations to comply with it.
    OSHA did not propose a requirement for labels or signs in languages 
other than English. Ameren requested the rule include a requirement 
that labels include appropriate languages for employees who do not 
understand English (Document ID 2315, p. 4). Charles Gordon and BAC 
requested that warning signs be presented in a language or manner that 
employees can understand, and, as noted by BAC, the method could 
include graphics (Document ID 3588, Tr. 3805; 4219, p. 27). 
Requirements for labels on hazardous chemicals are set forth in 
paragraph (f) of the HCS, which does not require languages other than 
English. However, the HCS requires the inclusion of certain information 
on labels on shipped containers, including pictograms (29 CFR 
1910.1200(f)(1)(iv)), and mandates that containers in the workplace be 
labeled either in accordance with the rules for shipping containers or 
with product identifier and combinations of words, pictures, or symbols 
to warn of hazards. OSHA has concluded that with training required 
under the HCS (29 CFR 1910.1200(h)(3)(iv)), even employees who are not 
literate in English will have sufficient knowledge of respirable 
crystalline silica hazards. Likewise, with training, employees will be 
able to recognize the meaning of signs at the entrances to regulated 
areas and the need for respiratory protection in these areas.
    OSHA's proposed rule did not specify when and how often employees 
must be trained. Some stakeholders offered opinions about when an 
employer's obligation to train covered employees should begin. For 
example, USW, NCOSH, and LHSFNA requested that the rule for respirable 
crystalline silica require training before or at the time employees are 
assigned or placed in a job with respirable crystalline silica exposure 
(Document ID 3479, p.1; 3955, Attachment 2, p. 1; 3589, Tr. 4222). CWA, 
Upstate Medical College, UAW, AFSCME, AFL-CIO, and BCTD requested that 
the rule for respirable crystalline silica require training before 
employees are assigned to or placed in a job or task with respirable 
crystalline silica exposure (Document ID 2240, p. 4; 2244, p. 4; 2282, 
Attachment 3, pp. 24-25; 4203 p. 7; 4204, p. 99; 4223, p. 117).
    OSHA agrees that each employee needs to be trained sufficiently to 
understand the specified training elements at the time of initial 
assignment to a position involving exposure to respirable crystalline 
silica. The rule requires the employer to ensure that each employee can 
demonstrate knowledge and understanding of the specified training 
elements; this requirement applies from the time that the employee is 
covered by the rule. This requirement is consistent with the HCS, which 
requires that employers provide employees with

[[Page 16850]]

effective information and training on hazardous chemicals in their work 
area at the time of their initial assignment (29 CFR 1910.1200(h)(1)).
    Stakeholders also commented on how often employers should be 
required to train their employees. CWA, Upstate Medical College, UAW, 
NCOSH, AFSCME, and LHSFNA recommended periodic refresher training and 
additional training if methods, equipment, or controls change (Document 
ID 2240, p. 4; 2244, p. 4; 2282, Attachment 3, pp. 24-25; 3955, 
Attachment 2, p. 2; 4203 p. 8; 3589, Tr. 4222). Similarly, USW and AFL-
CIO asked that OSHA require periodic refresher training (Document ID 
3479, p.1; 4204, p. 99). In addition, BCTD recommended additional 
training when the employer believes an employee requires more training 
because of a lack of skill or understanding (Document ID 4223, p. 117).
    OSHA agrees with commenters that additional or repeated training 
may be necessary under certain circumstances but does not consider it 
appropriate to impose a fixed schedule of periodic training. Therefore, 
the requirement for training is performance-oriented in order to allow 
flexibility for employers to provide training as needed to ensure that 
each employee can demonstrate the knowledge and understanding required 
under the rule. For example, if an employer observes an employee 
engaging in activities that contradict knowledge gained through 
training, it is a sign to the employer that the employee may require a 
reminder or periodic retraining on work practices.
    Because paragraph (j)(3)(i)(C) of the standard for general industry 
and maritime (paragraph (i)(2)(i)(C) of the standard for construction) 
requires training on the specific measures the employee has implemented 
to protect employees, additional training is already required after new 
engineering controls are installed, new work practices are implemented, 
or employees are given new types of respirators. Because this provision 
requires employers to provide additional training following changes in 
protective measures or equipment, they ensure that employees are able 
to properly use the new controls, implement work practices relating to 
those controls, and properly use respirators to actively protect 
themselves under the conditions found in the workplace, even if those 
conditions change.
    OSHA did not include a requirement for employees to be certified as 
having received training in the proposed rule. Commenters including Dr. 
Ruth Ruttenberg, representing the AFL-CIO, have voiced support for a 
portable training record or certification-based approach; Dr. 
Ruttenberg noted that this would reduce costs by avoiding the need for 
each new employer to conduct full training (Document ID 1950, pp. 11-
12; 2256, Attachment 4, p. 5; 4235, p. 14). OSHA is not including a 
requirement for a portable training record in the rule. This approach 
is consistent with the HCS, which neither requires nor precludes a 
training record that could be portable. Employee training requirements 
might be partially fulfilled by training obtained through trade 
associations, unions, colleges, or professional schools. However, the 
employer is always ultimately responsible for ensuring that employees 
are adequately trained, regardless of the method relied upon to comply 
with the training requirements.
    OSHA concludes that a portable training record is unlikely to 
eliminate the need for employer-specific or site-specific training. For 
example, Barbara McCabe, Program Manager for IUOE, testified that IUOE 
local unions train employees but employees would need site-specific 
training when they report to the worksite (Document ID 3583, Tr. 2368). 
An example of a case where site-specific training is needed was noted 
by BAC, who commented that an employee who operated a saw with water 
controls at one site may be given a saw with vacuum controls at another 
site (Document ID 4219, p. 23).
    OSHA concludes that some site-specific or employer-specific 
training is always necessary, such as training on specific tasks that 
could result in exposures, controls or work practices that the employer 
has implemented, or the identity of the competent person (paragraphs 
(j)(3)(i)(B) and (C) of the standard for general industry and maritime 
and paragraphs (i)(2)(i)(B), (C), and (E) of the standard for 
construction). Full training would not be required if an employee is 
already able to demonstrate knowledge in health hazards, the contents 
of the respirable crystalline silica rule, or medical surveillance for 
respirable crystalline silica (paragraphs (j)(3)(i)(A), (D), and (E) of 
the standard for general industry and maritime, paragraphs 
(i)(2)(i)(A), (D) and (F) of the standard for construction). Site-
specific training is unlikely to be costly or time-consuming. OSHA 
concludes that assessing an employee's knowledge to determine the type 
and level of additional training required is more meaningful than 
simply accepting a certificate of training.
    Bill Kojola requested that the rule specify that training be 
provided at no cost to the employee and during work hours (Document ID 
3955, Attachment 2, p. 2). In addition, Norlan Trejo from New Labor 
testified that he never saw an employer pay for training (Document ID 
3583, Tr. 2469). As stated above, an employer may rely on an employee's 
previous training, if the employee can demonstrate knowledge in 
training requisites. Any training provided by the employer to meet the 
requirements of the rule must be provided at no cost to the employee. 
Employees must also be paid for time spent in training. This is 
consistent with other OSHA standards that do not include an explicit 
requirement for employer payment for training in the regulatory text, 
e.g., the HCS requires training (1910.1200(h)(3)) but does not mention 
cost; the compliance directive (CPL 02-02-079 says ``Training is 
required to be provided at no cost to the employees. Employees must be 
paid for the time they spend at training.)''
    In the Notice of Proposed Rulemaking, OSHA asked whether labeling 
of substances containing more than 0.1 percent crystalline silica was 
appropriate, as required by the HCS, or if the threshold for labeling 
should be greater than 1 percent crystalline silica (78 FR at 56291). A 
number of industry groups suggested a threshold for including 
respirable crystalline silica on labels or SDSs. With the exception of 
NISA, who favored a 0.1 percent threshold, the commenters requested a 
threshold of 1 percent or greater or thought that a 0.1 percent 
threshold could be problematic (Document ID 1785, p. 4; 2179, pp. 3-4; 
2101, pp. 8-9; 2284, p. 10; 2296, p. 44; 2312, p. 3; 2317, p. 3; 2319, 
p. 120; 2327, Attachment 1, p. 14; 4208, pp. 19-20). The International 
Diatomite Producers Association agreed with NISA that the threshold for 
hazard communication should be 0.1 percent for respirable crystalline 
silica but requested an exception for respirable crystalline silica in 
natural (uncalcined) diatomaceous earth, according to OSHA's current 
policy (Document ID 4212, pp. 6-7).
    The classification of hazardous chemicals, including chemicals 
containing silica, is determined by the HCS. As explained in Section V, 
Health Effects, OSHA has determined, consistent with the National 
Toxicology Program and International Agency for Research on Cancer 
classifications, that respirable crystalline silica is a carcinogen. 
Under the HCS, a mixture that contains a carcinogen must itself be 
classified as a carcinogen when at least one ingredient in it has been 
classified as a Category 1 or Category 2 carcinogen

[[Page 16851]]

and is present at or above the appropriate cut-off value/concentration 
limit specified in HCS Table A.6.1 (29 CFR 1910.1200, Appendix A, 
A.6.3.1). Table A.6.1 sets the cut-off value at greater than or equal 
to 0.1 percent. Footnote 7 to 1910.1200, Appendix A, A.6.3 notes that 
the cut-off value is the primary means of classification of carcinogens 
and may only be modified on a case-by-case evaluation based on 
available test data for the mixture as a whole. Classification of a 
chemical under the HCS triggers labeling requirements under that 
standard, and OSHA does not find it appropriate to impose different 
requirements in this rule. To do so would be at odds with the concept 
of harmonizing national and international requirements for 
classification and labelling of chemicals that is the basis of the GHS 
and HCS.
    OSHA also did not propose requirements related to the creation and 
retention of training records, but some commenters expressed opinions 
on this issue. For example, CISC commented that they would agree to 
document that employees completed training and demonstrated knowledge 
(Document ID 4217, p. 25). Consistent with the HCS, employers are not 
required to keep records of training under the rule for respirable 
crystalline silica, but employers may find it valuable to do so. 
Comments on this issue and OSHA's rationale for this decision are 
discussed in the summary and explanation of Recordkeeping.
    ASTM standards. The training requirements in the respirable 
crystalline silica standards are generally consistent with but differ 
slightly from ASTM International (ASTM) standards ASTM E 1132-06, 
Standard Practice for Health Requirements Relating to Occupational 
Exposure to Respirable Crystalline Silica and ASTM E 2625-09, Standard 
Practice for Controlling Occupational Exposure to Respirable 
Crystalline Silica for Construction and Demolition Activities (Section 
4.8 in both E 1132-06 and E 2625-09) (Document ID 1466, p. 6; 1504, p. 
6). The E 1132-06 standard requires training for employees exposed at 
any level and the E 2625-09 standard for construction and demolition 
requires training for employees potentially exposed to high levels. The 
ASTM standards also include: (1) More specificity on training 
requirements such as annual training (E 1132-06 only), training when 
employees demonstrate unsafe work practices, training in an appropriate 
language and manner, and documentation of training (certification in 
the case of E 1132-06); (2) training on tuberculosis and relationships 
between smoking and silica exposure in both standards and no training 
for autoimmune and kidney hazards in E 2625-09; (3) training on 
respirator use and hygiene; and (4) warning signs for construction and 
demolition workplaces in E 2625-09.
    OSHA is requiring that each employee covered by the rule receive 
training; employees may be at significant risk even if they are not 
exposed to ``high levels'' of respirable crystalline silica. In 
comparison to the ASTM standards, the requirements for training under 
the respirable crystalline silica rule are more performance-based in 
terms of when training is required. The health hazards addressed in the 
rule are based upon OSHA's health effects assessments and consistency 
with health hazard classification in the HCS. OSHA already requires 
training on respirator use under its respiratory protection standard 
(29 CFR 1910.134). The rule does not specify training on hygiene 
because personal hygiene is addressed by other requirements of the rule 
and training on work practices. OSHA is not requiring warning signs in 
the standard for construction because employers are in the best 
position to determine if and when signs are appropriate for restricting 
access to work areas to limit employee exposure to respirable 
crystalline silica. For the reasons described above, OSHA concludes 
that the requirements of the rule better effectuate the purposes of the 
OSH Act of 1970 than the ASTM standards.

Recordkeeping

    Paragraph (k) of the standard for general industry and maritime 
(paragraph (j) of the standard for construction) requires employers to 
make and maintain air monitoring data, objective data, and medical 
surveillance records. The recordkeeping requirements are in accordance 
with section 8(c) of the Occupational Safety and Health (OSH) Act (29 
U.S.C. 657(c)), which authorizes OSHA to require employers to keep and 
make available records as necessary or appropriate for the enforcement 
of the OSH Act or for developing information regarding the causes and 
prevention of occupational accidents and illnesses.
    Paragraph (k)(1)(i) of the standard for general industry and 
maritime (paragraph (j)(1)(i) of the standard for construction) is 
substantively unchanged from the proposed rule. It requires the 
employer to make and maintain accurate records of all exposure 
measurements taken to assess employee exposure to respirable 
crystalline silica, as prescribed in paragraph (d) of the standard for 
general industry and maritime (paragraph (d)(2) of the standard for 
construction). OSHA has added the words ``make and'' prior to 
``maintain'' in order to clarify that the employer's obligation is to 
create and preserve such records. This clarification has also been made 
for other records required by the silica rule. In addition, OSHA now 
refers to ``measurements taken to assess employee exposure'' rather 
than ``measurement results used or relied on to characterize employee 
exposure.'' This change is editorial, and is intended to clarify OSHA's 
intent that all measurements of employee exposure to respirable 
crystalline silica be maintained. Paragraph (k)(1)(ii) of the standard 
for general industry and maritime (paragraph (j)(1)(ii) of the standard 
for construction) requires that such records include the following 
information: The date of measurement for each sample taken; the task 
monitored; sampling and analytical methods used; the number, duration, 
and results of samples taken; the identity of the laboratory that 
performed the analysis; the type of personal protective equipment, such 
as respirators, worn by the employees monitored; and the name, social 
security number, and job classification of all employees represented by 
the monitoring, indicating which employees were actually monitored.
    OSHA has made one editorial modification that differs from the 
proposed rule in paragraph (k)(1)(ii)(B) of the standard for general 
industry and maritime (paragraph (j)(1)(ii)(B) of the standard for 
construction) and that is to change ``the operation monitored'' to 
``the task monitored.'' Both ``task'' and ``operation'' are commonly 
used in describing work. However, OSHA uses the term ``task'' 
throughout the rule, and the Agency is using ``task'' in the 
recordkeeping provision for consistency and to avoid any potential 
misunderstanding that could result from using a different term. This 
editorial change neither increases nor decreases an employer's 
obligations as set forth in the proposed rule.
    The recordkeeping provision that received the most comments was 
proposed paragraph (j)(1)(ii)(G) (now paragraph (k)(1)(ii)(G) of the 
standard for general industry and maritime, paragraph (j)(1)(ii)(G) of 
the standard for construction), which, consistent with existing 
recordkeeping requirements in OSHA health standards, requires the 
employer to include in the standard's mandated records the employee's 
social security number. Morgan Electro Ceramics, National Electrical 
Carbon Products, Inc. (NECP), Southern Company, the National Tile 
Contractors

[[Page 16852]]

Association (NTCA), Dow Chemical Company, the Asphalt Roofing 
Manufacturers Association (ARMA), the American Petroleum Institute 
(API), the Marcellus Shale Coalition, Ameren Corporation, the North 
American Insulation Manufacturers Association (NAIMA), Edison Electric 
Institute (EEI), the Tile Council of North America (TCNA), the American 
Foundry Society (AFS), the Nevada Mining Association (NMA), Newmont 
Mining Corporation (NM), and others opposed the requirement (e.g., 
Document ID 1772, p.1; 1785, pp. 9-10; 2185, pp. 8; 2267, p. 7; 2270, 
p. 3; 2291, p. 26; 2301, Attachment 1, pp. 80-81; 2311, p. 3; 2315, p. 
7; 2348, Attachment 1, p. 39; 2357, pp. 36-37; 2363, p. 7; 2379, 
Appendix 1, p. 73; 2107, p. 4; 1963, p. 3). The commenters, citing 
employee privacy and identity theft concerns, wanted to be allowed to 
use an identifier other than the social security number, such as an 
employee identification number, an employee driver's license number, or 
another unique personal identification number. For example, NAIMA 
stated ``Using social security numbers is a dangerous threat to 
personal privacy and identify theft that OSHA should affirmatively 
discourage'' (Document ID 2348, Attachment 1, p. 39). Commenters 
acknowledged that social security numbers must be used for some reports 
to the government and thus are present in some employer records, but 
that access to these records is usually more restricted than to air 
monitoring records.
    OSHA has considered the comments it received on this issue and has 
decided to retain the requirement for including the employee's social 
security number in the recordkeeping requirements of the rule. The 
requirement to use an employee's social security number is a long-
standing OSHA practice, based on the fact that it is a number that is 
both unique to an individual and is retained for a lifetime, and does 
not change as an employee changes employers. The social security number 
is therefore a useful tool for tracking employee exposures, 
particularly where exposures are associated with diseases such as 
silicosis that generally have a long latency period and can develop 
over a period of time during which an employee may have several 
employers.
    OSHA is cognizant of the privacy concerns expressed by commenters 
regarding this requirement, and understands the need to balance that 
interest against the public health interest in requiring the social 
security identifier. Instances of identity theft and breeches of 
personal privacy are widely reported and concerning. However, OSHA has 
concluded that this rule should adhere to the past, consistent practice 
of requiring employee social security numbers on exposure records 
mandated by every OSHA substance-specific health standard, and that any 
change to the Agency's requirements for including employee social 
security numbers on exposure records should be comprehensive. Some 
employers who are covered by this rule, such as employers who perform 
abrasive blasting on surfaces coated with lead, cadmium, or chromium 
(VI), will be covered by more than one OSHA standard. OSHA examined 
alternative forms of identification in Phase II of the Agency's 
Standards Improvement Project, but did not revise requirements for the 
use of social security numbers (70 FR 1111-1144 (1/5/2005)). 
Nevertheless, given increasing concerns regarding identity theft and 
privacy issues, as evidenced by stakeholder comments in this rulemaking 
record, OSHA intends to examine the requirements for social security 
numbers in all of its substance-specific health standards in a future 
rulemaking. In the meantime, the requirement to use and retain social 
security numbers to comply with this rule remains.
    The remaining requirements of paragraph (k)(1)(ii) of the standard 
for general industry and maritime (paragraph (j)(1)(ii) of the standard 
for construction) are generally consistent with those found in other 
OSHA standards, such as the standards for methylene chloride (29 CFR 
1910.1052) and chromium (VI) (29 CFR 1910.1026). The additional 
requirement to include the identity of the laboratory that performed 
the analysis of exposure measurements is for the reason stated in the 
preamble to the Notice of Proposed Rulemaking (NPRM), which is that 
analysis of crystalline silica samples must conform with the 
requirements listed in the rule (i.e., in Appendix A), and that can 
only be determined by knowing the identity of the laboratory that 
performed the analysis.
    Fann Contracting, Inc. commented that OSHA's proposed rule would 
create a ``recordkeeping nightmare'' and raised concerns about the 
difficulties of managing air monitoring data for over 200 employees 
scattered around the state, with 7 to 8 ongoing projects and 12 to 15 
total projects per year (Document ID 2116, Attachment 1, p. 11). The 
American Subcontractors Association expressed concerns about the high 
costs of transferring data to new technology or keeping records in 
paper format (Document ID 2187, p. 7).
    OSHA understands that, as with any recordkeeping requirement in a 
comparable rule, there will be time, effort, and expense involved in 
developing and maintaining records. However, OSHA expects that even 
employers who manage multiple projects will have a system for 
maintaining these records, just as they do for their other business 
records. As for high expenses of transferring data to new technology, 
the Agency understands that there are multiple ways to maintain these 
records and there are expenses involved in doing so. Therefore, the 
Agency is allowing employers the option to use whatever method works 
best for them, paper or electronic.
    Paragraph (k)(1)(iii) of the standard for general industry and 
maritime (paragraph (j)(1)(iii) of the standard for construction) is 
unchanged from the proposed rule. It requires the employer to ensure 
that exposure records are maintained and made available in accordance 
with OSHA's access to employee exposure and medical records standard, 
which specifies that exposure records must be maintained for 30 years 
(29 CFR 1910.1020(d)(i)(ii)). Commenters addressed the issue of how 
long an employer should maintain exposure records. The National 
Industrial Sand Association (NISA) noted that its occupational health 
program requires NISA members to retain employee air monitoring records 
indefinitely (Document ID 2195, p. 35). NISA supported the proposed 
requirement that air monitoring records be retained for 30 years 
(Document ID 2195, p. 46). Other commenters advocated recordkeeping 
durations ranging from 10 years to 40 years (e.g., Document ID 2210, 
Attachment 1, p. 8; 2319, p. 122; 2339, p. 10; 4025, pp. 8-9). The 
American Society of Safety Engineers (ASSE) recommended that air 
monitoring records should be retained for 40 years or the duration of 
employment plus 20 years, whichever is longer, due to latency periods 
of some silica-related illnesses (Document ID 2339, p. 10). The 
International Union of Operating Engineers indicated that 10 years is 
more than adequate time to retain air monitoring data; it commented 
that British Columbia, Canada requires retention for 10 years (Document 
ID 4025, pp. 8-9). The Construction Industry Safety Coalition and the 
National Federation of Independent Business (NFIB) expressed the view 
that 30 years is too long, but did not make recommendations for what 
they considered a suitable duration (Document ID 2319, pp. 121-122; 
2210, Attachment 1, p. 8). NFIB alleged that employers will have to 
maintain and

[[Page 16853]]

make available records of all activities relating to each requirement 
of the rule if the company wants to ensure it can show a good-faith 
effort to comply, and indicated that keeping records for 30 years would 
lead to a ``staggering'' amount of paperwork (Document ID 2210, 
Attachment 1, p. 8).
    After reviewing the comments in this record, OSHA has concluded 
that the best approach is to maintain consistency with 29 CFR 1910.1020 
and its required time period for retention of exposure records of 30 
years. OSHA explained in that rulemaking that it is necessary to keep 
exposure records for this extended time period because of the long 
latency period between exposure and development of silica-related 
disease (45 FR 35212, 35268-35271 (5/23/80)). For example, silicosis is 
often not detected until 20 years or more after initial exposure. The 
extended record retention period is therefore needed because 
establishing causality of disease in employees is assisted by, and in 
some cases can only be made by, having present and past exposure data 
(as well as any objective data relied on by the employer and present 
and past medical surveillance records, as discussed below).
    In retaining the 30-year retention period, OSHA does not agree with 
commenters who recommended extending it to at least 40 years, or even 
indefinitely. The Agency concludes that the 30-year retention period 
specified in 29 CFR 1910.1020 represents a reasonable balance between 
the need to maintain exposure records and the administrative burdens 
associated with maintaining those records for extended time periods. 
Because the 30-year records-retention requirement is included in 29 CFR 
1910.1020, this duration is consistent with longstanding Agency and 
employer practice. Other substance-specific rules are also subject to 
the retention requirements of 29 CFR 1910.1020, such as the standards 
addressing exposure to methylene chloride (29 CFR 1910.1052) and 
chromium (VI) (29 CFR 1910.1026). The Agency also disagrees that the 
30-year retention requirement will lead to a ``staggering'' amount of 
paperwork, as NFIB commented (Document ID 2210, Attachment 1, p. 8). 
Electronic recordkeeping has become commonplace. Commenters such as the 
Association of Energy Service Companies and ASSE support the use of 
electronic or digital records to ease paperwork burdens (Document ID 
2344, p. 2; 2339, p. 5). Thus, OSHA finds that the 30-year retention 
period is necessary and appropriate for air monitoring data.
    Paragraph (k)(2)(i) of the standard for general industry and 
maritime (paragraph (j)(2)(i) of the standard for construction) is 
substantively unchanged from the proposed rule. It requires employers 
who rely on objective data to keep accurate records of the objective 
data. Paragraph (k)(2)(ii) of the standard for general industry and 
maritime (paragraph (j)(2)(ii) of the standard for construction) 
requires the record to include: The crystalline silica-containing 
material in question; the source of the objective data; the testing 
protocol and results of testing; a description of the process, task, or 
activity on which the objective data were based; and other data 
relevant to the process, task, activity, material, or exposures on 
which the objective data were based. Paragraphs (k)(2)(ii)(D) and (E) 
of the standard for general industry and maritime (paragraphs 
(j)(2)(ii)(D) and (E) of the standard for construction) have been 
modified from the proposed rule to substitute the word ``task'' for 
``operation'' and to clarify the requirements for records of objective 
data. These changes are editorial, and do not affect the employer's 
obligations as set forth in the proposed rule.
    Since the rule allows objective data to be used to exempt the 
employer from monitoring requirements and to provide a basis for 
selection of respirators, OSHA considers it critical that the use of 
objective data be documented. As authorized in the rule, reliance on 
objective data is intended to provide the same degree of assurance that 
employer monitoring of employee exposures by taking air samples does. 
The specified content elements are required to ensure that the records 
are capable of demonstrating to OSHA a reasonable basis for the 
conclusions drawn by the employer from the objective data.
    OSHA considers objective data to be employee exposure records that 
must be maintained. Paragraph (k)(2)(iii) of the standard for general 
industry and maritime (paragraph (j)(2)(iii) of the standard for 
construction) is unchanged from the proposed rule. It requires the 
employer to ensure that objective data are maintained and made 
available for 30 years in accordance with 29 CFR 1910.1020(d)(1)(ii)).
    The National Asphalt Pavement Association recommended that OSHA 
clarify that ``. . . for an operation provided the controls outlined in 
Table 1, no further records of objective data would be required'' 
(Document ID 2181, p. 13). OSHA confirms that an employer who fully and 
properly implements the control measures in Table 1 does not need to 
have objective data since no exposure assessment (including those based 
on objective data) is required when the employer is following Table 1. 
Therefore, following Table 1 does not trigger a recordkeeping or 
retention requirement.
    Associated Builders and Contractors, Inc. (ABC) and ASSE addressed 
the issue of retaining objective data records for 30 years (Document ID 
2289, p. 8; 2339, p. 10). ABC expressed concerns that data could be 
lost or destroyed during the 30-year period, and thought it would be 
difficult to enforce this provision. Furthermore, it commented that 
there is a ``. . . large and burdensome amount of records that an 
employer would need to store and maintain'' (Document ID 2289, p. 8). 
ABC did not make a recommendation on how long employers should maintain 
objective data records. ASSE commented that 30 years is too short and 
recommended that objective data records be retained for 40 years or the 
duration of the employment plus 20 years, whichever is longer, due to 
latency periods of some silica-related illnesses (Document ID 2339, p. 
10). For the same reasons noted in the explanation above for retaining 
air monitoring data pursuant to paragraph (k)(1)(iii) of the standard 
for general industry and maritime (paragraph (j)(1)(iii) of the 
standard for construction), OSHA finds that the 30-year retention 
period is necessary and appropriate for objective data.
    Paragraph (k)(3)(i) of the standard for general industry and 
maritime (paragraph (j)(3)(i) of the standard for construction) 
requires the employer to make and maintain an accurate record for each 
employee subject to medical surveillance under paragraph (i) of the 
standard for general industry and maritime (paragraph (h) of the 
standard for construction). Paragraph (k)(3)(ii) of the standard for 
general industry and maritime (paragraph (j)(3)(ii) of the standard for 
construction) lists the categories of information that an employer is 
required to record: The name and social security number of the 
employee; a copy of the PLHCPs' and specialists' written medical 
opinions for the employer; and a copy of the information provided to 
the PLHCPs and specialists where required by paragraph (i)(4) of the 
standard for general industry and maritime (paragraph (h)(4) of the 
standard for construction). The information provided to the PLHCPs and 
specialists includes the employee's duties as they relate to 
crystalline silica exposure, crystalline silica exposure levels, 
descriptions of personal protective equipment used by the employee, and 
information from employment-related medical

[[Page 16854]]

examinations previously provided to the employee (paragraph (i)(4) of 
the standard for general industry and maritime, paragraph (h)(4) of the 
standard for construction).
    In paragraph (k)(3)(ii)(B) of the standard for general industry and 
maritime (paragraph (j)(3)(ii)(B) of the standard for construction), 
OSHA has changed the ``PLHCP's and pulmonary specialist's written 
opinions'' to the ``PLHCPs' and specialists' written medical 
opinions.'' The change, consistent with paragraph (i) of the standard 
for general industry and maritime (paragraph (h) of the standard for 
construction), is made to reflect the revised definition for the term 
``specialist'' included in the rule.
    Paragraph (k)(3)(iii) of the standard for general industry and 
maritime (paragraph (j)(3)(iii) of the standard for construction) is 
unchanged from the proposed rule. It requires that medical records must 
be maintained for at least the duration of employment plus 30 years in 
accordance with 29 CFR 1910.1020(d)(1)(i), which governs application of 
the retention requirements in this rule. Pursuant to 29 CFR 
1910.1020(d)(1)(i)(C), medical records of employees who have worked for 
less than one year for the employer need not be retained beyond the 
term of employment if they are provided to the employee upon the 
termination of employment. This exception allows employers flexibility 
and the option not to retain medical records in these circumstances (53 
FR 38140, 38153-38155 (9/29/88)). This provision greatly reduces the 
recordkeeping burden on employers of short-term employees, including 
many construction employees covered by this rule. Of course, neither 
this rule nor 29 CFR 1910.1020 prohibits employers from keeping the 
medical records of employees who worked less than one year, and some 
employers may choose to keep the records. As indicated earlier, 
employers have the option to keep records in electronic or paper form.
    The employer is responsible for the maintenance of records in his 
or her possession (e.g., the PLHCP's written medical opinion for the 
employer described in paragraph (i)(6) of the standard for general 
industry and maritime (paragraph (h)(6) of the standard for 
construction)). The employer is also responsible for ensuring the 
retention of records in the possession of the PLHCP (e.g., the written 
medical report for the employee described in paragraph (i)(5) of the 
standard for general industry and maritime (paragraph (h)(5) of the 
standard for construction)) that are created pursuant to this rule's 
medical surveillance requirements. This responsibility, which derives 
from 29 CFR 1910.1020(b), means that employers must ensure that the 
PLHCP retains a copy of medical records for the employee's duration of 
employment plus 30 years. The employer can generally fulfill this 
obligation by including the retention requirement in the agreement 
between the employer and the PLHCP.
    Commenters objecting to the recordkeeping requirements for medical 
records were concerned with privacy and costs. OSCO Industries asserted 
that the medical recordkeeping provisions would be subject to the 
Health Insurance Portability and Accountability Act (HIPAA), and thus 
employers would be denied access to the records (Document ID 1992, p. 
12). The National Electrical Contractors Association (NECA) also 
expressed concerns about the application of HIPAA (Document ID 2295, p. 
2). NECA indicated that the recordkeeping requirements would ``. . . 
inundate most businesses with paperwork . . .'' and would be ``. . . an 
economic burden to employers in the construction industry . . .'' 
(Document ID 2295, p. 2). Fann Contracting and Leading Builders of 
America said that medical records would be very expensive and difficult 
to maintain (Document ID 2116, Attachment 1, p. 11; 2269, p. 19). Fann 
Contracting commented that they have multiple projects, as many as 7 to 
8 ongoing and 12 to 15 per year, with over 200 employees scattered 
around the state, which makes the new requirements ``a recordkeeping 
nightmare'' (Document ID 2116, Attachment 1, p. 11).
    As to the expense and difficulty of maintaining the medical 
records, OSHA recognizes that there will be time, effort, and expense 
involved in maintaining medical records. However, as stated earlier, 
OSHA expects that employers who manage multiple projects will have a 
system for maintaining these records, just as they do for their other 
business records. The adverse health effects associated with 
crystalline silica are very serious, and OSHA has concluded that the 
recordkeeping requirements are necessary to ensure that records are 
available to assist PLHCPs in identifying health conditions that may 
place employees at increased risk from exposure, as well as identifying 
and treating adverse health effects that may develop among employees. 
Therefore, OSHA concludes that the requirements for making and 
maintaining medical records are reasonable, and are essential for the 
health and safety of employees.
    As to the concerns expressed regarding the application of HIPAA, 
the requirement for retention of medical records in this standard (like 
those in other OSHA standards) is consistent with HIPAA. HIPAA allows 
for disclosure of certain health information to an employer where 
needed to comply with OSHA requirements for medical surveillance (45 
CFR 164.512). Moreover, this standard's requirement that medical 
surveillance reports be provided to workers rather than to employers 
eliminates much of this concern.
    Morgan Electro Ceramics, NECP, Southern Company, NTCA, Dow 
Chemical, ARMA, API, the Marcellus Shale Coalition, Ameren, NAIMA, EEI, 
TCNA, AFS, NMA, NM and others also questioned the requirement that the 
employee's social security number be included in medical records 
(Document ID 1772, p. 1; 1785, pp. 9-10; 2185, pp. 8; 2267, p. 7; 2270, 
p. 3; 2291, p. 26; 2301, Attachment 1, pp. 80-81; 2311, p. 3; 2315, p. 
7; 2348, Attachment 1, p. 39; 2357, pp. 36-37; 2363, p. 7; and 2379, 
Appendix 1, p. 73; 2107, p. 4; 1963, p. 3).
    As noted above in the discussion on air monitoring data, OSHA finds 
the privacy and security issues associated with the required use of 
social security numbers are of concern. However, for the same reasons 
discussed above with regard to employee exposure records, the Agency 
has decided to retain the requirement for use of social security 
numbers in medical records. As stated above, OSHA intends separately 
from this rulemaking to examine the requirements for social security 
numbers in all of its substance-specific health standards in order to 
address the issue comprehensively and ensure consistency among 
standards.
    In total, the recordkeeping requirements fulfill the purposes of 
Section 8(c) of the OSH Act, and help protect employees because such 
records contribute to the evaluation of employees' health and enable 
employees and their healthcare providers to make informed health care 
decisions. These records are especially important when an employee's 
medical condition places him or her at increased risk of health 
impairment from further exposure to respirable crystalline silica. 
Furthermore, the records can be used by the Agency and others to 
identify illnesses and deaths that may be attributable to respirable 
crystalline silica exposure, evaluate compliance programs, and assess 
the efficacy of the standard. OSHA concludes that medical surveillance 
records, like exposure records, are necessary and appropriate

[[Page 16855]]

for protection of employee health, enforcement of the standard, and 
development of information regarding the causes and prevention of 
occupational illnesses.
    Commenters, such as NISA and ASSE, addressed the issue of duration 
of retention of medical records (Document ID 2339, p. 10; 2195, p. 35). 
NISA indicated that 30 years is an appropriate retention period 
(Document ID 2195, p. 35). ASSE indicated that medical records should 
be retained for 40 years or the duration of the employment plus 20 
years, whichever is longer, due to latency periods of some silica-
related illnesses (Document ID 2339, p. 10).
    As with exposure records and objective data records, OSHA has 
concluded that the best approach is to maintain consistency with 29 CFR 
1910.1020 and its required retention period for medical records; that 
period is the duration of employment plus 30 years. It is necessary to 
keep medical records for this extended time period because of the long 
latency period between exposure and development of silica-related 
disease (45 FR at 35268-35271). OSHA recognizes that in some cases, the 
latency period for silica-related diseases may extend beyond 30 years. 
However, the Agency concludes that the retention period specified in 29 
CFR 1910.1020 represents a reasonable balance between the need to 
maintain records and the administrative burdens associated with 
maintaining those records for extended time periods. Because the 
duration of employment plus the 30-year records retention requirement 
is currently included in 29 CFR 1910.1020, this time period is 
consistent with longstanding Agency and employer practice.
    Charles Gordon, a retired occupational safety and health attorney, 
advocated for a provision for trade associations, unions, and medical 
practices to provide medical exams and keep medical records (Document 
ID 2163, Testimony 1, p. 14). After considering this suggestion, OSHA 
decided not to incorporate it into the rule. OSHA anticipates that, in 
some cases, employers may be able to work with unions or trade 
associations to ensure that medical examinations are provided that meet 
the requirements of the rule, and that records are maintained. However, 
in many cases, unions and trade associations will not be available to 
provide such services. And in any case, the employer is ultimately 
responsible for ensuring that medical examinations are provided in 
accordance with the rule. Consistent with OSHA's access to employee 
exposure and medical records standard (29 CFR 1910.1020), the rule 
therefore requires the employer to maintain such records, and the 
employer must ensure the PLHCP retains the medical records for the 
employee's duration of employment plus 30 years. As stated earlier, the 
employer can generally fulfill this obligation by including the 
retention requirement in the contractual agreement between the employer 
and the PLHCP.
    Commenters such as the International Union of Bricklayers and 
Allied Craftworkers (BAC) and ASSE stated that records should be made 
available to the employee and the employee's designated 
representative(s), at the request of the employee (e.g., Document ID 
2329, p. 8; 2339, p. 5). OSHA agrees, and employees and their 
representatives are permitted to obtain a copy of exposure and medical 
records pursuant to 29 CFR 1910.1020(e)(iii).
    Commenters such as the Building and Construction Trades Department, 
AFL-CIO (BCTD) and BAC requested the addition of a provision for 
retaining training records in the rule (e.g., Document ID 2371, 
Attachment 1, p. 50; 2329, p. 8). BAC recommended that employers in the 
construction industry could use a portable training management system 
that is designed to track employees' training throughout their career 
(Document ID 4053, Attachment 1 and Exhibit 2). To keep track of 
training records, BCTD recommended that employers could use the same 
portable training management system recommended by BAC or use a 
portable database, as described in a report by the Mount Sinai Irving 
J. Selikoff Center for Occupational and Environmental Medicine 
(Document ID 4223, p. 126; 4073, Attachment 2b).
    OSHA is not including a provision for retaining training records in 
the rule because the Agency has concluded that requiring such records 
is not necessary. The performance-oriented requirements for training in 
paragraph (j) of the standard for general industry and maritime 
(paragraph (i) of the standard for construction) specify that employees 
must be able to demonstrate knowledge of the health hazards associated 
with exposure to respirable crystalline silica; tasks that could result 
in exposure; procedures to protect employees from exposure; as well as 
the silica standard and the medical surveillance program it requires. 
These requirements will be sufficient to ensure that employees are 
adequately trained with regard to recognizing silica hazards and taking 
protective measures. Moreover, adding a provision for retention of 
training records would involve additional paperwork burdens for 
employers. The absence of a requirement for retention of training 
records in the rule is consistent with OSHA's hazard communication 
standard (29 CFR 1910.1200), addressing training for all hazardous 
chemicals, as well as the most recent OSHA substance-specific health 
standards, addressing exposure to 1,3-butadiene (29 CFR 1910.1051), 
methylene chloride (29 CFR 1910.1052), and chromium (VI) (29 CFR 
1910.1026).
    The recordkeeping requirements of the rule are also generally 
consistent with the recordkeeping provisions of the industry consensus 
standards, ASTM E 1132-06, Standard Practice for Health Requirements 
Relating to Occupational Exposure to Respirable Crystalline Silica and 
ASTM E 2625-09, Standard Practice for Controlling Occupational Exposure 
to Respirable Crystalline Silica for Construction and Demolition 
Activities. The main substantive differences are related to the use of 
social security numbers and duration of retention of records. ASTM E 
1132-06 and ASTM E 2625-09 specify that the employer should include an 
identification number for each employee monitored for dust exposure, 
but do not indicate that the number must be a social security number, 
whereas OSHA's rule requires the employer to include the employee's 
social security number. As noted above, although OSHA intends to 
reconsider this policy for all standards in a future rulemaking, the 
Agency has determined that the use of social security numbers is 
appropriate for this rule. ASTM E 1132-06 specifies that medical and 
exposure records should be retained for 40 years or the duration of 
employment plus 20 years, whichever is longer. ASTM E 2625-09 does not 
specify a duration for retaining exposure or medical records. OSHA has 
determined that the retention requirements of 29 CFR 1910.1020 are 
appropriate for exposure and medical records collected under this rule, 
because the requirements represent a reasonable balance between the 
need to maintain records and the administrative burdens associated with 
maintaining those records, and are consistent with longstanding 
practice by the Agency with which employers are familiar and to which 
they are accustomed; changing the duration of retention requirement for 
this one rule could therefore cause confusion.

Dates

    Paragraph (l) of the standard for general industry and maritime 
(paragraph (k) of the standard for construction) sets forth the 
effective date of the standard and the date(s) for

[[Page 16856]]

compliance with the requirements of the standard. OSHA proposed 
identical requirements for both standards: An effective date 60 days 
after publication of the rule; a date for compliance with all 
provisions except engineering controls and laboratory requirements of 
180 days after the effective date; a date for compliance with 
engineering controls requirements, which was one year after the 
effective date; and a date for compliance with laboratory requirements 
of two years after the effective date.
    The United Steelworkers supported the proposed effective and start-
up dates, arguing that they provide adequate time for employers to come 
into compliance with the rule (Document ID 2336, p. 16). Employers and 
industry representatives such as the American Exploration and 
Production Council, the Tile Council of North America, and Ameren 
requested that the effective date of the rule be extended (e.g., 
Document ID 2147, p. 2; 2267, p. 7; 2315, p. 4; 2375, Attachment 1, p. 
3; 2363 p. 7).
    OSHA sets the effective date to allow sufficient time for employers 
to obtain the standard, read and understand its requirements, and 
undertake the necessary planning and preparation for compliance. 
Section 6(b)(4) of the OSH Act allows the effective date of a standard 
to be delayed for up to 90 days from the date of publication in the 
Federal Register. Given the requests by commenters, OSHA's interest in 
having employers implement effective compliance efforts, and the 
minimal effect of an additional 30 day delay, the Agency has decided 
that it is appropriate to set the effective date at 90 days from 
publication, rather than at 60 days. Accordingly, the rule will become 
effective 90 days after publication in the Federal Register.
    Paragraphs (l)(2), (3) and (4) of the standard for general industry 
and maritime (paragraphs (k)(2) and (3) of the standard for 
construction) establish dates for compliance with the requirements of 
the standard. Employers and industry representatives such as the 
American Petroleum Institute, the National Industrial Sand Association, 
Dow Chemical Company, the Glass Association of North America (GANA), 
and the American Foundry Society (AFS) contended that substantially 
more time was needed to implement engineering controls than the one 
year from the effective date that had been proposed (e.g., Document ID 
2195, pp. 8, 22; 2147, p. 1; 2267, p. 3; 2149, p. 2; 2277, p. 1; 1992, 
pp. 4, 12; 2023, p. 4; 2315 pp. 4, 9; 2137; 2047; 2215, p. 10; 2311, p. 
3; 2291, p. 16; 2105. p. 1; 2348, Attachment 1, p. 40; 2357, p. 18; 
2365, pp. 10-22; 2301, Attachment 1, pp. 64, 82; 2302, p. 9; 2327, 
Attachment 1; 2270, p. 1; 2279, pp. 6, 11; 2290, pp. 3-4; 2296, p. 36; 
2384, p. 6; 2493, p. 5; 2379, Appendix 1, pp. 22, 73-74; 2544, p. 11).
    General industry employers and trade associations were concerned 
with the length of time needed for the design, approval, and 
installation of engineering controls. For example, the AFS provided 
examples of how implementation of engineering controls could take 
longer than one year for foundries:

    The proposed compliance period fails to account for the 
substantial time required for a comprehensive engineering evaluation 
of the overall silica exposure at the facility and the design of a 
proposed engineering control system. The engineering phase alone for 
a 10,000 cfm or larger system typically takes 4 to 6 months--longer 
for large or complex exposure problems. This issue is further 
complicated by the fact that the current national economy has 
substantially reduced the number of firms offering these 
environmental services, and all of the affected foundries will be 
competing for these limited services. The compliance period also 
fails to take into effect the fact that to attempt to meet the 
proposed PEL with local exhaust ventilation would require custom 
control equipment (primarily baghouses) which are not stock items 
and are custom built for each application. These control systems 
typically require a minimum of 2 to 4 months for manufacture after 
the completion of the engineering specifications and submission of 
an order. This period is significantly longer for specialized or 
large orders (Document ID 2379, Attachment B, p. 37).

    Another issue raised by general industry representatives and 
employers such as Morgan Electro Ceramics, the Asphalt Roofing 
Manufacturers Association, the Fertilizer Institute, and the National 
Association of Manufacturers, was the potential length of time involved 
in environmental permitting processes (e.g., Document ID 1772, p. 1; 
1992, Attachment 1, p. 4; 2291, Attachment 1, pp. 16-17; 3487, pp. 26-
27; 3492, Attachment 1, pp. 5-6; 3584, Tr. 2845; 2290, Attachment 1, p. 
3; 2380, Attachment 2, p. 20). The AFS testified on the permitting 
issue:

    Because many of the controls involve additions or changes to 
ventilation systems, OSHA must recognize the additional time 
required for modelling and permitting by state or federal EPA 
authorities. The proposed one year compliance period is totally 
unrealistic. In some states, the mandatory permitting requirement 
for both new and modified systems requires up to 18 months, and this 
does not include the design and modelling work necessary to prepare 
the permit application, or the construction and installation time 
after approval. For foundries which have a Title V permit, the 
approval includes an additional time period for the US EPA to review 
and make comments, and if the facility is subject to the federal 
Prevention of Significant Deterioration (PSD) or Lowest Achievable 
Emission Rate (LAER) rules the permit approval can take an 
additional 6 to 18 months for the detailed review and approval 
necessary (Document ID 3487, p. 26).

    OSHA is persuaded that the concerns expressed by commenters 
regarding the time needed to implement engineering controls are 
reasonable, and is extending the compliance deadline for general 
industry and maritime to allow two years from the effective date for 
employers to comply with the standard. In extending the proposed 
compliance date for engineering controls in the general industry and 
maritime standard by one year, OSHA has concluded that engineering 
controls can be implemented within two years of the effective date in 
most general industry and maritime workplaces. However, because permit 
requirements and application processes vary by jurisdiction, OSHA is 
willing to use its enforcement discretion in situations where an 
employer can show it has made good faith efforts to implement 
engineering controls, but has been unable to implement such controls 
due to the time needed for environmental permitting.
    OSHA understands that some general industry employers may face 
difficulties in implementing engineering controls due to continuous 
operation of facilities in particular industries. Trade associations 
such as the North American Insulation Manufacturers Association (NAIMA) 
and the GANA noted that their industries have plants that run 
constantly and shut down only on rare occasions, making installation of 
engineering controls, which would require a shutdown, unusually 
difficult and expensive (e.g., Document ID 2348, Attachment 1, p. 40; 
2215, Attachment 1, p. 10). OSHA is willing to provide latitude and 
work with such employers on an individual basis to schedule 
implementation of engineering controls during shutdowns, provided they 
are working in good faith toward compliance and that they provide and 
assure employees use appropriate respirators until engineering controls 
are installed.
    Paragraph (l)(3)(ii) of the standard for general industry and 
maritime allows five years from the effective date--four years more 
than the proposed standard--for employers to comply with obligations 
for engineering controls in hydraulic fracturing operations in the

[[Page 16857]]

oil and gas industry. Additional time is provided to implement 
engineering controls in this industry to allow employers to take 
advantage of further development of emerging technologies discussed in 
Chapter IV of the Final Economic Analysis and Final Regulatory 
Flexibility Analysis (FEA). Paragraph (l)(3)(iii) specifies that 
obligations for medical surveillance in paragraph (i)(l)(i) commence in 
accordance with paragraph (l)(4) for hydraulic fracturing operations in 
the oil and gas industry. Paragraph (l)(4) is discussed below.
    Paragraph (k)(2) of the standard for construction allows one year 
after the effective date to come into compliance with all obligations 
other than the requirements for methods of sample analysis. This 
extends the time (one year compared to 180 days) for compliance with 
the standard's ancillary provisions and retains the one year period 
after the effective date for engineering controls. Commenting on the 
proposed compliance dates for construction work, several stakeholders 
raised issues that might impact the ability of employers to implement 
engineering controls within one year after the effective date (e.g., 
Document ID 2296, Attachment 1, p. 36; 2357, p. 18). OSHA expects that 
the vast majority of construction employers will choose to implement 
the controls specified in paragraph (c) of the construction standard. 
These controls are generally commercial products that are readily 
available and can be purchased and put into use in a very short period 
of time. For the limited number of construction tasks that require more 
sophisticated controls (e.g., enclosed cabs on heavy equipment used 
during the demolition of concrete or masonry structures), the controls 
are already either commonly in use or could be implemented within one 
year. Moreover, by implementing the controls specified in paragraph (c) 
of the construction standard, employers will not be required to assess 
employee exposures to respirable crystalline silica, so no time will be 
needed for assessing employee exposures prior to implementing 
engineering controls. OSHA finds that the ready availability of 
engineering controls for construction will enable construction 
employers to implement engineering controls within one year of the 
effective date, and the Agency is therefore requiring that construction 
employers implement engineering controls required by the standard 
within one year of the effective date.
    In requiring that general industry and maritime employers comply 
with most obligations of the standard two years after the effective 
date, and in requiring that construction employers comply with all 
ancillary and engineering controls one year after the effective date, 
OSHA has aligned the compliance dates for other provisions of the 
standards with the compliance dates for engineering controls. This will 
allow employers to focus their efforts on implementation of engineering 
controls. OSHA decided that staggering the compliance dates for some 
provisions of the rule could serve to divert attention and resources 
away from the implementation of engineering controls. For example, if 
respiratory protection were to be required six months after the 
effective date (as OSHA proposed), employers would need to assess 
employee exposures, and would need to develop a respiratory protection 
program and provide appropriate respirators to employees exposed above 
the PEL, while simultaneously working to implement engineering 
controls. A requirement for respiratory protection prior to 
implementation of engineering controls would be particularly 
problematic where construction employers implement the controls 
specified in paragraph (c) of the construction standard. This is 
because those employers would not otherwise be required to assess 
employee exposures.
    In determining the compliance dates for provisions other than 
engineering controls, OSHA considered the relatively short time period 
before engineering controls must be implemented in construction work. 
The Agency recognizes the longer time period allowed for general 
industry and maritime employers to implement engineering controls. 
However, general industry employers must comply with a PEL that is 
approximately equivalent to 100 [mu]g/m\3\ during the period before 
compliance with the revised PEL of 50 [mu]g/m\3\ is required, whereas 
construction work will be subject to a higher PEL of approximately 250 
[mu]g/m\3\. The lower PEL of approximately 100 [mu]g/m\3\ that will 
apply to general industry will mitigate respirable crystalline silica 
exposures in this sector to some extent during the interim period. 
Moreover, because employers will be using this time to implement 
engineering controls, OSHA expects that exposures will continue to 
decline during this period. Construction will continue to be subject to 
the higher PEL of approximately 250 [mu]g/m\3\ during this interim, but 
that period will only be one year from the effective date, compared to 
two years from the effective date for general industry and maritime. 
OSHA finds that establishing consistent compliance dates for 
engineering controls and other provisions of the standards is less 
confusing, more practical, and will better enable employers to focus 
their time and resources on implementing the control measures that will 
best protect employees. For hydraulic fracturing operations in the oil 
and gas industry, OSHA is providing an extra three years--a total of 
five years from the effective date--for employers to implement 
engineering controls for hydraulic fracturing operations. During these 
additional three years, employers must comply with all other 
requirements of the standard, including requirements for respiratory 
protection to protect employees exposed to respirable crystalline 
silica at levels that exceed the revised PEL of 50 [mu]g/m\3\.
    The issue of how much time to allow for laboratories to come into 
compliance with respect to methods of sample analysis received 
considerable comment during the rulemaking. Employers and trade and 
professional associations such as the National Tile Contractors 
Association, the Fertilizer Institute, OSCO Industries, Edison Electric 
Institute, and Fann Contracting, Inc. expressed concerns about the 
proposed rule's provisions that gave all employers one year to 
implement engineering controls and allowed two years before employers 
would be required to follow requirements for methods of sample analysis 
(e.g., Document ID 2267, pp. 6-7; 2149, p. 2; 1992, pp. 10, 12; 2179, 
p. 3; 2312, p. 2; 2317, p. 2; 2314, p. 3; 2357, pp. 18-19; 2365, p. 22; 
2116, Attachment 1, p. 48; 2327, p. 29; 2368, p. 3; 2379, Attachment B, 
p. 37; 3398, pp. 1-2; 3487, p. 27; 3491, p. 5; 2363, p. 6). For 
example, Andy Fulton of ME Global stated:

    OSHA is giving laboratories 2 years to improve their procedures 
for accurate silica analysis. However, OSHA is requiring foundries 
to install expensive engineering controls within one year, before 
accurate exposure levels are available. This does not make sense, 
especially when it could involve millions of dollars (Document ID 
2149, p. 2).

    In proposing to require employers to implement engineering controls 
and comply with other provisions of the rule before the laboratory 
requirements came into effect, OSHA intended to allow time for 
laboratory capacity to develop. As indicated in Chapter IV of the FEA, 
OSHA finds that it is feasible to measure exposures to respirable 
crystalline silica at the revised PEL and action level with a 
reasonable degree of accuracy and precision using methods that are 
currently available. Many laboratories are capable of analyzing samples 
in accordance with the laboratory requirements of the silica rule; OSHA

[[Page 16858]]

encourages employers to follow these requirements prior to the time 
that they are mandated. There are approximately 40 laboratories that 
are accredited by AIHA Laboratory Accreditation Programs for the 
analysis of crystalline silica (Document ID 3586, Tr. 3284). These 
laboratories are already capable of analyzing samples in accordance 
with the laboratory requirements of the silica rule.
    OSHA anticipates that the additional demand for respirable 
crystalline silica exposure monitoring and associated laboratory 
analysis with the rule will be modest. Most construction employers are 
expected to implement the specified exposure control measures in 
paragraph (c) of the construction standard, and will therefore not be 
required to assess employee exposures, thus placing no demands on 
laboratories. The performance option for exposure assessment provided 
in both the general industry and maritime standard at paragraph (d)(2) 
and the construction standard at paragraph (d)(2)(ii) also serves to 
lessen the anticipated volume of exposure monitoring. The additional 
time allowed for compliance with the general industry and maritime 
standard further serves to diminish concerns about laboratory capacity 
by providing additional time for laboratory capacity to increase and 
distributing demand for sample analysis over an extended period of 
time. OSHA therefore concludes that the compliance date for methods of 
sample analysis of two years after the effective date is reasonable in 
both the general industry/maritime and construction standards. OSHA 
also anticipates that construction employers who perform air monitoring 
before the laboratory requirements go into effect (see paragraph (k)(3) 
of the construction standard) will be able to obtain reliable 
measurements of their employees' exposures to respirable crystalline 
silica.
    Paragraph (l)(4) of the standard for general industry and maritime 
specifies that obligations in paragraph (i)(1)(i) regarding medical 
surveillance take effect for employees who will be occupationally 
exposed to respirable crystalline silica above the PEL for 30 or more 
days per year beginning two years after the effective date. Obligations 
in paragraph (i)(l)(i) for employees who will be occupationally exposed 
to respirable crystalline silica at or above the action level (but at 
or below the PEL) for 30 or more days per year will commence four years 
after the effective date. In other words, medical surveillance will be 
triggered by exposures above the PEL for 30 or more days per year, 
beginning two years after the effective date and continuing through 
four years after the effective date, and will then be triggered by 
exposures at or above the action level for 30 or more days per year 
beginning four years after the effective date. As indicated in the 
Summary and Explanation for Medical Surveillance, this approach focuses 
initial medical surveillance efforts on those employees who are at 
greatest risk, while giving most employers additional time to fully 
evaluate the engineering controls they have implemented in order to 
determine which employees meet the action level trigger for medical 
surveillance.
    Commenters such as NAIMA and the National Concrete Masonry 
Association voiced concerns about the proposed rule's effects on small 
businesses, and asked for compliance extensions for small businesses 
(e.g., Document ID 2348, Attachment 1, p. 41; 2279, Attachment 1, p. 
10). OSHA has considered these concerns, and has found that the 
compliance dates set forth in this section are reasonable for employers 
of all sizes. Therefore, OSHA has not created exceptions extending the 
compliance period for specific business classes or sizes.
    OSHA also considered comments from the U.S. Chamber of Commerce and 
the National Stone, Sand, and Gravel Association, among others, 
expressing concern that the rule would create increased demand for 
health and safety professionals and for medical professionals; they 
alleged there are not enough professionals in those fields to service 
the demand that would be created by the rule (e.g., Document ID 2365, 
Attachment 1, p. 10; 2237, Attachment 1, p. 4; 3578, Tr. 1127). The 
Agency does not find these arguments convincing. Most of the provisions 
of the rule do not generally require the involvement of a health or 
safety professional, or require only limited oversight from a health or 
safety professional. For example, exposure monitoring does not need to 
be performed by certified industrial hygienists; technicians and other 
trained employees can perform this task. Employer compliance with the 
specified exposure control methods in paragraph (c) of the construction 
standard can generally be accomplished without the involvement of a 
health or safety professional. Compliance with other obligations, such 
as housekeeping and training requirements, can also be achieved without 
the involvement of a health or safety professional or with minimal 
oversight from them. There are a sufficient number of medical 
professionals available for employers to implement the medical 
surveillance provisions of the rule. The availability of medical 
professionals is confirmed and discussed in detail in the summary and 
explanation of Medical Surveillance in this preamble. Therefore, the 
Agency finds no evidence in the record that a shortage of available 
health and safety professionals, or a shortage of medical 
professionals, will preclude employers from complying with the rule by 
the dates set forth in this paragraph.
    Thus, the effect of changes made to the proposed rule is that: (1) 
All obligations (i.e., exposure assessment and other ancillary 
provisions, engineering controls) for general industry and maritime 
employers (other than hydraulic fracturing operations in the oil and 
gas industry and an action level trigger for medical surveillance for 
all general industry and maritime employers) will become enforceable 
two years after the 90-day effective date of the rule; (2) all 
obligations for hydraulic fracturing operations in the oil and gas 
industry (except obligations for engineering controls and an action 
level trigger for medical surveillance) will become enforceable two 
years after the 90-day effective date; (3) obligations for engineering 
controls for hydraulic fracturing operations in the oil and gas 
industry will become enforceable five years after the 90-day effective 
date; (4) obligations for an action level trigger for medical 
surveillance in the standard for general industry and maritime, 
including hydraulic fracturing operations in the oil and gas industry, 
will become enforceable four years after the 90-day effective date; (5) 
all obligations (other than requirements for methods of sample 
analysis) for construction employers will become enforceable one year 
after the 90-day effective date; and (6) requirements for methods of 
sample analysis, applicable to laboratories covered by paragraph 
(d)(2)(v) of the standard for construction, become enforceable two 
years after the effective date, i.e., one year after the other 
requirements in the construction standard and on the same date as all 
obligations in general industry and maritime (other than hydraulic 
fracturing).

Appendix A to Sec.  1910.1053 and Sec.  1926.1153--Methods of Sample 
Analysis

    Appendix A, which specifies methods of sample analysis, is included 
as part of each standard, 29 CFR 1910.1053 and 29 CFR 1926.1153. 
Employers must ensure that all samples taken to satisfy monitoring 
requirements of the standards are evaluated by a laboratory that 
analyzes air samples for respirable crystalline silica in accordance 
with the

[[Page 16859]]

procedures in Appendix A (paragraph (d)(5) of the standard for general 
industry and maritime and paragraph (d)(2)(v) of the standard for 
construction).
    OSHA proposed analysis requirements that it had included as part of 
paragraph (d) of both standards. The Southern Company recommended that 
OSHA require use of accredited laboratories and move all other 
laboratory requirements to an Appendix as a guide for laboratories that 
analyze silica samples (Document ID 2185, p. 7).
    OSHA has retained the substance of the proposed provisions 
addressing analysis of samples, but has moved these provisions to a new 
appendix in each standard. The Agency has decided that segregating 
these specifications in an appendix to each final standard provides 
greater clarity for both employers and the laboratories that analyze 
samples.
    Appendix A specifies procedures for the laboratories conducting the 
analysis, but employers must ensure samples taken to satisfy the 
monitoring requirements of the standard are analyzed by an accredited 
laboratory using the methods and quality control procedures described 
in this Appendix. Putting the requirements in a separate appendix, 
rather than in the regulatory text, facilitates the communication of 
these requirements to the laboratory analyzing samples. The appendix 
approach is also meant to clarify that an employer who engages a 
laboratory to analyze respirable crystalline silica samples may rely on 
an assurance from that laboratory that the specified requirements were 
met. For example, the laboratory could include a statement that it 
complied with the requirements of the standard along with the sampling 
results provided to the employer, or the employer could obtain the 
information from the laboratory or industrial hygiene service provider.
    Appendix A to the final standards describes the specific analytical 
methods to be used, as well as the qualifications of the laboratories 
at which the samples are analyzed. As discussed in greater detail in 
Chapter IV of the Final Economic Analysis and Final Regulatory 
Flexibility Analysis (FEA), the sampling and analysis methods required 
by the rule are technologically feasible in that they are widely used 
and accepted as the best available methods for measuring individual 
exposures to respirable crystalline silica. The Agency has determined 
that the provisions in Appendix A are needed to ensure the accuracy of 
monitoring required by the rule to measure employee exposures.
    OSHA has typically included specifications for the accuracy of 
exposure monitoring methods in substance-specific standards, but has 
not always specified the analytical methods to be used or the 
qualifications of the laboratory that analyzes the samples. Exceptions 
are the asbestos standards for general industry (29 CFR 1910.1001, 
Appendix A) and construction (29 CFR 1926.1101, Appendix A), which 
specify the sampling and analytical methods to be used, as well as 
quality control procedures to be implemented by laboratories.
    Consistent with the evaluation of sampling and analysis methods in 
the FEA, under the Appendix (A.1), all samples taken to satisfy the 
monitoring requirements of this section must be evaluated using the 
procedures specified in one of the following analytical methods: OSHA 
ID-142; NMAM 7500, NMAM 7602; NMAM 7603; MSHA P-2; or MSHA P-7. OSHA 
has determined based on inter-laboratory comparisons that laboratory 
analysis by either X-ray diffraction (XRD) or infrared (IR) 
spectroscopy is required to ensure the accuracy of the monitoring 
results. The specified analytical methods are the XRD or IR methods for 
analysis of respirable crystalline silica that have been established by 
OSHA, NIOSH, or MSHA.
    To ensure the accuracy of air sampling data relied on by employers 
to achieve compliance with the standard, the standard requires that 
employers must have air samples analyzed only at laboratories that meet 
requirements listed in A.2 through A.6.3. The requirements were 
developed based on recommendations for quality control procedures to 
improve agreement in analytical results obtained by laboratories (Eller 
et al., 1999, Document ID 1688, pp. 23-24). According to Dr. Rosa Key-
Schwartz, NIOSH's expert in crystalline silica analysis, NIOSH worked 
closely with AIHA Laboratory Accreditation Programs to implement a 
silica emphasis program for site visitors who audit accredited 
laboratories to ensure that these quality control procedures are being 
followed (Document ID 3579, Tr. 153). As discussed in the FEA, analysis 
of recent data from the AIHA Proficiency Analytical Testing (PAT) 
program showed that laboratory performance has improved in recent 
years, resulting in greater agreement between labs, and this has been 
attributed to improvement in quality control procedures (Document ID 
3998, Attachment 8; see also Section IV of the FEA).
    A.2 requires employers to ensure that samples taken to monitor 
employee exposures are analyzed by a laboratory that is accredited to 
ANS/ISO/IEC Standard 17025 ``General requirements for the competence of 
testing and calibration laboratories'' (EN ISO/IEC 17025:2005) by an 
accrediting organization that can demonstrate compliance with the 
requirements of ISO/IEC 17011 ``Conformity assessment--General 
requirements for accreditation bodies accrediting conformity assessment 
bodies'' (EN ISO/IEC 17011:2004). ANS/ISO/IEC 17025 is a consensus 
standard that was developed by the International Organization for 
Standardization and the International Electrotechnical Commission (ISO/
IEC) and approved by the American Society for Testing and Materials 
(ASTM). This standard establishes criteria by which laboratories can 
demonstrate proficiency in conducting laboratory analysis through the 
implementation of quality control measures. To demonstrate competence, 
laboratories must implement a quality control (QC) program that 
evaluates analytical uncertainty and provides employers with estimates 
of sampling and analytical error (SAE) when reporting samples. ISO/IEC 
17011 establishes criteria for organizations that accredit laboratories 
under ISO/IEC 17025. For example, the AIHA accredits laboratories for 
proficiency in the analysis of crystalline silica using criteria based 
on the ISO 17025 and other criteria appropriate for the scope of the 
accreditation.
    Appendix A.3-A.6.3 contain additional quality control procedures 
for laboratories that have been demonstrated to improve accuracy and 
reliability through inter-laboratory comparisons. The proposed rule 
would have required that laboratories participate in a round robin 
testing program with at least two other independent laboratories at 
least every six months. OSHA deleted this requirement in the final rule 
since accredited laboratories must participate in the AIHA PAT program. 
The laboratory must use the most current National Institute of 
Standards and Technology (NIST) or NIST-traceable standards for 
instrument calibration or instrument calibration verification (Appendix 
A.3). The laboratory must have an internal quality control (QC) program 
that evaluates analytical uncertainty and provides employers with 
estimates of sampling and analytical error (Appendix A.4). The

[[Page 16860]]

laboratory must characterize the sample material by identifying 
polymorphs of respirable crystalline silica present, identifying the 
presence of any interfering compounds that might affect the analysis, 
and making the corrections necessary in order to obtain accurate sample 
analysis (Appendix A.5). The laboratory must analyze quantitatively for 
respirable crystalline silica only after confirming that the sample 
matrix is free of uncorrectable analytical interferences, and corrects 
for analytical interferences (Appendix A.6). The laboratory must 
perform routine calibration checks with standards that bracket the 
sample concentrations using five or more calibration standard levels to 
prepare calibration curves, and use instruments optimized to obtain a 
quantitative limit of detection that represents a value no higher than 
25 percent of the PEL (Appendix A.6.1-A.6.3).
    Several stakeholders commented that requiring employers to analyze 
samples for all polymorphs (e.g., quartz, cristobalite, tridymite) 
would be unnecessarily burdensome, especially where the employer knows 
that some polymorphs are not present in its operations (Document ID 
2215, p. 9; 2291, p. 24; 2348, Attachment 1, pp. 33-34; 4213, p. 4; 
3588, Tr. 3968). OSHA does not intend for A.5 to require analysis for 
all polymorphs for every sample. Employers can consult with their 
laboratories or industrial hygiene service providers to determine which 
polymorphs are likely to be present in a sample given the nature of the 
material and processes employed. For example, if a material used by an 
employer is known to contain only quartz, and that material is not 
subjected to high temperatures, it is unlikely that cristobalite is 
present. Likewise, if prior sampling results failed to find 
cristobalite in airborne dust, there would be no need to analyze 
samples for cristobalite on a continuing basis. OSHA expects that 
laboratories and industrial hygiene service providers will be able to 
guide employers on the sample analyses necessary to ensure compliance 
with the rule without having to incur unnecessary analytical costs.

Appendix B to Sec.  1910.1053 and Sec.  1926.1153--Medical Surveillance

    Appendix B of each standard, 29 CFR 1910.1053 and 29 CFR 1926.1153, 
contains medical surveillance guidelines to assist in complying with 
the medical surveillance provisions and provides other helpful 
recommendations and information. Appendix B is for informational and 
guidance purposes only and none of the statements in Appendix B should 
be construed as imposing a mandatory requirement on employers that is 
not otherwise imposed by the standard. In addition, this appendix is 
not intended to detract from any obligation that the rule imposes. 
American College of Occupational Medicine (ACOEM), National Institute 
for Occupational Safety and Health (NIOSH), American Public Health 
Association, and the National Consumers League supported the inclusion 
of an appendix for medical surveillance guidelines (Document ID 2080, 
p. 2; 2177, Attachment B, p. 41; 2178, Attachment 1, p. 4; 2373, p. 4).
    The medical surveillance guidelines were in Appendix A of each 
proposed standard but were moved to Appendix B of the final standards, 
following the addition of Appendix A for methods of sample analysis. 
OSHA received some comments recommending corrections or clarifications 
to Appendix B. For example, NIOSH and the National Industrial Sand 
Association requested that OSHA update the discussion of digital 
radiography to include the most recent International Labour Office 
policy, as was done in the preamble, and NIOSH suggested several 
clarifications to the discussions on silicosis, specialists and 
specialist referrals, and tuberculosis (Document ID 2177, Attachment B, 
pp. 41, 48-50; 2195, pp. 44, 46). OSHA considered those comments and 
made changes as needed. In addition, OSHA revised Appendix B to make it 
consistent with the updates to the rule.
    American Federation of Labor and Congress of Industrial 
Organizations (AFL-CIO) requested that the appendix discuss medical 
confidentiality and provide guidance on information that may be 
provided to the employer without the employee's informed consent 
(Document ID 4204, p. 90). OSHA agrees that it is important to discuss 
this type of information in Appendix B because the information that the 
physician or licensed health care professional (PLHCP) is to provide to 
the employer under the standards has changed substantially from the 
proposal, and Appendix B may serve as the PLHCP's primary source of 
information about medical surveillance under the standards. Therefore 
OSHA has included a discussion on medical confidentiality. In addition, 
OSHA has included examples of the PLHCP's written medical report for 
the employee, the PLHCP's written medical opinion for the employer, and 
an authorization form to allow limitations on respirable crystalline 
silica exposure or recommendations for a specialist examination to be 
reported to the employer. OSHA expects the example report, opinion, and 
authorization form will greatly clarify the type of information that is 
to be reported to the employer.
    Some commenters requested that additional information be added to 
the appendix. ACOEM, NIOSH and Building and Construction Trades 
Department, AFL-CIO requested that the appendix include spirometry 
guidelines or reference values (Document ID 2080, p. 9; 2177, 
Attachment B, pp. 45-46; 4223, pp. 128-130). Collegium Ramazzini 
requested that the appendix include a standardized medical and exposure 
history (Document ID 3541, pp. 3, 6). AFL-CIO recommended that the 
appendix include a discussion on low dose computed tomography (LDCT) 
screening for lung cancer (Document ID, 4204, p. 82). OSHA is not 
including the information requested by these commenters in Appendix B 
for reasons discussed more fully in the summary and explanation for 
Medical Surveillance. OSHA is not including spirometry guidance because 
of the widespread availability of useful guidance, including an OSHA 
spirometry guidance available through OSHA's Web site. Instead of 
including a standardized medical and exposure history form, Appendix B 
includes a discussion of the information to be collected as part of a 
history that will allow PLHCPs to easily update their current history 
forms. Appendix B also does not include a discussion about LDCT 
screening for lung cancer because too little is currently known about 
the risks and benefits of such screening for employees exposed to 
respirable crystalline silica.

List of Subjects in 29 CFR Parts 1910, 1915, and 1926

    Cancer, Chemicals, Cristobalite, Crystalline silica, Hazardous 
substances, Health, Lung Diseases, Occupational safety and health, 
Quartz, Reporting and recordkeeping requirements, Silica, Silicosis, 
Tridymite.

Authority and Signature

    This document was prepared under the direction of David Michaels, 
Ph.D., MPH, Assistant Secretary of Labor for Occupational Safety and 
Health, U.S. Department of Labor, 200 Constitution Avenue NW., 
Washington, DC 20210.
    The Agency issues the sections under the following authorities: 
Sections 4, 6, and 8 of the Occupational Safety and Health Act of 1970 
(29 U.S.C. 653, 655, 657); section 107 of the Contract Work

[[Page 16861]]

Hours and Safety Standards Act (the Construction Safety Act) (40 U.S.C. 
3704); section 41 of the Longshore and Harbor Worker's Compensation Act 
(33 U.S.C. 941); Secretary of Labor's Order 1-2012 (77 FR 3912 (1/25/
2012)); and 29 CFR part 1911.

David Michaels,
Assistant Secretary of Labor for Occupational Safety and Health.

Amendments to Standards

    For the reasons set forth in the preamble, 29 CFR parts 1910, 1915, 
and 1926, of the Code of Federal Regulations are amended as follows:

PART 1910--OCCUPATIONAL SAFETY AND HEALTH STANDARDS

Subpart Z--[Amended]

0
1. The authority citation for subpart Z of part 1910 is revised to read 
as follows:

    Authority: Secs. 4, 6, 8 of the Occupational Safety and Health 
Act of 1970 (29 U.S.C. 653, 655, 657); Secretary of Labor's Order 
No. 12-71 (36 FR 8754), 8-76 (41 FR 25059), 9-83 (48 FR 35736), 1-90 
(55 FR 9033), 6-96 (62 FR 111), 3-2000 (65 FR 50017), 5-2002 (67 FR 
65008), 5-2007 (72 FR 31160), 4-2010 (75 FR 55355), or 1-2012 (77 FR 
3912), as applicable; and 29 CFR part 1911. All of subpart Z issued 
under section 6(b) of the Occupational Safety and Health Act of 
1970, except those substances that have exposure limits listed in 
Tables Z-1, Z-2, and Z-3 of 29 CFR 1910.1000. The latter were issued 
under section 6(a) (29 U.S.C. 655(a)).
    Section 1910.1000, Tables Z-1, Z-2 and Z-3 also issued under 5 
U.S.C. 553, but not under 29 CFR part 1911 except for the arsenic 
(organic compounds), benzene, cotton dust, and chromium (VI) 
listings.
    Section 1910.1001 also issued under section 107 of the Contract 
Work Hours and Safety Standards Act (40 U.S.C. 3704) and 5 U.S.C. 
553.
    Section 1910.1002 also issued under 5 U.S.C. 553, but not under 
29 U.S.C. 655 or 29 CFR part 1911.
    Sections 1910.1018, 1910.1029, and 1910.1200 also issued under 
29 U.S.C. 653.
    Section 1910.1030 also issued under Pub. L. 106-430, 114 Stat. 
1901.
    Section 1910.1201 also issued under 49 U.S.C. 1801-1819 and 5 
U.S.C. 553.

0
2. In Sec.  1910.1000, paragraph (e):
0
a. Amend Table Z-1--Limits on Air Contaminants by:
0
i. Revising the entries for ``Silica, crystalline cristobalite, 
respirable dust''; ``Silica, crystalline quartz, respirable dust''; 
Silica, crystalline tripoli (as quartz), respirable dust''; and 
``Silica, crystalline tridymite, respirable dust''; and
0
ii. Adding footnote 7.
0
b. Amend Table Z-3-Mineral Dusts by:
0
i. Revising the entries for ``Silica: Crystalline Quartz 
(Respirable)'', ``Silica: Crystalline Cristobalite'', and ``Silica: 
Crystalline Tridymite'';
0
ii. Removing entries in columns 1, 2, and 3 for ``Silica: Crystalline 
Quartz (Total Dust)'' and
0
iii. Adding footnote f.
    The revisions and addition read as follows:


Sec.  1910.1000  Air contaminants.

* * * * *
    The revisions and addition read as follows:


Sec.  1910.1000  Air contaminants.

* * * * *

                                     Table Z-1--Limits for Air Contaminants
----------------------------------------------------------------------------------------------------------------
                                                                                                       Skin
                    Substance                       CAS No. (c)     ppm(a) \1\    mg/m\3\(b) \1\    designation
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
Silica, crystalline, respirable dust
    Cristobalite; see 1910.1053 \7\.............      14464-46-1  ..............  ..............  ..............
    Quartz; see 1910.1053 \7\...................      14808-60-7  ..............  ..............  ..............
    Tripoli (as quartz); see 1910.1053 \7\......       1317-95-9  ..............  ..............  ..............
    Tridymite; see 1910.1053 \7\................      15468-32-3  ..............  ..............  ..............
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
* * * * * * *
\1\ The PELs are 8-hour TWAs unless otherwise noted; a (C) designation denotes a ceiling limit. They are to be
  determined from breathing-zone air samples.
(a) Parts of vapor or gas per million parts of contaminated air by volume at 25 [deg]C and 760 torr.
(b) Milligrams of substance per cubic meter of air. When entry is in this column only, the value is exact; when
  listed with a ppm entry, it is approximate.
(c) The CAS number is for information only. Enforcement is based on the substance name. For an entry covering
  more than one metal compound, measured as the metal, the CAS number for the metal is given--not CAS numbers
  for the individual compounds.
(d) The final benzene standard in 1910.1028 applies to all occupational exposures to benzene except in some
  circumstances the distribution and sale of fuels, sealed containers and pipelines, coke production, oil and
  gas drilling and production, natural gas processing, and the percentage exclusion for liquid mixtures; for the
  excepted subsegments, the benzene limits in Table Z-2 apply. See 1910.1028 for specific circumstances.
(e) This 8-hour TWA applies to respirable dust as measured by a vertical elutriator cotton dust sampler or
  equivalent instrument. The time-weighted average applies to the cottom waste processing operations of waste
  recycling (sorting, blending, cleaning and willowing) and garnetting. See also 1910.1043 for cotton dust
  limits applicable to other sectors.
(f) All inert or nuisance dusts, whether mineral, inorganic, or organic, not listed specifically by substance
  name are covered by the Particulates Not Otherwise Regulated (PNOR) limit which is the same as the inert or
  nuisance dust limit of Table Z-3.
 * * * * * * *
\3\ See Table Z-3.
 * * * * * * *
\7\ See Table Z-3 for the exposure limit for any operations or sectors where the exposure limit in Sec.
  1910.1053 is stayed or is otherwise not in effect.
 * * * * * * *


                        Table Z-3--Mineral Dusts
------------------------------------------------------------------------
                Substance                    mppcf \a\        mg/m\3\
------------------------------------------------------------------------
Silica:                                   ..............  ..............
Crystalline                               ..............  ..............

[[Page 16862]]

 
    Quartz (Respirable) \f\.............         250 \b\  10 mg/m\3\ \e\
                                                 %SiO2+5        % SiO2+2
Cristobalite: Use \1/2\ the value         ..............  ..............
 calculated from the count or mass
 formulae for quartz \f\
Tridymite: Use \1/2\ the value            ..............  ..............
 calculated from the formulae for quartz
 \f\....................................
 
                              * * * * * * *
------------------------------------------------------------------------
 * * * * * * *
\a\ Millions of particles per cubic foot of air, based on impinger
  samples counted by light-field techniques.
\b\ The percentage of crystalline silica in the formula is the amount
  determined from airborne samples, except in those instances in which
  other methods have been shown to be applicable.
 * * * * * * *
\e\ Both concentration and percent quartz for the application of this
  limit are to be determined from the fraction passing a size-selector
  with the following characteristics:


------------------------------------------------------------------------
                                                     Percent passing
  Aerodynamic diameter  (unit density sphere)            selector
------------------------------------------------------------------------
2..............................................                       90
2.5............................................                       75
3.5............................................                       50
5.0............................................                       25
10.............................................                        0
------------------------------------------------------------------------
The measurements under this note refer to the use of an AEC (now NRC)
  instrument. The respirable fraction of coal dust is determined with an
  MRE; the figure corresponding to that of 2.4 mg/m\3\ in the table for
  coal dust is 4.5 mg/m\3K\.
\f\ This standard applies to any operations or sectors for which the
  respirable crystalline silica standard, 1910.1053, is stayed or is
  otherwise not in effect.

0
4. Add Sec.  1910.1053 to read as follows:


Sec.  1910.1053  Respirable Crystalline Silica.

    (a) Scope and application. (1) This section applies to all 
occupational exposures to respirable crystalline silica, except:
    (i) Construction work as defined in 29 CFR 1910.12(b) (occupational 
exposures to respirable crystalline silica in construction work are 
covered under 29 CFR 1926.1153);
    (ii) Agricultural operations covered under 29 CFR part 1928; and
    (iii) Exposures that result from the processing of sorptive clays.
    (2) This section does not apply where the employer has objective 
data demonstrating that employee exposure to respirable crystalline 
silica will remain below 25 micrograms per cubic meter of air (25 
[mu]g/m\3\) as an 8-hour time-weighted average (TWA) under any 
foreseeable conditions.
    (3) This section does not apply if the employer complies with 29 
CFR 1926.1153 and:
    (i) The task performed is indistinguishable from a construction 
task listed on Table 1 in paragraph (c) of 29 CFR 1926.1153; and
    (ii) The task will not be performed regularly in the same 
environment and conditions.
    (b) Definitions. For the purposes of this section the following 
definitions apply:
    Action level means a concentration of airborne respirable 
crystalline silica of 25 [mu]g/m\3\, calculated as an 8-hour TWA.
    Assistant Secretary means the Assistant Secretary of Labor for 
Occupational Safety and Health, U.S. Department of Labor, or designee.
    Director means the Director of the National Institute for 
Occupational Safety and Health (NIOSH), U.S. Department of Health and 
Human Services, or designee.
    Employee exposure means the exposure to airborne respirable 
crystalline silica that would occur if the employee were not using a 
respirator.
    High-efficiency particulate air [HEPA] filter means a filter that 
is at least 99.97 percent efficient in removing mono-dispersed 
particles of 0.3 micrometers in diameter.
    Objective data means information, such as air monitoring data from 
industry-wide surveys or calculations based on the composition of a 
substance, demonstrating employee exposure to respirable crystalline 
silica associated with a particular product or material or a specific 
process, task, or activity. The data must reflect workplace conditions 
closely resembling or with a higher exposure potential than the 
processes, types of material, control methods, work practices, and 
environmental conditions in the employer's current operations.
    Physician or other licensed health care professional [PLHCP] means 
an individual whose legally permitted scope of practice (i.e., license, 
registration, or certification) allows him or her to independently 
provide or be delegated the responsibility to provide some or all of 
the particular health care services required by paragraph (i) of this 
section.
    Regulated area means an area, demarcated by the employer, where an 
employee's exposure to airborne concentrations of respirable 
crystalline silica exceeds, or can reasonably be expected to exceed, 
the PEL.
    Respirable crystalline silica means quartz, cristobalite, and/or 
tridymite contained in airborne particles that are determined to be 
respirable by a sampling device designed to meet the characteristics 
for respirable-particle-size-selective samplers specified in the 
International Organization for Standardization (ISO) 7708:1995: Air 
Quality--Particle Size Fraction Definitions for Health-Related 
Sampling.
    Specialist means an American Board Certified Specialist in 
Pulmonary Disease or an American Board Certified Specialist in 
Occupational Medicine.
    This section means this respirable crystalline silica standard, 29 
CFR 1910.1053.
    (c) Permissible exposure limit (PEL). The employer shall ensure 
that no employee is exposed to an airborne concentration of respirable 
crystalline silica in excess of 50 [mu]g/m\3\, calculated as an 8-hour 
TWA.
    (d) Exposure assessment--(1) General. The employer shall assess the 
exposure of each employee who is or may reasonably be expected to be 
exposed to respirable crystalline silica at or above

[[Page 16863]]

the action level in accordance with either the performance option in 
paragraph (d)(2) or the scheduled monitoring option in paragraph (d)(3) 
of this section.
    (2) Performance option. The employer shall assess the 8-hour TWA 
exposure for each employee on the basis of any combination of air 
monitoring data or objective data sufficient to accurately characterize 
employee exposures to respirable crystalline silica.
    (3) Scheduled monitoring option. (i) The employer shall perform 
initial monitoring to assess the 8-hour TWA exposure for each employee 
on the basis of one or more personal breathing zone air samples that 
reflect the exposures of employees on each shift, for each job 
classification, in each work area. Where several employees perform the 
same tasks on the same shift and in the same work area, the employer 
may sample a representative fraction of these employees in order to 
meet this requirement. In representative sampling, the employer shall 
sample the employee(s) who are expected to have the highest exposure to 
respirable crystalline silica.
    (ii) If initial monitoring indicates that employee exposures are 
below the action level, the employer may discontinue monitoring for 
those employees whose exposures are represented by such monitoring.
    (iii) Where the most recent exposure monitoring indicates that 
employee exposures are at or above the action level but at or below the 
PEL, the employer shall repeat such monitoring within six months of the 
most recent monitoring.
    (iv) Where the most recent exposure monitoring indicates that 
employee exposures are above the PEL, the employer shall repeat such 
monitoring within three months of the most recent monitoring.
    (v) Where the most recent (non-initial) exposure monitoring 
indicates that employee exposures are below the action level, the 
employer shall repeat such monitoring within six months of the most 
recent monitoring until two consecutive measurements, taken 7 or more 
days apart, are below the action level, at which time the employer may 
discontinue monitoring for those employees whose exposures are 
represented by such monitoring, except as otherwise provided in 
paragraph (d)(4) of this section.
    (4) Reassessment of exposures. The employer shall reassess 
exposures whenever a change in the production, process, control 
equipment, personnel, or work practices may reasonably be expected to 
result in new or additional exposures at or above the action level, or 
when the employer has any reason to believe that new or additional 
exposures at or above the action level have occurred.
    (5) Methods of sample analysis. The employer shall ensure that all 
samples taken to satisfy the monitoring requirements of paragraph (d) 
of this section are evaluated by a laboratory that analyzes air samples 
for respirable crystalline silica in accordance with the procedures in 
Appendix A to this section.
    (6) Employee notification of assessment results. (i) Within 15 
working days after completing an exposure assessment in accordance with 
paragraph (d) of this section, the employer shall individually notify 
each affected employee in writing of the results of that assessment or 
post the results in an appropriate location accessible to all affected 
employees.
    (ii) Whenever an exposure assessment indicates that employee 
exposure is above the PEL, the employer shall describe in the written 
notification the corrective action being taken to reduce employee 
exposure to or below the PEL.
    (7) Observation of monitoring. (i) Where air monitoring is 
performed to comply with the requirements of this section, the employer 
shall provide affected employees or their designated representatives an 
opportunity to observe any monitoring of employee exposure to 
respirable crystalline silica.
    (ii) When observation of monitoring requires entry into an area 
where the use of protective clothing or equipment is required for any 
workplace hazard, the employer shall provide the observer with 
protective clothing and equipment at no cost and shall ensure that the 
observer uses such clothing and equipment.
    (e) Regulated areas--(1) Establishment. The employer shall 
establish a regulated area wherever an employee's exposure to airborne 
concentrations of respirable crystalline silica is, or can reasonably 
be expected to be, in excess of the PEL.
    (2) Demarcation. (i) The employer shall demarcate regulated areas 
from the rest of the workplace in a manner that minimizes the number of 
employees exposed to respirable crystalline silica within the regulated 
area.
    (ii) The employer shall post signs at all entrances to regulated 
areas that bear the legend specified in paragraph (j)(2) of this 
section.
    (3) Access. The employer shall limit access to regulated areas to:
    (A) Persons authorized by the employer and required by work duties 
to be present in the regulated area;
    (B) Any person entering such an area as a designated representative 
of employees for the purpose of exercising the right to observe 
monitoring procedures under paragraph (d) of this section; and
    (C) Any person authorized by the Occupational Safety and Health Act 
or regulations issued under it to be in a regulated area.
    (4) Provision of respirators. The employer shall provide each 
employee and the employee's designated representative entering a 
regulated area with an appropriate respirator in accordance with 
paragraph (g) of this section and shall require each employee and the 
employee's designated representative to use the respirator while in a 
regulated area.
    (f) Methods of compliance--(1) Engineering and work practice 
controls. The employer shall use engineering and work practice controls 
to reduce and maintain employee exposure to respirable crystalline 
silica to or below the PEL, unless the employer can demonstrate that 
such controls are not feasible. Wherever such feasible engineering and 
work practice controls are not sufficient to reduce employee exposure 
to or below the PEL, the employer shall nonetheless use them to reduce 
employee exposure to the lowest feasible level and shall supplement 
them with the use of respiratory protection that complies with the 
requirements of paragraph (g) of this section.
    (2) Written exposure control plan. (i) The employer shall establish 
and implement a written exposure control plan that contains at least 
the following elements:
    (A) A description of the tasks in the workplace that involve 
exposure to respirable crystalline silica;
    (B) A description of the engineering controls, work practices, and 
respiratory protection used to limit employee exposure to respirable 
crystalline silica for each task; and
    (C) A description of the housekeeping measures used to limit 
employee exposure to respirable crystalline silica.
    (ii) The employer shall review and evaluate the effectiveness of 
the written exposure control plan at least annually and update it as 
necessary.
    (iii) The employer shall make the written exposure control plan 
readily available for examination and copying, upon request, to each 
employee covered by this section, their designated representatives, the 
Assistant Secretary and the Director.
    (3) Abrasive blasting. In addition to the requirements of paragraph 
(f)(1) of this section, the employer shall comply

[[Page 16864]]

with other OSHA standards, when applicable, such as 29 CFR 1910.94 
(Ventilation), 29 CFR 1915.34 (Mechanical paint removers), and 29 CFR 
1915 Subpart I (Personal Protective Equipment), where abrasive blasting 
is conducted using crystalline silica-containing blasting agents, or 
where abrasive blasting is conducted on substrates that contain 
crystalline silica.
    (g) Respiratory protection--(1) General. Where respiratory 
protection is required by this section, the employer must provide each 
employee an appropriate respirator that complies with the requirements 
of this paragraph and 29 CFR 1910.134. Respiratory protection is 
required:
    (i) Where exposures exceed the PEL during periods necessary to 
install or implement feasible engineering and work practice controls;
    (ii) Where exposures exceed the PEL during tasks, such as certain 
maintenance and repair tasks, for which engineering and work practice 
controls are not feasible;
    (iii) During tasks for which an employer has implemented all 
feasible engineering and work practice controls and such controls are 
not sufficient to reduce exposures to or below the PEL; and
    (iv) During periods when the employee is in a regulated area.
    (2) Respiratory protection program. Where respirator use is 
required by this section, the employer shall institute a respiratory 
protection program in accordance with 29 CFR 1910.134.
    (h) Housekeeping. (1) The employer shall not allow dry sweeping or 
dry brushing where such activity could contribute to employee exposure 
to respirable crystalline silica unless wet sweeping, HEPA-filtered 
vacuuming or other methods that minimize the likelihood of exposure are 
not feasible.
    (2) The employer shall not allow compressed air to be used to clean 
clothing or surfaces where such activity could contribute to employee 
exposure to respirable crystalline silica unless:
    (i) The compressed air is used in conjunction with a ventilation 
system that effectively captures the dust cloud created by the 
compressed air; or
    (ii) No alternative method is feasible.
    (i) Medical surveillance--(1) General. (i) The employer shall make 
medical surveillance available at no cost to the employee, and at a 
reasonable time and place, for each employee who will be occupationally 
exposed to respirable crystalline silica at or above the action level 
for 30 or more days per year.
    (ii) The employer shall ensure that all medical examinations and 
procedures required by this section are performed by a PLHCP as defined 
in paragraph (b) of this section.
    (2) Initial examination. The employer shall make available an 
initial (baseline) medical examination within 30 days after initial 
assignment, unless the employee has received a medical examination that 
meets the requirements of this section within the last three years. The 
examination shall consist of:
    (i) A medical and work history, with emphasis on: Past, present, 
and anticipated exposure to respirable crystalline silica, dust, and 
other agents affecting the respiratory system; any history of 
respiratory system dysfunction, including signs and symptoms of 
respiratory disease (e.g., shortness of breath, cough, wheezing); 
history of tuberculosis; and smoking status and history;
    (ii) A physical examination with special emphasis on the 
respiratory system;
    (iii) A chest X-ray (a single posteroanterior radiographic 
projection or radiograph of the chest at full inspiration recorded on 
either film (no less than 14 x 17 inches and no more than 16 x 17 
inches) or digital radiography systems), interpreted and classified 
according to the International Labour Office (ILO) International 
Classification of Radiographs of Pneumoconioses by a NIOSH-certified B 
Reader;
    (iv) A pulmonary function test to include forced vital capacity 
(FVC) and forced expiratory volume in one second (FEV1) and 
FEV1/FVC ratio, administered by a spirometry technician with 
a current certificate from a NIOSH-approved spirometry course;
    (v) Testing for latent tuberculosis infection; and
    (vi) Any other tests deemed appropriate by the PLHCP.
    (3) Periodic examinations. The employer shall make available 
medical examinations that include the procedures described in paragraph 
(i)(2) of this section (except paragraph (i)(2)(v)) at least every 
three years, or more frequently if recommended by the PLHCP.
    (4) Information provided to the PLHCP. The employer shall ensure 
that the examining PLHCP has a copy of this standard, and shall provide 
the PLHCP with the following information:
    (i) A description of the employee's former, current, and 
anticipated duties as they relate to the employee's occupational 
exposure to respirable crystalline silica;
    (ii) The employee's former, current, and anticipated levels of 
occupational exposure to respirable crystalline silica;
    (iii) A description of any personal protective equipment used or to 
be used by the employee, including when and for how long the employee 
has used or will use that equipment; and
    (iv) Information from records of employment-related medical 
examinations previously provided to the employee and currently within 
the control of the employer.
    (5) PLHCP's written medical report for the employee. The employer 
shall ensure that the PLHCP explains to the employee the results of the 
medical examination and provides each employee with a written medical 
report within 30 days of each medical examination performed. The 
written report shall contain:
    (i) A statement indicating the results of the medical examination, 
including any medical condition(s) that would place the employee at 
increased risk of material impairment to health from exposure to 
respirable crystalline silica and any medical conditions that require 
further evaluation or treatment;
    (ii) Any recommended limitations on the employee's use of 
respirators;
    (iii) Any recommended limitations on the employee's exposure to 
respirable crystalline silica; and
    (iv) A statement that the employee should be examined by a 
specialist (pursuant to paragraph (i)(7) of this section) if the chest 
X-ray provided in accordance with this section is classified as 1/0 or 
higher by the B Reader, or if referral to a specialist is otherwise 
deemed appropriate by the PLHCP.
    (6) PLHCP's written medical opinion for the employer. (i) The 
employer shall obtain a written medical opinion from the PLHCP within 
30 days of the medical examination. The written opinion shall contain 
only the following:
    (A) The date of the examination;
    (B) A statement that the examination has met the requirements of 
this section; and
    (C) Any recommended limitations on the employee's use of 
respirators.
    (ii) If the employee provides written authorization, the written 
opinion shall also contain either or both of the following:
    (A) Any recommended limitations on the employee's exposure to 
respirable crystalline silica;
    (B) A statement that the employee should be examined by a 
specialist (pursuant to paragraph (i)(7) of this section) if the chest 
X-ray provided in accordance with this section is classified as 1/0 or 
higher by the B Reader, or if referral to a specialist is

[[Page 16865]]

otherwise deemed appropriate by the PLHCP.
    (iii) The employer shall ensure that each employee receives a copy 
of the written medical opinion described in paragraph (i)(6)(i) and 
(ii) of this section within 30 days of each medical examination 
performed.
    (7) Additional examinations. (i) If the PLHCP's written medical 
opinion indicates that an employee should be examined by a specialist, 
the employer shall make available a medical examination by a specialist 
within 30 days after receiving the PLHCP's written opinion.
    (ii) The employer shall ensure that the examining specialist is 
provided with all of the information that the employer is obligated to 
provide to the PLHCP in accordance with paragraph (i)(4) of this 
section.
    (iii) The employer shall ensure that the specialist explains to the 
employee the results of the medical examination and provides each 
employee with a written medical report within 30 days of the 
examination. The written report shall meet the requirements of 
paragraph (i)(5) (except paragraph (i)(5)(iv)) of this section.
    (iv) The employer shall obtain a written opinion from the 
specialist within 30 days of the medical examination. The written 
opinion shall meet the requirements of paragraph (i)(6) (except 
paragraph (i)(6)(i)(B) and (i)(6)(ii)(B)) of this section.
    (j) Communication of respirable crystalline silica hazards to 
employees--(1) Hazard communication. The employer shall include 
respirable crystalline silica in the program established to comply with 
the hazard communication standard (HCS) (29 CFR 1910.1200). The 
employer shall ensure that each employee has access to labels on 
containers of crystalline silica and safety data sheets, and is trained 
in accordance with the provisions of HCS and paragraph (j)(3) of this 
section. The employer shall ensure that at least the following hazards 
are addressed: Cancer, lung effects, immune system effects, and kidney 
effects.
    (2) Signs. The employer shall post signs at all entrances to 
regulated areas that bear the following legend:

DANGER
RESPIRABLE CRYSTALLINE SILICA
MAY CAUSE CANCER
CAUSES DAMAGE TO LUNGS
WEAR RESPIRATORY PROTECTION IN THIS AREA
AUTHORIZED PERSONNEL ONLY

    (3) Employee information and training. (i) The employer shall 
ensure that each employee covered by this section can demonstrate 
knowledge and understanding of at least the following:
    (A) The health hazards associated with exposure to respirable 
crystalline silica;
    (B) Specific tasks in the workplace that could result in exposure 
to respirable crystalline silica;
    (C) Specific measures the employer has implemented to protect 
employees from exposure to respirable crystalline silica, including 
engineering controls, work practices, and respirators to be used;
    (D) The contents of this section; and
    (E) The purpose and a description of the medical surveillance 
program required by paragraph (i) of this section.
    (ii) The employer shall make a copy of this section readily 
available without cost to each employee covered by this section.
    (k) Recordkeeping--(1) Air monitoring data. (i) The employer shall 
make and maintain an accurate record of all exposure measurements taken 
to assess employee exposure to respirable crystalline silica, as 
prescribed in paragraph (d) of this section.
    (ii) This record shall include at least the following information:
    (A) The date of measurement for each sample taken;
    (B) The task monitored;
    (C) Sampling and analytical methods used;
    (D) Number, duration, and results of samples taken;
    (E) Identity of the laboratory that performed the analysis;
    (F) Type of personal protective equipment, such as respirators, 
worn by the employees monitored; and
    (G) Name, social security number, and job classification of all 
employees represented by the monitoring, indicating which employees 
were actually monitored.
    (iii) The employer shall ensure that exposure records are 
maintained and made available in accordance with 29 CFR 1910.1020.
    (2) Objective data. (i) The employer shall make and maintain an 
accurate record of all objective data relied upon to comply with the 
requirements of this section.
    (ii) This record shall include at least the following information:
    (A) The crystalline silica-containing material in question;
    (B) The source of the objective data;
    (C) The testing protocol and results of testing;
    (D) A description of the process, task, or activity on which the 
objective data were based; and
    (E) Other data relevant to the process, task, activity, material, 
or exposures on which the objective data were based.
    (iii) The employer shall ensure that objective data are maintained 
and made available in accordance with 29 CFR 1910.1020.
    (3) Medical surveillance. (i) The employer shall make and maintain 
an accurate record for each employee covered by medical surveillance 
under paragraph (i) of this section.
    (ii) The record shall include the following information about the 
employee:
    (A) Name and social security number;
    (B) A copy of the PLHCPs' and specialists' written medical 
opinions; and
    (C) A copy of the information provided to the PLHCPs and 
specialists.
    (iii) The employer shall ensure that medical records are maintained 
and made available in accordance with 29 CFR 1910.1020.
    (l) Dates. (1) This section is effective June 23, 2016.
    (2) Except as provided for in paragraphs (l)(3) and (4) of this 
section, all obligations of this section commence June 23, 2018.
    (3) For hydraulic fracturing operations in the oil and gas 
industry:
    (i) All obligations of this section, except obligations for medical 
surveillance in paragraph (i)(1)(i) and engineering controls in 
paragraph (f)(1) of this section, commence June 23, 2018;
    (ii) Obligations for engineering controls in paragraph (f)(1) of 
this section commence June 23, 2021; and
    (iii) Obligations for medical surveillance in paragraph (i)(1)(i) 
commence in accordance with paragraph (l)(4) of this section.
    (4) The medical surveillance obligations in paragraph (i)(1)(i) 
commence on June 23, 2018, for employees who will be occupationally 
exposed to respirable crystalline silica above the PEL for 30 or more 
days per year. Those obligations commence June 23, 2020, for employees 
who will be occupationally exposed to respirable crystalline silica at 
or above the action level for 30 or more days per year.

Appendix A to Sec.  1910.1053--Methods of Sample Analysis

    This appendix specifies the procedures for analyzing air samples 
for respirable crystalline silica, as well as the quality control 
procedures that employers must ensure that laboratories use when 
performing an analysis required under 29 CFR 1910.1053 (d)(5). 
Employers must ensure that such a laboratory:
    1. Evaluates all samples using the procedures specified in one 
of the following analytical methods: OSHA ID-142; NMAM 7500; NMAM 
7602; NMAM 7603; MSHA P-2; or MSHA P-7;

[[Page 16866]]

    2. Is accredited to ANS/ISO/IEC Standard 17025:2005 with respect 
to crystalline silica analyses by a body that is compliant with ISO/
IEC Standard 17011:2004 for implementation of quality assessment 
programs;
    3. Uses the most current National Institute of Standards and 
Technology (NIST) or NIST traceable standards for instrument 
calibration or instrument calibration verification;
    4. Implements an internal quality control (QC) program that 
evaluates analytical uncertainty and provides employers with 
estimates of sampling and analytical error;
    5. Characterizes the sample material by identifying polymorphs 
of respirable crystalline silica present, identifies the presence of 
any interfering compounds that might affect the analysis, and makes 
any corrections necessary in order to obtain accurate sample 
analysis; and
    6. Analyzes quantitatively for crystalline silica only after 
confirming that the sample matrix is free of uncorrectable 
analytical interferences, corrects for analytical interferences, and 
uses a method that meets the following performance specifications:
    6.1 Each day that samples are analyzed, performs instrument 
calibration checks with standards that bracket the sample 
concentrations;
    6.2 Uses five or more calibration standard levels to prepare 
calibration curves and ensures that standards are distributed 
through the calibration range in a manner that accurately reflects 
the underlying calibration curve; and
    6.3 Optimizes methods and instruments to obtain a quantitative 
limit of detection that represents a value no higher than 25 percent 
of the PEL based on sample air volume.

Appendix B to Sec.  1910.1053--Medical Surveillance Guidelines

Introduction

    The purpose of this Appendix is to provide medical information 
and recommendations to aid physicians and other licensed health care 
professionals (PLHCPs) regarding compliance with the medical 
surveillance provisions of the respirable crystalline silica 
standard (29 CFR 1910.1053). Appendix B is for informational and 
guidance purposes only and none of the statements in Appendix B 
should be construed as imposing a mandatory requirement on employers 
that is not otherwise imposed by the standard.
    Medical screening and surveillance allow for early 
identification of exposure-related health effects in individual 
employee and groups of employees, so that actions can be taken to 
both avoid further exposure and prevent or address adverse health 
outcomes. Silica-related diseases can be fatal, encompass a variety 
of target organs, and may have public health consequences when 
considering the increased risk of a latent tuberculosis (TB) 
infection becoming active. Thus, medical surveillance of silica-
exposed employees requires that PLHCPs have a thorough knowledge of 
silica-related health effects.
    This Appendix is divided into seven sections. Section 1 reviews 
silica-related diseases, medical responses, and public health 
responses. Section 2 outlines the components of the medical 
surveillance program for employees exposed to silica. Section 3 
describes the roles and responsibilities of the PLHCP implementing 
the program and of other medical specialists and public health 
professionals. Section 4 provides a discussion of considerations, 
including confidentiality. Section 5 provides a list of additional 
resources and Section 6 lists references. Section 7 provides sample 
forms for the written medical report for the employee, the written 
medical opinion for the employer and the written authorization.

1. Recognition of Silica-Related Diseases

    1.1. Overview. The term ``silica'' refers specifically to the 
compound silicon dioxide (SiO2). Silica is a major component of 
sand, rock, and mineral ores. Exposure to fine (respirable size) 
particles of crystalline forms of silica is associated with adverse 
health effects, such as silicosis, lung cancer, chronic obstructive 
pulmonary disease (COPD), and activation of latent TB infections. 
Exposure to respirable crystalline silica can occur in industry 
settings such as foundries, abrasive blasting operations, paint 
manufacturing, glass and concrete product manufacturing, brick 
making, china and pottery manufacturing, manufacturing of plumbing 
fixtures, and many construction activities including highway repair, 
masonry, concrete work, rock drilling, and tuck-pointing. New uses 
of silica continue to emerge. These include countertop 
manufacturing, finishing, and installation (Kramer et al. 2012; OSHA 
2015) and hydraulic fracturing in the oil and gas industry (OSHA 
2012).
    Silicosis is an irreversible, often disabling, and sometimes 
fatal fibrotic lung disease. Progression of silicosis can occur 
despite removal from further exposure. Diagnosis of silicosis 
requires a history of exposure to silica and radiologic findings 
characteristic of silica exposure. Three different presentations of 
silicosis (chronic, accelerated, and acute) have been defined. 
Accelerated and acute silicosis are much less common than chronic 
silicosis. However, it is critical to recognize all cases of 
accelerated and acute silicosis because these are life-threatening 
illnesses and because they are caused by substantial overexposures 
to respirable crystalline silica. Although any case of silicosis 
indicates a breakdown in prevention, a case of acute or accelerated 
silicosis implies current high exposure and a very marked breakdown 
in prevention.
    In addition to silicosis, employees exposed to respirable 
crystalline silica, especially those with accelerated or acute 
silicosis, are at increased risks of contracting active TB and other 
infections (ATS 1997; Rees and Murray 2007). Exposure to respirable 
crystalline silica also increases an employee's risk of developing 
lung cancer, and the higher the cumulative exposure, the higher the 
risk (Steenland et al. 2001; Steenland and Ward 2014). Symptoms for 
these diseases and other respirable crystalline silica-related 
diseases are discussed below.
    1.2. Chronic Silicosis. Chronic silicosis is the most common 
presentation of silicosis and usually occurs after at least 10 years 
of exposure to respirable crystalline silica. The clinical 
presentation of chronic silicosis is:
    1.2.1. Symptoms--shortness of breath and cough, although 
employees may not notice any symptoms early in the disease. 
Constitutional symptoms, such as fever, loss of appetite and 
fatigue, may indicate other diseases associated with silica 
exposure, such as TB infection or lung cancer. Employees with these 
symptoms should immediately receive further evaluation and 
treatment.
    1.2.2. Physical Examination--may be normal or disclose dry rales 
or rhonchi on lung auscultation.
    1.2.3. Spirometry--may be normal or may show only a mild 
restrictive or obstructive pattern.
    1.2.4. Chest X-ray--classic findings are small, rounded 
opacities in the upper lung fields bilaterally. However, small 
irregular opacities and opacities in other lung areas can also 
occur. Rarely, ``eggshell calcifications'' in the hilar and 
mediastinal lymph nodes are seen.
    1.2.5. Clinical Course--chronic silicosis in most cases is a 
slowly progressive disease. Under the respirable crystalline silica 
standard, the PLHCP is to recommend that employees with a 1/0 
category X-ray be referred to an American Board Certified Specialist 
in Pulmonary Disease or Occupational Medicine. The PLHCP and/or 
Specialist should counsel employees regarding work practices and 
personal habits that could affect employees' respiratory health.
    1.3. Accelerated Silicosis. Accelerated silicosis generally 
occurs within 5-10 years of exposure and results from high levels of 
exposure to respirable crystalline silica. The clinical presentation 
of accelerated silicosis is:
    1.3.1. Symptoms--shortness of breath, cough, and sometimes 
sputum production. Employees with exposure to respirable crystalline 
silica, and especially those with accelerated silicosis, are at high 
risk for activation of TB infections, atypical mycobacterial 
infections, and fungal superinfections. Constitutional symptoms, 
such as fever, weight loss, hemoptysis (coughing up blood), and 
fatigue may herald one of these infections or the onset of lung 
cancer.
    1.3.2. Physical Examination--rales, rhonchi, or other abnormal 
lung findings in relation to illnesses present. Clubbing of the 
digits, signs of heart failure, and cor pulmonale may be present in 
severe lung disease.
    1.3.3. Spirometry--restrictive or mixed restrictive/obstructive 
pattern.
    1.3.4. Chest X-ray--small rounded and/or irregular opacities 
bilaterally. Large opacities and lung abscesses may indicate 
infections, lung cancer, or progression to complicated silicosis, 
also termed progressive massive fibrosis.
    1.3.5. Clinical Course--accelerated silicosis has a rapid, 
severe course. Under the respirable crystalline silica standard, the 
PLHCP can recommend referral to a Board Certified Specialist in 
either Pulmonary Disease or Occupational Medicine, as deemed 
appropriate, and referral to a Specialist is recommended whenever 
the diagnosis of accelerated silicosis is being considered.

[[Page 16867]]

    1.4. Acute Silicosis. Acute silicosis is a rare disease caused 
by inhalation of extremely high levels of respirable crystalline 
silica particles. The pathology is similar to alveolar proteinosis 
with lipoproteinaceous material accumulating in the alveoli. Acute 
silicosis develops rapidly, often, within a few months to less than 
2 years of exposure, and is almost always fatal. The clinical 
presentation of acute silicosis is as follows:
    1.4.1. Symptoms--sudden, progressive, and severe shortness of 
breath. Constitutional symptoms are frequently present and include 
fever, weight loss, fatigue, productive cough, hemoptysis (coughing 
up blood), and pleuritic chest pain.
    1.4.2. Physical Examination--dyspnea at rest, cyanosis, 
decreased breath sounds, inspiratory rales, clubbing of the digits, 
and fever.
    1.4.3. Spirometry--restrictive or mixed restrictive/obstructive 
pattern.
    1.4.4. Chest X-ray--diffuse haziness of the lungs bilaterally 
early in the disease. As the disease progresses, the ``ground 
glass'' appearance of interstitial fibrosis will appear.
    1.4.5. Clinical Course--employees with acute silicosis are at 
especially high risk of TB activation, nontuberculous mycobacterial 
infections, and fungal superinfections. Acute silicosis is 
immediately life-threatening. The employee should be urgently 
referred to a Board Certified Specialist in Pulmonary Disease or 
Occupational Medicine for evaluation and treatment. Although any 
case of silicosis indicates a breakdown in prevention, a case of 
acute or accelerated silicosis implies a profoundly high level of 
silica exposure and may mean that other employees are currently 
exposed to dangerous levels of silica.
    1.5. COPD. COPD, including chronic bronchitis and emphysema, has 
been documented in silica-exposed employees, including those who do 
not develop silicosis. Periodic spirometry tests are performed to 
evaluate each employee for progressive changes consistent with the 
development of COPD. In addition to evaluating spirometry results of 
individual employees over time, PLHCPs may want to be aware of 
general trends in spirometry results for groups of employees from 
the same workplace to identify possible problems that might exist at 
that workplace. (See Section 2 of this Appendix on Medical 
Surveillance for further discussion.) Heart disease may develop 
secondary to lung diseases such as COPD. A recent study by Liu et 
al. 2014 noted a significant exposure-response trend between 
cumulative silica exposure and heart disease deaths, primarily due 
to pulmonary heart disease, such as cor pulmonale.
    1.6. Renal and Immune System. Silica exposure has been 
associated with several types of kidney disease, including 
glomerulonephritis, nephrotic syndrome, and end stage renal disease 
requiring dialysis. Silica exposure has also been associated with 
other autoimmune conditions, including progressive systemic 
sclerosis, systemic lupus erythematosus, and rheumatoid arthritis. 
Studies note an association between employees with silicosis and 
serologic markers for autoimmune diseases, including antinuclear 
antibodies, rheumatoid factor, and immune complexes (Jalloul and 
Banks 2007; Shtraichman et al. 2015).
    1.7. TB and Other Infections. Silica-exposed employees with 
latent TB are 3 to 30 times more likely to develop active pulmonary 
TB infection (ATS 1997; Rees and Murray 2007). Although respirable 
crystalline silica exposure does not cause TB infection, individuals 
with latent TB infection are at increased risk for activation of 
disease if they have higher levels of respirable crystalline silica 
exposure, greater profusion of radiographic abnormalities, or a 
diagnosis of silicosis. Demographic characteristics, such as 
immigration from some countries, are associated with increased rates 
of latent TB infection. PLHCPs can review the latest Centers for 
Disease Control and Prevention (CDC) information on TB incidence 
rates and high risk populations online (See Section 5 of this 
Appendix). Additionally, silica-exposed employees are at increased 
risk for contracting nontuberculous mycobacterial infections, 
including Mycobacterium avium-intracellulare and Mycobacterium 
kansaii.
    1.8. Lung Cancer. The National Toxicology Program has listed 
respirable crystalline silica as a known human carcinogen since 2000 
(NTP 2014). The International Agency for Research on Cancer (2012) 
has also classified silica as Group 1 (carcinogenic to humans). 
Several studies have indicated that the risk of lung cancer from 
exposure to respirable crystalline silica and smoking is greater 
than additive (Brown 2009; Liu et al. 2013). Employees should be 
counseled on smoking cessation.

2. Medical Surveillance

    PLHCPs who manage silica medical surveillance programs should 
have a thorough understanding of the many silica-related diseases 
and health effects outlined in Section 1 of this Appendix. At each 
clinical encounter, the PLHCP should consider silica-related health 
outcomes, with particular vigilance for acute and accelerated 
silicosis. In this Section, the required components of medical 
surveillance under the respirable crystalline silica standard are 
reviewed, along with additional guidance and recommendations for 
PLHCPs performing medical surveillance examinations for silica-
exposed employees.

2.1. History

    2.1.1. The respirable crystalline silica standard requires the 
following: A medical and work history, with emphasis on: Past, 
present, and anticipated exposure to respirable crystalline silica, 
dust, and other agents affecting the respiratory system; any history 
of respiratory system dysfunction, including signs and symptoms of 
respiratory disease (e.g., shortness of breath, cough, wheezing); 
history of TB; and smoking status and history.
    2.1.2. Further, the employer must provide the PLHCP with the 
following information:
    2.1.2.1. A description of the employee's former, current, and 
anticipated duties as they relate to the employee's occupational 
exposure to respirable crystalline silica;
    2.1.2.2. The employee's former, current, and anticipated levels 
of occupational exposure to respirable crystalline silica;
    2.1.2.3. A description of any personal protective equipment used 
or to be used by the employee, including when and for how long the 
employee has used or will use that equipment; and
    2.1.2.4. Information from records of employment-related medical 
examinations previously provided to the employee and currently 
within the control of the employer.
    2.1.3. Additional guidance and recommendations: A history is 
particularly important both in the initial evaluation and in 
periodic examinations. Information on past and current medical 
conditions (particularly a history of kidney disease, cardiac 
disease, connective tissue disease, and other immune diseases), 
medications, hospitalizations and surgeries may uncover health 
risks, such as immune suppression, that could put an employee at 
increased health risk from exposure to silica. This information is 
important when counseling the employee on risks and safe work 
practices related to silica exposure.

2.2. Physical Examination

    2.2.1. The respirable crystalline silica standard requires the 
following: A physical examination, with special emphasis on the 
respiratory system. The physical examination must be performed at 
the initial examination and every three years thereafter.
    2.2.2. Additional guidance and recommendations: Elements of the 
physical examination that can assist the PHLCP include: An 
examination of the cardiac system, an extremity examination (for 
clubbing, cyanosis, edema, or joint abnormalities), and an 
examination of other pertinent organ systems identified during the 
history.

2.3. TB Testing

    2.3.1. The respirable crystalline silica standard requires the 
following: Baseline testing for TB on initial examination.
    2.3.2. Additional guidance and recommendations:
    2.3.2.1. Current CDC guidelines (See Section 5 of this Appendix) 
should be followed for the application and interpretation of 
Tuberculin skin tests (TST). The interpretation and documentation of 
TST reactions should be performed within 48 to 72 hours of 
administration by trained PLHCPs.
    2.3.2.2. PLHCPs may use alternative TB tests, such as 
interferon-[gamma] release assays (IGRAs), if sensitivity and 
specificity are comparable to TST (Mazurek et al. 2010; Slater et 
al. 2013). PLHCPs can consult the current CDC guidelines for 
acceptable tests for latent TB infection.
    2.3.2.3. The silica standard allows the PLHCP to order 
additional tests or test at a greater frequency than required by the 
standard, if deemed appropriate. Therefore, PLHCPs might perform 
periodic (e.g., annual) TB testing as appropriate, based on 
employees' risk factors. For example, according to the American 
Thoracic Society (ATS), the diagnosis of silicosis or exposure to 
silica for 25 years or more are indications for annual TB testing 
(ATS 1997). PLHCPs

[[Page 16868]]

should consult the current CDC guidance on risk factors for TB (See 
Section 5 of this Appendix).
    2.3.2.4. Employees with positive TB tests and those with 
indeterminate test results should be referred to the appropriate 
agency or specialist, depending on the test results and clinical 
picture. Agencies, such as local public health departments, or 
specialists, such as a pulmonary or infectious disease specialist, 
may be the appropriate referral. Active TB is a nationally 
notifiable disease. PLHCPs should be aware of the reporting 
requirements for their region. All States have TB Control Offices 
that can be contacted for further information. (See Section 5 of 
this Appendix for links to CDC's TB resources and State TB Control 
Offices.)
    2.3.2.5. The following public health principles are key to TB 
control in the U.S. (ATS-CDC-IDSA 2005):
    (1) Prompt detection and reporting of persons who have 
contracted active TB;
    (2) Prevention of TB spread to close contacts of active TB 
cases;
    (3) Prevention of active TB in people with latent TB through 
targeted testing and treatment; and
    (4) Identification of settings at high risk for TB transmission 
so that appropriate infection-control measures can be implemented.

2.4. Pulmonary Function Testing

    2.4.1. The respirable crystalline silica standard requires the 
following: Pulmonary function testing must be performed on the 
initial examination and every three years thereafter. The required 
pulmonary function test is spirometry and must include forced vital 
capacity (FVC), forced expiratory volume in one second 
(FEV1), and FEV1/FVC ratio. Testing must be 
administered by a spirometry technician with a current certificate 
from a National Institute for Occupational Health and Safety 
(NIOSH)-approved spirometry course.
    2.4.2. Additional guidance and recommendations: Spirometry 
provides information about individual respiratory status and can be 
used to track an employee's respiratory status over time or as a 
surveillance tool to follow individual and group respiratory 
function. For quality results, the ATS and the American College of 
Occupational and Environmental Medicine (ACOEM) recommend use of the 
third National Health and Nutrition Examination Survey (NHANES III) 
values, and ATS publishes recommendations for spirometry equipment 
(Miller et al. 2005; Townsend 2011; Redlich et al. 2014). OSHA's 
publication, Spirometry Testing in Occupational Health Programs: 
Best Practices for Healthcare Professionals, provides helpful 
guidance (See Section 5 of this Appendix). Abnormal spirometry 
results may warrant further clinical evaluation and possible 
recommendations for limitations on the employee's exposure to 
respirable crystalline silica.

2.5. Chest X-ray

    2.5.1. The respirable crystalline silica standard requires the 
following: A single posteroanterior (PA) radiographic projection or 
radiograph of the chest at full inspiration recorded on either film 
(no less than 14 x 17 inches and no more than 16 x 17 inches) or 
digital radiography systems. A chest X-ray must be performed on the 
initial examination and every three years thereafter. The chest X-
ray must be interpreted and classified according to the 
International Labour Office (ILO) International Classification of 
Radiographs of Pneumoconioses by a NIOSH-certified B Reader.
    Chest radiography is necessary to diagnose silicosis, monitor 
the progression of silicosis, and identify associated conditions 
such as TB. If the B reading indicates small opacities in a 
profusion of 1/0 or higher, the employee is to receive a 
recommendation for referral to a Board Certified Specialist in 
Pulmonary Disease or Occupational Medicine.
    2.5.2. Additional guidance and recommendations: Medical imaging 
has largely transitioned from conventional film-based radiography to 
digital radiography systems. The ILO Guidelines for the 
Classification of Pneumoconioses has historically provided film-
based chest radiography as a referent standard for comparison to 
individual exams. However, in 2011, the ILO revised the guidelines 
to include a digital set of referent standards that were derived 
from the prior film-based standards. To assist in assuring that 
digitally-acquired radiographs are at least as safe and effective as 
film radiographs, NIOSH has prepared guidelines, based upon accepted 
contemporary professional recommendations (See Section 5 of this 
Appendix). Current research from Laney et al. 2011 and Halldin et 
al. 2014 validate the use of the ILO digital referent images. Both 
studies conclude that the results of pneumoconiosis classification 
using digital references are comparable to film-based ILO 
classifications. Current ILO guidance on radiography for 
pneumoconioses and B-reading should be reviewed by the PLHCP 
periodically, as needed, on the ILO or NIOSH Web sites (See Section 
5 of this Appendix).
    2.6. Other Testing. Under the respirable crystalline silica 
standards, the PLHCP has the option of ordering additional testing 
he or she deems appropriate. Additional tests can be ordered on a 
case-by-case basis depending on individual signs or symptoms and 
clinical judgment. For example, if an employee reports a history of 
abnormal kidney function tests, the PLHCP may want to order a 
baseline renal function tests (e.g., serum creatinine and 
urinalysis). As indicated above, the PLHCP may order annual TB 
testing for silica-exposed employees who are at high risk of 
developing active TB infections. Additional tests that PLHCPs may 
order based on findings of medical examinations include, but is not 
limited to, chest computerized tomography (CT) scan for lung cancer 
or COPD, testing for immunologic diseases, and cardiac testing for 
pulmonary-related heart disease, such as cor pulmonale.

3. Roles and Responsibilities

    3.1. PLHCP. The PLHCP designation refers to ``an individual 
whose legally permitted scope of practice (i.e., license, 
registration, or certification) allows him or her to independently 
provide or be delegated the responsibility to provide some or all of 
the particular health care services required'' by the respirable 
crystalline silica standard. The legally permitted scope of practice 
for the PLHCP is determined by each State. PLHCPs who perform 
clinical services for a silica medical surveillance program should 
have a thorough knowledge of respirable crystalline silica-related 
diseases and symptoms. Suspected cases of silicosis, advanced COPD, 
or other respiratory conditions causing impairment should be 
promptly referred to a Board Certified Specialist in Pulmonary 
Disease or Occupational Medicine.
    Once the medical surveillance examination is completed, the 
employer must ensure that the PLHCP explains to the employee the 
results of the medical examination and provides the employee with a 
written medical report within 30 days of the examination. The 
written medical report must contain a statement indicating the 
results of the medical examination, including any medical 
condition(s) that would place the employee at increased risk of 
material impairment to health from exposure to respirable 
crystalline silica and any medical conditions that require further 
evaluation or treatment. In addition, the PLHCP's written medical 
report must include any recommended limitations on the employee's 
use of respirators, any recommended limitations on the employee's 
exposure to respirable crystalline silica, and a statement that the 
employee should be examined by a Board Certified Specialist in 
Pulmonary Disease or Occupational medicine if the chest X-ray is 
classified as 1/0 or higher by the B Reader, or if referral to a 
Specialist is otherwise deemed appropriate by the PLHCP.
    The PLHCP should discuss all findings and test results and any 
recommendations regarding the employee's health, worksite safety and 
health practices, and medical referrals for further evaluation, if 
indicated. In addition, it is suggested that the PLHCP offer to 
provide the employee with a complete copy of their examination and 
test results, as some employees may want this information for their 
own records or to provide to their personal physician or a future 
PLHCP. Employees are entitled to access their medical records.
    Under the respirable crystalline silica standard, the employer 
must ensure that the PLHCP provides the employer with a written 
medical opinion within 30 days of the employee examination, and that 
the employee also gets a copy of the written medical opinion for the 
employer within 30 days. The PLHCP may choose to directly provide 
the employee a copy of the written medical opinion. This can be 
particularly helpful to employees, such as construction employees, 
who may change employers frequently. The written medical opinion can 
be used by the employee as proof of up-to-date medical surveillance. 
The following lists the elements of the written medical report for 
the employee and written medical opinion for the employer. (Sample 
forms for the written medical report for the employee, the written 
medical opinion for the employer, and the written authorization are 
provided in Section 7 of this Appendix.)

[[Page 16869]]

    3.1.1. The written medical report for the employee must include 
the following information:
    3.1.1.1. A statement indicating the results of the medical 
examination, including any medical condition(s) that would place the 
employee at increased risk of material impairment to health from 
exposure to respirable crystalline silica and any medical conditions 
that require further evaluation or treatment;
    3.1.1.2. Any recommended limitations upon the employee's use of 
a respirator;
    3.1.1.3. Any recommended limitations on the employee's exposure 
to respirable crystalline silica; and
    3.1.1.4. A statement that the employee should be examined by a 
Board Certified Specialist in Pulmonary Disease or Occupational 
Medicine, where the standard requires or where the PLHCP has 
determined such a referral is necessary. The standard requires 
referral to a Board Certified Specialist in Pulmonary Disease or 
Occupational Medicine for a chest X-ray B reading indicating small 
opacities in a profusion of 1/0 or higher, or if the PHLCP 
determines that referral to a Specialist is necessary for other 
silica-related findings.
    3.1.2. The PLHCP's written medical opinion for the employer must 
include only the following information:
    3.1.2.1. The date of the examination;
    3.1.2.2. A statement that the examination has met the 
requirements of this section; and
    3.1.2.3. Any recommended limitations on the employee's use of 
respirators.
    3.1.2.4. If the employee provides the PLHCP with written 
authorization, the written opinion for the employer shall also 
contain either or both of the following:
    (1) Any recommended limitations on the employee's exposure to 
respirable crystalline silica; and
    (2) A statement that the employee should be examined by a Board 
Certified Specialist in Pulmonary Disease or Occupational Medicine 
if the chest X-ray provided in accordance with this section is 
classified as 1/0 or higher by the B Reader, or if referral to a 
Specialist is otherwise deemed appropriate.
    3.1.2.5. In addition to the above referral for abnormal chest X-
ray, the PLHCP may refer an employee to a Board Certified Specialist 
in Pulmonary Disease or Occupational Medicine for other findings of 
concern during the medical surveillance examination if these 
findings are potentially related to silica exposure.
    3.1.2.6. Although the respirable crystalline silica standard 
requires the employer to ensure that the PLHCP explains the results 
of the medical examination to the employee, the standard does not 
mandate how this should be done. The written medical opinion for the 
employer could contain a statement that the PLHCP has explained the 
results of the medical examination to the employee.
    3.2. Medical Specialists. The silica standard requires that all 
employees with chest X-ray B readings of 1/0 or higher be referred 
to a Board Certified Specialist in Pulmonary Disease or Occupational 
Medicine. If the employee has given written authorization for the 
employer to be informed, then the employer shall make available a 
medical examination by a Specialist within 30 days after receiving 
the PLHCP's written medical opinion.
    3.2.1. The employer must provide the following information to 
the Board Certified Specialist in Pulmonary Disease or Occupational 
Medicine:
    3.2.1.1. A description of the employee's former, current, and 
anticipated duties as they relate to the employee's occupational 
exposure to respirable crystalline silica;
    3.2.1.2. The employee's former, current, and anticipated levels 
of occupational exposure to respirable crystalline silica;
    3.2.1.3. A description of any personal protective equipment used 
or to be used by the employee, including when and for how long the 
employee has used or will use that equipment; and
    3.2.1.4. Information from records of employment-related medical 
examinations previously provided to the employee and currently 
within the control of the employer.
    3.2.2. The PLHCP should make certain that, with written 
authorization from the employee, the Board Certified Specialist in 
Pulmonary Disease or Occupational Medicine has any other pertinent 
medical and occupational information necessary for the specialist's 
evaluation of the employee's condition.
    3.2.3. Once the Board Certified Specialist in Pulmonary Disease 
or Occupational Medicine has evaluated the employee, the employer 
must ensure that the Specialist explains to the employee the results 
of the medical examination and provides the employee with a written 
medical report within 30 days of the examination. The employer must 
also ensure that the Specialist provides the employer with a written 
medical opinion within 30 days of the employee examination. (Sample 
forms for the written medical report for the employee, the written 
medical opinion for the employer and the written authorization are 
provided in Section 7 of this Appendix.)
    3.2.4. The Specialist's written medical report for the employee 
must include the following information:
    3.2.4.1. A statement indicating the results of the medical 
examination, including any medical condition(s) that would place the 
employee at increased risk of material impairment to health from 
exposure to respirable crystalline silica and any medical conditions 
that require further evaluation or treatment;
    3.2.4.2. Any recommended limitations upon the employee's use of 
a respirator; and
    3.2.4.3. Any recommended limitations on the employee's exposure 
to respirable crystalline silica.
    3.2.5. The Specialist's written medical opinion for the employer 
must include the following information:
    3.2.5.1. The date of the examination; and
    3.2.5.2. Any recommended limitations on the employee's use of 
respirators.
    3.2.5.3. If the employee provides the Board Certified Specialist 
in Pulmonary Disease or Occupational Medicine with written 
authorization, the written medical opinion for the employer shall 
also contain any recommended limitations on the employee's exposure 
to respirable crystalline silica.
    3.2.5.4. Although the respirable crystalline silica standard 
requires the employer to ensure that the Board Certified Specialist 
in Pulmonary Disease or Occupational Medicine explains the results 
of the medical examination to the employee, the standard does not 
mandate how this should be done. The written medical opinion for the 
employer could contain a statement that the Specialist has explained 
the results of the medical examination to the employee.
    3.2.6. After evaluating the employee, the Board Certified 
Specialist in Pulmonary Disease or Occupational Medicine should 
provide feedback to the PLHCP as appropriate, depending on the 
reason for the referral. OSHA believes that because the PLHCP has 
the primary relationship with the employer and employee, the 
Specialist may want to communicate his or her findings to the PLHCP 
and have the PLHCP simply update the original medical report for the 
employee and medical opinion for the employer. This is permitted 
under the standard, so long as all requirements and time deadlines 
are met.
    3.3. Public Health Professionals. PLHCPs might refer employees 
or consult with public health professionals as a result of silica 
medical surveillance. For instance, if individual cases of active TB 
are identified, public health professionals from state or local 
health departments may assist in diagnosis and treatment of 
individual cases and may evaluate other potentially affected 
persons, including coworkers. Because silica-exposed employees are 
at increased risk of progression from latent to active TB, treatment 
of latent infection is recommended. The diagnosis of active TB, 
acute or accelerated silicosis, or other silica-related diseases and 
infections should serve as sentinel events suggesting high levels of 
exposure to silica and may require consultation with the appropriate 
public health agencies to investigate potentially similarly exposed 
coworkers to assess for disease clusters. These agencies include 
local or state health departments or OSHA. In addition, NIOSH can 
provide assistance upon request through their Health Hazard 
Evaluation program. (See Section 5 of this Appendix)

4. Confidentiality and Other Considerations

    The information that is provided from the PLHCP to the employee 
and employer under the medical surveillance section of OSHA's 
respirable crystalline silica standard differs from that of medical 
surveillance requirements in previous OSHA standards. The standard 
requires two separate written communications, a written medical 
report for the employee and a written medical opinion for the 
employer. The confidentiality requirements for the written medical 
opinion are more stringent than in past standards. For example, the 
information the PLHCP can (and must) include in his or her written 
medical opinion for the employer is limited to: The date of the 
examination, a statement that the examination has met the 
requirements of this section, and any recommended limitations on the 
employee's use of respirators. If the employee provides written 
authorization for the disclosure of

[[Page 16870]]

any limitations on the employee's exposure to respirable crystalline 
silica, then the PLHCP can (and must) include that information in 
the written medical opinion for the employer as well. Likewise, with 
the employee's written authorization, the PLHCP can (and must) 
disclose the PLHCP's referral recommendation (if any) as part of the 
written medical opinion for the employer. However, the opinion to 
the employer must not include information regarding recommended 
limitations on the employee's exposure to respirable crystalline 
silica or any referral recommendations without the employee's 
written authorization.
    The standard also places limitations on the information that the 
Board Certified Specialist in Pulmonary Disease or Occupational 
Medicine can provide to the employer without the employee's written 
authorization. The Specialist's written medical opinion for the 
employer, like the PLHCP's opinion, is limited to (and must 
contain): The date of the examination and any recommended 
limitations on the employee's use of respirators. If the employee 
provides written authorization, the written medical opinion can (and 
must) also contain any limitations on the employee's exposure to 
respirable crystalline silica.
    The PLHCP should discuss the implication of signing or not 
signing the authorization with the employee (in a manner and 
language that he or she understands) so that the employee can make 
an informed decision regarding the written authorization and its 
consequences. The discussion should include the risk of ongoing 
silica exposure, personal risk factors, risk of disease progression, 
and possible health and economic consequences. For instance, written 
authorization is required for a PLHCP to advise an employer that an 
employee should be referred to a Board Certified Specialist in 
Pulmonary Disease or Occupational Medicine for evaluation of an 
abnormal chest X-ray (B-reading 1/0 or greater). If an employee does 
not sign an authorization, then the employer will not know and 
cannot facilitate the referral to a Specialist and is not required 
to pay for the Specialist's examination. In the rare case where an 
employee is diagnosed with acute or accelerated silicosis, co-
workers are likely to be at significant risk of developing those 
diseases as a result of inadequate controls in the workplace. In 
this case, the PLHCP and/or Specialist should explain this concern 
to the affected employee and make a determined effort to obtain 
written authorization from the employee so that the PLHCP and/or 
Specialist can contact the employer.
    Finally, without written authorization from the employee, the 
PLHCP and/or Board Certified Specialist in Pulmonary Disease or 
Occupational Medicine cannot provide feedback to an employer 
regarding control of workplace silica exposure, at least in relation 
to an individual employee. However, the regulation does not prohibit 
a PLHCP and/or Specialist from providing an employer with general 
recommendations regarding exposure controls and prevention programs 
in relation to silica exposure and silica-related illnesses, based 
on the information that the PLHCP receives from the employer such as 
employees' duties and exposure levels. Recommendations may include 
increased frequency of medical surveillance examinations, additional 
medical surveillance components, engineering and work practice 
controls, exposure monitoring and personal protective equipment. For 
instance, more frequent medical surveillance examinations may be a 
recommendation to employers for employees who do abrasive blasting 
with silica because of the high exposures associated with that 
operation.
    ACOEM's Code of Ethics and discussion is a good resource to 
guide PLHCPs regarding the issues discussed in this section (See 
Section 5 of this Appendix).

5. Resources

    5.1. American College of Occupational and Environmental Medicine 
(ACOEM):

ACOEM Code of Ethics. Accessed at: http://www.acoem.org/codeofconduct.aspx
Raymond, L.W. and Wintermeyer, S. (2006) ACOEM evidenced-based 
statement on medical surveillance of silica-exposed workers: Medical 
surveillance of workers exposed to crystalline silica. J Occup 
Environ Med, 48, 95-101.

    5.2. Center for Disease Control and Prevention (CDC)

Tuberculosis Web page: http://www.cdc.gov/tb/default.htm
State TB Control Offices Web page: http://www.cdc.gov/tb/links/tboffices.htm
Tuberculosis Laws and Policies Web page: http://www.cdc.gov/tb/programs/laws/default.htm
CDC. (2013). Latent Tuberculosis Infection: A Guide for Primary 
Health Care Providers. Accessed at: http://www.cdc.gov/tb/publications/ltbi/pdf/targetedltbi.pdf

    5.3. International Labour Organization

International Labour Office (ILO). (2011) Guidelines for the use of 
the ILO International Classification of Radiographs of 
Pneumoconioses, Revised edition 2011. Occupational Safety and Health 
Series No. 22: http://www.ilo.org/safework/info/publications/WCMS_168260/lang-en/index.htm

    5.4. National Institute of Occupational Safety and Health 
(NIOSH)

NIOSH B Reader Program Web page. (Information on interpretation of 
X-rays for silicosis and a list of certified B-readers). Accessed 
at: http://www.cdc.gov/niosh/topics/chestradiography/breader-info.html
NIOSH Guideline (2011). Application of Digital Radiography for the 
Detection and Classification of Pneumoconiosis. NIOSH publication 
number 2011-198. Accessed at: http://www.cdc.gov/niosh/docs/2011-198/.
NIOSH Hazard Review (2002), Health Effects of Occupational Exposure 
to Respirable Crystalline Silica. NIOSH publication number 2002-129: 
Accessed at http://www.cdc.gov/niosh/docs/2002-129/
NIOSH Health Hazard Evaluations Programs. (Information on the NIOSH 
Health Hazard Evaluation (HHE) program, how to request an HHE and 
how to look up an HHE report). Accessed at: http://www.cdc.gov/niosh/hhe/

    5.5. National Industrial Sand Association:

Occupational Health Program for Exposure to Crystalline Silica in 
the Industrial Sand Industry. National Industrial Sand Association, 
2nd ed. 2010. Can be ordered at: http://www.sand.org/silica-occupational-health-program

    5.6. Occupational Safety and Health Administration (OSHA)

Contacting OSHA: http://www.osha.gov/html/Feed_Back.html
OSHA's Clinicians Web page. (OSHA resources, regulations and links 
to help clinicians navigate OSHA's Web site and aid clinicians in 
caring for workers.) Accessed at: http://www.osha.gov/dts/oom/clinicians/index.html
OSHA's Safety and Health Topics Web page on Silica. Accessed at: 
http://www.osha.gov/dsg/topics/silicacrystalline/index.html
OSHA (2013). Spirometry Testing in Occupational Health Programs: 
Best Practices for Healthcare Professionals. (OSHA 3637-03 2013). 
Accessed at: http://www.osha.gov/Publications/OSHA3637.pdf
OSHA/NIOSH (2011). Spirometry: OSHA/NIOSH Spirometry InfoSheet (OSHA 
3415-1-11). (Provides guidance to employers). Accessed at http://www.osha.gov/Publications/osha3415.pdf
OSHA/NIOSH (2011) Spirometry: OSHA/NIOSH Spirometry Worker Info. 
(OSHA 3418-3-11). Accessed at http://www.osha.gov/Publications/osha3418.pdf

    5.7. Other
Steenland, K. and Ward E. (2014). Silica: A lung carcinogen. CA 
Cancer J Clin, 64, 63-69. (This article reviews not only silica and 
lung cancer but also all the known silica-related health effects. 
Further, the authors provide guidance to clinicians on medical 
surveillance of silica-exposed workers and worker counselling on 
safety practices to minimize silica exposure.)

6. References

American Thoracic Society (ATS). Medical Section of the American 
Lung Association (1997). Adverse effects of crystalline silica 
exposure. Am J Respir Crit Care Med, 155, 761-765.
American Thoracic Society (ATS), Centers for Disease Control (CDC), 
Infectious Diseases Society of America (IDSA) (2005). Controlling 
Tuberculosis in the United States. Morbidity and Mortality Weekly 
Report (MMWR), 54(RR12), 1-81. Accessed at: http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5412a1.htm.
Brown, T. (2009). Silica exposure, smoking, silicosis and lung 
cancer--complex interactions. Occupational Medicine, 59, 89-95.
Halldin, C.N., Petsonk, E.L., and Laney, A.S. (2014). Validation of 
the International Labour Office digitized standard images for 
recognition and classification of radiographs of pneumoconiosis. 
Acad Radiol, 21, 305-311.

[[Page 16871]]

International Agency for Research on Cancer. (2012). Monographs on 
the evaluation of carcinogenic risks to humans: Arsenic, Metals, 
Fibers, and Dusts Silica Dust, Crystalline, in the Form of Quartz or 
Cristobalite. A Review of Human Carcinogens. Volume 100 C. Geneva, 
Switzerland: World Health Organization.
Jalloul, A.S. and Banks D.E. (2007). Chapter 23. The health effects 
of silica exposure. In: Rom, W.N. and Markowitz, S.B. (Eds). 
Environmental and Occupational Medicine, 4th edition. Lippincott, 
Williams and Wilkins, Philadelphia, 365-387.
Kramer, M.R., Blanc, P.D., Fireman, E., Amital, A., Guber, A., 
Rahman, N.A., and Shitrit, D. (2012). Artifical stone silicosis: 
Disease resurgence among artificial stone workers. Chest, 142, 419-
424.
Laney, A.S., Petsonk, E.L., and Attfield, M.D. (2011). Intramodality 
and intermodality comparisons of storage phosphor computed 
radiography and conventional film-screen radiography in the 
recognition of small pneumonconiotic opacities. Chest, 140, 1574-
1580.
Liu, Y., Steenland, K., Rong, Y., Hnizdo, E., Huang, X., Zhang, H., 
Shi, T., Sun, Y., Wu, T., and Chen, W. (2013). Exposure-response 
analysis and risk assessment for lung cancer in relationship to 
silica exposure: A 44-year cohort study of 34,018 workers. Am J Epi, 
178, 1424-1433.
Liu, Y., Rong, Y., Steenland, K., Christiani, D.C., Huang, X., Wu, 
T., and Chen, W. (2014). Long-term exposure to crystalline silica 
and risk of heart disease mortality. Epidemiology, 25, 689-696.
Mazurek, G.H., Jereb, J., Vernon, A., LoBue, P., Goldberg, S., 
Castro, K. (2010). Updated guidelines for using interferon gamma 
release assays to detect Mycobacterium tuberculosis infection--
United States. Morbidity and Mortality Weekly Report (MMWR), 
59(RR05), 1-25.
Miller, M.R., Hankinson, J., Brusasco, V., Burgos, F., Casaburi, R., 
Coates, A., Crapo, R., Enright, P., van der Grinten, C.P., 
Gustafsson, P., Jensen, R., Johnson, D.C., MacIntyre, N., McKay, R., 
Navajas, D., Pedersen, O.F., Pellegrino, R., Viegi, G., and Wanger, 
J. (2005).
American Thoracic Society/European Respiratory Society (ATS/ERS) 
Task Force: Standardisation of Spirometry. Eur Respir J, 26, 319-
338.
National Toxicology Program (NTP) (2014). Report on Carcinogens, 
Thirteenth Edition. Silica, Crystalline (respirable Size). Research 
Triangle Park, NC: U.S. Department of Health and Human Services, 
Public Health Service. http://ntp.niehs.nih.gov/ntp/roc/content/profiles/silica.pdf.
Occupational Safety and Health Administration/National Institute for 
Occupational Safety and Health (OSHA/NIOSH) (2012). Hazard Alert. 
Worker exposure to silica during hydraulic fracturing.
Occupational Safety and Health Administration/National Institute for 
Occupational Safety and Health (OSHA/NIOSH) (2015). Hazard alert. 
Worker exposure to silica during countertop manufacturing, 
finishing, and installation. (OSHA-HA-3768-2015).
Redlich, C.A., Tarlo, S.M., Hankinson, J.L., Townsend, M.C, 
Eschenbacher, W.L., Von Essen, S.G., Sigsgaard, T., Weissman, D.N. 
(2014). Official American Thoracic Society technical standards: 
Spirometry in the occupational setting. Am J Respir Crit Care Med; 
189, 984-994.
Rees, D. and Murray, J. (2007). Silica, silicosis and tuberculosis. 
Int J Tuberc Lung Dis, 11(5), 474-484.
Shtraichman, O., Blanc, P.D., Ollech, J.E., Fridel, L., Fuks, L., 
Fireman, E., and Kramer, M.R. (2015). Outbreak of autoimmune disease 
in silicosis linked to artificial stone. Occup Med, 65, 444-450.
Slater, M.L., Welland, G., Pai, M., Parsonnet, J., and Banaei, N. 
(2013). Challenges with QuantiFERON-TB gold assay for large-scale, 
routine screening of U.S. healthcare workers. Am J Respir Crit Care 
Med, 188, 1005-1010.
Steenland, K., Mannetje, A., Boffetta, P., Stayner, L., Attfield, 
M., Chen, J., Dosemeci, M., DeKlerk, N., Hnizdo, E., Koskela, R., 
and Checkoway, H. (2001). International Agency for Research on 
Cancer. Pooled exposure-response analyses and risk assessment for 
lung cancer in 10 cohorts of silica-exposed workers: An IARC 
multicentre study. Cancer Causes Control, 12(9):773-84.
Steenland, K. and Ward E. (2014). Silica: A lung carcinogen. CA 
Cancer J Clin, 64, 63-69.
Townsend, M.C. ACOEM Guidance Statement. (2011). Spirometry in the 
occupational health setting--2011 Update. J Occup Environ Med, 53, 
569-584.

7. Sample Forms

    Three sample forms are provided. The first is a sample written 
medical report for the employee. The second is a sample written 
medical opinion for the employer. And the third is a sample written 
authorization form that employees sign to clarify what information 
the employee is authorizing to be released to the employer.
BILLING CODE 4510-26-P

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BILLING CODE 4510-26-C

PART 1915--OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR SHIPYARD 
EMPLOYMENT

0
5. The authority citation for part 1915 is revised to read as follows:

    Authority:  Section 41, Longshore and Harbor Workers' 
Compensation Act (33 U.S.C. 941); Sections 4, 6, and 8 of the 
Occupational Safety and Health Act of 1970 (29 U.S.C. 653, 655, 
657); Secretary of Labor's Order No. 12-71 (36 FR 8754), 8-76 (41 FR 
25059), 9-83 (48 FR 35736), 1-90 (55 FR 9033), 6-96 (62 FR 111), 3-
2000 (65 FR 50017), 5-2002 (67 FR 65008), 5-2007 (72 FR 31160), 4-
2010 (75 FR 55355), or 1-2012 (77 FR 3912), as applicable; 29 CFR 
part 1911.
    Sections 1915.120 and 1915.152 of 29 CFR also issued under 29 
CFR part 1911.


0
6. In Sec.  1915.1000, amend Table Z by:
0
a. Revising the entries for ``Silica, crystalline cristobalite, 
respirable dust'', ``Silica, crystalline quartz, respirable

[[Page 16875]]

dust'', ``Silica, crystalline tripoli (as quartz), respirable dust'', 
and ``Silica, crystalline tridymite, respirable dust'';
0
b. Under the ``MINERAL DUSTS'' heading of the table, revising the entry 
for ``Silica: Cystalline Quartz'';
0
c. Adding footnote 5; and
0
d. Add footnote p.
    The revisions and additions should read as follows:


Sec.  1915.1000  Air contaminants.

* * * * *

                                               Table Z--Shipyards
----------------------------------------------------------------------------------------------------------------
                                                                                                       Skin
                    Substance                        CAS No.d         ppm a *       mg/m 3 b *      designation
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
Silica, crystalline, respirable dust
    Cristobalite; see 1915.1053.................      14464-46-1
    Quartz; see 1915.1053 5.....................      14808-60-7
    Tripoli (as quartz); see 1915.1053 5........       1317-95-9
    Trydimite; see 1915.1053....................      15468-32-3
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
                                                  Mineral Dusts
----------------------------------------------------------------------------------------------------------------
                    Substance                                                                        mppcf (j)
----------------------------------------------------------------------------------------------------------------
SILICA:
    Crystalline.................................................................................         250 (k)
                                                                                                 ---------------
Quartz. Threshold Limit calculated from the formula (p).........................................        % SiO2+5
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
 * * * * * * *
\5\ See Mineral Dusts table for the exposure limit for any operations or sectors where the exposure limit in
  Sec.   1915.1053 is stayed or is otherwise not in effect.
* The PELs are 8-hour TWAs unless otherwise noted; a (C) designation denotes a ceiling limit. They are to be
  determined from breathing-zone air samples.
a Parts of vapor or gas per million parts of contaminated air by volume at 25 [deg]C and 760 torr.
b Milligrams of substance per cubic meter of air. When entry is in this column only, the value is exact; when
  listed with a ppm entry, it is approximate.
 * * * * * * *
p This standard applies to any operations or sectors for which the respirable crystalline silica standard,
  1915.1053, is stayed or otherwise is not in effect.


0
7. Add Sec.  1915.1053 to read as follows:


Sec.  1915.1053  Respirable crystalline silica.

    The requirements applicable to shipyard employment under this 
section are identical to those set forth at Sec.  1910.1053 of this 
chapter.

PART 1926--SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION

Subpart D--Occupational Health and Environmental Controls

0
8. The authority citation for subpart D of part 1926 is revised to read 
as follows:

    Authority:  Section 107 of the Contract Work Hours and Safety 
Standards Act (40 U.S.C. 3704); Sections 4, 6, and 8 of the 
Occupational Safety and Health Act of 1970 (29 U.S.C. 653, 655, 
657); and Secretary of Labor's Order No. 12-71 (36 FR 8754), 8-76 
(41 FR 25059), 9-83 (48 FR 35736), 1-90 (55 FR 9033), 6-96 (62 FR 
111), 3-2000 (65 FR 50017), 5-2002 (67 FR 65008), 5-2007 (72 FR 
31160), 4-2010 (75 FR 55355), or 1-2012 (77 FR 3912), as applicable; 
and 29 CFR part 1911.
    Sections 1926.58, 1926.59, 1926.60, and 1926.65 also issued 
under 5 U.S.C. 553 and 29 CFR part 1911.
    Section 1926.61 also issued under 49 U.S.C. 1801-1819 and 6 
U.S.C. 553.
    Section 1926.62 also issued under section 1031 of the Housing 
and Community Development Act of 1992 (42 U.S.C. 4853).
    Section 1926.65 also issued under section 126 of the Superfund 
Amendments and Reauthorization Act of 1986, as amended (reprinted at 
29 U.S.C.A. 655 Note), and 5 U.S.C. 553.


0
9. In Sec.  1926.55, amend appendix A:
0
a. By revising the entries for ``Silica, crystalline cristobalite, 
respirable dust'', ``Silica, crystalline quartz, respirable dust'', 
``Silica, crystalline tripoli (as quartz), respirable dust'', and 
``Silica, crystalline tridymite, respirable dust'';
0
b. Under the ``MINERAL DUSTS'' heading of the table, by revising the 
entry for ``Silica: Cystalline Quartz'' in column 1;
0
c. Adding footnote 5; and
0
d. Adding footnote p .
    The revisions and additions read as follows:


Sec.  1926.55  Gases, vapors, fumes, dusts, and mists.

* * * * *

Appendix A to Sec.  1926.55--1970 American Conference of Governmental 
Industrial Hygienists' Threshold Limit Values of Airborne Contaminants

                        Threshold Limit Values of Airborne Contaminants for Construction
----------------------------------------------------------------------------------------------------------------
                                                                                                       Skin
                    Substance                        CAS No.d         ppm a *       mg/m 3 b *      designation
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
Silica, crystalline, respirable dust

[[Page 16876]]

 
    Cristobalite; see 1926.1153.................      14464-46-1  ..............  ..............  ..............
    Quartz; see 1926.11153 5....................      14808-60-7  ..............  ..............  ..............
    Tripoli (as quartz); see 1926.1153 5........       1317-95-9  ..............  ..............  ..............
    Trydimite; see 1926.1153....................      15468-32-3  ..............  ..............  ..............
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
                                                  Mineral Dusts
----------------------------------------------------------------------------------------------------------------
SILICA:
    Crystalline.................................................................................         250 (k)
                                                                                                 ---------------
Quartz. Threshold Limit calculated from the formula (p).........................................        % SiO2+5
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
Footnotes.
 * * * * * * *
\5\ See Mineral Dusts table for the exposure limit for any operations or sectors where the exposure limit in
  Sec.   1926.1153 is stayed or is otherwise not in effect.
 * * * * * * *
a Parts of vapor or gas per million parts of contaminated air by volume at 25 [deg]C and 760 torr.
b Milligrams of substance per cubic meter of air. When entry is in this column only, the value is exact; when
  listed with a ppm entry, it is approximate.
 * * * * * * *
d The CAS number is for information only. Enforcement is based on the substance name. For an entry covering more
  than one metal compound, measured as the metal, the CAS number for the metal is given--not CAS numbers for the
  individual compounds.
 * * * * * * *
p This standard applies to any operations or sectors for which the respirable crystalline silica standard,
  1926.1153, is stayed or otherwise is not in effect.

Subpart Z--Toxic and Hazardous Substances

0
10. The authority for subpart Z of part 1926 is revised to read as 
follows:

    Authority: Section 107 of the Contract Work Hours and Safety 
Standards Act (40 U.S.C. 3704); Sections 4, 6, and 8 of the 
Occupational Safety and Health Act of 1970 (29 U.S.C. 653, 655, 
657); and Secretary of Labor's Order No. 12-71 (36 FR 8754), 8-76 
(41 FR 25059), 9-83 (48 FR 35736), 1-90 (55 FR 9033), 6-96 (62 FR 
111), 3-2000 (65 FR 50017), 5-2002 (67 FR 65008), 5-2007 (72 FR 
31160), 4-2010 (75 FR 55355), or 1-2012 (77 FR 3912), as applicable; 
and 29 CFR part 1911.
    Section 1926.1102 not issued under 29 U.S.C. 655 or 29 CFR part 
1911; also issued under 5 U.S.C. 553.


0
11. Add Sec.  1926.1153 to read as follows:


Sec.  1926.1153  Respirable crystalline silica.

    (a) Scope and application. This section applies to all occupational 
exposures to respirable crystalline silica in construction work, except 
where employee exposure will remain below 25 micrograms per cubic meter 
of air (25 [mu]g/m\3\) as an 8-hour time-weighted average (TWA) under 
any foreseeable conditions.
    (b) Definitions. For the purposes of this section the following 
definitions apply:
    Action level means a concentration of airborne respirable 
crystalline silica of 25 [mu]g/m\3\, calculated as an 8-hour TWA.
    Assistant Secretary means the Assistant Secretary of Labor for 
Occupational Safety and Health, U.S. Department of Labor, or designee.
    Director means the Director of the National Institute for 
Occupational Safety and Health (NIOSH), U.S. Department of Health and 
Human Services, or designee.
    Competent person means an individual who is capable of identifying 
existing and foreseeable respirable crystalline silica hazards in the 
workplace and who has authorization to take prompt corrective measures 
to eliminate or minimize them. The competent person must have the 
knowledge and ability necessary to fulfill the responsibilities set 
forth in paragraph (g) of this section.
    Employee exposure means the exposure to airborne respirable 
crystalline silica that would occur if the employee were not using a 
respirator.
    High-efficiency particulate air [HEPA] filter means a filter that 
is at least 99.97 percent efficient in removing mono-dispersed 
particles of 0.3 micrometers in diameter.
    Objective data means information, such as air monitoring data from 
industry-wide surveys or calculations based on the composition of a 
substance, demonstrating employee exposure to respirable crystalline 
silica associated with a particular product or material or a specific 
process, task, or activity. The data must reflect workplace conditions 
closely resembling or with a higher exposure potential than the 
processes, types of material, control methods, work practices, and 
environmental conditions in the employer's current operations.
    Physician or other licensed health care professional [PLHCP] means 
an individual whose legally permitted scope of practice (i.e., license, 
registration, or certification) allows him or her to independently 
provide or be delegated the responsibility to provide some or all of 
the particular health care services required by paragraph (h) of this 
section.
    Respirable crystalline silica means quartz, cristobalite, and/or 
tridymite contained in airborne particles that are determined to be 
respirable by a sampling device designed to meet the characteristics 
for respirable-particle-size-selective samplers specified in the 
International Organization for Standardization (ISO) 7708:1995: Air 
Quality--Particle Size Fraction Definitions for Health-Related 
Sampling.
    Specialist means an American Board Certified Specialist in 
Pulmonary Disease or an American Board Certified Specialist in 
Occupational Medicine.
    This section means this respirable crystalline silica standard, 29 
CFR 1926.1153.
    (c) Specified exposure control methods. (1) For each employee 
engaged in a task identified on Table 1, the

[[Page 16877]]

employer shall fully and properly implement the engineering controls, 
work practices, and respiratory protection specified for the task on 
Table 1, unless the employer assesses and limits the exposure of the 
employee to respirable crystalline silica in accordance with paragraph 
(d) of this section.

      Table 1--Specified Exposure Control Methods When Working With Materials Containing Crystalline Silica
----------------------------------------------------------------------------------------------------------------
                                                                  Required respiratory protection and minimum
                                      Engineering and work             assigned protection factor (APF)
          Equipment/task            practice control methods ---------------------------------------------------
                                                                   <=4 hours/shift           >4 hours/shift
----------------------------------------------------------------------------------------------------------------
(i) Stationary masonry saws......  Use saw equipped with      None....................  None.
                                    integrated water
                                    delivery system that
                                    continuously feeds water
                                    to the blade.
                                   Operate and maintain tool
                                    in accordance with
                                    manufacturer's
                                    instructions to minimize
                                    dust emissions.
(ii) Handheld power saws (any      Use saw equipped with
 blade diameter).                   integrated water
                                    delivery system that
                                    continuously feeds water
                                    to the blade.
                                   Operate and maintain tool
                                    in accordance with
                                    manufacturer's
                                    instructions to minimize
                                    dust emissions:
                                      --When used outdoors..  None....................  APF 10.
                                      --When used indoors or  APF 10..................  APF 10.
                                       in an enclosed area.
(iii) Handheld power saws for      For tasks performed
 cutting fiber-cement board (with   outdoors only:            None....................  None.
 blade diameter of 8 inches or     Use saw equipped with
 less).                             commercially available
                                    dust collection system.
                                   Operate and maintain tool
                                    in accordance with
                                    manufacturer's
                                    instructions to minimize
                                    dust emissions.
                                   Dust collector must
                                    provide the air flow
                                    recommended by the tool
                                    manufacturer, or
                                    greater, and have a
                                    filter with 99% or
                                    greater efficiency.
(iv) Walk-behind saws............  Use saw equipped with
                                    integrated water
                                    delivery system that
                                    continuously feeds water
                                    to the blade.
                                   Operate and maintain tool
                                    in accordance with
                                    manufacturer's
                                    instructions to minimize
                                    dust emissions:
                                      --When used outdoors..  None....................  None.
                                      --When used indoors or  APF 10..................  APF 10.
                                       in an enclosed area.
(v) Drivable saws................  For tasks performed
                                    outdoors only:
                                   Use saw equipped with      None....................  None.
                                    integrated water
                                    delivery system that
                                    continuously feeds water
                                    to the blade.
                                   Operate and maintain tool
                                    in accordance with
                                    manufacturer's
                                    instructions to minimize
                                    dust emissions.
(vi) Rig-mounted core saws or      Use tool equipped with     None....................  None.
 drills.                            integrated water
                                    delivery system that
                                    supplies water to
                                    cutting surface.
                                   Operate and maintain tool
                                    in accordance with
                                    manufacturer's
                                    instructions to minimize
                                    dust emissions.
(vii) Handheld and stand-mounted   Use drill equipped with    None....................  None.
 drills (including impact and       commercially available
 rotary hammer drills).             shroud or cowling with
                                    dust collection system.
                                   Operate and maintain tool
                                    in accordance with
                                    manufacturer's
                                    instructions to minimize
                                    dust emissions.
                                   Dust collector must
                                    provide the air flow
                                    recommended by the tool
                                    manufacturer, or
                                    greater, and have a
                                    filter with 99% or
                                    greater efficiency and a
                                    filter-cleaning
                                    mechanism.
                                   Use a HEPA-filtered
                                    vacuum when cleaning
                                    holes.
(viii) Dowel drilling rigs for     For tasks performed
 concrete.                          outdoors only:
                                   Use shroud around drill    APF 10..................  APF 10.
                                    bit with a dust
                                    collection system. Dust
                                    collector must have a
                                    filter with 99% or
                                    greater efficiency and a
                                    filter-cleaning
                                    mechanism.
                                   Use a HEPA-filtered
                                    vacuum when cleaning
                                    holes.
(ix) Vehicle-mounted drilling      Use dust collection        None....................  None.
 rigs for rock and concrete.        system with close
                                    capture hood or shroud
                                    around drill bit with a
                                    low-flow water spray to
                                    wet the dust at the
                                    discharge point from the
                                    dust collector.
                                   OR
                                   Operate from within an     None....................  None.
                                    enclosed cab and use
                                    water for dust
                                    suppression on drill bit.
(x) Jackhammers and handheld       Use tool with water
 powered chipping tools.            delivery system that
                                    supplies a continuous
                                    stream or spray of water
                                    at the point of impact:
                                      --When used outdoors..  None....................  APF 10.
                                      --When used indoors or  APF 10..................  APF 10.
                                       in an enclosed area.
                                   OR
                                   Use tool equipped with
                                    commercially available
                                    shroud and dust
                                    collection system.
                                   Operate and maintain tool
                                    in accordance with
                                    manufacturer's
                                    instructions to minimize
                                    dust emissions.

[[Page 16878]]

 
                                   Dust collector must
                                    provide the air flow
                                    recommended by the tool
                                    manufacturer, or
                                    greater, and have a
                                    filter with 99% or
                                    greater efficiency and a
                                    filter-cleaning
                                    mechanism:
                                      --When used outdoors..  None....................  APF 10.
                                      --When used indoors or  APF 10..................  APF 10.
                                       in an enclosed area.
(xi) Handheld grinders for mortar  Use grinder equipped with  APF 10..................  APF 25.
 removal (i.e., tuckpointing).      commercially available
                                    shroud and dust
                                    collection system.
                                   Operate and maintain tool
                                    in accordance with
                                    manufacturer's
                                    instructions to minimize
                                    dust emissions.
                                   Dust collector must
                                    provide 25 cubic feet
                                    per minute (cfm) or
                                    greater of airflow per
                                    inch of wheel diameter
                                    and have a filter with
                                    99% or greater
                                    efficiency and a
                                    cyclonic pre-separator
                                    or filter-cleaning
                                    mechanism.
(xii) Handheld grinders for uses   For tasks performed        None....................  None.
 other than mortar removal.         outdoors only:
                                   Use grinder equipped with
                                    integrated water
                                    delivery system that
                                    continuously feeds water
                                    to the grinding surface.
                                   Operate and maintain tool
                                    in accordance with
                                    manufacturer's
                                    instructions to minimize
                                    dust emissions.
                                   OR
                                   Use grinder equipped with
                                    commercially available
                                    shroud and dust
                                    collection system.
                                   Operate and maintain tool
                                    in accordance with
                                    manufacturer's
                                    instructions to minimize
                                    dust emissions.
                                   Dust collector must
                                    provide 25 cubic feet
                                    per minute (cfm) or
                                    greater of airflow per
                                    inch of wheel diameter
                                    and have a filter with
                                    99% or greater
                                    efficiency and a
                                    cyclonic pre-separator
                                    or filter-cleaning
                                    mechanism:
                                      --When used outdoors..  None....................  None.
                                      --When used indoors or  None....................  APF 10.
                                       in an enclosed area.
(xiii) Walk-behind milling         Use machine equipped with  None....................  None.
 machines and floor grinders.       integrated water
                                    delivery system that
                                    continuously feeds water
                                    to the cutting surface.
                                   Operate and maintain tool
                                    in accordance with
                                    manufacturer's
                                    instructions to minimize
                                    dust emissions.
                                   OR
                                   Use machine equipped with  None....................  None.
                                    dust collection system
                                    recommended by the
                                    manufacturer.
                                   Operate and maintain tool
                                    in accordance with
                                    manufacturer's
                                    instructions to minimize
                                    dust emissions.
                                   Dust collector must
                                    provide the air flow
                                    recommended by the
                                    manufacturer, or
                                    greater, and have a
                                    filter with 99% or
                                    greater efficiency and a
                                    filter-cleaning
                                    mechanism.
                                   When used indoors or in
                                    an enclosed area, use a
                                    HEPA-filtered vacuum to
                                    remove loose dust in
                                    between passes.
(xiv) Small drivable milling       Use a machine equipped     None....................  None.
 machines (less than half-lane).    with supplemental water
                                    sprays designed to
                                    suppress dust. Water
                                    must be combined with a
                                    surfactant.
                                   Operate and maintain
                                    machine to minimize dust
                                    emissions.
(xv) Large drivable milling        For cuts of any depth on   None....................  None.
 machines (half-lane and larger).   asphalt only:
                                   Use machine equipped with
                                    exhaust ventilation on
                                    drum enclosure and
                                    supplemental water
                                    sprays designed to
                                    suppress dust.
                                   Operate and maintain
                                    machine to minimize dust
                                    emissions.
                                   For cuts of four inches
                                    in depth or less on any
                                    substrate:
                                   Use machine equipped with  None....................  None.
                                    exhaust ventilation on
                                    drum enclosure and
                                    supplemental water
                                    sprays designed to
                                    suppress dust.
                                   Operate and maintain
                                    machine to minimize dust
                                    emissions.
                                   OR
                                   Use a machine equipped     None....................  None.
                                    with supplemental water
                                    spray designed to
                                    suppress dust. Water
                                    must be combined with a
                                    surfactant.
                                   Operate and maintain
                                    machine to minimize dust
                                    emissions.
(xvi) Crushing machines..........  Use equipment designed to  None....................  None.
                                    deliver water spray or
                                    mist for dust
                                    suppression at crusher
                                    and other points where
                                    dust is generated (e.g.,
                                    hoppers, conveyers,
                                    sieves/sizing or
                                    vibrating components,
                                    and discharge points).
                                   Operate and maintain
                                    machine in accordance
                                    with manufacturer's
                                    instructions to minimize
                                    dust emissions.
                                   Use a ventilated booth
                                    that provides fresh,
                                    climate-controlled air
                                    to the operator, or a
                                    remote control station.

[[Page 16879]]

 
(xvii) Heavy equipment and         Operate equipment from     None....................  None.
 utility vehicles used to abrade    within an enclosed cab.   None....................  None.
 or fracture silica-containing     When employees outside of
 materials (e.g., hoe-ramming,      the cab are engaged in
 rock ripping) or used during       the task, apply water
 demolition activities involving    and/or dust suppressants
 silica-containing materials.       as necessary to minimize
                                    dust emissions.
(xviii) Heavy equipment and        Apply water and/or dust    None....................  None.
 utility vehicles for tasks such    suppressants as
 as grading and excavating but      necessary to minimize
 not including: Demolishing,        dust emissions.
 abrading, or fracturing silica-   OR.......................
 containing materials.
                                   When the equipment         None....................  None.
                                    operator is the only
                                    employee engaged in the
                                    task, operate equipment
                                    from within an enclosed
                                    cab.
----------------------------------------------------------------------------------------------------------------

    (2) When implementing the control measures specified in Table 1, 
each employer shall:
    (i) For tasks performed indoors or in enclosed areas, provide a 
means of exhaust as needed to minimize the accumulation of visible 
airborne dust;
    (ii) For tasks performed using wet methods, apply water at flow 
rates sufficient to minimize release of visible dust;
    (iii) For measures implemented that include an enclosed cab or 
booth, ensure that the enclosed cab or booth:
    (A) Is maintained as free as practicable from settled dust;
    (B) Has door seals and closing mechanisms that work properly;
    (C) Has gaskets and seals that are in good condition and working 
properly;
    (D) Is under positive pressure maintained through continuous 
delivery of fresh air;
    (E) Has intake air that is filtered through a filter that is 95% 
efficient in the 0.3-10.0 [micro]m range (e.g., MERV-16 or better); and
    (F) Has heating and cooling capabilities.
    (3) Where an employee performs more than one task on Table 1 during 
the course of a shift, and the total duration of all tasks combined is 
more than four hours, the required respiratory protection for each task 
is the respiratory protection specified for more than four hours per 
shift. If the total duration of all tasks on Table 1 combined is less 
than four hours, the required respiratory protection for each task is 
the respiratory protection specified for less than four hours per 
shift.
    (d) Alternative exposure control methods. For tasks not listed in 
Table 1, or where the employer does not fully and properly implement 
the engineering controls, work practices, and respiratory protection 
described in Table 1:
    (1) Permissible exposure limit (PEL). The employer shall ensure 
that no employee is exposed to an airborne concentration of respirable 
crystalline silica in excess of 50 [mu]g/m\3\, calculated as an 8-hour 
TWA.
    (2) Exposure assessment--(i) General. The employer shall assess the 
exposure of each employee who is or may reasonably be expected to be 
exposed to respirable crystalline silica at or above the action level 
in accordance with either the performance option in paragraph 
(d)(2)(ii) or the scheduled monitoring option in paragraph (d)(2)(iii) 
of this section.
    (ii) Performance option. The employer shall assess the 8-hour TWA 
exposure for each employee on the basis of any combination of air 
monitoring data or objective data sufficient to accurately characterize 
employee exposures to respirable crystalline silica.
    (iii) Scheduled monitoring option. (A) The employer shall perform 
initial monitoring to assess the 8-hour TWA exposure for each employee 
on the basis of one or more personal breathing zone air samples that 
reflect the exposures of employees on each shift, for each job 
classification, in each work area. Where several employees perform the 
same tasks on the same shift and in the same work area, the employer 
may sample a representative fraction of these employees in order to 
meet this requirement. In representative sampling, the employer shall 
sample the employee(s) who are expected to have the highest exposure to 
respirable crystalline silica.
    (B) If initial monitoring indicates that employee exposures are 
below the action level, the employer may discontinue monitoring for 
those employees whose exposures are represented by such monitoring.
    (C) Where the most recent exposure monitoring indicates that 
employee exposures are at or above the action level but at or below the 
PEL, the employer shall repeat such monitoring within six months of the 
most recent monitoring.
    (D) Where the most recent exposure monitoring indicates that 
employee exposures are above the PEL, the employer shall repeat such 
monitoring within three months of the most recent monitoring.
    (E) Where the most recent (non-initial) exposure monitoring 
indicates that employee exposures are below the action level, the 
employer shall repeat such monitoring within six months of the most 
recent monitoring until two consecutive measurements, taken seven or 
more days apart, are below the action level, at which time the employer 
may discontinue monitoring for those employees whose exposures are 
represented by such monitoring, except as otherwise provided in 
paragraph (d)(2)(iv) of this section.
    (iv) Reassessment of exposures. The employer shall reassess 
exposures whenever a change in the production, process, control 
equipment, personnel, or work practices may reasonably be expected to 
result in new or additional exposures at or above the action level, or 
when the employer has any reason to believe that new or additional 
exposures at or above the action level have occurred.

[[Page 16880]]

    (v) Methods of sample analysis. The employer shall ensure that all 
samples taken to satisfy the monitoring requirements of paragraph 
(d)(2) of this section are evaluated by a laboratory that analyzes air 
samples for respirable crystalline silica in accordance with the 
procedures in Appendix A to this section.
    (vi) Employee notification of assessment results. (A) Within five 
working days after completing an exposure assessment in accordance with 
paragraph (d)(2) of this section, the employer shall individually 
notify each affected employee in writing of the results of that 
assessment or post the results in an appropriate location accessible to 
all affected employees.
    (B) Whenever an exposure assessment indicates that employee 
exposure is above the PEL, the employer shall describe in the written 
notification the corrective action being taken to reduce employee 
exposure to or below the PEL.
    (vii) Observation of monitoring. (A) Where air monitoring is 
performed to comply with the requirements of this section, the employer 
shall provide affected employees or their designated representatives an 
opportunity to observe any monitoring of employee exposure to 
respirable crystalline silica.
    (B) When observation of monitoring requires entry into an area 
where the use of protective clothing or equipment is required for any 
workplace hazard, the employer shall provide the observer with 
protective clothing and equipment at no cost and shall ensure that the 
observer uses such clothing and equipment.
    (3) Methods of compliance--(i) Engineering and work practice 
controls. The employer shall use engineering and work practice controls 
to reduce and maintain employee exposure to respirable crystalline 
silica to or below the PEL, unless the employer can demonstrate that 
such controls are not feasible. Wherever such feasible engineering and 
work practice controls are not sufficient to reduce employee exposure 
to or below the PEL, the employer shall nonetheless use them to reduce 
employee exposure to the lowest feasible level and shall supplement 
them with the use of respiratory protection that complies with the 
requirements of paragraph (e) of this section.
    (ii) Abrasive blasting. In addition to the requirements of 
paragraph (d)(3)(i) of this section, the employer shall comply with 
other OSHA standards, when applicable, such as 29 CFR 1926.57 
(Ventilation), where abrasive blasting is conducted using crystalline 
silica-containing blasting agents, or where abrasive blasting is 
conducted on substrates that contain crystalline silica.
    (e) Respiratory protection--(1) General. Where respiratory 
protection is required by this section, the employer must provide each 
employee an appropriate respirator that complies with the requirements 
of this paragraph and 29 CFR 1910.134. Respiratory protection is 
required:
    (i) Where specified by Table 1 of paragraph (c) of this section; or
    (ii) For tasks not listed in Table 1, or where the employer does 
not fully and properly implement the engineering controls, work 
practices, and respiratory protection described in Table 1:
    (A) Where exposures exceed the PEL during periods necessary to 
install or implement feasible engineering and work practice controls;
    (B) Where exposures exceed the PEL during tasks, such as certain 
maintenance and repair tasks, for which engineering and work practice 
controls are not feasible; and
    (C) During tasks for which an employer has implemented all feasible 
engineering and work practice controls and such controls are not 
sufficient to reduce exposures to or below the PEL.
    (2) Respiratory protection program. Where respirator use is 
required by this section, the employer shall institute a respiratory 
protection program in accordance with 29 CFR 1910.134.
    (3) Specified exposure control methods. For the tasks listed in 
Table 1 in paragraph (c) of this section, if the employer fully and 
properly implements the engineering controls, work practices, and 
respiratory protection described in Table 1, the employer shall be 
considered to be in compliance with paragraph (e)(1) of this section 
and the requirements for selection of respirators in 29 CFR 
1910.134(d)(1)(iii) and (d)(3) with regard to exposure to respirable 
crystalline silica.
    (f) Housekeeping. (1) The employer shall not allow dry sweeping or 
dry brushing where such activity could contribute to employee exposure 
to respirable crystalline silica unless wet sweeping, HEPA-filtered 
vacuuming or other methods that minimize the likelihood of exposure are 
not feasible.
    (2) The employer shall not allow compressed air to be used to clean 
clothing or surfaces where such activity could contribute to employee 
exposure to respirable crystalline silica unless:
    (i) The compressed air is used in conjunction with a ventilation 
system that effectively captures the dust cloud created by the 
compressed air; or
    (ii) No alternative method is feasible.
    (g) Written exposure control plan. (1) The employer shall establish 
and implement a written exposure control plan that contains at least 
the following elements:
    (i) A description of the tasks in the workplace that involve 
exposure to respirable crystalline silica;
    (ii) A description of the engineering controls, work practices, and 
respiratory protection used to limit employee exposure to respirable 
crystalline silica for each task;
    (iii) A description of the housekeeping measures used to limit 
employee exposure to respirable crystalline silica; and
    (iv) A description of the procedures used to restrict access to 
work areas, when necessary, to minimize the number of employees exposed 
to respirable crystalline silica and their level of exposure, including 
exposures generated by other employers or sole proprietors.
    (2) The employer shall review and evaluate the effectiveness of the 
written exposure control plan at least annually and update it as 
necessary.
    (3) The employer shall make the written exposure control plan 
readily available for examination and copying, upon request, to each 
employee covered by this section, their designated representatives, the 
Assistant Secretary and the Director.
    (4) The employer shall designate a competent person to make 
frequent and regular inspections of job sites, materials, and equipment 
to implement the written exposure control plan.
    (h) Medical surveillance--(1) General. (i) The employer shall make 
medical surveillance available at no cost to the employee, and at a 
reasonable time and place, for each employee who will be required under 
this section to use a respirator for 30 or more days per year.
    (ii) The employer shall ensure that all medical examinations and 
procedures required by this section are performed by a PLHCP as defined 
in paragraph (b) of this section.
    (2) Initial examination. The employer shall make available an 
initial (baseline) medical examination within 30 days after initial 
assignment, unless the employee has received a medical examination that 
meets the requirements of this section within the last three years. The 
examination shall consist of:
    (i) A medical and work history, with emphasis on: Past, present, 
and anticipated exposure to respirable crystalline silica, dust, and 
other agents affecting the respiratory system; any history of 
respiratory system dysfunction, including signs and

[[Page 16881]]

symptoms of respiratory disease (e.g., shortness of breath, cough, 
wheezing); history of tuberculosis; and smoking status and history;
    (ii) A physical examination with special emphasis on the 
respiratory system;
    (iii) A chest X-ray (a single posteroanterior radiographic 
projection or radiograph of the chest at full inspiration recorded on 
either film (no less than 14 x 17 inches and no more than 16 x 17 
inches) or digital radiography systems), interpreted and classified 
according to the International Labour Office (ILO) International 
Classification of Radiographs of Pneumoconioses by a NIOSH-certified B 
Reader;
    (iv) A pulmonary function test to include forced vital capacity 
(FVC) and forced expiratory volume in one second (FEV1) and 
FEV1/FVC ratio, administered by a spirometry technician with 
a current certificate from a NIOSH-approved spirometry course;
    (v) Testing for latent tuberculosis infection; and
    (vi) Any other tests deemed appropriate by the PLHCP.
    (3) Periodic examinations. The employer shall make available 
medical examinations that include the procedures described in paragraph 
(h)(2) of this section (except paragraph (h)(2)(v)) at least every 
three years, or more frequently if recommended by the PLHCP.
    (4) Information provided to the PLHCP. The employer shall ensure 
that the examining PLHCP has a copy of this standard, and shall provide 
the PLHCP with the following information:
    (i) A description of the employee's former, current, and 
anticipated duties as they relate to the employee's occupational 
exposure to respirable crystalline silica;
    (ii) The employee's former, current, and anticipated levels of 
occupational exposure to respirable crystalline silica;
    (iii) A description of any personal protective equipment used or to 
be used by the employee, including when and for how long the employee 
has used or will use that equipment; and
    (iv) Information from records of employment-related medical 
examinations previously provided to the employee and currently within 
the control of the employer.
    (5) PLHCP's written medical report for the employee. The employer 
shall ensure that the PLHCP explains to the employee the results of the 
medical examination and provides each employee with a written medical 
report within 30 days of each medical examination performed. The 
written report shall contain:
    (i) A statement indicating the results of the medical examination, 
including any medical condition(s) that would place the employee at 
increased risk of material impairment to health from exposure to 
respirable crystalline silica and any medical conditions that require 
further evaluation or treatment;
    (ii) Any recommended limitations on the employee's use of 
respirators;
    (iii) Any recommended limitations on the employee's exposure to 
respirable crystalline silica; and
    (iv) A statement that the employee should be examined by a 
specialist (pursuant to paragraph (h)(7) of this section) if the chest 
X-ray provided in accordance with this section is classified as 1/0 or 
higher by the B Reader, or if referral to a specialist is otherwise 
deemed appropriate by the PLHCP.
    (6) PLHCP's written medical opinion for the employer. (i) The 
employer shall obtain a written medical opinion from the PLHCP within 
30 days of the medical examination. The written opinion shall contain 
only the following:
    (A) The date of the examination;
    (B) A statement that the examination has met the requirements of 
this section; and
    (C) Any recommended limitations on the employee's use of 
respirators.
    (ii) If the employee provides written authorization, the written 
opinion shall also contain either or both of the following:
    (A) Any recommended limitations on the employee's exposure to 
respirable crystalline silica;
    (B) A statement that the employee should be examined by a 
specialist (pursuant to paragraph (h)(7) of this section) if the chest 
X-ray provided in accordance with this section is classified as 1/0 or 
higher by the B Reader, or if referral to a specialist is otherwise 
deemed appropriate by the PLHCP.
    (iii) The employer shall ensure that each employee receives a copy 
of the written medical opinion described in paragraph (h)(6)(i) and 
(ii) of this section within 30 days of each medical examination 
performed.
    (7) Additional examinations. (i) If the PLHCP's written medical 
opinion indicates that an employee should be examined by a specialist, 
the employer shall make available a medical examination by a specialist 
within 30 days after receiving the PLHCP's written opinion.
    (ii) The employer shall ensure that the examining specialist is 
provided with all of the information that the employer is obligated to 
provide to the PLHCP in accordance with paragraph (h)(4) of this 
section.
    (iii) The employer shall ensure that the specialist explains to the 
employee the results of the medical examination and provides each 
employee with a written medical report within 30 days of the 
examination. The written report shall meet the requirements of 
paragraph (h)(5) (except paragraph (h)(5)(iv)) of this section.
    (iv) The employer shall obtain a written opinion from the 
specialist within 30 days of the medical examination. The written 
opinion shall meet the requirements of paragraph (h)(6) (except 
paragraph (h)(6)(i)(B) and (ii)(B)) of this section.
    (i) Communication of respirable crystalline silica hazards to 
employees--(1) Hazard communication. The employer shall include 
respirable crystalline silica in the program established to comply with 
the hazard communication standard (HCS) (29 CFR 1910.1200). The 
employer shall ensure that each employee has access to labels on 
containers of crystalline silica and safety data sheets, and is trained 
in accordance with the provisions of HCS and paragraph (i)(2) of this 
section. The employer shall ensure that at least the following hazards 
are addressed: Cancer, lung effects, immune system effects, and kidney 
effects.
    (2) Employee information and training. (i) The employer shall 
ensure that each employee covered by this section can demonstrate 
knowledge and understanding of at least the following:
    (A) The health hazards associated with exposure to respirable 
crystalline silica;
    (B) Specific tasks in the workplace that could result in exposure 
to respirable crystalline silica;
    (C) Specific measures the employer has implemented to protect 
employees from exposure to respirable crystalline silica, including 
engineering controls, work practices, and respirators to be used;
    (D) The contents of this section;
    (E) The identity of the competent person designated by the employer 
in accordance with paragraph (g)(4) of this section; and
    (F) The purpose and a description of the medical surveillance 
program required by paragraph (h) of this section.
    (ii) The employer shall make a copy of this section readily 
available without cost to each employee covered by this section.
    (j) Recordkeeping--(1) Air monitoring data. (i) The employer shall 
make and

[[Page 16882]]

maintain an accurate record of all exposure measurements taken to 
assess employee exposure to respirable crystalline silica, as 
prescribed in paragraph (d)(2) of this section.
    (ii) This record shall include at least the following information:
    (A) The date of measurement for each sample taken;
    (B) The task monitored;
    (C) Sampling and analytical methods used;
    (D) Number, duration, and results of samples taken;
    (E) Identity of the laboratory that performed the analysis;
    (F) Type of personal protective equipment, such as respirators, 
worn by the employees monitored; and
    (G) Name, social security number, and job classification of all 
employees represented by the monitoring, indicating which employees 
were actually monitored.
    (iii) The employer shall ensure that exposure records are 
maintained and made available in accordance with 29 CFR 1910.1020.
    (2) Objective data. (i) The employer shall make and maintain an 
accurate record of all objective data relied upon to comply with the 
requirements of this section.
    (ii) This record shall include at least the following information:
    (A) The crystalline silica-containing material in question;
    (B) The source of the objective data;
    (C) The testing protocol and results of testing;
    (D) A description of the process, task, or activity on which the 
objective data were based; and
    (E) Other data relevant to the process, task, activity, material, 
or exposures on which the objective data were based.
    (iii) The employer shall ensure that objective data are maintained 
and made available in accordance with 29 CFR 1910.1020.
    (3) Medical surveillance. (i) The employer shall make and maintain 
an accurate record for each employee covered by medical surveillance 
under paragraph (h) of this section.
    (ii) The record shall include the following information about the 
employee:
    (A) Name and social security number;
    (B) A copy of the PLHCPs' and specialists' written medical 
opinions; and
    (C) A copy of the information provided to the PLHCPs and 
specialists.
    (iii) The employer shall ensure that medical records are maintained 
and made available in accordance with 29 CFR 1910.1020.
    (k) Dates. (1) This section shall become effective June 23, 2016.
    (2) All obligations of this section, except requirements for 
methods of sample analysis in paragraph (d)(2)(v), shall commence June 
23, 2017.
    (3) Requirements for methods of sample analysis in paragraph 
(d)(2)(v) of this section commence June 23, 2018.

Appendix A to Sec.  1926.1153--Methods of Sample Analysis

    This This appendix specifies the procedures for analyzing air 
samples for respirable crystalline silica, as well as the quality 
control procedures that employers must ensure that laboratories use 
when performing an analysis required under 29 CFR 1926.1153 
(d)(2)(v). Employers must ensure that such a laboratory:
    1. Evaluates all samples using the procedures specified in one 
of the following analytical methods: OSHA ID-142; NMAM 7500; NMAM 
7602; NMAM 7603; MSHA P-2; or MSHA P-7;
    2. Is accredited to ANS/ISO/IEC Standard 17025:2005 with respect 
to crystalline silica analyses by a body that is compliant with ISO/
IEC Standard 17011:2004 for implementation of quality assessment 
programs;
    3. Uses the most current National Institute of Standards and 
Technology (NIST) or NIST traceable standards for instrument 
calibration or instrument calibration verification;
    4. Implements an internal quality control (QC) program that 
evaluates analytical uncertainty and provides employers with 
estimates of sampling and analytical error;
    5. Characterizes the sample material by identifying polymorphs 
of respirable crystalline silica present, identifies the presence of 
any interfering compounds that might affect the analysis, and makes 
any corrections necessary in order to obtain accurate sample 
analysis; and
    6. Analyzes quantitatively for crystalline silica only after 
confirming that the sample matrix is free of uncorrectable 
analytical interferences, corrects for analytical interferences, and 
uses a method that meets the following performance specifications:
    6.1 Each day that samples are analyzed, performs instrument 
calibration checks with standards that bracket the sample 
concentrations;
    6.2 Uses five or more calibration standard levels to prepare 
calibration curves and ensures that standards are distributed 
through the calibration range in a manner that accurately reflects 
the underlying calibration curve; and
    6.3 Optimizes methods and instruments to obtain a quantitative 
limit of detection that represents a value no higher than 25 percent 
of the PEL based on sample air volume.

Appendix B to Sec.  1926.1153--Medical Surveillance Guidelines

Introduction

    The purpose of this Appendix is to provide medical information 
and recommendations to aid physicians and other licensed health care 
professionals (PLHCPs) regarding compliance with the medical 
surveillance provisions of the respirable crystalline silica 
standard (29 CFR 1926.1153). Appendix B is for informational and 
guidance purposes only and none of the statements in Appendix B 
should be construed as imposing a mandatory requirement on employers 
that is not otherwise imposed by the standard.
    Medical screening and surveillance allow for early 
identification of exposure-related health effects in individual 
employee and groups of employees, so that actions can be taken to 
both avoid further exposure and prevent or address adverse health 
outcomes. Silica-related diseases can be fatal, encompass a variety 
of target organs, and may have public health consequences when 
considering the increased risk of a latent tuberculosis (TB) 
infection becoming active. Thus, medical surveillance of silica-
exposed employees requires that PLHCPs have a thorough knowledge of 
silica-related health effects.
    This Appendix is divided into seven sections. Section 1 reviews 
silica-related diseases, medical responses, and public health 
responses. Section 2 outlines the components of the medical 
surveillance program for employees exposed to silica. Section 3 
describes the roles and responsibilities of the PLHCP implementing 
the program and of other medical specialists and public health 
professionals. Section 4 provides a discussion of considerations, 
including confidentiality. Section 5 provides a list of additional 
resources and Section 6 lists references. Section 7 provides sample 
forms for the written medical report for the employee, the written 
medical opinion for the employer and the written authorization.

1. Recognition of Silica-Related Diseases

    1.1. Overview. The term ``silica'' refers specifically to the 
compound silicon dioxide (SiO2). Silica is a major 
component of sand, rock, and mineral ores. Exposure to fine 
(respirable size) particles of crystalline forms of silica is 
associated with adverse health effects, such as silicosis, lung 
cancer, chronic obstructive pulmonary disease (COPD), and activation 
of latent TB infections. Exposure to respirable crystalline silica 
can occur in industry settings such as foundries, abrasive blasting 
operations, paint manufacturing, glass and concrete product 
manufacturing, brick making, china and pottery manufacturing, 
manufacturing of plumbing fixtures, and many construction activities 
including highway repair, masonry, concrete work, rock drilling, and 
tuck-pointing. New uses of silica continue to emerge. These include 
countertop manufacturing, finishing, and installation (Kramer et al. 
2012; OSHA 2015) and hydraulic fracturing in the oil and gas 
industry (OSHA 2012).
    Silicosis is an irreversible, often disabling, and sometimes 
fatal fibrotic lung disease. Progression of silicosis can occur 
despite removal from further exposure. Diagnosis of silicosis 
requires a history of exposure to silica and radiologic findings 
characteristic of silica exposure. Three different presentations of 
silicosis (chronic, accelerated, and acute) have been defined. 
Accelerated and acute silicosis are much less common than chronic 
silicosis. However, it is critical to recognize all cases of 
accelerated and acute silicosis because these are life-threatening 
illnesses

[[Page 16883]]

and because they are caused by substantial overexposures to 
respirable crystalline silica. Although any case of silicosis 
indicates a breakdown in prevention, a case of acute or accelerated 
silicosis implies current high exposure and a very marked breakdown 
in prevention.
    In addition to silicosis, employees exposed to respirable 
crystalline silica, especially those with accelerated or acute 
silicosis, are at increased risks of contracting active TB and other 
infections (ATS 1997; Rees and Murray 2007). Exposure to respirable 
crystalline silica also increases an employee's risk of developing 
lung cancer, and the higher the cumulative exposure, the higher the 
risk (Steenland et al. 2001; Steenland and Ward 2014). Symptoms for 
these diseases and other respirable crystalline silica-related 
diseases are discussed below.
    1.2. Chronic Silicosis. Chronic silicosis is the most common 
presentation of silicosis and usually occurs after at least 10 years 
of exposure to respirable crystalline silica. The clinical 
presentation of chronic silicosis is:
    1.2.1. Symptoms--shortness of breath and cough, although 
employees may not notice any symptoms early in the disease. 
Constitutional symptoms, such as fever, loss of appetite and 
fatigue, may indicate other diseases associated with silica 
exposure, such as TB infection or lung cancer. Employees with these 
symptoms should immediately receive further evaluation and 
treatment.
    1.2.2. Physical Examination--may be normal or disclose dry rales 
or rhonchi on lung auscultation.
    1.2.3. Spirometry--may be normal or may show only a mild 
restrictive or obstructive pattern.
    1.2.4. Chest X-ray--classic findings are small, rounded 
opacities in the upper lung fields bilaterally. However, small 
irregular opacities and opacities in other lung areas can also 
occur. Rarely, ``eggshell calcifications'' in the hilar and 
mediastinal lymph nodes are seen.
    1.2.5. Clinical Course--chronic silicosis in most cases is a 
slowly progressive disease. Under the respirable crystalline silica 
standard, the PLHCP is to recommend that employees with a 1/0 
category X-ray be referred to an American Board Certified Specialist 
in Pulmonary Disease or Occupational Medicine. The PLHCP and/or 
Specialist should counsel employees regarding work practices and 
personal habits that could affect employees' respiratory health.
    1.3. Accelerated Silicosis. Accelerated silicosis generally 
occurs within 5-10 years of exposure and results from high levels of 
exposure to respirable crystalline silica. The clinical presentation 
of accelerated silicosis is:
    1.3.1. Symptoms--shortness of breath, cough, and sometimes 
sputum production. Employees with exposure to respirable crystalline 
silica, and especially those with accelerated silicosis, are at high 
risk for activation of TB infections, atypical mycobacterial 
infections, and fungal superinfections. Constitutional symptoms, 
such as fever, weight loss, hemoptysis (coughing up blood), and 
fatigue may herald one of these infections or the onset of lung 
cancer.
    1.3.2. Physical Examination--rales, rhonchi, or other abnormal 
lung findings in relation to illnesses present. Clubbing of the 
digits, signs of heart failure, and cor pulmonale may be present in 
severe lung disease.
    1.3.3. Spirometry--restrictive or mixed restrictive/obstructive 
pattern.
    1.3.4. Chest X-ray--small rounded and/or irregular opacities 
bilaterally. Large opacities and lung abscesses may indicate 
infections, lung cancer, or progression to complicated silicosis, 
also termed progressive massive fibrosis.
    1.3.5. Clinical Course--accelerated silicosis has a rapid, 
severe course. Under the respirable crystalline silica standard, the 
PLHCP can recommend referral to a Board Certified Specialist in 
either Pulmonary Disease or Occupational Medicine, as deemed 
appropriate, and referral to a Specialist is recommended whenever 
the diagnosis of accelerated silicosis is being considered.
    1.4. Acute Silicosis. Acute silicosis is a rare disease caused 
by inhalation of extremely high levels of respirable crystalline 
silica particles. The pathology is similar to alveolar proteinosis 
with lipoproteinaceous material accumulating in the alveoli. Acute 
silicosis develops rapidly, often, within a few months to less than 
2 years of exposure, and is almost always fatal. The clinical 
presentation of acute silicosis is as follows:
    1.4.1. Symptoms--sudden, progressive, and severe shortness of 
breath. Constitutional symptoms are frequently present and include 
fever, weight loss, fatigue, productive cough, hemoptysis (coughing 
up blood), and pleuritic chest pain.
    1.4.2. Physical Examination--dyspnea at rest, cyanosis, 
decreased breath sounds, inspiratory rales, clubbing of the digits, 
and fever.
    1.4.3. Spirometry--restrictive or mixed restrictive/obstructive 
pattern.
    1.4.4. Chest X-ray--diffuse haziness of the lungs bilaterally 
early in the disease. As the disease progresses, the ``ground 
glass'' appearance of interstitial fibrosis will appear.
    1.4.5. Clinical Course--employees with acute silicosis are at 
especially high risk of TB activation, nontuberculous mycobacterial 
infections, and fungal superinfections. Acute silicosis is 
immediately life-threatening. The employee should be urgently 
referred to a Board Certified Specialist in Pulmonary Disease or 
Occupational Medicine for evaluation and treatment. Although any 
case of silicosis indicates a breakdown in prevention, a case of 
acute or accelerated silicosis implies a profoundly high level of 
silica exposure and may mean that other employees are currently 
exposed to dangerous levels of silica.
    1.5. COPD. COPD, including chronic bronchitis and emphysema, has 
been documented in silica-exposed employees, including those who do 
not develop silicosis. Periodic spirometry tests are performed to 
evaluate each employee for progressive changes consistent with the 
development of COPD. In addition to evaluating spirometry results of 
individual employees over time, PLHCPs may want to be aware of 
general trends in spirometry results for groups of employees from 
the same workplace to identify possible problems that might exist at 
that workplace. (See Section 2 of this Appendix on Medical 
Surveillance for further discussion.) Heart disease may develop 
secondary to lung diseases such as COPD. A recent study by Liu et 
al. 2014 noted a significant exposure-response trend between 
cumulative silica exposure and heart disease deaths, primarily due 
to pulmonary heart disease, such as cor pulmonale.
    1.6. Renal and Immune System. Silica exposure has been 
associated with several types of kidney disease, including 
glomerulonephritis, nephrotic syndrome, and end stage renal disease 
requiring dialysis. Silica exposure has also been associated with 
other autoimmune conditions, including progressive systemic 
sclerosis, systemic lupus erythematosus, and rheumatoid arthritis. 
Studies note an association between employees with silicosis and 
serologic markers for autoimmune diseases, including antinuclear 
antibodies, rheumatoid factor, and immune complexes (Jalloul and 
Banks 2007; Shtraichman et al. 2015).
    1.7. TB and Other Infections. Silica-exposed employees with 
latent TB are 3 to 30 times more likely to develop active pulmonary 
TB infection (ATS 1997; Rees and Murray 2007). Although respirable 
crystalline silica exposure does not cause TB infection, individuals 
with latent TB infection are at increased risk for activation of 
disease if they have higher levels of respirable crystalline silica 
exposure, greater profusion of radiographic abnormalities, or a 
diagnosis of silicosis. Demographic characteristics, such as 
immigration from some countries, are associated with increased rates 
of latent TB infection. PLHCPs can review the latest Centers for 
Disease Control and Prevention (CDC) information on TB incidence 
rates and high risk populations online (See Section 5 of this 
Appendix). Additionally, silica-exposed employees are at increased 
risk for contracting nontuberculous mycobacterial infections, 
including Mycobacterium avium-intracellulare and Mycobacterium 
kansaii.
    1.8. Lung Cancer. The National Toxicology Program has listed 
respirable crystalline silica as a known human carcinogen since 2000 
(NTP 2014). The International Agency for Research on Cancer (2012) 
has also classified silica as Group 1 (carcinogenic to humans). 
Several studies have indicated that the risk of lung cancer from 
exposure to respirable crystalline silica and smoking is greater 
than additive (Brown 2009; Liu et al. 2013). Employees should be 
counseled on smoking cessation.

2. Medical Surveillance

    PLHCPs who manage silica medical surveillance programs should 
have a thorough understanding of the many silica-related diseases 
and health effects outlined in Section 1 of this Appendix. At each 
clinical encounter, the PLHCP should consider silica-related health 
outcomes, with particular vigilance for acute and accelerated 
silicosis. In this Section, the required components of

[[Page 16884]]

medical surveillance under the respirable crystalline silica 
standard are reviewed, along with additional guidance and 
recommendations for PLHCPs performing medical surveillance 
examinations for silica-exposed employees.
    2.1. History.
    2.1.1. The respirable crystalline silica standard requires the 
following: A medical and work history, with emphasis on: Past, 
present, and anticipated exposure to respirable crystalline silica, 
dust, and other agents affecting the respiratory system; any history 
of respiratory system dysfunction, including signs and symptoms of 
respiratory disease (e.g., shortness of breath, cough, wheezing); 
history of TB; and smoking status and history.
    2.1.2. Further, the employer must provide the PLHCP with the 
following information:
    2.1.2.1. A description of the employee's former, current, and 
anticipated duties as they relate to the employee's occupational 
exposure to respirable crystalline silica;
    2.1.2.2. The employee's former, current, and anticipated levels 
of occupational exposure to respirable crystalline silica;
    2.1.2.3. A description of any personal protective equipment used 
or to be used by the employee, including when and for how long the 
employee has used or will use that equipment; and
    2.1.2.4. Information from records of employment-related medical 
examinations previously provided to the employee and currently 
within the control of the employer.
    2.1.3. Additional guidance and recommendations: A history is 
particularly important both in the initial evaluation and in 
periodic examinations. Information on past and current medical 
conditions (particularly a history of kidney disease, cardiac 
disease, connective tissue disease, and other immune diseases), 
medications, hospitalizations and surgeries may uncover health 
risks, such as immune suppression, that could put an employee at 
increased health risk from exposure to silica. This information is 
important when counseling the employee on risks and safe work 
practices related to silica exposure.
    2.2. Physical Examination.
    2.2.1. The respirable crystalline silica standard requires the 
following: A physical examination, with special emphasis on the 
respiratory system. The physical examination must be performed at 
the initial examination and every three years thereafter.
    2.2.2. Additional guidance and recommendations: Elements of the 
physical examination that can assist the PHLCP include: An 
examination of the cardiac system, an extremity examination (for 
clubbing, cyanosis, edema, or joint abnormalities), and an 
examination of other pertinent organ systems identified during the 
history.
    2.3. TB Testing.
    2.3.1. The respirable crystalline silica standard requires the 
following: Baseline testing for TB on initial examination.
    2.3.2. Additional guidance and recommendations:
    2.3.2.1. Current CDC guidelines (See Section 5 of this Appendix) 
should be followed for the application and interpretation of 
Tuberculin skin tests (TST). The interpretation and documentation of 
TST reactions should be performed within 48 to 72 hours of 
administration by trained PLHCPs.
    2.3.2.2. PLHCPs may use alternative TB tests, such as 
interferon-[gamma] release assays (IGRAs), if sensitivity and 
specificity are comparable to TST (Mazurek et al. 2010; Slater et 
al. 2013). PLHCPs can consult the current CDC guidelines for 
acceptable tests for latent TB infection.
    2.3.2.3. The silica standard allows the PLHCP to order 
additional tests or test at a greater frequency than required by the 
standard, if deemed appropriate. Therefore, PLHCPs might perform 
periodic (e.g., annual) TB testing as appropriate, based on 
employees' risk factors. For example, according to the American 
Thoracic Society (ATS), the diagnosis of silicosis or exposure to 
silica for 25 years or more are indications for annual TB testing 
(ATS 1997). PLHCPs should consult the current CDC guidance on risk 
factors for TB (See Section 5 of this Appendix).
    2.3.2.4. Employees with positive TB tests and those with 
indeterminate test results should be referred to the appropriate 
agency or specialist, depending on the test results and clinical 
picture. Agencies, such as local public health departments, or 
specialists, such as a pulmonary or infectious disease specialist, 
may be the appropriate referral. Active TB is a nationally 
notifiable disease. PLHCPs should be aware of the reporting 
requirements for their region. All States have TB Control Offices 
that can be contacted for further information. (See Section 5 of 
this Appendix for links to CDC's TB resources and State TB Control 
Offices.)
    2.3.2.5. The following public health principles are key to TB 
control in the U.S. (ATS-CDC-IDSA 2005):
    (1) Prompt detection and reporting of persons who have 
contracted active TB;
    (2) Prevention of TB spread to close contacts of active TB 
cases;
    (3) Prevention of active TB in people with latent TB through 
targeted testing and treatment; and
    (4) Identification of settings at high risk for TB transmission 
so that appropriate infection-control measures can be implemented.
    2.4. Pulmonary Function Testing.
    2.4.1. The respirable crystalline silica standard requires the 
following: Pulmonary function testing must be performed on the 
initial examination and every three years thereafter. The required 
pulmonary function test is spirometry and must include forced vital 
capacity (FVC), forced expiratory volume in one second 
(FEV1), and FEV1/FVC ratio. Testing must be 
administered by a spirometry technician with a current certificate 
from a National Institute for Occupational Health and Safety 
(NIOSH)-approved spirometry course.
    2.4.2. Additional guidance and recommendations: Spirometry 
provides information about individual respiratory status and can be 
used to track an employee's respiratory status over time or as a 
surveillance tool to follow individual and group respiratory 
function. For quality results, the ATS and the American College of 
Occupational and Environmental Medicine (ACOEM) recommend use of the 
third National Health and Nutrition Examination Survey (NHANES III) 
values, and ATS publishes recommendations for spirometry equipment 
(Miller et al. 2005; Townsend 2011; Redlich et al. 2014). OSHA's 
publication, Spirometry Testing in Occupational Health Programs: 
Best Practices for Healthcare Professionals, provides helpful 
guidance (See Section 5 of this Appendix). Abnormal spirometry 
results may warrant further clinical evaluation and possible 
recommendations for limitations on the employee's exposure to 
respirable crystalline silica.
    2.5. Chest X-ray.
    2.5.1. The respirable crystalline silica standard requires the 
following: A single posteroanterior (PA) radiographic projection or 
radiograph of the chest at full inspiration recorded on either film 
(no less than 14 x 17 inches and no more than 16 x 17 inches) or 
digital radiography systems. A chest X-ray must be performed on the 
initial examination and every three years thereafter. The chest X-
ray must be interpreted and classified according to the 
International Labour Office (ILO) International Classification of 
Radiographs of Pneumoconioses by a NIOSH-certified B Reader.
    Chest radiography is necessary to diagnose silicosis, monitor 
the progression of silicosis, and identify associated conditions 
such as TB. If the B reading indicates small opacities in a 
profusion of 1/0 or higher, the employee is to receive a 
recommendation for referral to a Board Certified Specialist in 
Pulmonary Disease or Occupational Medicine.
    2.5.2. Additional guidance and recommendations: Medical imaging 
has largely transitioned from conventional film-based radiography to 
digital radiography systems. The ILO Guidelines for the 
Classification of Pneumoconioses has historically provided film-
based chest radiography as a referent standard for comparison to 
individual exams. However, in 2011, the ILO revised the guidelines 
to include a digital set of referent standards that were derived 
from the prior film-based standards. To assist in assuring that 
digitally-acquired radiographs are at least as safe and effective as 
film radiographs, NIOSH has prepared guidelines, based upon accepted 
contemporary professional recommendations (See Section 5 of this 
Appendix). Current research from Laney et al. 2011 and Halldin et 
al. 2014 validate the use of the ILO digital referent images. Both 
studies conclude that the results of pneumoconiosis classification 
using digital references are comparable to film-based ILO 
classifications. Current ILO guidance on radiography for 
pneumoconioses and B-reading should be reviewed by the PLHCP 
periodically, as needed, on the ILO or NIOSH Web sites (See Section 
5 of this Appendix).
    2.6. Other Testing. Under the respirable crystalline silica 
standards, the PLHCP has the option of ordering additional testing 
he or she deems appropriate. Additional tests can be ordered on a 
case-by-case basis depending on individual signs or symptoms and 
clinical judgment. For example, if an

[[Page 16885]]

employee reports a history of abnormal kidney function tests, the 
PLHCP may want to order a baseline renal function tests (e.g., serum 
creatinine and urinalysis). As indicated above, the PLHCP may order 
annual TB testing for silica-exposed employees who are at high risk 
of developing active TB infections. Additional tests that PLHCPs may 
order based on findings of medical examinations include, but is not 
limited to, chest computerized tomography (CT) scan for lung cancer 
or COPD, testing for immunologic diseases, and cardiac testing for 
pulmonary-related heart disease, such as cor pulmonale.

3. Roles and Responsibilities

    3.1. PLHCP. The PLHCP designation refers to ``an individual 
whose legally permitted scope of practice (i.e., license, 
registration, or certification) allows him or her to independently 
provide or be delegated the responsibility to provide some or all of 
the particular health care services required'' by the respirable 
crystalline silica standard. The legally permitted scope of practice 
for the PLHCP is determined by each State. PLHCPs who perform 
clinical services for a silica medical surveillance program should 
have a thorough knowledge of respirable crystalline silica-related 
diseases and symptoms. Suspected cases of silicosis, advanced COPD, 
or other respiratory conditions causing impairment should be 
promptly referred to a Board Certified Specialist in Pulmonary 
Disease or Occupational Medicine.
    Once the medical surveillance examination is completed, the 
employer must ensure that the PLHCP explains to the employee the 
results of the medical examination and provides the employee with a 
written medical report within 30 days of the examination. The 
written medical report must contain a statement indicating the 
results of the medical examination, including any medical 
condition(s) that would place the employee at increased risk of 
material impairment to health from exposure to respirable 
crystalline silica and any medical conditions that require further 
evaluation or treatment. In addition, the PLHCP's written medical 
report must include any recommended limitations on the employee's 
use of respirators, any recommended limitations on the employee's 
exposure to respirable crystalline silica, and a statement that the 
employee should be examined by a Board Certified Specialist in 
Pulmonary Disease or Occupational medicine if the chest X-ray is 
classified as 1/0 or higher by the B Reader, or if referral to a 
Specialist is otherwise deemed appropriate by the PLHCP.
    The PLHCP should discuss all findings and test results and any 
recommendations regarding the employee's health, worksite safety and 
health practices, and medical referrals for further evaluation, if 
indicated. In addition, it is suggested that the PLHCP offer to 
provide the employee with a complete copy of their examination and 
test results, as some employees may want this information for their 
own records or to provide to their personal physician or a future 
PLHCP. Employees are entitled to access their medical records.
    Under the respirable crystalline silica standard, the employer 
must ensure that the PLHCP provides the employer with a written 
medical opinion within 30 days of the employee examination, and that 
the employee also gets a copy of the written medical opinion for the 
employer within 30 days. The PLHCP may choose to directly provide 
the employee a copy of the written medical opinion. This can be 
particularly helpful to employees, such as construction employees, 
who may change employers frequently. The written medical opinion can 
be used by the employee as proof of up-to-date medical surveillance. 
The following lists the elements of the written medical report for 
the employee and written medical opinion for the employer. (Sample 
forms for the written medical report for the employee, the written 
medical opinion for the employer, and the written authorization are 
provided in Section 7 of this Appendix.)
    3.1.1. The written medical report for the employee must include 
the following information:
    3.1.1.1. A statement indicating the results of the medical 
examination, including any medical condition(s) that would place the 
employee at increased risk of material impairment to health from 
exposure to respirable crystalline silica and any medical conditions 
that require further evaluation or treatment;
    3.1.1.2. Any recommended limitations upon the employee's use of 
a respirator;
    3.1.1.3. Any recommended limitations on the employee's exposure 
to respirable crystalline silica; and
    3.1.1.4. A statement that the employee should be examined by a 
Board Certified Specialist in Pulmonary Disease or Occupational 
Medicine, where the standard requires or where the PLHCP has 
determined such a referral is necessary. The standard requires 
referral to a Board Certified Specialist in Pulmonary Disease or 
Occupational Medicine for a chest X-ray B reading indicating small 
opacities in a profusion of 1/0 or higher, or if the PHLCP 
determines that referral to a Specialist is necessary for other 
silica-related findings.
    3.1.2. The PLHCP's written medical opinion for the employer must 
include only the following information:
    3.1.2.1. The date of the examination;
    3.1.2.2. A statement that the examination has met the 
requirements of this section; and
    3.1.2.3. Any recommended limitations on the employee's use of 
respirators.
    3.1.2.4. If the employee provides the PLHCP with written 
authorization, the written opinion for the employer shall also 
contain either or both of the following:
    (1) Any recommended limitations on the employee's exposure to 
respirable crystalline silica; and
    (2) A statement that the employee should be examined by a Board 
Certified Specialist in Pulmonary Disease or Occupational Medicine 
if the chest X-ray provided in accordance with this section is 
classified as 1/0 or higher by the B Reader, or if referral to a 
Specialist is otherwise deemed appropriate.
    3.1.2.5. In addition to the above referral for abnormal chest X-
ray, the PLHCP may refer an employee to a Board Certified Specialist 
in Pulmonary Disease or Occupational Medicine for other findings of 
concern during the medical surveillance examination if these 
findings are potentially related to silica exposure.
    3.1.2.6. Although the respirable crystalline silica standard 
requires the employer to ensure that the PLHCP explains the results 
of the medical examination to the employee, the standard does not 
mandate how this should be done. The written medical opinion for the 
employer could contain a statement that the PLHCP has explained the 
results of the medical examination to the employee.
    3.2. Medical Specialists. The silica standard requires that all 
employees with chest X-ray B readings of 1/0 or higher be referred 
to a Board Certified Specialist in Pulmonary Disease or Occupational 
Medicine. If the employee has given written authorization for the 
employer to be informed, then the employer shall make available a 
medical examination by a Specialist within 30 days after receiving 
the PLHCP's written medical opinion.
    3.2.1. The employer must provide the following information to 
the Board Certified Specialist in Pulmonary Disease or Occupational 
Medicine:
    3.2.1.1. A description of the employee's former, current, and 
anticipated duties as they relate to the employee's occupational 
exposure to respirable crystalline silica;
    3.2.1.2. The employee's former, current, and anticipated levels 
of occupational exposure to respirable crystalline silica;
    3.2.1.3. A description of any personal protective equipment used 
or to be used by the employee, including when and for how long the 
employee has used or will use that equipment; and
    3.2.1.4. Information from records of employment-related medical 
examinations previously provided to the employee and currently 
within the control of the employer.
    3.2.2. The PLHCP should make certain that, with written 
authorization from the employee, the Board Certified Specialist in 
Pulmonary Disease or Occupational Medicine has any other pertinent 
medical and occupational information necessary for the specialist's 
evaluation of the employee's condition.
    3.2.3. Once the Board Certified Specialist in Pulmonary Disease 
or Occupational Medicine has evaluated the employee, the employer 
must ensure that the Specialist explains to the employee the results 
of the medical examination and provides the employee with a written 
medical report within 30 days of the examination. The employer must 
also ensure that the Specialist provides the employer with a written 
medical opinion within 30 days of the employee examination. (Sample 
forms for the written medical report for the employee, the written 
medical opinion for the employer and the written authorization are 
provided in Section 7 of this Appendix.)
    3.2.4. The Specialist's written medical report for the employee 
must include the following information:
    3.2.4.1. A statement indicating the results of the medical 
examination, including any medical condition(s) that would place the 
employee at increased risk of material impairment to health from 
exposure to

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respirable crystalline silica and any medical conditions that 
require further evaluation or treatment;
    3.2.4.2. Any recommended limitations upon the employee's use of 
a respirator; and
    3.2.4.3. Any recommended limitations on the employee's exposure 
to respirable crystalline silica.
    3.2.5. The Specialist's written medical opinion for the employer 
must include the following information:
    3.2.5.1. The date of the examination; and
    3.2.5.2. Any recommended limitations on the employee's use of 
respirators.
    3.2.5.3. If the employee provides the Board Certified Specialist 
in Pulmonary Disease or Occupational Medicine with written 
authorization, the written medical opinion for the employer shall 
also contain any recommended limitations on the employee's exposure 
to respirable crystalline silica.
    3.2.5.4. Although the respirable crystalline silica standard 
requires the employer to ensure that the Board Certified Specialist 
in Pulmonary Disease or Occupational Medicine explains the results 
of the medical examination to the employee, the standard does not 
mandate how this should be done. The written medical opinion for the 
employer could contain a statement that the Specialist has explained 
the results of the medical examination to the employee.
    3.2.6. After evaluating the employee, the Board Certified 
Specialist in Pulmonary Disease or Occupational Medicine should 
provide feedback to the PLHCP as appropriate, depending on the 
reason for the referral. OSHA believes that because the PLHCP has 
the primary relationship with the employer and employee, the 
Specialist may want to communicate his or her findings to the PLHCP 
and have the PLHCP simply update the original medical report for the 
employee and medical opinion for the employer. This is permitted 
under the standard, so long as all requirements and time deadlines 
are met.
    3.3. Public Health Professionals. PLHCPs might refer employees 
or consult with public health professionals as a result of silica 
medical surveillance. For instance, if individual cases of active TB 
are identified, public health professionals from state or local 
health departments may assist in diagnosis and treatment of 
individual cases and may evaluate other potentially affected 
persons, including coworkers. Because silica-exposed employees are 
at increased risk of progression from latent to active TB, treatment 
of latent infection is recommended. The diagnosis of active TB, 
acute or accelerated silicosis, or other silica-related diseases and 
infections should serve as sentinel events suggesting high levels of 
exposure to silica and may require consultation with the appropriate 
public health agencies to investigate potentially similarly exposed 
coworkers to assess for disease clusters. These agencies include 
local or state health departments or OSHA. In addition, NIOSH can 
provide assistance upon request through their Health Hazard 
Evaluation program. (See Section 5 of this Appendix)

4. Confidentiality and Other Considerations

    The information that is provided from the PLHCP to the employee 
and employer under the medical surveillance section of OSHA's 
respirable crystalline silica standard differs from that of medical 
surveillance requirements in previous OSHA standards. The standard 
requires two separate written communications, a written medical 
report for the employee and a written medical opinion for the 
employer. The confidentiality requirements for the written medical 
opinion are more stringent than in past standards. For example, the 
information the PLHCP can (and must) include in his or her written 
medical opinion for the employer is limited to: The date of the 
examination, a statement that the examination has met the 
requirements of this section, and any recommended limitations on the 
employee's use of respirators. If the employee provides written 
authorization for the disclosure of any limitations on the 
employee's exposure to respirable crystalline silica, then the PLHCP 
can (and must) include that information in the written medical 
opinion for the employer as well. Likewise, with the employee's 
written authorization, the PLHCP can (and must) disclose the PLHCP's 
referral recommendation (if any) as part of the written medical 
opinion for the employer. However, the opinion to the employer must 
not include information regarding recommended limitations on the 
employee's exposure to respirable crystalline silica or any referral 
recommendations without the employee's written authorization.
    The standard also places limitations on the information that the 
Board Certified Specialist in Pulmonary Disease or Occupational 
Medicine can provide to the employer without the employee's written 
authorization. The Specialist's written medical opinion for the 
employer, like the PLHCP's opinion, is limited to (and must 
contain): The date of the examination and any recommended 
limitations on the employee's use of respirators. If the employee 
provides written authorization, the written medical opinion can (and 
must) also contain any limitations on the employee's exposure to 
respirable crystalline silica.
    The PLHCP should discuss the implication of signing or not 
signing the authorization with the employee (in a manner and 
language that he or she understands) so that the employee can make 
an informed decision regarding the written authorization and its 
consequences. The discussion should include the risk of ongoing 
silica exposure, personal risk factors, risk of disease progression, 
and possible health and economic consequences. For instance, written 
authorization is required for a PLHCP to advise an employer that an 
employee should be referred to a Board Certified Specialist in 
Pulmonary Disease or Occupational Medicine for evaluation of an 
abnormal chest X-ray (B-reading 1/0 or greater). If an employee does 
not sign an authorization, then the employer will not know and 
cannot facilitate the referral to a Specialist and is not required 
to pay for the Specialist's examination. In the rare case where an 
employee is diagnosed with acute or accelerated silicosis, co-
workers are likely to be at significant risk of developing those 
diseases as a result of inadequate controls in the workplace. In 
this case, the PLHCP and/or Specialist should explain this concern 
to the affected employee and make a determined effort to obtain 
written authorization from the employee so that the PLHCP and/or 
Specialist can contact the employer.
    Finally, without written authorization from the employee, the 
PLHCP and/or Board Certified Specialist in Pulmonary Disease or 
Occupational Medicine cannot provide feedback to an employer 
regarding control of workplace silica exposure, at least in relation 
to an individual employee. However, the regulation does not prohibit 
a PLHCP and/or Specialist from providing an employer with general 
recommendations regarding exposure controls and prevention programs 
in relation to silica exposure and silica-related illnesses, based 
on the information that the PLHCP receives from the employer such as 
employees' duties and exposure levels. Recommendations may include 
increased frequency of medical surveillance examinations, additional 
medical surveillance components, engineering and work practice 
controls, exposure monitoring and personal protective equipment. For 
instance, more frequent medical surveillance examinations may be a 
recommendation to employers for employees who do abrasive blasting 
with silica because of the high exposures associated with that 
operation.
    ACOEM's Code of Ethics and discussion is a good resource to 
guide PLHCPs regarding the issues discussed in this section (See 
Section 5 of this Appendix).

5. Resources

    5.1. American College of Occupational and Environmental Medicine 
(ACOEM):

ACOEM Code of Ethics. Accessed at: http://www.acoem.org/codeofconduct.aspx
Raymond, L.W. and Wintermeyer, S. (2006) ACOEM evidenced-based 
statement on medical surveillance of silica-exposed workers: Medical 
surveillance of workers exposed to crystalline silica. J Occup 
Environ Med, 48, 95-101.

    5.2. Center for Disease Control and Prevention (CDC)

Tuberculosis Web page: http://www.cdc.gov/tb/default.htm
State TB Control Offices Web page: http://www.cdc.gov/tb/links/tboffices.htm
Tuberculosis Laws and Policies Web page: http://www.cdc.gov/tb/programs/laws/default.htm
CDC. (2013). Latent Tuberculosis Infection: A Guide for Primary 
Health Care Providers. Accessed at: http://www.cdc.gov/tb/publications/ltbi/pdf/targetedltbi.pdf

    5.3. International Labour Organization

International Labour Office (ILO). (2011) Guidelines for the use of 
the ILO International Classification of Radiographs of 
Pneumoconioses, Revised edition 2011. Occupational Safety and Health 
Series No. 22: http://www.ilo.org/safework/info/publications/WCMS_168260/lang-en/index.htm

    5.4. National Institute of Occupational Safety and Health 
(NIOSH)


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NIOSH B Reader Program Web page. (Information on interpretation of 
X-rays for silicosis and a list of certified B-readers). Accessed 
at: http://www.cdc.gov/niosh/topics/chestradiography/breader-info.html
NIOSH Guideline (2011). Application of Digital Radiography for the 
Detection and Classification of Pneumoconiosis. NIOSH publication 
number 2011-198. Accessed at: http://www.cdc.gov/niosh/docs/2011-198/
NIOSH Hazard Review (2002), Health Effects of Occupational Exposure 
to Respirable Crystalline Silica. NIOSH publication number 2002-129: 
Accessed at http://www.cdc.gov/niosh/docs/2002-129/
NIOSH Health Hazard Evaluations Programs. (Information on the NIOSH 
Health Hazard Evaluation (HHE) program, how to request an HHE and 
how to look up an HHE report). Accessed at: http://www.cdc.gov/niosh/hhe/

    5.5. National Industrial Sand Association:

Occupational Health Program for Exposure to Crystalline Silica in 
the Industrial Sand Industry. National Industrial Sand Association, 
2nd ed. 2010. Can be ordered at: http://www.sand.org/silica-occupational-health-program

    5.6. Occupational Safety and Health Administration (OSHA)

Contacting OSHA: http://www.osha.gov/html/Feed_Back.html
OSHA's Clinicians Web page. (OSHA resources, regulations and links 
to help clinicians navigate OSHA's Web site and aid clinicians in 
caring for workers.) Accessed at: http://www.osha.gov/dts/oom/clinicians/index.html
OSHA's Safety and Health Topics Web page on Silica. Accessed at: 
http://www.osha.gov/dsg/topics/silicacrystalline/index.html
OSHA (2013). Spirometry Testing in Occupational Health Programs: 
Best Practices for Healthcare Professionals. (OSHA 3637-03 2013). 
Accessed at: http://www.osha.gov/Publications/OSHA3637.pdf
OSHA/NIOSH (2011). Spirometry: OSHA/NIOSH Spirometry InfoSheet (OSHA 
3415-1-11). (Provides guidance to employers). Accessed at http://www.osha.gov/Publications/osha3415.pdf
OSHA/NIOSH (2011) Spirometry: OSHA/NIOSH Spirometry Worker Info. 
(OSHA 3418-3-11). Accessed at http://www.osha.gov/Publications/osha3418.pdf

    5.7. Other

Steenland, K. and Ward E. (2014). Silica: A lung carcinogen. CA 
Cancer J Clin, 64, 63-69. (This article reviews not only silica and 
lung cancer but also all the known silica-related health effects. 
Further, the authors provide guidance to clinicians on medical 
surveillance of silica-exposed workers and worker counselling on 
safety practices to minimize silica exposure.)

6. References

American Thoracic Society (ATS). Medical Section of the American 
Lung Association (1997). Adverse effects of crystalline silica 
exposure. Am J Respir Crit Care Med, 155, 761-765.
American Thoracic Society (ATS), Centers for Disease Control (CDC), 
Infectious Diseases Society of America (IDSA) (2005). Controlling 
Tuberculosis in the United States. Morbidity and Mortality Weekly 
Report (MMWR), 54(RR12), 1-81. Accessed at: http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5412a1.htm
Brown, T. (2009). Silica exposure, smoking, silicosis and lung 
cancer--complex interactions. Occupational Medicine, 59, 89-95.
Halldin, C.N., Petsonk, E.L., and Laney, A.S. (2014). Validation of 
the International Labour Office digitized standard images for 
recognition and classification of radiographs of pneumoconiosis. 
Acad Radiol, 21, 305-311.
International Agency for Research on Cancer. (2012). Monographs on 
the evaluation of carcinogenic risks to humans: Arsenic, Metals, 
Fibers, and Dusts Silica Dust, Crystalline, in the Form of Quartz or 
Cristobalite. A Review of Human Carcinogens. Volume 100 C. Geneva, 
Switzerland: World Health Organization.
Jalloul, A.S. and Banks D.E. (2007). Chapter 23. The health effects 
of silica exposure. In: Rom, W.N. and Markowitz, S.B. (Eds). 
Environmental and Occupational Medicine, 4th edition. Lippincott, 
Williams and Wilkins, Philadelphia, 365-387.
Kramer, M.R., Blanc, P.D., Fireman, E., Amital, A., Guber, A., 
Rahman, N.A., and Shitrit, D. (2012). Artifical stone silicosis: 
Disease resurgence among artificial stone workers. Chest, 142, 419-
424.
Laney, A.S., Petsonk, E.L., and Attfield, M.D. (2011). Intramodality 
and intermodality comparisons of storage phosphor computed 
radiography and conventional film-screen radiography in the 
recognition of small pneumonconiotic opacities. Chest, 140, 1574-
1580.
Liu, Y., Steenland, K., Rong, Y., Hnizdo, E., Huang, X., Zhang, H., 
Shi, T., Sun, Y., Wu, T., and Chen, W. (2013). Exposure-response 
analysis and risk assessment for lung cancer in relationship to 
silica exposure: A 44-year cohort study of 34,018 workers. Am J Epi, 
178, 1424-1433.
Liu, Y., Rong, Y., Steenland, K., Christiani, D.C., Huang, X., Wu, 
T., and Chen, W. (2014). Long-term exposure to crystalline silica 
and risk of heart disease mortality. Epidemiology, 25, 689-696.
Mazurek, G.H., Jereb, J., Vernon, A., LoBue, P., Goldberg, S., 
Castro, K. (2010). Updated guidelines for using interferon gamma 
release assays to detect Mycobacterium tuberculosis infection--
United States. Morbidity and Mortality Weekly Report (MMWR), 
59(RR05), 1-25.
Miller, M.R., Hankinson, J., Brusasco, V., Burgos, F., Casaburi, R., 
Coates, A., Crapo, R., Enright, P., van der Grinten, C.P., 
Gustafsson, P., Jensen, R., Johnson, D.C., MacIntyre, N., McKay, R., 
Navajas, D., Pedersen, O.F., Pellegrino, R., Viegi, G., and Wanger, 
J. (2005). American Thoracic Society/European Respiratory Society 
(ATS/ERS) Task Force: Standardisation of Spirometry. Eur Respir J, 
26, 319-338.
National Toxicology Program (NTP) (2014). Report on Carcinogens, 
Thirteenth Edition. Silica, Crystalline (respirable Size). Research 
Triangle Park, NC: U.S. Department of Health and Human Services, 
Public Health Service. http://ntp.niehs.nih.gov/ntp/roc/content/profiles/silica.pdf
Occupational Safety and Health Administration/National Institute for 
Occupational Safety and Health (OSHA/NIOSH) (2012). Hazard Alert. 
Worker exposure to silica during hydraulic fracturing.
Occupational Safety and Health Administration/National Institute for 
Occupational Safety and Health (OSHA/NIOSH) (2015). Hazard alert. 
Worker exposure to silica during countertop manufacturing, 
finishing, and installation. (OSHA-HA-3768-2015).
Redlich, C.A., Tarlo, S.M., Hankinson, J.L., Townsend, M.C, 
Eschenbacher, W.L., Von Essen, S.G., Sigsgaard, T., Weissman, D.N. 
(2014). Official American Thoracic Society technical standards: 
Spirometry in the occupational setting. Am J Respir Crit Care Med; 
189, 984-994.
Rees, D. and Murray, J. (2007). Silica, silicosis and tuberculosis. 
Int J Tuberc Lung Dis, 11(5), 474-484.
Shtraichman, O., Blanc, P.D., Ollech, J.E., Fridel, L., Fuks, L., 
Fireman, E., and Kramer, M.R. (2015). Outbreak of autoimmune disease 
in silicosis linked to artificial stone. Occup Med, 65, 444-450.
Slater, M.L., Welland, G., Pai, M., Parsonnet, J., and Banaei, N. 
(2013). Challenges with QuantiFERON-TB gold assay for large-scale, 
routine screening of U.S. healthcare workers. Am J Respir Crit Care 
Med, 188,1005-1010.
Steenland, K., Mannetje, A., Boffetta, P., Stayner, L., Attfield, 
M., Chen, J., Dosemeci, M., DeKlerk, N., Hnizdo, E., Koskela, R., 
and Checkoway, H. (2001). International Agency for Research on 
Cancer. Pooled exposure-response analyses and risk assessment for 
lung cancer in 10 cohorts of silica-exposed workers: An IARC 
multicentre study. Cancer Causes Control, 12(9): 773-84.
Steenland, K. and Ward E. (2014). Silica: A lung carcinogen. CA 
Cancer J Clin, 64, 63-69.
Townsend, M.C. ACOEM Guidance Statement. (2011). Spirometry in the 
occupational health setting--2011 Update. J Occup Environ Med, 53, 
569-584.

7. Sample Forms

    Three sample forms are provided. The first is a sample written 
medical report for the employee. The second is a sample written 
medical opinion for the employer. And the third is a sample written 
authorization form that employees sign to clarify what information 
the employee is authorizing to be released to the employer.
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