

[Federal Register: January 24, 2008 (Volume 73, Number 16)]
[Proposed Rules]               
[Page 4136-4144]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr24ja08-43]                         

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2007-0995; FRL-8518-6]
RIN 2060-A073

 
Emission Standards for Stationary Diesel Engines

AGENCY: Environmental Protection Agency.

ACTION: Advance notice of proposed rulemaking.

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SUMMARY: With this advance notice of proposed rulemaking, the U.S. 
Environmental Protection Agency is soliciting comment on several issues 
concerning options the U.S. Environmental Protection Agency can pursue 
through Federal rulemaking under the Clean Air Act to regulate 
emissions of pollutants from existing stationary diesel engines, 
generally, and specifically from larger, older stationary diesel 
engines. The U.S. Environmental Protection Agency has taken several 
actions over the past several years to reduce exhaust pollutants from 
stationary diesel engines. The Agency continues to be interested in 
exploring opportunities to further reduce exhaust pollutants from 
stationary diesel engines, particularly existing stationary diesel 
engines that have not been subject to federal standards. This advance 
notice of proposed rulemaking is intended to explore possible options 
to achieve further emissions reductions, particularly from existing 
stationary diesel engines.

DATES: Comments must be received on or before February 25, 2008.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2007-0995, by one of the following methods:
     http://www.regulations.gov: Follow the on-line instructions for 

submitting comments.
     E-mail: a-and-r-Docket@epa.gov.
     Fax: (202) 566-9744.
     Mail: U.S. Postal Service, send comments to: Emissions 
Standards for Stationary Diesel Engines Docket, Environmental 
Protection Agency, Air and Radiation Docket and Information Center, 
Mailcode: 2822T, 1200 Pennsylvania Avenue, NW., Washington, DC 20460. 
Please include a total of two copies. We request that a separate copy 
also be sent to the contact person identified below (see FOR FURTHER 
INFORMATION CONTACT).
    Hand Delivery: In person or by courier, deliver comments to: EPA 
Docket and Information Center, Public Reading Room, EPA West Building, 
Room 3334, 1301 Constitution Avenue, NW., Washington, DC 20004. Such 
deliveries are only accepted during the Docket's normal hours of 
operation, and special arrangements should be made for deliveries of 
boxed information.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2007-0995. The U.S. Environmental Protection Agency's (EPA's) policy is 
that all comments received will be included in the public docket 
without change and may be made available online at http://www.regulations.gov,


[[Page 4137]]

including any personal information provided, unless the comment 
includes information claimed to be Confidential Business Information 
(CBI) or other information whose disclosure is restricted by statute. 
Do not submit information that you consider to be CBI or otherwise 
protected through http://www.regulations.gov or e-mail. The 

http://www.regulations.gov Web site is an ``anonymous access'' system, which 

means EPA will not know your identity or contact information unless you 
provide it in the body of your comment. If you send an e-mail comment 
directly to EPA without going through http://www.regulations.gov, your e-mail 

address will be automatically captured and included as part of the 
comment that is placed in the public docket and made available on the 
Internet. If you submit an electronic comment, EPA recommends that you 
include your name and other contact information in the body of your 
comment and with any disk or CD-ROM you submit. If EPA cannot read your 
comment due to technical difficulties and cannot contact you for 
clarification, EPA may not be able to consider your comment. Electronic 
files should avoid the use of special characters, any form of 
encryption, and be free of any defects or viruses. For additional 
information about EPA's public docket visit the EPA Docket Center 
homepage at http://www.epa.gov/epahome/dockets.htm.

    Docket: All documents in the docket are listed in the 
http://www.regulations.gov index. Although listed in the index, some 

information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, will be publicly available only in hard copy. 
Publicly available docket materials are available either electronically 
in http://www.regulations.gov or in hard copy at the Emissions Standards for 

Stationary Diesel Engines Docket, Environmental Protection Agency, EPA 
West Building, Room 3334, 1301 Constitution Ave., NW., Washington, DC. 
The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday 
through Friday, excluding legal holidays. The telephone number for the 
Public Reading Room is (202) 566-1744, and the telephone number for the 
Air and Radiation Docket is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: Mr. Christopher S. Stoneman, Outreach 
and Information Division, Office of Air Quality Planning and Standards, 
Mail Code C304-01, Environmental Protection Agency, Research Triangle 
Park, NC 27711, telephone number: (919) 541-0823, fax number: (919) 
541-0072; e-mail address: stoneman.chris@epa.gov.

SUPPLEMENTARY INFORMATION: 

I. General Information
    A. Does this action apply to me?
    B. What should I consider as I prepare my comments for EPA?
    1. Submitting CBI.
    2. Tips for Preparing Your Comments.
    C. Where can I get a copy of this document and other related 
information?
II. Background Information
    A. What is the purpose of this action?
    B. Why are emissions from diesel engines a health concern?
    C. What is the Agency already doing to address diesel emissions 
from new and existing stationary and mobile diesel engines?
    D. What do we know about existing stationary diesel engines?
III. Specific Issues on Which EPA is Seeking Comment
    A. What particular subgroups of existing stationary diesel 
engines should EPA focus on and how can EPA best find information on 
those engines?
    B. Where can EPA find better information about the location and 
numbers of existing stationary engines, who owns and operates them 
and what impact they are having (including hours of operation)?
    C. What are appropriate and available technically-feasible, 
cost-effective methods of controlling emissions from existing 
stationary diesel engines?
    D. To what degree do state and local governments regulate 
emissions from stationary diesel engines?
    E. What are appropriate methods of ensuring compliance with such 
requirements, including record-keeping and testing issues?
IV. How EPA Intends to Proceed Following Publication of This Notice
V. Statutory and Executive Order Reviews

I. General Information

A. Does this action apply to me?

    This notice is likely to be of interest to a variety of parties, 
including owners and operators of stationary diesel engines, 
manufacturers of stationary diesel engines, state and local air quality 
agencies responsible for developing diesel pollution reduction 
strategies, and individuals and organizations with an interest in 
emissions from diesel engines. All of these parties and others 
interested in stationary diesel engine issues are encouraged to read 
this notice and to submit comments for EPA's consideration.

B. What should I consider as I prepare my comments for EPA?

    1. Submitting CBI. Do not submit this information to EPA through 
http://www.regulations.gov or e-mail. Clearly mark the part or all of the 

information that you claim to be CBI. For CBI information in a disk or 
CD-ROM that you mail to EPA, mark the outside of the disk or CD-ROM as 
CBI and then identify electronically within the disk or CD-ROM the 
specific information that is claimed as CBI. In addition to one 
complete version of the comment that includes information claimed as 
CBI, a copy of the comment that does not contain the information 
claimed as CBI must be submitted for inclusion in the public docket. 
Information so marked will not be disclosed except in accordance with 
procedures set forth in 40 CFR part 2.
    2. Tips for Preparing Your Comments. When submitting comments, 
remember to:
     Identify the rulemaking by docket number and other 
identifying information (subject heading, Federal Register date and 
page number).
     Follow directions--The Agency may ask you to respond to 
specific questions or organize comments by referencing a Code of 
Federal Regulations (CFR) part or section number.
     Explain why you agree or disagree, suggest alternatives, 
and substitute language for your requested changes.
     Describe any assumptions and provide any technical 
information and/or data that you used.
     If you estimate potential costs or burdens, explain how 
you arrived at your estimate in sufficient detail to allow for it to be 
reproduced.
     Provide specific examples to illustrate your concerns, and 
suggest alternatives.
     Explain your views as clearly as possible, avoiding the 
use of profanity or personal threats.
     Make sure to submit your comments by the comment period 
deadline identified.

C. Where can I get a copy of this document and other related 
information?

    In addition to being available in the docket, an electronic copy of 
this notice will be available on the Worldwide Web through the 
Technology Transfer Network (TTN). The TTN provides information and 
technology exchange in various areas of air pollution control. 
Following signature, an electronic version of this document will be 
posted at http://www.epa.gov/ttn/oarpg under ``Recent Additions.''


II. Background Information

A. What is the purpose of this action?

    The EPA has taken several actions over the past few years to reduce

[[Page 4138]]

exhaust pollutants (e.g., particulate matter (PM), nitrogen oxides 
(NOX), hazardous air pollutants (HAPs)) from mobile and 
stationary diesel engines as these pollutants have been associated with 
several health-related concerns, including cancer, respiratory 
problems, and premature death. Diesel exhaust is a complex mixture of 
hundreds of constituents in either a gas or particle form resulting 
from the complete and incomplete combustion of fuel and small amounts 
of engine oil. While EPA uses the term ``diesel exhaust'' as a static 
concept throughout this document, EPA recognizes that the mixture of 
chemicals in diesel engine exhaust can vary in important ways, 
particularly when comparing exhaust from uncontrolled engines to 
exhaust from controlled engines.\1\ Diesel exhaust varies significantly 
in chemical composition and particle sizes between different engine 
types (heavy-duty, light-duty), engine operating conditions (e.g., 
idle, acceleration, deceleration) and fuel formulations (high/low 
sulfur). Over 600 compounds or elements have been identified in diesel 
exhaust.\2\ The emissions include particles composed of carbon and/or 
inorganic constituents with organics, trace elements and ions absorbed 
onto the particles, and organic and inorganic gases. The PM present in 
diesel exhaust consists primarily of fine particles (generally 
referring to particles less than or equal to 2.5 micrometers ([mu]m) in 
diameter), including a subgroup with a large number of ultrafine 
particles (generally referring to particles less than 0.1 [mu]m in 
diameter). Collectively, these particles have a large surface area 
which makes them effective for absorbing organic and inorganic HAPs. 
Their small size also makes them highly respirable and able to reach 
deeply into the lungs.\3\
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    \1\ While the EPA Diesel Health Assessment Document refers to 
``diesel exhaust'' in general, it also notes that the ``health 
hazard conclusions are based on exhaust emissions from diesel 
engines built prior to the mid-1990s. * * * As new and cleaner 
diesel engines, together with different diesel fuels, replace a 
substantial number of existing engines, the general applicability of 
the health hazard conclusions will need to be reevaluated.,'' 
``Health Assessment Document for Diesel Engine Exhaust,'' U.S. 
Environmental Protection Agency, 600/8-90/057F, http://www.epa.gov/ttn/atw/dieselfinal.pdf
, May 2002, p. 1-3.

    \2\ ``Expanding and Updating the Master List of Compounds 
Emitted by Mobile Sources--Phase III Final Report,'' U.S. 
Environmental Protection Agency, EPA420-R-06-005, http://www.epa.gov/otaq/regs/toxics/420r06005.pdf
, February 2006.

    \3\ ``Air Quality Criteria for Particulate Matter,'' U.S. 
Environmental Protection Agency, Volume II Document No. EPA600/P-99/
002bF, October 2004, Chapter 6.
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    As discussed below, EPA has already taken several actions to reduce 
pollution from diesel engines. In combination, these efforts will 
improve air quality by substantially reducing emissions of pollutants 
from these engines. However, the Agency continues to be interested in 
exploring further opportunities to reduce exhaust pollutants from 
diesel engines generally, and specifically from larger, older 
stationary diesel engines, the subject of this notice.
    Some stakeholders are encouraging the Agency to review whether 
there are further ways to reduce emissions of pollutants from existing 
stationary diesel engines. In its comments on EPA's 2006 proposed rule 
for new stationary diesel engines,\4\ Environmental Defense suggested 
several possible avenues for the regulation of existing stationary 
diesel engines, including use of diesel oxidation catalysts or 
catalyzed diesel particulate filters, as well as the use of ultra-low 
sulfur diesel (ULSD) fuel. Environmental Defense suggested that such 
controls can provide significant pollution reductions at reasonable 
cost.
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    \4\ ``Standards of Performance for Stationary Spark Ignition 
Internal Combustion Engines and National Emission Standards for 
Hazardous Air Pollution for Reciprocating Internal Combustion 
Engines,'' 71 FR 33803-33855, http://www.epa.gov/ttn/atw/rice/ricepg.html, 

June 12, 2006.
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    As a result of discussions with Environmental Defense and other 
interested stakeholders, EPA is undertaking this Advance Notice of 
Proposed Rulemaking (ANPR). The purpose of this action is to solicit 
comment and collect information to aid decision-making related to the 
reduction of HAP emissions from existing stationary diesel engines and 
specifically from larger, older engines under Clean Air Act (CAA) 
section 112 authorities.\5\ The Agency is seeking comment on the 
larger, older engines because available data indicate that they emit 
the majority of PM and toxic emissions from non-emergency stationary 
engines as a whole.
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    \5\ If reductions in HAP emissions occur in the future through 
the issuance of EPA regulation, because some HAPs are in the 
particulate form, a reduction in HAP emissions may also result in 
reductions of emissions of particulate matter.
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    The EPA requests comment on specific, well supported information 
that will assist the Agency with moving forward with the regulation of 
existing stationary diesel engines (Section III). The areas for which 
EPA is seeking comment include:
     Locations of stationary diesel engines;
     Usage and duty cycles;
     Technical parameters that help define ``older'' engines 
for purposes of defining potential subcategories of engines;
     Which stationary diesel engines to control;
     Appropriate controls for those engines;
     Existing stationary engine control measures in place, 
including State and local requirements;
     Costs and cost effectiveness of, and emission reductions 
associated with, different control technologies and control strategies; 
and
     Monitoring, recordkeeping and reporting requirements for 
owners and operators of existing stationary engines subject to 
emissions standards.
    In this ANPR, EPA provides background information on:
     Existing and other proposed efforts to control stationary 
engine emissions;
     Some of the information we have on existing stationary 
diesel engines; and
     Health concerns related to emissions from diesel engines.

B. Why are emissions from diesel engines a health concern?

    EPA published a Diesel Health Assessment Document (Diesel HAD) in 
September 2002.\6\ Some of the HAD's important results are summarized 
here. The Diesel HAD classified exposure to diesel exhaust as ``likely 
to be carcinogenic to humans by inhalation'' at environmental levels of 
exposure. Other agencies at the international, federal and state level 
have come to similar conclusions.\7\ The EPA Diesel HAD provided 
insight into the possible ranges of lung cancer risk that might be 
present in the population resulting from environmental exposure to 
diesel emissions. Lifetime cancer risk may exceed 10-5 and 
could be as high as 10-3. Because of uncertainties, the 
analysis acknowledged that the risks could be lower than 
10-4 or 10-5, and a zero risk from diesel exhaust 
exposure was not ruled out. This range of values includes numerous 
uncertainties and, as discussed in the Diesel HAD, does not constitute 
an Agency cancer unit risk range suitable for estimating the number of 
cancer cases resulting from exposure to diesel exhaust. EPA's 1999 
National-Scale Air Toxics Assessment (NATA) does not include a 
quantitative estimate of cancer risk for diesel exhaust, but it 
concludes that diesel exhaust ranks with the other emissions that the

[[Page 4139]]

national-scale assessment suggests pose the greatest relative risk.\8\ 
The purpose of this national-scale assessment is to provide a 
perspective on the magnitude of risks posed by outdoor sources of air 
toxics and to identify the pollutants and sources that are important 
contributors to these health risks.
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    \6\ Health Assessment Document for Diesel Engine Exhaust,'' U.S. 
Environmental Protection Agency, 600/8-90/057F, http://www.epa.gov/ttn/atw/dieselfinal.pdf
, May 2002.

    \7\ A [0] number of other agencies (National Institute for 
Occupational Safety and Health, the International Agency for 
Research on Cancer, the World Health Organization, California EPA, 
and the U.S. Department of Health and Human Services) have made 
similar classifications regarding the diesel exhaust lung cancer 
hazard.
    \8\ For more information on NATA, see http://www.epa.gov/ttn/atw/nata1999/risksum.html
.

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    The Diesel HAD established an inhalation Reference Concentration 
(RfC) of 5 [mu]g/m\3\ for diesel exhaust as measured by diesel PM.\9\ 
The Diesel HAD concludes ``that acute exposure to DE [diesel exhaust] 
has been associated with irritation of the eye, nose, and throat, 
respiratory symptoms (cough and phlegm), and neurophysiological 
symptoms such as headache, lightheadedness, nausea, vomiting, and 
numbness or tingling of the extremities.'' \10\ There is also evidence 
of immunologic effects such as the exacerbation of allergenic responses 
to known allergens and asthma-like symptoms.
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    \9\ An RfC is defined by EPA as ``an estimate of a continuous 
inhalation exposure to the human population, including sensitive 
subgroups, with uncertainty spanning perhaps an order of magnitude, 
which is likely to be without appreciable risks of deleterious 
noncancer effects during a lifetime.''
    \10\ ``Health Assessment Document for Diesel Engine Exhaust,'' 
U.S. Environmental Protection Agency, 600/8-90/057F, http://www.epa.gov/ttn/atw/dieselfinal.pdf
, May 2002, p. 9-9.

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    Diesel exhaust is a mixture that includes HAPs that are known or 
suspected human carcinogens or have noncancer effects, including 
benzene, 1,3-butadiene, formaldehyde, acetaldehyde, polycyclic organic 
matter (POM), and naphthalene. Benzene\11\ and 1,3-butadiene\12\ are 
known human carcinogens. Noncancer health effects may include 
neurological, cardiovascular, liver, kidney, and respiratory effects, 
as well as effects on the immune and reproductive systems.
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    \11\ Integrated Risk Information System File for Benzene, U.S. 
Environmental Protection Agency, http://www.epa.gov/ncea/iris/subst/0276.htm
, 2000.

    \12\ Integrated Risk Information System File for 1,3-Butadiene, 
U.S. Environmental Protection Agency, http://www.epa.gov/ncea/iris/subst/0139.htm
, 2002.

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    Several of the HAPs emitted by diesel engines (e.g., acrolein, 
benzene, 1,3-butadiene, formaldehyde, naphthalene, and POM) were 
identified in EPA's 1999 NATA as national or regional cancer and/or 
noncancer risk drivers.\13\ However, EPA does not have high confidence 
in the NATA data for all these compounds.\14\ It should be noted that 
the NATA modeling framework has a number of limitations which prevent 
its use as the sole basis for setting regulatory standards. These 
limitations and uncertainties are discussed on the 1999 NATA Web site. 
Even so, this modeling framework is very useful in identifying air 
toxic pollutants and sources of greatest concern, setting regulatory 
priorities, and informing the decision making process.\15\
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    \13\ More information on NATA risk drivers is available at: 
http://www.epa.gov/ttn/atw/nata1999/risksum.html.

    \14\ See ``Control of Emissions From New Marine Compression-
Ignition Engines at or Above 30 Liters per Cylinder; Proposed 
Rule,'' 72 FR 69521-69552, 69534, http://www.epa.gov/fedrgstr/EPA-AIR/2007/December/Day-07/a23556.htm
, December 2007.

    \15\ For more information on NATA, see http://www.epa.gov/ttn/atw/nata1999/risksum.html
.

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    Diesel emissions contain fine and ultra-fine PM and contribute 
significantly to ambient PM2.5 concentrations in many areas 
of the country.\16\ The nature of the effects that have been reported 
to be associated with fine particle exposures include premature 
mortality, aggravation of respiratory and cardiovascular disease (as 
indicated by increased hospital admissions and emergency department 
visits), changes in lung function and increased respiratory symptoms, 
as well as new evidence for more subtle indicators of cardiovascular 
health (71 FR 61152, October 17, 2006).\17\ The PM Air Quality Criteria 
Document also notes that the PM components of gasoline and diesel 
engine exhaust represent one class of hypothesized likely important 
contributors to the observed ambient PM-related increases in lung 
cancer incidence and mortality.\18\ The PM2.5 National 
Ambient Air Quality Standard is designed to provide protection from the 
noncancer and premature mortality effects of PM2.5 as a 
whole, of which diesel PM is a constituent.\19\
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    \16\ ``Health Assessment Document for Diesel Engine Exhaust,'' 
U.S. Environmental Protection Agency, 600/8-90/057F, http://www.epa.gov/ttn/atw/dieselfinal.pdf
, May 2002, p. 2-97, Table 2-23.

    \17\ Detailed information on the health effects of PM is 
provided in: ``Air Quality Criteria for Particulate Matter,'' U.S. 
Environmental Protection Agency, Volume I, EPA600/P-99/002aF and 
Volume II, EPA600/P-99/002bF, October 2004; ``Review of the National 
Ambient Air Quality Standard for Particulate Matter: Policy 
Assessment of Scientific and Technical Information, OAQPS Staff 
Paper,'' U.S. Environmental Protection Agency, EPA-452/R-05-005, 
2005; ``National Ambient Air Quality Standards for Particulate 
Matter; Proposed Rule,'' 71 FR 2620-2708, 2626-2637, http://www.epa.gov/air/particlepollution/actions.html
, January 17, 2006 and 

``National Ambient Air Quality Standards for Particulate Matter; 
Final Rule,'' 71 FR 61144-61233, http://www.epa.gov/air/particlepollution/actions.html
, October 17, 2006.

    \18\ ``Air Quality Criteria for Particulate Matter,'' U.S. 
Environmental Protection Agency, Volume I, EPA600/P-99/002aF and 
Volume II, EPA600/P-99/002bF, October 2004, p. 8-318.
    \19\ ``Control of Emissions of Air Pollution From Locomotive 
Engines and Marine Compression-Ignition Engines Less Than 30 Liters 
per Cylinder; Proposed Rule,'' 72 FR 15937-15986, 15958, http://www.epa.gov/oms/locomotv.htm
, April 3, 2007.

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    Diesel exhaust also includes NOX and volatile organic 
compounds, which react in the presence of sunlight to form ozone. Ozone 
contributes to serious public health problems, including aggravation of 
respiratory disease (as indicated by increased hospital admissions and 
emergency room visits, school absences, lost work days, and restricted 
activity days), changes in lung function and increased respiratory 
symptoms, altered respiratory defense mechanisms, and chronic 
bronchitis. In addition, there is suggestive evidence of a contribution 
of ozone to cardiovascular-related morbidity and highly suggestive 
evidence that short-term ozone exposure directly or indirectly 
contributes to non-accidental and cardiopulmonary-related mortality, 
but additional research is needed to more fully establish underlying 
mechanisms by which such effects occur.\20\
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    \20\ Detailed information regarding the health effects of 
ozone[0] is provided in: ``Air Quality Criteria for Ozone and 
Related Photochemical Oxidants (Final),'' U.S. Environmental 
Protection Agency, EPA/600/R-05/004aF-cF, 2006, pp. 7-97 and 8-78; 
``Review of the National Ambient Air Quality Standards for Ozone: 
Policy Assessment of Scientific and Technical Information, OAQPS 
Staff Paper,'' U.S. Environmental Protection Agency, EPA-452/R-07-
003, January 2007; and ``National Ambient Air Quality Standards for 
Ozone: Proposed Rule,'' 72 FR 37818-37919, 37844 and 37836, http://www.epa.gov/air/ozonepollution/actions.html
, July 11, 2007.

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    Tables 3 and 4 in the Section II.D. below indicate that older, 
larger non-emergency stationary source diesel engines generate a 
substantial share of the emissions from all stationary diesel engines. 
In this context, it is important to consider the health effects 
associated with diesel exhaust.

C. What is the Agency already doing to address diesel emissions from 
new and existing stationary and mobile diesel engines?

    EPA has undertaken several specific regulatory efforts to control 
emissions from new or reconstructed stationary diesel engines. In June 
2004, EPA published national emission standards for hazardous air 
pollutants (NESHAP) for stationary reciprocating internal combustion 
engines (RICE) \21\ with a site rating of greater than 500 brake horse 
power (BHP) located at major sources.\22\

[[Page 4140]]

The rule contains emission limitations for new and reconstructed 
compression ignition (i.e. diesel) stationary RICE, among other 
sources. In that action, EPA identified stationary RICE as major 
sources of HAP emissions, such as formaldehyde, acrolein, methanol, and 
acetaldehyde. The NESHAP required all RICE above 500 BHP located at 
major sources to meet HAP emission standards reflecting the application 
of the maximum achievable control technology (MACT). EPA estimated at 
the time that 40% of stationary RICE would be located at major sources 
and thus, subject to the final rule. New or reconstructed stationary 
RICE that operate exclusively as emergency or limited use units were 
subject only to initial notification requirements. The RICE rule is 
projected to reduce total national HAP emissions by an estimated 5,600 
tons per year (tpy) in the 5th year after the rule is promulgated. EPA 
expects that engine manufacturers will achieve the expected reductions 
by installing diesel oxidation catalysts. The emissions reduction 
performance provided by the installation of diesel oxidation catalysts 
through this rule were projected to reduce PM emissions from the 
affected engines by 20-30%, compared with uncontrolled engines.
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    \21\ A reciprocating engine is an internal combustion engine 
that uses reciprocating motion to convert heat energy into 
mechanical work.
    \22\ ``National Emission Standards for Hazardous Air Pollutants 
for Stationary Reciprocating Internal Combustion Engines,'' 69 FR 
33474-33522, http://www.epa.gov/ttn/atw/rice/ricepg.html, June 15, 2004.

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    In July 2006, EPA published new source performance standards (NSPS) 
for new stationary compression ignition (CI) internal combustion 
engines (ICE).23 24 The standards implement section 111(b) 
of the CAA and are based on the Administrator's determination that 
stationary CI ICE cause, or contribute significantly to, air pollution 
that may reasonably be anticipated to endanger public health or 
welfare. The standards require all new, modified, and reconstructed 
stationary CI ICE to use the best demonstrated system of continuous 
emission reduction of PM, NOX, hydrocarbons and CO 
considering costs, non-air quality health, and environmental and energy 
impacts. The CI ICE NSPS affects stationary CI ICE that commenced 
construction, modification or reconstruction after July 11, 2005. EPA 
generally requires that engines affected by the rulemaking use ULSD 
\25\ for all engines (emergency and non-emergency). EPA expects that 
non-emergency engines will need to use diesel particulate filters and 
NOX aftertreatment to meet the NSPS. The final standards 
will reduce NOX by an estimated 38,000 tpy, PM by an 
estimated 3,000 tpy, sulfur dioxide by an estimated 9,000 tpy, 
nonmethane hydrocarbons by an estimated 600 tpy, and CO by an estimated 
18,000 tpy in the year 2015.
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    \23\ ``Standards of Performance for Stationary Compression 
Ignition Internal Combustion Engines; Final Rule,'' 71 FR 39153-
39185, http://www.epa.gov/fedrgstr/EPA-AIR/2006/July/Day-11/a5968.htm, July 

11, 2006.
    \24\ Similar to the diesel engines covered by the RICE rule, 
these compression ignition, internal combustion engines are also 
reciprocating, diesel engines. However, the 2006 NSPS rulemaking 
covered fewer types of engines and different pollutants than the 
June 2004 RICE rule. The 2006 rulemaking addressed criteria 
pollutants from compression ignition engines, while the 2004 RICE 
rule addressed HAP emissions from both compression-ignition and 
spark-ignition engines, both of which are reciprocating engines. For 
that reason, the 2004 engine rule refers to the engines it covers as 
``RICE'' rather than the narrower term used to describe the engines 
covered by the 2006 engine rule: CI ICE.
    \25\ EPA also requires ULSD for nonroad and on-highway engines 
that should help ensure widespread availability of the fuel for 
stationary engines. See ``Control of Air Pollution from New Motor 
Vehicles: Heavy-Duty Engine and Vehicle Standards and Highway Diesel 
Fuel Sulfur Control Requirements,'' 66 FR 5001-5193, http://www.epa.gov/otaq/highway-diesel/regs/2007-heavy-duty-highway.htm
, January 2001 

and ``Control of Emissions of Air Pollution From Nonroad Diesel 
Engines and Fuel,'' 69 FR 38957-39273, http://www.epa.gov/nonroad-diesel/2004fr.htm
, June 29, 2004.

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    In June 2006, EPA published a proposed NESHAP for stationary RICE 
that either are located at area sources of HAP emissions or that have a 
site rating of less than or equal to 500 BHP and are located at major 
sources of HAP emissions.\26\ In that same action, EPA also proposed 
NSPS for stationary spark ignition internal combustion engines. In 
December 2007, EPA finalized the NSPS for spark ignition engines and 
the NESHAP for new stationary RICE sources. EPA will be issuing a 
proposed NESHAP for existing engines in 2009.
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    \26\ ``Standards of Performance for Stationary Spark Ignition 
Internal Combustion Engines and National Emission Standards for 
Hazardous Air Pollution for Reciprocating Internal Combustion 
Engines,'' 71 FR 33803-33855, http://www.epa.gov/ttn/atw/rice/ricepg.html, 

June 12, 2006.
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    For new mobile source diesel engines, EPA has issued the Heavy-Duty 
Highway Diesel Engine and Fuel Rule \27\ and the Clean Air Nonroad 
Diesel Engine and Fuel Rule \28\ regulatory programs. Overall, the 
substantial majority of diesel exhaust is emitted from mobile sources 
rather than stationary sources. Engines meeting the emission standards 
required by the Heavy-Duty Highway Diesel Engine and Fuel Rule achieve 
a greater than 98 percent reduction in PM and NOX over 
uncontrolled emission levels. This program, when fully phased in, will 
provide annual emission reductions equivalent to removing the pollution 
from more than 90 percent of today's trucks and buses, or about 13 
million trucks and buses. We project that in 2030, when the current 
heavy-duty vehicle fleet is completely replaced with newer heavy-duty 
vehicles that comply with these emission standards, this program will 
reduce annual emissions of non-methane hydrocarbons by 115,000 tons, PM 
by 109,000 tons, and NOX by 2.6 million tons. Similarly, the 
nonroad program will reduce NOX and PM emissions from 
nonroad diesel engines by more than 90 percent. Both rules will provide 
a wide range of public health benefits. Additionally, EPA has recently 
proposed regulations for locomotive and marine engines. These 
regulatory programs will ultimately yield reductions of PM and 
NOX from mobile sources as high as 90%, depending upon 
engine category.
---------------------------------------------------------------------------

    \27\ See ``Control of Air Pollution from New Motor Vehicles: 
Heavy-Duty Engine and Vehicle Standards and Highway Diesel Fuel 
Sulfur Control Requirements,'' 66 FR 5001-5193, http://www.epa.gov/otaq/highway-diesel/regs/2007-heavy-duty-highway.htm
, January 2001.

    \28\ See ``Control of Emissions of Air Pollution From Nonroad 
Diesel Engines and Fuel,'' 69 FR 38957-39273, http://www.epa.gov/nonroad-diesel/2004fr.htm
, June 29, 2004.

---------------------------------------------------------------------------

    EPA has also developed the National Clean Diesel Campaign, which 
aims to reduce emissions from existing mobile source diesel engines 
through innovative retrofit programs. Through the campaign, as of 2005 
more than 300 clean diesel projects nationwide are resulting in 
significant emission reductions (in lifetime tons) including: 110,000 
NOX, 20,000 PM, 35,000 hydrocarbons and 25,000 carbon 
monoxide (CO).\29\ To date, emissions from more than 200,000 diesel 
vehicles have been reduced through these projects.
---------------------------------------------------------------------------

    \29\ For more information, see ``National Clean Diesel Campaign: 
Innovative Strategies for Cleaner Air, 2005 Progress Report,'' U.S. 
Environmental Protection Agency, EPA420-R-06-009, http://www.epa.gov/cleandiesel/documents/420r06009.pdf
, June 2006.

---------------------------------------------------------------------------

    In addition to these rulemakings, EPA is reviewing its ability to 
take certain steps to further encourage emission reductions from 
existing diesel engines, including:
    1. Publishing a control techniques guideline/alternative control 
technology document for existing stationary diesel engines;
    2. Developing guidance pertaining to EPA review of federal actions 
under the National Environmental Policy Act and CAA section 309 
addressing the characterization and mitigation of emissions from new 
and existing diesel engines;
    3. Encouraging emission controls for existing stationary diesel 
engines through voluntary programs;
    4. Exploring methods of promoting the use of clean diesel engines 
by entities in the federal government; and

[[Page 4141]]

    5. Publishing a white paper together with an analytical tool for 
local areas and states to estimate health benefits of diesel emissions 
reduction strategies.
    In addition, EPA, among others, is helping to fund the study of 
differences in the health effects associated with PM from cleaner 
burning diesel engines.

D. What do we know about existing stationary diesel engines?

    EPA's knowledge about the types of and use of stationary diesel 
engines consists primarily of certain general information. Based on the 
number of hours of operation, existing stationary diesel engines are 
considered either non-emergency or emergency. Generally, non-emergency 
engines operate about 1,000 hours per year, though they can run more or 
less than that. Non-emergency engines are engines that are used for 
several purposes or applications such as: oil and gas industry, 
including oil and gas extraction and transmission; agriculture (e.g., 
irrigation pumps); and generation of electricity in remote areas or for 
purposes of meeting peak demand. Emergency engines operate on an 
emergency or as-needed basis, including periodically for short periods 
of time for testing purposes to ensure engine performance in the event 
of an emergency. Applications for emergency engines include electric 
power for emergency commercial and institutional needs. For example, 
hospitals and any other facilities that require power in the event of a 
power outage may use emergency engines. Emergency engines typically 
operate an average of 50 hours per year.
    Based on (1) sales information from diesel engine manufacturers, 
(2) data from the Power Systems Research Database and (3) estimates of 
the stationary source fraction of the total engine sales, EPA estimates 
that there are about 900,000 existing stationary compression ignition 
(CI) or diesel engines in the U.S. (see Table 1). About 20% of the 
engines (about 180,000) are considered non-emergency and about 80% are 
considered emergency (about 720,000).
    Generally, diesel emissions from the engines reflected in Table 1 
(and the other Tables in this notice) are largely uncontrolled at the 
Federal level as EPA's emissions standards for stationary diesel 
engines did not take effect until August 2004. Non-emergency engines 
are estimated to emit 90% of total combined PM and NOX 
emissions from all stationary diesel engines, while emergency engines 
are estimated to emit 10% of total PM and NOX emissions. 
Based on this information, we believe that a relatively small 
percentage of the total number of stationary diesel engines operating 
in the United States are emitting a significant amount of the HAPs from 
stationary diesel engines overall.
    Of the non-emergency engines, about 36,000 non-emergency engines 
rated 300 BHP or higher were built prior to 1996, which is about 21% of 
all non-emergency engines (see Table 2). These 36,000 engines emit 
about:
     57% of the total PM emissions from all stationary non-
emergency diesel engines (see Table 3); and
     59% of the total HAP emissions from all stationary non-
emergency diesel engines (see Table 4).

      Table 1.--Engine Manufacturers Association Estimates of Stationary Diesel Engines in Use in the U.S.
----------------------------------------------------------------------------------------------------------------
        Engine ratings             <  1980       1980-1994     1995-2001     2002-2005      Totals      Percent
----------------------------------------------------------------------------------------------------------------
>=50 and <100 BHP.............      26,200        62,759        49,919        22,521        161,399         17.9
>=100 and <175 BHP............      57,426        92,857        61,572        23,634        235,489         26.1
>=175 and <300 BHP............      27,198        63,991        57,739        40,877        189,805         21.1
>=300 and <600 BHP............      70,303        53,188        38,778        31,403        193,672         21.5
>=600 and <750 BHP............       8,562        12,664        10,743         8,648         40,617          4.5
>=750.........................       6,899        28,357        33,835        10,520         79,611          8.8
                               ---------------------------------------------------------------------------------
    Totals....................     196,588       313,816       252,586       137,603        900,593         99.9
    Percent...................          21.8          34.8          28.0          15.3  ...........  ...........
----------------------------------------------------------------------------------------------------------------
Notes:
 The Engine Manufacturers Association engine sales data that was used to help develop these numbers
  represent 70% of total U.S. engine sales.
 Assumes all 1999-2005 engines are currently in operation.
 Total percent does not equal 100 due to rounding.
Source: Engine Manufacturers Association.


  Table 2.--Engine Manufacturers Association Estimates of Non-Emergency Stationary Diesel Engines in Use in the
                                                      U.S.
----------------------------------------------------------------------------------------------------------------
          Engine ratings               <  1980     1980-1995    1996-2001    2002-2005      Totals      Percent
----------------------------------------------------------------------------------------------------------------
>=50 and <100 BHP.................        4,978       14,145        7,264        4,279       30,666         17.9
>=100 and <175 BHP................       10,911       21,163        8,179        4,490       44,743         26.1
>=175 and <300 BHP................        5,168       14,700        8,429        7,767       36,064         21.1
>=300 and <600 BHP................       13,358       11,217        6,256        5,967       36,798         21.5
>=600 and <750 BHP................        1,627        2,644        1,804        1,643        7,718          4.5
>=750.............................        1,311        6,212        5,605        1,999       15,127          8.8
                                   -----------------------------------------------------------------------------
    Totals........................       37,353       70,081       37,537       26,145      171,116        100.0
----------------------------------------------------------------------------------------------------------------
               Engines  300 BHP and < 1996: 36,369 (21.3 of all non-emergency engines)
----------------------------------------------------------------------------------------------------------------
Notes:
 EPA is providing the 36,369 engine number because we are considering focusing for regulation on non-
  emergency diesel engines that were built before 1996 and that are rated greater than 300 BHP, although EPA is
  open to alternatives that commenters may propose. See Section III for a more detailed discussion of this
  issue.
Source: Engine Manufacturers Association.


[[Page 4142]]


     Table 3.--Engine Manufacturers Association Estimates of Percent PM Emissions From Non-Emergency Engines
----------------------------------------------------------------------------------------------------------------
              Engine ratings                    < 1980       1980-1995     1996-2001     2002-2005      Totals
----------------------------------------------------------------------------------------------------------------
>=50 and <100 BHP.........................           1.3           2.4           0.7           0.3           4.7
>=100 and <175 BHP........................           5.0           6.5           1.3           0.4          13.2
>=175 and <300 BHP........................           4.1           7.8           1.8           0.6          14.3
>=300 and <600 BHP........................          20.1          11.3           2.5           0.9          34.8
>=600 and <750 BHP........................           3.7           4.0           1.1           0.4           9.2
>=750.....................................           4.4          13.9           5.0           0.7          24
                                           ---------------------------------------------------------------------
    Totals................................          38.6          45.9          12.4           3.3         100.2
----------------------------------------------------------------------------------------------------------------
          Percent PM Emissions from non-emergency engines 300 BHP built prior to 1996: 57.4.
----------------------------------------------------------------------------------------------------------------
Notes:
 The percent estimates are based on an Engine Manufacturers Association assumption that non-emergency
  engines operate about 2,000 hours/year. EPA in its rulemaking analyses assumes about 1,000 hours/year of
  operation for non-emergency engines. The 2,000 hours/year assumption is used here because we are using the
  most readily available information that the Engine Manufacturers Association has provided to EPA. However, EPA
  would not expect the percent estimates in this table to differ significantly under the 1,000 hours/year EPA
  assumption.
 Emissions estimates based on EPA AP-42 emission factors and recent mobile source emission factors:
  http://www.epa.gov/ttn/chief/ap42/ch03/index.html.

 Total percent does not equal 100 due to rounding.
Source: Engine Manufacturers Association.


  Table 4.--U.S. Environmental Protection Agency Estimates of Percent HAP Emissions From Non-Emergency Engines
----------------------------------------------------------------------------------------------------------------
               Engine ratings                    < 1980       1980-1995     1996-2001     2002-2005      Totals
----------------------------------------------------------------------------------------------------------------
>=50 and <100 BHP..........................           0.5           1.4           0.5           0.2          2.6
>=100 and <175 BHP.........................           2.5           4.9           1.1           0.5          9.1
>=175 and <300 BHP.........................           2.3           6.6           1.7           1.0         11.7
>=300 and <600 BHP.........................          17.4          14.6           2.4           2.3         36.7
>=600 and <750 BHP.........................           4.4           7.1           1.1           1.0         13.5
>=750......................................           2.7          12.7           9.3           1.7         26.4
                                            --------------------------------------------------------------------
    Totals.................................          29.9          47.4          16.1           6.6        100.0
----------------------------------------------------------------------------------------------------------------
         Percent HAP Emissions from non-emergency engines 300 BHP built prior to 1996: 58.9.
----------------------------------------------------------------------------------------------------------------
Notes:
 Percent estimates based on assumption that non-emergency engines run about 1,000 hours/year. EPA in its
  rulemaking analyses assumes about 1,000 hours/year for non-emergency engines.
 HAP emissions estimates include: Formaldehyde, acetaldehyde, polycyclic aromatic hydrocarbons,
  naphthalene, and acrolein.
 Emissions estimates based on EPA AP-42 emission factors and recent mobile source emission factors:
  http://www.epa.gov/ttn/chief/ap42/ch03/index.html.

Source: U.S. Environmental Protection Agency.

III. Specific Issues on Which EPA Is Seeking Comment

    Although we have some limited information about larger, older 
stationary diesel engines, we have a need for more detailed and current 
data related to existing engines. We are issuing this ANPR to request 
information that will help inform our efforts on how best to control 
emissions from these engines. There are several issues that we need to 
understand more fully in order to implement a program for existing 
stationary diesel engines. In this section, we break down the specific 
areas of interest for which we are requesting comment.

A. What particular subgroups of existing stationary diesel engines 
should EPA focus on and how can EPA best find information on those 
engines?

    Currently, EPA is considering focusing on non-emergency diesel 
engines that were built before 1996 and that are rated greater than 300 
BHP, although EPA is open to alternatives that commenters may propose 
that are well supported with appropriate data. We are focusing on non-
emergency engines, because, while they represent only 20% of the total 
number of stationary engines, they are responsible for a significant 
amount of HAP emissions from stationary engines. EPA is considering 
focusing on pre-1996 engines because, generally speaking, emissions 
controls were not implemented in a significant way on nonroad diesel 
engines until the 1996 engine model year. Thus, the pre-1996 engines 
represent stationary engines that EPA believes are largely 
uncontrolled. In addition, diesel retrofit controls are typically more 
cost effective and technically feasible the larger the engine.\ 30\ 
When these three criteria are combined, it comprises a set of larger, 
older non-emergency engines that represent the majority of PM and 
toxics emissions from non-emergency engines as a whole (see Tables 3 
and 4).
---------------------------------------------------------------------------

    \30\ For more information, see ``The Cost-Effectiveness of 
Heavy-Duty Diesel Retrofits and Other Mobile Source Emission 
Reduction Projects and Programs,'' U.S. Environmental Protection 
Agency, EPA420-B-07-006, http://www.epa.gov/cleandiesel/publications.htm, 

May 2007.
---------------------------------------------------------------------------

    While we believe this is an appropriate set of engines to focus on, 
we are requesting comment on whether there are other appropriate 
categories of engines that should also be considered. For example, 
should EPA consider requiring emission reductions for non-

[[Page 4143]]

emergency stationary diesel engines built in the late 1990s 
(notwithstanding our estimates that total emissions from these engines 
are lower). The list below further explores diesel control technologies 
and associated emission reduction issues.
    Particular areas for categorization of engines on which we could 
focus include:
     The model year of the engine, including engines built 
since 1996 and remaining useful engine life for older engines;
     The type and size of engine, including engines rated less 
than 300 BHP in size;
     The number of hours of operation and/or time profile 
annually or over a shorter term;
     The applicable technologies, and corresponding emissions 
reductions available, for given ages and sizes of engines;
     The duty cycle;
     The sector or use;
     The ability of engine owners and operators to access the 
lower sulfur fuel necessary to ensure the proper performance of 
pollution control devices;
     Ease of installation and cost effectiveness of emissions 
reductions associated with controls on existing stationary diesel 
engines, including newer, later model year engines; and
     Any other distinguishing characteristics commenters may 
think important.

B. Where can EPA find better information about the location and numbers 
of existing stationary engines, who owns and operates them and what 
impact they are having (including hours of operation)?

    Above, EPA lays out the general information it has available on the 
numbers of stationary diesel engines believed operating today. EPA 
specifically estimates that there are approximately 36,000 non-
emergency, pre-1996 stationary diesel engines larger than 300 BHP. EPA 
seeks comment on the accuracy of these numbers, as well as of the other 
estimates in Tables 3 and 4. EPA is requesting any information that 
informs its understanding of the number and distribution of these 
stationary diesel engines and the group(s) that would be most affected 
by any requirements to reduce emissions.
    We also lack detailed information on the location of these sources, 
including their owners and operators. If EPA proposes standards based 
on engine size and age criteria, then we would need detailed 
information on the location or the owners and operators of these 
sources.
    We are aware of the following information sources from which we 
need information that we currently lack:
     State-managed permit databases;
     State-gathered information through surveys and other 
means;
     Engine manufacturer and owner/operator and fuel industry 
information such as fuel distribution/delivery records, and fuel 
storage tank sales, repairs, and permits;
     Industry sectors that are major owners and operators of 
diesel engines, including their trade associations such as the 
Interstate Natural Gas Association of America and the American 
Petroleum Institute; and
     Diesel control technology manufacturers.
    We would like to know if states have an accurate count of the 
number of engines operating in the state, including their purpose and 
hours of operation. If so, EPA is also interested in the source of the 
information (e.g., a state permit database). We are also interested in 
any small business impacts and other relevant information about the 
owners and operators and number of hours that these engines operate.

C. What are appropriate and available technically-feasible, cost-
effective methods of controlling emissions from existing stationary 
diesel engines?

    EPA seeks information on control technologies and other methods for 
reducing diesel HAP emissions from existing stationary diesel engines, 
particularly for non-emergency, pre-1996 engines that are rated greater 
than 300 BHP. These methods include, but are not limited to, one or 
more of the following:
     Retrofitting with diesel particulate filters, including 
both actively and passively regenerated filters;
     Retrofitting with partial flow filters;
     Retrofitting with oxidation catalysts;
     Retrofitting with closed crankcase ventilation systems;
     Engine recalibration or fuel system upgrade;
     Replacement with new, state-of-the-art engines;
     Use of low sulfur diesel (500 parts per million (ppm)) or 
ULSD (15 ppm) fuel;
     Use of fuel substitution systems using natural gas;
     Use of biodiesel; and
     Management practices.
    EPA understands that there may be limitations, both economic and 
technical, to certain control methods and solicits engine emissions 
testing data, cost data and other information to inform our approach to 
these issues. For example, EPA would like clarification on the 
following:
     The extent to which low sulfur and ULSD fuel may be 
problematic in certain older engines due to fuel system seal leakage 
and how this problem has been addressed through fuel additives and/or 
modifications to mobile source engines;
     Potential for the malfunction of diesel retrofit devices 
on older engines (e.g., diesel particulate filters), the engine 
conditions that lead to this problem, and appropriate precautions to 
avoid malfunction;
     Technical feasibility of controls for short use periods 
(e.g., need for controls to warm up in order to be effective, the need 
for these engines to start immediately without mechanical 
complications);
     Cost-effectiveness of controls on existing engines (i.e., 
emissions reductions relative to cost and hours operated);
     Cost, availability and emissions related to fuel 
substitution systems using natural gas;
     The equipment and operating costs (and any challenges, 
including safety issues) associated with known control technologies;
     Engine size limitations beyond which a control technology 
may become infeasible and for what reason; and
     Any other technical and economic feasibility issues that 
would affect the control of emissions reductions from older, larger and 
smaller diesel engines.

D. To what degree do state and local governments regulate emissions 
from stationary diesel engines?

    EPA requests comment on the extent to which state and local 
governments have issued regulations to reduce emissions from stationary 
diesel engines of all sizes, particularly the larger, older engines. 
EPA is aware, for example, that the States of California \31\ and 
Wisconsin \32\ have issued rules that mandate reductions of particulate 
emissions from existing stationary diesel engines. EPA is interested in 
information about other state and local governments that have issued

[[Page 4144]]

regulations controlling emissions from existing stationary diesel 
engines.
---------------------------------------------------------------------------

    \31\ For more information on the California rule, see: 
``Airborne toxic control measure for stationary compression ignition 
engines,'' section 93115, title 17, California Code of Regulations, 
http://www.arb.ca.gov/diesel/ag/documents/finalatcm.pdf.

    \32\ For more information on the Wisconsin rule, see: ``Fuel, 
control and compliance requirements for compression ignition 
internal combustion engines combusting fuel oil,'' section NR 
445.09, http://www.legis.state.wi.us/rsb/code/nr/nr445.pdf.

---------------------------------------------------------------------------

E. What are appropriate methods of ensuring compliance with such 
requirements, including recordkeeping and testing issues?

    Given the large population of stationary diesel engines and our 
lack of information on the location and owners and operators of these 
engines, EPA requests comment on effective methods to ensure compliance 
with any emission reduction requirements. EPA also requests comment on 
the extent to which the owners and operators of these engines are small 
businesses and on what the appropriate regulatory compliance 
requirements should be for those entities. EPA is especially interested 
in ways to minimize the monitoring burden to individual owners and 
operators, while maintaining an appropriate level of environmental 
protection.

IV. How EPA Intends To Proceed Following Publication of This Notice

    Following the closing of the comment period for this notice, EPA 
will summarize and analyze the comments received. The summary and 
analysis will be used to help develop and inform the notice of proposed 
rulemaking that will follow this notice.

 V. Statutory and Executive Order Reviews

    Under Executive Order (EO) 12866 (58 FR 51735, October 4, 1993), 
this action is a ``significant regulatory action.'' Accordingly, EPA 
submitted this action to the Office of Management and Budget (OMB) for 
review under EO 12866 and any changes made in response to OMB 
recommendations have been documented in the docket for this action. 
Generally, because this action is ``advanced'' in nature and does not, 
therefore, propose any requirements on any entities, the various 
administrative requirements EPA must address in the rulemaking process 
are not applicable. When EPA issues a notice of proposed rulemaking 
that contains proposed emissions standards for stationary diesel 
engines, EPA will address those requirements.

Lists of Subjects in 40 CFR Part 63

    Environmental protection, Air toxics.

    Dated: January 16, 2008.
Stephen L. Johnson,
Administrator.
[FR Doc. E8-1118 Filed 1-23-08; 8:45 am]

BILLING CODE 6560-50-P
