Significant New Alternatives Policy Program

Fire Extinguishing and Explosion Prevention Sector

Risk Screen on Substitutes for Halon 1301

Total Flooding Systems in Normally Occupied and Unoccupied Spaces

Substitute: ATK OS-10

This risk screen does not contain Clean Air Act (CAA) Confidential
Business Information (CBI) and, therefore, may be disclosed to the
public.



Introduction

Ozone-depleting substances (ODS) are being phased out of production in
response to a series of diplomatic and legislative efforts that have
taken place over the past decade, including the Montreal Protocol and
the Clean Air Act Amendments of 1990 (CAAA).  The U.S. Environmental
Protection Agency (EPA), as authorized by Section 612 of the CAAA, is
developing a program to evaluate the human health and environmental
risks posed by alternatives to ODS.  The main purpose of EPA's program,
called the Significant New Alternatives Policy (SNAP) program, is to
identify acceptable and unacceptable substitutes for ODS in specific end
uses.  

EPA’s decision on the acceptability of a substitute is based largely
on the findings of a screening assessment of potential human health and
environmental risks posed by the substitute in specific applications. 
EPA has already screened a large number of substitutes in many end uses
within all of the major ODS-using sectors, including refrigeration and
air conditioning, solvent cleaning, foam blowing, aerosols, fire
suppression, adhesives, coatings and inks, and sterilization.  The
results of these risk screens are presented in a series of Background
Documents that are available in EPA's docket.

The purpose of this risk screen is to supplement EPA’s Background
Document on the fire suppression and explosion protection sector
(hereinafter referred to as the Background Document, EPA 1994). This
risk screen discusses potential human health and environmental risks
posed by the ATK OS-10 system when used as a replacement for Halon 1301
for use as a total flooding system in normally occupied and unoccupied
spaces.

The OS-10 system produces post-activation products mainly consisting of
gases and some particulates.  The pre-activation products are summarized
below in   REF _Ref214866528 \h  \* MERGEFORMAT  Table 1-1  and the
post-activation products in   REF _Ref214866472 \h  \* MERGEFORMAT 
Table 1-2 .  

Table   STYLEREF 1 \s  1 -  SEQ Table \* ARABIC \s 1  1 :  Composition
of ATK, Prior to Activation

Constituent	Chemical Formula	CAS #	% of Total by Weight

Gas Generanta



Ignition Material



a The submitter notes that [] will be added to the generant once full
production begins.  It will be []% of the total by weight.  []

Table   STYLEREF 1 \s  1 -  SEQ Table \* ARABIC \s 1  2 :  Composition
of ATK, Post-Activation

Constituent	Chemical Formula	CAS #	% of Total by Weight

Gaseous

Water Vapor	H2O	7732-18-5

	Nitrogen	N2	7727-37-9



	Particulate



* The percentages in this table are based on the amount of matter that
is discharged from the system and do not take into account the material
remaining in the generator as residue. 

OS-10 systems consist of gas generators that are intended to be used
either singly or as several grouped together in a casing that also
contain the controls for the firing sequence, a heat management portion
and a particulate filter.  Each generator contains [] pounds of the
pre-activation mixture of chemicals (see   REF _Ref214866528 \h  \*
MERGEFORMAT  Table 1-1 ).  The generator includes a pyrotechnic igniter
and a diffuser through which the hot gas is released. A single gas
generator is capable of extinguishing a heptane fire in a volume of 220
cubic feet with a safety factor of 1.3 on the agent quantity (ATK
2008a).

OS-10 systems are intended to be used in a variety of commercial,
industrial, and marine applications including protection of data
centers, shipboard machinery spaces, and telecommunication facilities. 
Applications also include the protection of selected spaces in
aircrafts, ships, and vehicles. (ATK 2008a)

To ensure that use of OS-10 in the applications listed above will not
pose unacceptable risks to workers or the general public, worst case
occupational exposure (during manufacturing, installation and
maintenance, and post-activation clean up) and general population
analyses were performed.  Consumer exposure modeling was not performed
because no consumer applications are proposed for this system.

The remainder of this risk screen is organized as follows:

Section 2 of this report summarizes the results of the risk screen for
OS-10;

Section 3 presents atmospheric modeling; 

Section 4 discusses occupational exposure during manufacturing,
installation, and maintenance; 

Section 5 discusses exposure at the end-use;

Section 6 assesses risks associated with general population exposure;
and 

Section 7 assesses the emissions of volatile organic compounds.

Summary of Results

ATK OS-10 is recommended for SNAP approval as a total flooding device in
normally occupied and unoccupied spaces.  Section VIII of the
Occupational Safety & Health Administration (OSHA) Technical Manual
(OSHA 1999) should be consulted for information on selecting the
appropriate types of personal protective equipment (PPE) to be worn by
personnel involved in the manufacture, installation, maintenance or
clean-up of OS-10.  It is expected that level C of the levels of
protection presented in the Manual will provide appropriate protection
(see Appendix A for a description of level C protection).  The risk
screen indicates that the use of the proposed substitute will be less
harmful to the atmosphere than the continued use of Halon 1301. 
Additionally, the risk to the general population is expected to be below
levels of concern for non-cancer risks.  EPA recommends that use of this
system should be in accordance with the safe exposure guidelines for
inert gas systems in the latest edition of NFPA 2001, specifically the
requirements for residual oxygen levels, and should be in accordance
with the relevant operational requirements in NFPA Standard 2010 for
Aerosol Extinguishing Systems. 

Atmospheric Modeling 

This section presents an assessment of the potential risks to
atmospheric integrity posed by the use of OS-10 as a total flooding
system in normally occupied/unoccupied areas.  The global warming
potentials (GWP) of the gaseous post-activation products released upon
activation of the fire suppressant are listed below in   REF
_Ref214866980 \h  \* MERGEFORMAT  Table 3-1 .  All products have an
ozone-depletion potential (ODP) of zero.

Table   STYLEREF 1 \s  3 -  SEQ Table \* ARABIC \s 1  1 : GWPs of the
Gaseous Post-Activation Products of OS-10

Constituent	GWP

H2O	0a

N2	0



NA Not available

Source: IPCC, 2001, unless otherwise noted.

aAlthough water vapor is a greenhouse gas, human activities are not
thought to directly affect the average global concentration of water
vapor (EPA, 2002).  There is no IPCC published GWP for water vapor.

bCalm and Hourahan, 2007

The GWPs of post-activation products in OS-10 are well below the GWPs of
previously SNAP-approved fire-suppression agents (e.g. HFCs and other
high-GWP fluids).  Accordingly, use of OS-10 is not expected to pose any
significant adverse atmospheric impacts.

Occupational Exposure

The potential for personnel exposure during manufacture, installation
maintenance, and cleanup are examined in this section. The discharge
scenarios discussed are assumed to occur accidentally and not as the
result of a fire.

Exposure During Manufacture

During manufacturing operations, workers may be exposed to [] while
conducting various activities during the production process (ATK 2008a).
 Safeguards (i.e., PPE requirements) for each have activity been
developed by ATK based on air samples collected during previous
production runs of similar constituents.  During production of OS-10,
exposure levels of the various constituents are expected to be similar
to those observed in the previous production runs (ATK 2008b). 
Therefore, the PPE used during the previous runs should be appropriate
for use during OS-10 manufacture.  ATK should continue to follow good
workplace hygiene and should monitor concentrations of constituents
present during manufacture once OS-10 production begins to ensure that
the PPE are still sufficient. 

Exposure During Installation and Maintenance 

Installation and maintenance personnel should receive training so as to
minimize the risk for accidentally discharging the system while
performing installation or maintenance activities. If accidental
dispersion of the system does occur while workers are in the protected
volume, no significant adverse health effects should result if workers
vacate the space during the five-minute egress time established by NFPA
2010 (NFPA 2006).  Refer to Section   REF _Ref216581161 \r \h  \*
MERGEFORMAT  5  for a detailed discussion on exposure to the substitute
during this five-minute period.

Users of the system should consider the installation of oxygen
masks/tanks, safety showers and other treatment materials outside the
room where people can reach them within five minutes in the event of
accidental release.  

Exposure During Cleanup

Testing data provided by the submitter do not indicate that there will
be a significant amount of particulate left in the room post-release. 
 Prior to cleanup, the air exchange rate in the room should be
increased in order to aerate the space and reduce humidity.  As clean-up
operations may result in the re-circulation of dust particles, it is
recommended that all workers entering the protected volume to clean-up
after activation wear appropriate PPE.   It is expected that level C of
the levels of protection presented in the OSHA Technical Manual (OSHA
1999) will provide appropriate protection. 

The contents removed from the protected volume should be disposed of
according to federal, state and local regulations.  When recommended
safety precautions are followed, no significant adverse health effects
should result. 

Exposure At End-Use

When the ATK system is activated, gaseous compounds and particulate
matter are emitted.  The following sections examine exposures to the
gaseous effluent, the components of the particulate matter and nuisance
dust.  

Exposure to Gaseous Effluent

  REF _Ref216582038 \h  \* MERGEFORMAT  Table 5-1  presents the
concentrations of each gaseous effluent present after dispersion of the
system, as determined in testing by ATK.  The table also includes
relevant toxicity limits for each constituent.

  

Table   STYLEREF 1 \s  5 -  SEQ Table \* ARABIC \s 1  1 . Concentrations
of Gaseous Effluent and Relevant Toxicity Limits

	ATK Test Levels	National Research Council Emergency Exposure Guideline
Levels (EEGLs)	Immediately Dangerous to Life and Health (IDLH)a	Acute
Exposure Guideline Levels (AEGLs)

Gas	10 Minute TWA (ppm)	10 min (ppm)	30 min (ppm)	AEGL-2b	AEGL-3c





10 min	30 min	10 min	30 min



NA = Not Available

a IDLH values are defined as the maximum exposure concentration of a
given chemical in the workplace from which one could escape within 30
minutes without any escape-impairing symptoms or any irreversible health
effects.

b AEGL-2: The airborne concentration of a substance above which it is
predicted that the general population, including susceptible individuals
could experience irreversible or other serious, long-lasting adverse
health effects or an impaired ability to escape.

c AEGL-3: The airborne concentration of a substance above which it is
predicted that the general population, including susceptible
individuals, could experience life-threatening health effects or death.

d No Rec: No recommendation due to insufficient data.

e AEGL values for [] are recommended due to the greater toxicity of [].

IDLH levels are developed to be protective of human health in the event
of a 30-minute exposure.  To supplement these values, AEGLs and EEGLs
are also used, both of which provide more acute exposure scenarios
(i.e., 10-minute exposure levels).  These levels should be closer in
magnitude to a 5-minute exposure limit, the expected maximum exposure
time in case of accidental release. The main results are summarized
below:

Concentrations of [], [] and [] resulting from an accidental release are
not anticipated to be problematic, based on comparison to AEGL and IDLH
values.

The concentration of [] is well below the AEGL-3 values (even at 30
minutes) and should not result in irreversible health effects in exposed
individuals, although eye and mucus membrane irritation may result
following exposure.   

It is not expected that exposure to the concentration of [] present
after activation of OS-10 (i.e., [] ppm) for only 5 minutes will cause
adverse effects.  See Section   REF _Ref217709216 \r \h  5.1.1  for a
more detailed discussion regarding the exposure level of [].

Therefore, no adverse health effects are expected due to exposure to the
gaseous effluents during the five-minute egress time established by NFPA
2001 (NFPA 2008).

[]

[]  

Table   STYLEREF 1 \s  5 -  SEQ Table \* ARABIC \s 1  2 .  Dose-Response
Table of Levels of [] and [] Resulting from Treatment []

Newborns with gestational age ≥ 34 weeks	12 hours





Moreover, EPA has concluded “that for [], if the concentration is not
high enough to be lethal due to [] formation, the animal recovers
completely.”  Therefore, EPA does not recommend acute exposure
guidelines level (AEGL) values for [] and instead recommends that AEGL
values for [] be used for emergency planning for [], as conversion of []
to [] occurs and [] is more toxic than [] (EPA 2006). 

Exposure to Particulate Matter

  REF _Ref216588398 \h  \* MERGEFORMAT  Table 5-3  presents
concentrations of particulate matter measured during testing conducted
by ATK and relevant toxicity limits for the substances.

Table   STYLEREF 1 \s  5 -  SEQ Table \* ARABIC \s 1  3 . Concentrations
of Particulate Matter and Relevant Toxicity Limits

Particulate Compounds 	Concentration at 5 minutes (mg/m3)	OSHA mg/m3

(TWA: 8hrs)	OSHA mg/m3

(TWA: 15min)a

Acid Soluble Portion



Water Soluble Portion



Total Particulate 



a Assuming that all exposure takes place in the time span of 15 minutes,
the 8-hour TWA can be converted to a 15-minute TWA using the following
equation: 15-minute TWA (mg/m3) =  (8-hr TWA  x 480 minutes)/15 minutes

b[]

c NIOSH, 2007

d []

e []

At the levels reported by the submitter, the particulate matter should
not be detrimental to human health.  While exposure to the reported
level of [] does not present toxicity concerns, given the irritating
nature of the compound, further information on exposure to this compound
is presented in Section   REF _Ref216588620 \r \h  \* MERGEFORMAT  5.2.1
.  

Users of the system should consider the installation of oxygen
masks/tanks, safety showers and other treatment materials outside the
room where people can reach them within five minutes in the event of
accidental release.  

[]

[] 

Although contact with [] may be uncomfortable, there are no toxicity
concerns with the post-activation levels.  The submitter reports the
concentration of [] will be [] mg/m3 at five minutes.  This level is
well below the eight hour OSHA TWA of [] mg/m3.

Exposure to Nuisance Dust

OS-10 contains a total particulate concentration at five minutes of []
mg/m3 for all particulates.  The nuisance dust OSHA PEL TWA is 15.0
mg/m3 for eight hours and calculated as 480mg/m3 for fifteen minutes. 
The nuisance dust level of ATK should not present a toxicity threat
since room occupants will only be exposed to this dust level for five
minutes; however, irritation during respiration or impaired visibility
may occur.

General Population Exposure

This section screens potential risks to the general population from
exposure to ambient air releases of OS-10 constituents.  Factory
releases (occurring during manufacture) and on-site releases (those
occurring at the end-use) are examined in this section. By following
existing regulations, factory or on-site releases are not likely to pose
a significant threat to ambient air, surface water, or solid waste. 
Consequently, use of OS-10 is not expected to pose significant risk to
the general population.   

Ambient Air

The submitter indicated no anticipated releases to the atmosphere at
manufacture.  On-site releases that result in the discharge of gases are
not expected to pose a threat to the general public.  ATK indicates that
state of the art detection/control systems will eliminate unwanted
discharges.  Controlled discharge of nitrogen and water vapor to the
atmosphere will occur.  This will not pose a threat to the general
public given the concentrations of these constituents naturally present
in the atmosphere.  Therefore, air emissions associated with the
manufacture and use of OS-10 are not of concern to the health of the
general population.   

Surface Water

If all the solid waste settles onto the floor of the space and is
removed from the site according to federal, state, and local
requirements, the OS-10 components are not likely to settle into nearby
streams or ponds. 

Solid Waste 

If all spilled and settled material in the manufacturing facility and
all on-site releases are cleaned up and disposed of according to
federal, state, and local requirements, no release to the environment is
expected.  

Volatile Organic Compound Analysis

The OS-10 constituents are not considered VOCs for purposes of local air
quality.    

References

ATK. 2008a. Significant New Alternatives Policy Program Submission to
the United States Environmental Protection Agency, May 2008. 

ATK.  2008b.  	Letter to Bella Maranion, U.S. EPA.  26 August 2008

Calm, James and Glenn Hourahan. 2007. “Refrigerant Data Update.”
Heating/Piping/Air Conditioning Engineering. 79(1): 50-64. January 2007.
Available at <   HYPERLINK
"http://members.cox.net/jamesmcalmpubs2/Calm_Hourahan-Refrigerant_Data_U
pdate-HPAC_Engineering-2007.pdf" 
http://members.cox.net/jamesmcalmpubs2/Calm_Hourahan-Refrigerant_Data_Up
date-HPAC_Engineering-2007.pdf >.

[]

EPA. 2006. Acute Exposure Guidelines Levels (AEGLs) for []. October
2006. Available online at [].

EPA, 2002.  Inventory of U.S. Greenhouse Gas Emissions and Sinks:
1990-2000.

EPA.  1994. Risk Screen on the Use of Substitutes for Class I
Ozone-Depleting Substances: Fire Suppression and Explosion Protection
(Halon Substitutes).  Stratospheric Protection Division.  March 1994. 

[]

IPCC, 2001.  Third Assessment Report: Climate Change 2001: The
Scientific Basis.  International Panel on Climate Change.  Available
online at http://www.grida.no/climate/ipcc_tar/.

NFPA. 2008. NFPA 2001: Standard on Clean Agent Fire Extinguishing
Systems.  National Fire Protection Agency.  

NFPA. 2006.  NFPA 2010: Standard for Fixed Aerosol Fire-Extinguishing
Systems.  National Fire Protection Agency.    

NIOSH.  2007.  NIOSH Pocket Guide to Chemical Hazards.  Department of
Health and Human Services, Centers for Disease Control and Prevention,
National Institute for Occupational Safety and Health.  Publication No.
2005-149.  September 2007.

OSHA.  1999.  OSHA Technical Manual. Department of Labor.  Occupational
Safety and Health Administration. January 20, 1999.  Available online at
  HYPERLINK "http://www.osha.gov/dts/osta/otm/otm_toc.html" 
http://www.osha.gov/dts/osta/otm/otm_toc.html .

[]

[]

[]

Appendix A – Description of PPE Protection Level C

OSHA’s Technical Manual (OSHA 1999) defines “level C” protection
as follows:

“Support Function Protective Garment (meets NFPA 1993)

Full-facepiece, air-purifying, canister-equipped respirator

Chemical resistant gloves and safety boots

Two-way communications system, hard hat 

OPTIONAL: Faceshield, escape SCBA 

Protection Provided: The same level of skin protection as Level B, but a
lower level of respiratory protection. Liquid splash protection but no
protection to chemical vapors or gases. 

Used When: Contact with site chemical(s) will not affect the skin. Air
contaminants have been identified and concentrations measured. A
canister is available which can remove the contaminant. The site and its
hazards have been completely characterized. 

Limitations: Protective clothing items must resist penetration by the
chemical or mixtures present. Chemical airborne concentration must be
less than IDLH levels. The atmosphere must contain at least 19.5%
oxygen.

Not Acceptable for Chemical Emergency Response”

Appendix A References

OSHA.  1999.  OSHA Technical Manual. Department of Labor.  Occupational
Safety and Health Administration. January 20, 1999.  Available online at
  HYPERLINK "http://www.osha.gov/dts/osta/otm/otm_toc.html" 
http://www.osha.gov/dts/osta/otm/otm_toc.html .

 AEGLs are intended to describe the risk to humans resulting from rare
exposure to airborne chemicals.

 Assuming that all exposure takes place in the time span of 15 minutes,
the 8-hour TWA can be converted to a 15-minute TWA using the following
equation: 15-minute TWA (mg/m3)  = (15mg/m3 x 480 minutes)/15 minutes=
480 mg/m3

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December 23, 2008

