Risk Screen on Substitutes for Halon 1301

Fire Suppression and Explosion Protection Applications

Proposed Substitute: Aero-K® 

Total Flooding Applications in Unoccupied Spaces

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 report is to supplement EPA’s Background Document
on the fire suppression and explosion protection sector (hereinafter
referred to as the Background Document).1  This risk screen discusses
potential human health and environmental risks posed by Aero-K® Fire
Suppressant, as a replacement for Halon 1301, used as a total flooding
agent in unoccupied spaces such as electrical cabinets, engine
compartments, turbine enclosures, flammable liquid storage, and remote
cellular base stations.  

							

Aero-K® is a pyrotechnic particulate aerosol and explosion suppressant
supplied to end users as a solid housed in a double walled hermetically
sealed steel container.  When the unit is triggered (300C), the
product is pyrotechnically activated to produce gases and aerosol
particles from a mixture of chemicals, one of which is known to be a
strong oxidizer and potentially toxic (Mallinckrodt Chemicals and JT
Baker Inc., 1999).  This pyrotechnic composition passes through a bed of
catalytically active substrate that cools, oxidizes, and filters the
particulates (minimizing the number of particles <1 µm) of the mixture.
 Occupational exposure, exposure at end use, and general population
analyses were performed to ensure that use of the proposed blend in the
applications listed above did not pose unacceptable risks to workers or
the general public.  Consumer exposure modeling was not performed
because no consumer applications are proposed for the blend.  Table 1
provides the composition of Aero-K®.

Table 1.  Composition of Aero-K® Fire Suppression Aerosol Generator,
Prior to Activation

Constituent	Chemical Formula	CAS No.	Percent of Total (by weight)















	

Section 2 of this report summarizes the results of the risk screen for
Aero-K® in flooding applications.  Section 3 presents atmospheric
modeling and potential environmental risks; Section 4 discusses
occupational exposure; Section 5 discusses exposure at end use; Section
6 assesses risks associated with general population exposure; and
Section 7 assesses the emissions of volatile organic compounds.

Summary of Results

Aero-K® is recommended for SNAP approval as an extinguisher or as a
total flooding device in unoccupied spaces.  However, workers should
wear safety goggles and appropriate protective clothing (e.g., chemical
suits, goggles, and particulate respirators) during the manufacture,
clean up, and disposal of this product.  The risk screen indicates that
the use of the proposed substitute in unoccupied spaces 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.  For applications of this and
all other fire suppression equipment, EPA recommends that the applicable
National Fire Protection Agency (NFPA) standards be followed.

											

Atmospheric Modeling

This section presents an assessment of the potential risks to
atmospheric integrity posed by the use of Aero-K® as a fire
extinguisher in unoccupied areas.  According to the submitter, the
active ingredients for this technology are solids both before and after
use; thus, the ozone-depleting potential (ODP) and the atmospheric
lifetime (ALT) are both zero (Aero-K® SNAP Submission 2003).  The
gaseous post-activation products are released upon activation of the
fire suppressant (Aero-K® SNAP Submission 2001).  The concentrations
released are not expected to result in significant adverse atmospheric
impacts, thus the use of Aero-K® is not expected to pose any
significant adverse atmospheric impacts.  Additionally, the GWPs of
post-activation compounds in Aero-K® are well below the GWPs of
previously SNAP-approved fire-suppression agents (e.g. HFCs and other
high-GWP fluids).

 												

Occupational Exposure at Manufacture

Worker exposure during the manufacturing process is precluded by the use
of appropriate protection equipment.  The constituents of Aero-K® do
not have published occupational exposure limits; however these
constituents are known mucus membrane, eye, skin, respiratory tract, and
gastrointestinal irritants. Limited toxicity data is available for the
constituents. As described by the submitter, there is limited exposure
to the product during manufacturing. Production facilities are ISO 9002
certified and qualified for (Military) MIL procedures. Worker exposure
may occur during the production of charges, which involves blending and
pressing the components and assembly of the generators containing the
charge. All employees involved in any step of the manufacturing process
should wear chemical suits, gloves, particulate respirators (NIOSH type
N95 or better filters) and goggles. The manufacturing space should be
well ventilated with a local exhaust system to reduce airborne exposure
of the Aero-K® constituents.  In the case of an accidental spill,
workers should wear their protective equipment while wet vacuuming the
particulate matter.  An eye wash fountain and quick drench facilities
must be close by the production area. 

EPA finds that the use of these exposure controls and adherence with the
appropriate occupational safety guidelines are sufficient to ensure that
the manufacture of Aero-K® does not pose a risk to human health.

  SEQ CHAPTER \h \r 5 Exposure at End Use

If the Aero-K® fire suppression aerosol generator is automatically
activated in unoccupied spaces, a warning system deploys both an alarm
and a 60-second delay with a lockout mechanism if personnel are in the
area. In the event of discharge, all personnel should be required to
wear goggles, gloves, and self-contained breathing apparatus (SCBA).

It is noted that upon activation, several post-activation products are
expected to form. Table 2 presents these products and concentrations
measured by a contract laboratory for the manufacturer (Aero-K® SNAP
Submission 2003).

Table 2.  Post-Activation Products from a Discharge of 

Aero-K® Fire Suppression Aerosol Generator

  SEQ CHAPTER \h \r 1 Compound	Chemical Formula	CAS No.	Percent of Total

(by weight)

Gas













































	Particulate

























	Note:  The original percentages, reported in the Aero-K® submission
were incorrect.  Therefore, the submitters have provided the corrected
percentages above.  

Other Toxicity Endpoints

An acute eye irritation (Draize) and acute inhalation test are not
required for Aero-K® if it is used in unoccupied spaces.  The results
from such tests have not been reported; this data gap must be addressed
prior to SNAP review for occupied spaces. 

Post-Activation Disposal

Workers should not enter the space following discharge until all
particles have settled and the gases released by the system have
dissipated.  The submitter should provide guidance upon installation
regarding the appropriate time frame after which workers may enter the
activation site for disposal to allow the maximum settling of all the
particulates. Clean-up operations are likely to result in the
re-circulation of potentially toxic dust particles.  Therefore, workers
entering the protected volume to clean-up after activation are required
to wear chemical suits, gloves, goggles, and a particulate removing
respirator with a fine dust rating capability.  The contents removed
from the protective volume should be disposed of according to approved
safety procedures.  Equipment should be thoroughly decontaminated after
use.  When recommended safety precautions are followed, no significant
adverse health effects should result. 

General Population Exposure

This section screens potential risks to the general population from
exposure to ambient air releases of Aero-K®, blend constituents, or
post-activation products.  Factory releases (occurring during
manufacture) and on-site releases (those occurring at the end-use) are
examined in this section.  By following existing regulations and
installing the proper control systems, EPA believes that factory or
on-site releases are not likely to pose a significant threat to ambient
air or surface water. Additionally, the releases do not pose threats
associated with solids wastes. Consequently, use of Aero-K® is not
expected to pose a significant risk to the general population.

Ambient Air

All manufacturing occurs in the facility with a closed ventilation
system; therefore, minimal release to the ambient air is expected.  All
facility emissions are controlled and regulated. Therefore, air
emissions associated with the use of the Aero-K® fire suppression
system are not of concern to the health of the general population. 

Surface Water   TC \l3 " 

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

Solid Waste

All spilled or settled material in the manufacturing facility is
considered hazardous and should be treated accordingly.  If all federal,
state, and local regulations pertaining to waste disposal are followed,
no release to the environment is expected.

Volatile Organic Compound Analysis 

In Chapter 7 of the Background Document (US EPA 1994), EPA estimated the
impact of potential increases in volatile organic compound (VOC)
emissions from the use of substitutes for ozone-depleting substances. 
The concentration of VOCs resulting from the activation of Aero-K are so
small that the use of Aero-K is not expected to lead to a significant
increase of VOCs in the atmosphere.  

References

Aero-K® SNAP Submission.  2003 Significant New Alternatives Policy
Program Submission to the United States Environmental Protection Agency,
April 2003.

National Institute for Occupational Safety & Health. NIOSH Pocket Guide
to Chemical Hazards. DHHS (NIOSH) Publication No. 97-140. Washington,
D.C. U.S. Government Printing Office, 1997. 168

 

Mallinckrodt Chemicals and JT Baker Inc.  1999.  Material Safety Data
Sheet for Potassium Nitrate.  MSDS Number P5950. November.

U.S. 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.

1U.S. 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.

 As described by the CDC (1997), a particulate removing respirator
filters out dust, fibers, fumes and mists by filtering, absorbing,
adsorbing, or causing a chemical reaction with the contaminants as they
pass through the respirator canister or cartridge.  

 If workers must enter the space before the discharged particles have
settled and the gases released have dissipated, then workers are
required to wear chemical suits, gloves, goggles, and SCBA.  

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September 6, 2006

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