Significant New Alternatives Policy Program
Fire Extinguishing and Explosion Prevention Sector
Risk Screen on Substitutes for Halon 1301
Total Flooding Systems in Normally Unoccupied Spaces
      Substitute: Dry Sprinkler Powdered Aerosol (DSPA) Fixed Generators


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 two decades, 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, administers the Significant New Alternatives Policy (SNAP) Program, which identifies acceptable and unacceptable substitutes for ODS in specific end-uses based on assessment of their health and environmental impacts.

EPA's decision on the acceptability of a substitute is based 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-use applications 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 (EPA 1994) (hereinafter referred to as the Background Document). This risk screen discusses the potential human health and environmental risks posed by Dry Sprinkler Powdered Aerosol (DSPA) generator when used as a flooding agent in normally unoccupied spaces as a replacement for Halon 1301. The proposed substitute is anticipated to be used for Class A (ordinary combustibles), B (flammable liquids and gases), and C (electrical) fires, pending UL approval. The reader is referred to the Background Document for the methodologies and assumptions used to conduct this risk screen. 

DSPA generators contain a solid material in pellet form that aerosolizes upon activation.  The DSPA fixed generators are designed to suppress fires as fixed installations in enclosed areas in all industrial and commercial structures and in the transport sector (trains, trucks, cars, and ships) in normally unoccupied spaces.  The DSPA fixed generators include several models. Table 1 presents the composition of the proposed substitute, prior to activation.

          Table 1: Composition of DSPA Generator, Prior to Activation
                             Constituent (Solids)
                               Chemical Formula
                                     CAS #
                                Weight Percent
Potassium nitrate
                                     KNO3
                                   7757-79-1
                                       
Phenol formaldehyde resin
                                   C13H12O2
                                   9003-35-4
                                       
Cyanoguanidine
                                    C2H4N4
                                   461-58-5
                                       


Table 2 presents the composition of the post-activation products of the proposed substitute. 
                                       
            Table 2: Composition of DSPA Generator, Post-Activation
                                Solid Particles
                               Chemical Formula
                                     CAS #
                                Weight Percent
Potassium carbonate
                                     K2CO3
                                   584-08-7
                                       
Ammonium bicarbonate
                                    NH4HCO3
                                   1066-33-7
                                       
Potassium bicarbonate
                                     KHC03
                                   298-14-6
                                       
Other potassium compounds
                                       -
                                       -
                                       
                                     Gases
                               Chemical Formula
                                     CAS #
                                Weight Percent
Nitrogen
                                      N2
                                   7732-18-5
                                       
Carbon dioxide
                                      CO2
                                   124-38-9
                                       
Water 
                                      H2O
                                   7727-37-9
                                       
Other Impurities
                                       -
                                       -
                                       
  Ammonia
                                      NH3
                                   7664-41-7
                                       
  Hydrogen cyanide
                                      HCN
                                    74-90-8
                                       
  Carbon monoxide
                                      CO
                                   630-08-0
                                       
  Nitrous oxide
                                      NO
                                  10102-43-9
                                       
Total mass
                                       -
                                       -
                                    100.00

Section 2 of this risk screen summarizes the results of the risk screen for the proposed substitute.  The remainder of the risk screen is organized into the following sections:

   * Section 3: Atmospheric Assessment; 
   * Section 4: Potential Health Effects
   * Section 5: Occupational Exposure Assessment;
   * Section 6: Exposure at End-Use; 
   * Section 7: General Population Exposure Assessment; 
   * Section 8: Volatile Organic Compound Assessment; and
   * Section 9: References.
SUMMARY OF RESULTS
DSPA fixed generators are recommended for SNAP approval as a flooding agent in normally unoccupied spaces. Given that proper training will be provided to personnel and that appropriate personal protective equipment (PPE) and proper procedures according to the MSDS (including provisions of adequate ventilation) will be used during manufacturing and disposal activities, no significant risks to workers or the general population is anticipated. In addition, 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 and than other substitutes used in this sector, such as HFC-227ea and HFC-125.

Limited end-use, occupational exposure and hazard analyses were conducted since this proposed substitute is recommended only for use in normally unoccupied areas.  Likewise, no consumer exposure and risk screening analyses were conducted since this proposed substitute is intended only for total-flooding applications, which are not used by consumers.  Information provided by the submitter, summarized in Section 5, indicates that DSPA fixed generators are not likely to pose a significant risk to workers during the manufacture, installation, maintenance, and cleanup activities.  
ATMOSPHERIC ASSESSMENT
This section presents an assessment of the potential risks to atmospheric integrity posed by the use of DSPA fixed generators as a flooding agent. The ozone depletion potential (ODP), global warming potential (GWP), and atmospheric lifetime (ALT) of the proposed substitute are presented in Table 3. Pre-activation, DSPA generator contains no Class I or Class II ODS, nor any compounds with measured global warming potential (GWP). Some of the post-activation products and impurities (carbon dioxide, carbon monoxide, and nitrous oxide) have a measurable atmospheric impact; however, only very small concentrations of those constituents are formed upon activation of DSPA generators and the comparative atmospheric impact (e.g., ODP and GWP values of these compounds) to Halon 1301, HCFC Blend A (NAF S III(R)), HFC-227ea, and HFC-125 is much lower. Therefore, the use of DSPA generator will be less damaging to the atmosphere than continued use of Halon 1301, HCFC Blend A, or other substitutes.

                                       
                                       
                                       
                                       
                                       
                                       
                                       
Table 3. Atmospheric Impacts of DSPA Generator Components Compared to Halon 1301 and Other Flooding Agents
                          Pre-Activation Constituents
                                      ODP
                                      GWP
                                      ALT
Potassium nitrate
                                       0
                                       0
                                       0
Phenol formaldehyde resin
                                       0
                                       0
                                       0
Cyanoguanidine
                                       0
                                       0
                                       0
                           Post-Activation Products
                                      ODP
                                      GWP
                                      ALT
Potassium carbonate
                                       0
                                       0
                                       0
Ammonium bicarbonate
                                       0
                                       0
                                       0
Potassium bicarbonate
                                       0
                                       0
                                       0
Other potassium compounds
                                       0
                                      NA
                                      NA
Nitrogen
                                       0
                                       0
                                       0
Carbon dioxide
                                       0
                                       1
                                   5-200[a]
Water 
                                       0
                                       0
                                       0
Ammonia
                                       0
                                     0[b]
                                  Few days[b]
Hydrogen cyanide
                                       0
                                       0
                                 5-6 months[d]
Carbon monoxide
                                       0
                                     3[e]
                               Several months[e]
Nitrous oxide
                                   0.017[b]
                                    298[c]
                                    114[c]
Halon 1301
                                     16[b]
                                   7,140[c]
                                     65[c]
HCFC Blend A (NAF S III(R))
                                   0.036[f]
                                    1,444 f
                                     NA[g]
HFC-227ea
                                       0
                                   3,220[c]
                                    34.2[c]
HFC-125
                                       0
                                   3,500[c]
                                     29[c]
[a] IPCC 3[rd] Assessment Report (Houghton et al.2001)
[b]Scientific Assessment of Ozone Depletion 2010 (WMO 2011)
[c] IPCC 4th Assessment Report (Forster et al. 2007)
[d] JACC (2007) 
[e] MacCarty, et. al. (2007)
[f] Safety Hitech (2012)
[g] NA= not available. Atmospheric lifetimes are not given for blends because the components separate in the atmosphere. The ALT for HCFC-123 is 1.3 years, HCFC-22 is 12 years, HCFC-124 is 5.8 years, and D-limonene ranges from less than a minute to a few hours (IPCC 4th Assessment Report [Forster et al. 2007] and WHO 1998).
POTENTIAL HEALTH EFFECTS
According to the MSDS, exposure to DSPA generator may result in irritation if inhalation, ingestion, skin contact, or eye contact occurs. According to the MSDS for DSPA generator, if the contents of DSPA generator are inhaled, person(s) should be immediately removed and exposed to fresh air. In accordance with the MSDS, EPA further recommends that if breathing is difficult, person(s) be given oxygen, provided a qualified operator is present, and medical attention be sought. Rescuers should not attempt to retrieve victims of exposure to DSPA generator without adequate PPE. A NIOSH/CDC-approved N99 respirator should be worn to retrieve victims of exposure to DSPA generator. If DSPA generator is activated, exposure to aerosol suppression agent through inhalation may cause temporary, mild irritation of mucous membrane. If ingestion occurs, person(s) should wash out mouth with plenty of water and not induce vomiting. Medical advice should be sought. In case of dermal exposure, the MSDS recommends that person(s) immediately wash the affected area with water and remove all contaminated clothing. If ocular exposure to DSPA generator occurs, contact lenses, if worn by exposed person(s), should be removed. The MSDS for DSPA recommends that person(s) immediately flush the eyes, including under the eyelids, with copious amounts of water for 15 minutes (DSPA.nl 2012b). When the PPE recommendations outlines in the MSDS for DSPA generators and Section 5 of this risk screen are followed, these potential health effects are unlikely to occur. 
OCCUPATIONAL EXPOSURE ASSESSMENT
The potential for occupational exposure to constituents in DSPA generator are examined in this section.  Specific guidance has been included regarding precautionary measures, PPE, settling rates and re-entry time for occupational exposure during manufacture, installation, maintenance, and cleanup. The use of the exposure controls and adherence with the appropriate occupational safety guidelines discussed in the following sections and the MSDS for DSPA are sufficient to ensure that the manufacture, installation, maintenance, and cleanup of DSPA does not pose a significant risk to human health. Further, the generator unit consists of solid blocks of DSPA constituents that are not friable and are contained in rigid steel casing; as a result, workers have no direct contact with the proposed substitute, and the material is prevented from coming into contact with combustible materials during normal transport, storage and handling. In addition, exposure to DSPA generator's raw materials during manual processing at manufacture is expected to be in the solid form, with any possible inhalation or dermal exposures considered to be negligible (DSPA.nl 2011a). Further, because safety and precautionary measures listed in the MSDS for the proposed substitute are to be followed, excessive exposure to workers is unlikely. For measures designed to minimize the hazards associated with a specific constituent, the constituent's MSDS should be referenced. 
   0.1.       Occupational Exposure during Manufacture
DSPA generator is not expected to pose a significant risk to workers during manufacture due to the use of an automated production process.  These workers wear PPE, including suits, safety glasses, and respirators.  The entire manufacturing space is ventilated with a local exhaust system to reduce airborne exposure of pyrotechnical compound.  

Currently, there are not any United States-based manufacturing facilities for this proposed substitute and none are planned.  The final product available in United States is the rigid steel case containing solid blocks of the extinguishing material. If production were to occur in the United States, the proposed substitute's MSDS should be referenced.
   0.2.       Occupational Exposure during Installation and Maintenance
The extinguishing application density of DSPA generators systems is 50 g/m[3] for all models.  Therefore, assuming a safety factor of 1.3, the design application density is 65 g/m[3].  The post-activation products include both gaseous and particulate components, which could cause slight respiratory irritation if inhaled (DSPA.nl 2011b, EPA 1994).  

Occupational exposure may occur during installation and maintenance of DSPA generators if an accidental deployment of a fixed generator occurs. In the event of an accidental discharge, the room should be immediately evacuated and the instructions listed in the MSDS for DSPA generator should be followed (DSPA.nl 2012b). Worker exposure is unlikely because NIOSH/CDC-approved N99 respirator is expected to be worn. 
   0.3.       Post-activation Cleanup
After DSPA generator is activated, the aerosol is released into the air significantly reducing visibility until 30 to 40 minutes, when the post-activation particles settle down.  According to the submitter and the MSDS for DSPA generators, workers should not enter the space following discharge until all particles have settled and been ventilated and the gases released by the system have dissipated.  If workers must enter the space before it has been ventilated, they should wear protective clothing, goggles, and NIOSH/CDC-approved N99 respirator.  It is unlikely that anyone would enter the space inadvertently after discharge, as visibility in the space would be significantly reduced, and signage (indicating that the area should not be entered after discharge until ventilation) should be present at the entrances and exits of all protected spaces.  After 2 hours the air should be refreshed using a ventilator. The settled aerosol particles can be cleaned up as soon as the structure is totally ventilated or after 24 hours, whichever occurs first (DSPA.nl 2011c).  In accordance with the MSDS, settled particles are to be collected by hand (e.g., with a dustpan and duster) or with a vacuum cleaner.   The waste should be collected in suitable drums for disposal according to federal, state, and local regulations and the area should be washed clean with plenty of water.  After activating the generator, slight irritation may occur to the skin due to an increase of the pH value. Safety glasses and a NIOSH/CDC-approved N99 respirator, in accordance with 42 CFR Part 84, should be worn by individuals participating in cleanup procedures because cleanup operations are likely to result in the re-circulation of dust particles. Workers cleaning a major spillage should wear personal protective clothing (suitable gloves and filter mask FFP-2 if dust is formed) DSPA.nl 2011c).  By adhering to safety guidelines mentioned above and in Section 4, the potential for excessive worker exposures to DSPA during post-activation cleanup will be unlikely.
EXPOSURE AT END-USE
DSPA generator is not expected to pose significant risk to end-users when used as a flooding agent in normally unoccupied spaces. For total flooding applications in normally unoccupied spaces, exposure at end-use is only evaluated in the event of an accidental discharge rather than discharge in the occurrence of a fire.  In the event of an accidental discharge at end-use, all personnel should wear NIOSH/CDC-approved N99 respirator and allow adequate time for the aerosol particles to settle and the air to be ventilated before re-entering the protected space, as outlined in section 5.2.  Individuals responsible for cleaning up after inadvertent release of DSPA are expected to follow the cleanup procedures outlined in Section 5.3.  
GENERAL POPULATION EXPOSURE ASSESSMENT
DSPA generator is not expected to cause a significant risk to human health in the general population when used as a flooding agent in normally unoccupied spaces. The generator consists of solid blocks that are not friable and are contained in rigid steel casing that would not release into the environment unless activated. As discussed in the Background Document, the physicochemical properties of the majority of halon substitutes make it unlikely that the substitutes would be released to surface water as a result of use. In the case of DSPA generator, it is expected that all of the constituents would rapidly aerosolize during expulsion from the container and then settle as a dust on surfaces within the protected space (as opposed to becoming airborne and settling on a nearby stream). After settling, cleanup would involve washing or rinsing of surfaces. Because all federal, state, and local regulations pertaining to waste disposal are followed, no release to the environment is expected. 

VOLATILE ORGANIC COMPOUND ASSESSMENT
Of the pre- and post-activation constituents of DSPA generator, hydrogen cyanide (a post-activation product) is the only compound considered to be a VOC that has not been exempted as a volatile organic compound (VOC) under the CAA (40 CFR 51.100(s)). Phenol formaldehyde resin (a pre-activation constituent) is also considered a VOC, but is a solid, and therefore not a concern. All remaining constituents are not considered to be VOCs. Hydrogen cyanide constitutes a very small percent of the post-activation products by weight. In general, VOC emissions should be sufficiently controlled through regulations and standard industry practices. VOC emissions from the production of total flooding systems charged with DSPA are controlled through standard industry practices, and as such, emissions from manufacture of units are likely to be minimal.  An assessment was performed to compare the annual VOC emissions from use of DSPA in total flooding systems produced in one year to other anthropogenic sources of VOC emissions.  Assuming that 100 percent of DSPA produced in one year were to be used in fire occurrences and thus released to the atmosphere (extremely unlikely), only 0.04 MT of VOCs would be emitted, which is approximately equal to 8.6x10[-]6 percent of the annual VOC emissions caused by fires, or only about 1.5x10[-]6 percent of annual VOC emissions caused by highway vehicles (a major source of hydrogen cyanide emissions).  In order to estimate more realistic release rates, data for fire occurrences where DSPA may be used would be needed.  In the absence of this data, a 100 percent release assumption was made. Even at this unlikely release rate, the VOC emissions from use of DSPA are several orders of magnitude lower than other anthropogenic VOC emissions; therefore, the environmental impacts of these VOCs are not considered a significant risk. 



REFERENCESDSPA.NL. 2011a.  SNAP Submission to EPA for DSPA generator.  April 28, 2011.
DSPA.nl . 2011b.  "Response to Incomplete SNAP Submission for DSPA generator." July 28, 2011.
 DSPA.nl. 2011c.  "Response to Incomplete SNAP Submission for DSPA generator." September 7, 2011.
DSPA.nl. 2012a. "Response to Incomplete SNAP Submission for DSPA generator." May 16, 2012.
DSPA.nl. 2012b. "Material Safety Data Sheet: DSPA `Fixed Installation' Generator." March 27, 2012.
EPA 1994. "Risk Screen on the Use of Substitutes for Class I Ozone-depleting Substances:  Fire Extinguishing and Protection (Halon Substitutes)," U.S. Environmental Protection Agency, March 1994.
EPA 2008. 2005 National Emissions Inventory Data & Documentation. Inventory Data: 42 Category Summaries. Last updated 6 July 2010. Accessed 20 September 11. Available online at <http://www.epa.gov/ttn/chief/net/2005inventory.html#inventorydata>.
EPA 2009.  National Emissions Inventory (NEI) Air Pollutant Emissions Trends Data and Estimation Procedures.1970  -  2008 Average Annual Emissions, All Criteria Pollutants.  Last updated 09 June 2009. Accessed 20 September 11. Available online at <http://www.epa.gov/ttn/chief/trends/index.html#tables>. 
EPA 2011. The National Emissions Inventory. 2008 National Inventory Data. Last updated 19 July 11. Accessed 20 September 11. Available online at <http://www.epa.gov/ttn/chief/net/2008inventory.html>.
JACC (2007). Cyanides of Hydrogen, Sodium and Potassium, and Acetone Cyanohydrin (CAS No. 74-90-8, 143-33-9. 151-50-8 and 75-86-5), Volumes I and II. November 2007. Available online at:<http://www.ecetoc.org/index.php?mact=MCSoap,cntnt01,details,0&cntnt01by_category=3&cntnt01order_by=Number%20Desc&cntnt01template=display_list_v2&cntnt01display_template=display_details_v2&cntnt01document_id=125&cntnt01returnid=91>
MacCarty, Nordica, Damon Ogle, Dean Still, Dr. Tami Bond, Christoph Roden, Dr. Bryan Willson. (2007). Laboratory Comparison of the Global-Warming Potential of Six Categories of Biomass Cooking Stoves. Available online at: <http://www.scscertified.com/lcs/docs/Global_warming_full_9-6-07.pdf>

OSHA.  1999.  OSHA Technical Manual.  Department of Labor.  Occupational Safety & Health Administration.  January 20, 1999.  Available online at <http://www.osha.gov/dts/osta/otm/otm_toc.html>.
Safety Hitech, 2012. NAF S III(R) Fire Extinguishing Agent. Available online at: http://www.safetyhitech.com/en/products/naf-fire-ext-agents/naf-s-iiii

