Final—October 9, 2014 

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Significant New Alternatives Policy Program 

Fire Extinguishing and Explosion Prevention Sector 

Risk Screen on Substitutes for Total Flooding Systems in Normally Occupied Spaces 

Substitute: Powdered Aerosol D (Stat-X®) 

This risk screen does not contain Clean Air Act (CAA) Confidential Business Information (CBI) 

and, therefore, may be disclosed to the public. 

1. 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 ODSusing 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 extinguishing and 

explosion protection sector (hereinafter referred to as the Background Document, EPA 1994a). This risk 

screen discusses the potential human health and environmental risks posed by Powdered Aerosol D or 

Stat-X® Aero-K® Fire Suppressant (hereinafter referred to as Stat-X®) when used as a flooding agent in 

normally occupied spaces. There are several applications for this technology including the protection of 

selected spaces in aircraft, ships and vehicles (including commercial, civilian, and military types), such as 

vessel engine rooms and machinery spaces (Fireaway, Inc. 2013a). The Stat-X® system presently has 

EPA SNAP approval for use as a total flooding fire extinguishing system alternative in normally 

unoccupied areas. Table 1 details the composition of the proposed substitute prior to activation. 

Table 1: Composition of Stat-X® Fire Suppression Aerosol Generator Prior to Activation 

Component Chemical Formula CAS Number Concentration 

(Weight Percent) 

 

 
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Table 2 presents the post-activation products and concentrations for Stat-X® [ ] (Fireaway Inc. 2013a). 

Table 2: Post-Activation Products from a Discharge of Stat-X® Fire Suppression Aerosol Generator 

Component Chemical Formula CAS Number Concentration 

(Weight Percent)*

 

Section 2 of this report summarizes the results of the risk screen for the proposed substitute for use in 

normally occupied spaces. The remainder of the report is organized into the following sections: 

 Section 3: Atmospheric Assessment 

 Section 4: Potential Health Effects 

 Section 5: Occupational Exposure Assessment 

 Section 6: End-Use Exposure Assessment 

 Section 7: General Population Assessment 

 Section 8: Volatile Organic Compound Assessment 

 Section 9: References 

2. SUMMARY OF RESULTS 

Powdered Aerosol D (Stat-X®) is recommended for SNAP approval as a total flooding agent in normally 

occupied spaces. EPA’s risk screen indicates that the use of the proposed substitute is not expected to 

pose a significant toxicity risk to personnel or the general population. It is expected that procedures 

identified in the material data safety sheet (MSDS) for Stat-X® and good manufacturing practices will be 

adhered to, and that the appropriate safety and personal protective equipment (PPE) (e.g., protective 

gloves, tightly sealed goggles, protective work clothing, and particulate-removing respirators with NIOSH 

type N95 or better filters)1

 consistent with OSHA guidelines will be used, as applicable, during 

manufacture and disposal of total flooding systems using Stat-X®. Because units are to be installed in 

normally occupied spaces that are equipped with features such as a system-isolate switch and cross-zone 

detection system, risk of accidental activation of a Stat-X® generator while persons are present in the 

protected space is not likely. Additionally, warning of pending discharge and delay in release to ensure 

egress prior to activation of the agent is required to reduce the risk of exposure. EPA’s risk screen also 

indicates that the use of the proposed substitute will be less harmful to the atmosphere than the continued 

use of Halon 1301 and substitutes used in this sector, such as HCFC Blend A, HFC-227ea, and HFC-125, 

as it is less harmful to the ozone layer, has lower climate impact, and a shorter atmospheric lifetime. StatX®’s contributions to volatile organic compound (VOC) emissions is not significant, as all of its 

components following activation are exempt under CAA regulations (40 CFR §51.100(s)). 

 

 

1 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. A list of available NIOSH-approved N95 disposable particulate respirators can be found here: 

http://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/n95list1.html
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3. ATMOSPHERIC ASSESSMENT 

This section presents an assessment of the potential risks to atmospheric integrity posed by the use of 

Stat-X® as a total flooding fire extinguisher in normally occupied areas. According to the submitter, StatX® does not contain any halogens so its ozone-depleting potential (ODP) is zero. [ ] 

The proposed substitute is substantially less harmful to the ozone layer, has lower climate impact, and a 

shorter atmospheric lifetime compared to Halon 1301. In addition, the pre- and post-activation 

constituents of Stat-X® have lower climate impacts and shorter atmospheric lifetimes than those predicted 

for other substitutes examined in the Background Document, as well as a commonly utilized substitutes. 

Thus, EPA believes that use of Stat-X® would result in substantially less harm to ozone layer than the 

continued use of ODS and commonly used ODS substitutes, and will also have a lesser impact on the 

climate system. 

 

Table 3: Atmospheric Impacts of Stat-X® Compared to Other Flooding Agents 

Chemical ODP GWP ALT (years) 

Proposed Substitute

 

Other Flooding Agents 

Halon 1301 15.9d 7,140e 65e

HCFC Blend Af 0.035d 1,546e NAg 

HFC-227ea 0 3,220e 34.2e

HFC-125 0 3,500e 29e

a [ ] 

b [ ] 

c [ ] 

d WMO (2010) 

e IPCC 4th Assessment Report (Forster et al. 2007) f

 HCFC Blend A is a blend consisting of HCFC-123 (4.75%), HCFC-22 (82%), HCFC-124 (9.5%), and D-limonene (3.75%). 

g 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). 

 

4. DISCUSSION OF END-USE SCENARIOS 

Stat-X® is proposed for use as a total flooding fire extinguishing agent in normally occupied spaces. There 

are several applications for this technology including the protection of selected spaces in aircraft, ships 

and vehicles (any of which might include military versions), such as vessel engine rooms and machinery 

spaces (Fireaway, Inc. 2013a). Prior to activation, the Stat-X® formulation (see Table 1) is contained as a 

solid disk of chemicals in a double-walled, insulated, and hermetically-sealed steel container. [ ] In 

response to heat and lack of oxygen, the formulation undergoes a chemical reaction; once the Stat-X® 

system is activated, it generates and discharges a homogenous mixture of gas and particulates into a space 

containing a fire hazard or directly on the hazard itself, extinguishing the fire. 

In normally occupied spaces, the Stat-X® aerosol generators are either manually or electrically activated. 

The electrical units are activated by an electrical signal from a UL-approved releasing panel and also 

possess a manual release system.2

 The manual activation option serves as a back-up method in the event 

there is a failure in the electrical activation controls and as the primary option in spaces where automatic 

activation is specifically prohibited, such as in machinery spaces and cargo pump rooms aboard merchant 

 

2 Note that safeguards against false activation are part of the testing and requirements for the UL-approved detection and 

releasing panels utilized in the system. 
Final—October 9, 2014 

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ships according to the International Maritime Organization (IMO) (Fireaway Inc. 2013a). Manual 

activation systems ensure that all personnel have exited the space prior to activation. Stat-X® generators 

range in charge size from 30 grams to 2,500 grams and are installed singly or in multiples as required by 

the volume and configuration of the protected space in addition to the hazard rating. In accordance with 

the UL listing, the final design concentration of Stat-X® is 97 g/m3

 for Class A fires and 67 g/m3 for Class 

B fires.3 Actual concentrations will not normally exceed 100 g/m3. [ ] 

[ ] This risk screen discusses the potential risk of occupational exposure during installation and servicing 

and end-use exposure based on this worst-case scenario maximum concentration. 

5. POTENTIAL HEALTH EFFECTS 

Because the fire suppressant precursors are prepared in tablets that are non-reactive and do not crumble or 

flake, there is no concern with regard to inhalation or ingestion of the pre-activation compounds. The 

post-activation products that might be released in the event of an accidental discharge are listed in Table 

2, above. The hazardous gaseous components of Stat-X® [ ] are not present in great enough concentrations 

to pose a significant toxicity risk. If the generator is activated, possible exposure to the aerosol 

suppression agent may cause temporary, mild irritation of the mucous membrane. If eye or skin contact 

occurs, end users should flush eyes with water or wash skin with soap and water. According to the 

submitter, laboratory studies have concluded that exposure to Stat-X® fire suppressant for approximately 

15 minutes has no significant observable respiratory, dermal or ocular effects. 

The discharge of the aerosol, however, does result in a reduction of visibility in the protected space due to 

the uniform distribution of the particulate generated (Fireaway, Inc. 2013a). NFPA 20104

 requires that a 

warning of pending discharge and delay in release is required to minimize the possibility of a system 

discharge when personnel are still present in the protected space. This standard also requires a supervised 

disconnect switch to avoid unwanted discharge of an aerosol system during maintenance, which the 

submitter indicates is installed on the releasing circuit and at the entrance to the protected space 

(Fireaway, Inc. 2013b). In addition, EPA recommends that cross-zone detection systems and abort 

switches located near an exit from the protected space are employed. 

6. OCCUPATIONAL EXPOSURE ASSESSMENT 

The potential for personnel exposure during manufacture, installation and servicing are examined in this 

section. To evaluate occupational exposure, EPA has evaluated the risks associated with discharge 

scenarios which are assumed to occur accidentally and not as the result of a fire. Therefore, the 

recommendations made in this section shall only apply to accidental releases of the Stat-X® compound. 

6.1. Occupational Exposure during Manufacture 

As described by the submitter, there is limited exposure to the product during manufacturing. The 

chemicals in the Stat-X® formulation are pressed into a solid disk and then shipped to the Stat-X®

manufacturing facilities under U.S. Department of Transportation regulations.5

 The agent, in its pressed 

form, is flammable with an auto-ignition temperature of 300°C. However, upon receipt, it is contained 

within a double-walled, insulated, and hermetically sealed steel container. [ ] Therefore, exposure to 

 

3 Class A fires involve ordinary combustibles, such as paper, trash, some plastics, wood and cloth. A rule of thumb is if it leaves 

an ash behind, it is a Class A fire. Class B fires involve flammable gases or liquids, such as propane, oil and gasoline (OSHA 

2009). 

4 NFPA 2010: Standard for Fixed Aerosol Fire-Extinguishing Systems (NFPA 2010) 5 Potassium Nitrate is a Hazard Class 5.1, UN Number UN1486, Packing Group III. 
Final—October 9, 2014 

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flame and risk of ignition is unlikely. Because the constituents of Stat-X® arrive at the manufacturing 

facility pressed into solid disks, exposure is only likely when chemicals are processed into disks. 

Employees responsible for chemical processing should wear the appropriate PPE, such as protective 

gloves, tightly sealed goggles, protective work clothing, and particulate-removing respirators with NIOSH 

type N95 or better filters consistent with OSHA guidelines. Production facilities are ISO 9001:2008 

certified and qualified to MIL procedures (Gross 2006; Fireaway, Inc. 2003). Additionally, the 

manufacturing space should be well ventilated with a local exhaust system, and an eye wash fountain and 

quick drench facilities must be close to the production area. In the worst case scenario of accidental 

activation of the Stat-X® generator, workers should immediately vacate the premises and follow the first 

aid guidelines listed in the MSDS. EPA believes if these exposure controls are employed and the 

appropriate occupational safety guidelines are adhered to, significant occupational exposure during 

manufacture of Stat-X® is not expected to occur. 

6.2. Occupational Exposure during Installation and Servicing 

Exposure to Stat-X® is not likely during installation or servicing of Stat-X® generators as the formulation 

is in solid form and is contained within a double-walled, hermetically sealed metal cylinder. As indicated 

by the submitter, the risk of accidental activation of a Stat-X® generator while personnel are present in the 

protected space is highly unlikely if proper procedures are followed. The electrical units, which would be 

installed in normally occupied spaces, are equipped with a system-isolate switch (located outside the 

protected area) that, when activated with a key, inhibits automatic activation of the system while the fire 

detection and alarm systems continue to function. However, in the situation where the system could be 

activated while persons are present in the protected space, the activation system normally incorporates a 

cross-zone detection system and time delay. Upon detection in one zone, a warning strobe sounds and a 

30-second time delay occurs prior to system release when the detection system is activated in a second 

zone. This time delay and two-zone alarm system allows any personnel present in the protected space 

without the system-isolate switch turned on to exit prior to system discharge. Proper instructions on 

system isolation included in both the design and owner’s manuals for the Stat-X® systems should be 

adhered to. 

In the event of discharge, accidental or otherwise, protective gloves, tightly sealed goggles, protective 

work clothing, and particulate-removing respirators with NIOSH type N95 or better filters should be worn 

if entering the normally occupied space after the event (Fireaway, Inc. 2013a). As indicated by the 

submitter, 97 percent of the particulate matter is less than 5 μm, and 76 percent is less than 3 μm, making 

the particulate matter highly respirable and able to reach the extrathoracic, tracheo-bronchial, and 

pulmonary regions of the respiratory system (Fireaway, Inc. 2003; EPA 1994b). Based on the design 

concentration and percent of particulate matter discharged, the levels of respirable dust could reach 67.9 

g/m3

, far exceeding ACGIH’s limit of 10 mg/m3 for total inhalable dust and 3 mg/m3 for the respirable 

fraction (ACGIH 2006). Personnel should not enter the space following the discharge until all particles 

have settled and/or ventilated. Based on the particle size distribution information provided by the 

submitter and predicted settling rates of aerosol particulates in still air from the Institute of Medicine, the 

majority of the particles (76 percent), which are between 1 and 3 μm, would take 4 to 8 hours to settle just 

one meter (Institute of Medicine 2000). Therefore, it is likely that the majority of the particles released 

will be released from the space during ventilation. 

7. END-USE EXPOSURE ASSESSMENT 

Stat-X® is not expected to pose significant risk to end-users when used as a total flooding agent in 

normally occupied spaces. According to the Stat-X® Design, Installation, and Maintenance Manual and in 

accordance with NFPA 2010, all Stat-X® systems installed in occupiable spaces must incorporate a pre-
Final—October 9, 2014 

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discharge alarm and minimum 30-second time delay to allow for personnel egress prior to system 

discharge. Depending on the Stat-X® generator model, the discharge rate is typically in the range of [ ], 

with the system discharging entirely within a range of 7-37 seconds. Stat-X® generators range in charge 

size from 30 grams to 2,500 grams and are installed singly or in multiples as required by the volume and 

configuration of the protected space in addition to the hazard rating. 

[ ] According to the submitter, laboratory studies have concluded that exposures to Stat-X® fire 

suppressant for approximately 15 minutes are well within the limits set by NIOSH, which is demonstrated 

in Table 4. [ ] 

[ ] In the event of exposure to Stat-X®, individuals are expected to follow the instructions prescribed in 

the proposed substitute’s MSDS. However, when individuals follow the proper precautionary measures 

described in Section 4 and Section 5.2, risk of exposure and irritation will be unlikely. 

Table 4: End-Use Exposure Assessment of Gaseous Post-Activation Stat-X® Products 

Product Constituent 15-min TWA Exposure (ppm) 

Design Concentration: 100 g/m3 

Short Term (15-min) 

Exposure Limits (ppm) IDLH Level (ppm) 

8. GENERAL POPULATION EXPOSURE 

This section screens potential risks to the general population from exposure to releases of Stat-X® to 

ambient air, surface water, and solid waste. Stat-X® is not expected to cause a significant risk to human 

health in the general population when used as a flooding agent in normally occupied spaces. The only 

consumer exposure to Stat-X® will be during discharge of the generators. When the precautionary 

measures described in the proposed substitute’s MSDS and Section 4 and Section 5.2 of this risk screen, 

no adverse health effects are expected. 

8.1. Ambient Air 

Stat-X® is not expected to pose a risk to human health in the general population in ambient air 

concentrations. All manufacturing occurs in a facility with a closed ventilation system and in the center of 

a square mile rural site (Fireaway, Inc. 2013a). Therefore, release of Stat-X® to ambient air is likely to be 

minimal, and is not expected to be a safety concern.

8.2. Surface Water 

None of the pre- or post-activation constituents of Stat-X® are listed as priority pollutants or toxic 

pollutants under the Clean Water Act, except for [ ] (toxic pollutant) which is produced in insignificant 

quantities (0.009%). However, three of the post-activation constituents [ ] are listed as hazardous 

substances under the Clean Water Act with reporting quantities of [ ] respectively. However, given that 

the maximum capacity of the Stat-X® generator is 2,500 grams, none of these constituents will exist in in 

quantities approaching their respective reporting quantities. Additionally, disposal of Stat-X® aerosol 

generatorsis subject to local, state, and federal regulations, which ensure that releases of Stat-X®

constituents and water contaminated with Stat-X® constituents are not be dumped into sewers, on the 

ground, or into any body of water, but rather taken to a wastewater treatment facility or disposed of 

properly. Therefore, Stat-X® is not expected to pose a significant risk to human health or the environment 

when proper disposal procedures are followed. 
Final—October 9, 2014 

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8.3. Solid Waste 

None of the constituents of Stat-X® [ ] are considered to be hazardous waste under EPA regulations 

implementing the Resource Conservation and Recovery Act. During post-activation clean-up procedures, 

clean-up residues should be disposed of in accordance with requirements appropriate for those materials, 

as outlined in the proposed substitute’s MSDS and local, state, and federal regulations. EPA believes that 

when these disposal requirements are met, Stat-X® does not pose a significant risk to the general 

population or environment. 

9. VOLATILE ORGANIC COMPOUND (VOC) ANALYSIS 

The post-activation constituents of Stat-X® [ ] are exempt from the definition of volatile organic 

compound (VOC) under CAA regulations (40 CFR § 51.100(s)).Therefore, environmental impacts from 

the release of Stat-X® as a VOC are not a significant concern. 
Final—October 9, 2014 

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10. REFERENCES 

ACGIH. 2004. The Documentation of the Threshold Limit Values and Biological Exposure Indices. 

American Conference of Governmental Industrial Hygienists. Available at: www.acgih.org. 

ACGIH. 2005. Guide to Occupational Exposure Values. American Conference of Governmental 

Industrial Hygienists. 

ACGIH. 2006. Threshold Limit Values for Chemical Substances (TLV®-CS). Dennis Casserly, TLV®-

CS Committee, University of Houston at Clear Lake. American Conference of Governmental Industrial 

Hygienists. Available online at: http://www.acgih.org/tlv/03_TLV-CS-Update_AIHce06.pdf. 

CDC. 1997. Respiratory Protection Program Manual. Office of Health and Safety, Centers for Disease 

Control and Prevention. January 1997. 

Folland, C.K., T.R. Karl, J.R. Christy, R.A. Clarke, G.V. Gruza, J. Jouzel, M.E. Mann, J. Oerlemans, M.J. 

Salinger and S.-W. Wang, 2001: Observed Climate Variability and Change. In: Climate Change 2001: 

The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the 

Intergovernmental Panel on Climate Change [Houghton, J.T., Y. Ding, D.J. Griggs, M. Noguer, P.J. van 

der Linden, X. Dai, K. Maskell, and C.A. Johnson (eds.)]. Cambridge University Press, Cambridge, 

United Kingdom and New York, NY, USA. Available online at: 

http://www.grida.no/climate/ipcc_tar/wg1/pdf/wg1_tar-front.pdf 

Forster, P., V. Ramaswamy, P. Artaxo, T. Berntsen, R. Betts, D.W. Fahey, J. Haywood, J. Lean, D.C. 

Lowe, G. Myhre, J. Nganga, R. Prinn, G. Raga, M. Schulz and R. Van Dorland. (2007). Errata. In: 

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http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-errata.pdf. 

Fireaway Inc. 2003. Stat-X® Aero-K Condensed Aerosol System for Use in Normally Unoccupied Spaces 

in Fire Suppression Sector. Significant New Alternatives Policy Program Submission to the U.S. 

Environmental Protection Agency. April 2003. 

Fireaway Inc. 2013a. Stat-X® Aero-K Condensed Aerosol System for Use in Normally Occupied Spaces 

in Fire Suppression Sector. Significant New Alternatives Policy Program Submission to the U.S. 

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Fireaway Inc. 2013b. Response to Incompleteness Letter for Stat-X® Aero-K Condensed Aerosol System 

for Use in Fire Suppression Sector. July 15, 2013. 

Gross, Marc. 2006. Personal communication from Marc Gross, Fireaway LLC to Bella Maranion, EPA. 

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Medicine National Academy Press. Washington, DC. 
Final—October 9, 2014 

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National Academy of Sciences (NAS). 2007. Acute Exposure Guideline Levels for Selected Airborne 

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U.S. EPA. 2012. Acute Exposure Guidelines (AEGLs) Definitions. Available online at: 

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WHO (World Health Organization). 1998. Concise International Chemical Assessment Document 5 – 

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