Final -- October 10, 2014

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Significant New Alternatives Policy Program 

Refrigeration and Air Conditioning Sector

Risk Screen on Substitutes in Chillers and Industrial Process Air-Conditioning

Substitute: R-450A

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 risk screen is to supplement EPA’s Background Document on the refrigeration and air 

conditioning sector (EPA 1994) (hereinafter referred to as the Background Document). This risk screen 

evaluates the potential use of R-450A as a substitute in the chillers end-use (specifically, centrifugal, 

reciprocating, screw, and scroll chillers) and the industrial process air-conditioning end-use. Table 1 

presents the composition of the proposed substitute.

Table 1. Composition of R-450A and Potential Impurities

Constituent Chemical Formula CAS Number Concentration

(Weight Percent)a

1,1,1,2-Tetrafluoroethane (HFC-134a) CF3CH2F 811-97-2 42%

trans-1,3,3,3,-Tetrafluoro-1-propene 

(HFO-1234ze(E)) CHFCHCF3 29118-24-9 58%

Potential Impurities

Section 2 summarizes the results of the risk screen for the proposed substitute blend listed in Table 1. The 

remainder of the risk screen is organized into the following sections:

 Section 3: Atmospheric Assessment

 Section 4: Volatile Organic Compound Assessment 

 Section 5: Potential Health Effects 
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 Section 6: Flammability Assessment

 Section 7: Occupational Exposure Assessment 

 Section 8: General Population Exposure Assessment

 Section 9: References

2. SUMMARY OF RESULTS

R-450A is recommended for SNAP approval for chillers and industrial process air-conditioning. EPA's 

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

continued use of commonly used refrigerants including CFC-11, CFC-12, HCFC-22, HCFC-123, and R500 as it is less harmful to the ozone layer, has lower climate impact, and a shorter atmospheric lifetime.

Neither of the components of R-450A are subject to volatile organic compound (VOC) regulations under 

the CAA (40 CFR 51.100(s)), so environmental impact from the release of these substances is not a 

concern. It is expected that the material safety data sheet (MSDS) for R-450A and good manufacturing 

practices will be adhered to. Additionally, it is expected that the appropriate safety and personal protective 

equipment (PPE) (e.g., protective gloves, tightly sealed goggles, protective work clothing, and suitable 

respiratory protection in case of leakage or insufficient ventilation) consistent with Occupational Safety 

and Health Administration (OSHA) guidelines will be used during manufacture, installation and servicing, 

and disposal of chillers and industrial process air-conditioning using R-450A. Because chillers and 

industrial process air-conditioning systems are to be installed in locations with adequate space and/or 

ventilation in accordance with EPA recommendations and the equipment maintenance manuals for R450A in each end-use, significant toxicity risk to consumers is also unlikely. Additional safeguards, 

including specified refrigerant concentration limits (RCL) of R-450A components, are also provided by 

adherence to industry standards including American Society of Heating, Refrigerating and AirConditioning Engineers (ASHRAE) Standards 15,1 34,2

and 62.

3 Exposure at the end-use is captured in the 

occupational exposure assessment, as consumer use of chillers and industrial process air-conditioning

equipment is not anticipated. In addition, potential health risks from exposure to the proposed substitute is 

considered to be a larger concern for workers than asphyxiation,4 due to the large spaces in which these 

systems are installed and serviced. Therefore, an asphyxiation assessment was not conducted.

3. ATMOSPHERIC ASSESSMENT

This section presents an assessment of the potential risks to atmospheric integrity posed by the use of R450A in chillers and industrial process air-conditioning. The ozone depletion potential (ODP), global 

warming potential (GWP), and atmospheric lifetime (ALT) of the proposed substitute are presented in 

Table 2.

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

shorter atmospheric lifetime when compared to refrigerants currently used in these end-uses, such as CFC11, CFC-12, HCFC-22, HCFC-123, and R-500. In addition, R-450A also has lower climate impact and a 

shorter atmospheric lifetime than those predicted for other substitutes examined in the Background 

Document as well as commonly utilized substitutes HFC-134a, HFC-236fa, and R-407C. Thus, EPA 

 

1 Safety Standard for Refrigeration Systems ASHRAE Standard 15 establishes safeguards for life, limb, health, and property and 

prescribes safety requirements.

2 Designation and Safety Classification of Refrigerants ASHRAE Standard 34 is establishes a uniform system for assigning 

reference numbers, safety classifications, and refrigerant concentration limits to refrigerants. Safety classifications based on 

toxicity and flammability data are included.

3 Ventilation for Acceptable Indoor Air Quality ASHRAE Standard 62 establishes minimum ventilation rates and other measures 

intended to provide indoor air quality that is acceptable to human occupants and that minimizes adverse health effects. 

4 The oxygen deprivation limit (ODL) for R-450A is 140,000 ppm per Standard 34-2010 (Honeywell 2014a). Exposure estimates 

remain significantly below this level (see Table 6 in Section 7). 
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believes that the use of R-450A would result in substantially less harm to the climate and ozone layer than 

the continued use of ODS and commonly used refrigerants.

Table 2. Atmospheric Impacts of R-450A Components Compared to Other Refrigerants

Refrigerant Ozone Depleting Potential

(ODP)

a

Global Warming Potential

(GWP)

b

Atmospheric Lifetime in 

Years (ALT)

b

R-450A 0 601 NAc

Individual Components

HFC-134a 0 1,430 14

HFO-1234ze(E) 0 1

d 16.4 daysd

CFC-11 1.0 4,750 45

CFC-12 0.82 10,900 100

R-500

e 0.7 8,077 NAf

HCFC-22 0.13 1,810 12

HCFC-123 0.01 77 1.3

HFC-134a 0 1,430 14

HFC-236fa 0 9,810 240

R-407Cg 0 1,774 NAh

a WMO 2010 Scientific Assessment Report (2011)

b

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

c Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for HFC-134a is 14 years and 

the ALT for HFO-1234ze(E) is 10 days (IPCC 4th Assessment Report [Forster et al. 2007], Hodnebrog et al., 2013).

d Hodnebrog et al. (2013)

e R-500 is a blend consisting of CFC-12 (73.8%) and HFC-152a (26.2%). 

f Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for CFC-12 is 100 years and 

HFC-152a is 1.4 years (IPCC 4th Assessment Report [Forster et al. 2007]).

g R-407C is a blend consisting of HFC-32 (29%), HFC-125 (25%) and HFC-134a (52%).

h Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for HFC-32 is 4.9 years, the 

ALT for HFC-125 is 29 years, and the ALT for HFC-134a is 14 years (IPCC 4th Assessment Report [Forster et al. 2007]).

4. VOLATILE ORGANIC COMPOUND (VOC) ANALYSIS

HFC-134a and HFO-1234ze(E) are not volatile organic compounds (VOCs) according to CAA regulations 

(40 CFR 51.100(s)) due to their negligible photochemical reactivity. Therefore, environmental impacts 

from the release of HFC-134a and HFO-1234ze(E) as VOCs are not a concern. 

5. POTENTIAL HEALTH EFFECTS

To assess potential health risks from exposure to the proposed substitute in chillers and industrial process 

air-conditioning, EPA identified the relevant toxicity threshold values for comparison to modeled exposure 

concentrations for different scenarios. In March 2014, R-450A was submitted to ASHRAE’s Standing 

Standard Project Committee (SSPC) for inclusion in ASHRAE Standard 34 under safety group A1 with a 

refrigeration concentration limit (RCL) of 72,000 ppm. ASHRAE 34 RCLs are intended to reduce the risks 

of acute toxicity, asphyxiation, and flammability hazards in normally occupied, enclosed spaces during 

refrigerant use and protect end-users from the potential dangers of a catastrophic leak from refrigeration 

unit (ASHRAE 2010b). ASHRAE Standard 15 implements the aforementioned standard, requiring that 

“the concentration of refrigerant in an enclosed space following a complete discharge of a high-probability 

system shall not exceed the RCL” (ASHRAE 2010a). As such, this risk screen references the proposed 

RCL for R-450A in addition to the lower flammability limit, hypoxia no observed adverse effect level 

(NOAEL), and exposure limits, as an additional, conservative limit to ensure that significant exposure 

risks do not occur. 

For the occupational exposure analysis, potential risks from chronic and acute worker exposure were 

evaluated by comparing exposure concentrations to available occupational exposure limits. Potential risks 

of chronic worker exposure were evaluated using workplace guidance levels (WGL). Risks from potential 
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short-term consumer exposures were evaluated by comparing exposure concentrations to emergency 

guidance levels (EGL). In the absence of an established short-term exposure limit (STEL), acute exposure

guideline level (AEGL), or emergency response planning guideline (ERPG) for R-450A, potential shortterm, end-use exposures were evaluated on a component basis (i.e., HFC-134a and HFO-1234ze(E)).

Table 3 lists the relevant toxicity limits for R-450A and its components and is followed by Table 4, which 

provides an explanation of each toxicity limit. EPA’s approach for identifying or developing these values 

is discussed in Chapter 3 of the Background Document. 

Table 3. Exposure Limits of R-450A Components

R-450A 

Component

WGL

(Long-term Exposure)

ppm

EGL 

(Short-term Exposure)

ppm

Refrigerant Concentration 

Limit (RCL)

ppm

R-450A 880 (8-hour AEL) 2,640 (15-min STEL)a 72,000

Individual Components

HFC-134a 1,000 (8-hour WEEL)

b

8,000 (10-min AEGL-1)

8,000 (30-min AEGL-1) 50,000

HFO-1234ze(E) 800 (8-hour WEEL)

b 2,400 (15-min STEL)c NAd

NA = Not available

a Neither ACGIH nor AIHA recommend ceiling or short term exposure limits for the blend R-450A. A STEL for R-450A of 2,640 ppm was 

developed by EPA based on the 880 ppm AEL value. The STEL was estimated as three to five times the AEL, which is an established method of 

estimating a short-term exposure limit by ACGIH. [STEL] = [AEL] x 3 = 880 ppm x 3 ≈ 2,640 ppm

b Honeywell (2014a)

c Neither ACGIH nor AIHA recommend ceiling or short term exposure limits for HFO-1234ze(E). A STEL for HFO-1234ze(E) of 2,400 ppm was 

developed by EPA based on the 800 ppm WEEL value. The STEL was estimated as three to five times the AEL, which is an established method 

of estimating a short-term exposure limit by ACGIH. [STEL] = [AEL] x 3 = 800 ppm x 3 ≈ 2,400 ppm

d Although an RCL has not been proposed for HFO-1234ze(E), the recommended ATEL for HFO-1234ze(E) is 59,000 ppm (Honeywell 2014a).

Table 4. Explanation of Exposure Limit-Related Terminologya

Organization Definition

OSHA Occupational Safety and Health Administration

NIOSH National Institute for Occupational Safety and Health

ACGIH American Conference of Governmental Industrial Hygienists

AIHA American Industrial Hygiene Association

OARS Occupational Alliance for Risk Science

Exposure Limit Definition Explanation

Short-Term Exposure

RCL Refrigerant Concentration 

Limit

The RCL for a refrigerant is intended to reduce the risks of acute toxicity, 

asphyxiation, and flammability hazards in normally occupied, enclosed 

spaces. The RCL for each refrigerant is the lowest of the Acute-Toxicity 

Exposure Limit (ATEL), Oxygen Deprivation Limit (ODL), and Flammable 

Concentration Limit (FCL). Determination assumes full vaporization with 

no removal by ventilation, dissolution, reaction, or decomposition and 

complete mixing of refrigerant in the space to which it is released.

ATEL Acute Toxicity Exposure Limit The ATEL is the refrigerant concentration limit intended to reduce the 

risks of acute toxicity hazards in normally occupied, enclosed spaces 

according to ASHRAE Standard 34. The ATEL includes consideration of 

mortality, cardiac sensitization, anesthetic or central nervous system 

effects and other escape impairing effects and permanent injury. The 

ATEL is similar to the Immediately Dangerous to Life or Health (IDLH)

concentrations set by NIOSH.
Final -- October 10, 2014

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STEL Short-Term Exposure Limit A 15-minute time-weighted average (TWA) exposure that should not be 

exceeded during a workday, even if the 8-hour TWA is within the TLV–

TWA, set by ACGIH. 

AEGLb,c

Acute Exposure Guideline 

Level 1

AEGL-1 is the airborne concentration of a substance above which it is 

predicted that the general population, including susceptible individuals, 

could experience notable discomfort, irritation, or certain asymptomatic 

nonsensory effects. However, the effects are not disabling and are 

transient and reversible upon cessation of exposure. 

Acute Exposure Guideline 

Level 2

AEGL-2 is the airborne concentration (expressed as ppm or mg/m3) 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.

Acute Exposure Guideline 

Level 3

AEGL-3 is the airborne concentration (expressed as ppm or mg/m3) of a 

substance above which it is predicted that the general population, 

including susceptible individuals, could experience life-threatening health 

effects or death.

Long-Term Exposure

PEL Permissible Exposure Limit This is an 8-hour time-weighted average exposure limit set by OSHA. 

AEL Acceptable Exposure Limit The maximum 8-hour time weighted average (TWA) at which a worker 

can be exposed regularly without adverse effects.

WEEL Workplace Environmental 

Exposure Level

Developed by OARS for to protect healthy workers against acute and 

chronic health effects, this limit is based on repeated daily exposures 

over a working lifetime and averaged over an 8-hour workday. 

TLV-TWA Threshold Limit Value –TimeWeighted AverageThe TWA concentration for a conventional 8-hour workday and a 40-

hour workweek, to which it is believed that nearly all workers may be 

repeatedly exposed, day after day, for a working lifetime without adverse 

effect according to ACGIH. 

a All information in this table taken from EPA (1994) except where otherwise noted.

b EPA (2012)

c Applicable to emergency exposure periods ranging from 10 minutes to 8 hours.

According to the MSDS, exposure to R-450A may be hazardous if inhalation, skin contact, or eye contact 

with R-450A occurs. The most likely pathway of exposure is through inhalation. R-450A can cause 

symptoms of asphyxiation when present in concentrations high enough to significantly lower oxygen 

concentrations below 19.5 percent by volume, such as headaches, ringing in ears, dizziness, drowsiness, 

nausea, vomiting, depression of all senses, and also unconsciousness. Under some circumstances of overexposure (i.e., oxygen levels fall below 6 percent by volume), death may occur. 

If R-450A is 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 or irregular, 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 R-450A without adequate PPE. At a minimum, a self-contained 

breathing apparatus (SCBA) should be worn. Exposures of R-450A to the skin may cause frostbite. In the 

case of dermal exposure, the MSDS for R-450A recommends that person(s) immediately wash the affected 

area with water and remove all contaminated clothing; if frostbite occurs, bathe (not rub) the affected area 

with lukewarm, not hot, water. If water is not available, cover the affected area with a clean, soft cloth, and 

seek medical attention immediately. Exposures of R-450A to the eyes could cause eye irritation. In case of 

ocular exposure, the MSDS for R-450A recommends that person(s) immediately flush the eyes, including 

under the eyelids, with copious amounts of water for 15 minutes. 

EPA’s review of the human health impacts of this proposed substitute is contained in the public docket for 

this decision. These risks and procedures after exposure are similar for other common refrigerants. The 
Final -- October 10, 2014

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potential health effects of R-450A can be minimized by following the exposure guidelines and ventilation 

and PPE recommendations outlined in the MSDS for R-450A and this risk screen.

6. FLAMMABILITY ASSESSMENT

R-450A has been submitted to the ASHRAE SSPC 34 committee for classification as an A1 refrigerant, 

and is considered to be nonflammable (Honeywell 2014a). Based on this classification, manufacture, 

servicing, and use of R-450A is not expected to present a flammability risk in the chillers and industrial 

process air-conditioning end-uses.

7. OCCUPATIONAL EXPOSURE ASSESSMENT

To ensure that use of the proposed substitute in chillers and industrial process air-conditioning does not 

pose an unacceptable risk to workers during installation, servicing, and disposal, occupational exposure 

modeling at installation was performed for the proposed substitute. Although modeling is only performed 

for installation, it is assumed that exposure during servicing and disposal would not exceed exposure 

during installation because similar refrigerant charging and/or recovery equipment would be used. All 

installation, maintenance, and disposal activities for R-450A chillers and industrial process airconditioning systems are anticipated to occur on-site. 

The submitter anticipates that R-450A chillers will have typical a charge size of 700 kg up to 2,000 kg for 

centrifugal chillers and 80 kg to 100 kg for industrial reciprocating, and screw chillers. Industrial process 

air-conditioning system charge sizes can vary greatly by construction (i.e., self-contained or built in situ). 

A 40-ton built in situ system would have a charge size ranging from 85 to 95 kg of R-450A (Honeywell 

2014b). The anticipated maximum and typical charge sizes for the proposed applications are summarized

in Table 5. 

Table 5. Typical and Maximum Charge Sizes for R-450A Chillers and Industrial Process AirConditioning Applications

End-Use Application Typical Charge 

Size (kg)

Maximum Charge 

Size (kg)

Chillers

Centrifugal, commercial buildings 700 2,000

Industrial, reciprocating/screw compressors 

(varies by load, application, and refrigerant feed) 80 100

Industrial Process 

Air-Conditioning*

Built in situ system 85 95

*Varies greatly by construction. Systems can be self-contained or built in situ.

Servicing of R-450A chillers and industrial process air-conditioning systems is assumed to not exceed 

exposures during installation and disposal. Installation and disposal are anticipated to have similar 

exposures, since both require the use of similar refrigerant charging and/or recovery equipment as well as 

the connection of pipes to transfer the refrigerant; because it is likely that less refrigerant remains in the 

unit at disposal, it is assumed that installation of a chiller or industrial process air-conditioning system 

would require transfer of a greater amount of refrigerant, and thus result in greater worker exposure. Thus, 

occupational exposure was conservatively modeled based on installation.

Installation of chillers and industrial process air-conditioning systems is expected to occur with limited 

frequency (up to approximately one event per day) and with limited duration of exposure to the refrigerant 

charge. Release points during charging would be connection/disconnection of temporary lines from 

charging equipment. Refrigerant contained in temporary lines during charging would be recovered, and 

breaking of fittings should result in de minimus releases (Honeywell 2014a). Such activities and related 

exposure is anticipated to occur within 15-30 minutes (per event/day). To evaluate the risk of exposure at 
Final -- October 10, 2014

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installation, the maximum modeled exposure concentration was compared to 2,640 ppm, the R-450A 

STEL developed by EPA based on R-450A’s 880 ppm AEL value.

The methodology used for this screening assessment is described in Chapter 5 of the Background 

Document. A box-model approach was used to evaluate potential worker exposure to alternative 

refrigerants. This approach has been widely used for many years to estimate probable exposures of 

workers to hazardous airborne materials, and has been described in detail by the National Institute for 

Occupational Safety and Health (NIOSH). This model takes into consideration the duration and magnitude 

of the resulting exposure which is influenced by 1) duration and intensity of the release, 2) rate at which 

contaminated air is diluted with uncontaminated air, 3) proximity of the worker to the source of the 

release, and 4) the length of time the worker remains in the affected space. 

The release per event was assumed to be 0.2 percent of the equipment charge during installation5and was 

multiplied by the number installations estimated to occur over a workday. The analysis models the 

maximum anticipated charge sizes for chillers and industrial process air-conditioning, as provided by the 

submitter (i.e., 2,000 kg and 95 kg, respectively). The maximum 15-minute time weighted average (TWA) 

exposures for R-450A was estimated for the installation scenario and compared to the short-term exposure 

limit for R-450a (see Table 6).

Table 6. Occupational Risk Assessment at Charging and Servicing for R-450Aa

Equipment Charge Size 

(kg)

15-minute TWA Occupational 

Exposure (ppm)

15-min Short Term 

Exposure Limits 

0.2% Release (ppm)

Centrifugal Chiller 2,000 530

2,640b Built in situ Industrial Process AirConditioner 95 100

Bold font indicates modeling results.

a Cells highlighted in green are the scenarios that are deemed to be acceptable given various modeling assumption options.

b EPA-derived STEL (see Table 3)

Based on the assumptions described above, the modeling indicates that short-term (15-minute) worker 

exposure concentrations are not likely to exceed the STEL (2,640 ppm) for R-450A for the maximum 

charge size for either equipment type. In addition, these types of systems are typically installed, 

maintained, and disposed by trained and EPA Section 608-certified refrigerant technicians using proper 

industrial hygiene techniques. When installing, servicing, or disposing of large chillers, these techniques 

should be strictly followed. Adherence to the proposed substitute’s MSDS and use of proper engineering 

controls and PPE make it unlikely that exposure to R-450A would occur. Adequate ventilation should 

always be established during any use, handling, or storage of R-450A. Engineering controls should include 

vapor-in air detection systems and local exhaust ventilation during use of R-450A to prevent dispersion 

throughout the workplace. In addition, an eye wash and safety shower should be near the manufacturing 

facility and locations where R-450A is stored and ready for use. In general, use of PPE is recommended, 

such as splash goggles, mechanically-resistance gloves when handling cylinders and chemically-resistant 

gloves when handling the gas mixture (e.g., butyl rubber, chlorinated polyethylene, or neoprene). EPA 

believes that if proper handling and disposal guidelines are followed in accordance with good industrial 

hygiene and manufacturing practices and the MSDS for R-450A, there is no significant risk to workers 

during the manufacturing, installation, servicing, and disposal of R-450A in chillers and industrial process 

air-conditioning. 

 

5

IPCC (2006) estimates that first-fill losses during installation of chillers can range from 0.2% to 1% and DECC (2011) estimates 

first-fill losses for chillers is approximately 0.5%; however, industry representatives indicate that the first-fill leak rate for chillers 

is lower than 0.5% (McQuay 2011). A proposed update to EPA’s Vintaging Model recommends a first-fill emissions rate of 0.2% 

from chillers manufactured after 1990.
Final -- October 10, 2014

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In addition, as for other halogenated refrigerants, there is a risk of generation of toxic degradation products 

such as hydrogen fluoride and hydrogen chloride if the components of R-450A (i.e., HFC-134a or HFO1234ze(E)) are exposed to high temperatures or fire. Other reaction products such as carbon dioxide might 

also be present. Containers should be stored in cool, dry conditions (maximum storage temperature should 

be 40C) in well-sealed receptacles and should not be allowed to contact open flames, glowing metal 

surfaces, or electrical heating elements. EPA believes that when proper handling and disposal guidelines 

are followed in accordance with both good industrial hygiene practices and the MSDS for R-450A and its 

components, there is no significant risk to workers during the use of R-450A.

8. GENERAL POPULATION EXPOSURE ASSESSMENT

R-450A is not expected to cause a significant risk to human health in the general population when

manufactured for use and used as a refrigerant in chillers and industrial process air-conditioning systems. 

The proposed substitute will be manufactured in a closed process and is proposed for use in closed 

systems; thus, significant releases are not anticipated. At room temperature, R-450A is a gas and, 

therefore, releases to ground or surface water are not anticipated, as R-450A is anticipated to dissipate into 

the atmosphere upon release to outside air (i.e., because natural ventilation rates would be higher and there 

is no enclosed space to maintain a high concentration of R-450A). Should air releases during 

manufacturing operations occur, engineering controls should be used (e.g., carbon absorption scrubbers) to 

collect R-450A and prevent the release of R-450A to the atmosphere. EPA believes that by using proper 

engineering controls and by following disposal and containment recommendations outlined in the 

proposed substitute’s MSDS, exposure to R-450A is not expected to pose a significant toxicity risk to the 

general population. 
Final -- October 10, 2014

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9. REFERENCES

ACGIH. 2012. Guide to Occupational Exposure Values. American Conference of Governmental 

Industrial Hygienists.

ANSI/ASHRAE. 2010a. Standard 15: Safety Standard for Refrigeration Systems. American Society of 

Heating, Refrigerating and Air-Conditioning Engineers, Inc.

ANSI/ASHRAE. 2010b. Standard 34: Designation and Safety Classification of Refrigerants. American 

Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. 

ANSI/ASHRAE. 2013a. Standard 62: Ventilation for Acceptable Indoor Air Quality. American Society 

of Heating, Refrigerating and Air-Conditioning Engineers, Inc.

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. Changes in 

Atmospheric Constituents and in Radiative Forcing. In: Climate Change 2007:The Physical Science 

Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel 

on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and 

H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

Hodnebrog, Ø., Etminan, M., Fuglestvedt, J. S., Marston, G., Myhre, G., Nielsen, C. J., Shine, K. P., 

Wallington, T. J. 2013. Global Warming Potentials and Radiative Efficiencies of Halocarbons and 

Related Compounds: A Comprehensive Review, Reviews of Geophysics, 51, 300-378, 

doi:10.1002/rog.20013.

Honeywell, Inc. 2014a. Solstice® N-13 (R-450A). Significant New Alternatives Policy Program 

Submission to the United States Environmental Protection Agency. May 2014.

Honeywell, Inc. 2014b. Response to Incompleteness Letter for Solstice® N-13 (R-450A) Significant New 

Alternatives Policy Program Submission to the United States Environmental Protection Agency. August 

11, 2014.

ICF. 1997. Physiological Effects of Alternative Fire Protection Agents - Hypoxic Atmospheres 

Conference. Stephanie Skaggs prepared the proceedings of the conference held May 22, 1997 in New 

London, CT.

IPCC. 2006 IPCC Guidelines for National Greenhouse Gas Inventories. Volume 3: Industrial Processes 

and Product Use, Chapter 7: Emissions of Fluorinated Substitutes for Ozone Depleting Substances.” 

November 2008. Available at: http://www.ipccnggip.iges.or.jp/public/2006gl/pdf/3_Volume3/V3_7_Ch7_ODS_Substitutes.pdf. 

McQuay International (2011). Personal communication between Jim Henley (McQuay International) and 

Pamela Mathis (ICF International). 14 November 2011.

OSHA. 2004. “Safety and Health Topics: Isobutane.” February 2004. Available online at: 

<http://www.osha.gov/dts/chemicalsampling/data/CH_247840.html>.

UK Department of Energy & Climate Change (DECC). 2011. “Development of the GHG Refrigeration 

and Air Conditioning Model.” Prepared by ICF International. November 2011. Available at 

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/48250/3844-greenhousegas-inventory-improvement-project-deve.PDF.
Final -- October 10, 2014

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U.S. EPA 1994. Significant New Alternatives Policy Technical Background Document: Risk Screen on 

the Use of Substitutes for Class I Ozone-depleting Substances: Refrigeration and Air Conditioning. 

Stratospheric Protection Division. March, 1994.

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

http://www.epa.gov/oppt/aegl/pubs/define.htm.

WMO (World Meteorological Organization), 2011. Scientific Assessment of Ozone Depletion: 2010, 

Global Ozone Research and Monitoring Project-Report No. 52, 516 pp., Geneva, Switzerland.