Final -- October 10, 2014

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Significant New Alternatives Policy Program 

Refrigeration and Air Conditioning Sector

Risk Screen on Substitutes in Retail Food Refrigeration, Vending Machines, and 

Commercial Ice Machines

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 retail refrigeration (specifically, convenience 

stores, direct racks, indirect racks, remote condensing units, and stand-alone display cases), vending 

machines, and commercial ice machines end-uses. 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
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Constituent Chemical Formula CAS Number Concentration

(Weight Percent)a
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Constituent Chemical Formula CAS Number Concentration

(Weight Percent)a

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: Discussion of End-Use Scenario Modeled 

 Section 6: Potential Health Effects 

 Section 7: Flammability Assessment

 Section 8: Asphyxiation Assessment 

 Section 9: End-Use Exposure Assessment

 Section 10: Occupational Exposure Assessment 

 Section 11: General Population Exposure Assessment

 Section 12: References

2. SUMMARY OF RESULTS

R-450A is recommended for SNAP approval for the retail food refrigeration, vending machine, and 

commercial ice machine end-uses. EPA's risk screen indicates that the use of the proposed substitute will 

be less harmful to the atmosphere than the continued use of CFC-12, R-502, and HCFC-22, as well as 

other commonly used refrigerants, 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 retail food refrigeration systems, vending 

machines, and commercial ice machines using R-450A. Because retail food refrigeration systems, vending

machines, and commercial ice machines are to be installed in locations with adequate space and/or 

ventilation in accordance with EPA recommendations and the equipment maintenance manuals for R-
Final -- October 10, 2014

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450A in each end-use, significant toxicity risk to consumers is also unlikely. In addition, because R-450A 

is considered to be nonflammable, the proposed substitute is not expected to present a flammability 

concern. 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 Air-Conditioning Engineers (ASHRAE) Standards 15,1 34,2and 62.3

3. ATMOSPHERIC ASSESSMENT

This section presents an assessment of the potential risks to atmospheric integrity posed by the use of R450A in retail food refrigeration, vending machines, and commercial ice machines. The ozone depletion 

potential (ODP), global warming potential (GWP), and atmospheric lifetime (ALT) of the proposed 

substitute are presented in 

 

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.
Final -- October 10, 2014

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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 CFC12, R-502, and HCFC-22. 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 refrigerants HFC-134a, R-404A, R-507A, and R-407C. Thus, EPA 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 other commonly used refrigerants. 
Final -- October 10, 2014

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

Refrigerant Ozone Depleting Potential

(ODP)a

Global Warming Potential

(GWP)b

Atmospheric Lifetime in 

Years (ALT) 

R-450A 0 601 NAc

Individual Components

HFC-134a 0 1,430 14b

HFO-1234ze(E) 0 1

d 16.4 daysd

CFC-12 0.82 10,900 100b

R-502e 0.2 4,650 NAf

HCFC-22 0.13 1,810 12a

HFC-134a 0 1,430 14b

R-404Ag 0 3,922 NAh

R-507Ai 0 3,985 NAj

R-407Ck 0 1,774 NAl

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 16.4 days (IPCC 4th Assessment Report [Forster et al. 2007], Hodnebrog, O. et al. [2013]).

d Hodnebrog, O. et al. (2013)

e R-502 is a blend consisting of HCFC-22 (49%) and CFC-115 (51%). 

f Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for HCFC-22 is 12 years and the 

ALT for CFC-115 is 1,700 years (IPCC 4th Assessment Report [Forster et al. 2007]).

g R-404A is a blend consisting of HFC-143a (52%), HFC-125 (44%) and HFC-134a (4%). 

h Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for HFC-143a is 52 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]).

i R-507A is a blend consisting of HFC-125 (50%) and HFC-143a (50%).

j Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for HFC-125 is 29 years and

ALT for HFC-143a is 52 years (IPCC 4th Assessment Report [Forster et al. 2007]).

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

l 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. DISCUSSION OF END-USE SCENARIOS MODELED

The submission states that R-450A retail food refrigeration equipment will have typical charge sizes 

ranging from 0.9 kg for a stand-alone, self-contained display case to 300 kg for a direct rack system. For 

vending machines, the submission states that R-450A will have a typical charge size of 0.5 kg. 

Commercial ice machines are anticipated to have a typical charge size of 10 kg and a maximum charge 

size of 50 kg. The intended maximum and typical charge sizes for all of the proposed applications are 

listed in Table 3. 
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Table 3. Typical and Maximum Charge Sizes for Various R-450A End-Uses and Applications

End-Use Application Typical Charge Size 

(kg)

Maximum Charge Size 

(kg)

Retail food 

refrigeration

Convenience Store 30 60

Direct rack / 4 compressor 300 400

Indirect rack / 4 compressor 150 250

Remote condensing unit / air-cooled 5 hp unit 10 12

Remote condensing unit / air-cooled 10 hp unit 36 47

Stand-alone self-contained display case 0.9 1.2

Vending machines Vending machines 0.5 2

Commercial ice 

machines Commercial ice machines 10 50

Bolded applications represent those modeled in this risk screen.

To represent a reasonable worst-case scenario for the retail food refrigeration end-use, it is assumed that a 

catastrophic leak of refrigerant occurs while a direct rack system and a stand-alone beverage cooler are 

installed at the end-use (i.e., a grocery supermarket and a convenience store, respectively). The analysis 

considers the typical charge size provided by the submitter for each scenario. Because retail refrigeration 

equipment can be installed in a wide range of locations with varying room volumes, the analysis in this 

risk screen conservatively assumes that the direct rack system is located in a grocery supermarket and the 

beverage cooler is located in a convenience store. The grocery supermarket is assumed to have an effective 

volume of 24,200 m3(855,000 ft3) with an effective floor area of 4,400 m2(i.e., excluding the space filled 

by the rack system, shelving, display cases, etc.) and a height of 5.5 meters (Armines 2008). The 

convenience store is assumed to have an effective volume of 244 m3(8,620 ft3) with an effective floor area 

of 102 m2(i.e., excluding the space filled by the beverage cooler, shelving, display cases, etc.) and a height 

of 2.4 meters. 

For the vending machine end-use, it is assumed that the vending machine is located in the minimum room 

size, an enclosed alcove of a commercial building that can be isolated by a door. The alcove is assumed to 

have an effective floor area of 6.15 m2(i.e., excluding the space filled by the vending machine, furniture, 

boxes, etc.) and a height of 2.4 meters, equivalent to a volume of 15 m3(530 ft3). 

For the commercial ice machines end-use, it is assumed that the ice machine is also located in a 

convenience store with an assumed effective volume of 244 m3(8,620 ft3), with an effective floor area of 

102 m2(i.e., excluding the space filled by the beverage cooler, shelving, display cases, etc.) and a height of 

2.4 meters).

Under these worst-case scenarios, the full charge of each unit is assumed to be emitted over the course of 

one minute, into the grocery supermarket, convenience store, or enclosed alcove with 8, 1, and 0.5 air 

changes per hour (ACH), respectively4 over the course of two time durations: 1) one minute, which 

represents a catastrophic release of refrigerant due to a puncture or other major damage to the refrigeration 

system, and 2) fifteen minutes, which represents the accidental release of refrigerant due to a noncatastrophic leak in the system (e.g., valve failure). The one-minute time duration is most appropriate for 

flammable refrigerants and presents a less relevant scenario for R-450A, which is nonflammable. 

Therefore, while both scenarios are evaluated in this risk screen for consistency purposes, the scenario 

which analyzes a release of refrigerant over a 15-minute time duration more accurately represents a 

reasonable worst-case scenario for R-450A in retail food refrigeration, vending machines, and commercial 

ice machines. 

 

4 The air exchange rate is derived from the requirements in ANSI/ASHRAE Standard 62.1-2007, Table 6.1 (ANSI/ASHRAE 

2007). Ventilation requirements (presented as cubic feet per minute per square foot of ventilated space in the standard) were 

converted to air exchanges per hour using the assumed room size for the scenario.
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A vertical concentration gradient is also assumed since R-450A is denser than air (the specific gravities of 

both HFC-134a and HFO-1234ze(E) are greater than 1) and will settle in higher concentrations closer to 

the ground. In order to simulate the vertical concentration gradient, it is assumed that 95 percent of the 

leaked refrigerant mixes evenly into the bottom 0.4 meter of the room, and the rest of the refrigerant mixes 

evenly in the remaining volume (Kataoka 2000). Table 4 details the end-use modeling assumptions used 

throughout the risk screen (i.e., in Sections 8, 9 and 10).

Table 4. End-Use Scenario Model Assumptions 

Parameter Assumptions 

(Large Retail 

Food)

Assumptions (Small 

Retail Food)

Assumptions 

(Vending Machine)

Assumptions (Ice 

Machine)

Refrigeration Unit Direct Rack 

System

Stand-Alone Beverage 

Cooler Vending Machine Ice Machine

Room Grocery 

Supermarket Convenience Store Enclosed Alcove Kitchen of Small Fast Food Restaurant

Charge Size (kg) 300; 400 0.9; 1.2 0.5; 2 10; 50

Length of Release 

(minutes) 1; 15 1; 15 1; 15 1; 15

Room Size (volume - m3) 24,200a 244b 15 244b

Room Ventilation (air

changes per hour) 8 1 0.5 1

Vertical Concentration 

Gradient Yes Yes Yes Yes

a The average grocery supermarket sales area size found during a California survey (Armines 2008) – 4,400 m2 – was used for this scenario and 

a 5.5 m (18-foot) ceiling was assumed.

b Specific information was not available regarding which types of stores would utilize beverage cases or commercial ice machines, so a small 

store (i.e., a convenience store) was used in the model. The minimum convenience store size found during a California survey (Armines 2008) –

100 m2 – was used for this scenario and an 8-foot ceiling was assumed.

EPA recognizes that direct rack systems, beverage coolers, other retail food refrigeration units, vending 

machines, and commercial ice machines may be placed in a variety of stores, establishments, and rooms 

with different sizes and ventilation rates. When units are installed in smaller, enclosed spaces, there is a 

higher risk for asphyxiation or exposure concerns. To address this variability in room volumes and charge 

sizes for installed retail food equipment, vending machines, and commercial ice machines, this risk screen 

incorporates threshold analyses in addition to the worst-case scenario modeling. The threshold analyses are 

performed in order to determine the room size and charge size requirements that ensure that the use of R450A in retail food refrigeration, vending machines, and commercial ice machines does not present risk to 

end-users or servicing technicians.

6. POTENTIAL HEALTH EFFECTS

To assess potential health risks from exposure to the proposed substitute in retail food refrigeration, 

vending machines, and commercial ice machines, 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 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 
Final -- October 10, 2014

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

flammability, asphyxiation, and end-use exposure risks, respectively, 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 (WGLs). Risks from potential 

short-term consumer exposures were evaluated by comparing exposure concentrations to emergency 

guidance levels (EGLs). 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 5 lists the relevant toxicity limits for R-450A and its components and is followed by Table 6, 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 5. 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) 8,000 (10-min AEGL-1)

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

HFO-1234ze(E) 800 (8-hour WEEL) 2,400 (15-min STEL)b NAc

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 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

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

Table 6. 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 
Final -- October 10, 2014

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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.

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. 
Final -- October 10, 2014

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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 

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.

7. 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 2014). Based on this classification, manufacture, 

servicing, and use of R-450A is not expected to present a flammability risk in the retail food refrigeration, 

vending machines, or commercial ice machine end-uses.

8. ASPHYXIATION ASSESSMENT

The risk of asphyxiation for the reasonable worst-case scenario was investigated for R-450A. In this 

section, risk of asphyxiation is assessed in three ways: 1) modeling the oxygen concentration under the 

charge size and room size specified in the worst-case scenario, 2) performing a threshold analysis of 

minimum charge size needed to cause an asphyxiation risk in the room size specified in the worst-case 

scenario 3) performing a threshold analysis of the maximum room size needed to cause an asphyxiation 

risk with the charge size specified in the worst-case scenario. This analysis does not consider ventilation 

or conditions that are likely to occur that would increase oxygen levels to which individuals would be 

exposed, such as open doors or windows, fans operating, conditioned airflow (either heated or cooled), or 

even openings at the bottom of doors that allow air to flow in and out. As specified in Section 5, the 

reasonable worst-case scenario assumes a vertical concentration gradient. If the proposed substitute passes

the screening analysis with these restrictive assumptions in place, it can be reasonably assumed that no 

risks of asphyxiation will be present under real-world conditions. The results of the asphyxiation 

assessment are summarized in Table 7 below. 

Table 7. Asphyxiation Assessmenta,b

Equipment Scenario Charge Size 

(kg)

Effective Room Size 

(m3)

Percent Oxygen 

Concentration in 

Lower 0.4 Meters

Direct Rack 

System Reasonable Worst-Case 1 300 24,200 (855,000 ft3

) 20%

Beverage 

Cooler Reasonable Worst-Case 2 0.9 244 (8,620 ft3

) 21%

Vending 

Machine Reasonable Worst-Case 3 0.5 15 (530 ft3

) 20%

Ice Machine Reasonable Worst-Case 4 10 50 (1,770 ft3) 20%

Direct Rack 

System

Threshold Analysis 1a: Charge Size 1,360 24,200 (855,000 ft3) 12%

Threshold Analysis 1b: Room Size 300 5,330 (18,800 ft3) 12%

Beverage 

Cooler

Threshold Analysis 2a: Charge Size 30.9 244 (8,620 ft3) 12%

Threshold Analysis 2b: Room Size 0.9 7 (250 ft3) 12%

Vending 

Machine

Threshold Analysis 3a: Charge Size 1.9 15 (530 ft3) 12%

Threshold Analysis 3b: Room Size 0.5 4 (140 ft3) 12%

Ice Machine Threshold Analysis 4a: Charge Size 31 50 (1770 ft3

) 12%

Threshold Analysis 4b: Room Size 10 79 (2,790 ft3) 12%

Bold font indicates modeling results.

a Cells highlighted in green are the scenarios in which the charge and room sizes evaluated in this risk screen are acceptable according to the 

threshold analysis or the scenarios with acceptable oxygen concentrations, given various modeling assumption options.

b The typical concentration of oxygen in air is considered to be 21 percent (Mackenzie & Mackenzie 1995).
Final -- October 10, 2014

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Based on the worst-case scenario modeling assumptions, R-450A in retail food refrigeration, vending 

machines, and commercial ice machines does not present a significant risk of asphyxiation. In order for a 

risk of asphyxiation to occur, the normal concentration of oxygen in air (21 percent) in the lower 0.4 

meters of the room must be reduced to 12 percent.5 Based on the reasonable worst-case scenario modeling 

assumptions, use of R-450A in retail food refrigeration equipment, vending machines, and commercial ice 

machines does not present a significant risk of asphyxiation:

 As shown in Threshold Analysis 1a for direct rack systems, the minimum charge size of R-450A 

necessary to reduce the oxygen levels to 12 percent in air in the lower 0.4 meters of a room of 

volume 24,200 m3(855,000 ft3) was calculated to be 1,360 kg assuming that 1) nitrogen and 

oxygen retain the same relative volumes in the rooms with the balance composed entirely of R450A, and 2) the pressure of the room does not increase significantly with the addition of the 

refrigerant. This amount represents almost five times the typical charge of approximately 300 kg 

(or more than three times the maximum charge size of 400 kg) for a direct rack R-450A system. 

 Under Threshold Analysis 2a for beverage coolers, the minimum charge of R-450A necessary to 

reduce the oxygen levels to 12 percent in air in the lower 0.4 meters of a room of volume 244 m3

(8,620 ft3) was calculated to be 30.9 kg, which represents almost 35 times the typical charge of 0.9 

kg for a single R-450A beverage cooler (or 25 times the maximum intended charge size of 1.2 kg). 

 For vending machines, Threshold Analysis 3a shows that under similar assumptions, the minimum 

charge of R-450A necessary to reduce oxygen levels to 12% in air in the lower 0.4 meters of a 

room of volume 15m3(530 ft3) was calculated to be 1.9 kg, almost four times the typical charge of 

approximately 0.5 kg for a vending machine. The maximum charge size intended for R-450A 

vending machines of 2 kg, does exceed the maximum charge size for which an asphyxiation risk 

could occur in the specified area (i.e., 15 m3) under the assumptions specified in Section 5. 

 For commercial ice machines, Threshold Analysis 4a shows that the minimum charge of R-450A 

necessary to reduce oxygen levels to 12% in air in the lower 0.4 meters of a room of volume 244 

m3(8,620 ft3) was calculated to be 31 kg, more than three times the typical charge of 

approximately 10 kg for a commercial ice machine. The maximum charge size intended for R450A commercial ice machine of 50 kg, does exceed the maximum charge size for which an 

asphyxiation risk could occur in the specified area (i.e., 244 m3) under the assumptions specified in 

Section 5. 

Because this threshold modeling does not take into account any ventilation which is likely to occur, such 

as conditioned airflow, open doors, or even openings at the bottom of doors that allow air to flow in and 

out, as mentioned above, the actual asphyxiation risk to consumers is likely to be smaller than modeled. 

For the room size Threshold Scenarios, the room size at which an asphyxiation concern would exist (i.e., 

when the oxygen concentration in the lower 0.4 meters of the room is 12 percent) using the typical 

equipment charge sizes provided by the submitter were also determined: 

 For direct rack systems, in order for asphyxiation to be of concern with a charge size of 300 kg, 

the system would have to be installed in a store with an effective volume of 5,330 m3(18,800 ft3) 

(see Threshold Analysis 1b in Table 7).

 For beverage coolers, in order for asphyxiation to be of concern with the typical charge size of 0.9 

kg, the volume of the food preparation area would have to be about 7 m3(250 ft3) (see Threshold 

Analysis 2b in Table 7). 

 For vending machines, Threshold Analysis 3b indicates that the volume of the vending machine 

area would have to be about 4 m3(140 ft3) with the typical charge size of 0.5 kg in order for 

asphyxiation to be a concern. 

 

7 Twelve percent oxygen in air is the No Observed Adverse Effect Level (NOAEL) for hypoxia (ICF 1997).
Final -- October 10, 2014

13

 For commercial ice machines, Threshold Analysis 4b indicates that the volume of the commercial 

ice machine area would have to be about 79 m3(2,790 ft3) with the typical charge size of 10 kg in 

order for asphyxiation to be a concern. 

Based on the worst-case modeling results and threshold analysis, EPA does not believe that the use of R450A in retail food refrigeration, vending machines, and commercial ice machines poses a significant risk 

of asphyxiation or impaired coordination to personnel, provided systems are installed in appropriate spaces 

according to guidelines from the manufacturer and the MSDS for R-450A.

9. END-USE EXPOSURE ASSESSMENT

This section presents estimates of potential end-user exposures to R-450A and each of its chemical 

constituents in the event of a catastrophic release from the proposed substitute’s use in retail food 

refrigeration, vending machines, and commercial ice machines. An end-use exposure analysis was 

performed to examine potential catastrophic releases of R-450A under the reasonable worst-case scenarios 

outlined in Section 5.

For the end-use exposure assessment scenario, 15-minute TWA exposures for the proposed substitute were 

calculated using the box model described in the Background Document, which was adapted to estimate 

concentrations on a minute-by-minute basis. Estimates for acute/short-term end-use exposures resulting 

from catastrophic leakage of refrigerant from retail food refrigeration, vending machines, and commercial 

ice machines were examined. The analysis was undertaken to determine the 15-minute exposures for R450A, which were then compared to the standard toxicity limits presented in Table 5 to assess the risk to 

end-users. Because HFO-1234ze(E) is present in larger concentrations and because it has a lower exposure 

limit than HFC-134a, Table 8 displays only HFO-1234ze(E), the component with greater potential 

concerns. The estimated TWA values are fairly conservative as the analysis does not consider opened 

windows, fans operating, conditioned airflow (either heated or cooled) and other variables that would 

reduce the levels to which individuals would be exposed. 

Table 8. End-Use Exposure Assessment for HFO-1234ze(E) Componenta,b

Equipment Scenario Charge 

Size (kg)

Room 

Size (m3)

Length of 

Release (min)

15-min TWA End-Use 

Exposure (ppm)

Direct Rack 

System

Reasonable Worst-Case Scenario 1a 300 24,400 1 18,600

Reasonable Worst-Case Scenario 1b 15 10,100

Beverage 

Cooler

Reasonable Worst-Case Scenario 2a 0.9 244

1 2,460

Reasonable Worst-Case Scenario 2b 15 1,340

Vending 

Machine

Reasonable Worst-Case Scenario 3a

0.5 15

1 22,200

Reasonable Worst-Case Scenario 3b 15 12,100

Ice Machine

Reasonable Worst-Case Scenario 4a

10 244

1 27,400

Reasonable Worst-Case Scenario 4b 15 14,900

Bold font indicates modeling results.

a Cells highlighted in green are the scenarios with acceptable exposure levels given various modeling assumption options.

b 15-min STEL for HFO-1234ze(E) is 2,400 ppm and ATEL for HFO-1234ze(E) is 59,000 ppm; see Table 4 for more information.

Under the reasonable worst-case scenarios described in Section 5 for direct rack systems, beverage coolers, 

vending machines, and ice machines catastrophic releases of the typical charge sizes of R-450A were 

modeled. The modeling scenarios evaluate two refrigerant release time durations (i.e., 1 minute and 15 

minutes). The anticipated 15-minute TWA exposures for the HFO-1234ze(E) component of R-450A are 

likely to exceed its STEL (i.e., 2,400 ppm) for all scenarios except Reasonable Worst-Case Scenario 2b, 

which assumes a 15-minute release for a beverage cooler in a convenience store. Although most of the 

exposure estimates for the reasonable worst-case scenarios exceed the STEL (i.e., 2,400 ppm) (see Table 
Final -- October 10, 2014

14

8), the STEL is a conservatively-derived exposure limit that is intended to protect against risk with a wide 

safety margin for even the most sensitive of populations. All of these exposure estimates are significantly 

lower than the acute toxicity exposure limit (ATEL) of 59,000 ppm for HFO-1234ze(E), which is a 

refrigerant concentration limit intended to reduce the risks of acute toxicity hazards in normally occupied, 

enclosed spaces according to ASHRAE Standard 34. Furthermore, the estimated exposures for R-450A in 

each of these scenarios are also significantly lower than the RCL for R-450A (i.e., 72,000 ppm). 

In addition, these exposure estimates were derived using fairly conservative assumptions (e.g., minimum 

room volume, low ventilation rate, maximum charge size) that do not necessarily reflect the actual room 

attributes where R-450A retail food refrigeration equipment, vending machines, and commercial ice 

machines will be installed. Finally, these exposures represent concentrations of leaked refrigerant in the 

bottom 0.4 meter (1.3 feet) of the room, accounting for 95 percent of the refrigerant charge in this lower 

compartment of the room. The probability that an individual would be present in this lower compartment 

(e.g., prone or supine on the floor) in the event of the catastrophic release of refrigerant is low.

To prevent exposure and potential serious side effects during larger releases, EPA recommends that the 

proposed RCL for R-450A (i.e., 72,000 ppm or 320 g/m3) is not exceeded in any location where an R450A system is installed, unless proper leak protection devices are in place in order to prevent exposures 

of R-450A beyond the recommended limits. Proper leak protection devices, engineering control 

requirements, and adherence to the MSDS will further ensure that exposure limits are maintained below

those described in Table 8. 

10. OCCUPATIONAL EXPOSURE ASSESSMENT

This section assesses potential exposures to workers during manufacture, charging and servicing, and 

disposal of R-450A retail food refrigeration equipment, vending machines, and commercial ice machines. 

To ensure that use of the proposed substitute in retail food refrigeration, vending machines, and 

commercial ice machines does not pose an unacceptable risk to workers during servicing and disposal, 

occupational exposure modeling was performed using a box-model approach. For a detailed description of 

the methodology used for this screening assessment, the reader is referred to the occupational exposure and 

hazard analysis described in Chapter 5 of the Background Document. 

Estimates of refrigerant release per event for various release scenarios were obtained from the Vintaging 

Model.6 To determine the estimated level of occupational exposure for a constituent in a blend, the total 

anticipated release rate of the refrigerant is multiplied by the weight percent composition of each 

compound in the blend; however, only the exposure concentrations for the HFO-1234ze(E) component are 

shown. For the retail food refrigeration and vending machine end-uses, the release per event was 

conservatively assumed to range between 0.25 percent and 5 percent of the equipment charge during 

charging and servicing (see Section 10.2) and 13.5 to 81 percent of the equipment charge during disposal 

(see Section 10.3). The release rate per event was multiplied by the number of events estimated to occur 

over a workday. For equipment charging and servicing, the number of events per workday was assumed to 

equal the maximum number of units anticipated to be serviced in one day (i.e., eight units divided by eight 

hours per workday for beverage coolers, vending machines, and commercial ice machines, and one unit 

divided by eight hours per workday for direct rack systems). For disposal, it was conservatively assumed 

that 10 units are disposed during an 8-hour work day for smaller equipment and one unit per day for direct 

rack systems. The modeled exposure concentrations were compared to short-term occupational exposure 

limits at installation and servicing and long-term exposure limits at disposal.

 

6

ICF International maintains the Vintaging Model for EPA in order to simulate the aggregate impacts of the ODS phaseout on the

use and emissions of various ODS and their substitutes over a period of several years across 60 different end-uses. The model 

tracks the use and emissions of various compounds for the annual vintages of new equipment that enter service in each end-use. 

The vintage of each type of equipment determines such factors as leak rate, charge size, number of units in operation, and the 

initial ODS substance that the equipment contained. 
Final -- October 10, 2014

15

10.1 Occupational Exposure at Manufacture

HFC-134a is obtained by the submitter from other manufacturers and HFO-1234ze(E) is manufactured by 

the submitter in the United States. During manufacture of the components and blending of R-450A, the 

MSDS for both HFC-134a and HFO-1234ze(E) should be referenced and proper engineering controls and 

PPE used. 

R-450A and its components are not expected to pose a risk to workers during manufacture or blending 

when the engineering controls and PPE recommendations referenced in the MSDS for HFC-134a, HFO1234ze(E), and R-450A are followed. Release points/exposure in chemical manufacturing would typically 

be where temporary lines are connected or disconnected (i.e., filling of portable cylinders and portable 

bulk containers). Refrigerant quality control testing may result in release of de minimus quantities of 

refrigerant, which would typically be to exhaust ducts or fume hoods. Engineering controls should include 

normal and local ventilation (e.g., chemical hoods) and vapor-in-air detection and alarm systems for 

standard manufacturing procedures so workers can avoid physical contact with the refrigerant and to 

achieve emission control. In general, use of PPE consistent with OSHA guidelines is recommended, such 

as respiratory protection (including a SCBA in case of insufficient ventilation), tightly sealed goggles, and 

protective gloves (OSHA 1994).

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 HFC-134a or HFO-1234ze(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 and manufacturing practices and the MSDS for R-450A and its components, 

there is no significant risk to workers during the manufacture of R-450A.

10.2 Occupational Exposure at Charging and Servicing

As indicated by the submitter, large commercial refrigeration equipment (e.g., direct rack systems) is 

typically field-erected and therefore equipment is charged in the field. Smaller retail refrigeration 

equipment (e.g, beverage coolers), vending machines, and commercial ice machines would occur by the 

Original Equipment Manufacturer (OEM). For both OEM system manufacture (i.e., charging at OEM 

location) and field charging (i.e., charging at the end-use location), points of release for charging and 

servicing these leak-tight systems would be from connection/disconnection of temporary lines for charging 

and recovery equipment.

Charging occurs within an enclosed area equipped with automatic ventilation, refrigerant detectors, and 

alarm systems. The submitter indicated that charging equipment is operated only by trained technicians. 

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 2014).

During servicing, used refrigerant from R-450A retail food refrigeration equipment, vending machines, 

and commercial ice machines is pumped into a canister, where it is stored until it is recycled (i.e., filtered 

and reused). During the transfer to the initial canister, incidental refrigerant releases may occur during 

connection and disconnection of the recharging hose fittings (Honeywell 2014). Isolation and evacuation 

of lines or equipment prior to servicing or repair and the use of compatible seals, gaskets, O-rings, thread 

sealants, and minimization of threaded joints all contribute to limiting releases. Room ventilation, leak 

monitors, and alarms also help minimize exposure. 
Final -- October 10, 2014

16

Charging and servicing activities for retail refrigeration equipment, vending machines, and commercial ice 

machines are not expected to result in significant worker exposure when certified technicians follow the 

procedures outlined in the R-450A MSDS and maintenance manual, undergo proper training, and wear 

appropriate PPE (e.g., gloves and safety glasses). Nevertheless, the potential occupational exposure during 

servicing was analyzed. The maximum 15-minute time weighted average (TWA) exposures for each R450A constituent were estimated for the servicing exposure scenario and compared to their respective 

short-term exposure limits (see Table 9). Because HFO-1234ze(E) is present in larger concentrations and 

because it has a lower exposure limit than HFC-134a, Table 9 displays results only for HFO-1234ze(E), 

the component with greater potential concerns.

Table 9. Occupational Risk Assessment at Charging and Servicing for HFO-1234ze(E) Componenta

Equipment

Charging Servicing 15-min Short 

Term Exposure 

Limits (ppm) Release Rateb

15-minute 

TWA (ppm) Release Rateb

15-minute 

TWA (ppm)

Direct Rack Systemc 2% 440 5% 1,100

2,400d

Beverage Cooler 1% 5 0.25% 1.3

Vending Machine 1% 3 0.25% 0.74

Ice Machine 1% 59 3% 180

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 Release rates are consistent with IPCC (2006) and CARB (2013)

c One installation or servicing event per day was modeled for direct rack systems

d EPA-derived STEL (see Table 4)

The 15-min STEL for HFO-1234ze(E) is not exceeded in the charging or servicing exposure scenarios for 

all four equipment types. In addition, the estimated exposures were derived using conservative 

assumptions, and do not take into account the use of ventilation or PPE. These types of systems are 

typically serviced by Section 608-certified personnel using proper industrial hygiene techniques and using 

proper engineering controls (e.g., local ventilation, refrigerant detectors, and alarm systems). Thus, EPA 

does not believe that charging, installation, or servicing of retail food refrigeration units, vending 

machines, and commercial ice machines containing R-450A presents a significant concern to workers.

10.3 Occupational Exposure at Disposal

Disposal of R-450A retail food refrigeration equipment is expected to occur with limited frequency (up to 

approximately ten disposal events per day for smaller equipment such as beverage coolers, vending 

machines, and commercial ice machines and one disposal event per day for direct rack systems) at disposal 

facilities or, for larger equipment (e.g., direct rack systems) at the end-use and with limited duration of 

exposure to the installed refrigerant. Typically, potential exposures to the refrigerant during recovery and 

disposal are expected to occur during activities related to decommissioning refrigeration systems (e.g., 

attaching of hoses associated with draining or otherwise discharging of refrigerant from the refrigeration 

units into cylinders) and would be similar to those during servicing, because similar refrigerant charging 

and/or recovery equipment would be used (see Section 10.2 and Table 9 for information and modeling 

results related to exposure during servicing activities). 

As shown in Table 9 in Section 10.2, exposures during servicing (and therefore during typical disposal 

activities) are not anticipated to present a significant concern for workers. To model a worst-case scenario 

during disposal, scenarios were modeled in which the portion of refrigerant that is not recovered during 

decommissioning of equipment (e.g., due to technical efficiency of recovery equipment) is released during 

the recovery process in the presence of workers. The implied maximum release rates workers could be 

exposed to under the reasonable worst-case disposal scenario are shown in Table 10.
Final -- October 10, 2014

17

Table 10. Assumed Release Rates during Disposal

Equipment Percent Remaining 

at Disposal

Recovery 

Efficiency

Implied Maximum 

Disposal Release Rate

Direct Rack System 90% 85% 14%

Beverage Cooler 90% 10% 81%

Vending Machine 90% 10% 81%

Ice Machine 80% 70% 24%

Source: Release rate assumptions consistent with IPCC (2006), UK DECC (2011) and CARB (2013)

Because HFO-1234ze(E) is present in larger concentrations and because it has a lower exposure limit than 

HFC-134a, Table 11 displays the maximum estimated 8-hour TWA occupational exposure levels for only 

HFO-1234ze(E) disposal, , the component with greater potential concerns. Based on the assumptions 

described in the beginning of Section 10, the modeling indicates the following:

 The 8-hour worker exposure concentrations for the HFO-1234ze(E) component will at no point 

exceed the long-term exposure limit (i.e., 800 ppm) during disposal of R-450A for beverage 

coolers and vending machines during the 81 percent release scenarios.

 Under the disposal release scenarios for the direct rack system and commercial ice machines, the 

modeling indicates that occupational exposure could exceed the 8-hour long term exposure limit 

for HFO-1234ze(E). 

Table 11. Occupational Risk Assessment at Disposal for HFO-1234ze(E) Componenta

Equipment Percent Release 8-Hour TWA Occupational 

Exposure (ppm)

8-Hour Long Term 

Exposure Limits (ppm)

Direct Rack System 14% 3,200

800b

Beverage Cooler 81% 570

Vending Machine 81% 320

Ice Machine 24% 1,900

Bold font indicates modeling results.

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

b WEEL OEL

Although the modeling indicates that the worse-case disposal scenario for direct rack systems and 

commercial ice machines could exceed the WEEL for HFO-1234ze(E), the estimated exposures were 

derived using conservative assumptions (e.g., no mechanical or local exhaust ventilation), and represent a 

worst-case scenario with a low probability of occurrence (e.g., for smaller commercial refrigeration 

equipment, it is highly unlikely that a worker would be exposed to the maximum release rate at disposal 

for every unit decommissioned in a day). These types of systems are also typically disposed of by Section 

608-certified personnel using proper industrial hygiene techniques to maximize recovery efficiency and 

limit releases. The average recovery efficiencies and maximum disposal release rates (see Table 10) are 

also representative of release rates for currently used refrigerants in commercial refrigeration equipment 

(e.g., HFC-134a, R-404A), and there are already established standards of practice and training 

requirements that apply to fluorinated refrigerants to reduce exposures (and would therefore extend to R450A systems). 

It is also unlikely that workers would be exposed to the unrecoverable portion of refrigerant during the 

recovery process, and therefore anticipated exposures would be much lower. For example, some of the 

refrigerant would likely be dissolved in the refrigerant oil (which would be drawn out and separated from 

the recovered refrigerant) or trapped within deeper parts of the refrigeration circuit (e.g., the accumulator 
Final -- October 10, 2014

18

or receiver) and wouldn’t be released until the system is actually dismantled later on in the disposal 

process (Oko-Recherche 2003). 

Because anticipated occupational exposures could be above the exposure limits for HFO-1234ze(E) for the 

direct rack system and commercial ice machine disposal release scenarios, the recommendations for proper 

engineering controls and PPE in the MSDS for R-450A should be followed. Adequate ventilation should 

always be established during any use, handling, or storage of R-450A. If recovery and disposal is taking 

place in an enclosed space without any mechanical ventilation, facilities should be cleared of non-essential 

personnel and technicians should wear a SCBA and other appropriate protective equipment. 

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, mechanical-resistance gloves (e.g., oilrepellent or thermal resistant gloves) when handling cylinders and chemically-resistant gloves when 

handling the gas mixture (e.g., butyl rubber, chlorinated polyethylene, or neoprene). For larger retail food 

refrigeration (e.g., rack systems) and commercial ice machine (e.g., remote systems) systems, toxicity risks 

could be further minimized through the installation of signage which warns room occupants to remain 

standing (as higher concentrations are likely to accumulate near the floor) and not to enter recessed parts of 

the facility (e.g., maintenance crawl spaces and below grade service areas) and exit the facility

immediately should they hear the refrigerant detector alarm and/or smell the leaked refrigerant . 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 retail food refrigeration units, 

commercial ice machines, and vending machines.

11. 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 retail food refrigeration, vending machines, and 

commercial ice machines. 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, R450A 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

19

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