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Significant New Alternatives Policy Program 

Refrigeration and Air Conditioning Sector

Risk Screen on Substitutes in Household Refrigerators and Freezers and Water 

Coolers

Substitute: R-513A (Opteon® XP10)

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-513A (also known as Opteon® XP10) as a substitute in the household 

refrigerator and freezer end-use and the drinking water cooler end-use. Table 1 presents the composition of 

the proposed substitute. 

Table 1. Composition of R-513A and Potential Impurities

Constituent Chemical Formula CAS Number Concentration

(Weight Percent)

2,3,3,3-Tetrafluoropropene (HFO-1234yf) CH2CFCF3 754-12-1 ≤56%

1,1,1,2-Tetrafluoroethane (HFC-134a) CF3CH2F 811-97-2 ≤44%

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: 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 
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• Section 11: General Population Exposure Assessment

• Section 12: References

2. SUMMARY OF RESULTS

R-513A is recommended for SNAP approval for household refrigerators and freezers and water coolers. 

EPA's risk screen indicates that the use of the proposed substitute will be less harmful to the atmosphere 

than the continued use of ODS and other commonly used refrigerants, as it is less harmful to the ozone 

layer, has lower climate impact, and a shorter atmospheric lifetime. The components of R-513A are not 

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. In addition, because R-513A is 

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

It is expected that the manufacturer’s safety data sheet (SDS) for R-513A and good manufacturing 

practices will be adhered to during handling or use of R-513A.

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 household 

refrigerators and freezers and water coolers using R-513A. Because household refrigerators and freezers 

and water coolers are to be installed in locations with adequate space and/or ventilation in accordance with 

EPA recommendations and the equipment maintenance manuals for R-513A in each end-use, significant 

toxicity risk to consumers is also unlikely. 

Additional safeguards, including specified refrigerant concentration limits (RCL) of R-513A components, 

are also provided by adherence to industry standards including American Society of Heating, Refrigerating 

and Air-Conditioning Engineers (ASHRAE) Standards 15,

1 34,2 and 62.3

3. ATMOSPHERIC ASSESSMENT

This section presents an assessment of the potential risks to atmospheric integrity posed by the use of R513A in household refrigerators and freezers and water coolers. 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 ALT when compared to refrigerants such as CFC-12, R-502, and HCFC-22. In addition, R-513A 

has lower climate impact and a shorter ALT than those predicted for other substitutes examined in the 

Background Document as well as commonly utilized refrigerant HFC-134a. Thus, EPA believes that the 

use of R-513A would result in substantially less harm to the climate and ozone layer than the continued 

use of ODS and other commonly used refrigerants. 

 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 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.
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Table 2. Atmospheric Impacts of R-513A Components Compared to Other Refrigerants Used in 

Household Refrigerators and Water Coolers

Refrigerant Ozone Depleting Potential

(ODP)a

Global Warming Potential

(GWP)b

Atmospheric Lifetime in 

Years (ALT)b

R-513A 0 631 NAc

Individual Components

HFC-134a 0 1,430 14

HFO-1234yf 0 4d 11 daysd

CFC-12 0.82 10,900 100

R-502e 0.2 4,650 NAf

HCFC-22 0.13 1,810 12a

HFC-134a 0 1,430 14 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 the individual components 

are listed in the table. 

d Papadimitriou et al. (2007) 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]).

4. VOLATILE ORGANIC COMPOUND ASSESSMENT

The components of R-513A, HFC-134a and HFO-1234yf, are exempt from the definition of VOCs under 

CAA regulations (40 CFR 51.100(s)). Therefore, VOC impacts from the release of R-513A are not a 

concern.

5. DISCUSSION OF END-USE SCENARIOS MODELED

The submitter states that R-513A household refrigerators and freezers will have a typical charge size of 

100 grams and a maximum charge size of 1,000 grams. Water coolers are expected to have a typical 

charge size of 100 grams and a maximum charge size of 500 grams. The intended maximum and typical 

charge sizes for all of the proposed applications are listed in Table 3. 

Table 3. Typical and Maximum Charge Sizes for Various R-513A End-Uses and Applications

End-Use Typical Charge 

Size (grams)

Maximum Charge 

Size (grams)

Household Refrigerators and Freezers 100 1,000

Water Coolers 100 500

Household refrigerators and freezers and water coolers can be installed in a wide range of locations with 

varying room volumes (e.g., residential homes, commercial office buildings). Because the typical and 

maximum charge sizes for household refrigerators and freezers (i.e., 100 to 1,000 grams) encompasses the 

typical and maximum charge sizes for water coolers (i.e., 100 to 500 grams), the reasonable worst-case 

scenario for this analysis assumes that a catastrophic leak of refrigerant occurs while a household 

refrigerator is installed at the end-use (i.e., a small kitchen) for both the typical and maximum charge size 

provided by the submitter (e.g., 100 grams and 1,000 grams, respectively). The analysis in this risk screen 

conservatively assumes that the household refrigerator is located in a small residential kitchen with an 

effective volume of 18 m3 (640 ft3

) (i.e., excluding the space filled by cabinets, other kitchen equipment, 

etc.) and a height of 2.44 meters. This location also represents a likely installation location for water 

coolers.

Under the reasonable worst-case scenario, the full charge of the unit is assumed to be emitted into the 

kitchen with 2.3 air changes per hour (ACH) over the course of two time durations: 1) one minute, which 
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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, pinhole leaks). The one-minute time duration is most 

appropriate for flammable refrigerants and presents a less relevant scenario for R-513A, which is 

nonflammable. Therefore, while we evaluate both of these scenarios 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-513A in household refrigerators and freezers 

and water coolers. A vertical concentration gradient is also assumed since R-513A is denser than air (i.e., 

the specific gravities of both HFC-134a and HFO-1234yf are greater than 1) and will settle in higher 

concentrations closer to the ground. In order to simulate the vertical concentration gradient of refrigerant 

following release, it is assumed that 95 percent of the leaked refrigerant mixes evenly into the bottom 0.4 

meters (1.3 feet) of the room, and the rest of the refrigerant mixes evenly in the remaining volume 

(Kataoka 2000). Additionally, because the average breathing zone is above 0.4 meters and mixing is likely 

to occur upon release of R-513A from the unit because the system pressure is higher than the surrounding 

atmospheric pressure, the absence of the vertical concentration gradient was also evaluated in the end-use 

exposure assessment (Section 9). Table 4 details the end-use modeling assumptions used throughout the 

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

Table 4. End-Use Scenario Model Assumptions 

Parameter Assumption

Room Type Household Kitchen

Size (m3) 18a (640 ft3)

Ventilation Rate (air changes per hour) 2.3a

Refrigeration Unit Household Refrigerator

Charge Size (g) 100b; 1,000c

Duration of Release (minutes) 1d; 15e

Vertical Concentration Gradient Yes; No

 a Background Document (EPA 1994)

 b Typical charge size for household refrigerators and freezers and water coolers (DuPont Fluoroproducts 2014b) c The maximum charge size for household refrigerators and freezers is 1,000 grams, which is greater than the maximum 

charge size for water coolers of 500 grams, and is more conservative for this end-use scenario (DuPont Fluoroproducts 

2014b). d Represents catastrophic release due to puncture and/or destruction of system

e Represents non-catastrophic release due to leak in the system (e.g., valve failure, pinhole leak)

EPA recognizes that household refrigerators and freezers and water coolers may be placed in a variety of 

locations with differing room 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 household refrigerators and freezers and water coolers, 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 R-513A in these end-uses 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 household refrigerators and 

freezers and water coolers, EPA identified the relevant toxicity threshold values for comparison to 

modeled exposure concentrations for different scenarios. According to ASHRAE Standard 34-2013, R513A is listed under safety group A1 with a RCL of 72,000 ppm (ASHRAE 2015). 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 a refrigeration unit (ASHRAE 2010b). ASHRAE Standard 15 implements the 

aforementioned standard, requiring that “the concentration of refrigerant in an enclosed space following a 
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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-513A in addition to the hypoxia no observed adverse 

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

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), such as Workplace 

Environmental Exposure Levels (WEELs). 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-513A, potential short-term, end-use exposures were evaluated 

on a component basis (i.e., HFC-134a and HFO-1234yf). Table 5 lists the relevant toxicity limits for R513A 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-513A Components

R-513A

Component

WGL

(Long-term Exposure)

Ppm

EGL 

(Short-term Exposure)

ppm

Refrigerant Concentration 

Limit (RCL)

ppm

R-513A 653 (8-hour AEL) 1,960 (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-1234yf 500 (8-hour WEEL) 1,500 (15-min STEL)b 100,000c

a Neither the American Conference of Governmental Industrial Hygienists (ACGIH) nor the American Industrial Hygiene Association (AIHA)

recommend ceiling or short term exposure limits for the blend R-513A. A STEL for R-513A of 1,960 ppm was developed by EPA based on the 

653 ppm acceptable exposure limit (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 = 653 ppm x 3 ≈ 1,960 ppm b Neither ACGIH nor AIHA recommend ceiling or short term exposure limits for HFO-1234yf. A STEL for HFO-1234yf of 1,500 ppm was 

developed by EPA based on the 500 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 = 500 ppm x 3 ≈ 1,500 ppm c Although a RCL has not been proposed for HFO-1234yf, the recommended acute toxicity exposure limit (ATEL) for HFO-1234yf is 101,000 

ppm (DuPont Fluoroproducts 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.
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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.

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 

threshold limit value-time-weighted value (TLV–TWA), set by ACGIH. 

AEGLb,c

Acute Exposure Guideline 

Level 1

AEGL-1 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 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 TWA exposure limit set by OSHA. 

AEL Acceptable Exposure Limit The maximum 8-hour 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 SDS, exposure to R-513A may be hazardous if inhalation, skin contact, or eye contact 

with the proposed substitute occurs. The most likely pathway of exposure is through inhalation. R-513A

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 over-exposure (i.e., oxygen levels fall below 6 percent by volume), death may occur. 

If inhaled, R-513A can cause symptoms such as light-headedness, dizziness, confusion, incoordination, 

drowsiness, unconsciousness, and anesthetic effects. Excessive inhalation of R-513A may also result in an

irregular heartbeat or death, due to cardiac effects. Furthermore, R-513A vapors are denser than air and can 

cause asphyxiation if the oxygen concentration in a room is significantly reduced. 

If R-513A is inhaled, person(s) should be immediately removed from the contaminated space and exposed 

to fresh air. In accordance with the SDS, EPA further recommends that if breathing is difficult or irregular, 

person(s) should be given oxygen, provided a qualified operator is present, and medical attention be 
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sought. Exposures of R-513A to the skin may cause frostbite. In the case of dermal exposure, the SDS for 

R-513A 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-513A to the eyes could cause eye irritation. In case of ocular exposure, the

SDS for R-513A 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 

potential health effects of R-513A can be minimized by following the exposure guidelines and ventilation 

and PPE recommendations outlined in the SDS for R-513A and this risk screen.

7. FLAMMABILITY ASSESSMENT

R-513A is classified as an A1 refrigerant by ASHRAE, and is considered to be nonflammable (DuPont 

Fluoroproducts 2014a; ASHRAE 2015). Based on this classification, manufacture, servicing, and use of R513A is not expected to present a flammability risk in household refrigerators and freezers and water 

coolers.

8. ASPHYXIATION ASSESSMENT

The risk of asphyxiation for the reasonable worst-case scenario described in Section 5 was investigated for 

R-513A. 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 at which an asphyxiation risk could occur in the room size 

specified in the worst-case scenario (i.e., charge sizes greater than this are expected to cause an 

asphyxiation risk), and 3) performing a threshold analysis of the maximum room size at which an 

asphyxiation risk could occur with the charge size specified in the worst-case scenario (i.e., room sizes 

smaller than this are expected to cause an asphyxiation risk). 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

Scenario Charge Size 

(g)

Effective Room Size 

(m3)

Percent Oxygen 

Concentration in Lower 

0.4 Meters

Reasonable Worst-Case 1 100 18 (640 ft3) 21%

Reasonable Worst-Case 2 1,000 18 (640 ft3) 21%

Threshold Analysis 1a: Charge Size 5,630 18 (640 ft3) 12%

Threshold Analysis 2a: Room Size 100 0.32 (11.3 ft3) 12%

Threshold Analysis 2b: Room Size 1,000 3.2 (113 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).
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In order for a risk of asphyxiation to occur, the normal concentration of oxygen in air (21 percent) must be 

reduced to 12 percent.4 Based on the reasonable worst-case scenario modeling, a release of R-513A from 

household refrigerators has an insignificant impact on the concentration of oxygen in the air and therefore 

does not present a significant risk of asphyxiation. This 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; therefore, the actual asphyxiation 

risk to person(s) is likely to be even smaller than modeled.

For the asphyxiation threshold analyses shown in Table 7, the conditions at which an asphyxiation concern 

would exist were determined. Within the reasonable worst-case room size of 18 m3 (640 ft3

), as shown 

under Threshold Analysis 1a, the charge size of the R-513A refrigerator would have to be at least 5,630 

grams for asphyxiation to be a concern, which is more than 5 times the maximum charge size anticipated 

by the submitter for household refrigerators and freezers (or more than 11 times the maximum charge size 

anticipated for water coolers). In Threshold Analyses 2a and 2b, the volume of the room would have to be 

0.32 m3 (11.3 ft3

) and 3.2 m3 (113 ft3) or smaller for asphyxiation to be of concern for units with 100-gram 

and 1,000-gram charge sizes, respectively.

Based on the worst-case modeling results and threshold analysis, EPA does not believe that the use of R513A in household refrigerators and freezers or water coolers poses a significant risk of asphyxiation or 

impaired coordination to end-users or servicing technicians, provided systems are installed in appropriate 

spaces according to guidelines from the manufacturer and the SDS for R-513A.

9. END-USE EXPOSURE ASSESSMENT

This section presents estimates of potential end-user exposures to R-513A and each of its components in 

the event of a catastrophic release from the proposed substitute’s use in household refrigerators and 

freezers and water coolers. An end-use exposure analysis was performed to examine potential catastrophic 

releases of R-513A 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 a household refrigerator were examined. As discussed in 

Section 5, the full charge of the unit is assumed to be emitted over the course of 1 minute and 15 minutes, 

where the latter scenario more accurately represents a reasonable worst-case scenario for R-513A in 

household refrigerators and freezers, because R-513A is nonflammable. The analysis was undertaken to 

determine the 15-minute exposures for R-513A, which were then compared to the standard toxicity limits 

presented in Table 5 to assess the risk to end-users. 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. Because 

HFO-1234yf is present in larger concentrations and because it has a lower exposure limit than HFC-134a, 

Table 8 only displays exposures for HFO-1234yf, the component with greater potential concerns. 

 4 Twelve percent oxygen in air is the NOAEL for hypoxia (ICF 1997).
Final—July 2, 2015

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Table 8. End-Use Exposure Assessment for HFO-1234yf Componenta

Scenario Charge 

Size (g) Room Size (m3)

Vertical 

Concentration 

Gradient

Duration 

of 

Release 

(min)

15-min TWA 

End-Use 

Exposure 

(ppm)b

15-min 

Short 

Term 

Exposure 

Limits 

(ppm)

Acute 

Toxicity 

Exposure 

Limit 

(ATEL)

(ppm)

Reasonable Worst-Case Scenario 1a

100 18 (640 ft3)

Yes 1 2,880

1,500 101,000b

Reasonable Worst-Case Scenario 1b No 1 480

Reasonable Worst-Case Scenario 1c Yes 15 1,680

Reasonable Worst-Case Scenario 2a

1,000 18 (640 ft3)

Yes 1 28,800

Reasonable Worst-Case Scenario 2b No 1 4,800

Reasonable Worst-Case Scenario 2c Yes 15 16,800

Threshold Analysis 1: Charge Size 52 18 (640 ft3)

Threshold Analysis 2a: Room Size 100 35 (1,130 ft Yes 1 1,500 3)

Threshold Analysis 2b: Room Size 1,000 350 (11,300 ft3)

Bold font indicates modeling results. a Cells highlighted in green are the scenarios with acceptable exposure levels given various modeling assumption options. b ATEL for HFO-1234yf is 101,000 ppm; see Table 5 for more information.

Under the reasonable worst-case scenario described in Section 5 for household refrigerators and freezers 

and water coolers, catastrophic releases of the typical and maximum charge size of R-513A in a household 

refrigerator were modeled. The modeling scenarios evaluate the presence and absence of a vertical 

concentration gradient as well as two refrigerant release time durations (i.e., 1 minute and 15 minutes). The 

anticipated 15-minute TWA exposures of the HFO-1234yf component of R-513A do exceed its STEL (i.e., 

1,500 ppm) for all scenarios except Reasonable Worst-Case Scenario 1b, which does not assume the 

presence of a vertical concentration gradient. 

Although most of the exposure estimates for the reasonable worst-case scenarios exceed the STEL of 

HFO-1234yf (i.e., 1,500 ppm) (see Table 8), the STEL is a conservatively-derived exposure limit that is 

intended to protect workers in an occupational setting in which they are exposed to these chemicals on a 

daily basis (see Table 5). The STEL values do not represent limits for a single exposure in a lifetime. 

These modeled exposures are one-time exposures, so exceedances of the STEL values do not necessarily 

indicate a significant risk of harm to consumers. The effect of a one-time exposure can be more accurately 

evaluated by comparing the modeled exposure concentrations to the ATEL for HFO-1234yf, which is a

limit intended to reduce the risks of acute toxicity hazards in normally occupied, enclosed spaces 

according to ASHRAE Standard 34 (see Table 5). All of these exposure estimates are significantly lower 

than the ATEL of 101,000 ppm for HFO-1234yf. Furthermore, the estimated exposures for R-513A in 

each of these scenarios are also significantly lower than the RCL for R-513A (i.e., 72,000 ppm).

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

room volume, low ventilation rate) that do not necessarily reflect the actual room attributes where R-513A

household refrigerators and freezers and water coolers will be installed. Specifically, Reasonable WorstCase Scenarios 1a through 1c model a 100-gram refrigerator, which represents an average refrigerator size 

(i.e., 20 – 25 ft3 capacity), in a fairly small kitchen size that would likely contain a smaller refrigerator 

(e.g., 10 ft3 capacity). In addition, a 1,000-gram refrigerator represents a high-end, commercial-sized 

refrigerator, that is generally installed in large homes (i.e., greater than 5,000 ft2 or 465 m2

) and are 

therefore unlikely to be installed in a kitchen with an effective volume of 18 m3 (640 ft3

). Furthermore, 

kitchen spaces are often connected to other rooms through open pathways without doors (e.g., an eat-in 

space or a dining area in an open floor plan home), which would increase the effective volume of the space 

into which a refrigerant would be released, thereby reducing the likelihood that end-users would be 

exposed to modeled concentrations. 
Final—July 2, 2015

10

Finally, the exposures assuming a vertical concentration gradient represent concentrations of leaked 

refrigerant in the bottom 0.4 meters (1.3 feet) of the room, accounting for 95 percent of the refrigerant 

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

portion (e.g., prone or supine on the floor or crawling infant) in the event of the catastrophic release of 

refrigerant is low. Furthermore, although children may be at increased risk because of their short stature 

when the proposed substitute is found at higher concentrations in the lower compartment of the room, the 

probability that they are present in the location in which a catastrophic release of the entire charge of the 

household refrigeration system is low.

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

proposed RCL for R-513A (i.e., 72,000 ppm or 320 g/m3

) is not exceeded in any location where an R513A system is installed, unless proper leak protection devices are in place in order to prevent exposures 

of R-513A beyond the recommended limits. Proper leak protection devices, engineering control 

requirements, and adherence to the SDS 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, installation and servicing, and 

disposal of R-513A household refrigerators and freezers and water coolers. To ensure that use of the 

proposed substitute in household refrigeration units 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 EPA’s 

Vintaging Model.5

 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. For charging, servicing, and disposal activities, the release rate per event was 

multiplied by the number of events estimated to occur over a workday. During charging and servicing, the 

release per event was conservatively assumed be 0.4 percent of the equipment charge. For equipment 

charging and servicing, the number of events per workday was conservatively assumed that eight events of 

servicing a unit by one servicing technician occur in an 8-hour work day (see Section 10.2). 

For disposal, the release per event was conservatively assumed to be 100 percent of the equipment charge 

(representing a catastrophic release). It was assumed that 10 units are disposed of during an 8-hour work 

day; however, it was assumed that of the 10 units, only the last unit per workday would experience the 

catastrophic release (i.e., 100 percent). The remaining 9 units were assumed to release an incidental 

amount of refrigerant (i.e., 1 percent per unit) from the connecting and disconnecting of lines, as it is likely 

that if a worker was exposed to the entire charge of a system during disposal activities, they would 

immediately stop working, clear the area until all refrigerant has been removed from the space (e.g., 

through ventilation), and adhere to the exposure procedures recommended in the SDS for the proposed 

substitute (see Section 10.3).

The modeled exposure concentrations were compared to short-term occupational exposure limits at 

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

 5 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—July 2, 2015

11

10.1 Occupational Exposure at Manufacture

During manufacture of the components and blending of R-513A, the SDS for both HFC-134a and HFO1234yf should be referenced and proper engineering controls and PPE used. 

Refrigerant quality control testing may also result in release of de minimus quantities of refrigerant, which 

would typically be to exhaust ducts or fume hoods. 

To prevent significant exposure if such leaks occur, engineering controls should be used, including normal 

and local ventilation (e.g., chemical hoods) and vapor-in-air detection 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 self-contained breathing apparatus [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-1234yf 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 SDS for R-513A and its 

components, there is no significant risk to workers during the manufacture of R-513A.

10.2 Occupational Exposure at Charging and Servicing

Household refrigerators and freezers and water coolers would typically be charged by the Original 

Equipment Manufacturer (OEM). During OEM system manufacture (i.e., charging at OEM 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. Release points during charging would be connection/disconnection of temporary lines from 

charging equipment. 

Charging and servicing activities for household refrigerators and freezers and water coolers are not 

expected to result in significant worker exposure when certified technicians follow the procedures outlined 

in the R-513A SDS 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 TWA exposures for each R-513A constituent were estimated for the 

charging and servicing exposure scenarios and compared to their respective STELs (see Table 9). The 

modeling results indicate that the maximum anticipated occupational exposure concentrations at no point 

exceed the short-term exposure limit for either component.

Table 9. Occupational Risk Assessment at Servicinga

Component 15-minute TWA Occupational Exposure (ppm) Short Term Exposure 

Charge Size: 100 grams Charge Size: 1,000 grams Limits (ppm)

HFC-134a 0.20 2.0 8,000b

HFO-1234yf 0.23 2.3 1,500c

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 10-minute and 30-minute AEGL-1; see Table 5 for more information. c EPA-derived 15-minute STEL; see Table 5 for more information. 

The estimated exposures were derived using conservative assumptions, and represent a reasonable worstcase scenario with a low probability of occurrence. These types of systems are typically serviced by 
Final—July 2, 2015

12

trained personnel using proper industrial hygiene techniques and proper engineering controls (e.g., local 

ventilation, refrigerant detectors, and alarm systems). Thus, EPA does not believe that installation or 

servicing of household refrigerators and freezers and water coolers containing R-513A presents a 

significant concern to workers.

10.3 Occupational Exposure at Disposal

Disposal of R-513A household refrigerators and freezers and water coolers is expected to occur with 

limited frequency (up to approximately ten disposal events per day) at disposal facilities 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). 

Table 10 displays the maximum estimated 8-hour TWA occupational exposure levels for each component 

of R-513A during disposal. To model a worst-case scenario, it was assumed that of the 10 disposal events, 

9 units are properly disposed of with only incidental releases of refrigerant (i.e., 1 percent per unit) 

followed by the disposal of one unit that results in a catastrophic release of refrigerant (i.e., 100 percent of 

the equipment charge). Because modeled exposure levels for both the typical and maximum charge sizes 

are significantly lower than the 8-hour exposure limits for each component, occupational exposure to the 

proposed substitute during disposal is not considered a toxicity risk. Further, estimated exposures were 

derived using conservative assumptions (e.g., no ventilation or use of PPE assumed) and represent a worstcase scenario with a low probability of occurrence. These types of systems are typically disposed of by 

trained personnel using proper industrial hygiene techniques.

Table 10. Occupational Risk Assessment at Disposala

Component 8-hour TWA Occupational Exposure (ppm) 8-Hour Long Term 

Charge Size: 100 grams Charge Size: 1,000 grams Exposure Limits (ppm)

HFC-134a 7.3 73 1,000b

HFO-1234yf 8.3 83 800b

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 8-hour WEEL

Although anticipated occupational exposures are well below the exposure limits for both R-513A 

components for both typical and maximum charge sizes, the recommendations for proper engineering 

controls and PPE in the SDS for R-513A should be followed. Adequate ventilation should always be 

established during any use, handling, or storage of propane. Engineering controls should include vapor-in 

air detection systems and local exhaust ventilation during use of R-513A to prevent dispersion throughout 

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

locations where R-513A 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 SDS for R-513A, there is no significant risk to workers during the 

manufacturing, installation, servicing, and disposal of R-513A in household refrigerators and freezers and 

water coolers.

11. GENERAL POPULATION EXPOSURE ASSESSMENT
Final—July 2, 2015

13

R-513A 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 household refrigerators and freezers and water coolers. 

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-513A is a gas and, 

therefore, releases to ground or surface water are not anticipated, as R-513A 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-513A). Should air releases during 

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

collect R-513A and prevent the release of R-513A to the atmosphere. EPA believes that by using proper 

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

proposed substitute’s SDS and this risk screen, exposure to R-513A is not expected to pose a significant 

toxicity risk to the general population.
Final—July 2, 2015

14

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