Final—July 2, 2015

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Significant New Alternatives Policy Program 

Refrigeration and Air Conditioning Sector

Risk Screen on Substitutes in Refrigerated Transport

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 refrigerated 

transport end-use, specifically in trucks and trailers. 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 Scenarios Modeled 

• Section 6: Potential Health Effects 

• Section 7: Flammability Assessment

• Section 8: Asphyxiation Assessment 

• Section 9: End-Use Exposure Assessment
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• Section 10: Occupational Exposure Assessment 

• Section 11: General Population Exposure Assessment

• Section 12: References

2. SUMMARY OF RESULTS

R-513A is recommended for SNAP approval for the refrigerated transport end-use, specifically in trucks 

and trailers. 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, and 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, servicing, and disposal of refrigerated transport units

using R-513A. 

In addition, it is expected that leak detectors will be installed inside refrigerated transport containers and 

container doors will be open during end-use to prevent significant exposure to R-513A in the case of 

catastrophic leakage. Because refrigerated transport units are to be installed in locations with adequate 

space and/or ventilation (i.e., outdoors) in accordance with EPA recommendations and the equipment 

maintenance manuals for R-513A in the refrigerated transport end-use, significant toxicity risk to 

consumers is also unlikely. 

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

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 refrigerated transport. 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 CFC-12, R-502, and HCFC-22. In addition, R-513A also has lower 

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

Document, as well as commonly utilized refrigerants in refrigerated transport, HFC-134a, R-404A, R507A, and R-407C. 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.
Final—July 2, 2015

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

Refrigerated Transport

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 100b

R-502e 0.2 4,650 NAf

HCFC-22 0.13 1,810 12a

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-1234yf is 11 days (IPCC 4th Assessment Report [Forster et al. 2007], Papadimitriou et al. (2007)). 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]).

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 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

R-513A has been proposed for use in refrigerated transport units. As provided by the submitter, the typical 

and maximum charge sizes for R-513A in trucks and trailers are listed in Table 3. 

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

End-Use Application Typical Charge Size

(kg)

Maximum Charge Size

(kg)

Refrigerated 

Transport

Trucks 2 5

Trailers 7 15

To evaluate potential end-use exposures for R-513A in refrigerated transport units, this risk screen 

examines a scenario in which a catastrophic leak of refrigerant occurs while personnel are inside the 

refrigerated transport container and the doors to the container are closed. A more reasonable worst-case 

scenario for this assessment would consider the catastrophic leak of refrigerant occurring while the 

container doors are open, because EPA expects the refrigerated container doors to be open while personnel 

are present inside the container at end-use (e.g., during loading and unloading of refrigerated goods). 

However, the limitations of the box model used for this assessment do not allow consideration of this 
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scenario; calculating the concentration of R-513A in the container as it exchanges with the warm, outside 

air through the open door would require more complex computational fluid dynamics modeling. 

Given these limitations, the risk screen evaluates a more unlikely scenario, in which it is assumed that the 

full charge of the refrigerated transport unit is emitted over the course of one minute into the refrigerated 

container with the door closed. Although R-513A is denser than air, a vertical concentration gradient is not 

assumed, because when the full charge is released, the presence of ventilation and the high pressure 

operating conditions of the refrigerant are expected to disperse the proposed substitute evenly and 

immediately throughout the refrigerated transport container. It is assumed that an individual is present at 

the start of the leak and remains in the container until the charge is completely released.

Furthermore, this risk screen evaluates a refrigerated transport unit with a ventilation rate of 25 m3

/hr, a 

lower ventilation rate appropriate for less perishable produce (perishable items require a higher ventilation 

rate up to 60 m3

/hr) (Brecht et. al 2000). Hence, based on suggested ventilation rates for refrigerated 

transport units for various types of produce, this analysis conservatively assumes a ventilation rate of 25 

m3

/hr.4 Table 4 details the end-use modeling assumptions used in Sections 8 and 9.

Table 4. End-Use Scenario Model Assumptions 

Parameter Assumptions

(Trucks)

Assumptions

(Trailers)

Refrigerated Transport Container Trucks Trailers

Charge Size (kg) 2; 5 7; 15

Length of Release (minutes) 1 1

Container Size (volume - m3) 78 (2,760 ft3)a 100 (3,530 ft3)b

Room Ventilation (m3/hr) 25 25

Vertical Concentration Gradient No No a Specific information was not available regarding the sizes of the refrigerated transport trucks. Thus, a standard 26 ft.

(7.9 m) refrigerated truck was used for this scenario, with a height of 12.5 ft (3.8 m) and a width of 8.5 ft (2.6 m)

(C.H. Robinson, 2012). b According to the United Nations Environmental Programme (UNEP), trailers have box volumes of approximately 100 

m3 (UNEP 2010).

EPA recognizes that refrigerated transport units may be placed in a variety of containers with different 

sizes and ventilation rates. When units are installed in smaller containers, there is a higher risk for 

asphyxiation or significant exposure. To address this variability in container volumes and charge sizes for

refrigerated transport units, this risk screen incorporates threshold analyses in addition to the worst-case 

scenario modeling. The threshold analyses are performed in order to determine the container size and 

charge size requirements that ensure that the use of R-513A in refrigerated transport 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 refrigerated transport end-uses, 

EPA identified the relevant toxicity threshold values for comparison to modeled exposure concentrations 

for different scenarios. According to ASHRAE Standard 34-2013, R-513A 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 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 

 4 Ventilation rates range from 0 to 60 m3/hr depending on the type of good that is transported (Hamburg Süd 2010). 
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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 (WGL), such as Workplace 

Environmental Exposure Levels (WEELs). Risks from potential short-term consumer exposures were 

evaluated by comparing exposure concentrations to emergency guidance levels (EGL). In the absence of 

an established short-term exposure limit (STEL), acute exposure guideline level (AEGL), or emergency 

response planning guideline (ERPG) for R-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 101,000c

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 AEL value. The STEL was estimated as three to five times the acceptable exposure limit (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 an RCL has not been proposed for HFO-1234yf, the recommended ATEL for HFO-1234yf is 101,000 ppm (DuPont Fluoroproducts

2014).

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 
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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 

threshold limit value-time weighted average (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. 

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 

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 
Final—July 2, 2015

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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 2014; ASHRAE 2015). Based on this classification, manufacture, servicing, and use of R513A is not expected to present a flammability risk in the refrigerated transport end-use.

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 maximum charge size and container size specified in the worst-case scenario, 2) 

performing a threshold analysis of the minimum charge size needed to cause an asphyxiation risk in the 

room size specified in the worst-case scenario, and 3) performing a threshold analysis of the minimum

container size needed to cause an asphyxiation risk with the maximum charge size specified in the worstcase 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 container doors, which allow 

air to flow in and out. As specified in Section 5, the worst-case scenario does not assume 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 realworld conditions. The results of the asphyxiation assessment are summarized in Table 7 below. 

Table 7. Asphyxiation Assessmenta

Refrigerated 

Transport Application Scenario Charge Size (kg)

Effective 

Container Size 

(m3)

Percent 

Oxygen 

Concentrationb

Trucks Scenario 1a: Maximum Charge Size 5 78 (2,760 ft3) 21%

Trailers Scenario 1b: Maximum Charge Size 15 100 (3,530 ft3) 20%

Trucks Threshold Analysis 1a: Charge Size 150 78 (2,760 ft3)

12% Trailers Threshold Analysis 1b: Charge Size 190 100 (3,530 ft3)

Trucks Threshold Analysis 2a: Container Size 5 2.6 (93 ft3)

Trailers Threshold Analysis 2b: Container Size 15 7.9 (280 ft3)

Bold font indicates modeling results. a Cells highlighted in green are the scenarios in which the charge and container 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).

In order for a risk of asphyxiation to occur, the normal concentration of oxygen in air (21 percent) must be 

reduced to 12 percent.5 Based on the worst-case scenario modeling for R-513A, a release of the maximum 

charge sizes indicated by the submitter in trucks and trailers (i.e., 5 kg and 15 kg, respectively) does not 

present a significant risk of asphyxiation. This modeling does not take into account any ventilation which 

is likely to occur, such as open container doors that allow air to flow in and out, as mentioned above. Thus,

the actual asphyxiation risk to personnel is likely to be even smaller than modeled. 

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

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

would exist were determined. 

• Within a container size of 78 m3 (2,760 ft3

), as shown under Threshold Analysis 1a, the charge size 

of the R-513A refrigerated truck unit would have to be at least 150 kg for asphyxiation to be a 

concern, which is more than thirty times greater than the maximum charge size indicated by the 

submitter for trucks (i.e., 5 kg). 

• As shown under Threshold Analysis 1b, the charge size of the R-513A refrigerated trailer unit in a 

100 m3 container would have to be at least 190 kg for asphyxiation to be a concern, which is 

approximately thirteen times greater than the maximum charge size indicated by the submitter for 

trailers (i.e., 15 kg).

• In order for a risk of asphyxiation to occur from the release of a 5 kg refrigerated truck unit, the 

volume of the container would have to be approximately 2.6 m3 (93 ft3

), or approximately thirty 

times smaller than the typical truck size indicated by the submitter (see Threshold Analysis 2a).

• Using the largest charge size of 15 kg for refrigerated trailers, as shown under Threshold Analysis 

2b, the volume of the container would have to be approximately 7.9 m3 (280 ft3

), or approximately 

thirteen times smaller than the typical trailer container size indicated by the submitter for 

asphyxiation to be of concern. 

Based on the modeling results and threshold analysis in Table 7, EPA does not believe that the use of R513A in refrigerated transport 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 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 chemical 

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

transport units. An end-use exposure analysis was performed to examine potential catastrophic releases of 

R-513A under the scenario outlined in Section 5.

This end-use exposure assessment examines a scenario in which personnel are located inside the 

refrigerated transport unit containing goods; such scenarios are expected to occur while the container doors 

are open. When the container doors are opened, a stack effect exists from the presence of the denser, cold 

air coming into contact with the warm, moist air outside. This effect will cause the colder air to flow 

outside of the container and become replaced by the warm, outside air through infiltration. Therefore, EPA 

expects that if a release of the proposed substitute occurs while personnel are present inside the 

refrigerated transport container (e.g., during loading and unloading of refrigerated goods), the container 

doors would be open, increasing the air exchange rate inside of the unit and also resulting in diffusion of 

any R-513A to flow towards the outside of the container.

To simulate a worst-case scenario, the catastrophic release of the entire charge of the unit into the 

refrigerated container was modeled. The estimated exposures are conservative, as the analysis assumes that 

a catastrophic release occurs while the refrigerated transport container doors are closed and also does not 

consider other variables that would reduce the levels to which individuals would be exposed. 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. Because HFO-1234yf is 

present in larger concentrations and because it has a lower exposure limit than HFC-134a, Tables 8a and 

8b only display exposures for HFO-1234yf, the component with greater potential concerns. Modeling 

results are presented in Table 8a.
Final—July 2, 2015

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

Refrigerated 

Transport 

Containers

Scenario Charge 

Size (kg)

Container 

Size (m3) Component

15-min TWA 

End-Use 

Exposure 

(ppm)

Exposure Limit (ppm)b

Short-term 

(15-min) 

Acute 

Toxicity

Trucks Worst-Case Scenario 1a 2 78

HFO-1234yf

2,690

1,500c 101,000 Worst-Case Scenario 1b 5 6,720

Trailers Worst-Case Scenario 1c 7 100 7,460

Worst-Case Scenario 1d 15 15,990

Bold font indicates modeling results. a Cells highlighted in green are the scenarios in which the charge and container sizes evaluated in this risk screen are acceptable given various 

modeling assumptions. b See Table 5 for more information c EPA-derived STEL (see Table 5).

Under the worst-case scenarios described in Section 5 for refrigerated transport systems in trucks and 

trailers, catastrophic releases of the typical and maximum charge sizes of R-513A were modeled. 

Although the exposure estimates for the reasonable worst-case scenarios exceed the STEL for the HFO1234yf component (i.e., 1,500 ppm) (see Table 8a), 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. The STEL values do not represent limits for a single exposure in a lifetime. These 

modeled exposures are one-time exposures following a catastrophic release of refrigerant so exceedances 

of the STEL values do not necessarily indicate a significant risk of harm to end-users. The effect of a onetime exposure can be more accurately evaluated by comparing the modeled exposure concentrations to the 

ATEL, 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 6). All of the modeled 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). Because the modeling was done using a conservative worst-case scenario where the 

refrigerated transport container doors are closed, and because normally personnel would be exposed in a 

situation where the container doors are open with significantly higher ventilation levels, personnel 

exposure to the proposed substitute at end-use is not expected to reach the modeled concentrations shown 

in Table 8a. Therefore, end-use exposure is not considered to be a significant risk. 

A threshold analysis was performed to determine the combinations of charge sizes and container sizes with 

a 25 m3

/hr ventilation rate that would avoid end-use exposures above the STEL for HFO-1234yf (i.e., 

1,500 ppm). The results from the threshold analyses are used to establish general guidelines for choosing 

an effective container size and charge size such that the use of R-513A in refrigerated transport units does 

not present risk to end-users or servicing technicians. These estimated charge and container sizes are fairly 

conservative as the analysis does not consider open container doors and other variables that would reduce 

the levels to which individuals would be exposed. The results of the threshold analyses are presented in 

Table 8b.

Table 8b. End-Use Exposure Threshold Analysis for HFO-1234yf Component

Refrigerated 

Transport 

Container

Scenario Charge Size 

(kg) Container Size (m3)

End-Use 

Exposure (ppm)

HFO-1234yf

Trucks Threshold Analysis 1a: Charge Size 1.1 78 (2,760 ft3)

1,500a Trailers Threshold Analysis 1b: Charge Size 1.4 100 (3,530 ft3)

Trucks Threshold Analysis 2a: Container Size 5 370 (13,010 ft3)

Trailers Threshold Analysis 2b: Container Size 15 1,120 (39,400 ft3)

Bold font indicates modeling results. a EPA-derived STEL (see Table 5).
Final—July 2, 2015

10

Based on these results, for a minimum container volume of 78 m3 (2,760 ft3), end-use exposure above the 

STEL would not be a concern as long as the charge size does not exceed 1.1 kg (see Threshold Analysis 1a 

in Table 8b) and for the maximum proposed charge sizes in trucks and trailers (i.e., 5 and 15 kg, 

respectively) exposure would not be a concern if the refrigeration unit is installed in a container of 

effective volume of at least 370 m3 (13,010 ft3

) and 1,120 m3 (39,400 ft3), respectively (see Threshold 

Analyses 2a and 2b in Table 8b). As shown in Table 8b, these recommended minimum container sizes 

vary in direct correlation with charge size, and are more conservative than the intended charge sizes 

provided by the submitter. However, these modeling results presented in Table 8a and 8b are derived using 

the STEL (i.e., 1,500 ppm), which is the most conservative short-term exposure limit for HFO-1234yf and 

reflect conditions that are assumed to be a worst-case scenario, as described in Section 5.

Infiltration rates through the opening of a refrigerated truck container have been measured to be 

approximately 2,520 m3

/hr, which is roughly 100 times the ventilation rates used in the threshold analyses 

(Bonjour et. al 2011). As previously discussed, EPA expects the refrigerated container doors to be open 

while personnel are present inside the container at end-use, increasing the air exchange rate inside of the 

unit and also encouraging any R-513A to flow towards the outside air. Therefore, under a reasonable 

worst-case scenario where the refrigerated container doors are open, the exposures shown in the modeling 

results (see Tables 8a and 8b) are unlikely.

Because refrigerated transport units using the proposed substitute were modeled using a conservative, 

worst-case scenario where the refrigerated transport container doors are closed, personnel exposure above 

the proposed substitute’s STEL is unlikely. However, these potential exceedances emphasize the 

importance associated with proper equipment use, employment of engineering controls to limit releases 

and/or exposures, and the need for workforce training. To prevent exposure and reduce the risk of acute 

toxicity hazards during larger releases in any location where an R-513A system is installed, EPA 

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

) and the ATEL for the 

individual components (i.e., 101,000 ppm for HFO-1234yf and 50,000 ppm for HFC-134a) are not 

exceeded and that proper leak protection devices are in place. In addition, EPA recommends the 

installation of refrigerant detection monitors on both ends of the refrigerated container, especially near the 

refrigeration system unit, and ensure the doors to the refrigerated container are open while personnel are 

inside. EPA also recommends that warning labels are present in the refrigerated transport container 

indicating that R-513A refrigerant is in use and can cause suffocation, injury, or death. An example of this 

warning label would read: “WARNING: R-513A gas can cause injury or death. Ventilate the area before 

entering. A high R-513A concentration can occur in this area and can cause suffocation.” Training 

materials and an operations manual describing procedures for proper use of the equipment, safety 

guidelines for handling R-513A, and safety training is required for all personnel operating and servicing 

the refrigerated transport unit. These procedures and guidelines should be acknowledged and followed to 

mitigate exposure in case of R-513A leakage in refrigerated transport units.

10. OCCUPATIONAL EXPOSURE ASSESSMENT

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

disposal of R-513A refrigerated transport equipment. To ensure that use of the proposed substitute in 

refrigerated transport does not pose an unacceptable risk to workers during charging, 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 

 6 ICF International maintains the Vintaging Model for EPA in order to simulate the aggregate impacts of the ODS phaseout on the
Final—July 2, 2015

11

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 to range between 0.6 percent and 8 percent of the equipment 

charge, respectively. 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 refrigerated transport units in trucks and trailers) (see Section 

10.2).

For equipment disposal of refrigerated truck and trailer systems, 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 ten units, 

only the last unit per workday would experience the catastrophic release (i.e., 100 percent). The remaining 

9 units were assumed to release only 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 STELs at charging and servicing and long-term 

exposure limits at disposal. Similar to the end-use exposure assessment, Tables 9 and 10 only present 

exposures for HFO-1234yf, the component with greater potential concerns. 

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

 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

12

Charging and servicing activities for refrigerated transport units 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 scenario and compared to their respective STELs (see Table 9). Because HFO-1234yf is present 

in larger concentrations and because it has a lower exposure limit than HFC-134a, Table 9 only presents 

exposures for HFO-1234yf, the component with greater potential concerns.

Table 9. Occupational Risk Assessment at Charging and Servicing for HFO-1234yf Componenta

Equipment Scenario Charge 

Size (kg) Component

15-minute TWA Occupational 

Exposure (ppm)

15-min Short 

Term 

Exposure 

Limits (ppm)

Charging 

(0.6% release)

Servicing 

(8% release)

Trucks Reasonable Worst-Case Scenario 1a 2

HFO-1234yf

6 75

1,500b Reasonable Worst-Case Scenario 1b 5 16 210

Trailers Reasonable Worst-Case Scenario 1c 7 22 300

Reasonable Worst-Case Scenario 1d 15 48 640

Bold font indicates modeling results. a Cells highlighted in green are the scenarios with acceptable exposure levels given various modeling assumption options. b EPA-derived STEL (see Table 5)

The anticipated 15-minute TWA exposures for the HFO-1234yf component of R-513A are not anticipated 

to exceed its STEL (i.e., 1,500 ppm) for all scenarios (see Table 9). 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 trained 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 or servicing of refrigerated transport units containing 

R-513A present a significant concern to workers.

10.3 Occupational Exposure at Disposal

Disposal of R-513A in refrigerated transport units is expected to occur with limited frequency 

(approximately ten disposal events per day) at disposal facilities 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, it was assumed that of the ten disposal events, nine 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 charge). Table 10 presents the 

maximum estimated 8-hour TWA occupational exposure levels for the constituents of R-513A during 

disposal. Because HFO-1234yf is present in larger concentrations and because it has a lower exposure 

limit than HFC-134a, Table 10 only presents the maximum estimated 8-hour TWA occupational exposure 

levels for HFO-1234yf, the component with greater potential concerns. 
Final—July 2, 2015

13

Table 10. Occupational Risk Assessment at Disposal for HFO-1234yf Componenta

Equipment Scenario

Maximum 

Charge Size 

(kg)

Component

8-hour TWA 

Occupational 

Exposure (ppm)

8-Hour Long 

Term Exposure 

Limits (ppm)

Trucks Reasonable Worst-Case Scenario 1a 2

HFO-1234yf

170

500b Reasonable Worst-Case Scenario 1b 5 420

Trailers Reasonable Worst-Case Scenario 1c 7 580

Reasonable Worst-Case Scenario 1d 15 1,250

Bold font indicates modeling results. a Cells highlighted in green are the scenarios with acceptable exposure levels given various modeling assumption options. b 8-hour WEEL

The results in Table 10 indicate that long-term (8-hour) worker exposure concentration of the HFO-1234yf

component of R-513A is not likely to exceed its WEEL (i.e., 500 ppm) in trucks; however, the reasonable 

worst-case disposal scenarios for trailer units of 7 and 15 kg charge size could potentially exceed the 

WEEL for HFO-1234yf. Although the modeling indicates that the worse-case disposal scenario could 

exceed the WEEL for HFO-1234yf, the estimated exposures were derived using conservative assumptions

(e.g., no mechanical or local exhaust ventilation). These types of systems are typically disposed of by 

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

efficiency and limit releases, and there are already established standards of practice and training 

requirements that apply to fluorinated refrigerants to reduce exposures (and would therefore extend to R513A 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 approximately ten percent 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 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 exceed the exposure limit for HFO-1234yf for some of 

the disposal release scenarios (i.e., Reasonable Worst-Case Scenarios 1c and 1d) for refrigerated transport 

applications, 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 R513A. 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-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, mechanical resistance gloves (e.g., oilrepellent or thermal resistance gloves) when handling cylinders and recovery equipment and chemicallyresistant gloves when handling the gas mixture (e.g., butyl rubber, chlorinated polyethylene, or neoprene). 

The installation of signage which warns room occupants to remain standing (as higher concentrations are 

likely to accumulate near the floor), 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 would further minimize toxicity risks. 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 refrigerated transport units.

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

14

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 refrigerated transport units. 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

15

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