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Significant New Alternatives Policy Program 

Refrigeration and Air Conditioning Sector 

Risk Screen on Substitutes in Refrigerated Transport 

Substitute: R-449A (Opteon® XP40) 

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-449A (also known as Opteon® XP40) 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-449A and Potential Impurities 

Constituent Chemical Formula CAS Number Concentration

(Weight Percent) 

Difluoromethane (HFC-32) CH2F2 75-10-5 ≤24.3%

1,1,1,2,2-Pentafluoroethane (HFC-125) CF3CHF2 354-33-6 ≤24.7%

2,3,3,3-Tetrafluoropropene (HFO-1234yf) CH2CFCF3 754-12-1 ≤25.3%

1,1,1,2-Tetrafluoroethane (HFC-134a) CF3CH2F 811-97-2 ≤25.7%

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 
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• Section 8: Asphyxiation Assessment 

• Section 9: End-Use Exposure Assessment 

• Section 10: Occupational Exposure Assessment 

• Section 11: General Population Exposure Assessment 

• Section 12: References 

2. SUMMARY OF RESULTS 

R-449A 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-449A 

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-449A 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-449A 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-449A. 

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-449A 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-449A in the refrigerated transport end-use, significant toxicity risk to 

consumers is also unlikely. 

Additional safeguards, including specified refrigerant concentration limits (RCL) of R-449A 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 R449A in refrigerated transport. The ozone depletion potential (ODP), global warming potential (GWP), and 

atmospheric lifetime (ALT) of the proposed substitute are presented in Error! Reference source not 

found.. 

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-449A 

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, R-404A, R-

 

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. 

3Ventilation 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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507A, and R-407C. Thus, EPA believes that the use of R-449A would result in substantially less harm to

the climate and ozone layer than the continued use of ODS and other commonly used refrigerants. 

Table 2. Atmospheric Impacts of R-449A 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-449A 0 1,397 NAc

Individual Components

HFC-32 0 675 4.9

HFC-125 0 3,500 29

HFC-134a 0 1,430 14

HFO-1234yf 0 4

d 11 daysd

CFC-12 0.82 10,900 100

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 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]). 

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-449A (i.e., HFC-32, HFC-125, 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-449A are not a concern. 

5. DISCUSSION OF END-USE SCENARIOS MODELED 

R-449A has been proposed for use in refrigerated transport units. As provided by the submitter, the typical 

and maximum charge sizes for R-449A in trucks and trailers are listed in Table 3. 

Table 3. Typical and Maximum Charge Sizes for Various R-449A 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-449A 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 
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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 

scenario; calculating the concentration of R-449A 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 doors closed. Although R-449A 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-449A 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 units, 

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

for different scenarios. R-449A is listed under safety group A1 with a RCL of 100,000 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 

 

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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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-449A, 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-449A, potential short-term, end-use exposures were evaluated 

on a component basis (i.e., HFC-32, HFC-125, HFC-134a and HFO-1234yf). Table 5 lists the relevant 

toxicity limits for R-449A 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-449A Components 

R-449A 

Component 

WGL

(Long-term Exposure) 

ppm 

EGL 

(Short-term Exposure) 

ppm 

Refrigerant Concentration 

Limit (RCL) 

ppm 

R-449A 830 (8-hour AEL) 2,490 (15-min STEL)a 100,000

Individual Components

HFC-32 1,000 (8-hour WEEL) 3,000 (15-min STEL)b 36,000

HFC-125 1,000 (8-hour WEEL) 3,000 (15-min STEL)c 75,000

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)d 101,000e

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-449A. A STEL for R-449A of 2,490 ppm was developed by EPA based on the 

830 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 = 830 ppm x 3 ≈ 2,490 ppm 

b Neither ACGIH nor AIHA recommend ceiling or short term exposure limits for HFC-32. A STEL for HFC-32 of 3,000 ppm was developed by 

EPA based on the 1,000 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 = 1,000 ppm x 3 ≈ 3,000 ppm.

c

 Neither ACGIH nor AIHA recommend ceiling or short term exposure limits for HFC-125. A STEL for HFC-125 of 3,000 ppm was developed by 

EPA based on the 1,000 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 = 1,000 ppm x 3 ≈ 3,000 ppm. 

d

 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 

e Although a RCL has not been proposed for HFO-1234yf, the recommended ATEL for HFO-1234yf is 101,000 ppm (DuPont Fluoroproducts 

2014). 
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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 

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 Average The 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. 
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According to the SDS, exposure to R-449A 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-449A

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-449A can cause symptoms such as light-headedness, dizziness, confusion, incoordination, 

drowsiness, unconsciousness, and anesthetic effects. Excessive inhalation of R-449A may also result in an 

irregular heartbeat or death, due to cardiac effects. 

If R-449A 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-449A to the skin may cause frostbite. In the case of dermal exposure, the SDS for 

R-449A 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-449A to the eyes could cause eye irritation. In case of ocular exposure, the 

SDS for R-449A 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-449A can be minimized by following the exposure guidelines, and ventilation 

and PPE recommendations outlined in the SDS for R-449A and this risk screen. 

7. FLAMMABILITY ASSESSMENT

R-449A 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 R449A 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-449A. 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

container 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. Additionally, 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 real-world 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% 
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Trailers Scenario 1b: Maximum Charge Size 15 100 (3,530 ft3) 20% 

Trucks Threshold Analysis 1a: Charge Size 120 78 (2,760 ft3) 

12% Trailers Threshold Analysis 1b: Charge Size 150 100 (3,530 ft3

) 

Trucks Threshold Analysis 2a: Container Size 5 3.3 (120 ft3) 

Trailers Threshold Analysis 2b: Container Size 15 9.8 (350 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-449A, 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. 

For the asphyxiation threshold analyses shown in Error! Reference source not found., 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-449A refrigerated truck unit would have to be at least 120 kg for asphyxiation to be a 

concern, which is twenty-four 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-449A refrigerated trailer unit in a 

100 m3 container would have to be at least 150 kg for asphyxiation to be a concern, which is ten 

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 3.3 m3

 (120 ft3), or approximately 

twenty-four 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 9.8 m3 (350 ft3

) or approximately 

ten 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 R449A 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-449A. 

9. END-USE EXPOSURE ASSESSMENT 

This section presents estimates of potential end-user exposures to R-449A 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-449A 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 

 

5

 Twelve percent oxygen in air is the NOAEL for hypoxia (ICF 1997). 
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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-449A 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-449A, which were then compared to the 

standard toxicity limits presented in Table 5 to assess the risk to end-users. Modeling results are presented 

in Table 8a. 

Table 8a. End-Use Exposure Assessment for R-449A Componentsa

Refrigerated 

Transport 

Containers 

R-449A 

Component 

Charge 

Size (kg) 

Container 

Size (m3) 

15-min TWA 

End-Use 

Exposure 

(ppm) 

15-minute Short 

Term Exposure 

Limitb 

(ppm) 

Refrigeration 

Concentration 

Limit (RCL)

Trucks 

HFC-32

2 78 

2,600 3,000 36,000

HFC-125 1,140 3,000 75,000

HFC-134a 1,400 8,000 50,000

HFO-1234yf 1,230 1,500c 101,000d

HFC-32

5 78 

6,500 3,000 36,000

HFC-125 2,860 3,000 75,000

HFC-134a 3,500 8,000 50,000 

HFO-1234yf 3,090 1,500c 101,000d

Trailers 

HFC-32

7 100 

7,190 3,000 36,000

HFC-125 3,170 3,000 75,000

HFC-134a 3,880 8,000 50,000

HFO-1234yf 3,410 1,500c 101,000d

HFC-32

15 100 

15,400 3,000 36,000

HFC-125 6,780 3,000 75,000

HFC-134a 8,300 8,000 50,000

HFO-1234yf 7,320 1,500c 101,000d

Bold font indicates modeling results. 

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

b See Table 5 for more information 

c

 EPA-derived STEL (see Table 5). 

d

 ATEL for HFO-1234yf is 101,000 ppm; see Table 5 for more information. 

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-449A were modeled. 

Although approximately half of the exposure estimates for the worst-case scenarios exceed the STEL for

R-449A components (i.e., 3,000 ppm for HFC-32 and HFC-125, 8,000 ppm for HFC-134a, and 1,500 ppm 

for HFO-1234yf) (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 one-time exposure can be 

more accurately evaluated by comparing the modeled exposure concentrations to the RCL and ATEL, 

which are limits intended to reduce the risks of acute toxicity hazards in normally occupied, enclosed
FINAL July 2, 2015

10 

spaces according to ASHRAE Standard 34 (see Table 6). All of the modeled exposure estimates are 

significantly lower than the RCL for HFC-32, HFC-125, and HFC-134a, (i.e., 36,000, 75,000, and 50,000 

ppm, respectively), as well as the ATEL for HFO-1234yf (i.e., 101,000 ppm).6

 Furthermore, the estimated 

exposures for R-449A in each of these scenarios are also significantly lower than the RCL for R-449A 

(i.e., 100,000 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 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 components of R449A. 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-449A 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 R-449A Components

Refrigerated 

Transport 

Container 

Scenario Charge Size 

(kg) Container Size (m3

) 

Trucks 

Threshold Analysis 1a: Charge Size 2.3 78 (2,760 ft3) 

Threshold Analysis 1b: Container Size 5 170 (6,140 ft3) 

Trailers 

Threshold Analysis 2a: Charge Size 2.9 100 (3,530 ft3)

Threshold Analysis 2b: Container Size 15 530 (18,700 ft3) 

Bold font indicates modeling results. 

a

 EPA-derived STEL (see Table 5).

Based on these results, for a minimum container volume of 78 m3 (2,760 ft3), end-use exposure would not 

exceed the STEL of any components of R-449A as long as the charge size does not exceed 2.3 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 170 m3 (6,140 ft3) and 530 m3 (18,700 ft3), respectively (see 

Threshold Analyses 1b 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, the modeling results presented in Table 8a and 8b are

derived using the STELs for R-449A components (i.e., 3,000 ppm for HFC-32 and HFC-125, 8,000 ppm 

for HFC-134a, and 1,500 ppm for HFO-1234yf) and reflects 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-449A 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 

 

6 Although a RCL has not been proposed for HFO-1234yf, the recommended ATEL for HFO-1234yf is 101,000 ppm (DuPont 

Fluoroproducts 2014). The ATEL is a refrigerant concentration limit intended to reduce the risks of acute toxicity hazards in 

normally occupied, enclosed spaces according to ASHRAE Standard 34.
FINAL July 2, 2015

11 

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-449A system is installed, EPA 

recommends that the proposed RCL for R-449A (i.e., 100,000 ppm or 370 g/m3

) and the RCL for the 

individual components (or ATEL for HFO-1234yf) 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-449A refrigerant is in use and can cause suffocation, injury, or death. An example of this warning label 

would read: “WARNING: R-449A gas can cause injury or death. Ventilate the area before entering. A 

high R-449A 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-449A, 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-449A 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-449A 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.7 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 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 

 

7

 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

12 

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 for both scenarios were compared to STELs at charging and 

servicing in Table 9 and long-term exposure limits at disposal in Table 10. 
FINAL July 2, 2015

13 

10.1 Occupational Exposure at Manufacture 

During manufacture of the components and blending of R-449A, the SDS for each component (i.e., HFC32, HFC-125, HFC-134a and HFO-1234yf) 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 the components of R-449A 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-449A and its 

components, there is no significant risk to workers during the manufacture of R-449A. 

10.2 Occupational Exposure at Charging and Servicing 

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-449A 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-449A constituent were estimated for the charging and servicing 

exposure scenario and compared to their respective STELs (see Table 9). 

Table 9. Occupational Risk Assessment at Charging and Servicing for R-449A Componentsa

Refrigerated 

Transport 

Containers 

R-449A 

Component 

Charge 

Size (kg) 

15-min TWA Occupational 

Exposure (ppm) 

15-minute Short 

Term Exposure 

Limitb 

(ppm) 

Refrigeration 

Concentration 

Limit (RCL) Charging b

(0.6% release) 

Servicing 

(8% release) 

Trucks 

HFC-32

2 

6.0 81 3,000 36,000

HFC-125 2.7 36 3,000 75,000

HFC-134a 3.3 44 8,000 50,000

HFO-1234yf 2.9 38 1,500c 101,000d

HFC-32

5 

15 200 3,000 36,000

HFC-125 6.7 89 3,000 75,000

HFC-134a 8.2 110 8,000 50,000

HFO-1234yf 7.2 96 1,500c 101,000d

Trailers 

HFC-32

7 

21 280 3,000 36,000

HFC-125 9.4 130 3,000 75,000

HFC-134a 11 150 8,000 50,000

HFO-1234yf 10 140 1,500c 101,000d

HFC-32

15 

46 610 3,000 36,000

HFC-125 20 270 3,000 75,000

HFC-134a 25 330 8,000 50,000
FINAL July 2, 2015

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HFO-1234yf 22 290 1,500c 101,000d

Bold font indicates modeling results. 

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

b

 See Table 5 for more information. 

c

 EPA-derived STEL (see Table 5). 

d

 ATEL for HFO-1234yf is 101,000 ppm; see Table 5 for more information. 

The anticipated 15-minute TWA exposures for the components of R-449A are not anticipated to exceed 

their respective STELs (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-449A present a significant 

concern to workers. 

10.3 Occupational Exposure at Disposal 

Disposal of R-449A 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-449A during 

disposal. 

Table 10. Occupational Risk Assessment at Disposal for R-449A Componentsa

Refrigerated 

Transport 

Containers 

R-449A 

Component 

Charge 

Size (kg) 

8-hour TWA 

Occupational 

Exposure (ppm) 

8-hour Long 

Term Exposure 

Limits (ppm)b

Refrigeration 

Concentration 

Limit (RCL) 

Trucks 

HFC-32

2 

160 1,000 36,000

HFC-125 70 1,000 75,000

HFC-134a 85 1,000 50,000

HFO-1234yf 75 500 101,000c

HFC-32

5 

400 1,000 36,000

HFC-125 170 1,000 75,000 

HFC-134a 210 1,000 50,000

HFO-1234yf 190 500 101,000c

Trailers 

HFC-32

7 

560 1,000 36,000

HFC-125 240 1,000 75,000

HFC-134a 300 1,000 50,000

HFO-1234yf 260 500 101,000c

HFC-32 15 1,190 1,000 36,000

HFC-125 520 1,000 75,000 
FINAL July 2, 2015

15 

HFC-134a 640 1,000 50,000

HFO-1234yf 560 500 101,000c

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 

c

 ATEL for HFO-1234yf is 101,000 ppm; see Table 5 for more information. 

The results in Table 10 indicate that long-term (8-hour) worker exposure concentration during disposal is 

not likely to exceed the WEEL for components of R-449A in trucks and trailers with the exception of 

HFC-32 and HFO-1234yf in the maximum proposed charge size in trailers (i.e., 15 kg). Although the 

modeling indicates that the worst-case disposal scenario for the maximum proposed charge size in trailers 

could exceed the WEEL for HFC-32, the estimated exposures were derived using conservative 

assumptions (e.g., no mechanical or local exhaust ventilation), and represent a worst-case scenario with a 

low probability of occurrence. 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 R-449A 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 components of R-449A in

one of the disposal release scenarios (i.e., trailer units of 15 kg charge size), the recommendations for 

proper engineering controls and PPE in the SDS for R-449A should be followed. Adequate ventilation 

should always be established during any use, handling, or storage of R-449A. If recovery and disposal is 

taking place in an enclosed space without any mechanical ventilation, facilities should be cleared of nonessential 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-449A to prevent dispersion throughout the workplace. In addition, an eye wash and safety shower 

should be near the manufacturing facility and locations where R-449A 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-449A, there is no significant risk to workers during the 

manufacturing, installation, servicing, and disposal of R-449A in refrigerated transport units. 

11. GENERAL POPULATION EXPOSURE ASSESSMENT 

R-449A 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-449A is a gas and, therefore, releases to ground or surface 

water are not anticipated, as R-449A is anticipated to dissipate into the atmosphere upon release to outside 
FINAL July 2, 2015

16 

air (i.e., because natural ventilation rates would be higher and there is no enclosed space to maintain a high 

concentration of R-449A). Should air releases during manufacturing operations occur, engineering controls 

should be used (e.g., carbon absorption scrubbers) to collect R-449A and prevent the release of R-449A 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-449A is not expected to pose a significant toxicity risk to the general population. 
FINAL July 2, 2015

17 

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