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Significant New Alternatives Policy Program 

Refrigeration and Air Conditioning Sector 

Risk Screen on Substitutes in Retail Food Refrigeration and Commercial Ice 

Machines 

Substitute: R-448A 

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-448A as a substitute in the retail food refrigeration (specifically, 

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

and commercial ice machines end-uses. Table 1 presents the composition of the proposed substitute. 

Table 1. Composition of R-448A and Potential Impurities 

Constituent Chemical Formula CAS Number Concentration

(Weight Percent)a

Difluoromethane (HFC-32) CH2F2 75-10-5 ≤26% 

Pentafluoromethane (HFC-125) C2HF5 354-33-6 ≤26% 

1,1,1,2-Tetrafluoroethane (HFC134a) CF3CH2F 811-97-2 ≤21% 

2,3,3,3-Tetrafluoro-prop-1-ene 

(HFO-1234yf) C3H2F4 754-12-1 ≤20% 

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

(HFO-1234ze(E)) CHFCHCF3 29118-24-9 ≤7% 

Potential Impurities (Maximum Concentration) 
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Constituent Chemical Formula CAS Number Concentration

(Weight Percent)a

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

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

• Section 3: Atmospheric Assessment 

• Section 4: Volatile Organic Compound Assessment 

• Section 5: Discussion of End-Use Scenario Modeled 

• Section 6: Potential Health Effects 

• Section 7: Flammability Assessment 

• Section 8: Asphyxiation Assessment 

• Section 9: End-Use Exposure Assessment 

• Section 10: Occupational Exposure Assessment 

• Section 11: General Population Exposure Assessment 

• Section 12: References 

2. SUMMARY OF RESULTS 

R-448A is recommended for SNAP approval for the retail food refrigeration and commercial ice machine 

end-uses. EPA's risk screen indicates that the use of the proposed substitute will be less harmful to the 

atmosphere than the continued use of 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-448A 

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-448A is 

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

It is expected that the safety data sheet (SDS) for R-448A and good manufacturing practices will be 

adhered to. 

Additionally, it is expected that the appropriate safety and personal protective equipment (PPE) (e.g., 

protective gloves, tightly sealed goggles, protective work clothing, and suitable respiratory protection in 

case of leakage or insufficient ventilation) consistent with Occupational Safety and Health Administration 

(OSHA) guidelines will be used during manufacture, installation and servicing, and disposal of retail food 

refrigeration systems and commercial ice machines using R-448A. Because retail food refrigeration 

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

ventilation in accordance with EPA recommendations and the equipment maintenance manuals for R448A in each end-use, significant toxicity risk to consumers is also unlikely. 
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Additional safeguards, including specified refrigerant concentration limits (RCL) of R-448A 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 R448A in retail food refrigeration and commercial ice machines. The ozone depletion potential (ODP), 

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

in 

 

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

prescribes safety requirements. 

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

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

toxicity and flammability data are included. 

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

intended to provide indoor air quality that is acceptable to human occupants and that minimizes adverse health effects. 
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Table 2. 

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

shorter ALT when compared to refrigerants currently used in these end uses such as CFC-12, R-502, and 

HCFC-22. In addition, R-448A 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 

commercial refrigeration, such as HFC-134a, R-404A, R-507A, and R-407C. Thus, EPA believes that the 

use of R-448A would result in substantially less harm to the climate and ozone layer than the continued 

use of ODS and other commonly used refrigerants. 
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Table 2. Atmospheric Impacts of R-448A Components Compared to Other Refrigerants Used in 

Retail Food Refrigeration and Commercial Ice Machines 

Refrigerant Ozone Depleting Potential

(ODP)a

Global Warming Potential

 (GWP)b

Atmospheric Lifetime in 

Years (ALT)b 

R-448A 0 1,387 NAc

Individual Components

HFC-32 0 675 4.9b

HFC-125 0 3,500 29b

HFC-134a 0 1,430 14b

HFO-1234yf 0 4

d 11 daysd

HFO-1234ze(E) 0 1

e 16.4 dayse

CFC-12 0.82 10,900 100

R-502f 0.2 4,650 NAg

HCFC-22 0.13 1,810 12a

R-404Ah 0 3,922 NAi

R-507Aj 0 3,985 NAk

R-407Cl 0 1,774 NAm

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 Hodnebrog, O. et al. (2013) 

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

g

 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]). 

h

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

i

 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]). 

j

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

k

 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]).

l

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

m 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-448A (i.e., HFC-32, HFC-125, HFC-134a, HFO-1234yf, and HFO-1234ze(E)) are 

exempt from the definition of VOCs under CAA regulations (40 CFR 51.100(s)). Therefore, VOC impacts 

from the release of R-448A are not a concern. 

5. DISCUSSION OF END-USE SCENARIOS MODELED 

The submission states that R-448A retail food refrigeration equipment will contain typical charge sizes 

ranging from 0.9 kg for a typical stand-alone, self-contained display case to a maximum charge size of 300 

kg for a direct rack system. Commercial ice machines are anticipated to have a typical charge size of 8 kg 

and a maximum charge size of 20 kg. The intended maximum and typical charge sizes for all of the 

proposed applications are listed in Table 3. 
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Table 3. Typical and Maximum Charge Sizes for Various R-448A End-Uses and Applications 

End-Use Application Typical Charge Size 

(kg) 

Maximum Charge Size 

(kg) 

Retail food 

refrigeration 

Convenience Store 30 60 

Direct rack / 4 compressor 300 400 

Indirect rack / 4 compressor 150 250 

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

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

Stand-alone self-contained display case

(charge size is per door) 0.9 1.2 

Commercial ice 

machines Packaged and split 8 20 

Bolded applications and charge sizes represent those modeled in this risk screen. 

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

catastrophic leak of refrigerant occurs at the end-use for the following applications: direct rack system (i.e., 

grocery supermarket), stand-alone beverage cooler (i.e., convenience store), or commercial ice machine

(i.e., seafood processing facility). The analysis considers the maximum charge size provided by the 

submitter for each scenario. Because retail refrigeration equipment can be installed in a wide range of 

locations with varying room volumes, the analysis in this risk screen conservatively assumes that the direct 

rack system is located in a grocery supermarket, the beverage cooler is located in a convenience store, and 

the commercial ice machine is located in a seafood processing facility.4

 

The grocery supermarket is assumed to have an effective volume of 24,200 m3

 (855,000 ft3) with an 

effective floor area of 4,400 m2 (i.e., excluding the space filled by the rack system, shelving, display cases, 

etc.) and a height of 5.5 meters (Armines 2008). Based on a minimum convenience store sizes located in

California (Armines 2008), the convenience store is assumed to have an effective volume of 244 m3

 (8,620 

ft3

) with an effective floor area of 100 m2 (i.e., excluding the space filled by the beverage cooler, shelving, 

display cases, etc.) and a height of 2.44 meters. 

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

processing facility with an assumed effective volume of 5,700 m3 (201,300 ft3), with an effective floor area 

of 1,040 m2 (i.e., excluding the space filled by the ice machine, shelving, processing equipment, etc.) and a 

height of 5.5 meters. 

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

supermarket, convenience store, or seafood processing facility with 8, 1, and 15 air changes per hour 

(ACH), 5,6 respectively over the course of two time durations: 1) one minute, which represents a 

catastrophic release of refrigerant due to a puncture or other major damage to the refrigeration system, and 

2) fifteen minutes, which represents the accidental release of refrigerant due to a non-catastrophic leak in 

the system (e.g., valve failure). The one-minute time duration is most appropriate for flammable 

refrigerants and presents a less relevant scenario for R-448A, which is nonflammable. Therefore, while

both scenarios are evaluated in this risk screen for consistency purposes, the scenario which analyzes a 

release of refrigerant over a 15-minute time duration more accurately represents a reasonable worst-case 

scenario for R-448A in retail food refrigeration and commercial ice machines. 

 

4 A seafood processing facility is assumed to appropriately represent the use of commercial ice machines in any large industrial 

facility and recognizes that a commercial ice machine with a large production capacity can be installed in a wide variety of 

industrial locations.

5 The air exchange rates for a grocery supermarket and convenience store are derived from the requirements in ANSI/ASHRAE 

Standard 62.1-2007, Table 6.1 (ANSI/ASHRAE 2007). Ventilation requirements (presented as cubic feet per minute per square 

foot of ventilated space in the standard) were converted to air exchanges per hour using the assumed room size for the scenario.

6

 The air exchange rates for a seafood processing facility are derived from the suggested sufficient air changes per hour in enclosed 

processing and food handling areas of between 5 and 25 air changes per hour (Lelieveld, H.L.M. 2014). 
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A vertical concentration gradient is also assumed since R-448A is denser than air (the specific gravities of 

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

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

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

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

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

Table 4. End-Use Scenario Model Assumptions 

Parameter Assumptions 

Large Retail Food Small Retail Food Ice Machine

Refrigeration Unit Direct Rack System Stand-Alone Beverage 

Cooler Commercial Ice Machine 

Room Grocery Supermarket Convenience Store Seafood Processing 

Facility 

Charge Size (kg) 400 1.2 20 

Length of Release (minutes) 1; 15 1; 15 1; 15 

Room Size (volume - m3) 24,200a 244b 5,700c

Room Ventilation (air changes per hour) 8 1 15

Vertical Concentration Gradient Yes Yes Yes

a The average grocery supermarket sales area size found during a California survey (Armines 2008) – 4,400 m2

 – was used for this scenario and 

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

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

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

100 m2 (1,076 ft2) – was used for this scenario and a 2.44-meter (8 ft) ceiling was assumed. 

c

 The average size of the seafood processing facility is assumed to be consistent with typical factory size used in occupational exposure 

modeling. 

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

commercial ice machines may be placed in a variety of locations, including retail stores, manufacturing 

establishments, and other spaces with differing sizes and ventilation rates. When units are installed in 

smaller, enclosed spaces, there is a higher risk for asphyxiation or exposure concerns. To address this 

variability in room volumes and charge sizes for installed retail food equipment and commercial ice 

machines, this risk screen incorporates threshold analyses in addition to the worst-case scenario modeling. 

The threshold analyses are performed in order to determine the room size and charge size requirements 

that ensure that the use of R-448A in retail food refrigeration and commercial ice machines does not 

present risk to end-users or servicing technicians.

6. POTENTIAL HEALTH EFFECTS 

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

commercial ice machines, EPA identified the relevant toxicity threshold values for comparison to modeled 

exposure concentrations for different scenarios. According to ASHRAE Standard 34-2013, R-448A is 

listed under safety group A1 with a RCL of 110,000 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-448A in addition to the lower flammability limit, 

hypoxia no observed adverse effect level (NOAEL), and exposure limits, as an additional, conservative 

limit to ensure that significant asphyxiation, toxicity risks, and end-use exposure risks, respectively, do not 

occur. 
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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-448A, potential short-term, end-use exposures were evaluated 

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

lists the relevant toxicity limits for R-448A 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-448A Components 

R-448A 

Component 

WGL

(Long-term Exposure) 

ppm 

EGL 

(Short-term Exposure) 

ppm 

Refrigerant Concentration 

Limit (RCL) 

ppm 

R-448A 890 (8-hour AEL) 2,670 (15-min STEL)a 110,000 

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 NAe

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

NA = Not available 

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-448A. A STEL for R-448A of 2,670 ppm was developed by EPA based on the 

890 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 = 890 ppm x 3 ≈ 2,670 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 (Honeywell 2014a). 

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

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

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

g Although a RCL has not been proposed for HFO-1234ze(E), the recommended ATEL for HFO-1234ze(E) is 59,000 ppm (Honeywell 2014a). 
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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-448A may be hazardous if inhalation, skin contact, or eye contact 

with occurs. The most likely pathway of exposure is through inhalation. R-448A 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 R-448A 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. Rescuers should not attempt to retrieve victims of exposure to R-448A without adequate PPE. At a 

minimum, a self-contained breathing apparatus (SCBA) should be worn. Exposures of R-448A to the skin 

may cause frostbite. In the case of dermal exposure, the SDS for R-448A 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-448A to the eyes

could cause eye irritation. In case of ocular exposure, the SDS for R-448A 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-448A can be minimized by following the exposure guidelines and ventilation 

and PPE recommendations outlined in the SDS for R-448A and this risk screen. 

7. FLAMMABILITY ASSESSMENT 

R-448A is classified as an A1 refrigerant by ASHRAE 34, and is considered to be nonflammable 

(Honeywell 2014a, ASHRAE 2015). Based on this classification, manufacture, servicing, and use of R448A is not expected to present a flammability risk in industrial process air conditioning. 

8. ASPHYXIATION ASSESSMENT 

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

R-448A. In this section, risk of asphyxiation is assessed in three ways: 1) modeling the oxygen 

concentration under the charge size and room size specified in the worst-case scenario, 2) performing a 

threshold analysis of minimum charge size at which an asphyxiation risk could occur in the room size 

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

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

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

smaller than this are expected to cause an asphyxiation risk). This analysis does not consider ventilation or 

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

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

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

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

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

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

assessment are summarized in Table 7. 
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Table 7. Asphyxiation Assessmenta,b

Equipment Scenario Charge 

Size (kg) 

Effective Room 

Size (m3) 

Percent Oxygen 

Concentration in 

Lower 0.4 Meters 

Direct Rack System Reasonable Worst-Case 1 400 24,200 (855,000 ft3) 20% 

Beverage Cooler Reasonable Worst-Case 2 1.2 244 (8,620 ft3) 21%

Ice Machine Reasonable Worst-Case 4 20 5,700 (201,300 ft3) 21% 

Direct Rack System Threshold Analysis 1a: Charge Size 3,000 24,200 (855,000 ft3

) 12%

Threshold Analysis 1b: Room Size 400 3,230 (114,000 ft3) 12%

Beverage Cooler Threshold Analysis 2a: Charge Size 70 244 (8,620 ft3

) 12%

Threshold Analysis 2b: Room Size 1.2 4 (141 ft3) 12%

Ice Machine Threshold Analysis 3a: Charge Size 710 5,700 (201,300 ft3

) 12% 

Threshold Analysis 3b: Room Size 20 160 (5,690 ft3) 12% 

Bold font indicates modeling results. 

a

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

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

b

 The typical concentration of oxygen in air is considered to be 21 percent (Mackenzie & Mackenzie 1995). 

Based on the worst-case scenario modeling assumptions, R-448A in retail food refrigeration and 

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

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

room must be reduced to 12 percent.7

 Based on the reasonable worst-case scenario modeling assumptions, 

use of R-448A in retail food refrigeration equipment and commercial ice machines does not present a 

significant risk of asphyxiation: 

• As shown in Threshold Analysis 1a for direct rack systems, the minimum charge size of R-448A 

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

volume 24,200 m3

 (855,000 ft3) was calculated to be 3,000 kg assuming that 1) nitrogen and 

oxygen retain the same relative volumes in the rooms with the balance composed entirely of R448A, and 2) the pressure of the room does not increase significantly with the addition of the 

refrigerant. This amount represents ten times the typical charge of approximately 300 kg (or more 

than seven times the maximum charge size of 400 kg) for a direct rack R-448A system. 

• Under Threshold Analysis 2a for beverage coolers, the minimum charge of R-448A necessary to 

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

(8,620 ft3) was calculated to be approximately 70 kg, which represents approximately 78 times the 

typical charge of 0.9 kg for a single R-448A beverage cooler (or more than 58 times the maximum 

intended charge size of 1.2 kg). 

• For commercial ice machines, Threshold Analysis 3a shows that the minimum charge of R-448A 

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

5,700 m3

 (201,300 ft3) was calculated to be approximately 710 kg, more than 88 times the typical 

charge of approximately 8 kg for a commercial ice machine (or more than 35 times the maximum 

charge size of 20 kg). 

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

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

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

 

5

 Twelve percent oxygen in air is the No Observed Adverse Effect Level (NOAEL) for hypoxia (ICF 1997).
FINAL July 2, 2015

12 

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

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

equipment charge sizes provided by the submitter were also determined: 

• For direct rack systems, in order for asphyxiation to be of concern with the maximum charge size 

of 400 kg, the system would have to be installed in a store with an effective volume of 3,230 m3

(114,000 ft3) (see Threshold Analysis 1b in Table 7). 

• For beverage coolers, in order for asphyxiation to be of concern with the maximum charge size of 

1.2 kg, the volume of the food preparation area would have to be about 4 m3

 (141 ft3) (see 

Threshold Analysis 2b in Table 7). 

• For commercial ice machines, Threshold Analysis 3b indicates that the volume of the commercial 

ice machine area would have to be about 160 m3

 (5,690 ft3) with the maximum charge size of 20 

kg in order for asphyxiation to be of concern. 

Based on the worst-case modeling results and threshold analysis, EPA does not believe that the use of R448A in retail food refrigeration and commercial ice machines poses a significant risk of asphyxiation or 

impaired coordination to personnel, provided systems are installed in appropriate spaces according to 

guidelines from the manufacturer and the SDS for R-448A. 

9. END-USE EXPOSURE ASSESSMENT 

This section presents estimates of potential end-user exposures to R-448A and each of its chemical 

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

refrigeration and commercial ice machines. An end-use exposure analysis was performed to examine 

potential catastrophic releases of R-448A under the reasonable worst-case scenarios outlined in Section 5. 

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

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

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

from catastrophic leakage of refrigerant from retail food refrigeration and commercial ice machines were 

examined. As discussed in Section 5, the full charge of the unit is assumed to be emitted over the course of 

1 minute and 15 minutes, where the latter scenario more accurately represents a reasonable worst-case 

scenario for R-448A in retail food refrigeration and commercial ice machines because R-448A is 

nonflammable. The analysis was undertaken to determine the 15-minute exposures for R-448A, which 

were then compared to the standard toxicity limits presented in Table 5 to assess the risk to end-users. The 

estimated TWA values are fairly conservative as the analysis does not consider opened windows, fans 

operating, conditioned airflow (either heated or cooled) and other variables that would reduce the levels to 

which individuals would be exposed. 
FINAL July 2, 2015

13 

Table 8. End-Use Exposure Assessment for R-448A Componentsa

Equipment R-448A 

Component 

Charge 

Size 

(kg) 

Room 

Size 

(m3) 

15-minute TWA Occupational 

Exposure (ppm) 15-min Short 

Term Exposure 

Limits (ppm) 

Refrigerant 

Concentration 

Limit (RCL) 

ppm 

1-minute 

release 

15-minute 

release 

Direct Rack 

System 

HFC-32

400 24,400

13,900 9,110 3,000 36,000

HFC-125 6,020 3,950 3,000 75,000

HFC-134a 5,720 3,800 8,000 50,000

HFO-1234yf 4,900 3,200 1,500 101,000b

HFO-1234ze(E) 1,710 1,120 2,400 59,000c

Beverage 

Cooler 

HFC-32

1.2 244

3,140 1,700 3,000 36,000

HFC-125 1,360 750 3,000 75,000

HFC-134a 1,293 710 8,000 50,000

HFO-1234yf 1,100 610 1,500 101,000b

HFO-1234ze(E) 390 210 2,400 59,000c 

Ice 

Machine 

HFC-32

20 5,700 

1,910 1,430 3,000 36,000

HFC-125 826 622 3,000 75,000

HFC-134a 785 591 8,000 50,000

HFO-1234yf 669 503 1,500 101,000b

HFO-1234ze(E) 234 176 2,400 59,000c 

Bold font indicates modeling results. 

a

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

b

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

c

 ATEL for HFO-1234ze(E) is 59,000 ppm; see Table 5 for more information. 

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

and ice machines, catastrophic releases of the maximum charge sizes of R-448A were modeled. The 

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

anticipated 15-minute TWA exposures are likely to exceed the respective STELs for the HFC-32, HFC125, and HFO-1234yf components of R-448A in direct rack systems assuming both 1-minute and 15-

minute release scenarios, as well as for the HFC-32 component of R-448A in beverage coolers assuming a

1-minute refrigerant release (see Table 8). 

Although the exposure estimates for the reasonable worst-case scenario for a direct rack system exceed the 

respective STELs for the HFC-32, HFC-125, and HFO-1234yf components of R-448A and the HFC-32 

component of R-448A for beverage coolers (see Table 8), the STEL is a conservatively-derived exposure 

limit that is intended to protect workers in an occupational setting in which they are exposed to these 

chemicals on a daily basis. The STEL values do not represent limits for a single exposure in a lifetime. 

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

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

evaluated by comparing the modeled exposure concentrations to the refrigerant concentration limit (RCL) 

or acute toxicity exposure limit (ATEL) for each respective component, which are limits intended to 

reduce the risks of acute toxicity hazards in normally occupied, enclosed spaces according to ASHRAE 

Standard 34 (see Table 6). All of these exposure estimates are significantly lower than the RCL or ATEL 

for each component. Furthermore, the estimated exposures for R-448A in each of these scenarios are also 

significantly lower than the RCL for R-448A (i.e., 110,000 ppm). 

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

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

the actual room attributes where R-448A retail food refrigeration equipment and commercial ice machines 

will be installed. Finally, these exposures represent concentrations of leaked refrigerant in the bottom 0.4 

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

of the room. The probability that an individual would be present in this lower compartment (e.g., prone or 
FINAL July 2, 2015

14 

supine on the floor) in the event of the catastrophic release of refrigerant is low. Furthermore, although 

children may be at increased risk because of their short stature when the proposed substitute is found at 

higher concentrations in the lower compartment of the room, the probability that they are present in the 

location in which a catastrophic release of the entire charge of the commercial refrigeration system is low. 

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

proposed RCL for R-448A (i.e., 110,000 ppm or 390 g/m3

) is not exceeded in any location where an R448A system is installed, unless proper leak protection devices are in place in order to prevent exposures 

of R-448A beyond the recommended limits. Proper leak protection devices, engineering control 

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

those described in Table 8. 

10. OCCUPATIONAL EXPOSURE ASSESSMENT 

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

disposal of R-448A retail food refrigeration equipment and commercial ice machines. To ensure that use of 

the proposed substitute in retail food refrigeration and commercial ice machines does not pose an 

unacceptable risk to workers during servicing and disposal, occupational exposure modeling was 

performed using a box-model approach. For a detailed description of the methodology used for this 

screening assessment, the reader is referred to the occupational exposure and hazard analysis described in 

Chapter 5 of the Background Document. 

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

Model.8 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 per event was 

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

the retail food refrigeration end-uses, the release per event was conservatively assumed to range between 

0.25 percent and 5 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., 8 units divided by 8 hours per workday for beverage coolers and commercial ice 

machines and one unit divided by 8 hours per workday for direct rack systems) (see Section 10.2). 

For disposal of direct rack systems, it was conservatively assumed that one unit is disposed of during an 8-

hour work day. For beverage coolers and commercial ice machines, the release per event was 

conservatively assumed to be 100 percent of the equipment charge (representing a catastrophic release). It 

was assumed that 10 units are disposed of during an 8-hour work day; however it was assumed that of the 

10 units, only the last unit per work day would experience the catastrophic release (i.e., 100 percent of the 

equipment charge). The remaining 9 units were assumed to release an incidental amount of refrigerant 

(i.e., 1 percent per unit) from the connecting and disconnecting of lines, as it is likely that if a worker was 

exposed to the entire charge of a system during disposal activities, they would immediately stop working, 

clear the area until all refrigerant has been removed from the space (e.g., through ventilation), and adhere 

to the exposure procedures recommended in the SDS for the proposed substitute (see Section 10.3). 

The modeled exposure concentrations were compared to STELs at installation and servicing and long-term

exposure limits at disposal. 

 

8

 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

15 

10.1 Occupational Exposure at Manufacture 

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

the United States. During manufacture of the components and blending of R-448A, the SDS for each 

component (i.e., HFC-32, HFC-125, HFC-134a, HFO-1234yf, and HFO-1234ze(E)) should be referenced 

and proper engineering controls and PPE used. 

R-448A and its components are not expected to pose a risk to workers during manufacture or blending 

when the engineering controls and PPE recommendations referenced in the SDS for R-448A and all of its 

components are followed. Release points and exposure during refrigerant blending operations would 

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

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

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

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

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

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

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

protective gloves (OSHA 1994). 

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

such as hydrogen fluoride and hydrogen chloride if HFC-32, HFC-125, HFC-134a, HFO-1234f, or HFO1234ze(E) are exposed to high temperatures or fire. Other reaction products such as carbon dioxide might 

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

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

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

are followed in accordance with both good industrial hygiene and manufacturing practices and the SDS for 

R-448A and its components, there is no significant risk to workers during the manufacture of R-448A. 

10.2 Occupational Exposure at Charging and Servicing 

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

typically field-erected and therefore, equipment is charged in the field. Charging for smaller retail 

refrigeration equipment (e.g., beverage coolers and commercial ice machines) would be conducted by the

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

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

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

and recovery equipment. 

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

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

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

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

fittings should result in de minimus releases (Honeywell 2014a). 

During servicing, used refrigerant from R-448A retail food refrigeration equipment and commercial ice 

machines is pumped into a canister, where it is stored until it is recycled (i.e., filtered and reused). During 

the transfer to the initial canister, incidental refrigerant releases may occur during connection and 

disconnection of the recharging hose fittings (Honeywell 2014a). Isolation and evacuation of lines or 

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

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

and alarms also help minimize exposure. 

Charging and servicing activities for retail refrigeration equipment and commercial ice machines are not 

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

in the R-448A SDS and maintenance manual, undergo proper training, and wear appropriate PPE (e.g., 
FINAL July 2, 2015

16 

gloves and safety glasses). Nevertheless, the potential occupational exposure during servicing was 

analyzed. The maximum 15-minute TWA exposures for each R-448A constituent were estimated for the 

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

Table 9. Occupational Risk Assessment at Charging and Servicing for R-448A Componentsa 

Equipment R-448A 

Component 

Charging Servicing 15-min Short Term 

Exposure Limits 

(ppm)c

Release 

Rateb

15-minute 

TWA (ppm) 

Release 

Rateb

15-minute 

TWA (ppm) 

Direct Rack Systemd

HFC-32

2% 

1,140

5% 

2,860 3,000

HFC-125 495 1,240 3,000

HFC-134a 470 1,180 8,000

HFO-1234yf 401 1,000 1,500

HFO-1234ze(E) 140 91 2,400

Beverage Cooler 

HFC-32

1% 

13.0

0.25% 

13.7 3,000

HFC-125 5.63 5.92 3,000

HFC-134a 5.35 5.56 8,000

HFO-1234yf 4.56 4.79 1,500

HFO-1234ze(E) 1.60 0.44 2,400

Ice Machine 

HFC-32

1% 

217

3% 

2,730 3,000

HFC-125 93.9 1,180 3,000

HFC-134a 89.2 1,120 8,000

HFO-1234yf 76.0 958 1,500

HFO-1234ze(E) 26.6 87.2 2,400

Bold font indicates modeling results. 

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

b

 Release rates are consistent with IPCC (2006), CARB (2013), and EPA’s Vintaging Model. 

c

 See Table 4 for more information

d

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

The 15-minute STEL for all components of R-448A is not exceeded in the charging or servicing exposure 

scenarios for all three equipment types. These estimated exposures were derived using conservative 

assumptions and do not take into account the use of ventilation or PPE, and all of these exposure estimates 

are significantly lower than the RCL or ATEL for each component, which are limits intended to reduce the 

risks of acute toxicity hazards in normally occupied, enclosed spaces according to ASHRAE Standard 34.

Furthermore, these types of systems are typically serviced by Section 608-certified personnel using proper 

industrial hygiene techniques and using proper engineering controls (e.g., local ventilation, refrigerant 

detectors, and alarm systems). Thus, EPA does not believe that charging, installation, or servicing of retail 

food refrigeration units and commercial ice machines containing R-448A presents a significant concern to 

workers. 

10.3 Occupational Exposure at Disposal 

Disposal of R-448A retail food refrigeration equipment is expected to occur with limited frequency (up to 

approximately ten disposal events per day for smaller equipment such as beverage coolers and commercial 

ice machines and one disposal event per day for direct rack systems) at disposal facilities or, for larger 

equipment (e.g., direct rack systems) at the end-use and with limited duration of exposure to the installed 

refrigerant. Typically, potential exposures to the refrigerant during recovery and disposal are expected to 

occur during activities related to decommissioning refrigeration systems (e.g., attaching of hoses 

associated with draining or otherwise discharging of refrigerant from the refrigeration units into cylinders) 

and would be similar to those during servicing, because similar refrigerant charging and/or recovery 

equipment would be used (see Section 10.2 and Table 9 for information and modeling results related to 

exposure during servicing activities). 

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

activities) are not anticipated to present a significant concern for workers. To model a worst-case scenario 
FINAL July 2, 2015

17 

during disposal for direct rack systems, it was conservatively assumed that 14 percent of the equipment 

charge would be released per disposal event. For beverage coolers and commercial ice machines, it was 

assumed that of the 10 disposal events, 9 units are properly disposed of with only incidental releases of 

refrigerant (i.e., 1 percent per unit) followed by the disposal of one unit that results in a catastrophic 

release of refrigerant (i.e., 100 percent of the equipment charge).

Table 10 displays the maximum estimated 8-hour TWA occupational exposure levels for the R-448A 

components at disposal. Based on the assumptions described in the beginning of Section 10, under the 

disposal release scenarios, the modeling indicates that occupational exposure could exceed the 8-hour long 

term exposure limit for HFC-32 in direct rack systems and for HFC-32, HFC-125, HFC-134a, and HFO1234yf for commercial ice machines. 

Table 10. Occupational Risk Assessment at Disposal for R-448A Componentsa

Equipment R-448A Component 

8-Hour TWA 

Occupational 

Exposure (ppm) 

8-Hour Long Term 

Exposure Limitsb (ppm) 

Direct Rack System 

HFC-32 1,160 1,000

HFC-125 502 1,000

HFC-134a 477 1,000

HFO-1234yf 407 500

HFO-1234ze(E) 142 800

Beverage Cooler 

HFC-32 102 1,000

HFC-125 44 1,000

HFC-134a 42 1,000

HFO-1234yf 36 500

HFO-1234ze(E) 12 800

Ice Machine 

HFC-32 1,700 1,000

HFC-125 735 1,000

HFC-134a 700 1,000

HFO-1234yf 595 500

HFO-1234ze(E) 210 800

Bold font indicates modeling results. 

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

options. 

b

 WEEL OEL 

Although the modeling indicates that the worst-case disposal scenario for the HFC-32 component of R448A in direct rack systems and commercial ice machines and the HFO-1234yf component in commercial 

ice machines exceed the 8-hour exposure limits for these components, 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 also typically 

disposed of by Section 608-certified personnel using proper industrial hygiene techniques to maximize 

recovery efficiency and limit releases. The average recovery efficiencies and maximum disposal release

rates (see Table 10) are also representative of release rates for currently used refrigerants in commercial 

refrigeration equipment (e.g., R-404A, R-507A, R-407C), 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-448A systems). 

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

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

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

the recovered refrigerant) or trapped within deeper parts of the refrigeration circuit (e.g., the accumulator 

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

process (Oko-Recherche 2003). 
FINAL July 2, 2015

18 

Because anticipated occupational exposures could be above the exposure limits for HFC-32 in direct rack 

systems and for HFC-32, HFC-125, HFC-134a, and HFO-1234yf for commercial ice machine disposal 

release scenarios, the recommendations for proper engineering controls and PPE in the SDS for R-448A 

should be followed. Adequate ventilation should always be established during any use, handling, or 

storage of R-448A. 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-448A to prevent dispersion throughout the workplace. In addition, an eye wash and safety shower 

should be near the manufacturing facility and locations where R-448A is stored and ready for use. In 

general, use of PPE is recommended, such as splash goggles, mechanical-resistance gloves (e.g., oilrepellent or thermal resistant gloves) when handling cylinders and chemically-resistant gloves when 

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

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

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

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

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

immediately should they hear the refrigerant detector alarm and/or smell the leaked refrigerant. EPA 

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

hygiene and manufacturing practices and the SDS for R-448A, there is no significant risk to workers 

during the manufacturing, installation, servicing, and disposal of R-448A in retail food refrigeration units 

and commercial ice machines. 

11. GENERAL POPULATION EXPOSURE ASSESSMENT 

R-448A is not expected to cause a significant risk to human health in the general population when 

manufactured for use and used as a refrigerant in retail food refrigeration and commercial ice machines. 

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

systems; thus, significant releases are not anticipated. At room temperature, R-448A is a gas and, 

therefore, releases to ground or surface water are not anticipated, as R-448A 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-448A). Should air releases during 

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

collect R-448A and prevent the release of R-448A 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-448A is not expected to pose a significant 

toxicity risk to the general population. 
FINAL July 2, 2015

19 

12. REFERENCES 

Armines. 2008. Inventory of Direct and Indirect GHG Emissions from Stationary Air Conditioning and 

Refrigeration Sources, with Special Emphasis on Retail Food Refrigeration and Unitary Air Conditioning. 

CARB Agreement No. 06-325. Available at: 

http://www.arb.ca.gov/cc/commref/armines_report_03_625.pdf. 

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

Industrial Hygienists. 

ANSI/ASHRAE. 2015. 2015 Supplement to Standard 34: Designation and Safety Classification of 

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

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

Heating, Refrigerating and Air-Conditioning Engineers, Inc. 

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

Heating, Refrigerating and Air-Conditioning Engineers, Inc. 

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

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

CARB. Gallagher, Glenn, Tao Zhan, Ying-Kuang Hsu, et. al. 2013. “High-global Warming Potential Fgas Emissions in California: Comparison of Ambient-based versus Inventory-based Emission Estimates, 

and Implications of Refined Estimates.” Environ. Sci. Technol., 2014, 48 (2), pp 1084–1093. DOI: 

10.1021/es403447v. Publication Date (Web): December 13, 2013. Copyright © 2013 American Chemical 

Society. Available at http://pubs.acs.org/doi/abs/10.1021/es403447v 

Forster, P., V. Ramaswamy, P. Artaxo, T. Berntsen, R. Betts, D.W. Fahey, J. Haywood, J. Lean, D.C. 

Lowe, G. Myhre, J. Nganga, R. Prinn, G. Raga, M. Schulz and R. Van Dorland. 2007. Changes in 

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

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

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

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

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

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

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

doi:10.1002/rog.20013. 

Honeywell, Inc. 2014a. Solstice® N-40 (R-448A). Significant New Alternatives Policy Program 

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

Honeywell, Inc. 2014b. Response to Incompleteness Letter for Solstice® N-40 (R-448A) Significant New 

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

11, 2014. 

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

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

London, CT. 
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IPCC. 2013. Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the 

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