Final -- October 10, 2014

1

Significant New Alternatives Policy Program 

Refrigeration and Air Conditioning Sector

Risk Screen on Substitutes in Refrigerated Transport

Substitute: R-450A

This risk screen does not contain Clean Air Act (CAA) Confidential Business Information 

(CBI) and, therefore, may be disclosed to the public.

1. INTRODUCTION

Ozone-depleting substances (ODS) are being phased out of production in response to a series of diplomatic 

and legislative efforts that have taken place over the past two decades, including the Montreal Protocol and 

the Clean Air Act Amendments of 1990 (CAAA). The U.S. Environmental Protection Agency (EPA), as 

authorized by Section 612 of the CAAA, administers the Significant New Alternatives Policy (SNAP) 

Program, which identifies acceptable and unacceptable substitutes for ODS in specific end-uses based on 

assessment of their health and environmental impacts. 

EPA’s decision on the acceptability of a substitute is based on the findings of a screening assessment of 

potential human health and environmental risks posed by the substitute in specific applications. EPA has 

already screened a large number of substitutes in many end-use applications within all of the major ODSusing sectors including: refrigeration and air conditioning, solvent cleaning, foam blowing, aerosols, fire 

suppression, adhesives, coatings and inks, and sterilization. The results of these risk screens are presented 

in a series of Background Documents that are available in EPA's docket.

The purpose of this risk screen is to supplement EPA’s Background Document on the refrigeration and air 

conditioning sector (EPA 1994) (hereinafter referred to as the Background Document). This risk screen 

evaluates the potential use of R-450A as a substitute in the refrigerated transport end-use, specifically in

containers, trailers, and ship holds. Table 1 presents the composition of the proposed substitute.

Table 1. Composition of R-450A and Potential Impurities

Constituent Chemical Formula CAS Number Concentration

(Weight Percent)a

1,1,1,2-Tetrafluoroethane (HFC-134a) CF3CH2F 811-97-2 42%

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

(HFO-1234ze(E)) CHFCHCF3 29118-24-9 58%

Potential Impurities
Final -- October 10, 2014

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

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

 Section 3: Atmospheric Assessment

 Section 4: Volatile Organic Compound Assessment 

 Section 5: Discussion of End-Use Scenario Modeled 

 Section 6: Potential Health Effects

 Section 7: Flammability Assessment

 Section 8: Asphyxiation Assessment 

 Section 9: End-Use Exposure Assessment

 Section 10: Occupational Exposure Assessment 

 Section 11: General Population Exposure Assessment

 Section 12: References

2. SUMMARY OF RESULTS

R-450A is recommended for SNAP approval for the refrigerated transport end-use, specifically containers, 

trailers, and ship holds. EPA's risk screen indicates that the use of the proposed substitute will be less 

harmful to the atmosphere than the continued use of commonly used refrigerants such as CFC-12, R-502, 

and HCFC-22, as it is less harmful to the ozone layer, has lower climate impact, and a shorter atmospheric 

lifetime. Neither of the components of R-450A are subject to volatile organic compound (VOC) 

regulations under the CAA (40 CFR 51.100(s)), so environmental impact from the release of these 

substances is not a concern. It is expected that the material safety data sheet (MSDS) for R-450A and good 

manufacturing practices will be adhered to, 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-450A. 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-450A 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-450A in refrigerated transport end-use, 

significant toxicity risk to consumers is also unlikely. In addition, because R-450A is considered to be 

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

safeguards, including specified refrigerant concentration limits (RCL) of R-450A 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 34,2and 62.3

3. ATMOSPHERIC ASSESSMENT

This section presents an assessment of the potential risks to atmospheric integrity posed by the use of R450A in refrigerated transport. The ozone depletion potential (ODP), global warming potential (GWP), and 

atmospheric lifetime (ALT) of the proposed substitute are presented in Table 2.

 

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.
Final -- October 10, 2014

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

shorter atmospheric lifetime when compared to refrigerants currently used in refrigerated transport, such as 

CFC-12, R-502, and HCFC-22. In addition, R-450A also has lower climate impact and a shorter 

atmospheric lifetime than those predicted for other substitutes examined in the Background Document as 

well as commonly utilized refrigerants HFC-134a, R-404A, R-507A, and R-407C. Thus, EPA believes that 

the use of R-450A would result in substantially less harm to the climate and ozone layer than the continued 

use of ODS and other commonly used refrigerants.

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

Refrigerant Ozone Depleting Potential

(ODP)

a

Global Warming Potential

(GWP)

b

Atmospheric Lifetime in 

Years (ALT)

R-450A 0 601 NAc

Individual Components

HFC-134a 0 1,430 14b

HFO-1234ze(E) 0 1

d 16.4 daysd

CFC-12 0.82 10,900 100b

R-502e 0.2 4,650 NAf

HCFC-22 0.13 1,810 12a

HFC-134a 0 1,430 14b

R-404Ag 0 3,922 NAh

R-507Ai 0 3,985 NAj

R-407Ck 0 1,774 NAl

a WMO 2010 Scientific Assessment Report (2011)

b

IPCC 4th Assessment Report (Forster et al. 2007)

c Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for HFC-134a is 14 years and

the ALT for HFO-1234ze(E) is 10 days (IPCC 4th Assessment Report [Forster et al. 2007], Hodnebrog, O. et al. [2013]).

d Hodnebrog, O. et al. (2013)

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

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

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

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

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

ALT for HFC-125 is 29 years, and the ALT for HFC-134a is 14 years (IPCC 4th Assessment Report [Forster et al. 2007]).

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

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

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

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

l Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for HFC-32 is 4.9 years, the ALT

for HFC-125 is 29 years, and the ALT for HFC-134a is 14 years (IPCC 4th Assessment Report [Forster et al. 2007]).

4. VOLATILE ORGANIC COMPOUND (VOC) ANALYSIS

HFC-134a and HFO-1234ze(E) are not volatile organic compounds (VOCs) according to CAA regulations 

(40 CFR 51.100(s)) due to their negligible photochemical reactivity. Therefore, environmental impacts 

from the release of HFC-134a and HFO-1234ze(E) as VOCs are not a concern. 

5. DISCUSSION OF END-USE SCENARIOS MODELED

R-450A has been proposed for use in refrigerated transport units. As provided by the submitter, the typical 

and maximum charge sizes for R-450A in containers, trailers, and ship holds are listed in Table 3. 

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

End-Use Application Typical Charge Size

(kg)

Maximum Charge Size

(kg)

Refrigerated 

Transport

Containers 4 5

Trailers 6.5 10
Final -- October 10, 2014

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Ship Holds 100 >500

To evaluate potential end-use exposures for R-450A in refrigerated transport units, this risk screen 

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

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

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

container doors are open, because EPA expects the refrigerated container door 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-450A in the container as it exchanges with the warm, outside 

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

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

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

container with the door closed. Although R-450A 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 was 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, 9, and 10.

 

4Ventilation rates range from 0 to 60 m3

/hr depending on the type of good that is transported (Hamburg Süd 2010). 
Final -- October 10, 2014

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Table 4. End-Use Scenario Model Assumptions 

Parameter Assumptions

(Containers)

Assumptions

(Trailers)

Assumptions

(Ship Holds)

Refrigerated Transport

Container Containers Trailers Ship Holds

Charge Size (kg) 4;5 6.5;10 100;>500

Length of Release (minutes) 1 1 1

Container Size (volume - m3) 66 (2,360 ft3)

a 100 (3,530 ft3

)

b 7,560 (267,000 ft3

)

c

Room Ventilation (m3/hr) 25 25 25

Vertical Concentration 

Gradient No No No

a Specific information was not available regarding the sizes of the refrigerated transport containers. Thus, a standard 40 ft. (12.2 m)

refrigerated container was used for this scenario, with a height of 7.75 ft (2.4 m) (TRAC Intermodal, 2013).

b According to the United Nations Environmental Programme (UNEP), trailers have box volumes of approximately 100 m3

(UNEP 2010).

c UNEP reported 7,560 m3

(267,000 ft3) as the average volume of a reefer ship above 100 gross tonnes (10,000 ft3) (UNEP 2006).

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-450A in refrigerated transport does not present risk 

to end-users or servicing technicians.

6. POTENTIAL HEALTH EFFECTS

To assess potential health risks from exposure to the proposed substitute in refrigerated transport end-uses, 

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

for different scenarios. In March 2014, R-450A was submitted to ASHRAE’s Standing Standard Project 

Committee (SSPC) for inclusion in ASHRAE Standard 34 under safety group A1 with a refrigeration 

concentration limit (RCL) of 72,000 ppm. ASHRAE 34 RCLs are intended to reduce the risks of acute 

toxicity, asphyxiation, and flammability hazards in normally occupied, enclosed spaces during refrigerant 

use and protect end-users from the potential dangers of a catastrophic leak from refrigeration unit 

(ASHRAE 2010b). ASHRAE Standard 15 implements the aforementioned standard, requiring that “the 

concentration of refrigerant in an enclosed space following a complete discharge of a high-probability 

system shall not exceed the RCL” (ASHRAE 2010a). As such, this risk screen references the proposed 

RCL for R-450A in addition to the lower flammability limit, hypoxia no observed adverse effect level 

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

asphyxiation, and end-use exposure risks, respectively, do not occur.

For the occupational exposure analysis, potential risks from chronic and acute worker exposure were 

evaluated by comparing exposure concentrations to available occupational exposure limits. Potential risks 

of chronic worker exposure were evaluated using workplace guidance levels (WGL). Risks from potential 

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

guidance levels (EGL). In the absence of an established short-term exposure limit (STEL), acute exposure 

guideline level (AEGL), or emergency response planning guideline (ERPG) for R-450A, potential shortterm, end-use exposures were evaluated on a component basis (i.e., HFC-134a and HFO-1234ze(E)).

Table 5 lists the relevant toxicity limits for R-450A and its components and is followed by Table 6, which 

provides an explanation of each toxicity limit. EPA’s approach for identifying or developing these values 

is discussed in Chapter 3 of the Background Document. 
Final -- October 10, 2014

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Table 5. Exposure Limits of R-450A Components

R-450A 

Component

WGL

(Long-term Exposure)

ppm

EGL 

(Short-term Exposure)

ppm

Refrigerant Concentration 

Limit (RCL)

ppm

R-450A 880 (8-hour AEL) 2,640 (15-min STEL)

a 72,000

Individual Components

HFC-134a 1,000 (8-hour WEEL)

8,000 (10-min AEGL-1)

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

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

b NAc

NA = Not available

a Neither ACGIH nor AIHA recommend ceiling or short term exposure limits for the blend R-450A. A STEL for R-450A of 2,640 ppm was 

developed by EPA based on the 880 ppm AEL value. The STEL was estimated as three to five times the AEL, which is an established method of 

estimating a short-term exposure limit by ACGIH. [STEL] = [AEL] x 3 = 880 ppm x 3 ≈ 2,640 ppm

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

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

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

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

Table 6. Explanation of Exposure Limit-Related Terminologya

Organization Definition

OSHA Occupational Safety and Health Administration

NIOSH National Institute for Occupational Safety and Health

ACGIH American Conference of Governmental Industrial Hygienists

AIHA American Industrial Hygiene Association

OARS Occupational Alliance for Risk Science

Exposure Limit Definition Explanation

Short-Term Exposure

RCL Refrigerant Concentration 

Limit

The RCL for a refrigerant is intended to reduce the risks of acute toxicity, 

asphyxiation, and flammability hazards in normally occupied, enclosed 

spaces. The RCL for each refrigerant is the lowest of the Acute-Toxicity 

Exposure Limit (ATEL), Oxygen Deprivation Limit (ODL), and Flammable 

Concentration Limit (FCL). Determination assumes full vaporization with 

no removal by ventilation, dissolution, reaction, or decomposition and 

complete mixing of refrigerant in the space to which it is released.

ATEL Acute Toxicity Exposure Limit The ATEL is the refrigerant concentration limit intended to reduce the 

risks of acute toxicity hazards in normally occupied, enclosed spaces 

according to ASHRAE Standard 34. The ATEL includes consideration of 

mortality, cardiac sensitization, anesthetic or central nervous system 

effects and other escape impairing effects and permanent injury. The 

ATEL is similar to the Immediately Dangerous to Life or Health (IDLH)

concentrations set by NIOSH.

STEL Short-Term Exposure Limit A 15-minute time-weighted average (TWA) exposure that should not be 

exceeded during a workday, even if the 8-hour TWA is within the TLV–

TWA, set by ACGIH. 

AEGLb,c

Acute Exposure Guideline 

Level 1

AEGL-1 is the airborne concentration of a substance above which it is 

predicted that the general population, including susceptible individuals, 

could experience notable discomfort, irritation, or certain asymptomatic 

nonsensory effects. However, the effects are not disabling and are 

transient and reversible upon cessation of exposure.

Acute Exposure Guideline 

Level 2

AEGL-2 is the airborne concentration (expressed as ppm or mg/m3) of a 

substance above which it is predicted that the general population, 

including susceptible individuals, could experience irreversible or other 
Final -- October 10, 2014

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serious, long-lasting adverse health effects or an impaired ability to 

escape.

Acute Exposure Guideline 

Level 3

AEGL-3 is the airborne concentration (expressed as ppm or mg/m3) of a 

substance above which it is predicted that the general population, 

including susceptible individuals, could experience life-threatening health 

effects or death.

Long-Term Exposure

PEL Permissible Exposure Limit This is an 8-hour time-weighted average exposure limit set by OSHA. 

AEL Acceptable Exposure Limit The maximum 8-hour time weighted average (TWA) at which a worker 

can be exposed regularly without adverse effects.

WEEL Workplace Environmental 

Exposure Level

Developed by OARS for to protect healthy workers against acute and 

chronic health effects, this limit is based on repeated daily exposures 

over a working lifetime and averaged over an 8-hour workday. 

TLV-TWA Threshold Limit Value –TimeWeighted AverageThe TWA concentration for a conventional 8-hour workday and a 40-

hour workweek, to which it is believed that nearly all workers may be 

repeatedly exposed, day after day, for a working lifetime without adverse 

effect according to ACGIH. 

a All information in this table taken from EPA (1994) except where otherwise noted.

b EPA (2012)

c Applicable to emergency exposure periods ranging from 10 minutes to 8 hours.

According to the MSDS, exposure to R-450A may be hazardous if inhalation, skin contact, or eye contact 

with R-450A occurs. The most likely pathway of exposure is through inhalation. R-450A can cause 

symptoms of asphyxiation when present in concentrations high enough to significantly lower oxygen 

concentrations below 19.5 percent by volume, such as headaches, ringing in ears, dizziness, drowsiness, 

nausea, vomiting, depression of all senses, and also unconsciousness. Under some circumstances of overexposure (i.e., oxygen levels fall below 6 percent by volume), death may occur. 

If R-450A is inhaled, person(s) should be immediately removed and exposed to fresh air. In accordance 

with the MSDS, EPA further recommends that if breathing is difficult or irregular, person(s) be given 

oxygen, provided a qualified operator is present, and medical attention be sought. Rescuers should not 

attempt to retrieve victims of exposure to R-450A without adequate PPE. At a minimum, a self-contained 

breathing apparatus (SCBA) should be worn. Exposures of R-450A to the skin may cause frostbite. In the 

case of dermal exposure, the MSDS for R-450A recommends that person(s) immediately wash the affected 

area with water and remove all contaminated clothing; if frostbite occurs, bathe (not rub) the affected area 

with lukewarm, not hot, water. If water is not available, cover the affected area with a clean, soft cloth, and 

seek medical attention immediately. Exposures of R-450A to the eyes could cause eye irritation. In case of 

ocular exposure, the MSDS for R-450A recommends that person(s) immediately flush the eyes, including 

under the eyelids, with copious amounts of water for 15 minutes. 

EPA’s review of the human health impacts of this proposed substitute is contained in the public docket for 

this decision. These risks and procedures after exposure are similar for other common refrigerants. The 

potential health effects of R-450A can be minimized by following the exposure guidelines and ventilation 

and PPE recommendations outlined in the MSDS for R-450A and this risk screen.
Final -- October 10, 2014

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7. FLAMMABILITY ASSESSMENT

R-450A has been submitted to the ASHRAE SSPC 34 committee for classification as an A1 refrigerant, 

and is considered to be nonflammable (Honeywell 2014). Based on this classification, manufacture, 

servicing, and use of R-450A is not expected to present a flammability risk in refrigerated transport.

8. ASPHYXIATION ASSESSMENT

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

asphyxiation is assessed in three ways: 1) modeling the oxygen concentration under the charge size and 

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

size needed to cause an asphyxiation risk in the room size specified in the worst-case scenario 3) 

performing a threshold analysis of the maximum container size needed to cause an asphyxiation risk with 

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

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

exposed, such as open doors, which allow air to flow in and out. As specified in Section 5, the worst-case 

scenario does not assume a vertical concentration gradient. If the proposed substitute passes the screening 

analysis with these restrictive assumptions in place, it can be reasonably assumed that no risks of 

asphyxiation will be present under 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

Containers Scenario 1a 5 66 (2,360 ft3) 21

Trailers Scenario 1b 10 100 (3,530 ft3) 21

Ship Holds Scenario 1c 500 7,560 (267,000 ft3) 21

Minimum Container Size Threshold Analysis 1a: Charge Size 126 66 (2,360 ft3)

12 Maximum Container Size Threshold Analysis 1b: Charge Size 14,610 7,560 (267,000 ft3

)

Minimum Charge Size Threshold Analysis 2a: Container Size 4 2.1 (74 ft3)

Maximum Charge Size Threshold Analysis 2b: Container Size 500 261.8 (9,245 ft3)

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).

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 reasonable worst-case scenario modeling, a release of R-450A in 

refrigerated transport units 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 or openings at the 

bottom of container doors that allow air to flow in and out, as mentioned above, 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 the smallest container size of 66 m3

(2,360 ft3), as shown under Threshold Analysis 1a, the charge size of the R-450A refrigeration unit would 

have to be at least 126 kg for asphyxiation to be a concern, which is more than thirty times greater than the 

minimum charge size indicated by the submitter (i.e., 4 kg). Using the largest charge size of 500 kg, as 

 

5 Twelve percent oxygen in air is the NOAEL for hypoxia (ICF 1997). 
Final -- October 10, 2014

9

shown under Threshold Analysis 2b, the volume of the container would have to be approximately 262 m3 

(9,245 ft3) or smaller 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 R450A 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 MSDS for R-450A.

9. END-USE EXPOSURE ASSESSMENT

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

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

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

R-450A 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 door is opened, a stack effect exists from the presence of the denser, cold air 

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

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

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

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

open, increasing the air exchange rate inside of the unit and also resulting in diffusion of any R-450A 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-450A, which were then compared to the 

standard toxicity limits presented in Table 5 to assess the risk to end-users. Because HFO-1234ze(E) is 

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

8b only display exposures for HFO-1234ze(E), the component with greater potential concerns. Modeling 

results are presented in Table 8a.

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

Refrigerated 

Transport 

Containers

Scenario Charge 

Size (kg)

Room Size 

(m3)

15-min TWA EndUse Exposure 

(ppm)

Exposure Limit (ppm)b

Short-term 

(15-min) 

Acute 

toxicity

Containers Worst-Case Scenario 1a 466 6,500

2,400 59,000

Worst-Case Scenario 1b 5 8,100

Trailers Worst-Case Scenario 1c 6.5 100 7,200

Worst-Case Scenario 1d 10 11,000

Ship Holds Worst-Case Scenario 1e 100 7,560 1,530

Worst-Case Scenario 1f 500 4,090

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.

b See Table 5 for more information

Under the worst-case scenarios described in Section 5 for refrigerated transport systems in containers, 

trailers, and ship holds, catastrophic releases of the typical and maximum charge sizes of R-450A were 

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

STEL (i.e., 2,400 ppm) (see Table 8a), the STEL is a conservatively-derived exposure limit that is 
Final -- October 10, 2014

10

intended to protect against risk with a wide safety margin for even the most sensitive of populations. All of 

these exposure estimates are significantly lower than the acute toxicity exposure limit (ATEL) of 59,000 

ppm for HFO-1234ze(E), which is a refrigerant concentration limit intended to reduce the risks of acute 

toxicity hazards in normally occupied, enclosed spaces according to ASHRAE Standard 34. Furthermore, 

the estimated exposures for R-450A in each of these scenarios are also significantly lower than the RCL 

for R-450A (i.e., 72,000 ppm). Because the modeling was done using a conservative worst-case scenario 

where the refrigerated transport container door is closed, and because normally personnel would be 

exposed in a situation where the door is open with significantly higher ventilation levels, personnel 

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

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

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

a 25 m3/hr ventilation rate that would avoid end-use exposures above the STEL for HFO-1234ze(E) (i.e., 

2,400 ppm). The results from the threshold analyses are used to establish general guidelines for choosing 

an effective container size and charge size such that the use of R-450A 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 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 – Charge and Container Sizes

Refrigerated 

Transport 

Container

Scenario Charge Size 

(kg) Container Size (m3

)

End-Use 

Exposure

(ppm)

Containers Threshold Analysis 1a: Charge Size 1.5 66 (630 ft3)

2,400a

Trailers Threshold Analysis 1b: Charge Size 2.2 100 (3,000 ft3)

Ship Holds Threshold Analysis 1c: Charge Size 160 7,560 (267,000 ft3)

Containers Threshold Analysis 2a: Container Size 5 240 (8,340 ft3)

Trailers Threshold Analysis 2b: Container Size 10 480 (16,900 ft3)

Ship Holds Threshold Analysis 2c: Container Size 500 24,200 (835,350 ft3)

Bold font indicates modeling results.

a EPA-derived STEL (see Table 5).

Based on these results, for a minimum container volume of 66 m3(630 ft3), end-use exposure above the 

STEL would not be a concern as long as the charge size does not exceed 1.5 kilograms (see Threshold 

Analysis 1a in Table 8b) and for the maximum proposed charge sizes in containers, trailers, and ship holds 

(i.e. 5, 10, and 500, kilograms, respectively) exposure would not be a concern if the refrigeration unit is 

installed in a container of effective volume of at least 240 m3 (8,340 ft3), 480 m3(16,900 ft3), and 24,200 

m3(835,350 ft3), respectively (see Threshold Analyses 2a, 2b, and 2c in Table 8b). As shown in Table 8b, 

these recommended minimum container sizes vary in direct correlation with charge size, and are more 

conservative than the intended charge sizes provided by the submitter. However, these modeling results 

presented in Table 8a and 8b are derived using the STEL (i.e., 2,400 ppm), which is the most conservative 

short-term exposure limit for HFO-1234ze(E) and reflect conditions that are assumed to be a worst-case 

scenario, as described in Section 5.

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

approximately 2,520 m3/hr, which is roughly 100 times the ventilation rates used in the threshold analyses 

(Bonjour et. al 2011). As previously discussed, EPA expects the refrigerated container door 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-450A to flow towards the outside air. Therefore, under a reasonable

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

results (see Tables 8a and 8b) are unlikely.
Final -- October 10, 2014

11

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

worst-case scenario where the refrigerated transport container door is closed, personnel exposure above the 

proposed substitute’s STEL of 2,400 ppm 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-450A system is installed, EPA 

recommends that the proposed RCL for R-450A (i.e., 72,000 ppm or 320 g/m3) and the ATEL for the 

individual components (i.e., 59,000 ppm for HFO-1234ze(E) and 50,000 ppm for HFC-134a) are not 

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

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

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

inside. In addition, EPA recommends that warning labels are present in the refrigerated transport container 

indicating that R-450A refrigerant is in use and can cause suffocation, injury, or death. An example of this 

warning label would read: “WARNING: R-450A gas can cause injury or death. Ventilate the area before 

entering. A high R-450A 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-450A, 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-450A leakage.

10. OCCUPATIONAL EXPOSURE ASSESSMENT

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

disposal of R-450A refrigerated transport equipment. To ensure that use of the proposed substitute in 

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

disposal, occupational exposure modeling was performed using a box-model approach. For a detailed 

description of the methodology used for this screening assessment, the reader is referred to the 

occupational exposure and hazard analysis described in Chapter 5 of the Background Document.

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

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

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

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

shown. The release rate per event was multiplied by the number of events estimated to occur over a 

workday. The release per event was conservatively assumed to range between 0.6 percent and 8 percent of 

the equipment charge during charging and servicing, respectively (see Section 10.2) and 20 percent7 of the 

equipment charge during disposal (see Section 10.3). 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 trailers and rail 

cars and one unit divided by eight hours per workday for refrigerated units in ship holds). For disposal, it 

was conservatively assumed that 10 units are disposed during an 8-hour work day for containers and 

trailers equipment and one unit per day for ship hold systems. The modeled exposure concentrations were 

compared to short-term occupational exposure limits at charging and servicing and long-term exposure 

 

6

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

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

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

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

initial ODS substance that the equipment contained. 

7 CARB (2013) estimates an end-of-life loss rate of 13-19% for refrigerated transport systems and DECC (2011) estimates a 

disposal loss rate of 20-30%. A proposed update to EPA’s Vintaging Model recommends an end-of-life loss rate of 20% based on 

these estimates and other assumptions found in recent literature.
Final -- October 10, 2014

12

limits at disposal. Similar to the end-use exposure assessment, Tables 9 and 11 only present exposures for 

HFO-1234ze(E), the component with greater potential concerns. 

10.1 Occupational Exposure at Manufacture

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

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

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

PPE used. 

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

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

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

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

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

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

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

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

respiratory protection (including a self-contained breathing apparatus [SCBA] in case of insufficient 

ventilation), tightly sealed goggles, and protective gloves (OSHA 1994).

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

such as hydrogen fluoride and hydrogen chloride if HFC-134a or HFO-1234ze(E) are exposed to high 

temperatures or fire. Other reaction products such as carbon dioxide might also be present. Containers 

should be stored in cool, dry conditions (maximum storage temperature should be 40C) in well-sealed 

receptacles and should not be allowed to contact open flames, glowing metal surfaces, or electrical heating 

elements. EPA believes that when proper handling and disposal guidelines are followed in accordance with 

both good industrial hygiene and manufacturing practices and the MSDS for R-450A and its components, 

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

10.2 Occupational Exposure at Charging and Servicing

As indicated by the submitter, large refrigeration equipment (e.g., refrigerated transport units in ship holds) 

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

(e.g. refrigeration units in containers and trailers) would occur by the Original Equipment Manufacturer 

(OEM). For both OEM system manufacture (i.e. charging at OEM location) and field charging (i.e., 

charging at the end-use location), points of release for charging and servicing these leak-tight systems 

would be from connection/disconnection of temporary lines for charging and recovery equipment). 

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

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

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

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

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

During servicing, used refrigerant from R-450A in refrigerated transport units is pumped into a canister, 

where it is stored until it is recycled (i.e., filtered and reclaimed/sold). During the transfer to the initial 

canister, incidental refrigerant releases may occur during connection and disconnection of the recharging 

hose fittings (Honeywell 2014). Isolation and evacuation of lines or equipment prior to servicing or repair 

and the use of compatible seals, gaskets, O-rings, thread sealants, and minimization of threaded joints all 

contribute to limiting releases. Ventilation, leak monitors, and alarms also help minimize exposure.
Final -- October 10, 2014

13

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-450A MSDS and 

maintenance manual, undergo proper training, and wear appropriate PPE (e.g., gloves and safety glasses). 

Nevertheless, the potential occupational exposure during servicing was analyzed. The maximum 15-

minute time weighted average (TWA) exposures for each R-450A constituent were estimated for the 

servicing exposure scenario and compared to their respective short-term exposure limits (see Table 9). 

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

HFC-134a, Table 9 only presents exposures for HFO-1234ze(E), the component with greater potential 

concerns.

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

Equipment Scenario

Charge 

Size 

(kg)

15-minute TWA Occupational 

Exposure (ppm)

15-min Short 

Term 

Exposure 

Limits (ppm)

Charging 

[0.6% release]

Servicing 

[8% release]

Containers Reasonable Worst-Case Scenario 1a 4 17 220

2,400c

Reasonable Worst-Case Scenario 1b 5 21 280

Trailers Reasonable Worst-Case Scenario 1c 6.5 27 360

Reasonable Worst-Case Scenario 1d 10 41 550

Ship Holdsb

Reasonable Worst-Case Scenario 1e 100 41 550

Reasonable Worst-Case Scenario 1f 500 210 2,800

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 One installation or servicing event per day was modeled for refrigerated transport units in ship holds

c EPA-derived STEL (see Table 5)

The anticipated 15-minute TWA exposures for the HFO-1234ze(E) component of R-450A are not 

anticipated to exceed its STEL (i.e., 2,400 ppm) for all scenarios except the maximum charge size for ship 

holds in Reasonable Worst-Case Scenario 1f (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-450A presents 

a significant concern to workers.

10.3 Occupational Exposure at Disposal

Disposal of R-450A in refrigerated transport units is expected to occur with limited frequency 

(approximately one disposal event per day) at disposal facilities and with limited duration of exposure to 

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

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

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

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

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

related to exposure during servicing activities). 

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

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

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

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

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

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

14

Table 10. Assumed Release Rates during Disposal

End-Use Percent Remaining 

at Disposal

Recovery 

Efficiency

Implied Maximum 

Disposal Release Rate

Refrigerated Transport Unit 50% 60% 20%

Source: Release rate assumptions consistent with CARB (2013) and DECC (2011) estimates.

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

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

HFO-1234ze(E), the component with greater potential concerns.

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

Equipment Scenario Maximum 

Charge Size (kg)

8-hour TWA Occupational 

Exposure (ppm)

8-Hour Long

Term Exposure 

Limits (ppm)

Containers Reasonable Worst-Case Scenario 1a 4 510

800b

Reasonable Worst-Case Scenario 1b 5 630

Trailers Reasonable Worst-Case Scenario 1c 6.5 820

Reasonable Worst-Case Scenario 1d 10 1,300

Ship Holds Reasonable Worst-Case Scenario 1e 100 1,600

Reasonable Worst-Case Scenario 1f 500 7,900

Bold font indicates modeling results.

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

b 8-hour WEEL

The results in Table 11 indicate that long-term (8-hour) worker exposure concentrations of the HFO1234ze(E) component of R-450A are not likely to exceed its WEEL (i.e. 800 ppm) in containers. The 

reasonable worst-case disposal modeling for trailers and ship holds indicates worker exposure 

concentrations could exceed the WEEL for HFO-1234ze(E). Although the modeling indicates that the 

worse-case disposal scenario could exceed the WEEL for HFO-1234ze(E), the estimated exposures were 

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

worst-case scenario with a low probability of occurrence (e.g., for smaller refrigerated transport units, it is 

highly unlikely that a worker would be exposed to the maximum release rate at disposal for every unit 

decommissioned in a day). These types of systems are typically disposed of by Section 608-certified 

personnel using proper industrial hygiene techniques to maximize recovery efficiency and limit releases. 

The average recovery efficiency and maximum disposal release rate (see Table 10) are also representative 

of release rates for currently used refrigerants in refrigerated transport units (e.g., HFC-134a), 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-450A 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). 

Because anticipated occupational exposures could exceed the exposure limit for HFO-1234ze(E) for some 

of the disposal release scenarios (i.e., Reasonable Worst-Case Scenarios 1c through 1f) for refrigerated 

transport applications, the recommendations for proper engineering controls and PPE in the MSDS for R450A should be followed. Adequate ventilation should always be established during any use, handling, or 

storage of R-450A. If recovery and disposal is taking place in an enclosed space without any mechanical 
Final -- October 10, 2014

15

ventilation, facilities should be cleared of non-essential personnel and technicians should wear a SCBA 

and other appropriate protective equipment.

Engineering controls should include vapor-in air detection systems and local exhaust ventilation during use 

of R-450A to prevent dispersion throughout the workplace. In addition, an eye wash and safety shower 

should be near the manufacturing facility and locations where R-450A is stored and ready for use. In 

general, use of PPE is recommended, such as splash goggles, mechanical resistance gloves (e.g., oilrepellent or thermal 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) 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 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 MSDS for R-450A, there is no significant risk to workers during the 

manufacturing, installation, servicing, and disposal of R-450A in refrigerated transport units.

11. GENERAL POPULATION EXPOSURE ASSESSMENT

R-450A is not expected to cause a significant risk to human health in the general population when

manufactured for use and used as a refrigerant in 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-450A is a gas and, therefore, releases to ground or surface 

water are not anticipated, as R-450A is anticipated to dissipate into the atmosphere upon release to outside 

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

concentration of R-450A). Should air releases during manufacturing operations occur, engineering controls 

should be used (e.g., carbon absorption scrubbers) to collect R-450A and prevent the release of R-450A to 

the atmosphere. EPA believes that by using proper engineering controls and by following disposal and 

containment recommendations outlined in the proposed substitute’s MSDS, exposure to R-450A is not 

expected to pose a significant toxicity risk to the general population.
Final -- October 10, 2014

16

12. REFERENCES

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

Industrial Hygienists.

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.

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

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

Bonjour, J. Ducoulombier, M., and Sartre, V. 2011. Experimental Investigation of the Infiltration Heat Load 

During the Opening of a Refrigerated Truck Body. International Institute of Refrigeration: International 

Congress of Refrigeration. Available online at http://bright-blue.eu/wp-content/uploads/2012/11/artikel392_DucoulombierSartreBonjour_revised_final.pdf. 

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.

Gallagher, Glenn, Tao Zhan, Ying-Kuang Hsu, et. al. (CARB) 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

Hodnebrog, O., 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. 2014. Solstice® N-13 (R-540) in Retail Food Refrigeration and Vending Machines. 

Significant New Alternatives Policy Program Submission to the United States Environmental Protection 

Agency. May 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.

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

Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. 

Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. 

Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.

IPCC/TEAP. 2005. Bert Metz, Lambert Kuijpers, Susan Solomon, Stephen O. Andersen, Ogunlade 

Davidson, José Pons, David de Jager, Tahl Kestin, Martin Manning, and Leo Meyer (Eds). Safeguarding 
Final -- October 10, 2014

17

the Ozone Layer and the Global Climate System. Intergovernmental Panel on climate Change 

Technology and Economic Assessment Panel. Cambridge University Press, UK. pp 478.

Kataoka, O., M. Yoshizawa, & T. Hirakawa 2000. “Allowable Charge Limit of Flammable Refrigerants 

and Ventilation Requirements.” Daikin Industries. International Refrigeration and Air Conditioning 

Conference. Paper 506. Available online at: http://docs.lib.purdue.edu/iracc/506.

Mackenzie, F.T. and J.A. Mackenzie. 1995. Our changing planet. Prentice-Hall.

OSHA. 2004. “Safety and Health Topics: Isobutane.” February 2004. Available online at: 

<http://www.osha.gov/dts/chemicalsampling/data/CH_247840.html>.

TRAC Intermodal. 2013. “Intermodal Industry Overview – History of Containers and Intermodal 

Industry”. Available online at: <http://www.tracintermodal.com/wpcontent/uploads/PDFs/Introduction%20to%20Intermodal%20Industry%20-%20TRAC.pdf>.

United Nations Environmental Programme. 2006. “2006 Report of the Refrigeration, Air Conditioning 

and Heat Pumps Technical Options Committee (RTOC) 2006 Assessment. Available online at: <

http://ozone.unep.org/Assessment_Panels/TEAP/Reports/RTOC/rtoc_assessment_report06.pdf>

United Nations Environmental Programme. 2010. “2010 Report of the Refrigeration, Air Conditioning 

and Heat Pumps Technical Options Committee (RTOC) 2006 Assessment. Available online at: http://acdext.gsfc.nasa.gov/Documents/O3_Assessments/Docs/WMO_2010/2010assessment/RTOC_2010_Assess

ment_Report.pdf>

UK Department of Energy & Climate Change (DECC). 2011. “Development of the GHG Refrigeration 

and Air Conditioning Model.” Prepared by ICF International. November 2011. Available at 

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/48250/3844-greenhousegas-inventory-improvement-project-deve.PDF. 

U.S. EPA 1994. Significant New Alternatives Policy Technical Background Document: Risk Screen on 

the Use of Substitutes for Class I Ozone-depleting Substances: Refrigeration and Air Conditioning. 

Stratospheric Protection Division. March, 1994.

U.S. EPA. 2012. Acute Exposure Guidelines (AEGLs) Definitions. Available online at: 

http://www.epa.gov/oppt/aegl/pubs/define.htm.

WMO (World Meteorological Organization), 2011. Scientific Assessment of Ozone Depletion: 2010, 

Global Ozone Research and Monitoring Project-Report No. 52, 516 pp., Geneva, Switzerland.