17488 Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011 / Rules and Regulations 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 82 

[EPA–HQ–OAR–2008–0664; FRL–9275–8] 

RIN 2060–AP11 

Protection of Stratospheric Ozone: 

New Substitute in the Motor Vehicle Air 

Conditioning Sector Under the 

Significant New Alternatives Policy 

(SNAP) Program 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: The Environmental Protection 

Agency’s (EPA) Significant New 

Alternatives Policy (SNAP) program is 

expanding the list of acceptable 

substitutes for use in the motor vehicle 

air conditioning end-use as a 

replacement for ozone-depleting 

substances. The Clean Air Act requires 

EPA to review alternatives for ozonedepleting substances and to disapprove 

substitutes that present overall risks to 

human health and the environment 

more significant than those presented by 

other alternatives that are available or 

potentially available. The substitute 

addressed in this final rule is for use in 

new passenger cars and light-duty 

trucks in the motor vehicle air 

conditioning end-use within the 

refrigeration and air conditioning sector. 

EPA finds hydrofluoroolefin (HFO)– 

1234yf acceptable, subject to use 

conditions, as a substitute for 

chlorofluorocarbon (CFC)-12 in motor 

vehicle air conditioning for new 

passenger cars and light-duty trucks. 

The substitute is a non-ozone-depleting 

gas and consequently does not 

contribute to stratospheric ozone 

depletion. 

DATES: This final rule is effective on 

May 31, 2011. The incorporation by 

reference of certain publications listed 

in the rule is approved by the Director 

of the Federal Register as of May 31, 

2011. 

ADDRESSES: EPA has established a 

docket for this action under Docket ID 

No. EPA–HQ–OAR–2008–0664. All 

documents in the docket are listed on 

the http://www.regulations.gov Web 

site. Although listed in the index, some 

information is not publicly available, 

e.g., confidential business information 

(CBI) or other information whose 

disclosure is restricted by statute. 

Certain other material, such as 

copyrighted material, is not placed on 

the Internet and will be publicly 

available only in hard copy form. 

Publicly available docket materials are 

available either electronically through 

http://www.regulations.gov or in hard 

copy at the Air Docket, EPA/DC, EPA 

West, Room 3334, 1301 Constitution 

Ave., NW., Washington, DC. This 

Docket Facility is open from 8:30 a.m. 

to 4:30 p.m., Monday through Friday, 

excluding legal holidays. The telephone 

number for the Public Reading Room is 

(202) 566–1744, and the telephone 

number for the Air Docket is (202) 566– 

1742. 

FOR FURTHER INFORMATION CONTACT: 

Margaret Sheppard, Stratospheric 

Protection Division, Office of 

Atmospheric Programs; Environmental 

Protection Agency, Mail Code 6205J, 

1200 Pennsylvania Avenue, NW., 

Washington, DC 20460; telephone 

number (202) 343–9163, fax number, 

(202) 343–2338; e-mail address at 

sheppard.margaret@epa.gov. 

Notices and rulemakings under the 

SNAP program are available on EPA’s 

Stratospheric Ozone Web site at http:// 

www.epa.gov/ozone/snap/ 

regulations.html. The full list of SNAP 

decisions in all industrial sectors is 

available at http://www.epa.gov/ozone/ 

snap. 

SUPPLEMENTARY INFORMATION: This final 

rule provides motor vehicle 

manufacturers and their suppliers an 

additional refrigerant option for motor 

vehicle air conditioning (MVAC) 

systems in new passenger cars and lightduty trucks. HFO–1234yf (2,3,3,3- 

tetrafluoroprop-1-ene), the refrigerant 

discussed in this final action, is a nonozone-depleting substance. 

Table of Contents 

I. Does this action apply to me? 

II. What abbreviations and acronyms are used 

in this action? 

III. What is EPA’s final decision for HFO– 

1234yf for motor vehicle air conditioning 

(MVAC)? 

IV. What are the final use conditions and 

why did EPA finalize these conditions? 

V. Why is EPA finding HFO–1234yf 

acceptable subject to use conditions? 

VI. What is the relationship between this 

SNAP rule and other EPA rules? 

A. Significant New Use Rule 

B. Rules Under Sections 609 and 608 of the 

Clean Air Act 

VII. What is EPA’s response to public 

comments on the proposal? 

A. Acceptability Decision 

B. Use Conditions 

C. Environmental Impacts 

D. Health and Safety Impacts 

E. Retrofit Usage 

F. Use by ‘‘Do-It-Yourselfers’’ 

G. Servicing Issues 

H. Cost, Availability, and Small Business 

Impacts 

VIII. How does the SNAP program work? 

A. What are the statutory requirements and 

authority for the SNAP program? 

B. What are EPA’s regulations 

implementing section 612? 

C. How do the regulations for the SNAP 

program work? 

D. Where can I get additional information 

about the SNAP program? 

IX. Statutory and Executive Order Reviews 

A. Executive Order 12866: Regulatory 

Planning and Review 

B. Paperwork Reduction Act 

C. Regulatory Flexibility Act 

D. Unfunded Mandates Reform Act 

E. Executive Order 13132: Federalism 

F. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

G. Executive Order 13045: Protection of 

Children From Environmental Health 

and Safety Risks 

H. Executive Order 13211: Actions That 

Significantly Affect Energy Supply, 

Distribution, or Use 

I. National Technology Transfer and 

Advancement Act 

J. Executive Order 12898: Federal Actions 

To Address Environmental Justice in 

Minority Populations and Low-Income 

Populations 

K. Congressional Review Act 

X. References 

I. Does this action apply to me? 

This final rule regulates the use of the 

chemical HFO–1234yf (2,3,3,3- 

tetrafluoroprop-1-ene, Chemical 

Abstracts Service Registry Number [CAS 

Reg. No.] 754–12–1) as a refrigerant in 

new motor vehicle air conditioning 

(MVAC) systems in new passenger cars 

and light-duty trucks. Businesses in this 

end-use that might want to use HFO– 

1234yf in new MVAC systems in the 

future include: 

• Automobile manufacturers. 

• Manufacturers of motor vehicle air 

conditioners. 

Regulated entities may include: 

TABLE 1—POTENTIALLY REGULATED ENTITIES, BY NORTH AMERICAN INDUSTRIAL CLASSIFICATION SYSTEM (NAICS) CODE

Category NAICS code Description of regulated entities 

Industry ..................................................................................... 336111 Automobile Manufacturing. 

Industry ..................................................................................... 336391 Motor Vehicle Air-Conditioning Manufacturing. 


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Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011 / Rules and Regulations 17489 

1 Designates a standard from SAE International, 

formerly the Society of Automotive Engineers. 

This table is not intended to be 

exhaustive, but rather a guide regarding 

entities likely to be regulated by this 

action. If you have any questions about 

whether this action applies to a 

particular entity, consult the person 

listed in the preceding section, FOR

FURTHER INFORMATION CONTACT. 

II. What abbreviations and acronyms 

are used in this action? 

100-yr—one-hundred year time horizon 

AEGL—Acute Exposure Guideline Level 

AIST—the National Institute for Advanced 

Industrial Science and Technology of Japan 

ASHRAE—American Society for Heating, 

Refrigerating, and Air-Conditioning 

Engineers 

ATSDR—the U.S. Agency for Toxic 

Substances and Disease Registry 

BAM—Bundesanstalt fu ̈r Materialforschung 

und-pru ̈fung (German Federal Institute for 

Materials Research and Testing) 

CAA—Clean Air Act 

CAS Reg. No.—Chemical Abstracts Service 

Registry Number 

CBI—Confidential Business Information 

CFC—chlorofluorocarbon 

CFC–12—the ozone-depleting chemical 

dichlorodifluoromethane, CAS Reg. No. 

75–71–8 

CFD—Computational Fluid Dynamics 

CFR—Code of Federal Regulations 

cm/s—centimeters per second 

CO2—carbon dioxide, CAS Reg. No. 124–38– 

9 

CRP—Cooperative Research Program 

DIN—Deutsches Institut fu ̈r Normung 

(designation for standards from the German 

Institute for Standards) 

DIY—‘‘do-it-yourself’’ 

DOT—the United States Department of 

Transportation 

EPA—the United States Environmental 

Protection Agency 

EO—Executive Order 

FMEA—Failure Mode and Effect Analysis 

FR—Federal Register 

GWP—Global Warming Potential 

HF—Hydrogen Fluoride, CAS Reg. No. 7664– 

39–3 

HI—Hazard Index 

HFC—hydrofluorocarbon 

HFC–134a—the chemical 1,1,1,2- 

tetrafluoroethane, CAS Reg. No. 811–97–2 

HFC–152a—the chemical 1,1-difluoroethane, 

CAS Reg. No. 75–37–6 

HFO—hydrofluoroolefin 

HFO–1234yf—the chemical 2,3,3,3- 

tetrafluoroprop-1-ene, CAS Reg. No. 754– 

12–1 

ISO—International Organization for 

Standardization 

JAMA—Japan Automobile Manufacturers 

Association 

JAPIA—Japan Auto Parts Industries 

Association 

LCA—Lifecycle Analysis 

LCCP—Lifecycle Climate Performance 

LFL—Lower Flammability Limit 

LOAEL—Lowest Observed Adverse Effect 

Level 

mg/L—milligram per liter 

MIR—Maximum Incremental Reactivity 

mJ—millijoule 

mm—millimeter 

MOE—Margin of Exposure 

MPa—megapascal 

MRL—Minimal Risk Level 

MVAC—Motor Vehicle Air Conditioning 

NAICS—North American Industrial 

Classification System 

ng/L—nanograms per liter 

NHTSA—the U.S. National Highway Traffic 

Safety Administration 

NOAEL—No Observed Adverse Effect Level 

NOEC—No Observed Effect Concentration 

NPRM—Notice of Proposed Rulemaking 

NTTAA—National Technology Transfer and 

Advancement Act 

ODP—Ozone Depletion Potential 

ODS—zmOzone-Depleting Substance 

OEM—Original Equipment Manufacturer 

OMB—Office of Management and Budget 

OSHA—the United States Occupational 

Safety and Health Administration 

PAG—Polyalkylene Glycol 

PMN—Pre-Manufacture Notice 

POCP—Photochemical Ozone Creation 

Potential 

POD—Point of Departure 

ppm—parts per million 

ppt—parts per trillion 

psig—pounds per square inch gauge 

R–1234yf—ASHRAE designation for 

refrigerant HFO–1234yf 

R–134a—ASHRAE designation for refrigerant 

HFC–134a 

R–152a—ASHRAE designation for refrigerant 

HFC–152a 

R–744—ASHRAE designation for refrigerant 

CO2

RCRA—the Resource Conservation and 

Recovery Act 

RFA—Regulatory Flexibility Act 

SAE—SAE International, formerly the 

Society of Automotive Engineers 

SBA—the United States Small Business 

Administration 

SIP—State Implementation Plan 

SNAP—Significant New Alternatives Policy 

SNUN—Significant New Use Notice 

SNUR—Significant New Use Rule 

SO2—sulfur dioxide, CAS Reg. No. 7446–09– 

5 

TEWI—Total Equivalent Warming Impact 

TFA—Trifluoroacetic acid, CF3COOH, also 

known as trifluoroethanoic acid, CAS Reg. 

No. 76–05–1 

TSCA—the Toxic Substances Control Act 

TWA—Time-Weighted Average 

UBA—Umweltbundesamt (German Federal 

Environment Agency) 

UF—Uncertainty Factor 

UMRA—Unfunded Mandates Reform Act 

VDA—Verband der Automobilindustrie 

(German Association for the Automobile 

Industry) 

VOC—Volatile Organic Compound 

v/v—volume to volume 

WEEL—Workplace Environmental Exposure 

Limit 

III. What is EPA’s final decision for 

HFO–1234yf for motor vehicle air 

conditioning (MVAC)? 

In this final rule, EPA is finding HFO– 

1234yf acceptable, subject to use 

conditions, as a substitute for CFC–12 in 

new MVAC systems for passenger cars 

and light-duty trucks. This 

determination does not apply to the use 

of HFO–1234yf as a conversion or 

retrofit for existing MVAC systems. In 

addition, it does not apply to the use of 

HFO–1234yf in the air conditioning or 

refrigeration systems of heavy-duty 

trucks, refrigerated transport, or off-road 

vehicles such as agricultural or 

construction equipment. 

EPA is not mandating the use of 

HFO–1234yf or any other alternative for 

MVAC systems. This final rule is adding 

HFO–1234yf to the list of acceptable 

substitutes, subject to use conditions, in 

new MVAC systems. Automobile 

manufacturers have the option of using 

any refrigerant listed as acceptable for 

this end-use, so long as they meet any 

applicable use conditions. 

Under this decision, the following 

enforceable use conditions apply when 

HFO–1234yf is used in a new MVAC 

system for passenger cars and light-duty 

trucks: 

1. HFO–1234yf MVAC systems must 

adhere to all of the safety requirements 

of SAE 1 J639 (adopted 2011), including 

requirements for a flammable refrigerant 

warning label, high-pressure compressor 

cutoff switch and pressure relief 

devices, and unique fittings. For 

connections with refrigerant containers 

of 20 lbs or greater, use fittings 

consistent with SAE J2844 (adopted 

2011). 

2. Manufacturers must conduct 

Failure Mode and Effect Analysis 

(FMEA) as provided in SAE J1739 

(adopted 2009). Manufacturers must 

keep the FMEA on file for at least three 

years from the date of creation. 

IV. What are the final use conditions 

and why did EPA finalize these 

conditions? 

Summary of the Use Conditions 

The first use condition requires that 

MVAC systems designed to use HFO– 

1234yf must meet the requirements of 

the 2011 version of the industry 

standard SAE J639, ‘‘Safety Standards 

for Motor Vehicle Refrigerant Vapor 

Compression Systems.’’ Among other 

things, this standard sets safety 

standards that include unique fittings to 

connect refrigerant containers to the 

MVAC system; a warning label 

indicating the refrigerant’s identity and 

indicating that it is a flammable 

refrigerant; and requirements for 

engineering design strategies that 

include a high-pressure compressor 

cutoff switch and pressure relief 

devices. This use condition also 

requires that fittings for refrigerant 


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17490 Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011 / Rules and Regulations 

2Assumes a fleet of approximately 250 million 

passenger vehicles and typical vehicle operation of 

500 hours per year. Sources: U.S. Census, http:// 

www.census.gov/compendia/statab/2010/tables/ 

10s1060.pdf; SAE J2766, as cited in EPA–HQ–OAR– 

2008–0664–0056.2. 

3HFC–134a is also known as 1,1,1,2- 

tetrafluoroethane or, when used as a refrigerant, 

R–134a. The Chemical Abstracts Service Registry 

Number (CAS Reg. No.) is 811–97–2. 

containers of 20 lbs or greater will be 

consistent with SAE J2844 (same fittings 

as for low-side service port in SAE 

J639). 

The second use condition requires the 

manufacturer of MVAC systems and 

vehicles (i.e., the original equipment 

manufacturer [OEM]) to conduct and 

keep records of a risk assessment and 

failure Failure Mode and Effects 

Analysis (FMEA) for at least three years 

from the date of creation. There is an 

existing industry standard, SAE J1739, 

that gives guidance on how to do this. 

It is standard industry practice to 

perform the FMEA and to keep it on file 

while the vehicle is in production and 

for several years afterwards (U.S. EPA, 

2010a). 

Reasons for Revised Use Conditions 

EPA proposed five use conditions in 

the Notice of Proposed Rulemaking 

(NPRM) (October 19, 2009; 74 FR 

53445). One use condition required 

manufacturers to meet all the safety 

requirements in the standard SAE J639, 

‘‘Safety Standards for Motor Vehicle 

Refrigerant Vapor Compression 

Systems’’ and required use of unique 

servicing fittings from that standard. 

Another use condition required 

automobile manufacturers to perform 

Failure Mode and Effect Analysis 

(FMEA) and to keep records of the 

FMEA. 

The remaining three proposed use 

conditions specifically addressed risks 

of flammability of HFO–1234yf and 

indirectly addressed risks of generating 

hydrogen fluoride (HF) from 

combustion of HFO–1234yf. For the first 

of those proposed use conditions, which 

addressed the passenger compartment, 

the concentration of HFO–1234yf was 

not to exceed the lower flammability 

limit (LFL) in the free space for more 

than 15 seconds. For the second 

proposed use condition, which 

addressed the engine compartment, the 

concentration of HFO–1234yf was not to 

exceed the LFL for any period of time. 

A third proposed use condition, which 

also addressed the engine compartment, 

would have required protective devices, 

isolation and/or ventilation techniques 

in areas where there is a potential to 

generate HFO–1234yf concentrations at 

or above 6.2% volume to volume (v/v) 

in proximity to exhaust manifold 

surfaces and hybrid or electric vehicle 

electric power sources. 

EPA based our determination of the 

appropriate use conditions to include in 

the final rule using information in the 

docket at the time of proposal, 

comments received on the proposed 

rule, and additional information we 

have received since the NPRM was 

published. We provided additional 

opportunities for comment on the 

public comments and additional 

information we received with them 

when we re-opened the comment period 

on the proposed rule (74 FR 68558, 

December 28, 2009; 75 FR 6338, 

February 9, 2010). First, SAE 

International’s Cooperative Research 

Program (hereafter called the SAE CRP) 

issued a new report on December 17, 

2009 assessing risks of HFO–1234yf and 

carbon dioxide (CO2) as refrigerants for 

MVAC. This report found that the risks 

of HFO–1234yf were low overall, and 

somewhat less than risks for another 

potential alternative refrigerant (CO2, 

also know as R–744). The December 

2009 CRP report found that the greatest 

risks from HFO–1234yf are likely to 

come from generation of HF, both from 

thermal decomposition and from 

ignition, rather than direct fire risks 

from ignition of HFO–1234yf (EPA–HQ– 

OAR–2006–0664–0056.2). (HF is a 

severe irritant to the skin, eyes, and 

respiratory system.) The SAE CRP 

estimates risks of excessive HF exposure 

at approximately 4.6 × 10¥12

occurrences per vehicle operating hour 

and risks of ignition at approximately 

9 × 10¥14 occurrences per vehicle 

operating hour. These correspond 

roughly to one occurrence in the entire 

U.S. fleet of passenger vehicles over 2 

years for HF risks and one occurrence in 

the U.S. vehicle fleet every 100 years for 

flammability risks.2 For comparison, the 

risk for excessive HF exposure is less 

than one ten-thousandth the risk of a 

highway vehicle fire and one fortieth or 

less of the risk of a fatality from 

deployment of an airbag during a 

vehicle collision (EPA–HQ–OAR–2008– 

0664–0056.2). Even these estimates may 

be conservative because they assume 

that refrigerant could be released in a 

collision severe enough to rupture the 

evaporator (under the windshield) while 

the windshield and windows would 

remain intact and would prevent 

ventilation into the passenger cabin in 

case of a collision (EPA–HQ–OAR– 

2006–0664–0056.2). 

Second, we received a number of 

public comments regarding the 

proposed use conditions. Some 

commenters claimed that the second use 

condition concerning concentrations in 

the engine compartment was infeasible 

because in the event of a leak, there 

would always be some small volume 

that would have a concentration over 

the LFL; these commenters further 

stated that exceeding the LFL would not 

necessarily create a risk of ignition, 

because one could have a leak that is 

not near a source of heat or flame (EPA– 

HQ–OAR–2006–0664–0116.2; EPA– 

HQ–OAR–2006–0664–0060). Some 

commenters stated that flammability 

was not a significant risk from use of 

HFO–1234yf, given the results of the 

SAE CRP risk assessment (December 17, 

2009). These commenters stated that the 

use conditions limiting refrigerant 

concentrations were not necessary. 

These commenters also suggested a 

number of alternative ways of phrasing 

the use conditions in order to address 

risks from HF as well as flammability. 

Most of these comments suggested 

relying on the performance of a risk 

assessment and Failure Mode and Effect 

Analysis (FMEA) consistent with SAE 

J1739 to determine appropriate 

protective strategies. Other commenters 

stated that the use conditions were not 

sufficiently protective as proposed 

because of other risks: (1) Risks due to 

generation of HF from HFO–1234yf, 

both from thermal decomposition and 

from combustion; (2) risks from direct 

toxicity of HFO–1234yf; and (3) risks 

from flammability of HFO–1234yf 

because the LFL becomes lower than 

6.2% at temperatures higher than 21 °C 

(EPA–HQ–OAR–2006–0664–0088, 

–0054, –0089, –0097 and –0057). 

After evaluating the comments and 

the additional information made 

available to the public through the reopened comment period, we have 

decided not to include the three use 

conditions that directly address 

flammability in the final rule. We 

believe these use conditions are not 

necessary to ensure that overall risks to 

human health and the environment 

from HFO–1234yf will be similar to or 

less than those of other available or 

potentially available refrigerants that 

EPA has already listed or proposed as 

acceptable for MVAC. This is because of 

the low overall levels of risk identified 

for HFO–1234yf from flammability and 

from ignition of HF (EPA–HQ–OAR– 

2008–0664–0056.2). The highest risk 

identified for HFO–1234yf is potential 

consumer exposure to HF from 

decomposition and ignition, which is of 

the same order of magnitude of risks of 

HF from the current most common 

automotive refrigerant, 

hydrofluorocarbon (HFC)–134a3 (order 

of magnitude of 10¥12 events per 

vehicle operating hour). EPA previously 


Emcdonald on DSK2BSOYB1PROD with RULES2
Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011 / Rules and Regulations 17491 

4HFC–152a is also known as 1,1-difluoroethane 

or, when used as a refrigerant, R–152a. The CAS 

Reg. No. is 75–37–6. 

5The SAE J639 standard specifies unique fittings 

for high-side and low-side service ports and the 

manufacturer of HFO–1234yf supports these 

fittings. The unique fitting for large containers for 

use in servicing by professionals (e.g., 20 or 30 lbs) 

is the same as the fitting for the low-side service 

port in SAE J639 and is also specified in SAE J2844, 

‘‘R–1234yf New Refrigerant Purity and Container 

Requirements Used in Mobile Air-Conditioning 

Systems.’’ (U.S. EPA, 2010b) 

found HFC–134a acceptable for use in 

new and retrofit MVAC systems (59 FR 

13044; March 18, 1994; and 60 FR 

31092, June 13, 1995), without use 

conditions addressing risks of HF. Since 

that time, EPA has heard of no cases 

where someone has been injured due to 

exposure to HF from decomposition of 

HFC–134a from an MVAC system, and 

a risk assessment from the SAE CRP 

found no published reports in the 

medical literature of injuries to fire 

fighters or vehicle passengers from HF 

or other decomposition products of 

HFC–134a (EPA–HQ–OAR–2008–0664– 

0008). The direct risk of flammability 

from HFO–1234yf is extremely small. 

Further, the risks of HFO–1234yf are 

comparable to or less than the risks from 

other available or potentially available 

alternatives in this end-use that EPA has 

already listed or proposed as acceptable 

(e.g., HFC–152a,4 HFC–134a, and CO2) 

(EPA–HQ–OAR–2008–0664–0086.1). 

We have concluded that the use 

conditions we are including in the final 

rule address the risks from both HF and 

flammability. Industry standard SAE 

J639 (adopted 2011) provides for a 

pressure relief device designed to 

minimize direct impingement of the 

refrigerant and oil on hot surfaces and 

for design of the refrigerant circuit and 

connections to avoid refrigerant entering 

the passenger cabin. These conditions 

will mitigate risks of HF generation and 

ignition. The pressure release device 

ensures that pressure in the system will 

not reach an unsafe level that might 

cause an uncontrolled, explosive leak of 

refrigerant, such as if the air 

conditioning system is overcharged. The 

pressure release device will reduce the 

likelihood that refrigerant leaks would 

reach hot surfaces that might lead to 

either ignition or formation of HF. 

Designing the refrigerant circuit and 

connections to avoid refrigerant entering 

the passenger cabin ensures that if there 

is a leak, the refrigerant is unlikely to 

enter the passenger cabin. Keeping 

refrigerant out of the passenger cabin 

minimizes the possibility that there 

would be sufficient levels of refrigerant 

to reach flammable concentrations or 

that HF would be formed and 

transported where passengers might be 

exposed. 

The last proposed use condition, 

requiring manufacturers to conduct and 

keep records of FMEA according to the 

standard SAE J1739, remains 

unchanged. 

The proposed use condition regarding 

conducting and keeping records of a 

Failure Mode and Effects Analysis 

according to the standard SAE J1739 

remains unchanged. We have revised 

the remaining proposed use condition 

by replacing the reference to SAE J639 

(adopted 2009) with a reference to the 

2011 version of the standard and to the 

fittings for large refrigerant containers in 

SAE J2844 (2011). This is the most 

recent version of the SAE J639 standard, 

with new provisions designed 

specifically to address use of HFO– 

1234yf. 

V. Why is EPA finding HFO–1234yf 

acceptable subject to use conditions? 

EPA is finding HFO–1234yf 

acceptable subject to use conditions 

because the use conditions are 

necessary to ensure that use of HFO– 

1234yf will not have a significantly 

greater overall impact on human health 

and the environment than other 

available or potentially available 

substitutes for CFC–12 in MVAC 

systems. Examples of other substitutes 

that EPA has already found acceptable 

subject to use conditions for use in 

MVAC include HFC–134a and HFC– 

152a. HFC–134a is the alternative most 

widely used in MVAC systems today. 

EPA has also proposed to find CO2

(R–744) acceptable subject to use 

conditions in MVAC (September 14, 

2006; 71 FR 55140). 

All alternatives listed as acceptable 

for use in MVAC systems in passenger 

cars and light-duty trucks are required 

to have unique fittings under use 

conditions issued previously under the 

SNAP Program at appendix D to subpart 

G of 40 CFR part 82 (61 FR 54040, 

October 16, 1996). Thus, all substitutes 

for use in MVAC systems in passenger 

cars and light-duty trucks are subject to 

those use conditions, at a minimum, if 

found acceptable and thus are identified 

as acceptable subject to use conditions. 

For HFO–1234yf, the unique fittings 

that must be used for MVAC systems are 

those required in the industry standard 

SAE J639 (2011). The fitting for 

refrigerant containers of 20 lbs or larger 

is specified in SAE J2844 (2011). The 

original submitter of HFO–1234yf to the 

SNAP program has provided EPA with 

a copy of and a diagram for these unique 

fittings. As described above, the fittings 

will be quick-connect fittings, different 

from those for any other refrigerant. The 

low-side service port and connections 

with containers of 20 lbs or greater will 

have an outside diameter of 14 mm 

(0.551 inches) and the high-side service 

port will have an outside diameter of 17 

mm (0.669 inches), both accurate to 

within 2 mm. The submitter has not 

provided, and the SAE standards do not 

include, unique fittings for use with 

small refrigerant containers or can taps.5

Thus, the final use conditions do not 

allow use of small containers for 

servicing MVAC systems. 

In addition to the use conditions 

regarding unique fittings, which apply 

under appendix D to subpart G of 40 

CFR part 82, EPA is requiring use 

conditions for the safe design of new 

MVAC systems using HFO–1234yf, 

consistent with standards of the 

automotive industry (e.g., SAE J1739, 

SAE J639). These use conditions are 

intended to ensure that new cars and 

light-duty trucks that have MVAC 

systems that use HFO–1234yf are 

specifically designed to minimize 

release of the refrigerant into the 

passenger cabin or onto hot surfaces that 

might result in ignition or in generation 

of HF. The industry standard SAE J1739 

gives guidelines on designing vehicles 

to address these risks. 

Cost and Availability 

EPA received initial estimates of the 

anticipated cost of HFO–1234yf from 

the manufacturer, claimed as 

confidential business information, as 

part of the initial SNAP submission 

(EPA–HQ–OAR–2008–0664–0013 and 

–0013.1). Initial publicly available 

estimates on the cost of HFO–1234yf 

were for approximately $40–60/pound 

(Weissler, 2008). The first automobile 

manufacturer to announce its 

commitment to use HFO–1234yf as a 

refrigerant has confirmed that the prices 

in its long-term purchase contracts are 

in the range that EPA considered at the 

time of proposal (Sciance, 2010). 

In May 2010, two major chemical 

manufacturers, including the original 

submitter, issued a press release, 

committing to building a ‘‘world-scale 

manufacturing facility’’ to produce 

HFO–1234yf (EPA–HQ–OAR–2008– 

0664–0128.1). The same manufacturers 

have committed to providing HFO– 

1234yf in time to meet requirements of 

a European Union directive to use only 

refrigerants with GWP less than 150 in 

new automobile designs starting in 

2011. 

Environmental Impacts 

EPA finds that HFO–1234yf does not 

pose significantly greater risk to the 

environment than the other substitutes 

that are currently or potentially 


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17492 Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011 / Rules and Regulations 

6These changes in estimates reflect ongoing 

updates to EPA’s Vintaging Model, a model that 

considers industry trends in different end-uses that 

historically have used ODS. 

7Analyzed scenarios considered HFO–1234yf 

emissions from MVAC and from both MVAC 

systems and stationary air conditioning and 

refrigeration systems. The analysis also considered 

scenarios with typical emissions from MVAC 

systems during the entire year similar to those from 

current MVAC systems using HFC–134a and 

another scenario with reduced emissions of HFO– 

1234yf of approximately 50 g/yr per vehicle, in line 

with emissions estimates in a study by Papasavva 

et al. (2009) (EPA–HQ–OAR–2008–0664–0114.1). 

Major differences between the data sources include 

assumptions of a lower leak rate (5.6% of charge vs. 

8% of charge) and a lower annualized rate of leaks 

during servicing (3.2% of charge vs. 10% of charge) 

for the Papasavva et al. paper compared to 

assumptions in EPA’s Vintaging Model (ICF 2010a). 

available. In at least one aspect, HFO– 

1234yf is significantly better for the 

environment than other alternatives 

currently found acceptable subject to 

use conditions. HFO–1234yf has a 

hundred-year time horizon (100-yr) 

global warming potential (GWP) of 4 

(Nielsen et al., 2007; Papadimitriou et 

al., 2007), compared to a GWP of 124 for 

HFC–152a, and a GWP of 1430 for HFC– 

134a (IPCC, 2007). CO2, another 

substitute currently under review in this 

end-use, has a GWP of 1, which is 

lower, but comparable to the GWP of 

HFO–1234yf. Information on the 

schedule for EPA’s final rulemaking on 

CO2 as a substitute in MVAC, RIN 2060– 

AM54, is available in EPA’s regulatory 

agenda at http://www.reginfo.gov/ 

public/do/eAgendaMain. A number of 

other refrigerant blends containing 

HFCs or HCFCs have been found 

acceptable subject to use conditions in 

MVAC that have higher GWPs in the 

range of 1000 to 2400, such as R–426A, 

R–414A, R–414B, R–416A, and R–420A. 

Further, HFO–1234yf has no ozone 

depletion potential (EPA–HQ–OAR– 

2008–0664–0013), comparable to CO2, 

HFC–152a, and HFC–134a, and has less 

risk of ozone depletion than all 

refrigerant blends containing HCFCs 

that EPA previously found acceptable 

subject to use conditions for MVAC 

systems. 

EPA also considered the aggregate 

environmental impact of all anticipated 

emissions of HFO–1234yf, both for the 

proposed rule and for this final rule. We 

performed a conservative analysis that 

assumed widespread use of HFO– 

1234yf as the primary refrigerant for 

MVAC, as well as for other refrigeration 

and air conditioning uses that were not 

included in the manufacturer’s original 

submission (ICF, 2009; ICF, 2010a,b,c,e). 

Thus, we believe that actual 

environmental impacts are likely to be 

less than those we considered, either at 

the proposal or final stage. 

Under Clean Air Act regulations (see 

40 CFR 51.100(s)) addressing the 

development of State implementation 

plans (SIPs) to attain and maintain the 

national ambient air quality standards, 

HFO–1234yf is considered a volatile 

organic compound (VOC). Available 

information indicates that HFO–1234yf 

has greater photochemical reactivity 

than HFC–134a, which is exempt from 

the definition of ‘‘VOC’’ in 40 CFR 

51.100(s). Some of the other acceptable 

substitutes in the MVAC end-use 

contain VOCs, such as R–406A, R– 

414A, R–414B, and R–426A. VOCs can 

contribute to ground-level ozone (smog) 

formation. For purposes of State plans 

to address ground-level ozone, EPA has 

exempted VOCs with negligible 

photochemical reactivity from 

regulation (40 CFR 51.100(s)). The 

manufacturer of HFO–1234yf has 

submitted a petition to EPA requesting 

that the chemical be exempted from 

regulation as a VOC, based on a claim 

that it has maximum incremental 

reactivity comparable to that of ethane 

(EPA–HQ–OAR–2008–0664–0116.1). 

Separate from this action, EPA is 

reviewing that request and plans to 

issue a proposed rule to address it. 

Information on the schedule for EPA’s 

proposed rulemaking for exemption 

from regulation as a VOC for HFO– 

1234yf, RIN 2060–AQ38, is available in 

EPA’s regulatory agenda at http:// 

www.reginfo.gov/public/do/ 

eAgendaMain. 

Regardless of whether EPA 

determines to exempt HFO–1234yf from 

regulation as a VOC for State planning 

purposes, other analyses available in the 

docket during the public comment 

period indicated that the additional 

contribution to ground-level ozone due 

to a widespread switch to HFO–1234yf 

is likely to be around 0.01% or less of 

all VOC emissions, based on the 

formation of reactive breakdown 

products such as OH¥ (Luecken et al., 

2009). Since issuing the NPRM, we 

performed an additional analysis that 

finds a worst-case increase in the Los 

Angeles region of 0.00080 ppm, or a 

contribution of only 0.1% of the 1997 8- 

hour standard for ground-level ozone of 

0.08 ppm (ICF, 2010b). Our initial 

analysis at the proposal stage had 

estimated a maximum increase in ozone 

of 1.4 to 4.0% of the standard in the 

same region (ICF, 2009). The major 

difference between the 2009 and the 

2010 versions of this analysis involved 

modeling of atmospheric chemistry. The 

2010 study was based on the kinetics 

and decomposition products predicted 

for HFO–1234yf, rather than using the 

oxidation of sulfur dioxide (SO2) as a 

proxy for decomposition of HFO–1234yf 

as was done in the 2009 study. The 2010 

analysis used updated baseline emission 

estimates that were 1.5% higher to 5.8% 

lower than those in the 2009 analysis,6

depending on the year analyzed (ICF, 

2010e). We also evaluated 

environmental impacts based on 

alternative emissions estimates from a 

peer-reviewed journal article provided 

during the public comment period 

(Papasavva et al., 2009); 7 these values 

ranged from 26.3% to 51.1% lower than 

EPA’s estimates in the 2009 analysis 

(ICF, 2009; ICF, 2010c). 

Another potential environmental 

impact of HFO–1234yf is its 

atmospheric decomposition to 

trifluoroacetic acid (TFA, CF3COOH). 

TFA is a strong acid that may 

accumulate on soil, on plants, and in 

aquatic ecosystems over time and that 

may have the potential to adversely 

impact plants, animals, and ecosystems. 

Other fluorinated compounds also 

decompose into TFA, including HFC– 

134a. However, the amount of TFA 

produced from HFO–1234yf in MVAC is 

estimated to be at least double that of 

current natural and artificial sources of 

TFA in rainfall (Luecken et al., 2009). 

An initial analysis performed for EPA at 

the proposal stage found that, with 

highly conservative emission estimates, 

TFA concentrations in rainwater could 

be as high as 1.8 mg/L for the maximum 

monthly concentration for the Los 

Angeles area and would be no higher 

than 0.23 mg/L on an annual basis, 

compared to a no observed adverse 

effect concentration of 1 mg/L for the 

most sensitive plant species (ICF, 2009). 

This analysis concluded, ‘‘Projected 

levels of TFA in rainwater should not 

result in a significant risk of 

ecotoxicity.’’ A more recent analysis by 

Luecken et al (2009) that became 

available during the initial public 

comment period reached the conclusion 

that emissions of HFO–1234yf from 

MVAC could produce TFA 

concentrations in rainwater of 1/800th 

to 1/80th the no-observed adverse effect 

level (NOAEL) for the most sensitive 

algae species expected (Luecken et al., 

2009). The conclusions in the Luecken 

study are supported by additional 

analyses that have become available 

since we issued the proposed rule. A 

study from the National Institute of 

Advanced Industrial Science and 

Technology (AIST) in Japan, which 

became available during the re-opened 

comment period, estimated that 

concentrations of TFA in surface water 

would be approximately twice the level 

in rainwater (Kajihara et al., 2010). This 

study found that this higher level in 

surface water would be roughly 1/80th 


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Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011 / Rules and Regulations 17493 

8On September 30, 2010, we received a final 

report from the German Federal Environment 

Agency (UBA) with additional information from 

testing of HFO–1234yf’s potential for flammability 

and for generating hydrogen fluoride. Although this 

comment was received too late in the rulemaking 

process for us to analyze it in depth, our 

preliminary review found that the procedures they 

used contain many unrealistic provisions that are 

not relevant to our decision and in some tests did 

not provide proper controls (e.g., lacking a 

comparison to HFC–134a under the same 

conditions). Concerning flammability risk, the 

results do not vary significantly from those we are 

relying on for the final rule. Thus, our preliminary 

review of the UBA test procedures and results does 

not suggest that we should re-evaluate our decision 

to find HFO–1234yf acceptable subject to use 

conditions. 

9This was based on a NOAEL of 4000 ppm from 

the study, ‘‘An Inhalation Prenatal Developmental 

Toxicity Study of HFO–1234yf (2,3,3,3- 

Tetrafluoropropene) in Rabbits,’’ EPA–HQ–OAR– 

2008–0664–0041. We used a factor of 1.9 to account 

for differences in blood concentrations between 

animals and humans, and a margin of exposure or 

collective uncertainty factor of 30. Uncertainty 

factors of 3 were assigned for animal to human 

extrapolation, and 10 for variability within the 

human population. The long-term workplace 

exposure limit was calculated as follows: 4000 ppm 

(animal exposure) × 1.9 (ratio of estimated human 

exposure/animal exposure) × 1⁄3 (UF for animal to 

human extrapolation) × 1⁄10 (UF for variability 

within the human population) exposure) = 250 

ppm. This value was compared against 8-hour 

average concentrations. See EPA–HQ–OAR–2008– 

0664–0036 and EPA–HQ–OAR–2008–0664–0038. 

10This was based on a NOAEL of 51,690 ppm 

from the study, ‘‘Sub-acute (2-week) Inhalation 

Toxicity Study with HFO–1234yf in rats,’’ EPA– 

HQ–OAR–2008–0664–0020 through-0020.4, a factor 

of 1.9 to account for differences in blood 

concentrations between animals and humans and a 

margin of exposure or collective uncertainty factor 

of 30. Uncertainty factors of 3 were assigned for 

animal to human extrapolation, and 10 for 

variability within the human population. The shortterm workplace exposure value was calculated as 

follows: 51,690 ppm (animal exposure) × 1.9 (ratio 

of estimated human exposure/animal exposure) = 

98,211 ppm This value was then divided by the 

expected exposure in each scenario, and compared 

against the target margin of exposure of 30. See 

EPA–HQ–OAR–2008–0664–0036 and EPA–HQ– 

OAR–2008–0664–0038. 

11For comparison, the SAE CRP used exposure 

limits of 500 ppm over 8 hours and 115,000 ppm 

over 30 minutes to evaluate risks for these same 

time periods. These are based on the 8-hr 

Workplace Environmental Exposure Limit (WEEL) 

for HFO–1234yf and for short-term exposure, 

assuming a NOAEL of approximately 405,800 ppm 

from the study, ‘‘Acute (4-hour) inhalation toxicity 

study with HFO–1234yf in rats.’’ Note that EPA 

disagrees with the finding that the acute inhalation 

toxicity study found a NOAEL. We consider this 

study to show adverse effects at all levels because 

of the presence of grey discoloration in the lungs 

of the test animals. In order to ensure sufficient 

protection, EPA’s risk assessment used a NOAEL 

from a subacute study instead of a LOAEL from an 

acute study. 

the NOAEL for the most sensitive algae 

species, even with assumptions of high 

emissions levels (i.e., assuming that all 

types of refrigeration and AC equipment 

currently using HFCs or HCFCs, not just 

MVAC systems, would use HFO– 

1234yf). Kajihara et al. (2010) evaluated 

scenarios specific to Japan, with 

emissions of approximately 15,172 ton/ 

yr in 2050, compared to a maximum of 

64,324 metric tons/yr in 2050 in ICF, 

2009 or a maximum of 24,715 metric 

tons/yr in 2017 in Luecken et al (2009). 

All three studies noted the potential for 

accumulation in closed aquatic systems. 

As we developed the proposed rule, 

the data we relied on indicated that in 

the worst case, the highest monthly TFA 

concentrations in the area with the 

highest expected emissions, the Los 

Angeles area, could exceed the no 

observed adverse effect concentration 

for the most sensitive plant species, but 

annual values would never exceed that 

value. Further, TFA concentrations 

would never approach levels of concern 

for aquatic animals (ICF, 2009). In a 

more recent analysis, ICF (2010a, b, c, 

e) performed modeling for EPA using 

the kinetics and decomposition 

products predicted specifically for 

HFO–1234yf and considered revised 

emission estimates that were slightly 

lower than in a 2009 analysis (ICF, 

2009). The revised analysis found a 

maximum projected concentration of 

TFA in rainwater of approximately 

1,700 ng/L, roughly one-thousandth of 

the estimate from our 2009 analysis 

(ICF, 2010b). This maximum 

concentration is roughly 34% higher 

than the 1,264 ng/L reported by Luecken 

et al. (2009), reflecting the higher 

emission estimates we used (ICF, 

2010b). A maximum concentration of 

1700 ng/L corresponds to roughly 1/ 

600th of the NOAEL for the most 

sensitive algae species—thus, it is not a 

level of concern. We find these 

additional analyses confirm that the 

projected maximum TFA concentration 

in rainwater and in surface waters 

should not result in a significant risk of 

aquatic toxicity, consistent with our 

original proposal. 

Human Health and Safety Impacts 

Occupational risks could occur during 

the manufacture of the refrigerant, 

initial installation of the refrigerant into 

the MVAC system at the car assembly 

plant, servicing of the MVAC system, or 

final disposition of the MVAC system 

(i.e., recycling or disposal). Consumer 

risks could occur to drivers or riders in 

the passenger compartment. Risks of 

exposure to consumers could also occur 

if they purchase HFO–1234yf and 

attempt to install or service the MVAC 

system without proper training or use of 

refrigerant recovery equipment. In 

addition, members of the general public, 

consumers, and first-responders could 

face risks in the case of a vehicle 

accident that is severe enough to release 

the refrigerant. 

To evaluate these potential human 

health and safety impacts, we 

considered EPA’s own risk assessments 

(EPA–HQ–OAR–2008–0664–0036 and 

–0038), as well as detailed risk 

assessments with fault-tree analysis 

from the SAE CRP for HFO–1234yf and 

CO2 (EPA–HQ–OAR–2008–0664–0008 

and –0056.2), and scientific data 

provided in public comments on the 

topics of health and safety risks.8 Health 

and safety risks that we evaluated 

included direct toxicity of HFO–1234yf, 

both long-term and short-term; toxicity 

of HF formed through thermal 

decomposition or combustion of HFO– 

1234yf; and flammability of HFO– 

1234yf. 

Occupational Risks 

For long-term occupational exposure 

to HFO–1234yf, EPA compared worker 

exposures to a workplace exposure limit 

of 250 ppm 9 over an 8-hour timeweighted average. For short-term 

occupational exposure to HFO–1234yf, 

we compared worker exposure to an 

acute exposure limit of 98,211 ppm, 

divided by a margin of exposure of 30, 

for a value of 3270 ppm over 30 

minutes.10,11

Section 609 of the Clean Air Act 

requires technicians servicing MVAC 

systems for consideration (e.g., receiving 

money, credit, or services in exchange 

for their work) to use approved 

refrigerant recycling equipment 

properly and to have proper training 

and certification. Therefore, we expect 

that professional technicians have the 

proper equipment and knowledge to 

minimize their risks due to exposure to 

refrigerant from an MVAC system. Thus, 

we found that worker exposure would 

be low. Further, EPA intends to pursue 

a future rulemaking under Section 609 

of the CAA to apply also to HFO–1234yf 

(e.g., servicing practices, certification 

requirements for recovery and recycling 

equipment intended for use with 

MVACs using HFO–1234yf, any 

potential changes to the rules for 

training and testing technicians, and 

recordkeeping requirements for service 

facilities and for refrigerant retailers). If 

workers service MVAC systems using 

certified refrigerant recovery equipment 

after receiving training and testing, 

exposure levels to HFO–1234yf are 

estimated to be on the order of 4 to 8.5 

ppm on an 8-hour time-weighted 

average (as compared with a 250 ppm 

workplace exposure limit) and 122 ppm 

on a 30-minute average (as compared 

with a short-term exposure level of 

98,211 ppm/[margin of exposure of 30] 

or 3270 ppm). (EPA–HQ–OAR–2008– 

0664–0036; EPA–HQ–OAR–2008–0664– 


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17494 Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011 / Rules and Regulations 

0038). We also analyzed exposure levels 

during manufacture and final 

disposition at vehicle end-of-life, and 

found that they would be no higher than 

28 ppm on a 15-minute average or 8.5 

ppm on an 8-hour time-weighted 

average (EPA–HQ–OAR–2008–0664– 

0038). Therefore, the manufacture, use, 

and disposal or recycling of HFO– 

1234yf are not expected to present a 

toxicity risk to workers. 

We did not analyze the risk of 

generation of HF in the workplace. In its 

December 17, 2009 Risk Assessment for 

Alternative Refrigerants HFO–1234yf 

and R–744 (CO2), the SAE CRP 

indicated that ‘‘service technicians will 

be knowledgeable about the potential 

for HF generation and will immediately 

move away from the area when they 

perceive the irritancy of HF prior to 

being exposed above a health-based 

limit’’ (EPA–HQ–OAR–2008–0664– 

0056.2). Since there is a similar 

potential to form HF from other MVAC 

refrigerants that have been used for 

years, such as CFC–12 or HFC–134a, it 

is reasonable to assume that service 

technicians, recyclers, and disposers 

will handle HFO–1234yf similarly and 

that use of HFO–1234yf does not pose 

a significantly greater risk in the 

workplace with regard to HF generation 

than the use of those other refrigerants. 

In that same report, the SAE CRP also 

discussed qualitatively the risks for 

emergency responders, such as 

firefighters or ambulance workers that 

respond in case of a vehicle fire or 

collision. With regard to risk of fire, the 

CRP report stated that ‘‘Due to the low 

burning velocity of HFO–1234yf, 

ignition of the refrigerant will not 

contribute substantially to a pre-existing 

fire’’ (EPA–HQ–OAR–2008–0664– 

0056.2). EPA considers this reasonable, 

given a burning velocity for HFO– 

1234yf of only 1.5 cm/s. This is more 

than an order of magnitude less than the 

burning velocity of gasoline, which is 

approximately 42 cm/s (Ceviz and 

Yuksel, 2005). Concerning first 

responder exposure to HF, the SAE CRP 

stated, ‘‘Professional first responders 

also have training in chemical hazards 

and possess appropriate gear which will 

prevent them from receiving HF 

exposures above health-based limits’’ 

(EPA–HQ–OAR–2008–0664–0056.2). 

We agree with this assessment. Other 

MVAC refrigerants containing fluorine 

such as CFC–12, which was historically 

used, and HFC–134a, which is the 

predominant refrigerant currently in 

use, also can produce HF due to thermal 

decomposition or combustion, and 

smoke and other toxic chemicals are 

likely to be present in case of an 

automotive fire (CRP, 2008). Therefore, 

it is reasonable to expect that first 

responders are prepared for the 

presence of HF and other toxic 

chemicals when approaching a burning 

vehicle and that they will wear 

appropriate personal protective 

equipment. 

EPA’s risk screen for HFO–1234yf 

evaluated flammability risks, including 

occupational risks. Modeling of 

concentrations of HFO–1234yf in 

workplace situations such as at 

equipment manufacture and during 

disposal or recycling at vehicle end-oflife found short-term, 15-minute 

concentrations of 28 ppm or less—far 

below the lower flammability limit 

(LFL) of 6.2% by volume (62,000 ppm) 

(EPA–HQ–OAR–2008–0664–0038). The 

SAE CRP’s risk assessments evaluated 

flammability risks by comparing 

concentrations of HFO–1234yf with the 

LFL of 6.2%. The SAE CRP conducted 

Computational Fluid Dynamics (CFD) 

modeling of exposure levels in case of 

a leak in a system in a service shop. The 

SAE CRP’s earlier February 26, 2008 

risk assessment found that a leaked 

concentration of HFO–1234yf exceeded 

the LFL only in the most conservative 

simulation, with the largest refrigerant 

leak and with all air being recirculated 

within the passenger cabin (EPA–HQ– 

OAR–2008–0664–0010). Updated CFD 

modeling performed for the December, 

2010 SAE CRP risk assessment found 

that concentrations of HFO–1234yf 

sometimes exceeded the LFL, but only 

within ten centimeters of the leak or less 

(EPA–HQ–OAR–2008–0664–0056.2). 

The risk assessment found the risk of 

this occupational exposure scenario to 

be on the order of 10¥26 cases per 

working hour. We note that HFO– 

1234yf is less flammable and results in 

a less energetic flame than a number of 

fluids that motor vehicle service 

technicians and recyclers or disposers 

deal with on a regular basis, such as oil, 

anti-freeze, transmission fluid, and 

gasoline. HFO–1234yf is also less 

flammable than HFC–152a, a substitute 

that we have already found acceptable 

for new MVAC systems subject to use 

conditions. Thus, EPA finds that the 

risks of flammability in the workplace 

from HFO–1234yf are similar to or 

lower than the risk posed by currently 

available substitutes when the use 

conditions are met. 

Consumer Exposure 

EPA’s review of consumer risks from 

toxicity of HFO–1234yf indicated that 

potential consumer (passenger) 

exposure from a refrigerant leak into the 

passenger compartment of a vehicle is 

not expected to present an unreasonable 

risk (EPA–HQ–OAR–2008–0664–0036, 

EPA–HQ–OAR–2008–0664–0038). 

However, consumer exposure from 

filling, servicing, or maintaining MVAC 

systems may cause exposures at high 

enough concentrations to warrant 

concern. Specifically, this risk may be 

due to a lack of professional training 

and due to refrigerant handling or 

containment without the use of 

refrigerant recovery equipment certified 

in accordance with the regulations 

promulgated under CAA Section 609 

and codified at subpart B of 40 CFR part 

82. Consumer filling, servicing, or 

maintaining of MVAC systems may 

cause exposures at high enough 

concentrations to warrant concern 

(EPA–HQ–OAR–2008–0664–0036). 

However, this rule does not specifically 

allow for use of HFO–1234yf in 

consumer filling, servicing, or 

maintenance of MVAC systems. The 

manufacturer’s submission specifically 

addressed HFO–1234yf as a refrigerant 

for use by OEMs and by professional 

technicians (EPA–HQ–OAR–2008– 

0664–0013.1). 

The use conditions in this final rule 

provide for unique service fittings 

relevant to OEMs and to professional 

technicians (i.e., unique fittings for the 

high-pressure side and for the lowpressure side of the MVAC system and 

unique fittings for large cylinders of 20 

lb or more). EPA would require 

additional information on consumer risk 

and a set of unique fittings from the 

refrigerant manufacturer for use with 

small cans or containers of HFO–1234yf 

before we would be able to issue a 

revised rule that allows for consumer 

filling, servicing, or maintenance of 

MVAC systems with HFO–1234yf. 

EPA has issued a significant new use 

rule (SNUR) under the authority of 

TSCA (October 27, 2010; 75 FR 65987). 

Under 40 CFR part 721, EPA may issue 

a SNUR where the Agency determines 

that activities other than those described 

in the premanufacture notice may result 

in significant changes in human 

exposures or environmental release 

levels and that concern exists about the 

substance’s health or environmental 

effects. Manufacturers, importers and 

processors of substances subject to a 

SNUR must notify EPA at least 90 days 

before beginning any designated 

significant new use through a significant 

new use notice (SNUN). EPA has 90 

days from the date of submission of a 

SNUN to decide whether the new use 

‘‘may present an unreasonable risk’’ to 

human health or the environment. If the 

Agency does not determine that the new 

use ‘‘may present an unreasonable risk,’’ 

the submitter would be allowed to 

engage in the use, with or without 

certain restrictions. The significant new 


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Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011 / Rules and Regulations 17495 

12EPA has issued lists of approved unique fittings 

for refrigerants in MVAC (see http://www.epa.gov/ 

ozone/snap/refrigerants/fittlist.html). These have 

been issued for the high-side service port, low-side 

service port, 30-lb cylinders (that is, the most 

typical size container for use in professional 

servicing), and small cans (containers typically 

used by consumers). The label ‘‘30-lb cylinders’’ is 

not intended to restrict the existence of other 

container sizes that professional service technicians 

might use (e.g., 50 lb, 20 lb, 10 lb). 

13The AEGL–2 is defined as ‘‘the airborne 

concentration of a substance * * * above which it 

is predicted that the general population, including 

susceptible individuals could experience 

irreversible or other serious, long lasting adverse 

effects or an impaired ability to escape.’’ http:// 

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

14 If we assume 250 million passenger vehicles in 

the U.S. and typical driving times of 500 hours per 

year per vehicle, a risk of 4.6 × 10¥12 per operating 

hour equates roughly to one event every 2 years for 

all drivers in the entire U.S. 

uses identified in the SNUR for HFO– 

1234yf are: (1) Use other than as a 

refrigerant in motor vehicle air 

conditioning systems in new passenger 

cars and vehicles; (2) commercial use 

other than in new passenger cars and 

vehicles in which the charging of motor 

vehicle air conditioning systems with 

HFO–1234yf was done by the motor 

vehicle OEM; and (3) distribution in 

commerce of products intended for use 

by a consumer for the purposes of 

servicing, maintenance and disposal 

involving HFO–1234yf. 

Under existing regulations in 

appendix D to subpart G of 40 CFR part 

82, ‘‘A refrigerant may only be used with 

the fittings and can taps specifically 

intended for that refrigerant and 

designed by the manufacturer of the 

refrigerant. Using a refrigerant with a 

fitting designed by anyone else, even if 

it is different from fittings used with 

other refrigerants, is a violation of this 

use condition.’’ The manufacturer and 

submitter for HFO–1234yf has provided 

unique fittings for the high-pressure 

side and for the low-pressure side of the 

MVAC system and for large cylinders 

for professional use (typically 20 lb or 

more 12). Therefore, until the 

manufacturer provides unique fittings to 

EPA’s SNAP Program for use with can 

taps or other small containers for 

consumer use and until EPA publishes 

a final rule identifying such unique 

fittings, it would be a violation of the 

use condition in appendix D to use 

HFO–1234yf in small cans or containers 

for MVAC. Before issuing a rule 

allowing use of HFO–1234yf with 

fittings for small cans or containers for 

MVAC, we would first need to conclude 

through either review under TSCA or 

under the SNAP program that use of 

these smaller canisters would not pose 

an unreasonable risk to consumers. 

In our review of consumer risks from 

HFO–1234yf, we considered 

information concerning consumer 

exposure to HF from thermal 

decomposition or combustion of HFO– 

1234yf. EPA’s analysis at the time of the 

proposed rule focused on the 

flammability risk to consumers, which 

at the time we believed to be a 

significant risk in its own right, as well 

as a way to prevent consumer exposure 

to HF from combustion of HFO–1234yf. 

However, in preparing our proposal, we 

had available and did consider the SAE 

CRP’s 2008 evaluation of scenarios that 

might cause consumer or occupational 

exposure to HF (CRP, 2008). This report 

stated: 

Decomposition of HFO–1234yf in a fire 

scenario might, in theory, pose a significant 

acute health risk to passengers or firemen. 

But in the event of a fire, other toxic 

chemicals will be produced by combustion of 

other automotive components and thus 

decomposition of the refrigerant may 

increase the risk for fire fighters and would 

not introduce an entirely new type of hazard. 

It is also anticipated that only a small portion 

of the refrigerant charge will be converted to 

these decomposition products. In U.S. EPA’s 

assessment of risk of R–152a and CO2 (R– 

744), the agency cited a study by 

Southwestern Laboratories which indicated 

that a 100% R–134a atmosphere only 

produced an HF concentration of 10 ppm 

when passed through a tube heated to 1,000 

°F (Blackwell et al., 2006). A search of the 

medical literature also did not reveal any 

published reports of injuries to fire fighters 

or vehicle passengers resulting from 

exposures to COF2 or HF produced in fires 

involving refrigerants. (EPA–HQ–OAR–2008– 

0664–0008, p. 67) 

After the SAE CRP’s 2008 evaluation, 

SAE CRP members conducted tests to 

measure HF concentrations and to 

identify factors that were most likely to 

lead to HF formation (EPA–HQ–OAR– 

2008–0664–0056.2). One test on HF 

concentrations inside a car cabin found 

maximum concentrations were in the 

range of 0 to 35 ppm in trials both with 

HFO–1234yf and with HFC–134a, with 

concentrations dropping to 10 ppm or 

less after 10 minutes. In a second test of 

HF generated in the engine 

compartment, HF concentrations from 

thermal decomposition of HFO–1234yf 

reached as high as 120 ppm in the 

engine compartment in the worst case, 

with interior passenger cabin values of 

40 to 80 ppm. Under the same extreme 

conditions (flash ignition, temperature 

of 700 °C, closed hood), HF 

concentrations from thermal 

decomposition of HFC–134a reached 

36.1 ppm in the engine compartment 

with interior passenger cabin values of 

2 to 8 ppm. The other trials with less 

extreme conditions found HF 

concentrations from HFO–1234yf in the 

engine compartment of 0 to 8 ppm. 

The SAE CRP selected an Acute 

Exposure Guideline Limit (AEGL)¥2 of 

95 ppm over 10 minutes as its criterion 

for determining toxicity risk from HF.13

Thus, even assuming levels inside a 

passenger compartment reached the 

highest level that occurred during the 

tests—80 ppm—a passenger inside a 

vehicle would at worst experience 

discomfort and irritation, rather than 

any permanent effects. HF levels that 

could result in similar effects were also 

observed for HFC–134a. The SAE CRP 

concluded that the probability of such a 

worst-case event is on the order of 10¥12

occurrences per operating hour 14 (EPA– 

HQ–OAR–2008–0664–0056.2). This 

level of risk is similar to the current 

level of risk of HF generated from HFC– 

134a (EPA–HQ–OAR–2008–0664– 

0086.1). To date, EPA is unaware of any 

reports of consumers affected by HF 

generated by HFC–134a, which has been 

used in automobile MVAC systems 

across the industry since 1993. Thus, we 

do not expect there will be a significant 

risk of HF exposure to consumers from 

HFO–1234yf. 

Depending on the charge size of an 

HFO–1234yf MVAC system, which may 

range from as little as 400 grams to as 

much as 1600 grams (ICF, 2008), it is 

possible in a worst case scenario to 

reach a flammable concentration of 

HFO–1234yf inside the passenger 

compartment. This could occur in the 

case of a collision that ruptures the 

evaporator in the absence of a switch or 

other engineering mitigation device to 

prevent flow of high concentrations of 

the refrigerant into the passenger 

compartment, provided that the 

windows and windshield remain intact. 

As stated in the SAE CRP, ignition of 

the refrigerant once in the passenger 

cabin is unlikely (probability on the 

order of 10¥14 occurrences per 

operating hour) because the only causes 

of ignition within the passenger cabin 

with sufficient energy to ignite the 

refrigerant would be use of a butane 

lighter (EPA–OAR–2008–0664–0056.2). 

If a passenger were in a collision, or in 

an emergency situation, it is unlikely 

that they would choose to operate a 

butane lighter in the passenger cabin. 

Additionally, it is unlikely ignition 

would occur from a flame from another 

part of the vehicle because automobiles 

are constructed to seal off the passenger 

compartment with a firewall. If a 

collision breached the passenger 

compartment such that a flame from 

another part of the vehicle could reach 

it, that breach would also create 

ventilation that would lower the 

refrigerant concentration below the 


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15Service for consideration means receiving 

something of worth or value to perform service, 

whether in money, credit, goods, or services. 

16EPA previously reviewed two hydrocarbon 

blends for use in MVAC and found them 

unacceptable, stating ‘‘Flammability is a serious 

concern. Data have not been submitted to 

demonstrate that [the hydrocarbon blend] can be 

used safely in this end-use.’’ Appendixes A and B 

to subpart G of 40 CFR part 82. 

lower flammability limit. Similarly, if 

either a window or the windshield were 

broken in the collision, the ventilation 

created would lower the refrigerant 

concentration below the lower 

flammability limit. Therefore, EPA finds 

that flammability risks of HFO–1234yf 

to passengers inside a vehicle will be 

low. Further, these risks are likely to be 

less than those from HFC–152a, another 

flammable refrigerant that EPA has 

previously found acceptable subject to 

use conditions, because HFC–152a has a 

lower LFL and a lower minimum 

ignition energy than HFO–1234yf (EPA– 

HQ–OAR–2008–0664–0008, –0013.4, 

–0056.2). 

Overall Conclusion 

EPA finds that the use of HFO–1234yf 

in new passenger vehicle and light-duty 

truck MVAC systems, subject to the use 

conditions being adopted in the final 

rule, does not present a significantly 

greater risk to human health and the 

environment compared to the currentlyapproved MVAC alternatives or as 

compared to CO2, which has been 

proposed for approval in this end-use. 

VI. What is the relationship between 

this SNAP rule and other EPA rules? 

A. Significant New Use Rule 

Under the Toxics Substances Control 

Act, EPA has issued a Significant New 

Use Rule (75 FR 65987; October 27, 

2010) for 1-propene, 2,3,3,3- 

tetrafluoro-, which is also known as 

HFO–1234yf. This rule requires persons 

who intend to manufacture, import, or 

process HFO–1234yf for a use that is 

designated as a significant new use in 

the final SNUR to submit a SNUN at 

least 90 days before such activity may 

occur. EPA has 90 days from the date of 

submission of a SNUN to decide 

whether the new use ‘‘may present an 

unreasonable risk’’ to human health or 

the environment. If the Agency does not 

determine that the new use ‘‘may 

present an unreasonable risk,’’ the 

submitter would be allowed to engage in 

the use, with or without certain 

restrictions. The significant new uses 

identified in the final SNUR and subject 

to the SNUN requirement are: Use other 

than as a refrigerant in motor vehicle air 

conditioning systems in new passenger 

cars and vehicles; commercial use other 

than in new passenger cars or vehicles 

and in which the charging of motor 

vehicle air conditioning systems with 

HFO–1234yf was done by the motor 

vehicle OEM; and distribution in 

commerce of products intended for use 

by a consumer for the purpose of 

servicing, maintenance and disposal 

involving HFO–1234yf. The health 

concerns expressed in the final SNUR 

are based primarily on potential 

inhalation exposures to consumers 

during ‘‘do-it-yourself’’ servicing, as well 

as a number of other relevant factors. 

B. Rules Under Sections 609 and 608 of 

the Clean Air Act 

Section 609 of the CAA establishes 

standards and requirements regarding 

servicing of MVAC systems. These 

requirements include training and 

certification of any person that services 

MVAC systems for consideration,15 as 

well as standards for certification of 

equipment for refrigerant recovery and 

recycling. EPA has issued regulations 

interpreting this statutory requirement 

and those regulations are codified at 

subpart B of 40 CFR part 82. The 

statutory and regulatory provisions 

regarding MVAC servicing apply to any 

refrigerant alternative and are not 

limited to refrigerants that are also ODS. 

This final SNAP rule addresses the 

conditions for safe use of HFO–1234yf 

in new MVAC systems. Thus, the 

requirements in this rule apply 

primarily to OEMs, except for specific 

requirements for service fittings unique 

to HFO–1234yf. MVAC end-of-life 

disposal and recycling specifications are 

covered under section 608 of the CAA 

and our regulations issued under that 

section of the Act. 

VII. What is EPA’s response to public 

comments on the proposal? 

This section of the preamble 

summarizes the major comments 

received on the October 19, 2009 

proposed rule, and EPA’s responses to 

those comments. Additional comments 

are addressed in a response to 

comments document in docket EPA– 

HQ–OAR–2008–0664. 

A. Acceptability Decision 

Comment: Several commenters 

supported EPA’s proposal to find HFO– 

1234yf an acceptable substitute for 

CFC–12 in MVACs. These commenters 

stated that available information 

indicates that HFO–1234yf will not pose 

significant health risks or environmental 

concerns under foreseeable use and leak 

conditions and that it has a strong 

potential to reduce greenhouse gas 

emissions from motor vehicles. Also, 

these commenters declared that HFO– 

1234yf’s risks were similar to or less 

than those of other available 

alternatives, such as HFC–134a, HFC– 

152a, and CO2. A commenter referenced 

the work of the SAE CRP, which 

concluded that HFO–1234yf can be used 

safely through established industry 

practices for vehicle design, 

engineering, manufacturing, and 

service. 

Other commenters opposed finding 

HFO–1234yf acceptable or stated that 

there was insufficient information to 

support a conclusion. These 

commenters stated that the risks of 

HFO–1234yf were greater than those of 

other available alternatives, such as 

HFC–134a, CO2, and hydrocarbons. 

Response: For the reasons provided in 

more detail above, EPA has determined 

that HFO–1234yf, if used in accordance 

with the adopted use conditions, can be 

used safely in MVAC systems in new 

passenger vehicles and light-duty 

trucks. The use conditions established 

by this final rule ensure that the overall 

risks to human health and the 

environment are comparable to or less 

than those of other available or 

potentially available substitutes, such as 

HFC–134a, HFC–152a, or CO2. EPA did 

not compare the risks to those posed by 

hydrocarbons since we have not yet 

received adequate information for 

hydrocarbons that would allow us to 

make such a comparison for use in 

MVAC.16

Comment: Some commenters 

suggested that EPA should consider 

other substitutes for CFC–12 in MVAC, 

such as CO2 or hydrocarbons. An 

organization representing the 

automotive industry stated that the risks 

from using CO2 in MVAC systems are 

below the probability of other adverse 

events which society considers 

acceptable and are roughly 1.5 orders of 

magnitude greater than the risks from 

using HFO–1234yf. 

Response: This rule only concerns 

EPA’s decision on the use of HFO– 

1234yf in new passenger vehicles and 

light-duty trucks. In a separate action, 

EPA has proposed to find CO2

acceptable subject to use conditions as 

a substitute for CFC–12 in MVAC 

systems for new motor vehicles 

(September 16, 2006; 71 FR 55140). 

Information on the schedule for EPA’s 

final rulemaking on CO2 as a substitute 

in MVAC, RIN 2060–AM54, is available 

in EPA’s regulatory agenda at http:// 

www.reginfo.gov/public/do/ 

eAgendaMain. We currently have 

inadequate information on 

hydrocarbons to consider adding them 

to the list of substitutes for MVAC. We 


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will review additional substitutes if they 

are submitted with complete and 

adequate data to allow an evaluation of 

whether such substitutes may be used 

safely within the meaning of section 612 

of the CAA as compared with other 

existing or potential substitutes in the 

MVAC end-use. 

B. Use Conditions 

Comment: Several commenters stated 

that the proposed use conditions 

limiting concentrations of HFO–1234yf 

below the lower flammability limit are 

overly stringent or even impossible to 

meet and are not needed for safe usage. 

Some automobile manufacturers 

suggested relying upon established 

standards and practices, such as SAE 

protocols and standards, instead of use 

conditions. Some commenters suggested 

alternative language for use conditions. 

Other commenters expressed concern 

that the proposed use conditions 

limiting concentrations of HFO–1234yf 

would preclude the use of HFO–1234yf 

by any vehicle that is not initially 

designed to use this refrigerant. 

Response: As described above, EPA 

agrees that the use conditions, as 

proposed, require modification. In this 

final rule, we have removed the first 

three proposed use conditions, which 

required design to keep refrigerant 

concentrations below the LFL. See 

section IV of the preamble, ‘‘What are 

the final use conditions and why did 

EPA finalize these conditions?’’ for our 

basis. With respect to the commenter 

who suggested that the proposed use 

conditions limiting concentrations of 

HFO–1234yf below the LFL would not 

allow use except in systems initially 

designed to use this refrigerant, we note 

that this decision is limited to use in 

new motor vehicles and light-duty 

trucks. Further, the proposed use 

conditions limiting refrigerant 

concentration are not included in the 

final rule and thus do not have 

implications for a future decision 

concerning retrofits. 

Comment: One commenter provided 

test results from the Bundesanstalt fu ̈r 

Materialforschung und –pru ̈fung 

(BAM—Federal Institute for Materials 

Research and Testing) that tested 

various mixtures of HFO–1234yf and 

ethane (EPA–HQ–OAR–2008–0664– 

0053.3). The commenter stated that the 

tests show that explosions can occur at 

HFO–1234yf concentrations below its 

lower flammability limit (LFL) of 6.2% 

when minimal amounts of gaseous 

hydrocarbons are available. This 

commenter stated that the maximum 

concentrations of HFO–1234yf allowed 

under any use condition need to be far 

below the 6.2% LFL to ensure safety. 

Other commenters agreed with these 

concerns. Yet other commenters looked 

at the same test data and stated that the 

testing was not relevant to real-world 

situations in MVAC because it is 

unlikely that such large amounts of 

ethane or other gaseous hydrocarbons 

(0.8–2.4% by volume) would form in a 

vehicle. One commenter stated that 

HFO–1234yf reduces the flammability 

of ethane compared to ethane alone, and 

that HFO–1234yf reduces flammability 

of ethane more than CO2 or argon, 

substances used as fire suppressants 

(EPA–HQ–OAR–2008–0664–0115.1). 

Response: We do not believe that the 

BAM testing of the flammability limits 

of mixtures of HFO–1234yf and ethane 

is relevant to assessing the risks of 

HFO–1234yf as a refrigerant in MVAC. 

Examples of flammable substances in 

the engine compartment may include 

compressor oil mixed with the 

refrigerant, motor oil, cleaners, antifreeze, transmission fluid, brake fluid, 

and gasoline. These are typically liquid 

and there is no evidence that any vapors 

that might form would include 

significant amounts of ethane. These 

fluids typically contain larger molecules 

with higher boiling points than ethane 

(e.g., octane, polyalkylene glycol). It 

seems more likely, as one commenter 

suggested, that these flammable fluids 

would ignite before breaking down into 

concentrations of ethane considered in 

the BAM testing. Further, the results of 

the testing are not surprising; based on 

a scientifically known chemical 

equilibrium principle known as Le 

Chatelier’s principle—the lower 

flammability limit of a mixture of two 

flammable substances falls between the 

lower flammability limits of the two 

individual substances. The range of 

LFLs for flammable mixtures of ethane 

and refrigerants HFC–134a, HFO– 

1234yf, and CO2 is largest for CO2 and 

is similar for HFC–134a and HFO– 

1234yf (Besnard, 1996). 

A more relevant test to compare risks 

for HFO–1234yf and other alternative 

refrigerants in MVAC is to consider 

flammability of a mixture of compressor 

oil and refrigerant, as occurs in MVAC 

systems. Such testing, conducted as part 

of the SAE CRP, found that mixtures of 

HFO–1234yf and 5% oil and HFC–134a 

and 5% oil both ignited at temperatures 

higher than what usually occurs in a 

vehicle (730 °C or higher for HFO– 

1234yf and 800 °C or higher for HFC– 

134a). 

Furthermore, we note that the final 

use conditions do not rely on the lower 

flammability limit. As explained in 

more detail in sections IV and V of the 

preamble, ‘‘What are the final use 

conditions and why did EPA finalize 

these use conditions?’’ and ‘‘Why is EPA 

finding HFO–1234yf acceptable subject 

to use conditions?’’, we believe that the 

risks from HFO–1234yf and its 

decomposition products are very small 

and are comparable to or less than the 

risks from other acceptable alternatives 

available or potentially available for use 

in MVAC systems. The use conditions 

established in this final rule require 

manufacturers to design systems to 

prevent leakage from refrigerant system 

connections that might enter the 

passenger cabin, and to minimize 

impingement of refrigerant and oil onto 

hot surfaces, as required by SAE J639 

(adopted 2011). These use conditions 

will further reduce already low risks 

from flammability and HF generation. 

Comment: One commenter provided 

data from a presentation showing that 

the lower flammability limit of HFO– 

1234yf decreases as temperature 

increases. The commenter stated that 

the proposed LFL of 6.2% may not be 

conservative enough. 

Response: EPA agrees that the LFL 

decreases as temperature increases. 

However, for the analysis relied on for 

the proposed rule, we considered an 

LFL relevant to the temperatures that 

might be expected in a collision or leak 

scenario and that would not be so high 

as to be a higher risk factor than 

exposure to HF. The data provided by 

the commenter show an LFL of 5.7% at 

60 °C (140 °F) and an LFL of 5.3% at 

100 °C (212 °F). If a passenger were 

exposed to temperatures this high in the 

passenger compartment for any 

extended period of time, he or she 

would suffer from the heat before there 

was a risk of the refrigerant igniting. 

However, after considering the available 

information, we find it is not necessary 

to require a concentration of HFO– 

1234yf below the LFL to address this 

refrigerant’s risks; rather, risks are 

sufficiently addressed with the final use 

conditions. As discussed above in 

section IV of the preamble, ‘‘What are 

the final use conditions and why did 

EPA finalize these conditions?’’, we 

believe that the flammability risks from 

HFO–1234yf are very small and overall 

risks from HFO–1234yf are comparable 

to or less than the risks from other 

acceptable alternatives used in MVAC. 

EPA finds that the use conditions in this 

final rule are sufficient to manage risks 

of injury or adverse health effects 

caused by HFO–1234yf. 

Comment: Regarding the first 

proposed use condition that would limit 

the concentration of HFO–1234yf below 

the LFL in the passenger cabin, several 

commenters stated that the risks of 

refrigerant leaking into the passenger 

compartment and exceeding the LFL are 


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very low. Some automobile 

manufacturers stated that it may not be 

possible to keep the concentration 

below the LFL in the event of a 

collision; however, the commenters said 

that even if concentrations in the 

passenger cabin exceeded the LFL, it 

would be extremely difficult to ignite 

the refrigerant. Some commenters stated 

that the engineering strategies that 

would be necessary to implement the 

proposed use condition would actually 

increase overall risk by increasing the 

risk of conveying smoke and fumes from 

the engine compartment into the 

passenger compartment in the event of 

an accident. Some commenters 

suggested alternative language for the 

use condition to give greater flexibility 

in engineering responses to allow for 

differences between vehicles. 

Response: As discussed above in 

section IV of the preamble, EPA is not 

including the proposed use condition 

requiring that a specific level of 

refrigerant concentration inside the 

passenger cabin is not exceeded. 

Comment: One commenter suggested 

that the use conditions for limiting 

concentrations in the passenger cabin 

should require the incorporation of 

engineering strategies and/or devices 

‘‘such that foreseeable leaks’’ rising to 

the specified concentration levels can be 

avoided. Similarly, the commenter 

stated that any use condition limiting 

concentrations in the engine 

compartment should be limited to 

‘‘prevention of ignition caused by 

foreseeable leaks.’’ The commenter 

noted that EPA did this in a similar use 

condition in its final SNAP rule for 

HFC–152a, another flammable 

refrigerant for MVAC with greater 

flammability risk. The commenter stated 

that this would be consistent with safety 

requirements of the National Highway 

Traffic Safety Administration (NHTSA) 

and would ensure that EPA’s use 

conditions are feasible. 

Response: As discussed above in 

section IV of the preamble, EPA is not 

including the proposed use condition 

and is not limiting the refrigerant 

concentration inside the passenger 

cabin or the engine compartment. 

Comment: A number of commenters 

did not support the proposed use 

condition on concentrations of HFO– 

1234yf in hybrid and electric vehicles. 

One commenter recommended 

eliminating this use condition, as the 

SAE CRP risk assessment concludes 

there are no real world safety risks. 

Another commenter suggested referring 

to the SAE or ISO (International 

Organization for Standardization) 

standards in place of a specific use 

condition. One commenter stated that 

electric terminals on hybrid vehicles are 

well protected to prevent fires and 

should not ignite the refrigerant. 

Another commenter stated that an 

accident severe enough to cause 

refrigerant leakage would also result in 

damage to the duct between the 

evaporator [in the MVAC system] and 

the battery pack, preventing an increase 

in refrigerant concentrations at the 

battery pack. One commenter stated that 

it is difficult to establish generic SNAP 

use conditions for hybrid vehicles, and 

individual manufacturers need to 

understand particular design features of 

their hybrid vehicles to ensure safe 

refrigerant application. 

Three commenters expressed concern 

for using HFO–1234yf in hybrid and 

electric vehicles and stated that the use 

condition is not conservative enough. 

One commenter stated that the 

maximum concentrations of HFO– 

1234yf need to be far below the 6.2% 

LFL based on new tests done at the 

Federal Institute for Materials Research 

and Testing (BAM) and that they are 

unsure whether or not additional 

measures can effectively avoid the risk 

of explosive mixtures. Another 

commenter stated that HFO–1234yf 

would raise concerns in the field of 

battery cooling needed in electric 

vehicles because flammability and 

chemical reactions would pose major 

risks, which could lead to legal 

consequences for OEMs. 

Response: As discussed above in 

section IV of the preamble, EPA is not 

including the proposed use condition 

and is not requiring protective devices, 

isolation and/or ventilation techniques 

where levels of refrigerant concentration 

may exceed the LFL in proximity to 

exhaust manifold surfaces or near 

hybrid or electric vehicle power 

sources. As discussed above, we do not 

believe that the BAM testing of the 

flammability limits of mixtures of HFO– 

1234yf and ethane is relevant to 

assessing the risks of HFO–1234yf as a 

refrigerant in MVAC. Based on 

information provided by OEMs that 

manufacture hybrid vehicles, we 

conclude that there will be sufficient 

protection against fire risk and 

generation of HF in the engine 

compartment for hybrid vehicles 

because they have protective coverings 

on power sources that will prevent any 

sparks that might have enough energy to 

ignite refrigerant and engine surfaces 

will not be hotter than those in 

conventional vehicles (EPA–HQ–OAR– 

2008–0664–0081.1, –0081.2). Further, 

we agree that it is reasonable to assume 

that a collision severe enough to release 

refrigerant from the evaporator (under 

the windshield) would also release it in 

a location far enough away from the 

battery pack to keep refrigerant 

concentrations at the battery pack below 

the LFL. CFD modeling performed for 

the December, 2010 SAE CRP risk 

assessment found that concentrations of 

HFO–1234yf only exceeded the LFL 

within ten centimeters of the leak or less 

(EPA–HQ–OAR–2008–0664–0056.2), 

but the battery pack is typically placed 

more than ten centimeters away from 

the evaporator. EPA expects that OEMs 

will include assessment of risks from 

the exhaust manifold, hybrid power 

source, and electric vehicle power 

source as part of the FMEA required 

under one of the final use conditions in 

this rule. 

Comment: Some commenters 

responded to EPA’s request for 

comment as to whether the use 

conditions should apply only when the 

car ignition is on. These commenters 

indicated that it is unnecessary for the 

use conditions on refrigerant 

concentrations within the passenger 

compartment to apply while a vehicle’s 

ignition is off because it is unlikely that 

a collision would occur, that high 

temperatures would occur, or that 

refrigerant would enter the passenger 

cabin when the ignition, and thus the 

MVAC system, is off. Another 

commenter stated that it should be 

mandatory for all electric power sources 

to be shut off when the ignition is off. 

Response: As discussed above in 

section IV of the preamble, EPA is not 

including the proposed use conditions 

that specified a refrigerant concentration 

not to be exceeded. 

Comment: Several commenters stated 

that the proposed limits on 

concentrations of HFO–1234yf in the 

engine compartment cannot be met, 

even hypothetically, and that 

imposition of such a use condition 

would delay or even prevent the use of 

HFO–1234yf. Other commenters stated 

that the engineering required to meet 

the proposed use condition is almost 

certain to preclude the use of HFO– 

1234yf by any vehicle that was not 

initially designed to use this refrigerant. 

Response: EPA is not including in the 

final rule the proposed use condition 

that sets a specific limit for refrigerant 

concentrations inside the engine 

compartment. See section IV of the 

preamble, ‘‘What are the final use 

conditions and why did EPA finalize 

these conditions?’’ for further rationale. 

Comment: Several commenters agreed 

with EPA’s proposal to require use of 

unique fittings and a warning label that 

identify the new refrigerant and restrict 

the possibility of cross-contamination 

with other refrigerants. Other 

commenters suggested that no use 


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conditions are necessary because 

established standards and practices 

would be adequate for safe use of HFO– 

1234yf. 

Response: The use conditions 

referenced by the commenters were 

established in a separate final rule, 

promulgated in 1996, which applies to 

all refrigerants used in MVAC (see 

appendix D to subpart G of 40 CFR part 

82). EPA has not proposed to modify 

that existing rule for purposes of its 

acceptability determination for HFO– 

1234yf. These requirements indicate to 

technicians the refrigerant they are 

using and thus help reduce risks to the 

technician by ensuring that the 

technician will handle the refrigerant 

properly. In addition, these use 

conditions serve to prevent 

contamination of refrigerant supplies 

through unintended mixing of different 

refrigerants. For purposes of meeting 

that existing regulatory requirement, 

this final rule specifies use of fittings for 

the high-pressure side service port, the 

low-pressure side service port, and for 

refrigerant containers of 20 pounds or 

greater. The submitter for HFO–1234yf 

has provided these fittings to the 

Agency and they are consistent with the 

SAE standard J639. In addition, the final 

rule retains the requirement for a 

warning label identifying the refrigerant, 

consistent with SAE J639. 

Comment: Some commenters agreed 

with EPA’s proposal to require a highpressure compressor cut-off switch, as 

per SAE J639. Another commenter 

suggested that the compressor cut-off 

switch would be useful for all systems 

in which the discharge pressure can 

reach the burst pressure, not just those 

systems with pressure relief devices. 

Response: EPA is maintaining the 

requirement that HFO–1234yf MVAC 

systems must have a high-pressure 

compressor cut-off switch by requiring 

compliance with the SAE J639 standard. 

The SAE J639 standard requires a 

pressure relief device on the refrigerant 

high-pressure side of the compressor for 

all MVAC systems, and so the 

compressor cut-off switch will be 

required for all systems, as suggested by 

the commenter. 

Comment: Several commenters 

supported the requirement for vehicle 

makers to conduct and maintain 

FMEAs. Other automobile 

manufacturers stated that the final 

SNAP rule finding HFC–152a acceptable 

as a substitute for CFC–12 in MVAC 

included this as a comment rather than 

as a use condition, and suggested that 

EPA do the same in the final rule for 

HFO–1234yf. Another commenter stated 

that FMEAs for each vehicle design are 

standard industry practice, and so no 

use condition is required; this 

commenter provided language for an 

alternate use condition should EPA 

choose to specify a use condition for 

vehicle design. 

Response: EPA is retaining the 

requirement for FMEAs in the final rule 

as a use condition, rather than simply as 

an unenforceable comment. In an 

FMEA, vehicle designers analyze all the 

ways in which parts of the MVAC 

system could fail and identify how they 

will address those risks in design of the 

system. In addition, keeping records of 

an FMEA is important to ensuring safe 

use because it documents that vehicle 

designers have complied with the safety 

requirements of this rule. We believe 

that it is necessary to retain this 

requirement as a use condition in order 

to ensure that OEMs are required to 

analyze and address the risks and to 

document those efforts such that this 

analysis is available to demonstrate 

compliance to EPA in case of an EPA 

inspection. Information in the FMEAs 

complements the safety requirements in 

SAE J639 and is useful for 

demonstrating compliance. Because the 

revised SAE J639 standard refers to use 

of FMEAs more extensively, risk 

assessment using FMEAs is more 

critical for HFO–1234yf than it was for 

HFC–152a 

Comment: A commenter requested 

that EPA specifically allow 

manufacturers to perform FMEAs 

according to equivalent standards 

developed by organizations other than 

SAE (e.g., the International Organization 

for Standardization [ISO], the German 

Institute for Standards [DIN], or the 

Japan Automobile Manufacturers 

Association [JAMA]). 

Response: We agree that standards 

from other standard-setting 

organizations may provide equivalent 

assurance of safe use. However, we are 

not aware at this time of any standards 

that do so. In order to ensure safe use 

of HFO–1234yf, we would need to 

review any other standard to ensure that 

it provides equivalent assurances of 

safety before allowing its use in place of 

the SAE standard. An OEM, for 

example, could petition EPA’s SNAP 

program and provide copies of the other 

standard for consideration. If we agree 

that the other standard is equivalent, 

then we would add it to the use 

condition on FMEAs through a 

rulemaking. 

Comment: A commenter expressed 

that EPA’s approach to setting use 

conditions infringes upon the 

Department of Transportation’s motor 

vehicle safety jurisdiction and that EPA 

does not have the authority to protect 

against any fire risk associated with 

motor vehicles. 

Response: As an initial matter, we 

note that the commenter does not point 

to any specific legislative authority that 

supports his claim. Regardless, EPA 

disagrees with this commenter. Section 

612 of the CAA provides that EPA may 

find substitutes for ODS acceptable if 

they present less risk to human health 

and the environment than other 

substitutes that are currently or 

potentially available. Congress did not 

establish any limits on EPA’s authority 

for ensuring that substitutes are not 

more risky than other substitutes that 

are available and EPA has consistently 

interpreted this provision to allow the 

Agency to establish use conditions to 

ensure safe use of substitutes. In this 

case, we find that HFO–1234yf may be 

used safely, and with risks comparable 

to or less than those of other available 

substitutes for CFC–12 in the MVAC 

end-use, so long as it is used according 

to the use conditions established by this 

action. If the commenter were correct 

that the Department of Transportation 

(DOT) has sole authority to address 

safety risks from MVAC systems, in the 

absence of standards from DOT 

addressing HFO–1234yf’s risks, EPA 

would need to determine that HFO– 

1234yf is unacceptable for use in 

MVACs. 

C. Environmental Impacts 

1. Ozone Depletion Potential 

Comment: Several commenters agreed 

with EPA’s proposed finding that HFO– 

1234yf would not contribute 

significantly to stratospheric ozone 

depletion, and that the ozone depletion 

potential (ODP) of HFO–1234yf is at or 

near zero. Two commenters claimed 

that the ODP of HFO–1234yf should be 

stated as ‘‘zero’’ instead of ‘‘nearly zero,’’ 

and one commenter requested that EPA 

clarify that HFO–1234yf has an ODP 

less than that of HFC–134a. 

Other commenters disagreed with 

EPA’s statement that the ODP of HFO– 

1234yf is at or near zero. One 

commenter expressed concern that ODS 

may be used in the HFO–1234yf 

manufacturing process, or emissions of 

HFO–1234yf and its by-products from 

the manufacturing process may break 

down into gases with ODPs; this 

commenter advised EPA against listing 

HFO–1234yf as an acceptable 

replacement for HFC–134a in MVACs. 

Another commenter stated that HFO– 

1234yf requires further investigation 

since unsaturated HFCs such as HFO– 

1234yf might break down into gases that 

are ozone depleting. 


Emcdonald on DSK2BSOYB1PROD with RULES2
17500 Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011 / Rules and Regulations 

17The Agency for Toxic Substances and Disease 

Registry (ATSDR) has established a chronic 

inhalation minimal risk level (MRL) of 0.008 ppm 

(8,000 ppt) for formaldehyde (ICF, 2010d). MRLs 

are available online at http://www.atsdr.cdc.gov/ 

mrls/mrls_list.html. 

18EPA has established a Reference Concentration 

(RfC) of 0.005 ppm (5,000 ppt or 0.009 mg/m3) for 

acetaldehyde (ICF, 2010d). A summary of EPA’s 

documentation for its risk assessment and RfC 

derivation for acetaldehyde is available online at 

http://www.epa.gov/ncea/iris/subst/0290.htm. 

Response: It is generally agreed 

among scientists that substances that 

contain chlorine, bromine or iodine may 

have an ozone depletion potential while 

those that contain only fluorine 

effectively have no ODP. In particular, 

this is because the CF3 radical produced 

from HFCs has negligible reactivity 

(Ravishankara et al., 1993); the same 

radicals would be expected from HFO– 

1234yf. HFO–1234yf contains no 

chlorine, bromine, or iodine. Also, the 

atmospheric lifetime of HFO–1234yf is 

estimated at only 11 to 12 days (Orkin 

et al., 1997; Papadimitrou et al., 2007), 

further reducing the amount of the 

chemical that could possibly reach the 

stratosphere. Unsaturated HFCs, such as 

HFO–1234yf, have at least one double 

bond or triple bond between two carbon 

atoms. Double bonds, like those in 

HFO–1234yf, are less stable than single 

bonds. A saturated HFC, such as HFC– 

134a, has only single bonds between 

atoms of carbon, and is thus more 

stable. Although HFO–1234yf may be 

more unstable than HFC–134a, EPA is 

not aware of any chemical reactions or 

decomposition pathways that would 

cause HFO–1234yf or its breakdown 

products to lead to ozone depletion and 

the commenter has provided no 

technical or scientific support for their 

claims. For purposes of our 

determination, whether its ODP is zero 

or nearly zero, we expect HFO–1234yf 

to have negligible impact on the ozone 

layer and we are listing it as acceptable, 

subject to use conditions. 

2. Global Warming Potential 

Comment: Several commenters agreed 

with EPA’s statement that HFO–1234yf 

has a global warming potential (GWP) of 

4 over a 100-year time horizon. Some 

commenters noted the potential 

environmental benefits of having a 

lower GWP refrigerant available. Other 

commenters stated that HFO–1234yf 

would not be a solution to high global 

warming impacts because of 

environmental and health impacts of 

breakdown products, including HF, 

trifluoroacetic acid (TFA), and 

aldehydes. 

Response: EPA continues to believe 

that the 100-yr GWP of HFO–1234yf is 

4, as supported by the commenters. We 

further agree with the commenters who 

state that there will be an environmental 

benefit if car manufacturers switch to 

HFO–1234yf from HFC–134a, a 

refrigerant with a GWP of 1430 relative 

to CO2.

We disagree with the commenters 

who claim that environmental and 

health impacts of breakdown products 

are a major cause for concern or will 

prevent HFO–1234yf from being a 

useful solution to high global warming 

impacts. One commenter mentioned 

concerns about HF in the atmosphere, 

but HFO–1234yf does not decompose to 

form significant amounts of HF in the 

atmosphere. In fact, HFC–134a and 

HFC–152a result in more HF in the 

atmosphere than HFO–1234yf because 

those two compounds decompose to 

form both COF2, carbonyl fluoride (and 

then HF and CO2) and CF3COF, 

trifluoroacetyl fluoride (and then TFA); 

in contrast, HFO–1234yf favors forming 

trifluoroacetyl fluoride (and then TFA) 

and does not decompose to carbonyl 

fluoride or to HF (ICF, 2010d). For a 

discussion on the potential human 

health impacts of HF, see sections V and 

VII.D.3, ‘‘Why is EPA finding HFO– 

1234yf acceptable subject to use 

conditions?’’ and ‘‘Toxicity of Hydrogen 

Fluoride.’’ 

The fluorinated breakdown product 

that we have identified of greatest 

concern is TFA, because of its 

persistence and potential impacts on 

aquatic plants. As discussed above in 

section V and below in section VII.C.5, 

‘‘Formation of Trifluoroacetic Acid and 

Ecosystem Impacts,’’ the projected 

concentrations of TFA, based on a 

conservative analysis, will be far below 

the level expected to cause any adverse 

impacts on aquatic life. 

EPA agrees that the breakdown 

products from the decomposition of 

HFO–1234yf will include aldehydes, 

but we disagree that this is a cause for 

concern. As part of the analysis of the 

atmospheric breakdown products of 

HFO–1234yf, we found that worst-case 

concentrations of formaldehyde would 

reach 6 to 8 parts per trillion (ppt) on 

a monthly basis or an average of 3 ppt 

on an annual average basis, compared to 

a health-based limit of 8000 ppt,17 i.e., 

a level that is roughly 1000 to 2600 

times lower than the health-based limit 

(ICF, 2010d). Acetaldehyde levels 

would be even lower, with worst-case 

concentrations of 1.2 ppt and annual 

average concentrations of 0.23 ppt, 

compared to a health-based limit of 

5000 ppt 18 (ICF, 2010d). As discussed 

further below in section VII.D.1 of the 

preamble, ‘‘Toxicity of HFO–1234yf,’’ 

these concentrations are one to three 

orders of magnitude less than ambient 

concentrations of formaldehyde and 

acetaldehyde without the introduction 

of HFO–1234yf (ICF, 2010d). Thus, 

aldehydes that would be decomposition 

products of HFO–1234yf in the 

atmosphere would not contribute 

significantly to adverse health effects for 

people on earth’s surface. 

Other fluorinated alternatives that are 

acceptable in the MVAC end-use, HFC– 

134a and HFC–152a, also create 

fluorinated breakdown products, and 

there is not evidence to show that those 

from HFO–1234yf create significantly 

more risk for human health or the 

environment than breakdown products 

from other alternatives. Thus, even 

assuming that risks from breakdown 

products would exist, based on use of 

HFO–1234yf in the MVAC end-use, we 

do not believe those risks are greater 

than the risks posed by other acceptable 

alternatives. 

3. Lifecycle Emissions of HFO–1234yf 

Comment: One commenter stated that 

HFO–1234yf has the best global 

lifecycle climate performance (LCCP) 

and lower CO2 [equivalent] emissions 

compared to other alternatives. 

However, another commenter stated that 

HFO–1234yf has a lower 

thermodynamic efficiency than HFC– 

134a and that its use could lead to 

increases in CO2 and other air pollutant 

emissions. The same commenter stated 

that there is no assurance that 

automakers would voluntarily add 

technologies to maintain current levels 

of MVAC efficiency when using HFO– 

1234yf. 

Response: We note that EPA has 

chosen to use GWP as the primary 

metric for climate impact for the SNAP 

program, while also considering energy 

efficiency (March 18, 1994; 59 FR 

13044). We have not used specific 

lifecycle metrics such as Total 

Equivalent Warming Impact (TEWI), 

Lifecycle Analysis (LCA) or LCCP as 

metrics for climate impact, since it is 

not clear that there is agreement in all 

industrial sectors or end-uses on which 

of these measures is most appropriate in 

which situations or how these metrics 

are to be calculated (SROC, 2005). 

The available information on 

efficiency, LCCP and lifecycle emissions 

for MVAC does not raise concern that 

the indirect climate impacts from HFO– 

1234yf will cause significantly greater 

impacts on human health and the 

environment than other available 

alternatives. Looking at some of the 

information referenced by the 

commenters, we learned that: 

• Bench testing for the Japan 

Automobile Manufacturers 

Association (JAMA) and the Japan 


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19Papasavva et al. (2009) includes several sources 

of emissions of automobile refrigerant, including 

regular leaks through hoses, irregular leaks, 

refrigerant loss during servicing, and refrigerant loss 

at end of vehicle life. 

20Prepublication version of Wallington et al., 

2010 (Docket item EPA–HQ–OAR–2008–0664– 

0084.2) 

Auto Parts Industry Association 

(JAPIA) found a system efficiency 

(coefficient of performance) for HFO– 

1234yf that is roughly 96% of that for 

HFC–134a (JAMA–JAPIA, 2008) 

• LCCP analysis conducted by JAMA 

found that indirect CO2 equivalent 

emissions from less efficient fuel 

usage due to use of the MVAC system 

were a few percent higher for HFO– 

1234yf and roughly 20 to 25% higher 

for CO2, compared to HFC–134a 

(JAMA, 2008) 

• JAMA’s LCCP analysis found that 

when both direct emissions of 

refrigerant and indirect emissions 

from less efficient fuel usage are 

considered, HFC–134a has higher 

total climate impact than either HFO– 

1234yf or CO2; in hotter climates like 

Phoenix, Arizona, HFC–134a has 

higher total climate impact than 

HFO–1234yf but slightly lower 

climate impact than CO2; and in all 

cases, HFO–1234yf had the lowest 

total climate impact of the three 

alternatives. (JAMA, 2008) 

• MVAC systems can be designed to 

improve efficiency through steps such 

as changing the compressor, sealing 

the area around the air inlet, changing 

the thermal expansion valve, 

improving the efficiency of the 

internal heat exchanger, adding an oil 

separator to the compressor, and 

changing the design of the evaporator. 

Optimized new MVAC systems using 

either HFO–1234yf or CO2 can reduce 

fuel usage compared to current MVAC 

systems using HFC–134a. (Benouali et 

al., 2008; Meyer, 2008; Monforte et 

al., 2008) 

EPA believes that there is good reason 

to expect that automobile manufacturers 

will choose to design new cars using 

more efficient MVAC components and 

systems than in the past because of 

recent regulations. The Department of 

Transportation has issued new 

regulations raising the Corporate 

Average Fuel Economy standards for 

vehicles and EPA has issued new 

regulations restricting greenhouse gas 

emissions from light-duty vehicles (75 

FR 25324; May 7, 2010). Thus, in order 

to ensure that their fleets meet these 

standards, it is highly likely that 

automobile manufacturers will include 

MVAC systems optimized for efficiency 

in future models, regardless of the 

refrigerant used. 

Comment: Concerning an appropriate 

rate of emissions for estimating 

environmental impacts of HFO–1234yf, 

three commenters recommended that 

EPA use 50 g per vehicle per year total 

lifecycle emission rate. These 

commenters cited the work of 

Wallington et al. (2008) and Papasavva 

et al. (2009).19 Another commenter 

stated that HFO–1234yf is very likely to 

have a lower leak rate than HFC–134a, 

citing data on permeability for both 

refrigerants. 

Response: EPA agrees that the 

permeability data indicate that regular 

leakage emissions of HFO–1234yf, 

which are released slowly through 

hoses, are likely to be lower than those 

from HFC–134a. However, this is only a 

portion of total emissions expected 

because emissions may also come 

through irregular leaks due to damage to 

the MVAC system, refrigerant loss 

during servicing, and refrigerant loss at 

the end of vehicle life. In response to 

the commenters who suggested that we 

use an annual emission rate of 50 g/ 

vehicle/yr, we reexamined 

environmental impacts as part of our 

final environmental analysis (ICF, 

2010c) using the recommended 50 g/ 

vehicle/yr value and compared this to 

the impacts calculated assuming 

emissions are similar to those from 

HFC–134a in MVAC, as we did at the 

time of proposal (closer to 100 g/ 

vehicle/yr). The emission values from 

using 50 g/vehicle/yr (i.e., values from 

the Pappasavva et al. (2009) study) were 

26.3% to 51.1% less than the emission 

estimates used in our analysis at the 

time of proposal (ICF, 2009; ICF, 2010a; 

ICF, 2010c). In either case, as described 

more fully in section V above and in 

sections VII.C.4 and VII.C.5, below, the 

overall environmental impacts on 

generation of ground-level ozone and of 

TFA were sufficiently low and the 

impacts of HFO–1234yf are not 

significantly greater than those of other 

available substitutes for MVAC. For 

further information, see the ICF analyses 

in the docket (ICF, 2010a,b,c,e). 

4. Ground-Level Ozone Formation 

Comment: Some commenters 

expressed concern about a potential 

increase in ground-level ozone of 

> 1–4% calculated in EPA’s initial 

assessment (ICF, 2009) of environmental 

impacts of HFO–1234yf. Other 

commenters stated that HFO–1234yf 

will not contribute significantly to 

ground-level ozone. One commenter 

suggested that EPA provide an updated 

assessment of the potential contribution 

of HFO–1234yf to ground-level ozone, 

considering the additional information 

provided in public comments (e.g., 

Luecken et al., 2009 and Wallington et 

al., 2009).20

Response: We proposed that HFO– 

1234yf would be acceptable, even with 

a worst-case increase in ground-level 

ozone of > 1 to 4%. In response to 

comments, EPA performed a new 

analysis that (1) used revised estimates 

of the expected emissions of HFO– 

1234yf; and (2) used reactions with 

ozone formation from hydroxyl radicals 

rather than using sulfur dioxide (SO2) as 

a surrogate for the hydroxyl radical, 

OH , and rather than making 

assumptions about the relative reactivity 

of compounds. Our revised analysis 

(ICF, 2010b) estimates that emissions of 

HFO–1234yf might cause increases in 

ground-level ozone of approximately 

0.08 ppb or 0.1% of the ozone standard 

in the worst case, rather than an 

increase of 1.4 to 4% as determined in 

our initial analysis (ICF, 2009). This 

value also agrees with results from 

Kajihara et al., 2010 and Luecken et al., 

2009. This revised analysis provides 

additional support that HFO–1234yf 

will not create significant impacts on 

ground level ozone formation or on 

local air quality. 

Comment: Some commenters 

disagreed with EPA’s statement that 

HFO–1234yf has a photochemical ozone 

creation potential (POCP) comparable to 

that of ethylene (100), while others 

agreed with this conclusion. One 

commenter provided a peer reviewed 

study that estimated the POCP of HFO– 

1234yf to be 7 (Wallington et al., 2010). 

Response: Based on the comments 

received and additional studies, EPA 

believes that the initial assessment that 

assumed a POCP of 100 to 300 is overly 

conservative. We have revised our 

initial analysis to incorporate reaction 

kinetics specific to HFO–1234yf, 

consistent with Luecken et al., 2009, 

which avoids making an assumption of 

POCP. EPA’s revised analysis estimates 

worst-case increases in ground-level 

ozone formation of approximately 0.1% 

(ICF, 2010b). Compared to the 

uncertainty in the sources of emissions, 

the uncertainty in the measures that 

localities will take to meet the ozone 

standard, and the uncertainty in the 

analysis, a projected worst-case increase 

in ozone of 0.1% is not significant for 

purposes of determining that HFO– 

1234yf poses substantially greater 

human health or environmental risk 

than other alternatives. This provides 

further support for our proposed 

determination that the conditioned use 

of HFO–1234yf does not present a 


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17502 Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011 / Rules and Regulations 

significantly larger risk to human health 

and the environment compared to HFC– 

134a, and in many cases likely poses 

less risk. For further information, see 

the analysis of environmental impacts 

in section V of the preamble, ‘‘Why is 

EPA finding HFO–1234yf acceptable 

subject to use conditions?’’ and see the 

analysis in the docket (ICF, 2010b). 

Comment: A commenter provided a 

link to a paper (Carter, 2009) that found 

the maximum incremental reactivity 

(MIR) for HFO–1234yf to be about the 

same as that for ethane. Based on the 

MIR value for HFO–1234yf, some 

commenters stated that EPA should find 

HFO–1234yf to be exempt from the 

definition of VOC. 

Response: (Note: EPA has previously 

found certain compounds exempt from 

the definition of ‘‘volatile organic 

compound’’ [VOC] for purposes of air 

regulations in State Implementation 

Plans, 40 CFR 51.100(s), if they have a 

MIR equal to or less than that of ethane 

on a mass basis [69 FR 69298, November 

29, 2004; 74 FR 29595, June 23, 2009; 

also see interim EPA guidance at 70 FR 

54046, September 13, 2005].) In a 

separate rulemaking process, EPA is 

considering whether to list HFO–1234yf 

under 40 CFR 51.100(s) as exempt from 

the definition of VOC for purposes of air 

regulations that States may adopt in 

State Implementation Plans. 

5. Formation of Trifluoroacetic Acid and 

Ecosystem Impacts 

Comment: Several commenters agreed 

with EPA’s proposed finding that the 

projected maximum concentration of 

TFA in rainwater from degradation of 

HFO–1234yf does not pose a significant 

aquatic toxicity risk. Other commenters 

raised concern about the potential 

impacts of TFA on biodiversity, 

ecosystems, and human health. One 

commenter questioned the 

sustainability of HFO–1234yf, so long as 

there are questions remaining about its 

environmental fate and degradation. 

One commenter stated that artificial 

input of TFA into the environment 

should be avoided because of its toxicity 

and chemical properties. Another 

commenter stated that HFO–1234yf 

poses additional environmental 

concerns compared to HFC–134a and 

advised against finding it acceptable 

while the issue of TFA production is 

being further researched. 

Response: We continue to conclude 

for purposes of our decision here that 

the degradation of HFO–1234yf into 

TFA does not pose a significant risk of 

aquatic toxicity or ecosystem impacts. 

All available research indicates that, 

assuming emissions are no more than 

twice the current level of emissions 

from HFC–134a from MVAC, TFA 

concentrations in surface water and 

rainwater will be on the order of 1/ 

800th to 1/80th of the no observed 

adverse effect level (NOAEL) for the 

most sensitive known alga (Luecken et 

al., 2009; Kajihara et al., 2010). We have 

revised our analysis on TFA 

concentrations using the known 

reaction kinetics of HFO–1234yf. The 

revised estimate of the worst-case TFA 

concentration in rainwater is 

approximately 1700 ng/L, similar to the 

concentrations in Luecken et al. (2009) 

of 1260 ng/L and Kajihara et al. (2010) 

of 450 ng/L. We believe this provides a 

sufficient margin of protection to find 

that the use of HFO–1234yf in MVAC 

will not pose significantly greater risks 

than other available alternatives in this 

end-use. 

Comment: Some commenters stated 

that further research on TFA is 

necessary. 

Response: EPA has considered 

additional studies submitted during the 

public comment period (Luecken et al., 

2009; Kajihara et al., 2010) and has 

performed further analysis on this issue. 

Luecken et al. (2009) predicted through 

modeling that in the U.S., HFO–1234yf 

used in MVAC would result in enough 

TFA to increase its concentration in 

rainwater to 1/80th to 1/800th of the 

NOAEL for the most sensitive plant 

species considered. Kajihara et al. 

(2010) predicted through modeling that 

in Japan, HFO–1234yf use in all 

potential refrigeration uses would 

increase the TFA concentration in 

surface water to no more than 1/80th of 

the NOAEL for the most sensitive plant 

species considered. This study also 

found that surface water concentrations 

were roughly twice those in rainwater. 

Thus, even with highly conservative 

modeling that also considered 

accumulation in surface water, the 

concentrations of TFA are likely to be at 

least 80 times lower than a level 

expected to have no impact on the most 

sensitive aquatic species. 

We also performed a further modeling 

analysis using refined assumptions on 

emissions and the mechanisms by 

which HFO–1234yf might break down. 

We found that the worst-case 

concentration of TFA would be 

approximately 1700 ng/L, similar to the 

concentrations in Luecken et al. (2009) 

of 1260 ng/L and Kajihara et al. (2010) 

of 450 ng/L (ICF, 2010b). These 

additional studies and analyses indicate 

even less risk than the studies available 

at the time of proposal and thus provide 

further support that TFA emissions from 

MVAC system will not pose a 

significant risk of aquatic toxicity or 

ecosystem impacts. 

We also note that EPA has an 

obligation to act on submissions in a 

timely manner under the Clean Air Act 

(§ 612(d)). Given that research to date 

has not indicated a significant risk, we 

disagree that the Agency should delay a 

final decision to await further studies 

that may be done in the future. If future 

studies indicate that HFO–1234yf poses 

a significantly greater environmental 

risk than we now believe, section 612(d) 

provides a process for an interested 

party to petition the Agency to change 

a listing decision. 

Comment: Two commenters stated 

that EPA’s initial modeling (EPA–HQ– 

OAR–2008–0664–0037) greatly 

overestimates the local deposition of 

TFA from oxidation of HFO–1234yf. In 

particular, one commenter claimed that 

the modeling’s use of the oxidation of 

SO2 to sulfate ion, SO3

–, as a proxy for 

the oxidation of HFO–1234yf is overly 

conservative because a large portion of 

SO2 is in aerosol form, unlike for HFO– 

1234yf. This commenter also referred to 

the impacts found in the peer-reviewed 

paper by Luecken et al. (2009). 

Response: EPA agrees that the use of 

the oxidation of SO2 to SO3

– as a proxy 

for the oxidation of HFO-1234yf likely 

results in overestimating TFA 

concentrations. This is because the 

sulfate particle is a condensation 

nucleus in the wet deposition process 

and it has a very high removal efficiency 

compared to the gas phase process for 

wet deposition that acts with HFO– 

1234yf and its decomposition products. 

Further, TFA forms more slowly from 

HFO–1234yf than sulfate forms from 

SO2 (ICF, 2010b). 

We have repeated the modeling using 

refined assumptions on emissions and 

the mechanisms by which HFO–1234yf 

might break down. This revised 

assessment (ICF, 2010b) found TFA 

concentrations roughly one-thousandth 

those in the earlier assessment (1700 ng/ 

L compared to 1,800,000 ng/L in ICF, 

2009). This additional research provides 

stronger support for our conclusion that 

the degradation of HFO–1234yf into 

TFA does not pose a significant risk of 

aquatic toxicity or ecosystem impacts. 

Comment: Some commenters 

disagreed with a statement in the ICF 

(2009) analysis concerning TFA 

concentrations in surface waters, that 

‘‘the exception to this is vernal pools 

and similar seasonal water bodies that 

have no significant outflow capacity.’’ 

These commenters believe that 

Boutonnet et al. (1999) showed that 

accumulation of trifluoroacetate, a 

compound closely related to TFA, was 

rather limited in seasonal water bodies. 

The commenters also stated that 

Benesch et al. (2002) conducted an 


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Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011 / Rules and Regulations 17503 

21Predictive ability of the autoradiographic repair 

assay in rat liver cells compared with the Ames test; 

S. Parodi; M. Taningher; C. Balbi; L. Santi; Journal 

of Toxicology and Environmental Health, Vol. 10, 

Issue 4 & 5, October 1982, pages 531–539. 

22 Kirkland et al. (2005) Evaluation of a battery of 

three in vitro genotoxicity tests to determine rodent 

carcinogens and non-carcinogens. I. Sensitivity, 

specificity and relative predictivity, Mutation 

Research, 584, 1–256. 

experimental study of the impacts of 

TFA on vernal pools, in which no 

impacts were observed. 

Response: The statement from ICF, 

2009 in context stated: 

NOECs [No-observed effect 

concentrations] were compared to 

rainwater TFA concentrations because 

for most water bodies, it is difficult to 

predict what the actual TFA 

concentration will be. This is because 

concentrations of environmental 

contaminants in most fresh water bodies 

fluctuate widely due to varying inputs 

and outputs to most ponds, lakes, and 

streams. Comparison of NOECs to 

rainwater concentrations of TFA is 

actually more conservative because TFA 

is expected to be diluted in most 

freshwater bodies. The exception to this 

is vernal pools and similar seasonal 

water bodies that have no significant 

outflow capacity. (ICF, 2009) 

We note that the ‘‘exception’’ 

described in the analysis is an exception 

to the expectation that TFA will be 

diluted more in freshwater bodies than 

in rainwater. We believe that the 

available evidence confirms that vernal 

pools do not dilute TFA as much as 

freshwater bodies with outflow 

capacity. Modeling by Kajihara et al., 

2010 found surface water concentrations 

were roughly twice those in rainwater. 

However, even these concentrations 

were not high enough to be of 

significant concern for environmental 

impacts. As noted previously, even the 

highest levels of TFA concentrations 

were at least 80 times less than the 

NOAEL for the most sensitive aquatic 

species examined. 

D. Health and Safety Impacts 

1. Toxicity of HFO–1234yf 

Comment: Three commenters stated 

that there are no toxicity concerns with 

using HFO–1234yf, and two 

commenters noted that HFO–1234yf is 

comparable to HFC–134a in terms of 

human health effects. One commenter 

also stated that HFO–1234yf does not 

present a developmental toxicity or 

lethality risk. Seven commenters stated 

that there are potential toxicity concerns 

with use of HFO–1234yf. One 

commenter cautioned EPA against 

listing HFO–1234yf as acceptable for 

use in MVACs on the grounds of 

increased concerns over developmental 

effects and other toxic effects on human 

health. 

Response: EPA continues to believe 

that HFO–1234yf, when used in new 

MVAC systems in accordance with the 

use conditions in this final rule, does 

not result in significantly greater risks to 

human health than the use of other 

available or potentially available 

substitutes, such as HFC–134a or CO2.

The results of most of the toxicity tests 

for HFO–1234yf either confirmed no 

observed adverse health effects, or 

found health effects at similar or higher 

exposure levels than for HFC–134a. For 

example, HFC–134a caused cardiac 

sensitization at 75,000 ppm but HFO– 

1234yf did not cause cardiac 

sensitization even at 120,000 ppm, the 

highest level in the study (NRC, 1996; 

WIL 2006). NOAELs from subacute 

exposure were higher for HFO–1234yf 

than for HFC–134a (NOAELs of 51,690 

for HFO–1234yf with no effects seen in 

the study, compared to 10,000 ppm for 

HFC–134a with lung lesions and 

reproductive effects seen at 50,000 ppm 

[NRC, 1996; TNO, 2005]). No adverse 

effects were seen at 50,000 ppm or any 

other level in subchronic (13-week) 

studies for both HFO–1234yf and HFC– 

134a (NRC, 1996; TNO, 2007a). 

In mutagenicity testing for HFO1234yf, the two most sensitive of five 

strains of bacteria showed mutation; 

however, this screening test for 

carcinogenic potential is known to have 

only a weak correlation with 

carcinogenicity (Parodi et al., 1982; 21

Kirkland et al., 2005 22), so a positive 

result in this test for the two most 

sensitive strains is not sufficient reason 

to consider HFO–1234yf to be a 

significant health risk. Mutagenicity 

testing for HFC–134a by the same test 

found no evidence of mutagenicity. 

Screening for carcinogenic potential in 

a genomics study did not identify HFO– 

1234yf as a likely carcinogen (Hamner 

Institutes, 2007). A two-year cancer 

assay for HFC–134a did not find 

evidence of carcinogenicity (NRC, 

1996). 

EPA considers the results of 

developmental testing to date to be of 

some concern, but not a sufficient basis 

to find HFO–1234yf unacceptable for 

purposes of this action under the SNAP 

program. In a developmental study on 

rats, cases of wavy ribs were seen in 

some developing fetuses during 

exposure to HFO–1234yf (TNO 2007b); 

however, effects on bone formation were 

also seen for HFC–134a (NRC, 1996). It 

is not clear if this effect is reversible or 

not. Interim results from a twogeneration reproductive study did not 

find an association between exposure to 

HFO–1234yf and skeletal effects. This 

two-generation reproductive study for 

HFO–1234yf finds a NOAEL of 5000 

ppm for delayed mean time to vaginal 

opening in F1 females (females in the 

first generation of offspring). A subacute 

(28-day) test for HFC–134a (single 

generation) found a NOAEL of 10,000 

ppm for male reproductive effects (NRC, 

1996). A developmental test on rabbits 

exposed to HFO–1234yf did not find 

effects on the developing fetus. 

However, some of the mother rabbits in 

this study died. The reason for the 

deaths is not known. The data on 

developmental effects are inconsistent 

depending on the test performed and 

the species tested. The development 

effects observed in the developmental 

study on rats are not significantly 

different from the developmental effects 

observed for HFC–134a. In any case, as 

discussed above in section V and below 

in this section, our risk assessments 

found that HFO–1234yf would likely be 

used with exposure levels well below 

those of concern in the uses allowed 

under this rule. Thus, we do not find 

the observed developmental effects 

sufficient reason for finding HFO– 

1234yf unacceptable in this rule. 

For purposes of this action, we 

prepared our risk assessment for longterm exposure using the level at which 

no deaths or other adverse health effects 

were seen in the rabbit developmental 

study—a ‘‘no observed adverse effect 

level’’ or NOAEL—to ensure that 

exposed people would be protected. The 

longer-term, repeated exposure in that 

study would be the exposure pattern 

(though not necessarily the exposure 

level) for a worker using HFO–1234yf 

on a regular basis or for a consumer 

exposed in a car due to a long, slow leak 

into the passenger compartment. Using 

the NOAEL concentration of 4000 ppm 

as a starting point, we found no 

situations where we expect exposure to 

exceed the level that EPA considers safe 

for long-term or repeated exposure 

(EPA–HQ–OAR–2008–0664–0036). 

Thus, we consider the potential toxicity 

risks of HFO–1234yf for those uses 

allowed under this action to be 

addressed sufficiently to list it as 

acceptable subject to use conditions. 

Comment: Based on a risk assessment 

conducted by one commenter, the 

commenter concluded that if HFO– 

1234yf is used under the conditions 

specified in the commenter’s risk 

assessment, adverse health impacts 

would not be expected to car occupants, 

to servicing personnel, or to do-ityourself (DIY) consumers. This 

commenter noted differences between 

the margin-of-exposure approach to 


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assessing risk, as in EPA’s risk 

assessment (EPA–HQ–OAR–2008– 

0664–0036), and the commenter’s 

hazard index (HI) approach. The 

commenter further stated that in all 

cases, the predicted hazard index for 

HFO–1234yf was only one-half of the 

values predicted for HFC–134a, and in 

some cases, only one-third of the HFC– 

134a values, demonstrating from a 

health perspective that HFO–1234yf is a 

viable alternative to HFC–134a. 

Response: EPA agrees that adverse 

health impacts would not be expected to 

car occupants or to servicing personnel, 

so long as the use conditions of this rule 

are observed. However, EPA has issued 

a Significant New Use Rule under TSCA 

(October 27, 2010; 75 FR 65987) that 

would require submission of additional 

information to EPA prior to the 

manufacture, import or processing of 

HFO–1234yf for certain uses, including 

distribution in commerce of products 

intended for use by a consumer for the 

purposes of servicing, maintenance and 

disposal involving HFO–1234yf (e.g., 

‘‘do-it-yourself’’ servicing of MVAC 

systems). 

Where available, it is EPA policy to 

use a NOAEL (No-Observed-AdverseEffect Level) for the point of departure 

(POD) for risk assessment. This is the 

highest exposure level that did not 

cause an adverse health effect in a 

study. In this case, EPA selected the 

POD from an animal (rat 2-week 

inhalation) study. Because animals may 

respond to different exposure levels 

than humans, there is some uncertainty 

when extrapolating from animals to 

humans. For this reason, an Uncertainty 

Factor (UF) is applied when 

extrapolating from animals to humans— 

typically a factor of 10 is used but, in 

this case, since there was a reasonable 

estimate of the pharmacokinetic 

component of the uncertainty, this UF 

was reduced to 3. An additional UF is 

applied to account for variation in the 

human population response to a 

chemical exposure—in this case, a UF of 

10 was used. The two UFs give a 

resultant UF of 30 to yield an acceptable 

level of health risk. As stated in the final 

SNUR, EPA’s policy for review of new 

chemicals under TSCA is to divide the 

POD by the exposure level to obtain the 

MOE. For HFO–1234yf, the ‘‘acceptable 

level of health risk’’ would be an MOE 

of 30 or greater. 

The commenter proposed dividing the 

estimated exposure to HFO–1234yf by 

the POD levels to obtain a HI. As a 

result, if the exposure is less than the 

POD, the HI is < 1 and the commenter 

considered this an ‘‘acceptable level of 

health risk.’’ The commenter’s approach 

to the hazard index does not factor in 

uncertainties about extrapolating from 

animal to human responses, nor does it 

address variability within the human 

population with regard to thresholds of 

response to chemical exposures. EPA 

has consistently applied the margin of 

exposure (MOE) approach to 

evaluations of pre-manufacture notices 

(and for certain other risk assessments) 

in order to account for the uncertainties 

discussed above. The SNAP program 

considered work performed during 

evaluation of the pre-manufacture 

notice (EPA–HQ–OAR–2008–0664– 

0036), as well as a separate SNAP 

program risk screen (EPA–HQ–OAR– 

2008–0664–0038). SNAP program risk 

screens compare expected exposures to 

exposure limits that incorporate 

uncertainty factors based on EPA 

guidance, rather than calculating either 

a hazard index or a margin of exposure. 

Any of these approaches to risk 

assessment will come to a similar 

conclusion about whether there is a 

potential health concern when using the 

same point of departure, uncertainty 

factors, and exposure estimates. 

The Agency and the commenter 

disagree on all three of these inputs to 

the risk assessment and hence have 

reached different conclusions. Despite 

these differences, the assessments relied 

on by both the commenter and EPA 

show that there is low risk both to car 

occupants and to service technicians. 

EPA’s risk assessment indicates a 

potential risk to DIYers (EPA–HQ– 

OAR–2008–0664–0036). As stated 

previously in this action, this issue is 

further addressed through the Agency’s 

authority under TSCA. 

Comment: In response to EPA’s risk 

assessment (EPA–HQ–OAR–2008– 

0664–0036), two commenters disagreed 

with the use of a 2-week study for 

evaluating 30 minute exposures and 

stated that acute toxicity (4-hour test) or 

cardiac sensitization test results would 

be more appropriate for acute exposure 

evaluations. 

Response: Commenters have 

suggested that EPA use data from the 

4-hour acute toxicity study or from the 

cardiac sensitization study as a starting 

point (‘‘point of departure’’) for assessing 

risks of short-term (acute) exposure. 

However, cardiac sensitization studies 

are for very short durations—on the 

order of 10 minutes—and they only 

address cardiac sensitization. HFO– 

1234yf does not induce cardiac 

sensitization. EPA selected the point of 

departure for acute effects from a 

multiple-exposure 2-week (subacute) rat 

inhalation study on HFO–1234yf, 

reasoning that if no effects were seen in 

the duration of the study (6 hours per 

day, 5 days per week for 2 weeks), that 

no effects would be seen from a single 

exposure at a similar exposure level, 

either. Further, the subacute exposure 

rat study included more thorough 

pathology examinations than those 

included in a cardiac sensitization 

study. 

The acute 4-hour exposure study in 

rats showed some lung effects at 

approximately 200,000 ppm, the lowest 

exposure level in the study. Thus EPA 

considers 200,000 ppm to be a LOAEL 

(Low-Observed-Adverse-Effect Level). If 

a LOAEL were used in the risk 

assessment instead of a NOAEL, EPA 

would use an uncertainty factor to 

estimate a NOAEL, which would result 

in a lower POD than what was used. For 

example, if EPA had started with the 

LOAEL of 200,000 ppm, it would have 

required an additional MOE of 10 to 

estimate a NOAEL from a LOAEL, for a 

total MOE of 300 instead of 30. This 

would have resulted in a more 

conservative risk assessment than using 

the NOAEL from the 14-day subacute 

study. In the 4-hour acute toxicity 

study, some of the animals had grey, 

discolored lungs at all exposure levels 

in the study, and we considered this an 

adverse effect. Thus, EPA could only 

determine a lowest observed adverse 

effect level (LOAEL) from the 4-hour 

acute study and could not determine a 

no observed adverse effect level 

(NOAEL). It is longstanding Agency 

policy to use the NOAEL where 

available instead of a LOAEL, because of 

greater assurance of a safe exposure 

level. EPA instead used the NOAEL for 

the next shortest study, the subacute 14- 

day study, as the endpoint of concern 

for short term exposure because the 

LOAEL from the acute 4-hour study is 

an endpoint showing effects that may 

not result in safe exposure levels for 

humans. If we had used the value from 

the 4-hour acute toxicity study, we 

would have had to consider additional 

uncertainty that would have resulted in 

a more conservative, more restrictive 

risk assessment than using the NOAEL 

from the 14-day subacute study. 

Further, EPA has uncertainties about 

using the available single exposure 

studies on HFO–1234yf to determine the 

MOEs for different exposure scenarios. 

As a result of concerns with these 

studies, EPA calculated single exposure 

MOEs from the NOAEL in the 2-week 

inhalation toxicity study of HFO–1234yf 

in rats. There are some uncertainties in 

the single exposure (acute) assessments 

because of the observation of lethality in 

rabbit dams after multiple exposures to 

HFO–1234yf in a developmental study. 

For these reasons, EPA recommended 

an acute inhalation toxicity study on 

rabbits in the proposed SNUR to address 


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23The Agency for Toxic Substances and Disease 

Registry (ATSDR) has established a chronic 

inhalation minimal risk level (MRL) of 0.008 ppm 

(8,000 ppt) for formaldehyde (ICF, 2010d). MRLs 

are available at http://www.atsdr.cdc.gov/mrls/ 

mrls_list.html. 

24EPA has established a Reference Concentration 

(RfC) of 0.005 ppm (5,000 ppt or 0.009 mg/m3) for 

acetaldehyde (ICF, 2010d). A summary of EPA’s 

documentation for its risk assessment and RfC 

derivation for acetaldehyde is available online at 

http://www.epa.gov/ncea/iris/subst/0290.htm. 

the question of whether pregnant rabbits 

would die from a single exposure (April 

2, 2010; 75 FR 16706). 

Comment: A commenter asserted that 

EPA’s methodology to estimate the 

exposure levels associated with the DIY 

use, using the SAE CRP (2008) Phase II 

Report, greatly exaggerates the exposure 

that could be experienced in actual use 

conditions. Another commenter 

calculated exposure to a DIYer assuming 

that the refrigerant fills a garage and 

concluded that exposure would be less 

than the manufacturer’s recommended 

exposure limit of 1000 ppm. The first 

commenter stated that the 30 minute 

time-weighted average (TWA) value 

used by the EPA is unrealistic as are the 

exposure estimates presented in 

Scenarios 1 and 2 of the supporting 

document EPA–HQ–OAR–2008–0664– 

0036. The specific exposure parameters 

that the commenters questioned were 

assumptions regarding: 

• Garage volume; 

• Time the user spent under the hood 

during recharging operations; 

• The size of the space where any 

leaking gas would disperse; 

• The air exchange rate in a service 

area that should be well-ventilated 

when the engine is running; 

• Use of the refrigerant in a closed 

garage with no ventilation; and, 

• The amount of refrigerant used 

during recharge operations. 

During the comment period for the 

proposed SNUR, the PMN and SNAP 

submitter conducted a simulated 

vehicle service leak testing, using HFC– 

134a as a surrogate, indicating that 

exposures from use of a 12-oz can 

during consumer DIY use are below the 

Agency’s level of concern for HFO– 

1234yf (Honeywell, 2010a). 

Response: Concerning exposure 

estimates for DIYers, the exposure 

values in the EPA risk assessment 

(EPA–HQ–OAR–2008–0664–0036) are 

bounding estimates of the maximum 

possible theoretical concentrations. The 

EPA assessment used the industrymodeled DIY scenarios and assumptions 

in a 2008 report by Gradient 

Corporation for the SAE CRP (CRP, 

2008) as a starting point for creating the 

bounding estimates. To do so, EPA 

assumed that the entire leakage mass of 

each industry-modeled scenario was 

released to its corresponding volume 

with no air exchange. These 

assumptions are conservative and 

protective, as intended. 

We considered the calculations 

provided by one commenter that 

assumed that the refrigerant fills a 

garage. However, this analysis assumes 

a longer-term, steady-state concentration 

after the refrigerant has diffused 

throughout the garage and uses a longterm, 8-hour time-weighted average 

exposure recommendation for 

comparison. EPA’s concerns about DIY 

consumer exposure focuses on shortterm acute exposures, including peak 

exposures over a few minutes near the 

consumer’s mouth and nose because 

typically a DIY consumer will only need 

a short period of time to recharge a 

single MVAC system (Clodic et al., 

2008). Thus, the commenter’s 

calculations do not address EPA’s 

concerns. 

After reviewing the consumer DIY use 

exposure study from the SNAP/PMN 

submitter, EPA responded with a list of 

clarifying questions (U.S. EPA, 2010c), 

to which the submitter subsequently 

responded (Honeywell, 2010b). 

Although the submitter’s responses 

were helpful, EPA still has concerns 

about potential exposures to consumers 

during DIY use and the inherent toxicity 

of HFO–1234yf. However, since this 

acceptability determination is limited to 

use with fittings for large containers, 

which DIYers would not purchase, our 

concerns about potential health risk to 

DIY users need not be addressed in this 

action. We would plan to evaluate this 

issue further before taking a final action 

on a SNAP submission for unique 

fittings for small containers. We further 

note that the Agency would analyze this 

issue in the context of any SNUN filed 

pursuant to the recently issued SNUR 

(75 FR 65987). Although we do not 

reach any conclusion in this final rule 

regarding safe use by DIYers, we make 

the following observations about the 

submitted study. With regards to 

exposure, the peak concentration values 

from the submitted study are as high as 

3% by volume, equivalent to 30,000 

ppm. These peaks appeared to occur in 

the first one or two minutes of each 

emission. Accordingly, EPA would need 

exposure data presented and averaged 

out over shorter Time Weighted 

Averages (TWAs) than the 30 minutes 

currently in the study, because it would 

appear that a number of these early 

exposure peaks could result in TWA 

values that would result in MOEs less 

than the acceptable Agency level of 30 

described above in this section. This is 

important because the data on HFO– 

1234yf are insufficient to differentiate 

whether the toxicity is due to blood 

level alone from an acute exposure, is 

due to accumulated exposure over time 

(‘‘area under the curve’’), or is due to 

some combination of both. Since blood 

equilibrium levels are reached within 

minutes, a high level of exposure in a 

short duration could result in blood 

levels exceeding a threshold if the mode 

of action of the toxicity of HFO–1234yf 

is due to blood levels of the chemical. 

EPA expects that exposure data with 

additional TWAs of 3, 5, and 10 minutes 

would help to resolve these issues of 

consumer exposure. 

Comment: One commenter stated that 

HFOs could harm the human nervous 

system. The commenter cited a diagram 

of breakdown products in a slide 

presentation given by the Montreal 

Protocol Scientific Assessment Panel in 

July 2009 and suggested that the toxic 

impact of aldehydes formed as 

breakdown products would be higher 

than that of carbonic acids. 

Response: EPA agrees that the 

breakdown products from the 

decomposition of HFO–1234yf will 

include aldehydes, but we disagree that 

this is a cause for concern. The 

aldehydes that would be produced as 

atmospheric breakdown products of 

HFO–1234yf are formaldehyde and 

acetaldehyde (ICF, 2010d). Their health 

effects include respiratory effects; 

irritation of the eyes, nose, and throat; 

and corrosion of the gastrointestinal 

tract. EPA also considers formaldehyde 

and acetaldehyde to be probable human 

carcinogens (U.S. EPA, 2000; ICF, 

2010d). The decomposition products of 

HFO–1234yf are not noted for causing 

neurotoxic effects, and toxicity tests for 

HFO–1234yf did not identify this as an 

effect. 

As part of analysis of the atmospheric 

breakdown products of HFO–1234yf, we 

found that worst-case concentrations of 

formaldehyde would reach 6 to 8 parts 

per trillion (ppt) on a monthly basis or 

an average of 3 ppt on an annual average 

basis, compared to a health-based limit 

of 8000 ppt 23—i.e., a level that is 

roughly 1000 to 2600 times lower than 

the health-based limit (ICF, 2010d). 

Acetaldehyde levels would be even 

lower, with worst-case concentrations of 

1.2 ppt and annual average 

concentrations of 0.23 ppt, compared to 

a health-based limit of 5000 ppt 24 (ICF, 

2010d). Thus, aldehydes that would be 

decomposition products of HFO–1234yf 

in the atmosphere would not contribute 

significantly to adverse human health 

effects (ICF, 2010d). 

Aldehydes, including formaldehyde 

and acetaldehyde, are already present in 


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the atmosphere in significant amounts 

from natural sources such as plants, 

from direct emissions, from combustion 

products, or from breakdown of other 

compounds such as hydrocarbons (NRC, 

1981; Rhasa and Zellner, 1987). The 

current background level of 

formaldehyde in the atmosphere ranges 

from 80 ppt in pristine areas to 

approximately 3300 ppt in New York, 

NY—one to three orders of magnitude 

more than the worst-case generation of 

formaldehyde from HFO–1234yf (ICF, 

2010d). The maximum incremental 

acetaldehyde concentration calculated 

due to use of HFO–1234yf was 

approximately three orders of 

magnitude less than the average 

concentration of acetaldehyde in areas 

with pristine air quality (ICF, 2010d). 

Thus, the additional aldehydes created 

during decomposition of HFO–1234yf in 

the atmosphere are not likely to have a 

significant impact on human health. 

Comment: Some commenters stated 

that additional research and review of 

the available information regarding 

toxicity of HFO–1234yf needs to be 

conducted. 

Response: EPA has an obligation to 

act on submissions in a timely manner 

under the Act (§ 612(d)). Our risk 

assessments to date have found no 

significant risk for car passengers or 

drivers, professional servicing 

personnel, or workers disposing of or 

recycling vehicles containing HFO– 

1234yf. We believe these assessments 

are sufficient to support this action. We 

note that these assessments rely on 

somewhat conservative assumptions. 

We note that we expect there will be 

no toxicity risks to DIYers because EPA 

must receive and take regulatory action 

to allow unique fittings for use with 

small cans of refrigerant before DIYers 

could be exposed, as per appendix D to 

subpart G of 40 CFR part 82. Further, 

because HFO–1234yf is not expected to 

be introduced into any new cars until 

late 2011 or later, we expect to have 

further information and to take further 

action before DIYers could be exposed. 

In addition, the final SNUR would not 

allow distribution in commerce of 

products intended for use by a 

consumer for the purposes of servicing, 

maintenance and disposal involving 

HFO–1234yf until at least 90 days after 

submission of a SNUN. 

We recognize that more studies will 

be performed on HFO–1234yf, further 

addressing risk. EPA’s New Chemicals 

Program has recommended additional 

testing of acute exposure in rabbits, 

including pregnant rabbits (April 2, 

2010; 75 FR 16706). In addition, the 

manufacturer is voluntarily conducting 

a multi-generation reproductive study. If 

these or other future studies call into 

question the basis for our decision 

today, section 612 allows citizens to 

petition EPA to change or modify a 

listing decision or EPA could determine 

on its own to reassess this decision. 

Comment: In late comments, a 

commenter stated that EPA appears to 

be relying on a SNUR to reduce risks to 

human health from exposure to HFO– 

1234yf. This commenter stated that EPA 

must re-open the comment period on 

the proposed SNAP rule so that 

commenters may reassess the extent to 

which the final restrictions of the SNUR 

will be effective at limiting adverse 

human health effects. The same 

commenter noted that information on 

new price levels and availability is 

needed to assess the effectiveness of the 

SNUR. 

Response: EPA’s final SNUR 

addresses potential risks to human 

health from exposure to HFO–1234yf. 

However, as discussed above in section 

V of the preamble, ‘‘Why is EPA listing 

HFO–1234yf as acceptable subject to use 

conditions?’’, this final SNAP rule does 

not allow for the use of HFO–1234yf 

with small cans or containers (i.e., 

container sizes that would be purchased 

by DIY users, such as small cans and 

containers less than 5 lbs) because it 

does not contain specifications for 

unique fittings for can taps and for these 

smaller containers. Existing SNAP 

program regulations in appendix D to 

subpart G of 40 CFR part 82 require the 

use of unique fittings for specific 

purposes (e.g., high pressure-side 

service port, small can taps) for each 

MVAC refrigerant, as submitted by the 

refrigerant manufacturer. Before HFO– 

1234yf can be introduced in small 

containers typically used by DIYers, the 

manufacturer must submit unique 

fittings to EPA, we must conclude that 

they are unique, and we must issue new 

proposed and final rules specifying 

those fittings. In addition, the final 

SNUR would not allow distribution in 

commerce of products intended for use 

by a consumer for the purposes of 

servicing, maintenance and disposal 

involving HFO–1234yf until at least 90 

days after submission of a SNUN. These 

and other requirements ensure—to the 

extent possible, with the information 

currently available to EPA—that HFO– 

1234yf has no greater risk overall for 

human health and the environment than 

other available refrigerants for MVAC. 

Under the final SNUR, it is necessary 

for EPA to receive and complete its 

review of a significant new use notice 

(SNUN) with additional information on 

consumer exposure risks before—if the 

Agency so decides—HFO–1234yf may 

be manufactured, imported or processed 

for the purpose of use in DIY servicing, 

with or without other restrictions. We 

would also consider information in the 

SNUN before issuing a final rule 

specifying unique fittings for use with 

small containers of refrigerant. 

In comments EPA received on the 

proposed SNAP rule, the initial direct 

final SNUR that was withdrawn and the 

proposed SNUR, no commenters 

suggested making the provisions of the 

SNUR stricter or suggested adding use 

conditions under the SNAP program for 

addressing risks to consumers during 

DIY servicing. A number of commenters 

stated that no restrictions were needed 

to address risks to consumers during 

DIY servicing, while other commenters 

stated more broadly that EPA should 

find HFO–1234yf unacceptable because 

of its toxicity risks. We provided an 

additional opportunity for comment on 

the SNAP rule after the direct final 

SNUR was issued (February 1, 2010; 75 

FR 4083), in response to a request to 

reopen the public comment period 

(EPA–HQ–OAR–2008–0664–0077.1), in 

part to allow comment on the 

relationship between these two 

rulemakings that both address HFO– 

1234yf. However, we do not believe that 

the conditions of the final SNUR are 

necessary to the determination that we 

are making here. As noted above, this 

final rule does not allow for the 

servicing of HFO–1234yf from container 

sizes that would be purchased by DIY 

users because of the lack of an approved 

unique fitting for smaller containers. 

Further rulemaking under SNAP will 

occur prior to such use and any risks 

can be addressed in that rulemaking 

package. At that time, we will be able 

to fully consider the impact of the final 

SNUR. 

2. Flammability 

Comment: Five commenters stated 

that HFO–1234yf has a low likelihood of 

ignition, especially under the conditions 

encountered in an automotive 

application. One commenter stated that 

the mere presence of high refrigerant 

concentrations does not contribute to a 

hazardous condition because an ignition 

source of sufficient energy must also be 

present. Another commenter disagreed 

with EPA’s view that a flammability risk 

exists. Other commenters stated that 

additional review of the available 

information regarding flammability of 

HFO–1234yf needs to be conducted. 

Some commenters stated that EPA 

should consider restricting 

concentrations of HFO–1234yf to much 

lower concentrations than to the lower 

flammability limit (LFL) of 6.2%. 

Response: The available evidence 

indicates that HFO–1234yf will not 


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present a significant risk of flammability 

and that any risk it poses is not greater 

than the risk presented by other 

available alternatives. For example, 

because of its higher LFL, its 

considerably higher minimum ignition 

energy (5000 mJ to 10,000 mJ), and its 

slower flame speed (1.5 cm/s), HFO– 

1234yf is less flammable than HFC– 

152a, a substitute that EPA has already 

found acceptable subject to use 

conditions. 

Further, an analysis conducted for 

SAE International’s Cooperative 

Research Program by Gradient 

Corporation (CRP, 2009) found that 

there was a very low flammability risk 

(on order of 10¥14 occurrences per 

operating hour or 1 occurrence in 100 

years across the entire U.S. fleet of 

passenger vehicles). This was due to the 

low probability of achieving a 

concentration of HFO–1234yf above the 

LFL at the same time as having a 

sufficiently high energy source to cause 

the refrigerant to ignite. Further, even 

that low probability of ignition of HFO– 

1234yf may be overstated, because it 

assumes that a vehicle collision severe 

enough to crack open the evaporator 

(located under the windshield and 

steering wheel) is not severe enough to 

crack the windshield or windows that 

would hold refrigerant in the passenger 

compartment. In a sensitivity analysis, 

the SAE CRP considered how the 

flammability risk would change if a 

refrigerant release into the passenger 

compartment only occurs in a collision 

causing damage to more than the MVAC 

system. That analysis estimated that the 

risk of exposure to an open flame would 

then be reduced by a factor of 23,000, 

to approximately 4 × 10¥19 occurrences 

per vehicle operating hour (EPA–HQ– 

OAR–2008–0664–0056.2). 

For the reasons provided above in 

sections IV and VII.B of the preamble, 

‘‘What are the final use conditions and 

why did EPA finalize these use 

conditions?’’ and ‘‘Use conditions,’’ EPA 

does not believe it is necessary to 

establish a use condition limiting 

refrigerant concentrations, whether at 

6.2% or some other, lower value. We 

believe the final use conditions 

sufficiently address flammability risks. 

Comment: Three commenters stated 

that HFO–1234yf is flammable and that 

the proposed regulation does not offer 

any restrictions to protect those persons 

handling HFO–1234yf, nor does it 

restrict its sale and use by the general 

public. 

Response: The purpose of the use 

conditions is to ensure that HFO–1234yf 

will not pose a greater risk to human 

health or the environment than other 

available or potentially available 

substitutes. For all of the reasons 

provided in sections IV and V above, 

EPA has determined that HFO–1234yf 

will not pose a greater risk than other 

substitutes for MVAC. As explained 

above, EPA proposed restricting 

concentrations of the refrigerant below 

the LFL of 6.2% as a use condition. 

Based on comments and additional 

analysis, EPA has concluded that it is 

not necessary to require use conditions 

limiting refrigerant concentrations to 

below the LFL; rather, the use 

conditions now specify design 

parameters for MVAC systems and 

require an FMEA. This will ensure that 

systems are designed to minimize risk 

not only from flammability, but also 

from exposure to HF. 

We will address use by service 

personnel through a rulemaking under 

section 609 of the CAA. Although these 

rules will further address issues of 

interest to service personnel and others 

that might handle HFO–1234yf used in 

MVAC systems, we note that our risk 

assessments of use of HFO–1234yf 

found that significant flammability risks 

do not exist for personnel installing the 

refrigerant at equipment manufacture, 

professional servicing personnel, and 

personnel working with automobiles at 

equipment end-of-life (EPA–HQ–OAR– 

2008–0664–0036 and –0038). Moreover, 

we note that an industry-sponsored 

analysis of risks found the risk of 

ignition of HFO–1234yf to a technician 

is extremely small, on the order of 10¥26

occurrences per working hour (EPA– 

HQ–OAR–2008–0664–0056.2). 

As we have explained above, this rule 

only addresses the use of large 

containers for professional use 

(typically 20 lbs or larger) and thus 

HFO–1234yf may not be used in small 

container sizes that would be the type 

purchased by the general public. We 

will address the issue of risk to DIY 

users through a future rulemaking under 

SNAP if we receive a request for unique 

fittings for smaller containers from the 

refrigerant manufacturer. We also are 

addressing risks to DIY users through 

the Significant New Use Rule under the 

Toxic Substances Control Act (October 

27, 2010; 75 FR 65987). 

Comment: One commenter stated that 

compared with HFC–134a, the 

explosion probability of HFO–1234yf is 

much higher based on testing done at 

the Federal Institute for Materials 

Research and Testing (Bundesanstalt fu ̈r 

Materialforschung und-pru ̈fung, BAM). 

Other commenters disagreed with those 

flammability conclusions, finding the 

testing results to be expected but not 

representative of real-world use in 

MVAC. These commenters stated that 

the flammability risks of HFO–1234yf 

were not significant and that the 

mixtures of HFO–1234yf and ethane 

used in the testing would not be seen in 

MVAC in actual operations. 

Response: As explained above in 

section VII.B, we do not believe that 

these tests are relevant for assessing the 

flammability risks of HFO–1234yf as 

used in MVAC systems because they 

evaluated flammability based on the 

presence of ethane, a substance that 

should not be present in any situation 

that might cause flammability risks for 

MVAC systems. 

3. Toxicity of Hydrogen Fluoride (HF) 

Comment: Two commenters stated 

that there is low risk due to exposure to 

HF. One of these commenters stated that 

(1) for vehicles that do not discontinue 

the use of the blower after collision, the 

risk due to exposure to HF from use of 

HFO–1234yf is approximately twice the 

risk with the current use of HFC–134a, 

and (2) for vehicles that discontinue the 

use of the blower after collision, the risk 

due to exposure to HF when using 

HFO–1234yf is approximately the same 

as that with the current use of HFC– 

134a (on order of 10¥12 occurrences per 

operating hour, or one in one trillion). 

The second commenter stated that there 

is no need for concentration limits to 

protect against exposure to HF because 

the risks from exposure to HF from 

HFO–1234yf are similar to what would 

be experienced with HFC–134a. One 

commenter also stated that 

concentrations of HF as low as 0.3 ppm 

cause a sensation of irritation. The 

commenter stated that this characteristic 

would deter someone from remaining 

exposed to excessive concentrations 

from an open hood. 

Other commenters stated that there is 

a high probability of HF generation in 

cars from HFO–1234yf. One commenter 

stated that the flammability of HFO– 

1234yf makes the production of HF 

more likely and increases the risk of HF 

exposure to vehicle passengers, to 

workers at chemical facilities, 

automotive manufacturing facilities, 

vehicle servicing facilities, and to the 

general public. Two commenters stated 

that various health and safety concerns 

related to HF generation and its toxicity 

are well studied and documented, and 

three commenters stated that use of 

HFO–1234yf is unacceptable as there is 

increased potential for HF exposure and 

related casualties. 

Response: EPA has considered the 

potential for generation of HF from 

HFO–1234yf, including the SAE CRP’s 

evaluation of scenarios that might cause 

workplace and consumer exposure to 

HF (EPA–HQ–OAR–2008–0664– 

0056.2). SAE CRP members conducted 


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25An AEGL–2 is intended to apply to an 

emergency situation where someone would try to 

move away from the hazard in a short period of 

time and may suffer some temporary irritation, but 

no permanent health damage. Irreversible or 

disabling but non-fatal health effects could occur 

between the AEGL–2 and the higher AEGL–3. 

tests to measure HF concentrations and 

to identify factors that were most likely 

to lead to HF formation. One set of tests 

conducted in a car found that HF 

measurements inside the passenger 

cabin were 35 ppm or less (EPA–HQ– 

OAR–2008–0664–0056.2). This highest 

value occurred during release of the 

entire charge of refrigerant of 1000 g 

into the passenger cabin with ignition 

started by a butane lighter augmented 

with an additional spark—a highly 

conservative scenario. (A more typical 

charge would be 575 g, and it would be 

unlikely to have the amount of ignition 

energy that occurred artificially in the 

experiment with use of both a butane 

lighter and an additional spark source.) 

A second set of tests focusing on HF in 

the engine compartment tried to 

simulate a major rupture in the AC 

system that would release 12 g/s of 

refrigerant across 5 cm onto an artificial 

hot surface at temperatures of 450 °C 

(typical of the exhaust manifold) and 

700 °C (most extreme case), with the car 

hood in various positions. This testing 

found HF concentrations as high as 120 

ppm at the hot surface in the engine 

compartment in the worst case, with 

interior passenger cabin values of 40 to 

80 ppm in the worst case (EPA–HQ– 

OAR–2008–0664–0056.2). This test was 

conservative for the following reasons: 

The temperature was high, representing 

extreme conditions; the refrigerant was 

released extremely close to the hot 

surface; the hood was closed; and the 

refrigerant ignited briefly. The other test 

trials under less extreme conditions 

resulted in HF concentrations of a few 

ppm. The test trials also found 

somewhat lower concentrations of HF 

generated during testing of HFC–134a 

using the same procedures and 

apparatus, with maximum 

concentration of 36 ppm in the engine 

compartment and concentrations of less 

than 8 ppm in the passenger 

compartment in the worst case. The 

SAE CRP selected an Acute Exposure 

Guideline Limit (AEGL)–2 25 of 95 ppm 

over 10 minutes as its criterion for 

determining excessive risk. This limit 

was developed to protect against 

irreversible health effects when 

exposure remains below the limit of 95 

ppm over 10 minutes, but short-term 

discomfort or irritation could still occur. 

Thus, even assuming a passenger inside 

a vehicle was exposed to HF at the 

highest level found in the test of 80 

ppm, exposure at this level would at 

worst cause discomfort and irritation, 

rather than permanent or disabling 

health effects. 

For both HFO–1234yf and for HFC– 

134a, HF concentrations in the 

passenger compartment fell between the 

level that would protect against all 

adverse health effects (AEGL–1 of 1.0 

ppm for 10 minutes to 8 hours) and the 

level that would protect against 

irreversible or disabling health effects 

(AEGL–2 of 95 ppm over 10 minutes) 

(NRC, 2004). The SAE CRP concluded 

that the probability of such a worst case 

event is on the order of 10¥12

occurrences per operating hour (EPA– 

HQ–OAR–2008–0664–0056.2). 

Commenters provided information 

indicating that this level of risk for HF 

generation is the same order of 

magnitude for both HFC–134a and for 

HFO–1234yf. EPA considers the risk 

level presented by HFO–1234yf to be 

similar to that of the refrigerant 

currently being used by automobile 

manufacturers, HFC–134a. Therefore, 

there is no reason to regulate HFO– 

1234yf more stringently to protect 

against HF exposure than for HFC–134a. 

Comment: One commenter stated that 

testing with HFOs commissioned by the 

environmental organization Greenpeace 

in 2001 hinted at a multitude of 

decomposition products with high 

reactivity. The commenter stated that 

apparently even lubricants 

(polyalkylene glycol—PAG) break down 

to HF when in contact with HFO– 

1234yf in a MVAC system. The 

commenter further expressed that BAM 

testing showed that burning HFO– 

1234yf resulted in concentrations of HF 

greater than 90 ppm in the engine 

compartment. The commenter 

concluded that the tests prove that in a 

standard system with standard charge 

(900 grams) and oil, the risk for humans 

would be incalculable. 

Response: The commenter has not 

provided sufficient information on the 

testing commissioned by Greenpeace in 

2001 for the Agency to determine what 

the results were or whether the testing 

conditions are relevant to this action. 

Concerning the BAM testing, EPA has 

not seen a testing report or a detailed 

description of the experimental method 

that allows for a full evaluation. Based 

on the information provided by the 

commenter, the temperature of the 

released substance reached 600 °C and 

HF concentrations of over 90 ppm were 

measured in the engine compartment. 

According to a risk assessment from an 

automobile manufacturer, such a high 

temperature is unlikely and could only 

be achieved on the exhaust manifold 

under heavy engine loads such as when 

a vehicle is climbing a hill, and the 

temperature of the exhaust manifold 

would drop in a minute or so during 

deceleration (EPA–HQ–OAR–2008– 

0664–0081.1). It is not clear what the 

conditions were for the study 

mentioned by the commenter. For 

example, it is not clear if the refrigerant 

was mixed with compressor oil as it 

normally would be in an MVAC; 

inclusion of oil with a relatively low 

flashpoint would be expected to lead to 

ignition at lower temperatures (EPA– 

HQ–OAR–2008–0664–0056.2; EPA– 

HQ–OAR–2008–0664–0118.1). It also is 

not clear if the compressor fan was 

operating during the test. During normal 

vehicle operation, the fan would cool 

down the compressor and the engine 

compartment, avoiding the temperature 

of 600 °C on hot surfaces in the engine. 

Other tests have found that HF 

concentrations in the engine 

compartment were approximately 5 

ppm or less and only in the worst case 

(hot surface temperature of 700 °C, 

closed hood on engine compartment) 

did HF concentrations attain a value of 

approximately 120 ppm in the engine 

compartment (OAR–2008–0664– 

0056.2). This level is slightly higher 

than the AEGL–2 of 95 ppm on a 

10-minute average and is lower than the 

AEGL–3 for HF of 170 ppm on a 10- 

minute average, the value that would 

protect against life-threatening exposure 

but would not necessarily prevent longterm health effects. However, we note 

that we do not anticipate any 

circumstance where a person would be 

exposed to these levels in an engine 

compartment because such conditions 

would not occur during vehicle 

servicing, but rather during vehicle 

operation. Further, in the case of a 

collision resulting in a fire, we would 

expect that professional first responders 

have training in chemical hazards and 

possess appropriate gear which would 

prevent them from receiving HF 

exposures above health-based limits 

(EPA–HQ–OAR–2008–0664–0056.2) 

and an interested by-stander would 

quickly back away from a fire or from 

irritating HF vapors, thus preventing 

excessive HF exposure. The 

concentration measured in the 

passenger compartment in the same 

worst-case situation was in the range of 

40 to 80 ppm, less than the 

concentration in the engine 

compartment and less than the AEGL– 

2 intended to protect against long-term 

health effects. Thus, we disagree with 

the commenter’s assertion that HF 

exposures from thermal decomposition 

or combustion of refrigerant would be 

likely to result in fatalities. We further 


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note that the HF concentrations found 

in the passenger compartment were 

lower than the health-based limit, the 

AEGL–2 of 95 ppm over 10 minutes. 

We also note that the risks presented 

by HFO–1234yf are not significantly 

different than the risk posed by HFC– 

134a, the refrigerant currently in use in 

MVAC systems. Mixtures of HFC–134a 

and compressor oil also combust and 

generate HF. Testing performed using 

HFC–134a under worst-case conditions 

in the engine compartment (hot surface 

temperature of 700 °C, closed hood on 

engine compartment) found HF 

concentrations as high as 36 ppm in the 

engine compartment and 2 to 8 ppm in 

the passenger compartment. The 

amount of HF generated from a typical 

charge of HFC–134a, if it all burned or 

decomposed, could be even more than 

for the expected charge of HFO–1234yf 

because charge sizes using HFO–1234yf 

are expected to be smaller (EPA–HQ– 

OAR–2008–0664–0056.2). The SAE CRP 

considered potential risks of HF 

exposure from both HFO–1234yf and 

from HFC–134a. Both presented 

potential risks on the order of 10¥12

occurrences per operating hour (EPA– 

HQ–OAR–2008–0664–0056.2, –0096.1). 

This corresponds to less than one case 

per year across the entire fleet of motor 

vehicles in the U.S. Although there is no 

specific testing data on HF production 

from HFC–152a, another acceptable 

refrigerant for MVAC, since this 

compound contains fluorine, it presents 

risks of HF generation as well. As 

discussed above in Section IV of the 

preamble, we are not requiring specific 

use conditions that regulate production 

of HF, either directly or indirectly, 

because of the low level of risk. 

However, the final use conditions in 

this rule address the risks of HF 

production, as well as risks of 

flammability, by requiring certain 

design safety features of MVAC systems 

using HFO–1234yf and by requiring risk 

analysis for each car model through 

FMEAs. 

Comment: A commenter provided 

results from a test by IBExU on the 

decomposition of HFO–1234yf under 

heat (EPA–HQ–OAR–2008–0664– 

0053.3). This commenter strongly 

warned against a decision in favor of 

HFO–1234yf because it would form 

highly toxic HF when burning. Three 

commenters disagreed that the results of 

the IBExU testing were relevant because 

test conditions did not represent 

realistic conditions. One commenter 

said that the SAE risk assessment, 

which used actual vehicle test data for 

HF formation, found that actual HF 

formation rates are far below the levels 

[from the IBExU test results] cited by the 

first commenter, the Federal 

Environmental Agency 

(Umweltbundesamt—UBA). 

Response: The IBExU testing of HF 

generation from HFO–1234yf is not 

relevant to assessing the risks of HFO– 

1234yf as a refrigerant in MVAC. 

Laboratory tests concerning the nature 

of HF generation on hot surfaces found 

that this depends on the contact time of 

reactants on the hot surface, the 

temperature of the hot surface and the 

movement of refrigerant in diluted 

concentrations due to airflow (EPA– 

HQ–OAR–2008–0664–0056.2; EPA– 

HQ–OAR–2008–0664–0116.2). The 

IBExU testing involved heating the 

refrigerant steadily in a sealed flask. 

Thus, the contact time in that test was 

far greater than would occur in an 

engine compartment and the movement 

of refrigerant in that test was essentially 

zero, unlike in an engine compartment 

where there would be constant air 

movement. 

Comment: Another test from BAM 

reported by UBA examined HF 

formation from HFO–1234yf and from 

HFC–134a (EPA–HQ–OAR–2008–0664– 

0080.1). Fifty grams of refrigerant was 

streamed through a hole of 2 mm 

diameter onto a hot metal surface. The 

study found that pure HFO–1234yf 

exploded on the hot surface whereas 

pure HFC–134a did not. The study also 

found that when HFO–1234yf was 

mixed with 3% oil, it exploded at 600 

°C. The commenter stated that handling 

of HFO–1234yf in the presence of hot 

metal surfaces results in HF formation 

in concentrations far above allowed 

workplace concentrations. 

Response: These results are not 

consistent with results from hot-plate 

tests conducted by an automobile 

manufacturer and by a chemical 

manufacturer for the SAE CRP (EPA– 

HQ–OAR–2008–0664–0056.2; EPA– 

HQ–OAR–2008–0664–0115.1). Those 

manufacturers found that neither HFO– 

1234yf nor HFC–134a alone ignited at 

900 °C. One of these tests found that 

HFO–1234yf mixed with PAG oil 

combusted starting at 730 °C, while 

HFC–134a mixed with PAG oil ignited 

at 800 °C and above; the other test 

observed no ignition of a blend of each 

refrigerant with PAG oil at 800 °C, but 

both blends ignited at 900 °C. Based on 

the lack of reproducibility of the 

specific ignition temperature, it appears 

that the specific ignition temperature 

may depend on variables in the testing 

(e.g., flash point of the oil used, amount 

of mixture used, angle of application, 

and air flow available). This information 

also shows that mixtures of refrigerant 

with compressor oil can combust at 

lower temperatures than pure refrigerant 

and that mixtures of HFO–1234yf and 

oil and mixtures of HFC–134a and oil 

present similar risks of ignition and HF 

generation. Thus, we concluded that the 

risks of toxicity from HF exposure due 

to combustion or decomposition of 

HFO–1234yf are comparable to those 

from HFC–134a. 

Further, the risks from toxicity of HF 

posed by both refrigerants are small. 

The SAE CRP estimates this risk on the 

order of 10¥12 cases per operating hour 

(EPA–HQ–OAR–2008–0664–0086.1). 

This is equivalent to less than one event 

per year across the entire fleet of motor 

vehicles in the U.S. For comparison, 

this is less than one ten-thousandth the 

risk of a highway vehicle fire and one 

fortieth or less of the risk of a fatality 

from deployment of an airbag during a 

vehicle collision (EPA–HQ–OAR–2008– 

0664–0056.2). 

E. Retrofit Usage 

Comment: Several commenters stated 

that HFO–1234yf should be allowed 

initially in new vehicles but should not 

be used to retrofit vehicles using HFC– 

134a, or at least not unless there are 

industry standards to guide such a 

process. Other commenters stated that it 

is critical to allow a natural phase-out 

of the fleet of cars using HFC–134a as 

the refrigerant, rather than requiring 

retrofitting existing cars with HFO– 

1234yf. A commenter expressed concern 

that retrofitting of HFC–134a MVAC 

systems with HFO–1234yf would result 

in cases of cross-contamination of 

refrigerant, while another commenter 

contested this statement and found it 

unsupported. Other commenters 

opposed obstacles that would prevent 

older MVACs from being retrofitted to 

the new refrigerant. These commenters 

mentioned the potential for greenhouse 

gas benefits when retrofitting systems 

currently using HFC–134a with HFO– 

1234yf. 

Response: The submitter did not 

request review of HFO–1234yf for 

retrofitting vehicles and thus EPA did 

not review HFO–1234yf as acceptable 

(or acceptable subject to use conditions) 

for retrofitting in MVAC in this 

rulemaking. Consistent with the request 

submitted to the Agency, we proposed 

to find HFO–1234yf acceptable for use 

subject to use conditions in new MVAC 

systems and evaluated its risks only for 

use in new systems. We will consider 

the retrofit use of HFO–1234yf in MVAC 

systems if we receive a submission that 

specifically addresses retrofitting and 

the risks that are unique to retrofitting. 

In response to the commenter who 

raised a concern about a ‘‘phase-out’’ of 

HFC–134a and the potential that we 

would ‘‘require’’ use of HFO–1234yf, we 


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note that our rulemakings under SNAP 

do not require use of any specific 

substitute. Rather, under SNAP, we 

have established lists of substitutes that 

are acceptable for use in various enduses (such as for MVACs) and end-users 

are free to choose which substitute to 

use, but must do so consistent with any 

use conditions that apply. As stated in 

the rule establishing the SNAP program, 

‘‘The Agency * * * does not want to 

intercede in the market’s choice of 

available substitutes, unless a substitute 

has been proposed or is being used that 

is clearly more harmful to human health 

and the environment than other 

alternatives.’’ 59 FR 13046, March 18, 

1994. We further note that this 

rulemaking does not change the status 

of HFC–134a, which remains an 

acceptable substitute for use in MVACs, 

subject to use conditions. 

F. Use by ‘‘Do-it-Yourselfers’’ 

Comment: Some commenters raised 

concerns about EPA’s statements in the 

proposed rule about potential health 

effects that might occur without 

professional training and the use of 

CAA Section 609 certified equipment. 

These commenters stated that the 

studies and testing in the docket 

support a finding that use of HFO– 

1234yf by non-professionals is safe and 

do not offer valid technical support for 

EPA’s concerns. 

Response: EPA’s risk assessment and 

risk screen both indicated that worstcase exposure levels expected during 

servicing by do-it-yourselfers are of 

potential concern (EPA–HQ–OAR– 

2008–0664–0036 and EPA–HQ–OAR– 

2008–0664–0038). In both documents, 

this was based upon estimated exposure 

levels from a 2008 risk assessment by 

Gradient Corporation for the SAE CRP 

(EPA–HQ–OAR–2008–0664–0008). In 

EPA’s risk assessment (EPA–HQ–OAR– 

2008–0664–0036), we found that the 

level that EPA determined did not cause 

health effects in laboratory animals 

might be only 2 to 3 times higher than 

the exposure predicted for that use (the 

‘‘margin of exposure’’). Our risk 

assessment indicated a higher, more 

protective margin of exposure of at least 

30 was needed to account for 

uncertainty in the extrapolation from 

animals to humans and for variability in 

the human population. In other words, 

we found that based on worst-case 

assumptions, a do-it-yourselfer’s 

exposure could be 10 or more times the 

level that EPA considered safe. The 

margin of exposure was calculated using 

a conservative estimated exposure level 

of 45,000 ppm over 30 minutes and a 

human equivalent concentration of 

98,211 ppm from a no-observed adverse 

effect level that we selected as the point 

of departure for risk assessment (EPA– 

HQ–OAR–2008–0664–0036). 

However, under this final rule, unique 

fittings have only been submitted for 

servicing fittings for the high-side and 

low-side ports and for large containers 

of HFO–1234yf and thus the 

acceptability listing is limited to use of 

HFO–1234yf with the unique fittings 

specified (e.g., for large containers of 20 

pounds or more). We expect these 

containers would not be purchased by 

DIYers because of their expense ($800 or 

more per container) and because they 

would contain enough refrigerant for 10 

charges or more. We will continue to 

review the issue of safe use for DIYers 

if and when we are requested to review 

unique fittings for a smaller container 

size. In addition, EPA is further 

addressing the issue of risks to DIYers 

in the Significant New Use Rule for 

1-propene-2,3,3,3-tetrafluoro- (75 FR 

65987, October 27, 2010). This SNUR 

requires submission of a SNUN at least 

90 days before sale or distribution of 

products intended for use by a 

consumer for the purpose of servicing, 

maintenance and disposal involving 

HFO–1234yf. 

EPA’s proposed rule on the use of 

HFO–1234yf as a substitute for CFC–12 

in new MVAC systems did not propose 

to establish use conditions for servicing 

vehicles by certified professionals, but 

our analyses indicate that there is not 

significant risk to certified 

professionals, because HFC–134a, 

which is currently used in most MVAC 

systems, presents similar risks and 

professionals have the knowledge and 

equipment to mitigate any risks. We 

plan to further address servicing by 

professionals when we develop a new 

rule under section 609 of the Clean Air 

Act for servicing and maintenance of 

MVAC systems. 

Comment: Some commenters 

supported prohibiting sale of HFO– 

1234yf in small containers. Other 

commenters stated that only certified 

technicians should be allowed to 

purchase and use refrigerants, including 

HFC–134a and HFO–1234yf. Other 

commenters found no data to support 

restrictions on the sale of HFO–1234yf 

to non-professionals. 

Response: As noted previously, the 

submission only addressed unique 

fittings for large containers (e.g., 20 lbs 

or larger) of HFO–1234yf. If anyone is 

interested in using HFO–1234yf in small 

cans or other small containers, they 

would need to contact the refrigerant 

manufacturer to submit unique fittings 

for approval under the SNAP program. 

Thus, under this final rule, we believe 

that only certified technicians will 

purchase HFO–1234yf because the 

larger containers are likely to be 

prohibitively expensive for individuals 

performing DIY servicing ($800 or more 

for a 20 lb cylinder) and are likely to be 

too large for most individuals to use, 

containing enough refrigerant for 10 or 

more charges. 

We also note that in a separate final 

rule under the authority of TSCA 

(October 27, 2010; 75 FR 65987), EPA 

requires among other things, that notice 

must be given to EPA 90 days before (1) 

HFO–1234yf is used commercially other 

than in new passenger cars and vehicles 

in which the charging of motor vehicle 

air conditioning systems with HFO– 

1234yf was done by the motor vehicle 

OEM or (2) sale or distribution of 

products intended for use by a 

consumer for the purpose of servicing, 

maintenance and disposal involving 

HFO–1234yf. 

Comment: A commenter stated that 

banning DIY use of HFO–1234yf will 

mean that car owners will be forced to 

have professionals perform service work 

on their AC systems at a significantly 

higher cost. This commenter stated that 

millions of lower-income motorists may 

be forced to go without air conditioning 

each year or may seek out lower-cost 

alternatives such as propane or HFC– 

152a. 

Response: While this final rule 

effectively prohibits DIY use because 

the final use conditions do not include 

unique fittings allowing for use with 

small refrigerant containers, we are not 

making any final determination about 

whether HFO–1234yf may be safely 

used by DIYers. As we noted above, we 

have not yet received a submission for 

DIY use or received unique fittings for 

small containers from the manufacturer, 

but would evaluate such submissions 

when we receive one. We note that 

because it is unlikely that any cars will 

have MVAC systems with HFO–1234yf 

before the 2013 model year, we believe 

the availability of small containers for 

DIY use will not be of concern until 

such cars are sold and there is a need 

to recharge a new MVAC system on a 

model year 2013 vehicle. The separate 

final Significant New Use Rule that the 

Agency has issued under TSCA (75 FR 

65987; October 27, 2010) requires 

submission of a Significant New Use 

Notice at least 90 days before sale or 

distribution of products intended for 

DIY use. 

With respect to the commenter who 

suggests that some people may seek 

lower cost alternatives, presumably to 

repair an existing MVAC, we note that 

under current EPA regulations in 

appendix D to subpart G of 40 CFR part 

82, it is not legal to top-off the 


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refrigerant in an MVAC system with a 

different substitute refrigerant. 

G. Servicing Issues 

Comment: Several commenters stated 

that appropriate training and 

certification should be required to 

purchase HFO–1234yf for use in 

MVACs. Four commenters also stated 

that the final regulation should include 

a provision requiring proof of 

certification in order to purchase HFO– 

1234yf, and recommended that current 

AC systems tests (i.e., for CAA section 

609 certification) be updated. 

Some commenters disagreed with 

EPA’s statement that HFO–1234yf may 

cause serious health effects when used 

in servicing and maintaining MVACs 

without professional training. Another 

commenter stated that EPA is limiting 

productivity by only allowing 

dealerships to perform refrigerant 

maintenance, and that independent 

MVAC service shops should be allowed 

to be certified. The commenter also 

questioned who will monitor ‘‘certified’’ 

technicians employed by dealerships 

that may do work on the side. A 

commenter representing automobile 

dealerships specifically opposed 

mandatory requirements for certification 

of technicians because of potential costs 

and burden on small businesses. 

Response: As background for the 

public comments, we note that under 

EPA’s regulations implementing section 

609, one must be a section 609 certified 

technician in order to purchase CFC–12 

or other ODS for use in MVAC (40 CFR 

82.34(b)). Section 609(e) of the CAA 

itself specifically prohibits sale of small 

containers less than 20 pounds with 

Class I or Class II substances suitable for 

use as a refrigerant in MVAC, except for 

individuals performing service for 

consideration in compliance with 

section 609. However, there is no 

comparable restriction on the sale of 

HFC–134a or on other substitutes for 

MVAC that do not contain Class I or 

Class II ODS, such as HFO–1234yf. 

In the NPRM (74 FR 53449), EPA 

stated that any specific training and 

certification requirements would be 

adopted through a rulemaking under the 

authority of CAA section 609 and would 

be codified in subpart B of 40 CFR part 

82, which contains the regulations 

implementing section 609. We will 

address concerns regarding certification 

and training requirements during that 

separate rulemaking process. We note, 

however, that the CAA itself mandates 

that persons performing service for 

consideration that involve the 

refrigerant must be properly trained and 

certified. Furthermore, as noted 

previously, we believe that there is not 

a significant health risk to professionals 

from HFO–1234yf because they will 

have the knowledge and equipment to 

mitigate any risks. Also, because HFC– 

134a presents similar risks to HFO– 

1234yf, and the flammability risks of 

HFO–1234yf are less than those for 

HFC–152a, the health risks of HFO– 

1234yf are not significantly greater than 

those of other available substitutes. 

With regard to whether independent 

service shops could service MVACs 

with HFO–1234yf or whether service 

would be limited to ‘‘dealerships,’’ we 

note that neither this rule nor any other 

CAA regulation would limit servicing to 

dealerships. The comment may concern 

the withdrawn SNUR, 75 FR 4983 

(February 1, 2010), which referred to the 

‘‘original equipment manufacturer’’; the 

commenter may have interpreted this 

term to mean an automobile dealership. 

The final SNUR (October 27, 2010; 75 

FR 65987) requires a significant new use 

notice to EPA at least 90 days before 

‘‘commercial use other than in new 

passenger cars and vehicles in which 

the charging of motor vehicle air 

conditioning systems with the PMN 

substance [HFO–1234yf] was done by 

the motor vehicle original equipment 

manufacturer.’’ This requirement 

restricts commercial use of HFO–1234yf 

to use for vehicles that were initially 

charged with HFO–1234yf by the 

automobile’s manufacturer, as opposed 

to allowing commercial use of HFO– 

1234yf for vehicles initially charged 

with a different refrigerant. The term 

‘‘original equipment manufacturer’’ 

refers to the automobile manufacturer, 

not to dealerships. 

Comment: Commenters indicated that 

SAE International is developing 

standards for safety and servicing of 

alternative refrigerant HFO–1234yf 

MVAC systems. Another commenter 

stated that there are appropriate 

mechanisms within the industry for 

training. One commenter representing 

automobile dealerships objected to 

mandatory Section 609 technician 

certification and training for use of 

HFO–1234yf, stating that because 

dealerships already train technicians on 

flammable substances in accordance 

with hazard communication standards 

of the Occupational Safety and Health 

Administration (OSHA), and since the 

risks associated with HFO–1234yf are 

similar to those that already exist in 

MVAC service facilities, mandatory 

training and proof of training is not 

necessary. To enable training pursuant 

to the OSHA hazard communication 

standard, the commenter stated that 

MVAC system and refrigerant suppliers 

should provide dealerships with 

sufficient information on the hazards 

posed by HFO–1234yf. 

Response: EPA is issuing use 

conditions in this final rule that 

reference relevant SAE technical 

standards on safety. This rule does not, 

however, include a use condition 

requiring technician training and does 

not refer to specific training standards. 

We agree with the commenter that 

current technician training generally 

should be sufficient to ensure that 

professional technicians will use HFO– 

1234yf safely. Although this SNAP 

determination does not contain a use 

condition regarding technician training, 

as noted above, section 609 of the CAA 

requires technician training for persons 

servicing for consideration. EPA will 

consider in a separate rulemaking under 

section 609, whether it is necessary to 

modify our existing regulations under 

section 609 to include additional 

specifications for HFO–1234yf. 

Comment: A commenter representing 

automobile dealerships opposed 

mandatory requirements for recycling 

and containment of the refrigerant 

because of potential costs and minimal 

environmental benefits. 

Response: This rulemaking does not 

impose requirements for recycling or 

containment of the refrigerant. A 

separate rulemaking under CAA section 

609 will address practices required in 

the servicing of MVAC systems using 

HFO–1234yf, including recycling and 

recovery. Further, EPA notes that 

Section 608 of the CAA prohibits the 

intentional release of any refrigerant 

during the maintenance, repair, service, 

or disposal of refrigeration and air 

conditioning equipment, unless the 

Administrator determines through 

rulemaking that such release does not 

pose a threat to the environment. We 

have not made such a determination for 

HFO–1234yf. 

H. Cost, Availability, and Small 

Business Impacts 

Comment: One late commenter stated 

that there was insufficient information 

in the record on the cost, terms of 

availability and anticipated market 

share of HFO–1234yf for EPA to make 

the required statutory findings that 

HFO–1234yf ‘‘reduces the overall risk to 

human health and the environment’’ by 

comparison to other alternatives that are 

already available. The commenter stated 

that this information is necessary in 

order for EPA to assess anticipated 

environmental effects adequately. The 

same commenter stated that EPA’s 

environmental analysis is based on 

price assumptions that were not 

disclosed and are no longer valid, and 

thus, EPA should subpoena the 


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26The regulations for the SNAP program include 

cost and availability as one of the criteria for review 

as to whether a substitute is acceptable or 

unacceptable as a replacement for ozone depleting 

substances (82.180(a)(7)(vii)), along with a number 

of criteria for different aspects of health and 

environmental impacts. Cost and availability are 

included as criteria because they affect assumptions 

we may make about a substitute regarding its risks, 

i.e., we need to know its cost and availability so we 

can make assumptions about the risk it might pose. 

In this case, we assumed that HFO–1234yf would 

be used widely across the industry in new MVACs 

because widespread use of a single refrigerant in 

new car models has been the industry practice with 

MVAC systems. Thus, more detail on cost and 

availability of the substitute was not necessary in 

order to identify assumptions we should make for 

estimating risk. 

information from the manufacturer and 

reopen the public comment period. 

Response: EPA believes that there was 

sufficient information in the record at 

the time of proposal for us to complete 

a meaningful environmental analysis, 

even in the absence of definitive cost 

information. At the time of proposal, we 

had available both estimates from a 

trade magazine provided by the 

manufacturer (Weissler, 2008), as well 

as estimates of price provided in the 

initial submission from the 

manufacturer (EPA–HQ–OAR–2008– 

0664–0013). The estimates of price 

provided by the manufacturer were 

claimed as confidential business 

information and thus were not available 

in the record to the public. 

We typically use this type of 

information for purposes of determining 

market penetration for a particular 

substance, so that we can evaluate how 

much of the substitute will likely be 

used and thus the environmental risks 

it might pose. In this case, however, 

because the automobile industry tends 

to prefer use of a single substitute, 

information on the cost of the substitute 

was not critical to our analysis. Thus, in 

conducting our environmental analysis, 

we took a conservative approach, 

assuming that all new MVAC systems 

began using HFO–1234yf by 2020 (i.e., 

full market penetration). We also 

considered an even more conservative 

scenario, in which HFO–1234yf would 

be the only refrigerant used for 

stationary air conditioning and for 

refrigeration as of 2020, as well as for 

MVAC. Even with these highly 

conservative assumptions, we found 

that there would not be sufficient 

negative environmental impacts due to 

emissions of HFO–1234yf to warrant 

finding it unacceptable. 

In the proposal, we mentioned a cost 

estimate for HFO–1234yf of $40–$60/lb 

(Weissler, 2008). More recently, the first 

automobile manufacturer announcing 

its intention to use HFO–1234yf 

confirmed that this range does not 

underestimate prices of HFO–1234yf 

and is consistent with the 

manufacturer’s long-term purchase 

contracts (Sciance, 2010). Thus, the 

most recent information shows costs to 

be similar to those we considered at the 

time of proposal. This data contradicts 

the late commenter’s assertion that the 

manufacturer’s effective monopoly 

would result in significantly different, 

higher costs that would invalidate EPA’s 

earlier analysis. In any event, assuming 

that costs were higher as suggested by 

the commenter, then we expect that use 

of HFO–1234yf would be less than 

assumed for our health and 

environmental risk analysis. As 

mentioned in the proposal, emissions, 

and thus the resulting environmental 

effects such as impacts on local air 

quality or on production of TFA, would 

be expected to be less under a scenario 

with higher prices and less use of HFO– 

1234yf. Our analysis assumes 

widespread use and thus its results 

would be protective. 

We note that where a new chemical 

is introduced, there is some uncertainty 

in the price. At best, the manufacturer 

can provide rough estimates of price 

and of market share before the chemical 

is produced in commercial quantities 

and becomes subject to supply and 

demand pressures. EPA’s requirement 

for information on cost, anticipated 

availability in the market, and 

anticipated market share (40 CFR 

82.178(a)(14) through (16)) should not 

be construed as requiring precise, 

detailed cost estimates based upon a 

well-defined methodology. As noted 

above, we use these numbers for the 

purposes of predicting market 

penetration and thus how much of a 

particular substitute might be used and 

thus pose an environmental risk. As we 

did for HFO–1234yf, we typically take 

an environmentally-protective approach 

to our evaluation, assuming use at least 

as high as that the cost and availability 

information may indicate. 

Comment: A late commenter stated 

that the information in the record is 

insufficient for EPA to make a statutory 

finding that HFO–1234yf is ‘‘currently or 

potentially available.’’ The commenter 

stated that a previous decision by the 

United States Court of Appeals for the 

District of Columbia Circuit (Honeywell 

International, Inc. v. EPA, 374 F.3d 

1363 (D.C. Cir. 2004)) implied that an 

interpretation of the term ‘‘available’’ in 

CAA section 612(c)(2) could potentially 

consider economic factors if EPA 

adopted such an approach as a 

reasonable interpretation of the 

statutory language. The commenter 

states that EPA should obtain 

information as to the anticipated cost of 

HFO–1234yf if the manufacturer does 

not grant licenses to produce. 

Response: The CAA does not require 

that EPA find a substitute to be available 

or potentially available when finding it 

acceptable. Section 612(c) states: ‘‘* * * 

It shall be unlawful to replace any class 

I or class II substance with any 

substitute substance which the 

Administrator determines may present 

adverse effects to human health or the 

environment, where the Administrator 

has identified an alternative to such 

replacement that—reduces the overall 

risk to human health and the 

environment; and is currently or 

potentially available. * * *’’ 

This section makes clear that it is not 

the substitute under review that must be 

available or potentially available, but 

rather alternative replacements for ODS 

that EPA determines pose less overall 

risk to human health and the 

environment than the substitute being 

reviewed. Thus, if there are alternatives 

to the substance under review that are 

currently or potentially available and 

that pose less risk, EPA cannot find the 

substitute under review acceptable. 

Section 612(c) establishes no 

requirement that EPA must determine 

that the substitute under review is 

‘‘available.’’ See also 40 CFR 82.180(b) 

(describing types of listing decisions 

EPA can make in reviewing 

substitutes 26). We note that even if EPA 

was required to determine that the 

substitute under review is available or 

potentially available before it could 

make an acceptability determination, we 

believe that the available information 

supports that HFO–1234yf is potentially 

available. EPA’s definition of 

‘‘potentially available’’ at 40 CFR 82.172 

provides that ‘‘potentially available’’ is 

defined as any alternative for which 

adequate health, safety, and 

environmental data, as required for the 

SNAP notification process, exist to 

make a determination of acceptability, 

and which the Agency reasonably 

believes to be technically feasible, even 

if not all testing has yet been completed 

and the alternative is not yet produced 

or sold. This definition makes explicit 

that it is not necessary to have perfect 

information on a substitute nor is it 

necessary for the substitute to be 

produced or sold in order for EPA to 

consider it ‘‘potentially available.’’ 

Instead, it is necessary for EPA to find 

the health, safety and environmental 

data adequate to make a determination 

of acceptability, and for the Agency to 

reasonably believe that the alternative is 

‘‘technically feasible,’’ in order for the 

alternative to be potentially available. 

We believe the record contains adequate 

information showing that HFO–1234yf 


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Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011 / Rules and Regulations 17513 

is potentially available. The 

manufacturer has submitted the 

information required under 40 CFR 

82.178 (e.g., pre-manufacture notice 

form and TSCA/SNAP addendum form 

containing: Name and description of the 

substitute, physical and chemical 

information, information on ODP and 

global warming impacts, toxicity data, 

data on environmental fate and 

transport, flammability, exposure, cost 

and estimated production). The 

submitter has also provided unique 

fittings as required under appendix D to 

subpart G of 40 CFR part 82. Thus, we 

believe that there is ‘‘adequate health, 

safety, and environmental data.’’ Even if 

the commenter were correct about 

claims that higher costs would result if 

the manufacturer does not grant licenses 

for production, as discussed above, this 

does not affect the adequacy of the 

health, safety, and environmental data 

for HFO–1234yf, because we have 

protectively assumed widespread use 

that would result in more emissions and 

greater environmental impacts. In 

addition, based on the experimental 

work conducted by the automobile 

industry, we reasonably believe that 

HFO–1234yf is technically feasible as a 

refrigerant. Thus, HFO–1234yf would 

still be ‘‘potentially available’’ under the 

SNAP program’s definition. 

One commenter points to Honeywell 

International, Inc. v. EPA, 374 F.3d 

1363 in urging EPA to explicitly include 

cost as a consideration in determining 

whether a substitute is ‘‘potentially 

available.’’ In that case, the court 

vacated and remanded a SNAP decision 

in which EPA listed a foam blowing 

substitute as acceptable subject to 

‘‘narrowed use limits’’ on the basis that 

for some niche foam blowing uses, the 

substitutes that were already listed as 

acceptable might not be available. 

Under the narrowed use limits, the enduser would need to demonstrate and 

document that other substitutes were 

not technically feasible for a particular 

use. The court vacated and remanded 

EPA’s rule on the basis that EPA had 

considered cost in concluding that 

already listed substitutes might not be 

available based on ‘‘technical’’ 

feasibility, and that EPA had not 

attempted to justify the rule on the 

ground that the statute allows it to 

consider economic factors in making its 

SNAP determinations. The court left 

open the question of whether EPA could 

attempt to interpret the term ‘‘available’’ 

in section 612(c) as allowing for 

consideration of costs. 

Again, we note that ‘‘available or 

potentially available’’ applies only to the 

substitutes against which the substitute 

at issue is being compared. The Agency 

has not decided whether consideration 

of the cost of other substitutes should be 

a factor to consider in determining 

whether they are available or potentially 

available and thus should (or should 

not) be used for comparison to a 

substitute under review. However, we 

note that for purposes of the substitute 

under review, the Agency firmly 

believes that cost should not be the 

primary or sole basis for finding a 

substitute unacceptable. EPA’s role is to 

determine the health and environmental 

risk associated with the use of 

substitutes and the market should serve 

to address the issue of costs. Costs will 

necessarily be a factor considered by the 

automobile manufacturers in deciding 

which substitute to use. 

Comment: Two commenters stated 

that EPA needed to perform further 

analysis on the potential small business 

impacts and costs of EPA’s regulations 

and the introduction of HFO–1234yf. A 

commenter representing recyclers of 

automobiles and scrap metal expressed 

concern about the regulatory burden 

and costs that automotive recyclers are 

likely to incur if they must manage 

flammable refrigerants that are regulated 

as hazardous waste under EPA’s 

regulations implementing the Resource 

Conservation and Recovery Act (RCRA). 

The same commenter also suggests that 

the RCRA subtitle C regulations would 

need to be changed to alleviate the 

hazardous-waste management 

requirements for handling HFO–1234yf. 

The other commenter mentioned the 

costs to service and repair shops, endof-life vehicle recyclers, and automobile 

dealerships, and stated that EPA needed 

to analyze costs to these small 

businesses under the Regulatory 

Flexibility Act (RFA). This latter 

commenter stated that EPA should 

determine if a significant change in 

price and supply expectations would 

affect the way that these businesses 

handle and deal with automobile repairs 

and recycling. 

Response: The RFA applies only 

when there are small entities subject to 

the requirements of the proposed or 

final rule. 5 U.S.C. § 604(a)(3). We 

believe the potential burden of 

complying with RCRA regulations 

placed on those recycling or recovering 

a substitute is generally not pertinent to 

a decision of whether HFO–1234yf 

should be found acceptable under 

SNAP. To the extent the commenters are 

suggesting that we must evaluate such 

costs for purposes of the Regulatory 

Flexibility Act, we note that under the 

RFA we evaluate costs imposed by the 

enforceable regulations being 

promulgated. To the extent the costs 

referred to by the commenter are already 

imposed under RCRA, they would not 

be new costs, but costs associated with 

the relevant RCRA regulations. 

Moreover, under this SNAP final rule, 

EPA is not requiring the use of HFO– 

1234yf, and thus the costs associated 

with its use are not due to enforceable 

regulatory requirements under SNAP. 

To the extent there are enforceable 

requirements for those persons who 

choose to use this new substitute, those 

requirements (the ‘‘use conditions’’) 

apply primarily to manufacturers of 

automobiles and MVAC systems, 

because they concern design of MVAC 

systems. The one use condition of the 

rule that applies to servicing of MVAC 

systems, and thus, could apply to small 

businesses, is the requirement for 

specific unique service fittings. 

However, EPA’s existing SNAP 

regulations at appendix D to subpart G 

of 40 CFR part 82 already require 

unique service fittings as specified by 

the refrigerant manufacturer. Thus, the 

costs of purchasing new unique fittings 

for this refrigerant are imposed by the 

pre-existing regulation. This rule 

specifies the requirements for the type 

of unique fitting, in accordance with the 

fittings provided to EPA by the 

manufacturer. These fittings are part of 

the SAE J639 standard. It is not clear 

that there would be any cost differential 

between these specific unique fittings 

and others that the automotive industry 

could adopt instead. For these reasons, 

EPA is able to certify that this regulation 

will not create a significant impact on 

a significant number of small entities. 

Regulations concerning disposal of 

refrigerant from MVAC systems and 

other refrigerant-containing appliances 

under section 608 of the CAA are at 

subpart F of 40 CFR part 82. Cost and 

benefit estimates for these regulations 

are at http://www.regulations.gov, 

docket EPA–HQ–OAR–2003–0167. EPA 

notes that there may be costs of 

servicing or of disposal (end-of-life) to 

small businesses under future 

regulations under section 609 or 608 of 

the CAA. We will conduct an analysis 

of such costs, and any potential 

significant impacts on small entities, as 

necessary, as part of those future 

rulemakings. 

Comment: A commenter stated that to 

comply with requirements of the 

Unfunded Mandates Reform Act 

(UMRA), EPA needed to perform further 

analysis on the potential costs of EPA’s 

SNAP regulations for HFO–1234yf to 

determine if the rule would result in the 

expenditure of $100 million or more per 

year by the private sector. In particular, 

the commenter stated that EPA must 

obtain more information on pricing and 


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17514 Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011 / Rules and Regulations 

27As defined at 40 CFR 82.104 ‘‘interstate 

commerce’’ means the distribution or transportation 

of any product between one state, territory, 

possession or the District of Columbia, and another 

state, territory, possession or the District of 

Columbia, or the sale, use or manufacture of any 

product in more than one state, territory, possession 

or District of Columbia. The entry points for which 

a product is introduced into interstate commerce 

are the release of a product from the facility in 

which the product was manufactured, the entry into 

a warehouse from which the domestic manufacturer 

releases the product for sale or distribution, and at 

the site of United States Customs clearance. 

28As defined at 40 CFR 82.172 ‘‘end-use’’ means 

processes or classes of specific applications within 

major industrial sectors where a substitute is used 

to replace an ozone-depleting substance. 

the effect of the manufacturer’s patent to 

analyze this. 

Response: UMRA applies only to 

‘‘enforceable duties’’ imposed on State, 

local, and Tribal governments or on the 

private sector. The SNAP rule does not 

impose duties on governments. As we 

have noted previously, the SNAP 

program does not mandate the use of 

any specific substitute for ozone 

depleting substances. Rather, through 

this action, we are expanding the 

choices of MVAC refrigerants available 

to the private sector. The issue raised by 

the commenter concerning the cost of 

the refrigerant and the effect of the 

manufacturer’s patent on pricing is not 

related to any requirement of the rule, 

and thus, EPA is not required to 

consider that cost under UMRA. 

VIII. How does the SNAP program 

work? 

A. What are the statutory requirements 

and authority for the SNAP program? 

Section 612 of the Clean Air Act 

(CAA) requires EPA to develop a 

program for evaluating alternatives to 

ozone-depleting substances (ODS). EPA 

refers to this program as the Significant 

New Alternatives Policy (SNAP) 

program. The major provisions of 

section 612 are: 

1. Rulemaking 

Section 612(c) requires EPA to 

promulgate rules making it unlawful to 

replace any class I (i.e., 

chlorofluorocarbon, halon, carbon 

tetrachloride, methyl chloroform, 

methyl bromide, and 

hydrobromofluorocarbon) or class II 

(i.e., hydrochlorofluorocarbon) 

substance with any substitute that the 

Administrator determines may present 

adverse effects to human health or the 

environment where the Administrator 

has identified an alternative that (1) 

reduces the overall risk to human health 

and the environment, and (2) is 

currently or potentially available. 

2. Listing of Unacceptable/Acceptable 

Substitutes 

Section 612(c) requires EPA to 

publish a list of the substitutes 

unacceptable for specific uses and to 

publish a corresponding list of 

acceptable alternatives for specific uses. 

The list of acceptable substitutes is 

found at http://www.epa.gov/ozone/ 

snap/lists/index.html and the lists of 

‘‘unacceptable’’, ‘‘acceptable subject to 

use conditions’’, and ‘‘acceptable subject 

to narrowed use limits’’ substitutes are 

found at subpart G of 40 CFR part 82. 

3. Petition Process 

Section 612(d) grants the right to any 

person to petition EPA to add a 

substance to, or delete a substance from, 

the lists published in accordance with 

section 612(c). The Agency has 90 days 

to grant or deny a petition. Where the 

Agency grants the petition, EPA must 

publish the revised lists within an 

additional six months. 

4. 90-Day Notification 

Section 612(e) directs EPA to require 

any person who produces a chemical 

substitute for a class I substance to 

notify the Agency not less than 90 days 

before new or existing chemicals are 

introduced into interstate commerce for 

significant new uses as substitutes for a 

class I substance. The producer must 

also provide the Agency with the 

producer’s unpublished health and 

safety studies on such substitutes. 

5. Outreach 

Section 612(b)(1) states that the 

Administrator shall seek to maximize 

the use of Federal research facilities and 

resources to assist users of class I and 

II substances in identifying and 

developing alternatives to the use of 

such substances in key commercial 

applications. 

6. Clearinghouse 

Section 612(b)(4) requires the Agency 

to set up a public clearinghouse of 

alternative chemicals, product 

substitutes, and alternative 

manufacturing processes that are 

available for products and 

manufacturing processes which use 

class I and II substances. 

B. What are EPA’s regulations 

implementing section 612? 

On March 18, 1994, EPA published 

the original rulemaking (59 FR 13044) 

which established the process for 

administering the SNAP program and 

issued EPA’s first lists identifying 

acceptable and unacceptable substitutes 

in the major industrial use sectors 

(subpart G of 40 CFR part 82). These 

sectors include: Refrigeration and air 

conditioning; foam blowing; cleaning 

solvents; fire suppression and explosion 

protection; sterilants; aerosols; 

adhesives, coatings and inks; and 

tobacco expansion. These sectors 

compose the principal industrial sectors 

that historically consumed the largest 

volumes of ODS. 

Section 612 of the CAA requires EPA 

to list as acceptable only those 

substitutes that do not present a 

significantly greater risk to human 

health and the environment as 

compared with other substitutes that are 

currently or potentially available. 

C. How do the regulations for the SNAP 

program work? 

Under the SNAP regulations, anyone 

who plans to market or produce a 

substitute to replace a class I or II ODS 

in one of the eight major industrial use 

sectors must provide notice to the 

Agency, including health and safety 

information on the substitute at least 90 

days before introducing it into interstate 

commerce for significant new use as an 

alternative. This requirement applies to 

the person planning to introduce the 

substitute into interstate commerce,27

typically chemical manufacturers, but 

may also include importers, 

formulators, equipment manufacturers, 

or end-users 28 when they are 

responsible for introducing a substitute 

into commerce. 

The Agency has identified four 

possible decision categories for 

substitutes: acceptable; acceptable 

subject to use conditions; acceptable 

subject to narrowed use limits; and 

unacceptable. Use conditions and 

narrowed use limits are both considered 

‘‘use restrictions’’ and are explained 

below. Substitutes that are deemed 

acceptable with no use restrictions (no 

use conditions or narrowed use limits) 

can be used for all applications within 

the relevant end-uses within the sector. 

Substitutes that are acceptable subject to 

use restrictions may be used only in 

accordance with those restrictions. It is 

illegal to replace an ODS with a 

substitute listed as unacceptable, unless 

certain exceptions (e.g., test marketing, 

research and development) provided by 

the regulation are met. 

After reviewing a substitute, the 

Agency may determine that a substitute 

is acceptable only if certain conditions 

in the way that the substitute is used are 

met to minimize risks to human health 

and the environment. EPA describes 

such substitutes as ‘‘acceptable subject 

to use conditions.’’ Entities that use 

these substitutes without meeting the 


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Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011 / Rules and Regulations 17515 

associated use conditions are in 

violation of section 612 of the Clean Air 

Act and EPA’s SNAP regulations. 

For some substitutes, the Agency may 

permit a narrowed range of use within 

an end-use or sector. For example, the 

Agency may limit the use of a substitute 

to certain end-uses or specific 

applications within an industry sector. 

The Agency requires a user of a 

narrowed use substitute to demonstrate 

that no other acceptable substitutes are 

available for their specific application 

by conducting comprehensive studies. 

EPA describes these substitutes as 

‘‘acceptable subject to narrowed use 

limits.’’ A person using a substitute that 

is acceptable subject to narrowed use 

limits in applications and end-uses that 

are not consistent with the narrowed 

use limit is using the substitute in an 

unacceptable manner and is in violation 

of section 612 of the CAA and EPA’s 

SNAP regulations. 

The Agency publishes its SNAP 

program decisions in the Federal 

Register (FR). EPA publishes decisions 

concerning substitutes that are deemed 

acceptable subject to use restrictions 

(use conditions and/or narrowed use 

limits), or for substitutes deemed 

unacceptable, as proposed rulemakings 

to allow the public opportunity to 

comment, before publishing final 

decisions. 

In contrast, EPA publishes decisions 

concerning substitutes that are deemed 

acceptable with no restrictions in 

‘‘notices of acceptability,’’ rather than as 

proposed and final rules. As described 

in the rule initially implementing the 

SNAP program (59 FR 13044), EPA does 

not believe that rulemaking procedures 

are necessary to list alternatives that are 

acceptable without restrictions because 

such listings neither impose any 

sanction nor prevent anyone from using 

a substitute. 

Many SNAP listings include 

‘‘comments’’ or ‘‘further information’’ to 

provide additional information on 

substitutes. Since this additional 

information is not part of the regulatory 

decision, these statements are not 

binding for use of the substitute under 

the SNAP program. However, regulatory 

requirements so listed are binding under 

other regulatory programs. The ‘‘further 

information’’ classification does not 

necessarily include all other legal 

obligations pertaining to the use of the 

substitute. While the items listed are not 

legally binding under the SNAP 

program, EPA encourages users of 

substitutes to apply all statements in the 

‘‘further information’’ column in their 

use of these substitutes. In many 

instances, the information simply refers 

to sound operating practices that have 

already been identified in existing 

industry and/or building-codes or 

standards. Thus, many of the 

statements, if adopted, would not 

require the affected user to make 

significant changes in existing operating 

practices. 

D. Where can I get additional 

information about the SNAP program? 

For copies of the comprehensive 

SNAP lists of substitutes or additional 

information on SNAP, refer to EPA’s 

Ozone Depletion Web site at http:// 

www.epa.gov/ozone/snap/index.html. 

For more information on the Agency’s 

process for administering the SNAP 

program or criteria for evaluation of 

substitutes, refer to the SNAP final 

rulemaking published March 18, 1994 

(59 FR 13044), codified at subpart G of 

40 CFR part 82. A complete chronology 

of SNAP decisions and the appropriate 

citations are found at http:// 

www.epa.gov/ozone/snap/chron.html. 

IX. Statutory and Executive Order 

Reviews 

A. Executive Order 12866: Regulatory 

Planning and Review 

Under Executive Order (EO) 12866 

(58 FR 51735, October 4, 1993), this 

action is a ‘‘significant regulatory 

action.’’ It raises novel legal or policy 

issues arising out of legal mandates, the 

President’s priorities, or the principles 

set forth in the Executive Order. 

Accordingly, EPA submitted this 

action to the Office of Management and 

Budget (OMB) for review under EO 

12866 and any changes made in 

response to OMB recommendations 

have been documented in the docket for 

this action. 

B. Paperwork Reduction Act 

This action does not impose any new 

information collection burden. Today’s 

action is an Agency determination. It 

contains no new requirements for 

reporting. The only new recordkeeping 

requirement involves customary 

business practice. Today’s rule requires 

minimal record-keeping of studies done 

to ensure that MVAC systems using 

HFO–1234yf meet the requirements set 

forth in this rule. Because it is 

customary business practice that OEMs 

conduct and keep on file Failure Mode 

and Effect Analysis (FMEA) on any 

potentially hazardous part or system 

from the beginning of production of a 

car model until three or more years after 

production of the model ends, we 

believe this requirement will not impose 

an additional paperwork burden. 

However, the Office of Management and 

Budget (OMB) has previously approved 

the information collection requirements 

contained in the existing regulations in 

subpart G of 40 CFR part 82 under the 

provisions of the Paperwork Reduction 

Act, 44 U.S.C. 3501 et seq. and has 

assigned OMB control numbers 2060– 

0226. The OMB control numbers for 

EPA’s regulations are listed in 40 CFR 

Part 9. 

C. Regulatory Flexibility Act 

The Regulatory Flexibility Act (RFA) 

generally requires an agency to prepare 

a regulatory flexibility analysis of any 

rule subject to notice and comment 

rulemaking requirements under the 

Administrative Procedure Act or any 

other statute unless the agency certifies 

that the rule will not have a significant 

economic impact on a substantial 

number of small entities. Small entities 

include small businesses, small 

organizations, and small governmental 

jurisdictions. 

For purposes of assessing the impacts 

of today’s rule on small entities, small 

entity is defined as: (1) A small business 

as defined by the Small Business 

Administration’s (SBA) regulations at 13 

CFR 121.201; for NAICS code 336111 

(Automobile manufacturing), a small 

business has < 1000 employees; for 

NAICS code 336391 (Motor Vehicle AirConditioning Manufacturing), a small 

business has < 750 employees; (2) a 

small governmental jurisdiction that is a 

government of a city, county, town, 

school district or special district with a 

population of less than 50,000; and (3) 

a small organization that is any not-forprofit enterprise which is independently 

owned and operated and is not 

dominant in its field. 

After considering the economic 

impacts of today’s final rule on small 

entities, I certify that this action will not 

have a significant adverse economic 

impact on a substantial number of small 

entities. The only new requirement on 

small entities in this final rule is a 

requirement specifying the type of 

unique service fittings required when 

servicing MVAC systems using the 

refrigerant HFO–1234yf. Existing 

regulations at appendix D to subpart G 

of 40 CFR part 82 already require that 

there be unique service fittings for each 

refrigerant used in MVAC systems. 

Thus, the costs of purchasing new 

unique fittings for this refrigerant have 

already been imposed by the preexisting regulation. This rule specifies 

the requirements for which type of 

unique fitting, in accordance with the 

fittings provided to EPA by the 

manufacturer. These fittings are part of 

the SAE J639 standard. It is not clear 

that there would be any cost differential 

between these specific unique fittings 


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17516 Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011 / Rules and Regulations 

and others that the automotive industry 

could adopt instead. Thus, cost impacts 

of this final rule on small entities are 

expected to be small. This final rule is 

expected to relieve burden for some 

small entities, such as car repair shops, 

by allowing them the flexibility to use 

a new refrigerant that otherwise would 

have been prohibited under previous 

requirements at appendix B to subpart 

G of 40 CFR part 82 and by allowing 

them to use the easy-to-use ‘‘quickconnect’’ fittings for this refrigerant. 

Other final rule requirements apply to 

original equipment manufacturers, 

which are not small entities. These final 

rule requirements are the least 

burdensome option for regulation. 

Original equipment manufacturers are 

not mandated to move to MVAC 

systems using HFO–1234yf. EPA is 

simply listing HFO–1234yf as an 

acceptable alternative with use 

conditions in new MVAC systems. This 

rule allows the use of this alternative to 

ozone-depleting substances in the 

MVAC sector and outlines the 

conditions necessary for safe use. By 

approving this refrigerant under SNAP, 

EPA provides additional choice to the 

automotive industry which, if adopted, 

would reduce the impact of MVACs on 

the global environment. This 

rulemaking does not mandate the use of 

HFO–1234yf as a refrigerant in new 

MVACs. 

D. Unfunded Mandates Reform Act 

Title II of the Unfunded Mandates 

Reform Act of 1995 (UMRA), Public 

Law 104–4, establishes requirements for 

Federal agencies to assess the effects of 

their regulatory actions on State, local, 

and Tribal governments and the private 

sector. Under section 202 of the UMRA, 

EPA generally must prepare a written 

statement, including a cost-benefit 

analysis, for proposed and final rules 

with ‘‘Federal mandates’’ that may result 

in expenditures to State, local, and 

Tribal governments, in the aggregate, or 

to the private sector, of $100 million or 

more in any one year. Before 

promulgating an EPA rule for which a 

written statement is needed, section 205 

of the UMRA generally requires EPA to 

identify and consider a reasonable 

number of regulatory alternatives and 

adopt the least costly, most costeffective or least burdensome alternative 

that achieves the objectives of the rule. 

The provisions of section 205 do not 

apply when they are inconsistent with 

applicable law. Moreover, section 205 

allows EPA to adopt an alternative other 

than the least costly, most cost-effective 

or least burdensome alternative if the 

Administrator publishes with the final 

rule an explanation why that alternative 

was not adopted. Before EPA establishes 

any regulatory requirements that may 

significantly or uniquely affect small 

governments, including Tribal 

governments, it must have developed 

under section 203 of the UMRA a small 

government agency plan. The plan must 

provide for notifying potentially 

affected small governments, enabling 

officials of affected small governments 

to have meaningful and timely input in 

the development of EPA regulatory 

proposals with significant Federal 

intergovernmental mandates, and 

informing, educating, and advising 

small governments on compliance with 

the regulatory requirements. 

EPA has determined that this rule 

does not contain a Federal mandate that 

may result in expenditures of $100 

million or more for State, local, and 

Tribal governments, in the aggregate, or 

the private sector in any one year. 

Today’s rule does not affect State, local, 

or Tribal governments. The enforceable 

requirements of today’s rule related to 

system design and documentation of the 

safety of alternative MVAC systems 

affect only a small number of original 

equipment manufacturers. Further, 

those requirements are consistent with 

requirements that the automotive 

industry has already adopted through 

consensus standards of SAE 

International. We expect that most 

manufacturers of automobiles and 

MVAC systems would attempt to meet 

those requirements or something very 

similar, even in the absence of EPA’s 

regulations. The only requirement that 

is applied more widely than for original 

equipment manufacturers is a 

requirement specifying the type of 

unique service fittings required when 

servicing MVAC systems using the 

refrigerant HFO–1234yf. Existing 

regulations at appendix D to subpart G 

of 40 CFR part 82 already require that 

there be unique service fittings for each 

refrigerant used in MVAC systems. The 

fittings required in this final rule are 

part of the SAE J639 standard. Thus, the 

costs of this rule are consistent with 

standard industry practice and are 

expected to be much less than $100 

million per year. 

This action provides additional 

options allowing greater flexibility for 

industry in designing consumer 

products. The impact of this rule on the 

private sector will be less than $100 

million per year. Thus, today’s rule is 

not subject to the requirements of 

sections 202 and 205 of the UMRA. EPA 

has determined that this rule contains 

no regulatory requirements that might 

significantly or uniquely affect small 

governments. This regulation applies 

directly to facilities that use these 

substances and not to governmental 

entities. This rule does not mandate a 

switch to HFO–1234yf and the limited 

direct economic impact on entities from 

this rulemaking is less than $100 

million annually. 

E. Executive Order 13132: Federalism 

Executive Order 13132, entitled 

‘‘Federalism’’ (64 FR 43255, August 10, 

1999), requires EPA to develop an 

accountable process to ensure 

‘‘meaningful and timely input by State 

and local officials in the development of 

regulatory policies that have federalism 

implications.’’ ‘‘Policies that have 

federalism implications’’ is defined in 

the Executive Order to include 

regulations that have ‘‘substantial direct 

effects on the States, on the relationship 

between the national government and 

the States, or on the distribution of 

power and responsibilities among the 

various levels of government.’’ 

This action does not have federalism 

implications. It will not have substantial 

direct effects on the States, on the 

relationship between the national 

government and the States, or on the 

distribution of power and 

responsibilities among the various 

levels of government, as specified in 

Executive Order 13132. This regulation 

applies directly to facilities that use 

these substances and not to 

governmental entities. Thus, Executive 

Order 13132 does not apply to this rule. 

F. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

Executive Order 13175, entitled 

‘‘Consultation and Coordination with 

Indian Tribal Governments’’ (59 FR 

22951, November 6, 2000), requires EPA 

to develop an accountable process to 

ensure ‘‘meaningful and timely input by 

tribal officials in the development of 

regulatory policies that have tribal 

implications.’’ This final rule does not 

have Tribal implications, as specified in 

Executive Order 13175. It does not 

significantly or uniquely affect the 

communities of Indian Tribal 

governments, because this regulation 

applies directly to facilities that use 

these substances and not to 

governmental entities. Thus, Executive 

Order 13175 does not apply to this rule. 

G. Executive Order 13045: Protection of 

Children From Environmental Health 

Risks and Safety Risks 

This action is not subject to EO 13045 

(62 FR 19885, April 23, 1997) because 

it is not economically significant as 

defined in EO 12866, and because the 

Agency does not believe the 

environmental health or safety risks 


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Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011 / Rules and Regulations 17517 

addressed by this action present a 

disproportionate risk to children. This 

action’s health and risk assessments are 

discussed in sections V and VII.D of the 

preamble and in documents EPA–HQ– 

OAR–2008–0664–0036 and HQ–OAR– 

2008–0664–0038 in the docket for this 

rulemaking. 

H. Executive Order 13211: Actions 

Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution, or Use 

This action is not a ‘‘significant energy 

action’’ as defined in Executive Order 

13211 (66 FR 28355 (May 22, 2001)), 

because it is not likely to have a 

significant adverse effect on the supply, 

distribution, or use of energy. This 

action could impact manufacturing and 

repair of MVAC systems using an 

alternative refrigerant. This rule does 

not mandate a switch to HFO–1234yf. 

Preliminary information indicates that 

these new systems are more energy 

efficient than currently available 

systems in some climates. Therefore, we 

conclude that this rule is not likely to 

have a significant adverse effect on 

energy supply, distribution or use. 

I. National Technology Transfer and 

Advancement Act 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (‘‘NTTAA’’), Public Law 

104–113, 12(d) (15 U.S.C. 272 note) 

directs EPA to use voluntary consensus 

standards in its regulatory activities 

unless to do so would be inconsistent 

with applicable law or otherwise 

impractical. Voluntary consensus 

standards are technical standards (e.g., 

materials specifications, test methods, 

sampling procedures, and business 

practices) that are developed or adopted 

by voluntary consensus standards 

bodies. NTTAA directs EPA to provide 

Congress, through OMB, explanations 

when the Agency decides not to use 

available and applicable voluntary 

consensus standards. 

This rulemaking involves technical 

standards. EPA has decided to use SAE 

International’s most recent version of 

the SAE J1739 and SAE J639 standards. 

These standards can be obtained from 

http://www.sae.org/technical/

standards/. These standards address 

safety and reliability issues in motor 

vehicle design, including MVAC 

systems using alternative refrigerants. 

J. Executive Order 12898: Federal 

Actions To Address Environmental 

Justice in Minority Populations and 

Low-Income Populations 

Executive Order (EO) 12898 (59 FR 

7629 (Feb. 16, 1994)) establishes Federal 

executive policy on environmental 

justice. Its main provision directs 

Federal agencies, to the greatest extent 

practicable and permitted by law, to 

make environmental justice part of their 

mission by identifying and addressing, 

as appropriate, disproportionately high 

and adverse human health or 

environmental effects of their programs, 

policies, and activities on minority 

populations and low-income 

populations in the United States. 

EPA has determined that this final 

rule will not have disproportionately 

high and adverse human health or 

environmental effects on minority or 

low-income populations because it 

increases the level of environmental 

protection for all affected populations 

without having any disproportionately 

high and adverse human health or 

environmental effects on any 

population, including any minority or 

low-income population. HFO–1234yf is 

a non-ozone-depleting substance with a 

low GWP. Based on the toxicological 

and atmospheric work described earlier, 

HFO–1234yf will not have any 

disproportionately high and adverse 

human health or environmental effects 

on any population, including any 

minority or low-income population. 

This final rule requires specific use 

conditions for MVAC systems, if car 

manufacturers chose to make MVAC 

systems using this low GWP refrigerant 

alternative. 

K. Congressional Review Act 

The Congressional Review Act, 5 

U.S.C. 801 et seq., as added by the Small 

Business Regulatory Enforcement 

Fairness Act of 1996, generally provides 

that before a rule may take effect, the 

agency promulgating the rule must 

submit a rule report, which includes a 

copy of the rule, to each House of the 

Congress and to the Comptroller General 

of the United States. EPA will submit a 

report containing this rule and other 

required information to the U.S. Senate, 

the U.S. House of Representatives, and 

the Comptroller General of the United 

States prior to publication of the rule in 

the Federal Register. A Major rule 

cannot take effect until 60 days after it 

is published in the Federal Register. 

This action is not a ‘‘major rule’’ as 

defined by 5 U.S.C. 804(2). This rule 

will be effective May 31, 2011. 

X. References 

The documents below are referenced 

in the preamble. All documents are 

located in the Air Docket at the address 

listed in section titled ADDRESSES at the 

beginning of this document. Unless 

specified otherwise, all documents are 

available in Docket ID No. EPA–HQ– 

OAR–2008–0664 at http:// 

www.regulations.gov. 

Benesch et al., 2002. Investigation of Effects 

of Trifluoroacetate on Vernal Pool 

Ecosystems. Environ. Tox and Chem. 

Vol. 21, No. 3 pp. 640–647. 2002. 

Available online at http://www3.

interscience.wiley.com/journal/

122678081/abstract?CRETRY=1&

SRETRY=0. 

Benouali et al., 2008. ‘‘A/C System Control 

Strategies for Major Refrigerant Options’’ 

June 11, 2008, Alternative Refrigerant 

Systems Symposium Phoenix, AZ. 

Available online at http://www2.dupont.

com/Refrigerants/en_US/assets/

downloads/SmartAutoAC/2008_SAE_

ARSS_Valeo_Eval.pdf. 

Besnard, S., 1996. Full Flammability Test of 

Gases and Gas Mixtures in Air. CERN. 

European Organization for Nuclear 

Research. 1996. Available online at 

http://cdsweb.cern.ch/record/1217583/

files/CM-P00055900.pdf. 

Boutonnet et al., 1999. ‘‘Environmental Risk 

Assessment of Trifluoroacetic Acid,’’ 

Human and Ecological Risk Assessment, 

Feb. 1999. Available online at http://

www.informaworld.com/smpp/content∼

db=all∼content=a922749285∼frm=

abslink. 

CARB, 2008. Technical Support Document 

‘‘Staff Analysis on Emissions and 

Economic Impact of Proposed Regulation 

for Small Containers of Automotive 

Refrigerant.’’ Appendix G to Certification 

Procedures for Small Containers of 

Automotive Refrigerant. California Air 

Resources Board, effective March 10, 

2010. Document incorporated by 

reference in California Code of 

Regulations (CCR), title 17, sections 

95360 through 95370. Available online at 

http://www.arb.ca.gov/regact/2009/

hfc09/hfc09.htm. 

Carter, 2009. Investigation of Atmospheric 

Ozone Impacts of 2,3,3,3- 

Tetrafluoropropene. Final report to 

Honeywell International Contract UCR– 

09010016. William Carter, University of 

California, Riverside CA. June 2, 2009. 

Available online at http://www.cert.ucr.

edu/%7Ecarter/pubs/YFrept.pdf. 

Ceviz and Yuksel, 2005. ‘‘Cyclic variations on 

LPG and gasoline-fuelled lean burn SI 

engine.’’ Renewable Energy. In press. 

Available online at http://www.pmkbase.com/articles/LPGsdarticle(8).pdf. 

Clodic et al., 2008. Evaluation of the 

Potential Impact of Emissions of HFC– 

134a From Non Professional Servicing of 

Motor Vehicle Air Conditioning Systems. 

D. Clodic, A. Tremoulet, Y, Riachi, D. 

Sousa, L. Palandre, A. Garnier, S. Clodic 

and M. Lansard. Prepared under CARB 

Agreement No. 06–341. December, 2008. 

Available online at http://www.arb.ca.

gov/research/apr/past/06-341.pdf. 

CRP, 2008. Risk Assessment for Alternative 

Refrigerants HFO–1234yf Phase II. 

Prepared for SAE International 

Cooperative Research Program 1234 by 

Gradient Corporation. February 26, 2008. 

Docket number EPA–HQ–OAR–2008– 

0664–0008. 


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CRP, 2009. Risk Assessment for Alternative 

Refrigerants HFO–1234yf and R–744 

(CO2) Phase III. Prepared for SAE 

International Cooperative Research 

Program 1234 by T. Lewandowski, 

Gradient Corporation. December 17, 

2009. Docket number EPA–HQ–OAR– 

2008–0664–0056.2. 

DuPont, 2008. DuPont internal testing. Cited 

in docket number EPA–HQ–OAR–2008– 

0664–0052.1. 

Hamner Institutes, 2007. Toxicogenomic 

assessment of the carcinogenic potential 

of 2,3,3,3-tetrafluoropropene. The 

Hamner Institutes for Health Sciences. 

January 5, 2007. Docket numbers EPA– 

HQ–OAR–2008–0664–0030 through 

–0030.6. 

Honeywell, 2010a. Comment on EPA 

Proposed Rule (simulated vehicle service 

leak testing and exposure study). Docket 

ID: EPA–HQ–OPPT–2008–0918–0088. 

Honeywell, 2010b. Response to EPA 

questions. Docket ID: EPA–HQ–OPPT– 

2008–0918–0096. 

ICF, 2008. ICF International. 2008. Air 

Conditioning Refrigerant Charge Size to 

Passenger Compartment Volume Ratio 

Analysis. Docket number EPA–HQ– 

OAR–2008–0664–0003. 

ICF, 2009. ICF International. 2009. Revised 

Final Draft Assessment of the Potential 

Impacts of HFO–1234yf and the 

Associated Production of TFA on 

Aquatic Communities and Local Air 

Quality. Docket number EPA–HQ–OAR– 

2008–0664–0037. 

ICF, 2010a. ICF International. 2010. 

Summary of HFO–1234yf Emissions 

Assumptions. 

ICF, 2010b. ICF International. 2010. Revised 

Assessment of the Potential Impacts of 

HFO–1234yf and the Associated 

Production of TFA on Aquatic 

Communities, Soil and Plants, and Local 

Air Quality. 

ICF, 2010c. ICF International. 2010. 

Sensitivity Analysis CMAQ results on 

projected maximum TFA rainwater 

concentrations and maximum 8-hr ozone 

concentrations. 

ICF, 2010d. ICF International. 2010. Analysis 

of Potential Impacts of Aldehydes as 

Breakdown Products from HFO–1234yf. 

ICF, 2010e. ICF International. 2010. 

Summary of Updates to the Vintaging 

Model that Impacted HFO–1234yf 

Emissions Estimates. 

IPCC, 2007. Contribution of Working Group 

I to the Fourth Assessment Report of the 

Intergovernmental Panel on Climate 

Change, 2007. 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. Available online at http://www.

ipcc.ch/publications_and_data/ar4/wg1/

en/contents.html. 

JAMA, 2008. ‘‘LCCP Result from JAMA,’’ 

Japan Automobile Manufacturers 

Association, T. Ikegami; K. Inui; K. Aoki. 

VDA Alternative Refrigerant Winter 

Meeting, Saalfelden, Austria, February 

13–14, 2008. Available online at http:// 

www.vda-wintermeeting.de/fileadmin/

downloads2008/presentations/Tohru_

Ikegami_Toyota_Kenta_Aoki_Nissan_

JAMA.pdf. (begins, p. 23). 

JAMA–JAPIA, 2008. ‘‘New Refrigerants 

Evaluation Results’’ Japan Automobile 

Manufacturers Association-Japan Auto 

Parts Industries Association Consortium. 

T. Ikegami, M. Iguchi, K. Aoki, K. Iijima; 

VDA Alternative Refrigerant Winter 

Meeting, Saalfelden, Austria, February 

13–14, 2008. Available online at http:// 

www.vda-wintermeeting.de/fileadmin/

downloads2008/presentations/Tohru_

Ikegami_Toyota_Kenta_Aoki_Nissan_

JAMA.pdf. 

Kajihara et al., 2010. ‘‘Estimation of 

environmental concentrations and 

deposition fluxes of R–1234–YF and its 

decomposition products emitted from air 

conditioning equipment to atmosphere’’. 

H. Kajihara, K. Inoue, K. Yoshida, R. 

Nagaosa. February 17–19, 2010. 2010 

International Symposium on Nextgeneration Air Conditioning and 

Refrigeration Technology. Docket 

number EPA–HQ–OAR–2008–0664– 

0114.1. 

Kirkland et al. (2005) Evaluation of a battery 

of three in vitro genotoxicity tests to 

determine rodent carcinogens and noncarcinogens. I. Sensitivity, specificity 

and relative predictivity, Mutation 

Research, 584, 1–256. Available online at 

http://www.sciencedirect.com. 

Luecken et al., 2009. Luecken, D.J., 

Waterland, R.L., Papasavva, S., 

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Degradation of 2,3,3,3- 

Tetrafluoropropene (HFO–1234yf), A 

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publication. Docket number EPA–HQ– 

OAR–2008–0664–0112.3. 

Meyer, 2008. ‘‘R–1234yf System 

Enhancements and Comparison to 

R–134a.’’ 2008, Alternative Refrigerant 

Systems Symposium Phoenix, AZ 

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com/Refrigerants/en_US/assets/

downloads/SmartAutoAC/2008_SAE_

ARSS_Visteon_Eval.pdf. 

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about alternative refrigerant evaluation’’ 

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2008_SAE_ARSS_Renault_Fiat_PSA_

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M.D., Wallington, T.J., Singh, R. 2007. 

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reactions with Cl atoms, OH radicals, 

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for Selected Airborne Chemicals: Volume 

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reactions of OH with HFC–245cb 

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potentials. V. Papadimitriou, R Talukdar, 

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2007, Vol. 9, p. 1–13. Docket number 

EPA–HQ–OAR–2008–0664–0002. 

Available online at http://pubs.rsc.org/

en/Content/ArticleLanding/2008/CP/

b714382f. 

Papasavva et al., 2009. Estimated 2017 

Refrigerant Emissions of 2,3,3,3- 

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2009. 43 pp. 9252–9259. Docket number 

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HQ–OAR–2008–0664–0138. 


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Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011 / Rules and Regulations 17519 

Spatz, 2008. Spatz, M and B. Minor 2008 

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inhalation toxicity study with HFO– 

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on SAE J1739. August 16, 2010. 

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(HFOs).’’ T. Wallington, M. Andersen, O. 

Nielsen. Atmospheric Environment. 

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0664–0084.2. Available online at http:// 

www.sciencedirect.com or at 

doi:10.1016/j.atmosenv.2010.01.040. 

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0664–0006. 

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Study of [name redacted] and HFO– 

1234yf in Dogs. WIL Laboratories, 2006. 

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0664–0019 and attachments –0019.1 

through –0019.2. 

List of Subjects in 40 CFR Part 82 

Environmental protection, 

Administrative practice and procedure, 

Air pollution control, Incorporation by 

reference, Reporting and recordkeeping 

requirements, Stratospheric ozone layer. 

Dated: February 24, 2011. 

Lisa P. Jackson, 

Administrator. 

For the reasons set out in the 

preamble, 40 CFR part 82 is amended as 

follows: 

PART 82—PROTECTION OF 

STRATOSPHERIC OZONE 

■ 1. The authority citation for part 82 

continues to read as follows: 

Authority: 42 U.S.C. 7414, 7601, 7671– 

7671q. 

Subpart G—Significant New 

Alternatives Policy Program 

■ 2. Appendix B to Subpart G of Part 82 

is amended as follows: 

■ a. By adding one new entry to the end 

and by adding a note at the end of the 

first table. 

■ b. By revising the entry for ‘‘CFC–12 

Motor Vehicle Air Conditioners (Retrofit 

and New Equipment/NIKs)’’ in the table 

titled ‘‘Refrigerants—Unacceptable 

Substitutes’’. 

The additions and revisions read as 

follows: 

Appendix B to Subpart G of Part 82— 

Substitutes Subject to Use Restrictions 

and Unacceptable Substitutes 


Emcdonald on DSK2BSOYB1PROD with RULES2
17520 Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011 / Rules and Regulations 

REFRIGERANTS—ACCEPTABLE SUBJECT TO USE CONDITIONS

Application Substitute Decision Conditions Comments 

*******

CFC–12 Automobile 

Motor Vehicle Air 

Conditioning (New 

equipment in passenger cars and 

light-duty trucks 

only).

HFO–1234yf as a 

substitute for CFC– 

12.

Acceptable subject to 

use conditions.

Manufacturers must adhere to all of the safety requirements listed in the Society of 

Automotive Engineers (SAE) Standard 

J639 (adopted 2011), including requirements for: unique fittings, flammable refrigerant warning label, high-pressure compressor cutoff switch and pressure relief 

devices. For connections with refrigerant 

containers of 20 lbs or greater, use fittings 

consistent with SAE J2844.

Additional training for 

service technicians 

recommended. 

Observe requirements 

of Significant New 

Use Rule at 40 

CFR 721.10182. 

HFO–1234yf is also 

known as 2,3,3,3- 

tetrafluoro-prop-1- 

ene (CAS No 754– 

12–1). 

Manufacturers must conduct Failure Mode 

and Effect Analysis (FMEA) as provided in 

SAE J1739 (adopted 2009). Manufacturers 

must keep the FMEA on file for at least 

three years from the date of creation.

* * * * * 

Note: The use conditions in this appendix 

contain references to certain standards from 

SAE International. The standards are 

incorporated by reference and the referenced 

sections are made part of the regulations in 

part 82: 

1. SAE J639. Safety Standards for Motor 

Vehicle Refrigerant Vapor Compression 

Systems. February 2011 edition. SAE 

International. 

2. SAE J1739. Potential Failure Mode and 

Effects Analysis in Design (Design FMEA), 

Potential Failure Mode and Effects Analysis 

in Manufacturing and Assembly Processes 

(Process FMEA). January 2009 edition. SAE 

International. 

3. SAE J2844. R–1234yf (HFO–1234yf) New 

Refrigerant Purity and Container 

Requirements for Use in Mobile AirConditioning Systems. February 2011 

edition. SAE International. 

The Director of the Federal Register 

approves this incorporation by reference in 

accordance with 5 U.S.C. 552(a) and 1 CFR 

part 51. You may obtain a copy from SAE 

Customer Service, 400 Commonwealth Drive, 

Warrendale, PA 15096–0001 USA; e-mail: 

CustomerService@sae.org; Telephone: 1– 

877–606–7323 (U.S. and Canada only) or 1– 

724–776–4970 (outside the U.S. and Canada); 

Internet address: http://store.sae.org/ 

dlabout.htm. 

You may inspect a copy at U.S. EPA’s Air 

Docket; EPA West Building, Room 3334; 

1301 Constitution Ave., NW.; Washington, 

DC or at the National Archives and Records 

Administration (NARA). For questions 

regarding access to these standards, the 

telephone number of EPA’s Air Docket is 

202–566–1742. For information on the 

availability of this material at NARA, call 

202–741–6030, or go to: http:// 

www.archives.gov/federal_register/ 

code_of_federal_regulations/ibr_ 

locations.html. 

* * * * * 

REFRIGERANTS—UNACCEPTABLE SUBSTITUTES

End-use Substitute Decision Comments 

*******

CFC–12 Motor Vehicle Air 

Conditioners (Retrofit and 

New Equipment/NIKs).

R–405A .............................. Unacceptable ..................... R–405A contains R–c318, a PFC, which has an extremely high GWP and lifetime. Other Substitutes 

exist which do not contain PFCs. 

Hydrocarbon Blend B ........ Unacceptable ..................... Flammability is a serious concern. Data have not been 

submitted to demonstrate it can be used safely in 

this end-use. 

Flammable Substitutes, 

other than R–152a or 

HFO–1234yf in new 

equipment.

Unacceptable ..................... The risks associated with using flammable substitutes 

(except R–152a and HFO–1234yf) in this end-use 

have not been addressed by a risk assessment. R– 

152a and HFO–1234yf may be used in new equipment with the use conditions in appendix B to this 

subpart. 

[FR Doc. 2011–6268 Filed 3–28–11; 8:45 am] 

BILLING CODE 6560–50–P 


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