Document ID: EPA-HQ-OAR-2008-0664-0240
Agency: epa
Document Type: Rule
Title: Protection of Stratospheric Ozone: New Substitute in Motor Vehicle Air Conditioning Sector Under the Significant New Alternatives Policy (SNAP) Program
Posted Date: 2011-03-29T04:00Z

[Federal Register Volume 76, Number 60 (Tuesday, March 29, 2011)]
[Rules and Regulations]
[Pages 17488-17520]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-6268]

[[Page 17487]]

Vol. 76

Tuesday,

No. 60

March 29, 2011

Part II

Environmental Protection Agency

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40 CFR Part 82

Protection of Stratospheric Ozone: New Substitute in the Motor Vehicle 
Air Conditioning Sector Under the Significant New Alternatives Policy 
(SNAP) Program; Final Rule

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

[[Page 17488]]

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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.

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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 ozone-depleting 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 
light-duty trucks. HFO-1234yf (2,3,3,3-tetrafluoroprop-1-ene), the 
refrigerant discussed in this final action, is a non-ozone-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
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                                                      Description of
           Category                NAICS code       regulated entities
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Industry......................            336111  Automobile
                                                   Manufacturing.
Industry......................            336391  Motor Vehicle Air-
                                                   Conditioning
                                                   Manufacturing.
------------------------------------------------------------------------

[[Page 17489]]

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 f[uuml]r Materialforschung und-pr[uuml]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 f[uuml]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).
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    \1\ Designates a standard from SAE International, formerly the 
Society of Automotive Engineers.
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    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

[[Page 17490]]

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 x 
10-12 occurrences per vehicle operating hour and risks of 
ignition at approximately 9 x 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).
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    \2\ Assumes 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.
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    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 [deg]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 re-opened 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)-134a\3\ (order of magnitude of 
10-12 events per vehicle operating hour). EPA previously

[[Page 17491]]

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).
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    \3\ HFC-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.
    \4\ HFC-152a is also known as 1,1-difluoroethane or, when used 
as a refrigerant, R-152a. The CAS Reg. No. is 75-37-6.
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    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.
---------------------------------------------------------------------------

    \5\ The 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)
---------------------------------------------------------------------------

    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

[[Page 17492]]

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).
---------------------------------------------------------------------------

    \6\ These 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.
    \7\ Analyzed 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).
---------------------------------------------------------------------------

    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

[[Page 17493]]

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.
---------------------------------------------------------------------------

    \8\ On 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.
---------------------------------------------------------------------------

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 time-weighted 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\
---------------------------------------------------------------------------

    \9\ This 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) 
x 1.9 (ratio of estimated human exposure/animal exposure) x \1/3\ 
(UF for animal to human extrapolation) x \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.
    \10\ This 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 short-term workplace exposure value was calculated as follows: 
51,690 ppm (animal exposure) x 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.
    \11\ For 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.
---------------------------------------------------------------------------

    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-

[[Page 17494]]

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-of-life 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 low-pressure 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

[[Page 17495]]

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.
---------------------------------------------------------------------------

    \12\ EPA 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).
---------------------------------------------------------------------------

    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 [deg]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 [deg]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.
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    \13\ The 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 x 10-12 per operating hour equates roughly to one 
event every 2 years for all drivers in the entire U.S.
---------------------------------------------------------------------------

    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

[[Page 17496]]

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 currently-
approved 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.
---------------------------------------------------------------------------

    \15\ Service for consideration means receiving something of 
worth or value to perform service, whether in money, credit, goods, 
or services.
---------------------------------------------------------------------------

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\
---------------------------------------------------------------------------

    \16\ EPA 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.
---------------------------------------------------------------------------

    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

[[Page 17497]]

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 
f[uuml]r Materialforschung und -pr[uuml]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, anti-freeze, 
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 [deg]C 
or higher for HFO-1234yf and 800 [deg]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 [deg]C (140 [deg]F) and an LFL 
of 5.3% at 100 [deg]C (212 [deg]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

[[Page 17498]]

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

[[Page 17499]]

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 
high-pressure 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.

[[Page 17500]]

    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.
---------------------------------------------------------------------------

    \17\ The 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.
    \18\ EPA has established a Reference Concentration (RfC) of 
0.005 ppm (5,000 ppt or 0.009 mg/m\3\) 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.
---------------------------------------------------------------------------

    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

[[Page 17501]]

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.
---------------------------------------------------------------------------

    \19\ Papasavva 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.
---------------------------------------------------------------------------

    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\
---------------------------------------------------------------------------

    \20\ Prepublication version of Wallington et al., 2010 (Docket 
item EPA-HQ-OAR-2008-0664-0084.2)
---------------------------------------------------------------------------

    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

[[Page 17502]]

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 (Sec.  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

[[Page 17503]]

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 HFO-1234yf, 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).
---------------------------------------------------------------------------

    \21\ Predictive 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.
---------------------------------------------------------------------------

    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 two-generation 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 
long-term 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-it-yourself (DIY) consumers. This commenter noted differences 
between the margin-of-exposure approach to

[[Page 17504]]

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-
Adverse-Effect 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

[[Page 17505]]

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 industry-modeled 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 long-term, 8-hour time-
weighted average exposure recommendation for comparison. EPA's concerns 
about DIY consumer exposure focuses on short-term 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).
---------------------------------------------------------------------------

    \23\ The 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.
    \24\ EPA has established a Reference Concentration (RfC) of 
0.005 ppm (5,000 ppt or 0.009 mg/m\3\) 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.
---------------------------------------------------------------------------

    Aldehydes, including formaldehyde and acetaldehyde, are already 
present in

[[Page 17506]]

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 (Sec.  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

[[Page 17507]]

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 x 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 f[uuml]r Materialforschung und-pr[uuml]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

[[Page 17508]]

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 [deg]C (typical of the exhaust manifold) and 700 [deg]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.
---------------------------------------------------------------------------

    \25\ An 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.
---------------------------------------------------------------------------

    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 
[deg]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 [deg]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 [deg]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 long-term 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

[[Page 17509]]

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 [deg]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 [deg]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 [deg]C. One of these tests found that 
HFO-1234yf mixed with PAG oil combusted starting at 730 [deg]C, while 
HFC-134a mixed with PAG oil ignited at 800 [deg]C and above; the other 
test observed no ignition of a blend of each refrigerant with PAG oil 
at 800 [deg]C, but both blends ignited at 900 [deg]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

[[Page 17510]]

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 end-uses (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 
worst-case 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

[[Page 17511]]

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

[[Page 17512]]

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

[[Page 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.
---------------------------------------------------------------------------

    \26\ The 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.
---------------------------------------------------------------------------

    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 end-user 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, end-of-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. 
Sec.  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

[[Page 17514]]

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.
---------------------------------------------------------------------------

    \27\ As 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.
    \28\ As 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 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

[[Page 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 
Air-Conditioning 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-for-
profit 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 pre-existing 
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

[[Page 17516]]

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 ``quick-connect'' 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 cost-effective 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

[[Page 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.pm-kbase.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.

[[Page 17518]]

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 Next-generation 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 non-
carcinogens. 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., 
Taddonio, K.N., Hutzell, W.T., Rugh, J.P., Andersen, S.O. 2009. 
Ozone and TFA Impacts in North America from the Degradation of 
2,3,3,3-Tetrafluoropropene (HFO-1234yf), A Potential Greenhouse Gas 
Replacement. Environ. Sci. Technol., submitted for 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 
Available online at http://www2.dupont.com/Refrigerants/en_US/assets/downloads/SmartAutoAC/2008_SAE_ARSS_Visteon_Eval.pdf.
Monforte et al., 2008 ``Updated situation about alternative 
refrigerant evaluation'' June 10-12, 2008, Alternative Refrigerant 
Systems Symposium Phoenix, AZ. http://www2.dupont.com/Refrigerants/en_US/assets/downloads/SmartAutoAC/2008_SAE_ARSS_Renault_Fiat_PSA_Eval.pdf.
Nielsen et al., 2007. Nielsen, O.J., Javadi, M.S., Sulbaek Andersen, 
M.P., Hurley, M.D., Wallington, T.J., Singh, R. 2007. Atmospheric 
chemistry of CF3CF=CH2: Kinetics and 
mechanisms of gas-phase reactions with Cl atoms, OH radicals, and 
O3. Chemical Physics Letters 439, 18-22. Available online 
at http://www.cogci.dk/network/OJN_174_CF3CF=CH2.pdf.
NRC, 1981. Atmosphere-Biosphere Interactions: Toward a Better 
Understanding of the Ecological Consequences of Fossil Fuel 
Combustion. Committee on the Atmosphere and the Biosphere, Board on 
Agriculture and Renewable Resources, Commission on Natural 
Resources, National Research Council. 1981. Available from NRC Press 
or online at http://www.nap.edu/catalog.php?record_id=135.
NRC, 1996. NRC Toxicity of Alternatives to Chlorofluorocarbons: HFC-
134a and HCFC-123 (1996). Available online at http://www.nap.edu/openbook.php?record_id=9268&page=29.
NRC, 2004. Acute Exposure Guideline Levels for Selected Airborne 
Chemicals: Volume 4 (2004) Board on Environmental Studies and 
Toxicology. The National Academies Press. Available online at http://www.nap.edu/openbook.php?record_id=10902&page=127#p2000a02f9960127001.
Orkin et al., 1997. Rate constants for the reactions of OH with HFC-
245cb (CH3CF2CF3) and some 
fluoroalkenes (CH2CHCF3, 
CH2CFCF3, CF2CFCF3, and 
CF2CF2), Journal of Physical Chemistry A 101 
(1997), pp. 9118-9124. Available online at http://pubs.acs.org/doi/abs/10.1021/jp971994r.
Papadimitriou et al., 2007. CF3CF=CH2 and (Z)-
CF3CF=CHF: temperature dependent OH rate coefficients and global 
warming potentials. V. Papadimitriou, R Talukdar, R. Portmann, A. 
Ravishankara and J. Burkholder. Phys. Chem. Chem. Phys., 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-tetrafluoropropene (HFC-1234yf) in the United States 
Resulting from Automobile Air Conditioning. Environ. Sci. Technol. 
2009. 43 pp. 9252-9259. Docket number EPA-HQ-OAR-2008-0664-0112.1. 
Available online at http://www.ncbi.nlm.nih.gov/pubmed/20000517.
Parodi et al., 1982. Predictive 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. Available online at http://www.informaworld.com/smpp/
content~db=all~content=a915968516.
Ravishankara et al., 1993. Do Hydrofluorocarbons Destroy 
Stratospheric Ozone? A. R. Ravishankara, Andrew A. Turnipseed, Niels 
R. Jensen, Stephen Barone, Michael Mills, Carleton J. Howard, and 
Susan Solomon. Science, Vol. 263. no. 5143, pp. 71-75. January 4, 
1994. Available online at http://www.sciencemag.org/cgi/content/abstract/263/5143/71.
Rhasa and Zellner, 1987. Atmospheric Oxidation of Hydrocarbons. Free 
Radical Research 1987, Vol. 3, No. 1-5: Pages 199-209. Available 
online at http://informahealthcare.com/doi/abs/10.3109/10715768709069785.
Sciance, 2010. ``General Motors R-1234yf Implementation,'' 
Presentation by Fred Sciance, General Motors to EPA staff. October 
28, 2010. Docket number EPA-HQ-OAR-2008-0664-0138.

[[Page 17519]]

Spatz, 2008. Spatz, M and B. Minor 2008 ``HFO-1234yf: A Low GWP 
Refrigerant for MAC'', VDA Winter meeting. Available online at 
http://www2.dupont.com/Refrigerants/en_US/assets/downloads/SmartAutoAC/MAC_VDA08_HFO_1234yf.pdf.
SROC, 2005. Chapter 3 from Safeguarding the Ozone Layer and the 
Global Climate System: Special Report of the Intergovernmental Panel 
on Climate Change. Edited by Bert Metz, Lambert Kuijpers, Susan 
Solomon, Stephen O. Anderson, Ogunlade Davidson, Jose Pons, David de 
Jager, Tahl Kestin, Martin Manning and Leo Meyer. Cambridge 
University Press. 2005. Available online at http://www.cambridge.org/catalogue/catalogue.asp?isbn=9780521682060.
TNO, 2005. Sub-acute (2-week) Inhalation Toxicity Study with HFO-
1234yf in Rats. 2005. Docket number EPA-HQ-OAR-2008-0664-0020 and 
attachments -0020.1 through -0020.4.
TNO, 2007a. Sub-chronic (13-week) inhalation toxicity study with 
HFO-1234yf in rats. 2007. Docket number EPA-HQ-OAR-2008-0664-0022 
and attachments -0022.1 through -0022.5.
TNO, 2007b. Prenatal Developmental Inhalation Toxicity Study with 
HFO-1234yf in Rats. 2007. Docket number EPA-HQ-OAR-2008-0664-0023 
and attachments -0023.1 through -0023.9.
U.S. EPA, 1994. U.S. Environmental Protection Agency (U.S. EPA). 
1994. Methods for derivation of inhalation reference concentrations 
and application of inhalation dosimetry. EPA/600/8-90/066F. Office 
of Health and Environmental Assessment, Washington, DC. 1994. 
Available online at http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=71993.
U.S. EPA, 2000. Hazard Summary for Formaldehyde, CAS ID 50-
00-0. Revised 2000. Available online at http://www.epa.gov/ttn/atw/hlthef/formalde.html.
U.S. EPA, 2010a. E-mail from Yaidi Cancel, EPA. To William Hill and 
Ward Atkinson, SAE Interior Climate Control Committee re: Minimum 
recordkeeping on SAE J1739. August 16, 2010.
U.S. EPA, 2010b. E-mail from Margaret Sheppard, EPA to Christopher 
Seeton and Kasia Bober, Honeywell re: Summary of our conference call 
on service fittings for HFO-1234yf. November 8, 2010.
U.S. EPA, 2010c. Clarifying questions for Honeywell on Exposure 
Study. Docket number EPA-HQ-OPPT-2008-0918-0095.
Wallington et al., 2008. Emissions of CO2, CO, 
NOX, HC, PM, HFC-134a, N2O and CH4 
from the Global Light Duty Vehicle Fleet. Meteorologische 
Zeitschrift 17. 109-116. Available online at http://www.schweizerbart.de/resources/downloads/paper_free/56618.pdf.
Wallington et al., 2010. ``Estimated Photochemical Ozone Creation 
Potentials (POCPs) of CF3CF=CH2 (HFO-1234yf) 
and Related Hydrofluoroolefins (HFOs).'' T. Wallington, M. Andersen, 
O. Nielsen. Atmospheric Environment. Docket number EPA-HQ-OAR-2008-
0664-0084.2. Available online at http://www.sciencedirect.com or at 
doi:10.1016/j.atmosenv.2010.01.040.
Weissler, P., 2008. ``Consensus Building on Refrigerant Type.'' 
Automotive Engineering International. 9: 30-32. Docket number EPA-
HQ-OAR-2008-0664-0006.
WIL, 2006. Acute Cardiac Sensitization Study of [name redacted] and 
HFO-1234yf in Dogs. WIL Laboratories, 2006. Docket number EPA-HQ-
OAR-2008-0664-0019 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

0
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

0
2. Appendix B to Subpart G of Part 82 is amended as follows:
0
a. By adding one new entry to the end and by adding a note at the end 
of the first table.
0
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

[[Page 17520]]

                               Refrigerants--Acceptable Subject to Use Conditions
----------------------------------------------------------------------------------------------------------------
          Application                Substitute          Decision            Conditions             Comments
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
CFC-12 Automobile Motor Vehicle  HFO-1234yf as a    Acceptable         Manufacturers must      Additional
 Air Conditioning (New            substitute for     subject to use     adhere to all of the    training for
 equipment in passenger cars      CFC-12.            conditions.        safety requirements     service
 and light-duty trucks only).                                           listed in the Society   technicians
                                                                        of Automotive           recommended.
                                                                        Engineers (SAE)        Observe
                                                                        Standard J639           requirements of
                                                                        (adopted 2011),         Significant New
                                                                        including               Use Rule at 40
                                                                        requirements for:       CFR 721.10182.
                                                                        unique fittings,       HFO-1234yf is
                                                                        flammable refrigerant   also known as
                                                                        warning label, high-    2,3,3,3-
                                                                        pressure compressor     tetrafluoro-prop-
                                                                        cutoff switch and       1-ene (CAS No
                                                                        pressure relief         754-12-1).
                                                                        devices. For
                                                                        connections with
                                                                        refrigerant
                                                                        containers of 20 lbs
                                                                        or greater, use
                                                                        fittings consistent
                                                                        with SAE J2844.
                                                                       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 Air-Conditioning 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             R-405A................  Unacceptable..........  R-405A contains R-c318, a
 Conditioners (Retrofit and New                                                       PFC, which has an
 Equipment/NIKs).                                                                     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,  Unacceptable..........  The risks associated with
                                      other than R-152a or                            using flammable
                                      HFO-1234yf in new                               substitutes (except R-152a
                                      equipment.                                      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