*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 1 of 134 EO12866_SNAP HFO - 1234yf MVAC_RIN 2060 - AP11_Final_Rule_20101 214 .doc ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 82 [EPA - HQ - OAR- 2008 - 0664; FRL - xxxx - x] RIN 2060 - AP11 Protection of Stratospheric Ozone: New Substitute i n the Motor Vehicle Air Conditioning Sector under the Significant New Alternatives Policy (SNAP) Program AGENCY: Environmental Protection Agency (EPA). ACTION: Final Rule.

_______________________________________________________________________ SUMMARY: T he 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 dis approve substitutes that present overall risks to human health and the environment more significant than those presented b y other alternatives that are available or pote ntiall y av ailable. The substitute addressed in this final rule is for use in new passenger cars and light - dut y trucks in the motor vehicle air conditioning end - use within the refrigeration and air conditioning sector. EPA finds hydrofluoroolefin ( HFO ) - 12 34yf 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 DATES: This final rule is effective on [ insert date 60 days after publication ] .*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 2 of 134 ADDRESSES: EPA has established a docket for this action under Docket ID No. EPA HQ - OAR - 200 8 - 0664. All documents in the docket are listed on the 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 b y st atute. Certain other material, such as copy righted 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 www.regulations.gov or in hard cop y 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 holiday s. 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; Environme ntal 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 . T he 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) s ys tems in new passeng er*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 3 of 134 cars and light - dut y 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 appl y to me? II. What abbreviations and acron ym s 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 - 1234y f acceptable subject to use conditions? VI . What is the rel ationship between this SNAP rule and other EPA rules? A. S ignificant New Use Rule B. Rules under Sections 609 and 608 of the Clean Air Act VII. What is EPA ’s respon se to public comments on the proposal? A. Acceptability

decision B. Use conditions C. Environmental impacts D. Heal th and safet y impacts E. Retrofit usage F. Use b y “do - it - yourselfers” G. Servicing issues H. Cost, availability , and small business impacts*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 4 of 134 VIII . How does the SNAP program work? A. What are the statutory requirements and authority for the SNAP program? B. Wh at are EPA's regulation s 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 Safet y Risks H. Executive Order 13211: Actions that Significantly Affect Energy

Suppl y, Distribution, or Use I. National Technology

Transfer and Advancement Act J. Executive Order 12898: Federal Actions to Address Environmental Justice in Minority Populations and L ow - Income Populations K. Congressional Review Act*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 5 of 134 X. References I. Does this Action Apply to Me? This final rule regulates the use of the chemical HFO - 1234yf (2,3,3,3 - te trafluoroprop 1 - ene , Chemical Abstracts Service Registry Number (CAS Reg. No. 754 - 12 - 1 ) as a refrigerant in new motor vehicle air conditioning (MVAC) s ys tems in new passenger cars and light - dut y trucks . Businesses in th is end - use that might want to us e HFO - 1234yf in new MVAC s ys tems in the future include:

 automob ile manufacturers

 manufacturers of motor vehicle air conditioners Regulated entities may

include: Table 1

– Potentially Regulated Entities, by North American Industrial Classification System ( NAICS) Code Category NAI CS code Description of regulated entities Industry 336111 Automobile M anufacturing Industry 336391 Motor Vehicle Air - Conditioning Manufacturing This table is not intended to be exhaustive, but rather a guide regarding entities likely to be regulated b y this action. If you have an y questions about whether this action applies to a particular entity , consult the person listed in the preceding section, “FOR FURTHER IN FORMAT ION CONTACT.” II. What abbreviations and acronyms are used in this action? 100 - yr - one - hundred ye ar time horizon AEGL - Acute Exposure Guideline Level*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 6 of 134 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 fuer Materialforschung und

–pruefung (the German Federal Institute for Materials Research and Testing) CAA - Clean Air Act CAS Reg. No. - Chemical Abstracts Service Registry Number CBI - C onfidential B usiness Information CFC- chlorofluorocarbon CFC - 12 - the ozone - depleting chemical dichlorodifluoromethane, CAS Reg. No. 75 - 71 - 8 CFD - C omputational F luid D yn amics CFR - Code of Federal Regulations cm/s - centimeters per second CO2 - carbon dioxide, CAS Reg. No. 124 - 38 - 9 CRP - Cooperative Research Pro gram DIN - D eutsches Institut fuer 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 - Failur e Mode and Effect Anal ys is FR - Federal Register*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 7 of 134 GW P - Global W arming P otential HF - H ydrogen F luoride, CAS Reg. No. 7664 - 39 - 3 HI - H azard Index HFC - hydrofluorocarbon HFC - 134a - the chemical 1,1,1,2 - tetrafluoroethane, CAS Reg. No. 811 - 97 - 2 HFC - 152 a - the chemical 1,1 - d ifluoroethane, 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 - Li fecycle Analy sis LCCP - Li fecycle C limate P erformance LFL - L ower F lammability L imit LOAEL - L owest O bserved A dverse E ffect L evel mg/L - milligram per liter MIR - M aximum Incremental R eactivity mJ - millijoule mm - millimeter MOE- M argin of E xposure MPa - mega

pascal MRL - Minimal Risk Level MVAC- Motor Vehicle Air Conditioning*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 8 of 134 NAICS -North American Industrial Classification Sy stem ng/L - nanograms per liter NH TSA - the U.S. National Highway Traffic Safety Administration N OAEL -N o O bserved A dverse E ffect L evel NOEC-N o O bserved E ffect C oncentration NPRM -Notice of Proposed Rulemaking NTTAA -National Technology Transfer and Advancement Act ODP - O zone D epletion P otential ODS - O zone - D epleting S ubstance OEM - O riginal E quipment M anufacturer OMB - Office of Management and Budget OSHA - the United States Occupational Safety and Health Administration PAG - P olyalkyl ene G lycol PMN - Pre - Manufacture Notice POCP - Photochemical O zone C reation P otential POD - Point of Departure p pm - parts per million ppt- parts per trillion psig- pounds p er square inch guage 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 CO 2*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 9 of 134 RCRA - the Resource Conservation and Recovery Act RFA - Regulatory

Flexibility

Act SAE- SAE International, formerl y the Societ y of Automotive Engineers SBA - the United States Small Business Administration SIP- State Implementation P lan SNAP - Significant New Alternatives Policy SNUN - Significant N ew Use Notice SNUR - Significant New Use Rule SO2 - sulfur dioxide, CAS Reg. No. 7446 - 09 - 5 TEW I - Total Equivalent Warming Impact TFA - Trifluoroacetic acid, CF 3 COOH, also known as trifluoroethanoic acid, CAS Reg. No. 76 - 05 - 1 TSCA - the Toxic Substances Control Act TW A - T ime - W eighted Average UF - Uncertaint y Factor UMRA - Unfunded Mandates Re form Act VDA - Verband der Automobilindustrie (German Association for the Automobile Industry) VOC- V olatile O rganic C ompound v/v - volume to volume WEEL - W orkplace E nvironmental E xposure L imit*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 10 of 134 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 sy stems 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 sy stems. In addition, it does not apply to the use of HFO - 1234yf in the air conditioning or refrigeration s ys tems of heavy - dut y trucks, ref rigerated 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 sy stems. This final rule is adding HFO - 1234yf to the list of acceptable substitutes, subject to use conditions, in new MVAC sy stems. Automobile manufacturers have the option of using an y 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 sy stem for passenger cars and light - dut y trucks : 1. The high - pressure side of the MVAC sy stem shall have a pressure relief device located in the high pressure side of the compressor or immediatel y adjac ent to the compressor discharge fitting . The device shall releas e refrigerant onl y outside of the passenger , trunk, and storage compartments and MVAC air distribution sy stem . The se pr essure relief devices shall be design ed to minimize impingement of the refrigerant and oil on hot surfaces.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 11 of 134 2. The MVAC sy stem high - pressure side relie f device identified above in 1 . shall be self - sealing. In no case shall the maximum release (blow - off) pressure be greater than the maximum refrigerant working pressure. 3. To preve nt unnecessary discharge of refrigerant during operation, the s ys tem shall have a means to limit the compressor operation by cutting off transmission of power to the compressor before any component failure occurs and before activation of any pressure relie f device (i.e., compressor cutoff switch). 4. In no case shall an y high - pressure side refrigerant pressure relief valves (or burst disks) have an activation pressure greater than the maximum working pressure of 4.14 MPa. Gauge (600 psig). 5. The maximum pressure on the low - pressure side of the MVAC sy stem shall not e xceed the saturation pressure of HFO - 1234yf at 56 o C. 6. HFO - 1234yf refrig erant sy stems connections shall either be :

 L ocated outside the passenger compartment and outside the passenger cabin airflow path . or

 D esigned to prevent leakage if the connections are located inside

the passenger cabin or in the passenger cabin airf low path . For safet y reasons, i ndividuals performing servicing shall follow the service and repair leakage recommendations (e.g., fro m manufacturer and in service shop manual), including an y s ervice*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 12 of 134 procedures established to prevent refrigerant from entering the cabin or airflow path . 7. High - side and low - side fittings shall be fitted with protective or sealing caps. 8. All M VAC sy stem s ervic e fittings shall be located for ease of attachment of service hoses and shall be designed to minimize direct impingement of refrigerant on the service technician. Piping shall be of robust design to avoid damage or permanent deformation while connecting o r disconnecting the service hose coupling(s) from factory charging and service equipment. 9. HFO - 1234yf must be used with the following service fittings: o For the low - side service port, use quick - connect fittings with an out side diameter of 14 + 0.2 mm (0.551 + 0.00787 inches) . o For the high - side service port, use quick - connect fittings with an out side diameter of 17 + 0.2 mm (0.669 + 0 .00787 inches) . o For connections with containers of 20 lbs or greater, use quick connect fittings with an out side diameter of 1 4 + 0.2 mm (0.551 + 0.00787 inches) . o All fittings must be different from those for any other refrigerant. 10. A plainly

legible and durable refrigerant label shall be mounted in a clearly visible location under hood that does not require the removal of any parts or covers to be read . The label shall : identif y the refrigerant ; state the amount of refrigerant charge in grams (or kilograms, to three decimal places); and identify the lubricant ty

pe (polyalkylene gl ycol [PAG] or polyolester [POE]) . The label eithe r shall include the chemical safet y sy mbol for “ flammable ” or*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 13 of 134 shall state in text that the refrigerant is flammable in letters at least 3 mm in height that are red in color. The label shall contain the name or logo of the original equipment vehicle manufa cturer or the refrigeration s ys tem manufacturer responsible for design compliance with this rule and with SAE standards . The label shall have a minimum size of 60 mm by 30 mm. It shall have text in bold - ty

pe letters at least 3 mm in height for identifyin g refrigerant, lubricant ty

pe and refrigerant amount. If the label contains text only and no sy mbols, th e label shall also state the following : “ CAUTION SYSTEM CONTAINS REFRIGERANT R - 1234yf UNDER HIGH PRESSURE - TO BE SERVICED ONLY BY QUALIFIED PERSONNEL ” 11. Manufacturers must conduct Failure Mode and Effect Anal ys is (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. Once the standard SAE J639 becomes final with provisi ons for HFO - 1234yf, EPA will consider replacing use conditions 1 through 10 with a use condition requiring the safet y provisions of SAE J639. IV. What are the final use conditions and why did EPA finalize these conditions ? Summary of the use conditions This rule finalize s ten use conditions that were included in the draft SAE standard J639 , which was available during the comment period on the proposed rule . T he SAE standard has not yet been finalized. Thus, since EPA is unable to refer to the final SAE standard in the final rule, EPA instead is including in the use conditions the safet y*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 14 of 134 requirements provided in the draft SAE standard 1 referred to in the proposed rule and in cluded in the docket (EPA - HQ - OAR - 2008 - 0664 - 0012) . The eleventh use condition requir es the manufacturer of MVAC sy stems and vehicle s (i.e., the original equipment manufacturer [OEM]) to conduct and keep records of a risk assessment and failure Fault Mode and Effects Analy sis ( FMEA ) for at least three ye ars from the date of creation . Ther e is an existing industry standard, SAE J17 3 9, 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 ( US 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 safet y requirements in the standard SAE J639, “ Safet y Standards for Motor Vehicle Refrigerant Vapor Compression Sy stems ” and required use of unique servicing fittings from that standard . Another use condition required automobile manufacturers to perform Fault Mode and Effect Analy sis (FMEA) and to keep records of the FMEA. T he remaining three proposed use conditions specifically address ed risks of flammability

of HFO - 1234yf and indirectl y address ed risks of generating hydrogen fluoride (HF) from combustion of HFO - 1234yf. For the first of those proposed use conditi on s , which addressed the passenger compartment, the concentration of HFO 1234yf was not to exceed the lower flammability limit ( LF L ) in the free space for more than 15 seconds. For the second proposed use condition, which addressed the engine

1 The safety requirements cited here are from sections 5, 7, 9, 10, and 12 of the draft standard SAE J 639 (Sy stem and Component Requirements; Service Port Fittings; Service Fitting Cap s; Requirements for MAC Sy stem Labeling; and Refrigerant Line Routing and Refrigerant Connections).*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 15 of 134 compartment, the concentration of HFO - 1234yf was not to exceed the LFL for an y 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 hy brid or electric vehicle electric power sources. EPA based o ur determination of the appropriate use conditi ons 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 opportunit ies 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 (hereaf ter called the SAE CRP) issued a new report on December 17, 2009 assessing risks of HFO - 1234yf and carbon dioxide ( CO 2 ) as refrigerants for MVAC. This report found that the risks of HFO - 1234yf were low overall, and somewhat less than risks for another pot ential alt er n ative refrigerant (CO 2 , also know as R - 744 ). The December 2009 CRP report found that the great est 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 s ys tem.) The SAE CRP estimate s 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. Th e s e*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 16 of 134 correspond roughly to one occurrence in the entire US fleet of passenger vehicles over 2 ye ars for HF risks and on e occurrence in the US vehicle fleet every 100 years for flammability

risks. 2 For comparison, th e 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 deploy

ment of an airbag during a vehicle collision (E PA - HQ - OAR - 2008 - 0664 - 0056.2). Even these estimates may be conservative because they assume that refrigerant could be released in a collision severe enough to rupture the evaporator (under the windshield) while the windshield and windows would remain intact and would prevent ventilation into the passenger cabin in case of a collision (EPA - HQ - OAR - 2006 - 0664 - 0056.2). Second, we received a number of public comments regarding the proposed use conditions . Some commenters claimed that the second use condition con cerning concentrations in the engine compartment was infeasible because in the event of a leak, there would alway s be some small volume that would have a concentration over the LFL ; these commenters further stated that exceeding the LFL would not necessari ly 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, gi ven the results of the SAE CRP risk assessment (December 17, 2009) . These commenters st at ed that the use conditions limiting refrigerant concentrations were not necessary . These commenters also suggested a number of alternative way s of phrasing the use c onditions in order to address risks from HF as well as flammability . Most of 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*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 17 of 134 these comments suggested relying on the perform ance of a risk assessment and Fault Mode Effect Anal ys is (FMEA) consistent with SAE J1739 to determine appropriate protective strat egies . 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 toxi city

of HFO - 1234yf; and (3) risks from flammability of HFO - 1234yf because the LFL becomes lower than 6.2% at temperatures higher than 21oC (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 de cid ed 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 leve ls of risk i dentified for HFO - 1234yf from flammability

and from ignition of HF (EPA - HQ - OAR - 2008 - 0664 - 0056.2) . The highest risk identified for HFO - 1234y f is potential consumer exposure to HF from decomposition and ignition, which is of the same order of ma gnitude 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 previousl y found HFC 134a acceptable for use in new and retrofit MVAC sy stems (5 9 FR 13044 ; March 18, 1994; and 60 FR 31092, June 13, 1995) , without use conditions address ing risks of HF .

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 N um ber (CAS Reg. No.) is 811 - 97 - 2 .*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 18 of 134 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 s ys tem , 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 alternatives in this end - use that EPA has already listed or proposed as acceptable (e.g., HFC - 152a 4 , HFC - 13 4a, and CO 2 ) (EPA - HQ - OAR - 2008 - 0664 - 0086.1) . We have concluded that the use conditions we are including in the final rule address the risks from both HF and flammability . U se conditions in the final rule that were taken from the draft industry standard SAE J639 provide for a pressure relief device designed to minimize direct impingement of the refrigerant and oil on hot surfaces and for d esign 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 sy stem will not reach an unsafe level that might cause an uncontrolled, explosive leak of refrigerant, such as if the air conditioning sy stem is overch arged. 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 passe nger cabin ensures that if there is a leak, the refrigerant is unlikely to enter the passenger cabin . Keeping refrigerant out of the passenger cabin minimiz es the

4 HFC - 1 52 a is also known as 1,1 - di fluoroethane or, when used as a refrigerant, R - 1 52 a. The CAS Reg. No. is 75 - 37 - 6.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 19 of 134 possibility

that there would sufficient levels of refrigerant to reach flammable concentrati ons or that HF would be formed and transported where passengers might be exposed. The last proposed use condition , re quiring manufacturers to conduct and keep records of FMEA according to the standard SAE J1739 remains unchanged. The proposed use condi tion regarding conducting and keeping records of a Fault Mode and Effects Analy sis 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 specif ic language adopted from the 2010 draft version of the standard. This incorporates language from the most recent version of the standard , with new provisions designed specificall y to address use of HFO - 1234yf. In terms of substance, the final use conditi ons are essentiall y the same as a number of provisions that were under consideration by SAE and were made in the docket at the time of proposal (see EPA - HQ - OAR - 2008 - 0664 - 0012 and the proposed use condition) . V. Why is EPA finding HFO - 1234yf acceptable subjec t 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 significantl y greater overall impact on human health and the environment than oth er available or potentially

available substitutes for CFC - 12 in MVAC sy stems . Examples of other substitutes that EPA has already found acceptable subject to use condition s for use in MVAC include HFC - 134a and HFC - 152a . HFC - 134a is the alternative most wi dely used in MVAC sy stems today . EPA has also proposed to find CO 2 (R - 744) acceptable subject to use conditions in MVAC ( September 14, 2006; 71 FR 55140 ) .*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 20 of 134 All alternatives listed as acceptable for use in MVAC sy stems in passenger cars and light - dut y truck s are required to have unique fittings under use conditions issued previously under the SNAP Program at 40 CFR part 82, appendix D to subpart G ( 61 FR 54040, October 16, 1996). Thus, all substitutes for use in MVAC sy stems in passenger cars and light - dut y 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 sy stems are quick - connect fittings with an ex ter

nal diameter large enough that they will not connect with cars or refrigerant containers for HFC - 134a or an y other refrigerant , as described in the ni nth use condition above in section II. The original submitter of HFO - 1234yf to the SNAP program has provi ded EPA with a copy of and a diagram for these unique fittings. As described above, the fittings will be quick - connect fittings, different than those for an y other refrigerant. The low - side service port and connections with containers of 20 lbs or greate r will have an out side diameter of 14 mm (0.551 inches) and the high - side service port will have an out side diameter of 17 mm (0.669 inches) , both accurate to within 2 mm . The submitter has not provided, and the draft SAE J639 standard does 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 s ys tems. In addition to the use conditions regarding unique fittings , which appl y under appendix D to subpart G of 40 CFR part 82 , EPA is requiring use conditions for the safe design of new MVAC s ystems using HFO - 1234yf , consistent with standards of the

5 The draft 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 - s ide service port in draft SAE J639 and is also specified in SAE J 2844, “R - 1234y f New Refrigerant Purity and Container Requirements Used in Mobile Air - Conditioning Systems.” (US EPA, 2010b)*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 21 of 134 automotive industry (e.g., SAE J1739 , draft standard SAE J639 ) . Th e s e use conditions are intended to ensure that new cars and light - duty trucks that have MVAC sy stems that use HFO - 1234yf are specificall y 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. T he industry

standard SAE J1739 gives guide lines 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 - 1234y f were for approximately $40 - 60/pound (Weissler, 2008). The first automobile manufacturer to announce its commitm ent 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 sub mitter, 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 Uni on directive to use only refrigerants with GWP less than 150 in new automobile designs starting in 2011. Environmental impacts EPA finds that HFO - 1234y f does not pose significantly greater risk to the environment than the other substitutes that are curre ntly or potentially

available. In at*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 22 of 134 least in one aspect, HFO - 1234yf is significantl y better for the environment than other alternatives currentl y found acceptable subject to use conditions. HFO - 1234yf has a hundred - ye ar time horizon (100 - yr) global warm ing potential (GWP) of 4 (Nielsen et al., 200 7 ; Papadimitriou et al. , 2007 ) , compared to a GWP of 124 for HFC - 152a, and a GWP of 1430 for HFC - 134a (IPCC, 2007) . CO 2 , an other substitute currentl y under review in this end - use , has a GWP of 1 , which is lower , but comparable to the GWP of HFO 1234yf . 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 - 416 A, and R - 420A. Further, HFO - 1234yf has n o ozone depletion potential (EPA - HQ - OAR - 2008 - 0664 - 0013) , comparable to CO 2 , HFC - 152a, and HFC - 1 34a, and has less risk of ozone depletion than all refrigerant blends containing HCFCs that EPA previously found acceptable subject to use conditions for MVAC sy stems . 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 anal ys is that assumed widesp read 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 (I CF, 2009; I CF, 2010a,b,c,e). Thus, we believe that actual environme ntal impacts are likel y 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*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 23 of 134 (VOC). Available information indicates that HFO - 1234yf has greater photochemical reactivit y 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 exempt ed VOC s with negligible photochemical reactivity from regulation ( 40 CFR 51.100(s) ) . The manufacturer of HFO - 1234yf has submitted a petition to EPA request ing that the chemical be exempted from regulation as a VOC, based on a claim that it has m aximum inc remental reactivity comparable to that of ethane (EPA - HQ - OAR - 2008 - 0664 - 0 116.1 ). Separate from this action, EPA is reviewing that request and plans to issue a proposed rule shortly

to address it. Regardless of whether EPA determines to exempt HFO - 1234yf from regulation as a VOC for state planning purposes, o ther anal ys es 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 anal ys is that finds a worst - case increase in the Los Angeles region of 0.080 pp b, or a contribution of only 0.1% of the 1997 8 - hour standard for ground - level ozone of 0.08 ppm (I CF, 2010 b ). Our initial anal ysis at the proposal stage had estimated a maximum increase in ozone of 1.4 to 4.0% of the standard in the same region (I CF, 200 9). The major difference between the 2009 and the 2010 versions of th is analy sis involv ed modeling of atmospheric chemistry . The 2010 study was based on the kinetics and decomposition*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 24 of 134 products predicted for HFO - 1234yf, rather than using the oxidation of sulfur dioxide ( SO 2 ) as a prox y for decomposition of HFO - 1234yf as was done in the 2009 study . The 2010 anal ys is used updated baseline emission estimates that were 1. 5 % higher to 5.8% lower than those in the 2009 anal ys is , 6 depending on the ye ar anal yz ed (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 anal ys is (ICF, 2009 ; I CF, 2010c ). Another potential environmental impact of HFO - 1234yf is its atmospheric decomposition to trifluoroacetic acid (TFA , CF 3 COOH ). TFA is a strong acid that may accumulate on soil, on plants, and in aquatic ecosy stems over time and that may have the potential to adversel y impact plants, animals, and ecos ys tems. Other fluorinated compounds also decompose into TFA, including HFC - 134a. However, the amount of TFA produced from HFO - 1234yf in MVAC is esti mated to be at least double that of current natural and artificial sources of TFA in rainfall (Luecken et al., 2009) . An initial anal ys is performed for EPA at the proposal stage found that , with highl y conservative emission estimates, TFA concentrations i n 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

6 These changes in estimates reflect ongoing updates to EPA’s Vintaging Model, a model that considers industry trends in different end - use s 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 - 1234y f of approximately 50 g/yr per vehic le, 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) .*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 25 of 134 1 mg/L for the most sensitive plant species (ICF, 2009 ). This anal ys is concluded,

“ Projected levels of TFA in rainwater should not result in a significant risk of ecotoxicity .” A more recent anal ys i s by Luecken et al (2009) that became available during the initial public comment period rea ched the conclusion that emissions of HFO 1234yf from MVAC could produce TFA concentrations in rainwater of 1/800 th to 1/80 th the no - observed adverse effect level (NOAEL) for the most sensitive algae species expected (Luecken et al., 2009). The conclusion s in the Luecken study are supported by additional anal ys es that have become available since we issued the proposed rule. A study from the National Institute of Advanced Industrial Science and Technology (AI ST) 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 roughl y 1/80 th the NOAEL for the most sensitive algae species, even with assumptions of high emissions levels (i.e., assuming that all t ypes of refrigeration and AC equipment currently

using HFCs or HCFCs , not just MVAC sy s tems, would use HFO 1234yf ) . Kajihara et al. (2010) evaluated sc enarios specific to Japan, with emissions of approximately

15,172 ton/y

r in 2050, compared to a maximum of 64,324 metric tons/yr in 2050 in I CF, 2009 or a maximum of 24,715 metric tons/y r in 2017 in Luecken et al (2009). All three studies noted the potent ial for accumulation in closed aquatic sy stems. 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 L os Angeles area , could e xceed the no observed adverse effect concentration for the most sensitive plant species, but annual values would never exceed*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 26 of 134 that value. Further, TFA concentrations would never approach levels of concern for aquatic animals (ICF, 2009 ) . In a more recent analy sis, ICF ( 2010 a, b, c , e ) perform ed modeling for EPA using the kinetics and decomposition products predicted specificall y for HFO - 1234yf and consider ed revised emission estimates that were slightly l ower than in a 2009 anal ys is (ICF, 2009). The revi sed anal ysis found a maximum projected concentration of TFA in rainwater of approximately 1,700 ng/L, roughl y one - thousandth of the estimate from our 2009 anal ys is (ICF, 2010b) . This maximum concentration is roughl y 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 1/600 th of the NOAEL for the most sensitive algae species

— thus, it is not a level of concern . We find th ese additiona l analy ses 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 propos al . Human health and safety impacts Occupational risks could occur during the manufacture of the refrigerant , initial installation of the refrigerant into the MVAC sy stem at the car assembl y plant , servicing of the MVAC sy stem , or final disposition of the MVAC sy stem ( i.e., recycling or disposal) . Cons umer 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 s ys tem 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.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 27 of 134 To evaluate these potential human health and safety impacts, w e con sidered EPA ’ s own risk assess ments (EPA - HQ - OAR - 2008 - 0664 - 0036 and - 0038 ) , as well as detailed risk assessment s with fault - tree anal ys is from the SAE CRP for HFO - 1234yf and CO 2 (EPA - HQ - OAR - 2008 - 0664 - 0008 and - 00 56 .2 ) , and scientific data provided in public comments on the topics of health and safety risks . 8 Health and safet y risks that we evaluat ed 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 flamm ability

of HFO - 1234yf. Occupational risks For long - term occupational exposure to HFO - 1234yf , EPA compared worker exposures to a workplace exposure limit of 250 ppm 9 over an 8 - hour time - weighted average. For short - term occupational exposure to HFO - 1234yf , we compared worker exposure to an acute exposure limi t of 9 8 ,211 ppm , divided by a margin of exposure of 30, for a value of 3270 ppm over 30 minutes . 10 , 11

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 th e 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 result s 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 condition s. 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 workpl ace 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. Th is 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 N OAEL of 5 1 , 69 0 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*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 28 of 134 Section 609 of the Clean Air Act requires technicians servicing MVAC s ys tems 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. Th erefore , we expect that professional technicians have the proper equipment and know ledge to minimize their risks due to exposure to refrigerant from an MVAC sy stem. Thus, w e 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., servici ng practices, certification requirements for recovery and recycling equipment intended for use with MVACs using HFO - 1234yf , an y potential changes to the rules for training and testing technicians, and recordkeeping requirements for service facilities and f or refrigerant retailers ) . If workers service MVAC sy stems using certified refrigerant recovery equipment after receiving training and testing , exposure levels to HFO - 1234yf are e stimate d to be on the order of 4 to 8.5 ppm on an 8 - hour time - weighted avera ge (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;

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 wa s calculated as follows: 5 1 , 69 0 ppm (animal exposure) x 1.9 (ratio of estimated human exposure/animal exposure) = 98,211 ppm This value was th en 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 11 5,000 ppm over 30 minutes to evaluate risks for these same time periods . These are b ased on the 8 - hr Workplace Environmental Exposure Limit ( WEEL ) for HFO - 1234y f 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 gr ey 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.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 29 of 134 EPA - HQ - OAR - 2008 - 0664 - 00 3 8 ) . We al so anal yzed 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, th e manufacture, use , and disposal or recycling of HFO - 1234yf are not expected to present a toxicity risk to workers. We did not analy

ze the risk of generation of HF in the workplace. In its December 17, 200 9 Risk Asse s sment for Alternative Refrigerants HFO - 1234yf and R 744 (CO 2 ) , 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 - b ased limit” ( EPA HQ - OAR - 2008 - 0664 - 0056 .2 ) . Since there is a similar potential to form HF from other MVAC refrigerants that have been use d for years , such as CFC - 12 or HFC - 134a, it is reasonable to assume that service technicians, recyclers, and disposers will handle HFO 1234yf similarl y 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 discuss ed 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 - 1234y f, ignition of the refrige rant will not contribute substantially

to a pre - existing fire” (EPA - HQ - OAR - 2008 - 0664 - 0056.2) . EPA considers this reasona

ble, 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 4 2 cm/s ( Ceviz and Yuksel, 2005 ) . Concerning first responder exposure*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 30 of 134 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 . O ther MVAC refrigerants containing fluorine such as CFC - 12, which was historicall y used, and HFC - 13 4 a , which is the predominant refrigerant currentl y 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 p repare d 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. Mod eling 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). T he 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 sy stem 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 onl y i n the most conservative simulation, with the largest refrigerant leak and with all air being recirculated within the passenger cabin (EPA - HQ - OAR - 2008 - 0664 - 00 10). Updated CFD modeling performed for the December, 2010 SAE CRP risk assessment found that*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 31 of 134 concentrations of HFO - 1234yf sometimes exceeded the LFL, but onl y w ithin 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 - 2 6 cases per working hour . We note that HFO - 1234yf is less flammable and results i n 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 sy stems subject to use conditions. Thus, EPA finds that the risks of flammability in the workplace from HFO - 1234yf are similar to or low er than the risk posed by currentl y available substitute s when the use conditions are met . Consumer exposure EPA’s review of consumer risks from toxicity of HFO - 1234yf indicated that p otential consumer (passenger) exposure from a refrigerant leak into the passenger compartment of a vehicle is not expected to pr esent an unreasonable risk (EPA - HQ OAR - 2008 - 0664 - 0036, EPA - HQ - OAR - 2008 - 0664 - 0038 ) . However, consumer exposure from filling, servicing, or maintaining MVAC s ys tems may cause exposures at high enough concentrations to warrant concern. Specifically , this ri sk may be due to a lack of professional training and due to refrigerant handling or containment with out the use of refrigerant recovery equipment certified in accordance with the regulations promulgated under CAA Section 609 and codified at 40 CFR p art 82 , subpart B . Consumer filling, servicing, or maintaining of MVAC sy stems may cause exposures at high enough concentrations to warrant concern ( EPA - HQ - OAR - 2008 - 0664 - 0036 ). However, this rule*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 32 of 134 does not specificall y allow for use of HFO - 1234yf in consumer fil ling, servicing, or maintenance of MVAC sy stems. 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 provid e 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 sy stem 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 maint enance of MVAC s ys tems with HFO - 1234yf. EPA ha s is s u ed a significant new use rule (SNUR) under the authorit y of TSCA . ( Octo ber 2 7 , 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. M anufacturers, importers and processors of substanc es subject to a SNUR must notify

EPA at least 90 day s before beginning an y designated significant new use through a significant new use notice (SNUN) . EPA has 90 day s from the date of submission of a SNUN to decide whether the new use "may present an unre asonable 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 i dentified in the SNUR for*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 33 of 134 HFO - 1234yf are: (1) use other than as a refrigerant in motor vehicle air conditioning sy stems in new passenger cars and vehicles ; (2) commercial use other than in new passenger cars and vehicles in which the charging of motor veh icle air conditioning sy stems with HFO - 1234yf was done by the motor vehicle OEM; and (3) distribution in commerce of products intended for use b y a consumer for the purposes of servicing, maintenance and disposal involving HFO - 1234yf . Under existing regul ations in a ppendix D to subpart G of 40 CFR part 82, “A refrigerant may

onl y be used with the fittings and can taps specificall y 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 sy stem and for large cylinders for professional use (ty picall y 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 cont ainers for MVAC , we would first need to conclude through either review under

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 technician s might use (e.g., 50 lb, 20 lb, 10 lb).*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 34 of 134 TSCA or under the SNAP program that use of these smaller canisters would not pose an unreasonable risk to consumers. In our review of consumer risks from HFO - 1234yf , we consider ed information concerning consumer exposure to HF from thermal decomposition or combustion of HFO - 1234yf. EPA’s analy sis 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, w e had available and did consider the SAE CRP’s 2008 evaluation of scenarios that might cause consumer or occupationa l 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 b y combus tion of other automotive c omponents and thus decomposition of the refrigerant may increase the risk for fire fighters and would not introduce an entirely new ty pe of hazard. It is also anticipated that only

a small portion of the refrigerant charge will b e converted to these decomposition products. In U.S. EPA's assessment of risk of R - 152a and CO 2 (R - 744), the agency

cited a study

by Southwestern Laboratories which indicated that a 100% R - 134a atmosphere onl y produced an HF concentration of 10 ppm when p assed through a tube heated to 1,000 oF (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 COF 2 or HF produced in fires invol ving 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 likel y to lead to HF formation (EPA - HQ - OAR - 2008 - 0664 - 0056.2) . One test on H F 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*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 35 of 134 concentration s from thermal decomposition of HFO - 1234yf reach ed 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 ( flas h ignition, temperature of 70 0 ° 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 L imit (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 an y permanent effects. HF l evels that could result in similar effec ts 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 - 00 56.2 ). This level of risk is similar to the current level of risk o f HF generated from HFC - 134a ( EPA - HQ - OAR - 2008 - 0664 - 00 86.1) . To date, EPA is unaware of any reports of consumers affected by HF generated by

HFC 134a , which has been used in automobile MVAC sy stems across the industry since 199 3 . Thus, we do not expect th ere will be a significant risk of HF exposure to consumers from HFO - 1234yf.

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 US and typical driving times of 500 hours per year per vehicle, a risk of 4.6 x 10 - 12 per operatin g hour equates roughly to one event every 2 years for all drivers in the entire U.S .*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 36 of 134 Depending on the charge size of an HFO - 1234yf MVAC sy stem, 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 concentr ations of the refrigerant into the passenger compartment , provided that the windows and windshield remain intact . As stat ed in the SAE CRP, ignit ion of the refrigerant once in the passenger cabin is unlikely (probability on the order of 10 - 14 occurrences per operating hour) because the onl y 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 - 00 56 .2 ) . If a passenger were in a collision , or in an emergency situati on, it is unlikely

that they would choose to operate a butane lighter in the passenger cabin . Additionally , i t is unlikely ignition w ould occur from a flame from another part of the vehicle because autom o biles are constructed to seal off the passenger compartment with a firewall . If a collision breach ed 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 lower flammab ility 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 likel y 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 m inimum ignition energy*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 37 of 134 than HFO - 1234yf (EPA - HQ - OAR - 2008 - 0664 - 00 08, - 0013. 4 , - 0056.2 ) . Overall conclusion EPA finds that the use of HFO - 1234yf in new passenger vehicle and light - duty truck MVAC sy stems , subject to the use conditions being adopted in the fin al 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 CO 2 , which has been proposed for approval in this end - use . VI 

## . What is the relationship betwe en this SNAP rule and other EPA rules? A. Significant New Use Rule Under the Toxics Substances Control Act, EPA has issu ed a Significant New Use Rule (75 FR 65987 ; Octo ber 2 7 , 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 day s before such activity may occur. E PA has 90 day s from the date of subm ission 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 sy stems in new passenger cars and vehicles ; commercia l use other than in new passenger cars or vehicles and in which the charging of motor vehicle air conditioning sy stems with HFO - 1234yf was done by the*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 38 of 134 motor vehicle OEM; and distribution in commerce of products intended for use by a consumer for the purpos e of servicing, maintenance and disposal involving HFO - 1234yf . The health concerns expressed in the final SNUR are based primaril y on potential inhalation exposure s to consumers during “do - it - yourself” servicing, as well as a number of other relevant fact ors. B. Rules under Sect ions 609 and 608 of the C lean A ir A ct Section 609 of the CAA establishes standards and requirements regarding servicing of MVAC s ys tems. These requirements include training and certification of any person that services MVAC sy ste ms 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 40 CFR part 82 subpart B. The stat utory and regulatory

provisions regarding MVAC servicing appl y to an y 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 s ys tems. Thus, the r equirements in this rule apply primaril y 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. VI I . What is EPA ’s respon se to public comments on the proposal? This section of the preamble summarizes the major comments received on the October 19, 2009 proposed rule. Additional comments are addressed in a response to comments document in docket EPA - HQ - OAR - 200 8 - 0664.

15 Service for consideration means receiving something of worth or value to perform service, whether in mo ney , credit, goods, or services .*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 39 of 134 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 - 1234y f 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 - 1234y f’s risks were similar to or less than those of other available alternatives, such as HFC - 134a, HFC - 152a, and CO 2 . A commenter referenced the work of the SAE CRP, which concluded that HFO - 1234yf can be used safel y through established industry

pr actices for ve hicle 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 th an those of other available alternatives, such as HFC 134a, CO 2 , 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 safel y in MVAC s ys tems in new passenger vehicles and light - dut y trucks. T he 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 availabl e substitutes, such as HFC - 134a, HFC - 152a, or CO 2 . EPA did not compare the risks to those posed by

hydrocarbons since we have not yet received adequate*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 40 of 134 information for hydrocarbons that would allow us to make such a comparison for use in MVAC . 16 Comment: Some commenters suggested that EPA should consider other substitutes for CFC - 12 in MVAC, such as CO 2 or hydrocarbons. An organization representing the automotive industry stated that the risks from using CO 2 in MVAC sy stems 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: Th is rule onl y 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 CO 2 acceptable subject to use conditions as a substitute for CFC - 12 in MVAC sy stems for new motor vehicles (September 16, 2006; 71 FR 55140). We anticipate taking final action on that proposal shortl y . We currentl y have inadequate information on hydrocarbons to consider adding them to the list of substitutes for MVAC . We will review additional substitutes if they are submitted with complete and adequate data to allow an evaluation of whether such su bstitutes may

be used safel y 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 c ommenters stated that the proposed use conditions limiting concentrations of HFO - 1234yf below the lower flammability limit are overly

stringent or 16 EPA previously revie wed 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 C FR part 82.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 41 of 134 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 commenter s expressed concern that the proposed use conditions limiting concentrations of HFO - 1234yf would preclude the use of HFO - 1234yf b y an y 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 re mov ed the first three proposed use conditions, which requ ired 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 th is decision is limited to use in new motor vehicles and light - duty trucks . Further, the propose d 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 fuer Materialforschun g und

–pruefung (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*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 42 of 134 below the 6.2% LFL to ensure s afety . Other commenters agreed with these concerns. Yet o ther c ommenters look ed at the same test data and stated that the testing was not relevant to real - world situation s 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 c ommenter stated that HFO - 1234yf reduces the flammability of ethane compared to ethane alone, and that HFO - 1234yf reduces flammability of ethane more than CO 2 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 t ypically liquid and there is no evidence that an y vapors that might fo rm would include significant amounts of ethane . T hese fluids ty

picall y contain larger molecules with higher boiling points than ethane (e.g., octane, polyalkalene gl yc ol ). It seems more likely , as one commenter suggested , that these flammable fluids woul d 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 fall s between the lower flammability limit of the two individual substances. The range of flammable mixtures of ethane and refrigerants HFC - 134a, HFO - 1234yf, and CO 2 is largest for CO 2 and is sim ilar for HFC - 134a and HFO - 1234yf (Besnard, 199 6 ) .*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 43 of 134 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 r efrigerant, as occurs in MVAC sy stems . Such t esting , 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 oC or higher for HFO - 1234yf and 800 oC 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 section s IV and V of the preamble, “What are the final use conditions and why did EPA finalize these use conditions?” and “Why i s 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 potentiall y available for use in MVAC sy stems . The use conditions established in the final rule require manufacturers to design the s ys tem to prevent leakage from refrigerant sy stem connections that might enter the passenger cabin, and to minimize impingement of re frigerant and oil onto hot surfaces. 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 decrea ses as temperature increases. The commenter stated that the proposed LFL of 6.2% may not be conservative enough. Response: EPA agrees that the LFL decrease s as temperature increases. However, for the anal ys is relied on for the proposed rule, we conside red an LFL relevant to the temperatures that might be expected in a collision or leak scenario and that would*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 44 of 134 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 oC (140 oF) and an LF L of 5.3% at 100 oC (212 oF) . If a passenger were exposed to temperatures this high in the passenger compartment for an y 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 se ction IV of the preamble , “What are the final use conditions and why

did EPA finalize these conditions?” , we believe that the flamm ability 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 condition s in this final rule are sufficient to manage risks of injury or adverse health effects caused b y HFO - 1234yf. Comment: Regarding the first proposed use condition that would limi t 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 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 actuall y increase overall risk b y increasing the risk of conveying smoke and fumes from the engine compartment into the passenger compartment in th e event of an accident.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 45 of 134 Some commenters suggested alternative language for the use condition to give greater flexibility in engineering responses to allow for difference s 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 th e engine compartment should be limited to “prevention of ignition caused b y 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 flamm ability risk . The commenter stated that this would be consistent with safety requirements of the National Highway Traffic Safet y 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 concentr ations of HFO - 1234yf in hy brid 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 I SO (Intern ational Organization for Standardization) standards in place of a specific*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 46 of 134 use condition. One commenter stated that electric terminals on hy brid 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 sy stem] and the battery pack , preventing an increase in refrigerant concentrations at the battery pack . One commenter s tated that it is difficult to establish generic SNAP use conditions for hy brid vehicles , and individual manufacturers need to understand particular design features of their hy brid vehicle s to ensure safe refrigerant application . Three commenters expressed concern for using HFO - 1234yf in h yb rid 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 effectivel y avoid the risk of explosive mixtures. Another commenter stated that HFO 1234yf would raise concerns in the field of batt ery cooling needed in electric vehicles because flammability

and chemical reactions would pose major risks, which could lead to legal consequences for OEM s . 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 level s of refrigerant concentration may exceed the LF L in proximity

to exhaust manifold surfaces or near hy brid or electric vehicle power sources. As discusse d 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 -*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 47 of 134 1234yf as a refrigerant in MVAC. Based on information provided by OEMs that manufacture h ybrid vehicl es , we conclude that there will be sufficient protection against fire risk and generation of HF in the engine compartment for h ybrid 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 evap orator (under the windshield) would also release it in a location far enough away from the battery

pack to keep down 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 onl y exceeded the LFL within ten centimeters of the leak or less (EPA - HQ - OAR - 2008 - 0664 - 0056.2), but the battery pack is ty

picall y placed more than ten centimeters away from the evaporator. EPA expects that OEMs will inclu de 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 respon d e d to EPA’s request for comment as t o whether the use conditions should apply onl y 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*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 48 of 134 sy stem, 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 condition s that specifi ed a r efrigerant concentration not to be exceeded. Comment: Severa l commenters stated that the proposed limits on concentrations of HFO - 1234yf in the engine compartment cannot be met, even h ypothetically, and that imposition of such a use condition would delay or even prevent the use of HFO - 1234yf. Other commenter s stat ed 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 desi gned to use this refrigerant. Response : EPA is not including in the final rule the proposed u se 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 have 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 conditions are necessary because established standards and practices would be adequate for safe use of HFO - 1234yf . Response: The use conditions referenced b y the commenters were established in a separate final rule, promulgated in 19 96 , which applies to all refrigerants used i n MVAC (see a

ppendix D to subpart G of 40 CFR part 82) . EPA has not proposed to*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 49 of 134 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 h elp reduce risks to the technician b y ensuring that the technician will handle the refrigerant properl y. In addition, these use conditions serve to prevent contamination of refrigerant supplies through unintended mixing of different refrigerants. For pur poses 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 - 123 4yf has provided these fittings to the Agency

and they are consistent with the draft SAE standard J639. In addition, the final rule retains the requirement for a warning label identifying the refrigerant, consistent with both the current (2005) edition of SAE J639 and the current draft version. Comment: Some commenters agreed with EPA’s proposal to have 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 sy ste ms if the discharge pressure can reach the burst pressure, not just those sy stems with pressure relief devices. Response: EPA is including as a final use condition the requirement that HFO 1234yf MVAC sy stems must have a high - pressure compressor cut - off s witch. The use condition requires a pressure relief device on the high - pressure side of the compressor for all MVAC sy stems using HFO - 1234yf , and so the compressor cut - off switch will be required for all s ys tems using HFO - 1234yf, as suggested by the comme nter. Comment : Several commenters supported the requirement for vehicle makers to conduct and maintain FMEAs. Other automobile manufacturers stated that the final*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 50 of 134 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 anal yz e all the way s in which parts of the MVAC sy stem could fail and identify how they will address those risks in design of the sy stem. In addition, keeping records of an FMEA is important to ensuring safe use because it doc uments that vehicle designers have co mplied with the safet y requirements of this rule. W e believe that it is necessary to retain this requirement as a use condition in order t o ensure that OEMs are required to anal yz e and address the risks and to document those efforts such that this analy sis is available to demonstrate compliance to EPA in case of an EPA inspection. In formation in the FMEAs complement s the use conditions of this rule and is useful for demonstrating compliance. Comment: A commenter requested that EPA specifically allow manufacturers to perform FMEA s according to equivalent standards developed b y organizations other than SAE (e.g., the International Organization for Standardization [I SO] , the German Institute for Standards [ DI

N ] , or the Japan Automobile Manufacturers Association [ JAMA ] ). Response: W e agree that standards from other standard - setting organizations may provide equivalent assurance of safe use . However , w e are not aware at this time of any*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 51 of 134 standards that do so . In order to ensure safe use of HF O - 1234yf, we would need to review an y 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 imped es 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 th i s 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 potentiall y available. Congres s 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 safel y, and with risks comparable to or less than those of other available substitutes for CFC - 12 in the MVA C 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 fire risk from*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 52 of 134 MVAC sy stems, in the absence of such standards from DOT, EPA would need to determine that HFO - 1234yf is unacceptable for use in MVACs. C. Environmental impacts 1. Ozone Depletion Potential Comment: Several c ommenters 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 “nearl y zero,” and one commenter requested that EP A 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 depletin g . Response: It is generall y agreed among scientists that substances that contain chlorine, bromine or iodine may have an o zone depletion potential while those that contain only

fluorine effectively

have no ODP. In particular, this is because the CF 3 radical produced from HFCs has negligible reactivity (Ravishankara et al., 1993); the*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 53 of 134 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 onl y 11 to 12 day s (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 s ingle bonds between atoms of carbon , and is thus more stable . A lthough HFO - 1234yf may be more unstable than HFC - 134a, EPA is not aware o f an y chemical reactions or decomposition pathway s that would cause HFO 1234yf or its breakdown products to lead to ozo ne 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 nearl y zero, we expect HFO - 1234yf to have negligible impact on the ozone layer and we are listin g 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 - ye ar time horizon. Some commenters noted the potential environmental benefits of having a lower GWP refrigerant available. Other commenters s tated that HFO - 1234yf would not be a solution to high global warming impacts because of environmental and health impacts of breakdown products , including HF, trifluoroac etic acid (TFA) , and aldehydes . Response: EPA continues to believe that the 100 - yrGWP of HFO - 1234yf is 4 , as supported b y the commenters . We further agree with the commenters who state that*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 54 of 134 there will be an environmental benefit if car manufacturers s witch to HFO - 1234yf from HFC - 134a, a refrigerant with a GWP of 1430 relative to CO 2 . We disagree with the commenters who claim that environmental and health impacts of breakdown products is a major cause for concern or will prevent HFO - 1234y f 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 COF 2 , carbon yl fluoride (and then HF and CO 2 ) and CF 3 COF, trifluoroacet ylfluoride (and then TFA); in contrast, HFO - 1234yf favors forming trifluoroacet ylfluoride (and then TFA) and does not decompose to carbon yl 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 sec tion VII .C.5, “Formation of Trifluoroaceti c Acid and Ecosy stem Impacts,” the projected concentrations of TFA , based on a conservative anal ys is, will be far below the level expected to cause an y adverse impacts on aquatic life. EPA agrees that the breakdown products from the decomposition of HFO - 1234y f will include aldeh ydes, but we disagree that this is a cause for concern. As part of the anal ys is of the atmospheric breakdown products of HFO - 1234yf, we found that worst -*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 55 of 134 case concentrations of formaldeh yde would reach 6 to 8 parts per trillion (pp t) on a monthly basis or an average of 3 ppt on an annual average basis, compared to a health based limit of 8 000 ppt , 17 i.e., a level that is roughl y 1000 to 2600 times lower than the health - based limit (ICF, 2010d). Acetaldeh yde levels would be even lowe r, 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 (I CF, 2010d). As discussed further below in sec tion VII . D.1 of the preamble , “Toxicity of HFO - 1234yf,” these concentr ations are one to three orders of magnitude less than ambient concentrations of formaldeh yd e and acetaldeh yde without the introduction of HFO - 1234yf (ICF, 2010d). Thus, aldehydes that would be decomposition products of HFO - 1234yf in the atmosphere would n ot contribute significantly

to adverse health effects for people on earth’s surface. Other fluorinated alternatives that are acceptable in the MVAC end - use , HFC 134a and HFC - 152a, also create fluorinated breakdown products, and there is not evidence to s how that those from HFO - 1234yf create significantl y 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 - 1234y f in the MVAC e nd - use , we do not believe those risks are greater than the risks posed by other acceptable alternatives.

17 T he 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 s ummary 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 .*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 56 of 134 3. Life c ycl e Emissions of HFO - 1234yf Comment: One commenter stated that HFO - 1234yf has the best global lifecycle climate performance (LCCP) and lower CO 2 [equivalent] emissions compared to other alternatives. However, another commenter stated that HFO - 1234yf has a lower thermody namic efficiency

than HFC - 134a and that its use could lead to increases in CO 2 and other air pollutant emissions. The same comm enter stated that there is no assurance that automakers would voluntarily add technologies to maintain current levels of MVAC efficiency when using HFO - 1234yf. Response: W e 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 Analy sis (LCA) or LCCP as metrics for climate impact , since it i s not clear that there is agreement in all industri al sectors or end use s on which of these measures is most appropriate in which situations or how the se metrics are to be calculated (SROC, 2005) . T he available information on efficiency , LCCP and lifecycle emissions for MVAC does not raise concern that the indirect climate impacts from HFO - 1234yf will cause significantl y 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 :  B ench testing for the Japan Automobile Manufacturers Association (JAMA) and the Japan Auto P arts Industry Association (JAPIA) found a s ys tem*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 57 of 134 efficiency (coefficient of performance) for HFO - 1234yf that is roughl y 96% of that for HFC - 134a (JAMA - JA P IA , 2008)

 LCCP anal ys is conducted by JAMA found that indirect CO 2 equivalent emissions from less efficient fuel usage due to use of the MVAC sy stem were a few percent higher for HFO - 1234yf and roughl y 20 to 25% higher for CO 2 , compare d to HFC - 134a (JAMA, 2008)

 JAMA’s L CCP analy sis 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 CO 2 ; in hotter cli mates like Phoenix, Arizona, HFC - 134a has higher total climate impact than HFO - 1234yf but slightl y lower climate impact than CO 2 ; and in all cases, HFO - 1234yf had the lowest total climate impact of the three alternatives. (JAMA, 2008)

 MVAC sy stems can be d esigned 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, an d changing the design of the evaporator. Optimized new MVAC sy stems using either HFO - 1234yf or CO 2 can reduce fuel usage compared to current MVAC sy stems 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 sy stems than in the past because of recent regulations. The Department of Transportation has issued*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 58 of 134 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 highl y likel y that automobile manufacturers will include MVAC sy stems optimized for efficiency in future models , regardless of the refrigerant used . Comment: Concerning an appropriate rate of emissions for estimat ing environmental impacts of HF O - 1234yf, three commenters recommended that EPA use 50 g per vehicle per ye ar total lifecycle emission rate . These commenters cit ed the work of Wallington et al. ( 2008 ) and Papasavva et al. ( 2009) . 19 Another commenter stated that HFO - 1234yf is very

likely to have a lower leak rate than HFC - 134a , citing data on permeability

for both refrigerants . Response: EPA agrees that the permeability data indicate that regular leakage emissions of HFO - 1234yf , which is released slowly through hoses , is likel y 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 sy stem, refrigerant loss during servicing, and refrigerant loss at the end of vehicle life . In resp onse to the commenters who suggested that we use an annual emission rate of 50 g/vehicle/y

r , we reexamined environmental impacts as part of our final environmental anal ys is (I CF, 2010 c ) using the recommended 50 g/vehicle/y r value and compared this to the i mpacts calculated assum ing 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 19 Papasavva et al. (2009) includes several sources of emissions of automobile refrigerant, includi ng regular leaks through hoses, irregular leaks, refrigerant loss during servicing, and refrigerant loss at end of vehicle life.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 59 of 134 51.1% less than the emission estimates used in our anal ys is at the time of proposal (ICF, 2009 ; I CF, 2010a; ICF, 2010c ). In either case, as described more full y in section V above and in sections VII. C.4 and VII. C.5 , below , the overall environmenta l impacts on generation of ground - level ozone and of TFA were sufficientl y low and the impacts of HFO - 1234yf are not significantly greater than those of other available substitutes for MVAC . For further information, see the IC F analy ses 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 (I CF, 2009) of environmental impacts of HFO - 1234yf. Other commenter s 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 prov ided in public comments (e.g., Luecken et al., 2009 and Wallington et al., 2009 20 ). Response: We proposed that HFO - 1234yf would be acceptable, even with a worst - case increase in ground - level ozone of >1 to 4%. In response to comments, EPA performed a new anal ys is 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 (SO 2 ) as a surrogate for the hydroxyl radical, OH - , and rather than making assumptions about the relative reactivity of compounds. Our revised anal ys is (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

20 Prepublication version of Wallington et al., 2010 (Docket item EPA - HQ - OAR - 2008 - 0664 - 0084.2)*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 60 of 134 case, rather than an increase of 1.4 to 4% as determined in our initial analy sis (I CF, 2009). This value also agrees with results from Kajihara et al., 2010 and Luecken et al., 2009. This revised anal ys is provides additional support that HFO - 1234yf will not create s ignificant 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 agre ed with this conclusion. One commenter provided a peer reviewed study that estimated the POCP of HFO - 1234yf to be 7 (Wallington et al., 20 10 ). 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 analy sis to incorporate reaction kinetics specific to HFO - 1234yf, consistent with Luecken et al., 2009, which avoids making an assumption of POCP . EPA’s revised anal ys is e stimates worst - case increases in ground - level ozone formation of approximately

0 . 1 % (I CF, 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 uncert ainty in the anal ys is, 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 fo r our proposed determination that the conditioned use of HFO - 1234yf does not present a significantly

larger risk to human health and the environment compared to HFC - 134a, and in many

cases likel y poses less risk. For further information, see the anal ys is of environmental impacts in section V of the preamble, “ Why is EPA finding*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 61 of 134 HFO - 1234yf acceptable subject to use conditions? ” and see the anal ys is in the docket (I CF , 2010b) . Comment: A commenter provided a link to a paper (Carte r, 2009) that found the max imum 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 p reviousl y 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 F R 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 Ecos ys tem Impacts Comment : Several commenters agreed with EPA’s proposed finding that the projected maximum concentrati on 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 sustai nability 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 . Anoth er commenter stated that HFO - 1234yf poses additional*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 62 of 134 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 ecos ys tem 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 1/800 th to 1/80 th 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 analy sis on TFA concentrations using the known reaction kinetics of HFO - 1234yf. The revised estimate of the worst - case TFA concentration in rainwater is approximately 17 00 n g/L, similar to the concentrations in Luecken et al. (2009) of 126 0 n g/ L and Kaj ihara et al. (2010) of 45 0 n g/ 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 anal ys is 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 1/80 th to 1/800 th of the NOAEL for the most sensitive plant species considered. Kajihara et al. (2010) pre dicted through modeling that in Japan, HFO - 1234y f use in all potential refrigeration uses would increase the TFA concentration in surface*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 63 of 134 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 roughl y twice those in rainwater. Thus, even with highl y conservative modeling that also considered accumulation in surface water, the concentrations of TFA are likel y 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 f

urther modeling anal ys is 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 17 00 n g/ L, similar to the concentrations in Luecken et al. (2009) of 126 0 n g/Land Kajihara et al. (2010) of 45 0 n g/ L (ICF, 2010 b ) . The se additional studies and analy ses indicate even less risk than the studies available at the time of proposal and thus provide further support that TFA emissions from MVAC sy stem will not pose a significant risk of aquatic toxicity or ecos ys tem impacts. We also note that EPA has an obligation to act on submissions in a timely manner under the Clean Air Ac t (§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 significantl y 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 SO 2 to sulfate ion, SO 3 - , as a prox y for the oxidation of HFO - 1234yf is*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 64 of 134 overly conservative becaus e a large portion of SO 2 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 SO 2 to SO 3 - as a prox y for th e oxidation of HFO - 1234yf likel y result s in overestimating TFA concentrations. This is because the sulfate particle is a condensation nuclei 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, TF A forms more slowly from HFO - 1234yf than sulfate forms from SO 2 (I CF, 2010b) . We have repeated the modeling using refined assumptions on emissions and the mechanisms by

whic h HFO - 1234y f might break down. This revised assessment (I CF, 2010 b ) found TFA concentrations roughl y one - thousandth those in the earlier assessment (17 00 n g/ L compared to 1,800 ,000 n g/ L in ICF, 2009) . This additional research provides stronger support fo r our conclusion that the degradation of HFO - 1234yf into TFA does not pose a significant risk of aquatic toxicity or ecosy stem impacts. Comment: S ome commenters disagreed with a statement in the IC F (2009) anal ys is 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 relat ed to TFA, was rather limited in seasonal water bodies. The commenters also stated that Benesch et al . (2002) conducted an experimental study

of the impacts of TFA on vernal pools, in which no impacts were observed.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 65 of 134 Response : The statement from I CF, 20 09 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 widel y 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 . (I CF, 2009) We note that the “exception” described in the analysis is an exception to the expectation that TFA wil l be diluted more in freshwater bodies that 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 that the NOAEL for the most sensitive aquatic species examined . D. Health and safet y impacts 1. Toxicity

of HFO - 1234yf Comment: Three commenters stated that there are no toxicity concerns with using HFO - 1234yf, and two commenter s noted that HFO - 1234yf is comparable to HFC - 134a in terms of human health effects. One commenter also stated that HFO - 1234yf does not*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 66 of 134 present a developmental toxicity or lethalit y risk. Six commenters stated that there are potential toxicity

concerns with use of HF O - 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 n ew MVAC sy stems in accordance with the use conditions in this final rule, does not result in significantl y greater risks to human health than the use of other available or potentially available substitutes, such as HFC - 134a or CO 2 . 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 ) . N OAEL s 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 an y other level in subchronic (13 - week) studies for both HFO - 1234yf and HFC - 134a (NRC, 1996; TN O, 2007 a). 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 onl y a weak correlation with carcinogenicity (Parodi et al., 1 982 21 ;

21 Predictive ability of the auto radiographic 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.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 67 of 134 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 b y the same test found no evidence of mutagenicity . Screening for carcinogenic potential in a genomics study did not identify

HFO - 1234yf as a likely carcinogen (Hamner Institutes, 2007) . A two - year cancer assay for HFC - 134a did not find evidence of carcinogenicity (NRC, 1996). EPA considers the results of developmental testing to date to be of some concern, but not a sufficient basis to find HFO - 1234yf unacceptable for purposes of this action under the SNAP program . In a developmental study on rats, cases of wav y ribs were seen in some devel oping 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 fin d an association between exposure to HFO - 1234yf and skeletal effects. T his two - generation reproductive study for HFO - 1234yf find s a NOAE L 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 rab bits exposed to HFO - 1234yf did not find effects on the developing fetus. However, some of the mothe r 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. T he development effects observed in the developmental study on rats are not significantl y different from the developmental effects observed for HFC - 134a . In

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.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 68 of 134 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, w e prepared our risk assessment for long - term exposure us ing 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 l onger - term, repeated exposure in that study w ould be the exposure pattern (though not necessaril y 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 a llowed under this action t o 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 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*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 69 of 134 index for HFO - 1234yf was only one - ha lf of the values predicted for HFC - 134a, and in so m e cases, onl y one - third of the HFC - 134a values, demonstrating from a health perspective that HFO - 1234yf is a viable alte rnative to HFC - 134a. Response: EPA agrees that adverse health impacts would not be expected to car occupants or to servicing personn el , so long as the use conditions of this rule are observed . However, EPA has issu ed a Significant New Use Rule under TSCA ( Octo ber 2 7 , 2010; 75 FR 65987) that would require submission of additional information to EPA prior to the manufacture, import or p rocessing of HFO - 1234yf for certain uses, including distribution in commerce of products intended for use by a consumer for the purpose s of servicing, maintenance and disposal involving HFO - 1234yf (e.g., “do - it - yo urself” servicing of MVAC s ys tems ) . 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 extr apolating from animals to humans

– ty picall y a factor of 10 is used but, in this case, since there was a reasonable estimate of the pharmacokinetic component of the uncertaint y, this UF was reduced to 3. An additional UF is applied to account for variatio n 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*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 70 of 134 TSCA is to divide the POD by the exposure level to obtain the MOE . F or 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, i f the exposure is less than the POD, the HI is <1 and th e commenter considered this an “acceptable level of health risk.” T he commenter’s approach to the hazard index does not factor in uncertainties about extrapolating from animal to hum an 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 ce rtain 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. An y of these approach es 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 estimate s . The Agency

and the commenter disagree on all three of these inp uts to the risk assessment and hence have reached different conclusions . Despite these differences, the assessments relied on b y both the commenter and EPA show that there is low risk both to car occupants and to service technicians. EPA’s risk a ssessment indicate s a potential risk*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 71 of 134 to DIYers ( EPA - HQ - OAR - 2008 - 0664 - 0036) . As stat ed 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 commenter s dis agree d 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 ve ry short durations

– on the order of 10 minutes

– and th ey 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 inhalati on study on HFO - 1234yf , reasoning that if no effects were seen in the duration of the study (6 hours per day , 5 day s per week for 2 weeks) , that no effects would be seen from a single exposure at a similar exposure level , either . Further, the subacute exp osure 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 . T hu s 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 L OAEL of 20 0 , 0 00 ppm, it would have required an*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 72 of 134 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 usin g the NOAEL from the 14 - day subacute study. Inthe 4 - hour acute toxicity study , s ome 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 expo sure 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 expo sure levels for humans. If we had used the value from the 4 - hour acute toxicity study , we would have had to consider additional uncertaint y 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 fro m 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 developme ntal study . For th ese reason s , EPA recommended an acute inhalation toxicity study on rabbits in the proposed*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 73 of 134 SNUR to address th e question of whether pregnant rabbits would die from a single exposure (April 2, 2010; 75 FR 16706 ). Comment : A commenter as serted that EPA’s methodology to estimate the exposure levels associated with the DIY use , using the SAE CRP (2008) Phase II Report, greatl y 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 comm ente r stated that the 30 minute time weighted average ( TWA ) value used b y 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 an y l eaking 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 clo sed garage with no ventilation; and, • the amount of refrigerant used during recharge operations.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 74 of 134 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 ( Honey well, 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 anal ys is assumes a longer - term, steady - state concentration after the refrigerant has diffused throughout the garage and uses a lon g 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 ty picall y a DIY consumer will only need a short period of time to recharge a single MVAC sy stem (Clodic, 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 r esponded with a list of clarifying questions (US EPA, 2010 c ) , to which*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 75 of 134 the submitter subsequently responded ( Honey well , 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 c ontain ers, 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 contain ers. We further note that the Agency would anal yz e 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 b y DIYers, we make the following observations about the submitted study . With regards to exposure, the peak concentration values from the s ubmitted 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. Accordingl y, EPA would need exposure d ata presented and averaged out over shorter Time Weighted Averages ( TWAs ) than the 30 minutes currentl y in the study , because i t would appear that a number of th e se 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 .*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 76 of 134 EPA expects that exposure data with a dditional 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 sy stem . The commenter cited a diagram of breakdown produc ts in a slide presentation given by the Montreal Protocol Scientific Assessment Panel in July 2009 and suggest ed that the toxic impact of aldehydes formed as breakdown products would be higher than that of carbonic acids. Response : EPA agrees that the b reakdown products from the decomposition of HF O - 1234yf will include aldehydes , but we disagree that this is a cause for concern. The aldeh ydes that would be produced as atmospheric breakdown products of HFO - 1234yf are formaldeh yde and acetaldeh yde ( IC F, 2 010d). Their health effects include respiratory effects; irritation of the eyes, nose, and throat; and corrosion of the gastrointestinal tract. EPA also considers formaldeh yde and acetaldeh yde to be probable human carcinogens (US EPA, 2000; I CF, 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 anal ys is of the atmospheric breakdown products of HFO - 1234yf, we found that worst - ca se 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 8 000 ppt23

—i.e., a level that is roughl y 1000 to 2600 times lower than th e health - based limit (I CF, 2010d). Acetaldehyde levels would be even lower, with worst - case concentrations of 1.2 ppt and annual average concentrations of 0.23 ppt,

23 T he 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 (I CF, 2010d). MRLs are available at http://www.atsdr.cdc.gov/mrls/mrls_list.html .*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 77 of 134 compared to a health - based limit of 5000 ppt24 (ICF, 2010d). Thus, aldeh ydes that would be decomposition products of HFO - 1234yf in the atmosphere would not contribute significantl y to adverse human health effects (I CF, 2010d). Aldehydes, including formaldehyde and acetaldehyde, are already present in 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 formaldeh yde 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 formaldeh yde from HFO - 1234yf (ICF, 2010d). The maximum incremental acetaldeh yde 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 no t likel y 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 subm issions in a timely manner under the Act (§612(d)). O ur 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 . W e belie ve these assessments are sufficient

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 ass essment and RfC derivation for acetaldehyde is available online at http://www.epa.gov/ncea/iris/subst/0290.htm .*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 78 of 134 to support this action. We note that these assessments rel y 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 - 1234y f is not expected to be introduced into any new cars until late 20 1 1 or later, we exp ect to have further information and to take further action before DIYer could be exposed. In addition, the final SNUR would not allow distribution in commerce of products intended for use b y a consumer for the purposes of servicing, maintenance and dispos al involving HFO - 1234yf until at least 90 day s after submission of a SNUN. We recognize that more studies will be performed on HFO - 1234yf, further addressing risk . EPA’s New Chemicals Program ha s recommended additional testing o f 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 al lows 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 effe cts. The same commenter noted*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 79 of 134 that information on new price levels and availability is needed to assess the effectiveness of the SNUR. Response: EPA ’s final SNUR address es potential risks to human health from exposure to HFO - 1234yf. However, a s discuss ed 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 b y D IYusers , 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 a ppendix D to s ubpart G of 40 CF R p art 82 requi re the use of unique fittings for specific purposes (e.g., hi gh pressure - side service port , small can taps) for eac h MVAC refrigerant, as submitted by the refrigerant manufacturer. Before HFO - 1234yf can be introduced in small containers t ypicall y 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 rule s specifying those fittings. In addition, the final SNUR would not allow distribution in commerce of products intended for use b y a consumer for the purposes of servicing, maintenance and disposal involving HFO - 1234yf until at least 90 day s after submission of a SNUN. These and other requirements ensure – to the extent possible, with the information currently

ava ilable 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 (S NUN) with additional information on consumer exposure risks before

– if the Agency so decides

– HFO - 1234yf may be manufactured,*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 80 of 134 imported or processed for the purpose of use in DIY servicing , with or without other restrictions . W e would also consider info rmation 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 commente rs 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 co nsumers during DIY servicing, while other commenters stated more broadl y 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 - 00 77 .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 b y 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 an y risk s 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 o f ignit ion , especiall y under the conditions encountered in an automotive application. One*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 81 of 134 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 inf ormation 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 present a significant risk of flammability and that an y ri s k it poses is not greater than the risk presented b y other available alternatives. For example , b ecause of its higher LFL , its considerabl y high er 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 analy sis 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 ye ars across the entire U . S . fleet of passenger vehicl es ). 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 probabilit y 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 passeng er compartment. In a sensitivity*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 82 of 134 anal ys is , 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 sy stem. That analy sis estimat ed 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 section s 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 an y restrictions to protect those persons handling HFO - 1234yf

, n or 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 LF L of 6. 2% as a use condition. Based on comments and additional anal ys is, EPA has concluded that it is not necessary to require use condition s limiting refrigerant concentrations to below the LFL ; rather , the use conditions now specify design parameters for MVAC sy stems and require an FMEA . This will ensure*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 83 of 134 that sy stems are designed to minimize risk not only from flammability , but also from exposure to HF. W e will address use b y service personnel through a rulemaking under section 609 of the CAA. Although thes e rules will further address issues of interest to service personnel and others that might handle HFO - 1234yf used in MVAC sy stem s, we note that our risk assessments of use of HFO - 1234yf found that significant flammability risks do not exist for personnel i nstalling 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 anal ysis of risks found the risk of ignition of HFO - 1234yf to a technician is extremely

small, on the order of 10 - 2 6 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 us e (t ypi cally 20 lbs or larger) and thus HFO - 1234yf may not be use d in small container sizes that would be the ty pe 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 reque st 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 ( Octo ber 2 7 , 2010; 75 FR 65987 ) . Comment: One commente r 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 fuer Materialforschung und

– pruefung , BAM) . Other commenters disa greed with those flammability conclusions, finding the*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 84 of 134 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 - 123 4yf and ethane used in the testing would not be seen in MVAC in actual operations. Response: As explained above in sec tion VII . B , we do not believe that these tests are relevant for assessing the flammability risks of HFO - 1234yf as used in MVAC sy stems b ecause they

evaluated flammability

based on the presence of ethane, a substance that should not be present in an y situation that might cause flammability risks for MVAC s ys tems .

3. Toxicity

of Hydr o gen Flu o ride ( HF ) Comment : Two commenter s stated that the re is low risk of exposure to HF. One of these commenter s stated that (1) for vehicles that do not discontinue the use of the blower after collision, the risk of 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 of implementing HFO - 1234yf due to exposure to HF is approximately the same as that with the current use of HFC 134a (on order of 10 - 12 occurrences per operatin g hour, or one in one trillion) . The second commenter stat ed 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 . On e 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 expose d to excessive concentrations from an open hood.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 85 of 1 34 Other commenters s tated that that there is a high proba bility of HF generation in cars from HFO - 1234yf. One commenter stated that the flammability of HFO - 1234yf makes the production of HF more likel y 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 safet y 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 o f scenarios that might cause workplace and consumer exposure to HF (EPA - HQ - OAR - 2008 - 0664 - 0056.2) . SAE CRP members conducted tests to measure HF concentrations and to identify factors that were most likely to lead to HF formation. One set of tests conduct ed 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 highl y conservative scenario. (A more ty pical 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 test s focusing on HF in the engine compartment tried to simulate a major rupture in the AC s ys tem that would release 12 g/s of refrigerant across 5 cm onto an artificial hot surface at temperatur es of 450 oC (t ypical of the exhaust manifold) and 700 oC (most extreme case) , with the car hood in various positions . This*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 86 of 134 testing found HF concentration s as h igh as 120 ppm at the hot surface i n the engine compartment in the worst case, with interior pa ssenger 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 trial s under less extreme conditions resulted in HF concentrations of a few ppm. The test trial s 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 irri tation could still occur. Thus, even assuming a passenger inside a vehicle was exposed to HF at the highest level found in the test of 80 ppm , exposure at this level would at worst cause discomfort and irritation, rather than permanent or disabling health effects. For both HFO - 1234yf and for HFC - 134a, HF concentrations in the passenger compartment fell between the level that would protect against all adverse health effects (AEGL - 1 of 1.0 ppm for 10 minutes to 8 hours) and the level that would protect aga inst irreversible or disabling health effects (AEGL - 2 of 95 ppm over 10 minutes) (NRC,

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 .*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 87 of 134 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 th e risk level presented by HFO - 1234yf to be similar to that of the refrigerant currentl y being used b y automobile manufacturers , HFC - 134a . T herefore, there is no reason to regulate HFO - 1234yf more stringentl y to protect against HF exposure than for HFC - 134a. Comment : One commenter stated that test ing with HFOs commissioned by the environment al organization Greenpeace in 2001 hinted at a multitude of decompositio n products with high reactivity . The commenter stated that apparently even lubricants (polyalkyl ene gl ycol -- PAG) break down to HF when in contact with HFO - 1234yf in a M VAC sy stem . Th e commenter further expressed that BAM testing show ed that burn ing HFO - 1234yf resulted in concentration s of HF greater than 90 ppm in the engine compartment . The commenter concluded that the tests prove that in a standard s ys tem 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 condition s 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 th e releas ed substance reached 600 0 C and HF concentrations of over 90 ppm were measured in the engine compartment . According to a risk assessment from an automobile manufacturer, s uch a high temperature is un likely and could only be*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 88 of 134 achieved on the exhaust manifold under heav y engine load s 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) . Itis not clear what the conditions were for the study mentioned b y the commenter . Fo r 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 - 0 118.1 ). Italso is not clear if the compressor fan was operating during the test. During normal vehicle operation, the fan would cool down the compressor and the engine compartment, avoiding the temperature of 600 ° C on hot surfaces in the engine. Other tests have found that HF concentrations in the engine compartment were approximately

5 ppm or less and only

in the worst case (hot surface temperature of 700 ° C, closed hood on engine compartment) did HF concentrations attain a value o f 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 1 0 - minute average and is lower than the AEGL - 3 for HF of 170 ppm on a 10 - minute average , the value that would protect ag ainst life - threatening exposure but would not necessaril y prevent long - term health effects . However, we note that we do n o t 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 p rofessional first responders have training in chemical hazards and pos sess appropriate gear which would prevent them from receiving HF expo sures above health - based limits (EPA - HQ - OAR -*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 89 of 134 2008 - 0664 - 0056.2) and an interested by - stander would quickly back away

from a fire or from irritating HF vapors, thus prevent ing 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 results in fatalities. We f urther note that the HF concentrations found in the passenger compartment were lower than the health - based l imit, the AEGL - 2 of 95 ppm over 10 minutes. We also note that the risks presented b y HFO - 1234yf are not significantly different than the risk posed by HFC - 134a, the refrigerant currentl y in use in MVAC sy stems. M ixtures 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 o 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, c ould 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 (E PA - 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,*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 90 of 134 another acceptable refrigerant for MVAC, since this compound contains fluo rine , it present s 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 safet y features of MVAC sy stems using HFO - 1234yf and by requiring risk anal ys is for each car model through FMEAs . Comment: A commenter provided results from a test by I BExU on the decomposition of HFO - 1234yf under heat (EPA - HQ - OAR - 2008 - 0664 - 00 53. 3 ) . This commenter strongl y warned against a decision in favor of HFO - 1234yf because it would form highl y toxic HF when burning . T hree 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 Enviro nmental Agency (Umweltbundesamt

— UBA ) . Response: T he IBExU testing of HF generation from HFO - 1234yf is not relevant to assessi ng the risks of HFO - 1234yf as a refrigerant in MVAC. Laboratory tests concerning the nature of HF generation on hot surfaces found that this depend s on the contact time of reactants on the hot surface, the temperature of the hot surface and the movement o f refrigerant in diluted concentrations due to airflow ( EPA - HQ - OAR - 2008 - 0664 - 0056.2 ; EPA - HQ - OAR - 2008 - 0664 - 0 116.2 ) . The IBExU testing involve d heating the refrigerant steadily

in a sealed flask. Thus, the contact time in that test was far greater*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 91 of 134 than wou ld occur in an engine compartment and the movement of refrigerant in that test was essentiall y zero, unlike in an engine compartment where there would be constant air movement . Comment: Another test from BAM reported b y UBA examined HF formation from HF O - 1234yf and from HFC - 134a (EPA - HQ - OAR - 2008 - 0664 - 0080.1) . Fift y 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. T he study

also found that when HFO - 1234yf was mixed with 3% oil, it exploded at 600 ° C. The commenter stated that handl ing of HFO - 1234yf in the presence of hot metal surfaces results in HF formation in concentrations far above allowed workplace concentrati ons. Response: These results are not consistent with results from hot - plate tests conducted b y an automobile manufacturer and b y a chemical manufacturer for the SAE CRP ( EPA - HQ - OAR - 2008 - 0664 - 0056.2 ; EPA - HQ - OAR - 2008 - 0664 - 0115.1). Those manufacturers found that neither HFO - 1234yf nor HFC - 134a alone ignited at 900 ° C. One of these test s found that HFO - 1234yf mixed with PAG oil combusted starting at 730 ° C, while HFC - 134a mixed with PAG oil ignited at 800 ° C and above; the other test observed no ignition of a blend of each refrigerant with PAG oil at 800 ° C, but both blends ignited at 900 ° C. Based on the lack of reproducibility of the specific ignition temperature, it appears that the specific ignition temperature may depend on variables in the testing (e.g. , flash point of the oil used, amount of mixture used, angle of application, and air flow available). This information also shows that mixtures of refrigerant with compressor oil can combust at lower temperatures than pure refrigerant and that mixtures*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 92 of 134 of HFO - 1234yf and oil and mixtures of HFC - 134a and oil present similar risks of ignition and HF generation. Thus, we conclude d 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 b y 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 e ntire 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 deplo ym ent of an airbag during a vehicle collision (EPA - HQ - OAR - 2008 - 0 664 - 0056.2). E. Retrofit usage Comment : Several commenters stated that HFO - 1234yf should be used 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 proce ss. 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 sy stems 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 s ys tems currently using HFC - 134a with HFO - 1234yf.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 93 of 134 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 us e conditions in new MVAC sy stems and evaluated its risks only for use in new s ys tems. We will consider the retrofit use of HFO - 1234yf in MVAC sy stems if we receive a submission that specificall y 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 note that our rul e makings under SNAP do not require use of an y specific substitute. Rather, under SNAP, we have established lists of substitutes that are acceptable for use in various end use s (such as for MVACs) and end - use rs are free to choose which substitute to use, but must do so consistent with any use conditions that apply . As stated in the rul e 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 clearl y more harmful to human health and the environment than other alte rnatives.” 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 b y “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*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 94 of 134 studies and testing in the docke t 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 - yourselfer s are of potential concern (EPA - HQ - OAR - 2008 - 0664 - 0036 and EPA - HQ - OAR - 2008 - 0664 - 0038). In both document s, 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 onl y 2 to 3 times higher than the exposure predicted for that use (the “margin of exposure”). O ur risk assessment indicated a higher, more protective margin of exposure of at least 30 was needed to account for uncertaint y in the extrapolation from animals to humans and for variability

in the human population. In other words, we found th at 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 e quivalent 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 servici ng 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 thes e containers would not be purchased b y DIYers because of their expense ($800 or more per*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 95 of 134 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 re quested to review unique fittings for a smaller container size. In addition, EPA is further address ing th e issue of risks to DIYers in the Significant New Use Rule for 1 - propene 2,3,3,3 - tetrafluoro - (75 FR 65987 , Octo ber 2 7 , 2010) . This SNUR requires submission of a SNUN at least 90 day s before s a l e or distribut ion of products intended for use b y 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 - 1 2 in new MVAC sy stems did not propose to establish use conditions for servicing vehicles by certified professionals, but our anal ys es indicate that there is not significant risk to certified professionals, because HFC - 134a, which is currentl y used in most MVAC sy stems, presents similar risks and professionals have the knowledge and equipment to mitigate an y risks. We plan to further address servicing b y professionals when we develop a new rule under section 609 of the Clean Air Act for servicing and mainte nance of MVAC sy stems. Comment : Some commenters supported prohibiting sale of HFO - 1234yf in small containers. Other commenters state d that onl y 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 H FO - 1234yf. If an yone i s interested in us ing HFO - 1234yf in small cans or other small container s , they would need to contact the refrigerant manufacturer to submit unique fittings for approval under the SNAP program.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 96 of 134 Thus, under this final rule, we believe that onl y certified te chnicians will purchase HFO 1234yf because the larger containers are likel y to be prohibitively expensive for individuals performing DIY servicing ($800 or more for a 20 lb cylinder) and are likel y to be too large for most individuals to use, containing en ough refrigerant for 10 or more charges. We also note that in a separate final rule under the authority of TSCA ( Octo ber 27 , 2010; 75 FR 65987 ), EPA requires among other things, that notice must be given to EPA 90 day s before (1) HFO - 1234yf is used commerc ially other than in new passenger cars and vehicles in which the charging of motor vehicle air conditioning s ys tems with HFO 1234yf was done b y the motor vehicle OEM or (2) sale or distribution of products intended for use b y 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 sy stems at a significantly higher cost . This commenter stated that millions of lower income motorists may

be forced to go without air conditioning each ye ar or may seek out lower - cost alternatives such as propane or HFC - 152a. Response: While this final rule effectivel y prohibits DIY use beca use the final use conditions do not include unique fittings allowing for use with small refrigerant containers, we are not making an y final determination about whether HFO - 1234yf may be safel y used b y 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 submission s when we receive one . We note that because it is*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 97 of 134 unlikely that an y cars will have MVAC s ys tems with HFO - 1234yf before the 201 3 model ye ar, 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 s ys tem on a model ye ar 2013 vehicle. The separate final Significant New Use Rule that the Agency has issued under TSCA (75 FR 65987 ; Octo ber 27 , 2010) requires submission of a Significant New Use Notice at least 90 day s 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 refrigerant in an MVAC sy stem with a different substitute refrige rant. G. Servicing issues Comment: Several commenters stated that appropriate training and certification should be required to purchase HFO - 1 234yf for use in MVACs . Four commenters also stated that the final regulation should include a provision requi ring proof of certification in order to purchas e HFO - 1234yf , and recommended that current AC sy stems tests (i.e., for CAA section 609 certification) be updated. Some commenters dis agree d 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 serviced shops should be all owed to be certified . The commenter also questioned who will monitor “certified” technicians emplo ye d by dealerships that may do work on*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 98 of 134 the side . A commenter representing automobile dealerships specificall y opposed mandatory

requirements for certificati on 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 purcha se CFC - 12 or other ODS for use in MVAC (40 CFR 82.34(b)) . Section 609 (e) of the CAA itself specificall y prohibits sale of small containers less than 20 pounds with Class Ior Class II substances suitable for use as a refrigerant in MVAC, except for indivi duals 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 Ior Class II ODS, such as HFO - 1234yf. In the NPRM (7 4 FR 53449), EPA stated that an y specific training and certification requirements would be adopted through a rulemaking under the authority of CAA section 609 and would be codified in 40 CFR part 82 subpart B, which contains the regulations implementing se ction 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 properl y 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 - 1 34a 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 significantl y greater than those of other available substitutes.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 99 of 134 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 an y other CAA regulation would limit servicing to dealerships. The comment may

concern the withdrawn SNUR, 75 FR 4 983 (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 ( Octo ber 27 , 2010; 75 FR 65987 ) requires a significant new use notice to EPA at least 90 day s before “ commercial use other than in new passenger cars and vehicles in which the charging of motor vehicle air conditioning sy stems 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 sy stems. 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, stat ing that because dealerships already train technicians on flammable substances in accordance with hazard communication standard s of the Occupational Safety and Health Administration (OSHA), and since the risks associated with HFO - 1234yf are similar to tho se that already exist in MVAC service facilities, mandatory training and proof of training is not necessary . To*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 100 of 134 enable training pursuant to the OSHA hazard communication standard , the commenter stated that MVAC sy stem and refrigerant suppliers should prov ide dealerships with sufficient information on the hazards posed b y 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 r equiring technician training and does not refer to specific training standards. We agree with the commenter that current technician training generall y should be sufficient to ensure that professional technicians will use HFO - 1234yf safel y. 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. E PA 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 requir ed in the servicing of MVAC sy stems using HFO - 1234yf, including recycling and recovery . Further, EPA notes that Section 608 of the CAA prohibits the intentional release of an y refrigerant during the maintenance, repair, service, or disposal of refrigerati on and air conditioning equipment, unless the Administrator*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 101 of 134 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 ris k to human health and the environment” b y 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 adequatel y. The same commenter stated that EPA’s environmental analy sis is based on price assumptions that were not disclosed and are no longer valid, and thus, EPA should subpoena the information from the manufacturer and reopen the public comment period. Response: EPA believes that ther e was sufficient information in the record at the time of proposal for us to complete a meaningful environmental anal ys is, even in the absence of definitive cost information. At the time of proposal, we had available both estimates from a trade magazine p rovided b y 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 inf ormation and thus were not available in the record to the public. We ty picall y 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,*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 102 of 134 because the automobile industry tends to prefer use of a single substitute, information on the cost of the substitute was not critical to our analy sis. Thus, in conducting our environmental anal ys is, we took a conservative approach, assuming that all new MVAC sy stems began using HFO - 1234yf b y 2020 (i.e., full market penetration). We also considered an even more conservative scenario, in which HFO - 1234yf would be the only refrigerant u sed for stationary air conditioning and for refrigeration as of 2020, as well as for MVAC. Even with these highl y 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 recent ly , the first automobile manufacturer announcing its intension to use HFO - 1234yf confirm ed that this range does not underest imate 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 monopol y would result in significantl y different, higher costs that would invalidate EPA’s earlier anal ys is. Inany event, assuming that costs were higher as suggested b y the commenter, then we expec t that use of HFO - 1234yf would be less than assumed for our health and environmental risk analy sis. 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 b e expected to be less under a scenario with higher prices and less use of HFO - 1234yf. Our analy sis assumes widespread use and thus its results would be protective.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 103 of 134 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 availabil ity

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 predi cting market penetration and thus how much of a particular substitute may be used and thus pose an environmental risk. As we did for HFO - 1234yf, we ty pically take a environmentally - protective approach to our evaluation, assuming use at least as high as th at 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:*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 104 of 134 ...It shall be unlawful to replace any class I or class I I substance with an y 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

—

(1) reduces the overall risk to human health and the envi ronment; and (2) is currentl y or potentially available.... (emphasis added.) This section makes clear that it is not the substitute under review that must be available or potentiall y available, but rather alternative replacements for ODS that EPA determines pos e 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 currentl y or potentiall y 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 ty

pes of listing decisions EPA can make in reviewing substitutes 26 ). We note th at even if EPA w as 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

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 im pacts. Cost and avai lability 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. I n this case, we assumed that HF O - 1234y f would be used widely across the industry in ne w MVA Cs 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.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 105 of 134 potentially

available . EPA’s definition of “potentially available” at 40 CFR 82.172 provides: Potentially

available is defined as any alternative for which adequate health, safet y, and environmental data, as required for the SNAP notification process, e xist to make a determination of acceptability , and which the Agency reasonably believes to be technicall y 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 n ot 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, safet y and environmental d ata adequate to make a determination of acceptability , and for the Agency

to reasonabl y believe that the alternative is “technically feasible, ” in order for the alternative to be potentially available. We believe the record contains adequate information s howing that HFO - 1234yf 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 c hemical 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 protectivel y assumed widespread use that would result in more emissions and greater environmental impacts .*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 106 of 134 In addition, b ased on the experimental work conducted b y the automobile industry , we reasonabl y believe that HFO - 1234yf is technicall y feasible as a refrigerant. Thus, HFO 1234yf would still be “potentially available” under the SNAP program’s definition. One commenter points to Honeywell International, Inc. v. EPA , 374 F.3d 1363 in urging EPA to explicitly

include cost as a consideration in determining whether a substitute is “potentially

available.” In that case , the court vacated and remanded a SNAP decision in which EPA listed a foam blowing substitute as acceptable subject to “narrowed use limits” on the basis that for some niche foam blowing uses, the substitutes that were already listed as acceptable might not be available. Under the narrowed use limits , the end - use r would need to demonstrate and document that other substitutes we re not technicall y 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 onl y to the substitutes against which the substitute at issue is being compared. Th e Agency has not deci ded 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 r eview. However, we note that for purposes of the substitute under review, the Agency firmly believes that cost*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 107 of 134 should not be the primary or sole basis for finding a substitute unacceptable. EPA’s role is to determine the health and environmental risk ass ociated with the use of substitutes and the market should serve to address the issue of costs. C osts will necessarily be a factor considered b y the automobile manufacturers in deciding which substitute to use . Comment : Two commenters stated that EPA nee ded to perform further analy sis 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 likel y 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 - 1234y f. The other commenter mentioned the costs to service and repair shops, end - of - life vehicle recyclers, and automobi le dealerships, and stated that EPA needed to anal yz e costs to these small businesses under the Regulatory Flexibility

Act. This latter commenter stated that EPA should determine if a significant change in price and supply expectations would affect the way that these businesses handle and deal with automobile repairs and recycling. Response: The RFA applies only when there are small entities subject to the requirements of the proposed or final rule. 5 U.S.C. § 604(a)(3). We believe the potential burden of complying with RCRA regulations placed on those recycling or recovering a substitute is generall y not pertinent to a decision of whether HFO - 1234 yf should be found acceptable under SNAP . To the extent the commenters are suggesting*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 108 of 134 that we must evaluate such costs for purposes of the Regulatory Flexibility

Act, we note that under the RFA we evaluate costs imposed b y the enforceable regulations being promulgated. To the extent the costs referred to by the commenter are already imposed under RCRA, they

wo uld not be new costs, but costs associated with the relevant RCRA regulations. Moreover, under th is 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 sy stems, because they concern design o f MVAC sy stems. The one use condition of the rule that applies to servicing of MVAC s ys tems, 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 sub part G of 40 CFR part 82 already require unique service fittings as specified b y the refrigerant manufacturer. Thus, the costs of purchasing new unique fittings for this refrigerant are imposed b y the pre - existing regulation. This rule specifies the requ irements for the t ype of unique fitting, in accordance with the fittings provided to EPA by

the manufacturer. These fittings are proposed for adoption as part of the draft SAE J639 standard. It is not clear that there would be any cost differential betwe en 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.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 109 of 134 EPA notes that th ere 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 anal ys is of such costs, as necessary , as part of those future rulemakings. Comment: A commente r stated that to comply with requirements of the Unfunded Mandates Reform Act (UMRA), EPA needed to perform further anal ys is on the potential costs of EPA’s SNAP regulations for HFO - 1234yf to determine if the rule would result in the expenditure of $100 mi llion or more per ye ar b y the private sector. In particular, the commenter stated that EPA must obtain more information on pricing and the e ffect of the manufacturer’s patent to anal yz e 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 an y specific substitute for ozone depleting substances. Rather , through this action, we are expanding the choices of MVAC refrigerants available to the p rivate sector. T he issue raised b y 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 authorit y for the SNAP program? Section 612 of the Clean Air Act (CAA) requires E PA 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:*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 110 of 134 1. Rulemaking Section 612(c) requires EP A to promulgate rules making it unlawful to replace any class I (i.e., chlorofluorocarbon, halon, carbon tetrachloride, methyl chloroform, methyl bromide, and h ydrobromofluorocarbon) or class II (i.e., hydrochlorofluorocarbon) substance with an y 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 currentl y or potential ly 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/ o zone/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 40 CFR part 82 subpart G.

3. Petit ion Process Section 612(d) grants the right to an y 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 day s to grant or deny a petition. Where the Agency grant s the petition, EPA must publish the revised lists within an additional six months.

4. 90 - day

Notification Section 612(e) directs EPA to require an y person who produces a chemical substitute for a class I substance to notify the Agency

not less than 90 day s b efore new or*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 111 of 134 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 substitute s.

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 i n 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 pro cesses 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 fi rst lists identifying acceptable and unacceptable substitutes in the major industrial use sectors (40 CFR part 82, subpart G). These sectors include: refrigeration and air conditioning; foam blowing; cleaning solvents; fire suppression and explosion prot ection; sterilants; aerosols; adhesives, coatings and inks; and tobacco expansion. These sectors compose the principal industrial sectors that historically consumed the largest volumes of ODS.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 112 of 134 Section 612 of the CAA requires EPA to list as acceptable onl y 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 SNA P 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 safet y i nformation on the substitute at least 90 day s 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 ty picall y chemical manufacturers, but may also include importe rs, formulators, equipment manufacturers, or end - users 28 when they are responsible for introducing a substitute into commerce. The Agency

has identified four possible decision categories for substitutes: acceptable; acceptable subject to use conditions; ac ceptable 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 narrow ed use limits) can be used for all applications within the relevant end - use s within the sector. Substitutes that are acceptable subject to use restrictions may be used only

in accordance with those

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 comme rce 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 A s defined at 40 CFR 82.17 2 “end - use” means processes or classes of specific applications within major industrial sectors where a substitute is used to replace an ozone - depleting substance.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 113 of 134 restrictions. It is illegal to replace an ODS with a sub stitute 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 onl y if certain condition s 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 associated use condi tions 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 e nd - use s 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 b y 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 - use s that are not consistent with the narrowed use limit, are using these sub stitutes in an unacceptable manner and are 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 acc eptable subject to use restrictions (use conditions and/or narrowed use limits), or for substitutes deemed*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 114 of 134 unacceptable, as proposed rulemakings to allow the public opportunity to comment, before publishing final decisions. In contrast, EPA publishes sub stitutes 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 procedure s are necessary to list alternatives that are acceptable without restrictions because such listings neither impose any sanction nor prevent an yone from using a substitute. Many SNAP listings include “comments” or “further information” to provide additiona l 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 legall y 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 buildin g - codes or standards. Thus, man y 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 compreh ensive SNAP lists of substitutes or additional information on SNAP, refer to EPA’s Ozone Depletion web site at*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 115 of 134 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 40 CFR part 82, subpart G. 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. E xecutive Order 12866: Regulatory Planning and Review Under Executive Order (EO) 12866 (58 FR 51735, October 4, 1993), this actio n 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. Accordingl y, EPA submitted this action to the Office of Management and Budget (OMB) for review under EO 12866 and an y changes made in response to OMB recommendations have been documented in the docket for this action. B. Paperwork Reduction Act This act ion does not impose an y new information collection burden. Today's action is an Agency

determination. Itcontains no new requirements for reporting. The only new recordkeeping requirement involves customary business practice. Today's rule requires mini mal record - keeping of studies done to ensure that MVAC s ys tems 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 Anal ys is (FMEA) on an y potentially hazardous part or s ys tem 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*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 116 of 134 Management and Budget (OMB) has previousl y 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 numb ers 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) generall y requires an agency to prepare a regulatory

flexibility

analy sis of any

rule subject to notice and comment rulemaking requirements under the Administrative Procedure Act or an y 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 inclu de 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 NAI CS 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 , count y, 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 domin ant in its field. After considering the economic impacts of today's final rule on small entities, I certif y that this action will not have a significant adverse economic impact on a*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 117 of 134 substantial number of small entities. Th e only new requirement on small entities in this final rule is a requirement specifying the ty pe of unique service fittings required when servicing MVAC s ys tems using the refrigerant HFO - 1234yf. Existing regulations at a ppendix D to s ubpart G of 40 CFR p art 82 already require that there be unique service fittings for each refrigerant used in MVAC sy stems. 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 b y the manufacturer. These fittings are proposed for adoption as part of the draft SAE J639 standard. It is not clear that there would be an y cost differential between these specific unique fittings 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, b y a llowing them the flexibility to use a new refrigerant that otherwise would have been prohibited under previous requirements at appendix B to subpart G, 40 CFR part 82 and b y 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 syste ms using HFO - 1234yf

. EPA is simply listing HFO - 1234yf as an acceptable alternative with use conditions in new MVAC sy stems. 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*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 118 of 134 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 anal ys is, for proposed and final rules with ``Federal mandates'' that may result in expenditures to State, l ocal, 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 generall y requires EPA to identify and cons ider 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 applic able 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. Be fore EPA establishes an y regulatory requirements that may significantl y 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 noti fying potentiall y affected small governments, enabling officials of affected small governments to have meaningful and timely input in the development of*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 119 of 134 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 ag gregate, or the private sector in any one ye ar. Today's rule does not affect State, local, or tribal governments. The enforceable requirements of today 's rule related to sy stem design and document ation of the safet y of alternative MVAC systems af fect onl y a small number of original equipment manufacturers . Further, those requirements are consistent with requirements that the automotive industry is proposing to adopt through consensus standards of SAE International. We expect that most manufacturers of a utomobiles and MVAC sy stems 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 widel y than for original equipment manufacturers is a requirement specifyin g the t ype of unique service fittings required when servicing MVAC systems using the refrigerant HFO - 1234yf. Existing regulations at a ppendix D to s ubpart G of 40 CFR p art 82 already require that there be unique service fittings for each refrigerant used in MVAC sy stems. The fittings required in this final rule are proposed for adoption as part of the draft 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 ye ar. This actio n 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 ye ar. Thus, today 's rule is not subject to the requi rements of*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 120 of 134 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 directl y to facilities that use these substances and not to g overnmental 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, entit led ``Federalism'' ( 64 FR 43255 , August 10, 1999), requires EPA to develop an accountable process to ensure ``m eaningful 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 resp onsibilities among the various levels of government.'' This action does not have federalism implications. Itwill 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*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 121 of 134 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 . Itdoes not significantl y or uniquely

affect the communities of Indian tribal governments, because this regulation applies directl y 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 addressed by this action present a disproportionate risk to children. This action’s health and risk assessments are discuss ed in sections V and VII. D of the preamble and in documents EPA - HQ - OAR - 2008 - 0664 - 00 36 and HQ - OAR - 2008 - 0664 - 00 38 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 acti on” 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*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 122 of 134 manufacturing and repair of MVAC sy stems using an a lternative refrigerant. This rule does not mandate a switch to HFO - 1234yf. Preliminary information indicates that these new s ys tems are more energy efficient than currently

available s ys tems in some climates. Therefore, we conclude that this rule is not likely to have a significant adverse effect on energy suppl y, distribution or use. I. National Technology Transfer and Advancement Act Section 12(d) of the National Technology Transfer and Advancement Act of 1995 (“NTTAA”), Publi c Law No. 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 deci des 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 standard. This standard can be obtained from http://www .sae.org/technical/standards / . This standard addresses safety and reliability

issues in motor vehicle design, including MVAC s ys tems using alternative refrigerant s . J. Executive Order 12898: Federal Actions to Address Environmental Justice in Minority Populations and Low -Income Populations*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 123 of 134 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 b y law, to make environmental justice part of their mission by

identifying and addressing, as appropriate, dis proportionately high and adverse human health or environmental effects of their programs, policies, and activities on minority

populations and low - in come populations in the United States. EPA has determined that this final rule will not have disproportionatel y high and adverse human health or environmental effects on minority or low - income populations because it increases the level of environmental p rotection for all affected populations without having an y disproportionately high and adverse human health or environmental effects on an y population, including an y minorit y 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 d isproportionately

high and adverse human health or environmental effects on any population, including any minority or low - income population. This final rule require s specific use conditions for MVAC sy stems, if car manufacturers chose to make MVAC sy stems using this low GWP refrigerant alternative. K. Congressional Review Act The Congressional Review Act, 5 U.S.C. 801 et seq., as added b y the Small Busin ess Regulatory

Enforcement Fairness Act of 1996, generall y provides that before a rule may take effect, the agency

promulgating the rule must submit a rule report, which includes a cop y of the rule, to each House of the Congress and to the Comptroller Gene ral 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*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 124 of 134 Comptroller General of the United States prior to publication of the rule in the Federal Register. A Major rule cannot take effect until 60 day s 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 [ insert date 60 days after publication]. XI. References T he 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 N o. EPA - HQ - OAR - 2008 - 0664 at http://www.regulations.gov . Benesch et al., 2002. Investigation of Effects of Trifluoroacetate on Vernal Pool Ecosy stems. 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&S RETRY=0 Benouali et al. , 2008. “ A/C Sy stem Control Strategies for Major Refrig erant Options” June 11, 2008, Alternative Refrigerant Sy stems S ymposium Phoenix, AZ. Available online at http://www2.dupont.com/Refrigerant s/en_US/assets/downloads/SmartAutoAC/20 08_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/12 17583/files/CM - P00055900.pdf Boutonnet et al., 1999. Boutonnet, J.C., et al. "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 Analy sis on Emissions and Economic Impact of Proposed Regulation for Small Contai ners 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),*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 125 of 134 ti tle 17, sections 95360 through 95370. Available online at http://www.arb.ca.gov/regact/2009/hfc09/hfc09.htm . Carter, 2009. Investigatio n of Atmospheric Ozone Impacts o f 2,3,3,3 - Tetrafluorop ropene. Final report to Honey

well Internationl Contract UCR - 09010016. William Carter , University

of California, Riverside CA. June 2, 2009. Available online at http://www.cert.ucr.edu/%7 Ecarter/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 k base.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. L ansard. 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. Prep ared for SAE International Cooperative Research Program 1234 b y Gradient Corporation. February

26, 2008. Docket number EPA - HQ - OAR - 2008 - 0664 - 0008 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. Hamn er Institutes, 2007. Toxicogenomic a ssessment of the c arcinogenic p otential 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. Honey well, 2010a. Comment on EPA Proposed Rule (simulated vehicle service leak testing and exposure study). Docket ID: EPA - HQ - OPPT - 2008 - 0918 - 0088. Honey well , 2010b. Response to EPA questions. Docket ID: EPA - HQ - OPPT - 2008 - 0918 - 00 96 . IC F, 2008. ICF International. 2008. Air Conditioning Refrigerant Charge Size to Passenger Compartment Volume Ratio Analy sis . Docket number EPA - HQ OAR - 2008 - 0664 - 0003 IC F, 200 9. ICF International. 2009. Revised Final Draft Assessment of the Potential Impacts of HFO - 1234yf and the Associated Production of TFA on Aquatic*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 126 of 134 Communities and L ocal Air Quality . Docket number EPA - HQ - OAR - 2008 - 0664 - 0037 IC F, 2010a. ICF International . 2010. Summary of HFO - 1234yf Emissions Assumptions . IC F, 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 L ocal Air Quality . IC F, 2010c. ICF International. 2010. Sensitivity Analy sis CMAQ results on projected maximum TFA rainwater concentrations and maximum 8 - hr ozone concentrations. IC F, 2010d. ICF International. 2010. Analysis of Potential Impacts of Aldehydes as Breakdown Products from HFO - 1234yf. IC F, 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 Intergover

nmental Panel on Climate Change, 2007. Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Avery t, 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 . “L CCP Result from JAMA,” Japan Automobile Manufacturers Association , T. Ikegami; K. Inui; K. Aoki. VDA Alt ernative Refrigerant Winter M eeting , Saalfelden, Austria, February 13 - 14, 2008. Available online at http://www.vda winter meeting.de/fileadmin/downloads2008/presentations/Tohru_Ikegami_Toyot a_Kenta_Aoki_Nissan_JAMA.pdf (begins, p. 23) JAMA - JAPIA, 2008 . ”New Refrigerants Evaluation Results” Japan Automobile Manufacturers Association - Japan Aut o Parts Industries Association Consortium. T. Ikegami, M. Iguchi, K. Aoki, K. I ijima; VDA Alternative Refrigerant Winter M eeting , Saalfelden, Austria, February 13 - 14, 2008. Available online at http://www.vda wintermeeting.de/fileadmin/downloads2008/presentations/Tohru_Ikegami_Toyot a_Kenta_Aoki_Nissan_JAMA.pdf . Kajihara et al., 2010 . “Estimation of environmental concentrations and deposition fluxes of R - 1234 - YF and its decomposition products emistted from air conditioning equipment to atmosphere”. H. Kajihara, K. Inoue, K. Yoshida, R. Nagaosa. February 17 - 19, 2010. 2010 International S ymposium on Next - generation Air Conditioning and Refrigeration Te chnology . Docket number EPA - HQ - OAR 2008 - 0664 - 0114.1*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 127 of 134 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 R esearch , 584, 1 - 256. Available online at 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. 200 9 . 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 Sy st em Enhancements and Comparison to R - 134a .” 2008, Alternative R efrigerant S ys tems Sy mposium Phoenix , AZ Available online at http://www2.du

pont.com/Refrigerants/en_US/assets/downloads/SmartAutoAC/20 08_SAE_ARSS_Visteon_Eval.pdf Monforte et al., 2008 ”Updated situation about alternative refrigerant evaluation” June 10 - 12, 2008, Alternative Refrigerant Sy stems Sy mposium Phoenix, AZ. http://www2.dupont.com/Refrigerants/en_US/assets/downloads/SmartAutoAC/20 08_SAE_ARSS_Renault_Fiat_PSA_Eval.pdf Nielsen et al., 2007. Ni elsen, O.J., Javadi, M.S., Sulbaek Andersen, M.P., Hurley , M.D., Wallington, T.J., Singh, R. 2007. Atmospheric chemistry of CF 3 CF=CH 2 : Kinetics and mechanisms of gas - phase reactions with Cl atoms, OH radicals, and O 3 . 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#p2000a02f9960 127001 . Orkin et al., 1997. Rate constants for the reactions of OH with HFC - 245cb (CH 3 CF 2 CF 3 ) and some fluoroalkenes (CH 2 CHCF 3 , CH 2 CFCF 3 , CF 2 CFCF 3 , and CF 2 CF 2 ),*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 128 of 134 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. Ravishankaraa 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., 198 2. Predictive ability of the autoradiographic repair assay in rat liver cells compared with the Ames test ; S. Par odi; M. Taningher; C. Balbi ;L. Santi . J ournal of Toxicology and Environmental Health, Vol. 10 , I ssue 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 Hydrofluoroc arbons Destro y Stratospheric Ozone? A. R. Ravishankara, Andrew A. Turnipseed, Niels R. Jensen , Stephen Barone , Michael Mills , Carleton J. Ho ward , 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 - 0 664 - 0xxx. 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/M AC_VDA08_HFO_1234y f.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, L ambert Kuijpers, Susan Solomon, Stephen O. Anderson, Ogunlade Davidson, Jose Pons, David de Jager, Tahl Kestin, Martin Manning and*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 129 of 134 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 - 00 2 2 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 - 00 23 an d attachments - 0023.1 through - 0023.9. US EPA, 1994. U.S. Environmental Protection Agency (US EPA). 1994. Methods for derivation of inhalation reference concentrations and application of inhalation dosimetry . EPA/600/8 - 90/066F. Office of Health and E nvironmental Assessment, Washington, DC. 1994. Available online at http://cfpub.epa.gov/ncea/cfm/recordisplay .cfm?deid=71993 US 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 US EPA, 2010a. Email from Yaidi Cancel, EPA. To William Hill and Ward Atkinson, SAE Interior C limate Control Committee re: Minimum recordkeeping on SAE J1739. August 16, 2010. US EPA, 2010b. Email from Margaret Sheppard, EPA to Christopher Seeton and Kasia Bober, Honey

well re: Summary

of our conference call on service fittings for HFO - 1234yf. November 8, 2010. US EPA, 2010 c . Clarifying questions for Honey well on Exposure Study . Docket number EPA - HQ - OPPT - 2008 - 0918 - 0095 . Wallington et al., 2008. Emissions of CO 2 , CO, NO x , HC, PM, HFC - 134a, N 2 O and CH 4 from the Global Light Duty Vehicle Flee t. Meterolo. Z. 17. 109 - 116. Available online at http://www.schweizerbart.de/resources/downloads/paper_free/56618.pdf Wallington et al., 2010 . “Estimated Photochemica l Ozone Creation Potentials (POCPs) of CF3CF=CH2 (HFO - 1234yf) and Related Hydrofluoroolefins (HFOs).” T. Wallington, M. Andersen, O. Nielsen. Atmospheric Environment, in press 2010. Docket number EPA - HQ - OAR - 2008 - 0664 - 00 84.2. Available online at http://www.sciencedirect.com or at doi:10.1016/j.atmosenv.2010.01.040 . Weissler, P., 2008. “Consensus Building on Refrigerant Ty pe . ” Aut omotive Engineering*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 130 of 1 34 Protection of Stratospheric Ozone: New Substitute in the Motor Vehicle Air Conditioning Sector under the Significant New Alternatives Policy (SNAP) Program (Page 130 of 134 ) International. 9: 30 - 32. Docket numb er EPA - HQ - OAR - 2008 - 0664 - 0006. WI L, 2006. Acute Cardiac Sensitization Study of [name redacted] and HFO - 1234yf in Dogs. WIL Laboratories, 2006. Docket number EPA - HQ - OAR - 2008 - 0664 - 00 19 and attachments - 0019.1 through - 0019.2. List of Subjects in 40 CFR Part 82 Environmental protection, Administrative practice and procedure, Air pollution control, Reporting and recordkeeping requirements , Stratospheric ozone layer . Dated: ______________________________________

___________________________________________ __ Lisa P. Jackson, Administrator. For the reasons set out in the preamble, 40 CFR part 82 is amended as follows: PART 82 -- PROTECTI ON OF STRATOSPHERIC OZONE 1. The authorit y 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*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 131 of 134 2. The first table in Subpart G to Appendix B of Part 82 is amended b y adding one new entry to the end of the table to read as follows: Appen dix B to Subpart G of Part 82 - Substitutes Subject to Use Restrictions and Unacceptable Substitutes REFRIGERANTS - ACCEPTABLE SUBJECT TO USE CONDITIONS Application Substitute Decision Conditions Comments

***** CFC - 12 Automobile Motor Vehicle Air Conditioning (New equipment in passenger cars an d light duty trucks only) HFO - 1234yf

as a substitute for CFC - 12 Acceptable

subject to use conditions 1. The high - pressure side of the MVAC

system shall have a pressure relief device located in the high pressure side of the compressor or immediately adjacent t o the compressor discharge fitting. The device shall release refrigerant only outside of the passenger, trunk, and storage compartments and MVAC air distribution system. These pressure relief devices shall be designed to minimize impingement of the refrig erant and oil on hot surfaces. 2. The MVAC system high - pressure side relieve device identified above in 1 shall be self - sealing. In no case shall the maximum release (blow - of

f) pressure be greater than the maximum refrigerant working pressure. 3. To prevent unn ecessary discharge of refrigerant during operation, the system shall have a means to limit the compressor operation by cutting off transmission of power to the compressor before any component failure occurs and before activation of any pressure relief devi ce (i.e., compressor cutoff switch). 4. In no case shall any high - pressure side refrigerant pressure relief valves (or burst disks) have an activation pressure greater than the maximum working pressure of 4.14 MPa. Gauge (600 psig). 5. The maximum pressure on the low pressure side of the MVAC system shall not exceed the saturation pressure of HFO 1234yf at 56 o C. 6. HFO - 1234yf refrigerant systems connections shall either be:  Located outside the passenger compartment and outside the passenger cabin airflow

path. or  Designed to prevent leakage if the connections are located inside the Additional training for service technicians reco mmended. Observe requirements of Significant New Use Rule at 40 CFR 721.10182.*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 132 of 134

passenger cabin or in the passenger cabin airflow path. For safety reasons, individuals performing servicing shall follow the service and repair leakage recommendations (e.g., from manu facturer and in service shop manual), including any service procedures established to prevent refrigerant from entering the cabin or airflow

path. 7. High - side and low - side fittings shall be fitted with protective or sealing caps. 8. All MVAC system service fitt ings shall be located for ease of attachment of service hoses and shall be designed to minimize direct impingement of refrigerant on the service technician. Piping shall be of robust design to avoid damage or permanent deformation while connecting or disc onnecting the service hose coupling(s) from factory charging and service equipment. 9. HFO - 1234yf must be used with the following service fittings:  For the low - side service port, use quick - connect fittings with an outside diameter of 14 + 0.2 mm (0.551 + 0.00 787 inches).  For the high - side service port, use quick - connect fittings with an outside diameter of 17 + 0.2 mm (0.669 + 0 .00787 inches).  For connections with containers of 20 lbs or greater, use quick - connect fittings with an out side diameter of 14 + 0. 2 mm (0.551 + 0.00787 inches).  All fittings must be different from those for any other refrigerant. 10. A plainly legible and durable refrigerant label shall be mounted in a clearly visible location under hood that does not require the removal of any part s or covers to be read. The label shall: identify the refrigerant; state the amount of refrigerant charge in grams (or kilograms, to three decimal places); and identify the lubricant type (polyalkylene glycol [PAG] or polyolester [POE]). The label either shall include the chemical safety symbol for “flammable” or shall state in text that the refrigerant is flammable in letters at least 3 mm in height that are red in color. The label shall contain the name or logo of the original equipment vehicle manufac turer or the refrigeration system*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 133 of 134 manufacturer responsible for design compliance with this rule and with SAE standards. The label shall have a minimum size of 60 mm by 30 mm. It shall have text in bold - ty pe letters at least 3 mm in height for identifying refrigerant, lubricant type and refrigerant amount. If the label contains text only and no symbols, the label shall also state the following: “CAUTION SYSTEM CONTAINS REFRIGERANT R - 1234yf UNDER HIGH PRESSURE - TO BE SERVICED ONLY BY QUALIFIED PERSONNEL ” 1 1. Manufacturers must conduct Failure Mode and Effect Analysis (FMEA) as provided in SAE J1739 (adopted 2009). Manufacturers must keep the FMEA on file for at least three years from the date of creation. 3. Appendix B to Subpart G is amended b y revising the entry for ``CFC - 12 Motor Vehicle Air Conditioners (Retrofit and New Equipment/NIKs)'' in the table titled ``R efrigerants -- Unacceptable Substitutes'' to read as follows: Refrigerants -- Unacceptable Substitutes * * * * * End - use Substitute Decision Comments CFC - 12 Motor Vehicle Air Conditioners (Retrofit and New Equipme nt/NIKs) R - 405A....... Unacceptable. R - 405A contains R - c318, a PFC, which has an extremely high GWP and lifetime. Other Substitutes exist which do not contain PFCs. Hydrocarbon Blend B.... Unacceptable. Flammability is a serious concern. Data have not been submitted to demonstrate it can be used safel y in this end - use . Flammable Substitutes, other than R 152a or HFO 1234yf in new Unacceptable. The risks associated with using flammable substitutes (except R - 152a and HFO - 1234yf) in this end - use have not been*** E.O. 12866 Review _ Draft _ Do Not Cite, Quote, or Release During Review ***

Page 134 of 134 equipment. addressed b y 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. ] BILLING CODE 6560 - 50 - P