We recognize that more studies will be performed on HFO-1234yf, further addressing risk.  EPA's New Chemicals Program has recommended additional testing of acute exposure in rabbits, including pregnant rabbits (April 2, 2010; 75 FR 16706).  In addition, the manufacturer is voluntarily conducting a multi-generation reproductive study.  If these or other future studies call into question the basis for our decision today, section 612 allows citizens to petition EPA to change or modify a listing decision or EPA could determine on its own to reassess this decision.
      Comment:  In late comments, a commenter stated that EPA appears to be relying on a SNUR to reduce risks to human health from exposure to HFO-1234yf.  This commenter stated that EPA must re-open the comment period on the proposed SNAP rule so that commenters may reassess the extent to which the final restrictions of the SNUR will be effective at limiting adverse human health effects.  The same commenter noted that information on new price levels and availability is needed to assess the effectiveness of the SNUR.
      Response:  EPA's final SNUR addresses potential risks to human health from exposure to HFO-1234yf.  However, as discussed above in section V of the preamble, "Why is EPA listing HFO-1234yf as acceptable subject to use conditions?", this final SNAP rule does not allow for the use of HFO-1234yf with small cans or containers (i.e., container sizes that would be purchased by DIY users, such as small cans and containers less than 5 lbs) because it does not contain specifications for unique fittings for can taps and for these smaller containers.  Existing SNAP program regulations in appendix D to subpart G of 40 CFR part 82 require the use of unique fittings for specific purposes (e.g., high pressure-side service port, small can taps) for each MVAC refrigerant, as submitted by the refrigerant manufacturer.  Before HFO-1234yf can be introduced in small containers typically used by DIYers, the manufacturer must submit unique fittings to EPA, we must conclude that they are unique, and we must issue new proposed and final rules specifying those fittings.  In addition, the final SNUR would not allow distribution in commerce of products intended for use by a consumer for the purposes of servicing, maintenance and disposal involving HFO-1234yf until at least 90 days after submission of a SNUN.  These and other requirements ensure  -  to the extent possible, with the information currently available to EPA  -  that HFO-1234yf has no greater risk overall for human health and the environment than other available refrigerants for MVAC.
      Under the final SNUR, it is necessary for EPA to receive and complete its review of a significant new use notice (SNUN) with additional information on consumer exposure risks before  -  if the Agency so decides  -   HFO-1234yf may be manufactured, imported or processed for the purpose of use in DIY servicing, with or without other restrictions.  We would also consider information in the SNUN before issuing a final rule specifying unique fittings for use with small containers of refrigerant.
      In comments EPA received on the proposed SNAP rule, the initial direct final SNUR that was withdrawn and the proposed SNUR, no commenters suggested making the provisions of the SNUR stricter or suggested adding use conditions under the SNAP program for addressing risks to consumers during DIY servicing.  A number of commenters stated that no restrictions were needed to address risks to consumers during DIY servicing, while other commenters stated more broadly that EPA should find HFO-1234yf unacceptable because of its toxicity risks.  We provided an additional opportunity for comment on the SNAP rule after the direct final SNUR was issued (February 1, 2010; 75 FR 4083), in response to a request to reopen the public comment period (EPA-HQ-OAR-2008-0664-0077.1), in part to allow comment on the relationship between these two rulemakings that both address HFO-1234yf.  However, we do not believe that the conditions of the final SNUR are necessary to the determination that we are making here.  As noted above, this final rule does not allow for the servicing of HFO-1234yf from container sizes that would be purchased by DIY users because of the lack of an approved unique fitting for smaller containers.  Further rulemaking under SNAP will occur prior to such use and any risks can be addressed in that rulemaking package.  At that time, we will be able to fully consider the impact of the final SNUR.
      2.	Flammability
      Comment:  Five commenters stated that HFO-1234yf has a low likelihood of ignition, especially under the conditions encountered in an automotive application.  One commenter stated that the mere presence of high refrigerant concentrations does not contribute to a hazardous condition because an ignition source of sufficient energy must also be present.  Another commenter disagreed with EPA's view that a flammability risk exists.  Other commenters stated that additional review of the available information regarding flammability of HFO-1234yf needs to be conducted.  Some commenters stated that EPA should consider restricting concentrations of HFO-1234yf to much lower concentrations than to the lower flammability limit (LFL) of 6.2%.
      Response:  The available evidence indicates that HFO-1234yf will not present a significant risk of flammability and that any risk it poses is not greater than the risk presented by other available alternatives.  For example, because of its higher LFL, its considerably higher minimum ignition energy (5000 mJ to 10,000 mJ), and its slower flame speed (1.5 cm/s), HFO-1234yf is less flammable than HFC-152a, a substitute that EPA has already found acceptable subject to use conditions.
      Further, an analysis conducted for SAE International's Cooperative Research Program by Gradient Corporation (CRP, 2009) found that there was a very low flammability risk (on order of 10[-14] occurrences per operating hour or 1 occurrence in 100 years across the entire U.S. fleet of passenger vehicles).  This was due to the low probability of achieving a concentration of HFO-1234yf above the LFL at the same time as having a sufficiently high energy source to cause the refrigerant to ignite.  Further, even that low probability of ignition of HFO-1234yf may be overstated, because it assumes that a vehicle collision severe enough to crack open the evaporator (located under the windshield and steering wheel) is not severe enough to crack the windshield or windows that would hold refrigerant in the passenger compartment.  In a sensitivity analysis, the SAE CRP considered how the flammability risk would change if a refrigerant release into the passenger compartment only occurs in a collision causing damage to more than the MVAC system.  That analysis estimated that the risk of exposure to an open flame would then be reduced by a factor of 23,000, to approximately 4 x 10[-19] occurrences per vehicle operating hour (EPA-HQ-OAR-2008-0664-0056.2).
      For the reasons provided above in sections IV and VII.B of the preamble, "What are the final use conditions and why did EPA finalize these use conditions?" and "Use conditions," EPA does not believe it is necessary to establish a use condition limiting refrigerant concentrations, whether at 6.2% or some other, lower value.  We believe the final use conditions sufficiently address flammability risks.
      Comment:  Three commenters stated that HFO-1234yf is flammable and that the proposed regulation does not offer any restrictions to protect those persons handling HFO-1234yf, nor does it restrict its sale and use by the general public.
      Response:  The purpose of the use conditions is to ensure that HFO-1234yf will not pose a greater risk to human health or the environment than other available or potentially available substitutes.  For all of the reasons provided in sections IV and V above, EPA has determined that HFO-1234yf will not pose a greater risk than other substitutes for MVAC.  As explained above, EPA proposed restricting concentrations of the refrigerant below the LFL of 6.2% as a use condition.  Based on comments and additional analysis, EPA has concluded that it is not necessary to require use conditions limiting refrigerant concentrations to below the LFL; rather, the use conditions now specify design parameters for MVAC systems and require an FMEA.  This will ensure that systems are designed to minimize risk not only from flammability, but also from exposure to HF.
      We will address use by service personnel through a rulemaking under section 609 of the CAA.  Although these rules will further address issues of interest to service personnel and others that might handle HFO-1234yf used in MVAC systems, we note that our risk assessments of use of HFO-1234yf found that significant flammability risks do not exist for personnel installing the refrigerant at equipment manufacture, professional servicing personnel, and personnel working with automobiles at equipment end-of-life (EPA-HQ-OAR-2008-0664-0036 and -0038).  Moreover, we note that an industry-sponsored analysis of risks found the risk of ignition of HFO-1234yf to a technician is extremely small, on the order of 10[-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 use (typically 20 lbs or larger) and thus HFO-1234yf may not be used in small container sizes that would be the type purchased by the general public.  We will address the issue of risk to DIY users through a future rulemaking under SNAP if we receive a request for unique fittings for smaller containers from the refrigerant manufacturer.  We also are addressing risks to DIY users through the Significant New Use Rule under the Toxic Substances Control Act (October 27, 2010; 75 FR 65987).
      Comment:  One commenter stated that compared with HFC-134a, the explosion probability of HFO-1234yf is much higher based on testing done at the Federal Institute for Materials Research and Testing (Bundesanstalt für Materialforschung und  -  prüfung, BAM).  Other commenters disagreed with those flammability conclusions, finding the testing results to be expected but not representative of real-world use in MVAC.  These commenters stated that the flammability risks of HFO-1234yf were not significant and that the mixtures of HFO-1234yf and ethane used in the testing would not be seen in MVAC in actual operations.
      Response:  As explained above in section VII.B, we do not believe that these tests  are relevant for assessing the flammability risks of HFO-1234yf as used in MVAC systems because they evaluated flammability based on the presence of ethane, a substance that should not be present in any situation that might cause flammability risks for MVAC systems.
            3.	Toxicity of Hydrogen Fluoride (HF)
      Comment:  Two commenters stated that there is low risk due to exposure to HF.  One of these commenters stated that (1) for vehicles that do not discontinue the use of the blower after collision, the risk due to exposure to HF from use of HFO-1234yf is approximately twice the risk with the current use of HFC-134a, and (2) for vehicles that discontinue the use of the blower after collision, the risk due to exposure to HF when using HFO-1234yf is approximately the same as that with the current use of HFC-134a (on order of 10[-12] occurrences per operating hour, or one in one trillion).  The second commenter stated that there is no need for concentration limits to protect against exposure to HF because the risks from exposure to HF from HFO-1234yf are similar to what would be experienced with HFC-134a.  One commenter also stated that concentrations of HF as low as 0.3 ppm cause a sensation of irritation.  The commenter stated that this characteristic would deter someone from remaining exposed to excessive concentrations from an open hood.
      Other commenters stated that that there is a high probability of HF generation in cars from HFO-1234yf.  One commenter stated that the flammability of HFO-1234yf makes the production of HF more likely and increases the risk of HF exposure to vehicle passengers, to workers at chemical facilities, automotive manufacturing facilities, vehicle servicing facilities, and to the general public.  Two commenters stated that various health and safety concerns related to HF generation and its toxicity are well studied and documented, and three commenters stated that use of HFO-1234yf is unacceptable as there is increased potential for HF exposure and related casualties.
      Response:  EPA has considered the potential for generation of HF from HFO-1234yf, including the SAE CRP's evaluation of scenarios that might cause workplace and consumer exposure to HF (EPA-HQ-OAR-2008-0664-0056.2).  SAE CRP members conducted tests to measure HF concentrations and to identify factors that were most likely to lead to HF formation.  One set of tests conducted in a car found that HF measurements inside the passenger cabin were 35 ppm or less (EPA-HQ-OAR-2008-0664-0056.2).  This highest value occurred during release of the entire charge of refrigerant of 1000 g into the passenger cabin with ignition started by a butane lighter augmented with an additional spark -- a highly conservative scenario.  (A more typical charge would be 575 g, and it would be unlikely to have the amount of ignition energy that occurred artificially in the experiment with use of both a butane lighter and an additional spark source.)  A second set of tests focusing on HF in the engine compartment tried to simulate a major rupture in the AC system that would release 12 g/s of refrigerant across 5 cm onto an artificial hot surface at temperatures of 450 ºC (typical of the exhaust manifold) and 700 ºC (most extreme case), with the car hood in various positions.  This testing found HF concentrations as high as 120 ppm at the hot surface in the engine compartment in the worst case, with interior passenger cabin values of 40 to 80 ppm in the worst case (EPA-HQ-OAR-2008-0664-0056.2).  This test was conservative for the following reasons:  the temperature was high, representing extreme conditions; the refrigerant was released extremely close to the hot surface; the hood was closed; and the refrigerant ignited briefly.  The other test trials under less extreme conditions resulted in HF concentrations of a few ppm.  The test trials also found somewhat lower concentrations of HF generated during testing of HFC-134a using the same procedures and apparatus, with maximum concentration of 36 ppm in the engine compartment and concentrations of less than 8 ppm in the passenger compartment in the worst case.  The SAE CRP selected an Acute Exposure Guideline Limit (AEGL)-2 of 95 ppm over 10 minutes as its criterion for determining excessive risk.  This limit was developed to protect against irreversible health effects when exposure remains below the limit of 95 ppm over 10 minutes, but short-term discomfort or irritation could still occur.  Thus, even assuming a passenger inside a vehicle was exposed to HF at the highest level found in the test of 80 ppm, exposure at this level would at worst cause discomfort and irritation, rather than permanent or disabling health effects.
      For both HFO-1234yf and for HFC-134a, HF concentrations in the passenger compartment fell between the level that would protect against all adverse health effects (AEGL-1 of 1.0 ppm for 10 minutes to 8 hours) and the level that would protect against irreversible or disabling health effects (AEGL-2 of 95 ppm over 10 minutes) (NRC, 2004).  The SAE CRP concluded that the probability of such a worst case event is on the order of 10[-12] occurrences per operating hour (EPA-HQ-OAR-2008-0664-0056.2).  Commenters provided information indicating that this level of risk for HF generation is the same order of magnitude for both HFC-134a and for HFO-1234yf.  EPA considers the risk level presented by HFO-1234yf to be similar to that of the refrigerant currently being used by automobile manufacturers, HFC-134a.  Therefore, there is no reason to regulate HFO-1234yf more stringently to protect against HF exposure than for HFC-134a.
      Comment:  One commenter stated that testing with HFOs commissioned by the environmental organization Greenpeace in 2001 hinted at a multitude of decomposition products with high reactivity.  The commenter stated that apparently even lubricants (polyalkylene glycol--PAG) break down to HF when in contact with HFO-1234yf in a MVAC system.  The commenter further expressed that BAM testing showed that burning HFO-1234yf resulted in concentrations of HF greater than 90 ppm in the engine compartment.  The commenter concluded that the tests prove that in a standard system with standard charge (900 grams) and oil, the risk for humans would be incalculable.
      Response:  The commenter has not provided sufficient information on the testing commissioned by Greenpeace in 2001 for the Agency to determine what the results were or whether the testing conditions are relevant to this action.  Concerning the BAM testing, EPA has not seen a testing report or a detailed description of the experimental method that allows for a full evaluation.  Based on the information provided by the commenter, the temperature of the released substance reached 600 ⁰C and HF concentrations of over 90 ppm were measured in the engine compartment.  According to a risk assessment from an automobile manufacturer, such a high temperature is unlikely and could only be achieved on the exhaust manifold under heavy engine loads such as when a vehicle is climbing a hill, and the temperature of the exhaust manifold would drop in a minute or so during deceleration (EPA-HQ-OAR-2008-0664-0081.1).  It is not clear what the conditions were for the study mentioned by the commenter.  For example, it is not clear if the refrigerant was mixed with compressor oil as it normally would be in an MVAC; inclusion of oil with a relatively low flashpoint would be expected to lead to ignition at lower temperatures (EPA-HQ-OAR-2008-0664-0056.2, EPA-HQ-OAR-2008-0664-0118.1).  It also is not clear if the compressor fan was operating during the test.  During normal vehicle operation, the fan would cool down the compressor and the engine compartment, avoiding the temperature of 600 °C on hot surfaces in the engine.
      Other tests have found that HF concentrations in the engine compartment were approximately 5 ppm or less and only in the worst case (hot surface temperature of 700 ° C, closed hood on engine compartment) did HF concentrations attain a value of approximately 120 ppm in the engine compartment (OAR-2008-0664-0056.2).  This level is slightly higher than the AEGL-2 of 95 ppm on a 10-minute average and is lower than the AEGL-3 for HF of 170 ppm on a 10-minute average, the value that would protect against life-threatening exposure but would not necessarily prevent long-term health effects.  However, we note that we do not anticipate any circumstance where a person would be exposed to these levels in an engine compartment because such conditions would not occur during vehicle servicing, but rather during vehicle operation.  Further, in the case of a collision resulting in a fire, we would expect that professional first responders have training in chemical hazards and possess appropriate gear which would prevent them from receiving HF exposures above health-based limits (EPA-HQ-OAR-2008-0664-0056.2) and an interested by-stander would quickly back away from a fire or from irritating HF vapors, thus preventing excessive HF exposure.  The concentration measured in the passenger compartment in the same worst-case situation was in the range of 40 to 80 ppm, less than the concentration in the engine compartment and less than the AEGL-2 intended to protect against long-term health effects.  Thus, we disagree with the commenter's assertion that HF exposures from thermal decomposition or combustion of refrigerant would be likely to results in fatalities.  We further note that the HF concentrations found in the passenger compartment were lower than the health-based limit, the AEGL-2 of 95 ppm over 10 minutes.
      We also note that the risks presented by HFO-1234yf are not significantly different than the risk posed by HFC-134a, the refrigerant currently in use in MVAC systems.  Mixtures of HFC-134a and compressor oil also combust and generate HF.  Testing performed using HFC-134a under worst-case conditions in the engine compartment (hot surface temperature of 700 ºC, closed hood on engine compartment) found HF concentrations as high as 36 ppm in the engine compartment and 2 to 8 ppm in the passenger compartment.  The amount of HF generated from a typical charge of HFC-134a, if it all burned or decomposed, could be even more than for the expected charge of HFO-1234yf because charge sizes using HFO-1234yf are expected to be smaller (EPA-HQ-OAR-2008-0664-0056.2).  The SAE CRP considered potential risks of HF exposure from both HFO-1234yf and from HFC-134a.  Both presented potential risks on the order of 10-12 occurrences per operating hour (EPA-HQ-OAR-2008-0664-0056.2, -0096.1).  This corresponds to less than one case per year across the entire fleet of motor vehicles in the U.S.  Although there is no specific testing data on HF production from HFC-152a, another acceptable refrigerant for MVAC, since this compound contains fluorine, it presents risks of HF generation as well.  As discussed above in Section IV of the preamble, we are not requiring specific use conditions that regulate production of HF, either directly or indirectly, because of the low level of risk.  However, the final use conditions in this rule address the risks of HF production, as well as risks of flammability, by requiring certain design safety features of MVAC systems using HFO-1234yf and by requiring risk analysis for each car model through FMEAs.
      Comment:  A commenter provided results from a test by IBExU on the decomposition of HFO-1234yf under heat (EPA-HQ-OAR-2008-0664-0053.3).  This commenter strongly warned against a decision in favor of HFO-1234yf because it would form highly toxic HF when burning.  Three commenters disagreed that the results of the IBExU testing were relevant because test conditions did not represent realistic conditions.  One commenter said that the SAE risk assessment, which used actual vehicle test data for HF formation, found that actual HF formation rates are far below the levels [from the IBExU test results] cited by the first commenter, the Federal Environmental Agency (Umweltbundesamt -- UBA).
      Response:  The IBExU testing of HF generation from HFO-1234yf is not relevant to assessing the risks of HFO-1234yf as a refrigerant in MVAC.  Laboratory tests concerning the nature of HF generation on hot surfaces found that this depends on the contact time of reactants on the hot surface, the temperature of the hot surface and the movement of refrigerant in diluted concentrations due to airflow (EPA-HQ-OAR-2008-0664-0056.2; EPA-HQ-OAR-2008-0664-0116.2).  The IBExU testing involved heating the refrigerant steadily in a sealed flask.  Thus, the contact time in that test was far greater than would occur in an engine compartment and the movement of refrigerant in that test was essentially zero, unlike in an engine compartment where there would be constant air movement.
      Comment:  Another test from BAM reported by UBA examined HF formation from HFO-1234yf and from HFC-134a (EPA-HQ-OAR-2008-0664-0080.1).  Fifty grams of refrigerant was streamed through a hole of 2 mm diameter onto a hot metal surface.  The study found that pure HFO-1234yf exploded on the hot surface whereas pure HFC-134a did not.  The study also found that when HFO-1234yf was mixed with 3% oil, it exploded at 600 °C.  The commenter stated that handling of HFO-1234yf in the presence of hot metal surfaces results in HF formation in concentrations far above allowed workplace concentrations.
      Response:  These results are not consistent with results from hot-plate tests conducted by an automobile manufacturer and by a chemical manufacturer for the SAE CRP (EPA-HQ-OAR-2008-0664-0056.2; EPA-HQ-OAR-2008-0664-0115.1).  Those manufacturers found that neither HFO-1234yf nor HFC-134a alone ignited at 900 °C.  One of these tests found that HFO-1234yf mixed with PAG oil combusted starting at 730 °C, while HFC-134a mixed with PAG oil ignited at 800°C and above; the other test observed no ignition of a blend of each refrigerant with PAG oil at 800 °C, but both blends ignited at 900 °C.  Based on the lack of reproducibility of the specific ignition temperature, it appears that the specific ignition temperature may depend on variables in the testing (e.g., flash point of the oil used, amount of mixture used, angle of application, and air flow available).  This information also shows that mixtures of refrigerant with compressor oil can combust at lower temperatures than pure refrigerant and that mixtures of HFO-1234yf and oil and mixtures of HFC-134a and oil present similar risks of ignition and HF generation.  Thus, we concluded that the risks of toxicity from HF exposure due to combustion or decomposition of HFO-1234yf are comparable to those from HFC-134a.
      Further, the risks from toxicity of HF posed by both refrigerants are small.  The SAE CRP estimates this risk on the order of 10-12 cases per operating hour (EPA-HQ-OAR-2008-0664-0086.1).  This is equivalent to less than one event per year across the entire fleet of motor vehicles in the U.S.  For comparison, this is less than one ten-thousandth the risk of a highway vehicle fire and one fortieth or less of the risk of a fatality from deployment of an airbag during a vehicle collision (EPA-HQ-OAR-2008-0664-0056.2).
      E. Retrofit usage
      Comment:  Several commenters stated that HFO-1234yf should be allowed initially in new vehicles but should not be used to retrofit vehicles using HFC-134a, or at least not unless there are industry standards to guide such a process.  Other commenters stated that it is critical to allow a natural phase-out of the fleet of cars using HFC-134a as the refrigerant, rather than requiring retrofitting existing cars with HFO-1234yf.  A commenter expressed concern that retrofitting of HFC-134a MVAC systems with HFO-1234yf would result in cases of cross-contamination of refrigerant, while another commenter contested this statement and found it unsupported.  Other commenters opposed obstacles that would prevent older MVACs from being retrofitted to the new refrigerant.  These commenters mentioned the potential for greenhouse gas benefits when retrofitting systems currently using HFC-134a with HFO-1234yf.
      Response:  The submitter did not request review of HFO-1234yf for retrofitting vehicles and thus EPA did not review HFO-1234yf as acceptable (or acceptable subject to use conditions) for retrofitting in MVAC in this rulemaking.  Consistent with the request submitted to the Agency, we proposed to find HFO-1234yf acceptable for use subject to use conditions in new MVAC systems and evaluated its risks only for use in new systems.  We will consider the retrofit use of HFO-1234yf in MVAC systems if we receive a submission that specifically addresses retrofitting and the risks that are unique to retrofitting.  In response to the commenter who raised a concern about a "phase-out" of HFC-134a and the potential that we would "require" use of HFO-1234yf, we note that our rulemakings under SNAP do not require use of any specific substitute.  Rather, under SNAP, we have established lists of substitutes that are acceptable for use in various end-uses (such as for MVACs) and end-users are free to choose which substitute to use, but must do so consistent with any use conditions that apply.  As stated in the rule establishing the SNAP program, "The Agency...does not want to intercede in the market's choice of available substitutes, unless a substitute has been proposed or is being used that is clearly more harmful to human health and the environment than other alternatives."  59 FR 13046, March 18, 1994.  We further note that this rulemaking does not change the status of HFC-134a, which remains an acceptable substitute for use in MVACs, subject to use conditions.
      F. Use by "do-it-yourselfers"
      Comment:  Some commenters raised concerns about EPA's statements in the proposed rule about potential health effects that might occur without professional training and the use of CAA Section 609 certified equipment.  These commenters stated that the studies and testing in the docket support a finding that use of HFO-1234yf by non-professionals is safe and do not offer valid technical support for EPA's concerns.
      Response:  EPA's risk assessment and risk screen both indicated that worst-case exposure levels expected during servicing by do-it-yourselfers are of potential concern (EPA-HQ-OAR-2008-0664-0036 and EPA-HQ-OAR-2008-0664-0038).  In both documents, this was based upon estimated exposure levels from a 2008 risk assessment by Gradient Corporation for the SAE CRP (EPA-HQ-OAR-2008-0664-0008).  In EPA's risk assessment (EPA-HQ-OAR-2008-0664-0036), we found that the level that EPA determined did not cause health effects in laboratory animals might be only 2 to 3 times higher than the exposure predicted for that use (the "margin of exposure").  Our risk assessment indicated a higher, more protective margin of exposure of at least 30 was needed to account for uncertainty in the extrapolation from animals to humans and for variability in the human population.  In other words, we found that based on worst-case assumptions, a do-it-yourselfer's exposure could be 10 or more times the level that EPA considered safe.  The margin of exposure was calculated using a conservative estimated exposure level of 45,000 ppm over 30 minutes and a human equivalent concentration of 98,211 ppm from a no-observed adverse effect level that we selected as the point of departure for risk assessment (EPA-HQ-OAR-2008-0664-0036).
      However, under this final rule, unique fittings have only been submitted for servicing fittings for the high-side and low-side ports and for large containers of HFO-1234yf and thus the acceptability listing is limited to use of HFO-1234yf with the unique fittings specified (e.g., for large containers of 20 pounds or more).  We expect these containers would not be purchased by DIYers because of their expense ($800 or more per container) and because they would contain enough refrigerant for 10 charges or more.  We will continue to review the issue of safe use for DIYers if and when we are requested to review unique fittings for a smaller container size.  In addition, EPA is further addressing the issue of risks to DIYers in the Significant New Use Rule for 1-propene-2,3,3,3-tetrafluoro- (75 FR 65987, October 27, 2010).  This SNUR requires submission of a SNUN at least 90 days before sale or distribution of products intended for use by a consumer for the purpose of servicing, maintenance and disposal involving HFO-1234yf.
      EPA's proposed rule on the use of HFO-1234yf as a substitute for CFC-12 in new MVAC systems did not propose to establish use conditions for servicing vehicles by certified professionals, but our analyses indicate that there is not significant risk to certified professionals, because HFC-134a, which is currently used in most MVAC systems, presents similar risks and professionals have the knowledge and equipment to mitigate any risks.  We plan to further address servicing by professionals when we develop a new rule under section 609 of the Clean Air Act for servicing and maintenance of MVAC systems.
      Comment:  Some commenters supported prohibiting sale of HFO-1234yf in small containers.  Other commenters stated that only certified technicians should be allowed to purchase and use refrigerants, including HFC-134a and HFO-1234yf.  Other commenters found no data to support restrictions on the sale of HFO-1234yf to non-professionals.
      Response:  As noted previously, the submission only addressed unique fittings for large containers (e.g., 20 lbs or larger) of HFO-1234yf.  If anyone is interested in using HFO-1234yf in small cans or other small containers, they would need to contact the refrigerant manufacturer to submit unique fittings for approval under the SNAP program.  Thus, under this final rule, we believe that only certified technicians will purchase HFO-1234yf because the larger containers are likely to be prohibitively expensive for individuals performing DIY servicing ($800 or more for a 20 lb cylinder) and are likely to be too large for most individuals to use, containing enough refrigerant for 10 or more charges.
      We also note that in a separate final rule under the authority of TSCA (October 27, 2010; 75 FR 65987), EPA requires among other things, that notice must be given to EPA 90 days before (1) HFO-1234yf is used commercially other than in new passenger cars and vehicles in which the charging of motor vehicle air conditioning systems with HFO-1234yf was done by the motor vehicle OEM or (2) sale or distribution of products intended for use by a consumer for the purpose of servicing, maintenance and disposal involving HFO-1234yf.
      Comment:  A commenter stated that banning DIY use of HFO-1234yf will mean that car owners will be forced to have professionals perform service work on their AC systems at a significantly higher cost.  This commenter stated that millions of lower-income motorists may be forced to go without air conditioning each year or may seek out lower-cost alternatives such as propane or HFC-152a.
      Response:  While this final rule effectively prohibits DIY use because the final use conditions do not include unique fittings allowing for use with small refrigerant containers, we are not making any final determination about whether HFO-1234yf may be safely used by DIYers.  As we noted above, we have not yet received a submission for DIY use or received unique fittings for small containers from the manufacturer, but would evaluate such submissions when we receive one.  We note that because it is unlikely that any cars will have MVAC systems with HFO-1234yf before the 2013 model year, we believe the availability of small containers for DIY use will not be of concern until such cars are sold and there is a need to recharge a new MVAC system on a model year 2013 vehicle.  The separate final Significant New Use Rule that the Agency has issued under TSCA (75 FR 65987; October 27, 2010) requires submission of a Significant New Use Notice at least 90 days before sale or distribution of products intended for DIY use.
      With respect to the commenter who suggests that some people may seek lower cost alternatives, presumably to repair an existing MVAC, we note that under current EPA regulations in appendix D to subpart G of 40 CFR part 82, it is not legal to top-off the refrigerant in an MVAC system with a different substitute refrigerant.
      G.	Servicing issues

      Comment:  Several commenters stated that appropriate training and certification should be required to purchase HFO-1234yf for use in MVACs.  Four commenters also stated that the final regulation should include a provision requiring proof of certification in order to purchase HFO-1234yf, and recommended that current AC systems tests (i.e., for CAA section 609 certification) be updated.
      Some commenters disagreed with EPA's statement that HFO-1234yf may cause serious health effects when used in servicing and maintaining MVACs without professional training.  Another commenter stated that EPA is limiting productivity by only allowing dealerships to perform refrigerant maintenance, and that independent MVAC service shops should be allowed to be certified.  The commenter also questioned who will monitor "certified" technicians employed by dealerships that may do work on the side.  A commenter representing automobile dealerships specifically opposed mandatory requirements for certification of technicians because of potential costs and burden on small businesses.
      Response:  As background for the public comments, we note that under EPA's regulations implementing section 609, one must be a section 609 certified technician in order to purchase CFC-12 or other ODS for use in MVAC (40 CFR 82.34(b)).  Section 609(e) of the CAA itself specifically prohibits sale of small containers less than 20 pounds with Class I or Class II substances suitable for use as a refrigerant in MVAC, except for individuals performing service for consideration in compliance with section 609.  However, there is no comparable restriction on the sale of HFC-134a or on other substitutes for MVAC that do not contain Class I or Class II ODS, such as HFO-1234yf.
      In the NPRM (74 FR 53449), EPA stated that any specific training and certification requirements would be adopted through a rulemaking under the authority of CAA section 609 and would be codified in subpart B of 40 CFR part 82, which contains the regulations implementing section 609.  We will address concerns regarding certification and training requirements during that separate rulemaking process.  We note, however, that the CAA itself mandates that persons performing service for consideration that involve the refrigerant must be properly trained and certified.  Furthermore, as noted previously, we believe that there is not a significant health risk to professionals from HFO-1234yf because they will have the knowledge and equipment to mitigate any risks.  Also, because HFC-134a presents similar risks to HFO-1234yf, and the flammability risks of HFO-1234yf are less than those for HFC-152a, the health risks of HFO-1234yf are not significantly greater than those of other available substitutes.
      With regard to whether independent service shops could service MVACs with HFO-1234yf or whether service would be limited to "dealerships," we note that neither this rule nor any other CAA regulation would limit servicing to dealerships.  The comment may concern the withdrawn SNUR, 75 FR 4983 (February 1, 2010), which referred to the "original equipment manufacturer"; the commenter may have interpreted this term to mean an automobile dealership.  The final SNUR (October 27, 2010; 75 FR 65987) requires a significant new use notice to EPA at least 90 days before "commercial use other than in new passenger cars and vehicles in which the charging of motor vehicle air conditioning systems with the PMN substance [HFO-1234yf] was done by the motor vehicle original equipment manufacturer."  This requirement restricts commercial use of HFO-1234yf to use for vehicles that were initially charged with HFO-1234yf by the automobile's manufacturer, as opposed to allowing commercial use of HFO-1234yf for vehicles initially charged with a different refrigerant.  The term "original equipment manufacturer" refers to the automobile manufacturer, not to dealerships.
      Comment:  Commenters indicated that SAE International is developing standards for safety and servicing of alternative refrigerant HFO-1234yf MVAC systems.  Another commenter stated that there are appropriate mechanisms within the industry for training.  One commenter representing automobile dealerships objected to mandatory Section 609 technician certification and training for use of HFO-1234yf, stating that because dealerships already train technicians on flammable substances in accordance with hazard communication standards of the Occupational Safety and Health Administration (OSHA), and since the risks associated with HFO-1234yf are similar to those that already exist in MVAC service facilities, mandatory training and proof of training is not necessary.  To enable training pursuant to the OSHA hazard communication standard, the commenter stated that MVAC system and refrigerant suppliers should provide dealerships with sufficient information on the hazards posed by HFO-1234yf.
      Response:  EPA is issuing use conditions in this final rule that reference relevant SAE technical standards on safety.  This rule does not, however, include a use condition  requiring technician training and does not refer to specific training standards.  We agree with the commenter that current technician training generally should be sufficient to ensure that professional technicians will use HFO-1234yf safely.  Although this SNAP determination does not contain a use condition regarding technician training, as noted above, section 609 of the CAA requires technician training for persons servicing for consideration.  EPA will consider in a separate rulemaking under section 609, whether it is necessary to modify our existing regulations under section 609 to include additional specifications for HFO-1234yf.
      Comment:  A commenter representing automobile dealerships opposed mandatory requirements for recycling and containment of the refrigerant because of potential costs and minimal environmental benefits.
      Response:  This rulemaking does not impose requirements for recycling or containment of the refrigerant.  A separate rulemaking under CAA section 609 will address practices required in the servicing of MVAC systems using HFO-1234yf, including recycling and recovery.  Further, EPA notes that Section 608 of the CAA prohibits the intentional release of any refrigerant during the maintenance, repair, service, or disposal of refrigeration and air conditioning equipment, unless the Administrator determines through rulemaking that such release does not pose a threat to the environment.  We have not made such a determination for HFO-1234yf.
      H.	Cost, availability, and small business impacts
      Comment:  One late commenter stated that there was insufficient information in the record on the cost, terms of availability and anticipated market share of HFO-1234yf for EPA to make the required statutory findings that HFO-1234yf "reduces the overall risk to human health and the environment" by comparison to other alternatives that are already available.  The commenter stated that this information is necessary in order for EPA to assess anticipated environmental effects adequately.  The same commenter stated that EPA's environmental analysis is based on price assumptions that were not disclosed and are no longer valid, and thus, EPA should subpoena the information from the manufacturer and reopen the public comment period.
      Response:  EPA believes that there was sufficient information in the record at the time of proposal for us to complete a meaningful environmental analysis, even in the absence of definitive cost information.  At the time of proposal, we had available both estimates from a trade magazine provided by the manufacturer (Weissler, 2008), as well as estimates of price provided in the initial submission from the manufacturer (EPA-HQ-OAR-2008-0664-0013).  The estimates of price provided by the manufacturer were claimed as confidential business information and thus were not available in the record to the public.
      We typically use this type of information for purposes of determining market penetration for a particular substance, so that we can evaluate how much of the substitute will likely be used and thus the environmental risks it might pose.  In this case, however, because the automobile industry tends to prefer use of a single substitute, information on the cost of the substitute was not critical to our analysis.  Thus, in conducting our environmental analysis, we took a conservative approach, assuming that all new MVAC systems began using HFO-1234yf by 2020 (i.e., full market penetration).  We also considered an even more conservative scenario, in which HFO-1234yf would be the only refrigerant used for stationary air conditioning and for refrigeration as of 2020, as well as for MVAC.  Even with these highly conservative assumptions, we found that there would not be sufficient negative environmental impacts due to emissions of HFO-1234yf to warrant finding it unacceptable.
      In the proposal, we mentioned a cost estimate for HFO-1234yf of $40-$60/lb (Weissler, 2008).  More recently, the first automobile manufacturer announcing its intention to use HFO-1234yf confirmed that this range does not underestimate prices of HFO-1234yf and is consistent with the manufacturer's long-term purchase contracts (Sciance, 2010).  Thus, the most recent information shows costs to be similar to those we considered at the time of proposal.  This data contradicts the late commenter's assertion that the manufacturer's effective monopoly would result in significantly different, higher costs that would invalidate EPA's earlier analysis.  In any event, assuming that costs were higher as suggested by the commenter, then we expect that use of HFO-1234yf would be less than assumed for our health and environmental risk analysis.  As mentioned in the proposal, emissions, and thus the resulting environmental effects such as impacts on local air quality or on production of TFA, would be expected to be less under a scenario with higher prices and less use of HFO-1234yf.  Our analysis assumes widespread use and thus its results would be protective.
      We note that where a new chemical is introduced, there is some uncertainty in the price.  At best, the manufacturer can provide rough estimates of price and of market share before the chemical is produced in commercial quantities and becomes subject to supply and demand pressures.  EPA's requirement for information on cost, anticipated availability in the market, and anticipated market share (40 CFR 82.178(a)(14) through (16)) should not be construed as requiring precise, detailed cost estimates based upon a well-defined methodology.  As noted above, we use these numbers for the purposes of predicting market penetration and thus how much of a particular substitute might be used and thus pose an environmental risk.  As we did for HFO-1234yf, we typically take a environmentally-protective approach to our evaluation, assuming use at least as high as that the cost and availability information may indicate.
      Comment:  A late commenter stated that the information in the record is insufficient for EPA to make a statutory finding that HFO-1234yf is "currently or potentially available."  The commenter stated that a previous decision by the United States Court of Appeals for the District of Columbia Circuit (Honeywell International, Inc. V. EPA, 374 F.3d 1363 (D.C. Cir. 2004)) implied that an interpretation of the term "available" in CAA section 612(c)(2) could potentially consider economic factors if EPA adopted such an approach as a reasonable interpretation of the statutory language.  The commenter states that EPA should obtain information as to the anticipated cost of HFO-1234yf if the manufacturer does not grant licenses to produce.
      Response:  The CAA does not require that EPA find a substitute to be available or potentially available when finding it acceptable.  Section 612(c) states:
      ...It shall be unlawful to replace any class I or class II substance with any substitute substance which the Administrator determines may present adverse effects to human health or the environment, where the Administrator has identified an alternative to such replacement that --
                        (1)  reduces the overall risk to human health and the environment; and
                        (2)  is currently or potentially available....
(emphasis added.)
      This section makes clear that it is not the substitute under review that must be available or potentially available, but rather alternative replacements for ODS that EPA determines pose less overall risk to human health and the environment than the substitute being reviewed.  Thus, if there are alternatives to the substance under review that are currently or potentially available and that pose less risk, EPA cannot find the substitute under review acceptable.  Section 612(c) establishes no requirement that EPA must determine that the substitute under review is "available."  See also 40 CFR 82.180(b)(describing types of listing decisions EPA can make in reviewing substitutes).
      We note that even if EPA was required to determine that the substitute under review is available or potentially available before it could make an acceptability determination, we believe that the available information supports that HFO-1234yf is potentially available.  EPA's definition of "potentially available" at 40 CFR 82.172 provides:

      Potentially available is defined as any alternative for which adequate health, safety, and environmental data, as required for the SNAP notification process, exist to make a determination of acceptability, and which the Agency reasonably believes to be technically feasible, even if not all testing has yet been completed and the alternative is not yet produced or sold.

This definition makes explicit that it is not necessary to have perfect information on a substitute nor is it necessary for the substitute to be produced or sold in order for EPA to consider it "potentially available."  Instead, it is necessary for EPA to find the health, safety and environmental data adequate to make a determination of acceptability, and for the Agency to reasonably believe that the alternative is "technically feasible," in order for the alternative to be potentially available.  We believe the record contains adequate information showing that HFO-1234yf is potentially available.  The manufacturer has submitted the information required under 40 CFR 82.178 (e.g., pre-manufacture notice form and TSCA/SNAP addendum form containing:  name and description of the substitute, physical and chemical information, information on ODP and global warming impacts, toxicity data, data on environmental fate and transport, flammability, exposure, cost and estimated production).  The submitter has also provided unique fittings as required under appendix D to subpart G of 40 CFR part 82.  Thus, we believe that there is "adequate health, safety, and environmental data."  Even if the commenter were correct about claims that higher costs would result if the manufacturer does not grant licenses for production, as discussed above, this does not affect the adequacy of the health, safety, and environmental data for HFO-1234yf, because we have protectively assumed widespread use that would result in more emissions and greater environmental impacts.  In addition, based on the experimental work conducted by the automobile industry, we reasonably believe that HFO-1234yf is technically feasible as a refrigerant.  Thus, HFO-1234yf would still be "potentially available" under the SNAP program's definition.
      One commenter points to Honeywell International, Inc. v. EPA, 374 F.3d 1363 in urging EPA to explicitly include cost as a consideration in determining whether a substitute is "potentially available."  In that case, the court vacated and remanded a SNAP decision in which EPA listed a foam blowing substitute as acceptable subject to "narrowed use limits" on the basis that for some niche foam blowing uses, the substitutes that were already listed as acceptable might not be available.  Under the narrowed use limits, the end-user would need to demonstrate and document that other substitutes were not technically feasible for a particular use.  The court vacated and remanded EPA's rule on the basis that EPA had considered cost in concluding that already listed substitutes might not be available based on "technical" feasibility, and that EPA had not attempted to justify the rule on the ground that the statute allows it to consider economic factors in making its SNAP determinations.  The court left open the question of whether EPA could attempt to interpret the term "available" in section 612(c) as allowing for consideration of costs.
      Again, we note that "available or potentially available" applies only to the substitutes against which the substitute at issue is being compared.  The Agency has not decided whether consideration of the cost of other substitutes should be a factor to consider in determining whether they are available or potentially available and thus should (or should not) be used for comparison to a substitute under review.  However, we note that for purposes of the substitute under review, the Agency firmly believes that cost should not be the primary or sole basis for finding a substitute unacceptable.  EPA's role is to determine the health and environmental risk associated with the use of substitutes and the market should serve to address the issue of costs.  Costs will necessarily be a factor considered by the automobile manufacturers in deciding which substitute to use.
      Comment:  Two commenters stated that EPA needed to perform further analysis on the potential small business impacts and costs of EPA's regulations and the introduction of HFO-1234yf.  A commenter representing recyclers of automobiles and scrap metal expressed concern about the regulatory burden and costs that automotive recyclers are likely to incur if they must manage flammable refrigerants that are regulated as hazardous waste under EPA's regulations implementing the Resource Conservation and Recovery Act (RCRA).  The same commenter also suggests that the RCRA subtitle C regulations would need to be changed to alleviate the hazardous-waste management requirements for handling HFO-1234yf.  The other commenter mentioned the costs to service and repair shops, end-of-life vehicle recyclers, and automobile dealerships, and stated that EPA needed to analyze costs to these small businesses under the Regulatory Flexibility Act (RFA).  This latter commenter stated that EPA should determine if a significant change in price and supply expectations would affect the way that these businesses handle and deal with automobile repairs and recycling.
      Response:  The RFA applies only when there are small entities subject to the requirements of the proposed or final rule.  5 U.S.C. § 604(a)(3).  We believe the potential burden of complying with RCRA regulations placed on those recycling or recovering a substitute is generally not pertinent to a decision of whether HFO-1234yf should be found acceptable under SNAP.  To the extent the commenters are suggesting that we must evaluate such costs for purposes of the Regulatory Flexibility Act, we note that under the RFA we evaluate costs imposed by the enforceable regulations being promulgated.  To the extent the costs referred to by the commenter are already imposed under RCRA, they would not be new costs, but costs associated with the relevant RCRA regulations.  Moreover, under this SNAP final rule, EPA is not requiring the use of HFO-1234yf, and thus the costs associated with its use are not due to enforceable regulatory requirements under SNAP.  To the extent there are enforceable requirements for those persons who choose to use this new substitute, those requirements (the "use conditions") apply primarily to manufacturers of automobiles and MVAC systems, because they concern design of MVAC systems.  The one use condition of the rule that applies to servicing of MVAC systems, and thus, could apply to small businesses, is the requirement for specific unique service fittings.  However, EPA's existing SNAP regulations at appendix D to subpart G of 40 CFR part 82 already require unique service fittings as specified by the refrigerant manufacturer.  Thus, the costs of purchasing new unique fittings for this refrigerant are imposed by the pre-existing regulation.  This rule specifies the requirements for the type of unique fitting, in accordance with the fittings provided to EPA by the manufacturer.  These fittings are part of the SAE J639 standard.  It is not clear that there would be any cost differential between these specific unique fittings and others that the automotive industry could adopt instead.  For these reasons, EPA is able to certify that this regulation will not create a significant impact on a significant number of small entities.
      Regulations concerning disposal of refrigerant from MVAC systems and other refrigerant-containing appliances under section 608 of the CAA are at subpart F of 40 CFR part 82.  Cost and benefit estimates for these regulations are at www.regulations.gov, docket EPA-HQ-OAR-2003-0167.  EPA notes that there may be costs of servicing or of disposal (end-of-life) to small businesses under future regulations under section 609 or 608 of the CAA.  We will conduct an analysis of such costs, and any potential significant impacts on small entities, as necessary, as part of those future rulemakings.
      Comment:  A commenter stated that to comply with requirements of the Unfunded Mandates Reform Act (UMRA), EPA needed to perform further analysis on the potential costs of EPA's SNAP regulations for HFO-1234yf to determine if the rule would result in the expenditure of $100 million or more per year by the private sector.  In particular, the commenter stated that EPA must obtain more information on pricing and the effect of the manufacturer's patent to analyze this.
      Response:  UMRA applies only to "enforceable duties" imposed on State, local, and tribal governments or on the private sector.  The SNAP rule does not impose duties on governments.  As we have noted previously, the SNAP program does not mandate the use of any specific substitute for ozone depleting substances.  Rather, through this action, we are expanding the choices of MVAC refrigerants available to the private sector.  The issue raised by the commenter concerning the cost of the refrigerant and the effect of the manufacturer's patent on pricing is not related to any requirement of the rule, and thus, EPA is not required to consider that cost under UMRA.
VIII.	How does the SNAP program work?
 	A. 	What are the statutory requirements and authority for the SNAP program?
Section 612 of the Clean Air Act (CAA) requires EPA to develop a program for evaluating alternatives to ozone-depleting substances (ODS).  EPA refers to this program as the Significant New Alternatives Policy (SNAP) program.  The major provisions of section 612 are:
              1. Rulemaking
Section 612(c) requires EPA to promulgate rules making it unlawful to replace any class I (i.e., chlorofluorocarbon, halon, carbon tetrachloride, methyl chloroform, methyl bromide, and hydrobromofluorocarbon) or class II (i.e., hydrochlorofluorocarbon) substance with any substitute that the Administrator determines may present adverse effects to human health or the environment where the Administrator has identified an alternative that (1) reduces the overall risk to human health and the environment, and (2) is currently or potentially available.
              2. Listing of Unacceptable/Acceptable Substitutes
Section 612(c) requires EPA to publish a list of the substitutes unacceptable for specific uses and to publish a corresponding list of acceptable alternatives for specific uses.  The list of acceptable substitutes is found at http://www.epa.gov/ozone/snap/lists/index.html and the lists of "unacceptable", "acceptable subject to use conditions", and "acceptable subject to narrowed use limits" substitutes are found at subpart G of 40 CFR part 82.
              3. Petition Process
Section 612(d) grants the right to any person to petition EPA to add a substance to, or delete a substance from, the lists published in accordance with section 612(c).  The Agency has 90 days to grant or deny a petition.  Where the Agency grants the petition, EPA must publish the revised lists within an additional six months.
              4. 90-day Notification
Section 612(e) directs EPA to require any person who produces a chemical substitute for a class I substance to notify the Agency not less than 90 days before new or existing chemicals are introduced into interstate commerce for significant new uses as substitutes for a class I substance.  The producer must also provide the Agency with the producer's unpublished health and safety studies on such substitutes.
              5. Outreach
Section 612(b)(1) states that the Administrator shall seek to maximize the use of federal research facilities and resources to assist users of class I and II substances in identifying and developing alternatives to the use of such substances in key commercial applications.
              6. Clearinghouse
       Section 612(b)(4) requires the Agency to set up a public clearinghouse of alternative chemicals, product substitutes, and alternative manufacturing processes that are available for products and manufacturing processes which use class I and II substances.
       B. 	What are EPA's regulations implementing section 612?
On March 18, 1994, EPA published the original rulemaking (59 FR 13044) which established the process for administering the SNAP program and issued EPA's first lists identifying acceptable and unacceptable substitutes in the major industrial use sectors (subpart G of 40 CFR part 82).  These sectors include:  refrigeration and air conditioning; foam blowing; cleaning solvents; fire suppression and explosion protection; sterilants; aerosols; adhesives, coatings and inks; and tobacco expansion.  These sectors compose the principal industrial sectors that historically consumed the largest volumes of ODS.
      	Section 612 of the CAA requires EPA to list as acceptable only those substitutes that do not present a significantly greater risk to human health and the environment as compared with other substitutes that are currently or potentially available.

       C.  	How do the regulations for the SNAP program work?
       Under the SNAP regulations, anyone who plans to market or produce a substitute to replace a class I or II ODS in one of the eight major industrial use sectors must provide notice to the Agency, including health and safety information on the substitute at least 90 days before introducing it into interstate commerce for significant new use as an alternative.  This requirement applies to the person planning to introduce the substitute into interstate commerce, typically chemical manufacturers, but may also include importers, formulators, equipment manufacturers, or end-users when they are responsible for introducing a substitute into commerce.
       	The Agency has identified four possible decision categories for substitutes: acceptable; acceptable subject to use conditions; acceptable subject to narrowed use limits; and unacceptable.  Use conditions and narrowed use limits are both considered "use restrictions" and are explained below.  Substitutes that are deemed acceptable with no use restrictions (no use conditions or narrowed use limits) can be used for all applications within the relevant end-uses within the sector.  Substitutes that are acceptable subject to use restrictions may be used only in accordance with those restrictions.  It is illegal to replace an ODS with a substitute listed as unacceptable, unless certain exceptions (e.g., test marketing, research and development) provided by the regulation are met.
       	After reviewing a substitute, the Agency may determine that a substitute is acceptable only if certain conditions in the way that the substitute is used are met to minimize risks to human health and the environment.  EPA describes such substitutes as "acceptable subject to use conditions."  Entities that use these substitutes without meeting the associated use conditions are in violation of section 612 of the Clean Air Act and EPA's SNAP regulations.
       	For some substitutes, the Agency may permit a narrowed range of use within an end-use or sector.  For example, the Agency may limit the use of a substitute to certain end-uses or specific applications within an industry sector.  The Agency requires a user of a narrowed use substitute to demonstrate that no other acceptable substitutes are available for their specific application by conducting comprehensive studies.  EPA describes these substitutes as "acceptable subject to narrowed use limits."  A person using a substitute that is acceptable subject to narrowed use limits in applications and end-uses that are not consistent with the narrowed use limit is using the substitute in an unacceptable manner and is in violation of section 612 of the CAA and EPA's SNAP regulations.
       	The Agency publishes its SNAP program decisions in the Federal Register (FR).  EPA publishes decisions concerning substitutes that are deemed acceptable subject to use restrictions (use conditions and/or narrowed use limits), or for substitutes deemed unacceptable, as proposed rulemakings to allow the public opportunity to comment, before publishing final decisions.
       	In contrast, EPA publishes decisions concerning substitutes that are deemed acceptable with no restrictions in "notices of acceptability," rather than as proposed and final rules.  As described in the rule initially implementing the SNAP program (59 FR 13044), EPA does not believe that rulemaking procedures are necessary to list alternatives that are acceptable without restrictions because such listings neither impose any sanction nor prevent anyone from using a substitute.
       	Many SNAP listings include "comments" or "further information" to provide additional information on substitutes.  Since this additional information is not part of the regulatory decision, these statements are not binding for use of the substitute under the SNAP program.  However, regulatory requirements so listed are binding under other regulatory programs.  The "further information" classification does not necessarily include all other legal obligations pertaining to the use of the substitute.  While the items listed are not legally binding under the SNAP program, EPA encourages users of substitutes to apply all statements in the "further information" column in their use of these substitutes.  In many instances, the information simply refers to sound operating practices that have already been identified in existing industry and/or building-codes or standards.  Thus, many of the statements, if adopted, would not require the affected user to make significant changes in existing operating practices.
       D.  	Where can I get additional information about the SNAP program?
       For copies of the comprehensive SNAP lists of substitutes or additional information on SNAP, refer to EPA's Ozone Depletion web site at www.epa.gov/ozone/snap/index.html.  For more information on the Agency's process for administering the SNAP program or criteria for evaluation of substitutes, refer to the SNAP final rulemaking published March 18, 1994 (59 FR 13044), codified at subpart G of 40 CFR part 82.  A complete chronology of SNAP decisions and the appropriate citations are found at http://www.epa.gov/ozone/snap/chron.html.
 IX.  Statutory and Executive Order Reviews

      A.	Executive Order 12866: Regulatory Planning and Review

      Under Executive Order (EO) 12866 (58 FR 51735, October 4, 1993), this action is a "significant regulatory action."  It raises novel legal or policy issues arising out of legal mandates, the President's priorities, or the principles set forth in the Executive Order.
      Accordingly, EPA submitted this action to the Office of Management and Budget (OMB) for review under EO 12866 and any changes made in response to OMB recommendations have been documented in the docket for this action.
      B.	Paperwork Reduction Act

      This action does not impose any new information collection burden.  Today's action is an Agency determination.  It contains no new requirements for reporting.  The only new recordkeeping requirement involves customary business practice.  Today's rule requires minimal record-keeping of studies done to ensure that MVAC systems using HFO-1234yf meet the requirements set forth in this rule.  Because it is customary business practice that OEMs conduct and keep on file Failure Mode and Effect Analysis (FMEA) on any potentially hazardous part or system from the beginning of production of a car model until three or more years after production of the model ends, we believe this requirement will not impose an additional paperwork burden.  However, the Office of Management and Budget (OMB) has previously approved the information collection requirements contained in the existing regulations in subpart G of 40 CFR part 82 under the provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. and has assigned OMB control numbers 2060-0226. The OMB control numbers for EPA's regulations are listed in 40 CFR Part 9.

	C.	Regulatory Flexibility Act

      The Regulatory Flexibility Act (RFA) generally requires an agency to prepare a regulatory flexibility analysis of any rule subject to notice and comment rulemaking requirements under the Administrative Procedure Act or any other statute unless the agency certifies that the rule will not have a significant economic impact on a substantial number of small entities.  Small entities include small businesses, small organizations, and small governmental jurisdictions.
      For purposes of assessing the impacts of today's rule on small entities, small entity is defined as: (1) A small business as defined by the Small Business Administration's (SBA) regulations at 13 CFR 121.201; for NAICS code 336111 (Automobile manufacturing), a small business has <1000 employees; for NAICS code 336391 (Motor Vehicle Air-Conditioning Manufacturing), a small business has <750 employees; (2) a small governmental jurisdiction that is a government of a city, county, town, school district or special district with a population of less than 50,000; and (3) a small organization that is any not-for-profit enterprise which is independently owned and operated and is not dominant in its field.
	After considering the economic impacts of today's final rule on small entities, I certify that this action will not have a significant adverse economic impact on a substantial number of small entities.  The only new requirement on small entities in this final rule is a requirement specifying the type of unique service fittings required when servicing MVAC systems using the refrigerant HFO-1234yf.  Existing regulations at appendix D to subpart G of 40 CFR part 82 already require that there be unique service fittings for each refrigerant used in MVAC systems.  Thus, the costs of purchasing new unique fittings for this refrigerant have already been imposed by the pre-existing regulation.  This rule specifies the requirements for which type of unique fitting, in accordance with the fittings provided to EPA by the manufacturer.  These fittings are part of the SAE J639 standard.  It is not clear that there would be any cost differential between these specific unique fittings and others that the automotive industry could adopt instead.  Thus, cost impacts of this final rule on small entities are expected to be small.  This final rule is expected to relieve burden for some small entities, such as car repair shops, by allowing them the flexibility to use a new refrigerant that otherwise would have been prohibited under previous requirements at appendix B to subpart G of 40 CFR part 82 and by allowing them to use the easy-to-use "quick-connect" fittings for this refrigerant.  Other final rule requirements apply to original equipment manufacturers, which are not small entities.  These final rule requirements are the least burdensome option for regulation.
      Original equipment manufacturers are not mandated to move to MVAC systems using HFO-1234yf.  EPA is simply listing HFO-1234yf as an acceptable alternative with use conditions in new MVAC systems.  This rule allows the use of this alternative to ozone-depleting substances in the MVAC sector and outlines the conditions necessary for safe use.  By approving this refrigerant under SNAP, EPA provides additional choice to the automotive industry which, if adopted, would reduce the impact of MVACs on the global environment.  This rulemaking does not mandate the use of HFO-1234yf as a refrigerant in new MVACs.
      	D.	Unfunded Mandates Reform Act
	Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public Law 104-4, establishes requirements for Federal agencies to assess the effects of their regulatory actions on State, local, and tribal governments and the private sector. Under section 202 of the UMRA, EPA generally must prepare a written statement, including a cost-benefit analysis, for proposed and final rules with ``Federal mandates'' that may result in expenditures to State, local, and tribal governments, in the aggregate, or to the private sector, of $100 million or more in any one year.  Before promulgating an EPA rule for which a written statement is needed, section 205 of the UMRA generally requires EPA to identify and consider a reasonable number of regulatory alternatives and adopt the least costly, most cost-effective or least burdensome alternative that achieves the objectives of the rule.  The provisions of section 205 do not apply when they are inconsistent with applicable law.  Moreover, section 205 allows EPA to adopt an alternative other than the least costly, most cost-effective or least burdensome alternative if the Administrator publishes with the final rule an explanation why that alternative was not adopted.  Before EPA establishes any regulatory requirements that may significantly or uniquely affect small governments, including tribal governments, it must have developed under section 203 of the UMRA a small government agency plan.  The plan must provide for notifying potentially affected small governments, enabling officials of affected small governments to have meaningful and timely input in the development of EPA regulatory proposals with significant Federal intergovernmental mandates, and informing, educating, and advising small governments on compliance with the regulatory requirements.
      EPA has determined that this rule does not contain a Federal mandate that may result in expenditures of $100 million or more for State, local, and tribal governments, in the aggregate, or the private sector in any one year.  Today's rule does not affect State, local, or tribal governments.  The enforceable requirements of today's rule related to system design and documentation of the safety of alternative MVAC systems affect only a small number of original equipment manufacturers.  Further, those requirements are consistent with requirements that the automotive industry has already adopted through consensus standards of SAE International.  We expect that most manufacturers of automobiles and MVAC systems would attempt to meet those requirements or something very similar, even in the absence of EPA's regulations.  The only requirement that is applied more widely than for original equipment manufacturers is a requirement specifying the type of unique service fittings required when servicing MVAC systems using the refrigerant HFO-1234yf.  Existing regulations at appendix D to subpart G of 40 CFR part 82 already require that there be unique service fittings for each refrigerant used in MVAC systems.  The fittings required in this final rule are part of the SAE J639 standard.  Thus, the costs of this rule are consistent with standard industry practice and are expected to be much less than $100 million per year.
      This action provides additional options allowing greater flexibility for industry in designing consumer products.  The impact of this rule on the private sector will be less than $100 million per year.  Thus, today's rule is not subject to the requirements of sections 202 and 205 of the UMRA.  EPA has determined that this rule contains no regulatory requirements that might significantly or uniquely affect small governments. This regulation applies directly to facilities that use these substances and not to governmental entities.  This rule does not mandate a switch to HFO-1234yf and the limited direct economic impact on entities from this rulemaking is less than $100 million annually.
 	E.	Executive Order 13132: Federalism

      Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August 10, 1999), requires EPA to develop an accountable process to ensure ``meaningful and timely input by State and local officials in the development of regulatory policies that have federalism implications.'' ``Policies that have federalism implications'' is defined in the Executive Order to include regulations that have ``substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government.''
      This action does not have federalism implications.  It will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government, as specified in Executive Order 13132.  This regulation applies directly to facilities that use these substances and not to governmental entities.  Thus, Executive Order 13132 does not apply to this rule.

 	F.	Executive Order 13175:  Consultation and Coordination with Indian Tribal Governments

      Executive Order 13175, entitled ``Consultation and Coordination with Indian Tribal Governments'' (59 FR 22951, November 6, 2000), requires EPA to develop an accountable process to ensure ``meaningful and timely input by tribal officials in the development of regulatory policies that have tribal implications.''  This final rule does not have tribal implications, as specified in Executive Order 13175.  It does not significantly or uniquely affect the communities of Indian tribal governments, because this regulation applies directly to facilities that use these substances and not to governmental entities. Thus, Executive Order 13175 does not apply to this rule.

      G.	Executive Order 13045: Protection of Children from Environmental Health Risks and Safety Risks

	This action is not subject to EO 13045 (62 FR 19885, April 23, 1997) because it is not economically significant as defined in EO 12866, and because the Agency does not believe the environmental health or safety risks addressed by this action present a disproportionate risk to children.  This action's health and risk assessments are discussed in sections V and VII.D of the preamble and in documents EPA-HQ-OAR-2008-0664-0036 and HQ-OAR-2008-0664-0038 in the docket for this rulemaking.

      H.	Executive Order 13211: Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, or Use
	This action is not a "significant energy action" as defined in Executive Order 13211 (66 FR 28355 (May 22, 2001)), because it is not likely to have a significant adverse effect on the supply, distribution, or use of energy.  This action could impact manufacturing and repair of MVAC systems using an alternative refrigerant. This rule does not mandate a switch to HFO-1234yf.  Preliminary information indicates that these new systems are more energy efficient than currently available systems in some climates.  Therefore, we conclude that this rule is not likely to have a significant adverse effect on energy supply, distribution or use.

	I.	National Technology Transfer and Advancement Act

	Section 12(d) of the National Technology Transfer and Advancement Act of 1995 ("NTTAA"), Public Law 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 decides not to use available and applicable voluntary consensus standards.

      This rulemaking involves technical standards.  EPA has decided to use SAE International's most recent version of the SAE J1739 and SAE J639 standards.  These standards can be obtained from http://www.sae.org/technical/standards/.  These standards address safety and reliability issues in motor vehicle design, including MVAC systems using alternative refrigerants.

      J.	Executive Order 12898:  Federal Actions to Address Environmental Justice in Minority Populations and Low-Income Populations

      Executive Order (EO) 12898 (59 FR 7629 (Feb. 16, 1994)) establishes federal executive policy on environmental justice.  Its main provision directs federal agencies, to the greatest extent practicable and permitted by law, to make environmental justice part of their mission by identifying and addressing, as appropriate, disproportionately high and adverse human health or environmental effects of their programs, policies, and activities on minority populations and low-income populations in the United States.
      EPA has determined that this final rule will not have disproportionately high and adverse human health or environmental effects on minority or low-income populations because it increases the level of environmental protection for all affected populations without having any disproportionately high and adverse human health or environmental effects on any population, including any minority or low-income population. HFO-1234yf is a non-ozone-depleting substance with a low GWP.  Based on the toxicological and atmospheric work described earlier, HFO-1234yf will not have any disproportionately high and adverse human health or environmental effects on any population, including any minority or low-income population.  This final rule requires specific use conditions for MVAC systems, if car manufacturers chose to make MVAC systems using this low GWP refrigerant alternative.
K.	Congressional Review Act
The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the Small Business Regulatory Enforcement Fairness Act of 1996, generally provides that before a rule may take effect, the agency promulgating the rule must submit a rule report, which includes a copy of the rule, to each House of the Congress and to the Comptroller General of the United States.  EPA will submit a report containing this rule and other required information to the U.S. Senate, the U.S. House of Representatives, and the Comptroller General of the United States prior to publication of the rule in the Federal Register.  A Major rule cannot take effect until 60 days after it is published in the Federal Register.  This action is not a "major rule" as defined by 5 U.S.C. 804(2).  This rule will be effective [insert date 60 days after publication].
XI. References
      The documents below are referenced in the preamble.  All documents are located in the Air Docket at the address listed in section titled ``ADDRESSES'' at the beginning of this document.  Unless specified otherwise, all documents are available in Docket ID No. EPA-HQ-OAR-2008-0664 at http://www.regulations.gov.
Benesch et al., 2002.  Investigation of Effects of Trifluoroacetate on Vernal Pool Ecosystems.  Environ. Tox and Chem. Vol. 21, No. 3 pp. 640-647.  2002.  Available online at http://www3.interscience.wiley.com/journal/122678081/abstract?CRETRY=1&SRETRY=0

Benouali et al., 2008.  "A/C System Control Strategies for Major Refrigerant Options" June 11, 2008, Alternative Refrigerant Systems Symposium Phoenix, AZ.  Available online at http://www2.dupont.com/Refrigerants/en_US/assets/downloads/SmartAutoAC/2008_SAE_ARSS_Valeo_Eval.pdf

Besnard, S., 1996.  Full Flammability Test of Gases and Gas Mixtures in Air.  CERN.  European Organization for Nuclear Research.  1996.  Available online at http://cdsweb.cern.ch/record/1217583/files/CM-P00055900.pdf

Boutonnet et al., 1999.  "Environmental Risk Assessment of Trifluoroacetic Acid," Human and Ecological Risk Assessment, Feb. 1999.  Available online at http://www.informaworld.com/smpp/content~db=all~content=a922749285~frm=abslink.

CARB, 2008.  Technical Support Document "Staff Analysis on Emissions and Economic Impact of Proposed Regulation for Small Containers of Automotive Refrigerant." Appendix G to Certification Procedures for Small Containers of Automotive Refrigerant. California Air Resources Board, effective March 10, 2010. Document incorporated by reference in California Code of Regulations (CCR), title 17, sections 95360 through 95370. Available online at http://www.arb.ca.gov/regact/2009/hfc09/hfc09.htm.

Carter, 2009.  Investigation of Atmospheric Ozone Impacts of 2,3,3,3-Tetrafluoropropene.  Final report to Honeywell International Contract UCR-09010016.  William Carter, University of California, Riverside CA.  June 2, 2009.  Available online at http://www.cert.ucr.edu/%7Ecarter/pubs/YFrept.pdf.

Ceviz and Yuksel, 2005.  "Cyclic variations on LPG and gasoline-fuelled lean burn SI engine."  Renewable Energy.  In press.  Available online at http://www.pm-kbase.com/articles/LPGsdarticle(8).pdf.

Clodic et al., 2008.  Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor Vehicle Air Conditioning Systems.  D. Clodic, A. Tremoulet, Y, Riachi, D. Sousa, L. Palandre, A. Garnier,  S.Clodic and M. Lansard.  Prepared under CARB Agreement No. 06-341. December, 2008.  Available online at http://www.arb.ca.gov/research/apr/past/06-341.pdf.

CRP, 2008.  Risk Assessment for Alternative Refrigerants HFO-1234yf  Phase II. Prepared for SAE International Cooperative Research Program 1234 by Gradient Corporation.  February 26, 2008.  Docket number EPA-HQ-OAR-2008-0664-0008

CRP, 2009.  Risk Assessment for Alternative Refrigerants HFO-1234yf and R-744 (CO2)  Phase III. Prepared for SAE International Cooperative Research Program 1234 by T. Lewandowski, Gradient Corporation.  December 17, 2009.  Docket number EPA-HQ-OAR-2008-0664-0056.2

DuPont, 2008.  DuPont internal testing.  Cited in docket number EPA-HQ-OAR-2008-0664-0052.1.

Hamner Institutes, 2007.  Toxicogenomic assessment of the carcinogenic potential of 2,3,3,3-tetrafluoropropene.  The Hamner Institutes for Health Sciences.  January 5, 2007.  Docket numbers EPA-HQ-OAR-2008-0664-0030 through -0030.6.

Honeywell, 2010a.  Comment on EPA Proposed Rule (simulated vehicle service leak testing and exposure study).  Docket ID: EPA-HQ-OPPT-2008-0918-0088.

Honeywell, 2010b.  Response to EPA questions.  Docket ID: EPA-HQ-OPPT-2008-0918-0096.

ICF, 2008.  ICF International.  2008.  Air Conditioning Refrigerant Charge Size to Passenger Compartment Volume Ratio Analysis.  Docket number EPA-HQ-OAR-2008-0664-0003

ICF, 2009.  ICF International.  2009.  Revised Final Draft Assessment of the Potential Impacts of HFO-1234yf and the Associated Production of TFA on Aquatic Communities and Local Air Quality.  Docket number EPA-HQ-OAR-2008-0664-0037

ICF, 2010a.  ICF International.  2010.  Summary of HFO-1234yf Emissions Assumptions.

ICF, 2010b.  ICF International.  2010.  Revised Assessment of the Potential Impacts of HFO-1234yf and the Associated Production of TFA on Aquatic Communities, Soil and Plants, and Local Air Quality.

ICF, 2010c.  ICF International.  2010.  Sensitivity Analysis CMAQ results on projected maximum TFA rainwater concentrations and maximum 8-hr ozone concentrations.

ICF, 2010d.  ICF International.  2010.  Analysis of Potential Impacts of Aldehydes as Breakdown Products from HFO-1234yf.

ICF, 2010e.  ICF International.  2010.  Summary of Updates to the Vintaging Model that Impacted HFO-1234yf Emissions Estimates.

IPCC, 2007.  Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, 2007.  Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.).  Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.  Available online at http://www.ipcc.ch/publications_and_data/ar4/wg1/en/contents.html .

JAMA, 2008.  "LCCP Result from JAMA," Japan Automobile Manufacturers Association , T. Ikegami; K. Inui; K. Aoki. VDA Alternative Refrigerant Winter Meeting, Saalfelden, Austria, February 13-14, 2008.  Available online at http://www.vda-wintermeeting.de/fileadmin/downloads2008/presentations/Tohru_Ikegami_Toyota_Kenta_Aoki_Nissan_JAMA.pdf  (begins, p. 23)

JAMA-JAPIA, 2008.  "New Refrigerants Evaluation Results" Japan Automobile Manufacturers Association-Japan Auto Parts Industries Association Consortium.  T. Ikegami, M. Iguchi, K. Aoki, K. Iijima; VDA Alternative Refrigerant Winter Meeting, Saalfelden, Austria, February 13-14, 2008.  Available online at http://www.vda-wintermeeting.de/fileadmin/downloads2008/presentations/Tohru_Ikegami_Toyota_Kenta_Aoki_Nissan_JAMA.pdf .

Kajihara et al., 2010.  "Estimation of environmental concentrations and deposition fluxes of R-1234-YF and its decomposition products emitted from air conditioning equipment to atmosphere".  H. Kajihara, K. Inoue, K. Yoshida, R. Nagaosa.  February 17-19, 2010.  2010 International Symposium on Next-generation Air Conditioning and Refrigeration Technology.  Docket number EPA-HQ-OAR-2008-0664-0114.1

Kirkland et al. (2005) Evaluation of a battery of three in vitro genotoxicity tests to determine rodent carcinogens and non-carcinogens. I. Sensitivity, specificity and relative predictivity, Mutation Research, 584, 1-256.  Available online at www.sciencedirect.com.

Luecken et al., 2009. Luecken, D.J., Waterland, R.L., Papasavva, S., Taddonio, K.N., Hutzell, W.T., Rugh, J.P., Andersen, S.O. 2009.  Ozone and TFA Impacts in North America from the Degradation of 2,3,3,3-Tetrafluoropropene (HFO-1234yf), A Potential Greenhouse Gas Replacement. Environ. Sci. Technol., submitted for publication.  Docket number EPA-HQ-OAR-2008-0664-0112.3
Meyer, 2008.  "R-1234yf System Enhancements and Comparison to R-134a." 2008, Alternative Refrigerant Systems Symposium Phoenix, AZ  Available online at http://www2.dupont.com/Refrigerants/en_US/assets/downloads/SmartAutoAC/2008_SAE_ARSS_Visteon_Eval.pdf

Monforte et al., 2008 "Updated situation about alternative refrigerant evaluation" June 10-12, 2008, Alternative Refrigerant Systems Symposium Phoenix, AZ.  http://www2.dupont.com/Refrigerants/en_US/assets/downloads/SmartAutoAC/2008_SAE_ARSS_Renault_Fiat_PSA_Eval.pdf

Nielsen et al., 2007.  Nielsen, O.J., Javadi, M.S., Sulbaek Andersen, M.P., Hurley, M.D., Wallington, T.J., Singh, R. 2007. Atmospheric chemistry of CF3CF=CH2: Kinetics and mechanisms of gas-phase reactions with Cl atoms, OH radicals, and O3. Chemical Physics Letters 439, 18-22.  Available online at http://www.cogci.dk/network/OJN_174_CF3CF=CH2.pdf.
NRC, 1981.  Atmosphere-Biosphere Interactions:  Toward a Better Understanding of the Ecological Consequences of Fossil Fuel Combustion.  Committee on the Atmosphere and the Biosphere, Board on Agriculture and Renewable Resources, Commission on Natural Resources, National Research Council.  1981.  Available from NRC Press or online at http://www.nap.edu/catalog.php?record_id=135.

NRC, 1996.  NRC Toxicity of Alternatives to Chlorofluorocarbons: HFC-134a and HCFC-123 (1996).  Available online at http://www.nap.edu/openbook.php?record_id=9268&page=29.
NRC, 2004.  Acute Exposure Guideline Levels for Selected Airborne Chemicals: Volume 4 (2004) Board on Environmental Studies and Toxicology.  The National Academies Press.  Available online at http://www.nap.edu/openbook.php?record_id=10902&page=127#p2000a02f9960127001.

Orkin et al., 1997.  Rate constants for the reactions of OH with HFC-245cb (CH3CF2CF3) and some fluoroalkenes (CH2CHCF3, CH2CFCF3, CF2CFCF3, and CF2CF2),  Journal of Physical Chemistry A 101 (1997), pp.9118-9124. Available online at http://pubs.acs.org/doi/abs/10.1021/jp971994r.

Papadimitriou et al., 2007.  CF3CF=CH2 and (Z)-CF3CF=CHF:  temperature dependent OH rate coefficients and global warming potentials.  V. Papadimitriou, R Talukdar, R. Portmann, A. Ravishankara and J. Burkholder.  Phys. Chem. Chem. Phys., 2007, Vol. 9, p. 1 - 13.  Docket number EPA-HQ-OAR-2008-0664-0002.  Available online at http://pubs.rsc.org/en/Content/ArticleLanding/2008/CP/b714382f.

Papasavva et al., 2009.  Estimated 2017 Refrigerant Emissions of 2,3,3,3-tetrafluoropropene (HFC-1234yf) in the United States Resulting from Automobile Air Conditioning.  Environ. Sci. Technol. 2009.  43 pp. 9252-9259.  Docket number EPA-HQ-OAR-2008-0664-0112.1.  Available online at http://www.ncbi.nlm.nih.gov/pubmed/20000517.

Parodi et al., 1982.  Predictive ability of the autoradiographic repair assay in rat liver cells compared with the Ames test ; S. Parodi; M. Taningher; C. Balbi ;L. Santi  . Journal of Toxicology and Environmental Health, Vol. 10, Issue 4 & 5 October 1982 , pages 531  -  539.  Available online at http://www.informaworld.com/smpp/content~db=all~content=a915968516.

Ravishankara et al., 1993.  Do Hydrofluorocarbons Destroy Stratospheric Ozone?  A. R. Ravishankara, Andrew A. Turnipseed, Niels R. Jensen, Stephen Barone, Michael Mills, Carleton J. Howard, and Susan Solomon. Science,  Vol. 263. no. 5143, pp. 71  -  75.  January 4, 1994.  Available online at http://www.sciencemag.org/cgi/content/abstract/263/5143/71.

Rhasa and Zellner, 1987.  Atmospheric Oxidation of Hydrocarbons. Free Radical Research 1987, Vol. 3, No. 1-5:  Pages 199-209. Available online at http://informahealthcare.com/doi/abs/10.3109/10715768709069785 .

Sciance, 2010.  "General Motors R-1234yf Implementation," Presentation by Fred Sciance, General Motors to EPA staff.  October 28, 2010.  Docket number EPA-HQ-OAR-2008-0664-0138.

Spatz, 2008.  Spatz, M and B. Minor 2008 "HFO-1234yf: A Low GWP Refrigerant for MAC", VDA Winter meeting.  Available online at http://www2.dupont.com/Refrigerants/en_US/assets/downloads/SmartAutoAC/MAC_VDA08_HFO_1234yf.pdf.

SROC, 2005.  Chapter 3 from Safeguarding the Ozone Layer and the Global Climate System:  Special Report of the Intergovernmental Panel on Climate Change.  Edited by Bert Metz, Lambert Kuijpers, Susan Solomon, Stephen O. Anderson, Ogunlade Davidson, Jose Pons, David de Jager, Tahl Kestin, Martin Manning and Leo Meyer.  Cambridge University Press.  2005.  Available online at http://www.cambridge.org/catalogue/catalogue.asp?isbn=9780521682060.

TNO, 2005.  Sub-acute (2-week) Inhalation Toxicity Study with HFO-1234yf in Rats.  2005.  Docket number EPA-HQ-OAR-2008-0664-0020 and attachments -0020.1 through -0020.4.

TNO, 2007a.  Sub-chronic (13-week) inhalation toxicity study with HFO-1234yf in rats.  2007. Docket number EPA-HQ-OAR-2008-0664-0022 and attachments -0022.1 through -0022.5.

TNO, 2007b.  Prenatal Developmental Inhalation Toxicity Study with HFO-1234yf in Rats.  2007. Docket number EPA-HQ-OAR-2008-0664-0023 and attachments -0023.1 through -0023.9.

 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 Environmental 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 Climate 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, Honeywell re:  Summary of our conference call on service fittings for HFO-1234yf.  November 8, 2010.

US EPA, 2010c.  Clarifying questions for Honeywell on Exposure Study.  Docket number EPA-HQ-OPPT-2008-0918-0095.

Wallington et al., 2008.  Emissions of CO2, CO, NOx, HC, PM, HFC-134a, N2O and CH4 from the Global Light Duty Vehicle Fleet.  Meteorologische Zeitschrift 17. 109-116.  Available online at http://www.schweizerbart.de/resources/downloads/paper_free/56618.pdf

Wallington et al., 2010.  "Estimated Photochemical Ozone Creation Potentials (POCPs) of CF3CF=CH2 (HFO-1234yf) and Related Hydrofluoroolefins (HFOs)."  T. Wallington, M. Andersen, O. Nielsen.  Atmospheric Environment. Docket number EPA-HQ-OAR-2008-0664-0084.2.  Available online at http://www.sciencedirect.com or at doi:10.1016/j.atmosenv.2010.01.040.

 Weissler, P., 2008.  "Consensus Building on Refrigerant Type."  Automotive Engineering International.  9: 30-32.  Docket number EPA-HQ-OAR-2008-0664-
Protection of Stratospheric Ozone:  New Substitute in the Motor Vehicle Air Conditioning Sector under the Significant New Alternatives Policy (SNAP) Program (Page 128 of 130)

      0006.
WIL, 2006.  Acute Cardiac Sensitization Study of [name redacted] and HFO-1234yf in Dogs.  WIL Laboratories, 2006.  Docket number EPA-HQ-OAR-2008-0664-0019 and attachments -0019.1 through -0019.2.

List of Subjects in 40 CFR Part 82
	Environmental protection, Administrative practice and procedure,
Air pollution control, 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--PROTECTION OF STRATOSPHERIC OZONE
1. The authority citation for part 82 continues to read as follows:
   Authority: 42 U.S.C. 7414, 7601, 7671-7671q.
Subpart G--Significant New Alternatives Policy Program
2.  The first table in Subpart G to Appendix B of Part 82 is amended by adding one new entry to the end of the table to read as follows:

 Appendix 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 and light-duty trucks only)
 HFO-1234yf as a substitute for CFC-12
 Acceptable subject to use conditions
 Manufacturers must adhere to all of the safety requirements listed in the Society of Automotive Engineers (SAE) Standard J639 (adopted 2011),  including requirements for:  unique fittings, flammable refrigerant warning label, high-pressure compressor cutoff switch and pressure relief devices.  For connections with refrigerant containers of 20 lbs or greater, use fittings consistent with SAE J 2844.

 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.

Additional training for service technicians recommended.

Observe requirements of Significant New Use Rule at 40 CFR 721.10182.

HFO-1234yf is also known as 2,3,3,3-tetrafluoro-prop-1-ene (CAS No 754-12-1).

3.  Appendix B to Subpart G is amended by revising the entry for ``CFC-12 Motor Vehicle Air Conditioners (Retrofit and New Equipment/NIKs)'' in the table titled ``Refrigerants--Unacceptable Substitutes'' to read as follows:

                    Refrigerants--Unacceptable Substitutes

                                   End -use
                                  Substitute
                                   Decision
                                   Comments
                    *                   *                   *                   *                  *                   *                   *
CFC-12 Motor Vehicle Air Conditioners (Retrofit and New Equipment/NIKs)
R-405A.......
Unacceptable.
R-405A contains R-c318, a PFC, which has an extremely high GWP and lifetime. Other Substitutes exist which do not contain PFCs.

Hydrocarbon Blend B....
Unacceptable.
Flammability is a serious concern.  Data have not been submitted to demonstrate it can be used safely in this end-use.

Flammable Substitutes, other than R-152a or HFO-1234yf in new equipment.
Unacceptable.
The risks associated with using flammable substitutes (except R-152a and HFO-1234yf) in this end-use have not been addressed by a risk assessment. R-152a and HFO-1234yf may be used in new equipment with the use conditions in appendix B to this subpart.

[FR Doc.              ]
BILLING CODE 6560-50-P