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Page 1 of 29 **6560 -**  **50 -**  **P ENVIRONMENTAL PROTECTION AGENCY** 

**40 CFR Part 51 [**  **EPA -**  **HQ -**  **OAR -**  **2010 -**  **0605 ; FRL**  **- ]** 

**RIN 2060 -** **AQ38 Air Quality: Revision to Definition of Volatile Organic Compounds**  **– Exclusion of**  **trans -**  **1,3,3,3 -**  **tetrafluoropropene and 2,3,3,3**  **- tetrafluoropropene**  **AGENCY:** Environmental Protection Agency (EPA). **ACTION:** Proposed rule . **SUMMARY:** EPA is proposing to revise the Agency’s definition of volatile organic compounds (VOCs) for purposes of preparing s tate implementation plans (SIPs) to attain the national ambient air quality standard s for ozone under Title I of the Clean Air Act (CAA). This proposed revision would add 2,3,3,3 - tetrafluoropropene (also known as HFO - 1234yf) and trans - 1,3,3,3 - tetrafluoropropene (also known as HFO - 1234ze) to the list of compounds excluded from the definition of VOC on the basis that these compounds make a negligible contribution to tropospheric ozone formation. **DATES:** Comments must be received on or before **[INSERT DATE 30 DAYS AFTER PUBLICATION IN THE**  **FEDERAL REGISTER ]**  . Public Hearing : If anyone contacts us requesting to speak at a public hearing on or before **[ INSERT DATE 15 DAYS AFTER PUBLICATION IN**  **THE FEDERAL REGISTER** ], we will hold a public hear ing in Research***E.O. 12866 Review

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Page 2 of 29 Triangle Pa r k, North Carolina . Additional information about the hearing would be published in a subsequent Federal Register notice. **ADDRESSES:** Submit your comments, identified by Docket ID No. EPAHQ - OAR- 2010 - 0605, by one of the following methods:

 www.regulations.gov . Follow the on - line instructions for submitting comments.

 E -mail : a - and - r - Docket@epamail.epa.gov, Attention Docket ID No. EPA- HQ - OAR- 2010 - 0605.

 Fax : 202 - 566 - 1541, Attention Docket ID No. EPA- HQ - OAR- 2010 - 0605.

 Mail : Docket ID No. EPA- HQ - OAR- 2010 - 0605, Environmental Protection Agency, Mailcode: 6102T, 1200 Pennsylvania Ave., NW, Washington, DC 20460 .  Hand Delivery : EPA Docket Center, U.S. Environmental Protection Agency, 1301 Constitution Avenue, NW, Room: 3334, Mail Code: 6102T, Washington, D.C. 20460, Attention Docket ID No. EPA- HQ OAR- 2010 - 0605 . Such deliveries are only accepted during the Docket ’s normal hours of operation, and special arrangements should be made for deliveries of boxed information. Instructions : Direct your comments to Docket ID No. EPA- HQ - OAR- 2010 - 0605. EPA's policy is that all comments received will be included in the public docket without change and may be made available online at***E.O. 12866 Review

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Page 3 of 29 www.regulations.gov , including any personal information provided, unless the comment includes information claimed to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected through www.regulations.gov , or e -mail. The www.regulations.gov website is an “anonymous access” system, which means EPA will not know your identity or c ontact information unless you provide it in the body of your comment. If you send an e mail comment directly to EPA without going through www.regulations.gov , your e -mail address will be automatically captured and included as part of the comment that is pl aced in the public docket and made available on the Internet. If you submit an electronic comment, EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD - ROM you submit. If EPA cannot rea d your comment due to technical difficulties and cannot contact you for clarification, EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses. For additional information about EPA’s public docket , visit the EPA Docket Center homepage at http://www.epa.gov/epahome/dockets.htm . Docket: All documents in the docket are listed in the www.regulations.gov index. Although listed in the index, some***E.O. 12866 Review

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Page 4 of 29 information is not publicly available, i.e., CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighte d material, will be publicly available only in hard copy. Publicly available docket materials are available either electronically in www.regulations.gov or in hard copy at the Docket ID No. EPA- HQ - OAR- 2010 - 0605, EPA /DC, EPA West, Room 3334, 1301 Constitution Ave., NW, Washington, DC. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is (202) 566 - 1744, and the telephone number for the Docket ID No. EPAHQ - OAR- 2010 - 0605 is (202) 566 - 1742. **FOR FURTHER INFORMATION CONTACT** : David Sanders , Office of Air Quality Planning and Standards, Air Quality Policy Division, Mail C ode C539 - 0 1 , Research Triangle Park, NC 27711; telephone : (919) 541 - 3356 ; fax number: 919 - 541 - 0824; e -mail address: sanders.dave@epa.gov . **SUPPLEMENTARY INFORMATION: I. General Information**  A. Does this action apply to me ? Entities potentially affected by this proposed rule include, but not necessarily limited to, states (typically state air pollution control agencies) that control VOCs, and industries involved in the***E.O. 12866 Review

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Page 5 of 29 manufacture or use of refrigerants, aerosol propellants, and blowing agents for insulating foams . Industry group SIC a NAICS b Refrigerants Aerosol propellants Blowing agents 2869, 358 2869 2869, 3079 233415, 238220, 3411, 44811

3411 326140, 326150, 3411

a Standard Industrial Classification. b North American Industry Classification System. This proposed rule is applicable to all manufacturers, distributors, and users of these chemical compounds. In addition to this rule, the use of these compounds is subject to restrictions under other parts of the CAA and the Toxic Substances Control Act ( TSCA). Specifically, the use of these compounds as aerosol propellants, blowing agents, or refrigerants, or any other use in which they would substitute for chlorofluorocarbons, hydrochlorofluorocarbons, or their substitutes, is subject to restrictions under the Significant New Alternatives Policy (SNAP) program (CAA § 612; 40 CFR 82 subpart G). The SNAP program has issued determination s for trans - 1,3,3,3 - tetrafluoropropene (HFO - 1234ze) as a suitable foam and refrigerant substitute ( 74 FR 50129, September 30 , 2009; 75 FR 34017, June 16, 2010) and a final approval for 2,3,3,3 -***E.O. 12866 Review

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Page 6 of 29 tetrafluoropropene (HFO - 1234yf) , (76 FR 17488, Mar ch 29, 2011) , as a substitute for use in the motor vehicle air conditioning end - use as a replacement for ozone depleting substances. Furthermore, HFO - 1234yf is subject to a Significant New Use Rule (SNUR) under TSCA.(75 FR 65987, Oct ober 27, 2010). The implications of these other regulations are discussed in more detail in Section III. B . What should I consider as I prepare my comments for EPA ? Submitting CBI : Do not submit this information to EPA through www. regulations.gov or e -mail. Clearly mark the part or all of the information that you claim to be CBI. For CBI information in a disk or CD ROM that you mail to EPA, mark the outside of the disk or CD ROM as CBI and then identify electronically within the disk or CD ROM the specific information that is claimed as CBI. In addition to one complete version of the comment that includes information claimed as CBI, a copy of the comment that does not contain the information claimed as CBI must be submitted for inclusion in the public docket. Information so marked will no t be disclosed except in accordance with procedures set forth in 40 CFR part 2. C. How can I find information about a possible public hearing? Public Hearing : To request a public hearing or information pertaining to a public hearing on this document, contact Ms. Pamela S. Long, Air Quality Policy Division, Mail code C504 - 03, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711,***E.O. 12866 Review

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Page 7 of 29 telephone ( 919) 541 - 0641, facsimile number (919) 541 - 5509, electronic e -mail address: long.pam@epa.gov . D. How is this preamble organized? The information presented in this pre amble is organized as follows: I. General Information A. Does this action apply to me? B. What should I consider as I prepare my comments for EPA? C. How can I find information about a possible public hearing? D. How is this preamble organized? II . Background A. Petition to list 2,3,3,3 - tetrafluoropropene B. Petition to list trans - 1,3,3,3 - tetrafluoropropene III. EPA Response to the Petition s I V . Proposed Action V. Statutory and Executive Order Reviews A. Executive Order 12866: Regulatory Planning and Review B. Paperwork Reduction Act C. Regulatory Flexibility Act D. Unfunded Mandates Reform Act E. Executive Order 13132: Federalism F. Executive Order 13175: Consultation and Coordination with Indian Tribal Governments G. Executive Order 13045: Protection of Children from Environmental Health and Safety Risks H. Executive Order 13211: Actions that Significantly Affect Energy Supply, Distribution, or Use I. National Technology Transfe r and Advancement Act J. Executive Order 12898: Federal Actions to Address Enviro nmental Justice in Minority Populations and Low - Income Populations. **II. Background** Tropospheric ozone, commonly known as smog, is formed when VOCs and nitrogen oxides (NOx) react in the atmosphere in the presence of sunlight . Because of the harmful hea lth effects of ozone, EPA and state governments limit the amount of VOCs that can be released into***E.O. 12866 Review

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Page 8 of 29 the atmosphere. The VOCs are those organic compounds of carbon which form ozone through atmospheric photochemical reactions. Different VOCs have different l evels of reactivity -- that is, they do not react to form ozone at the same speed or do not form ozone to the same extent. Some VOCs react slowly, or form less ozone ; therefore , changes in their emissions have limited effects on local or regional ozone pol lution episodes. It has been EPA’s policy that organic compounds with a negligible level of reactivity should be excluded from the regulatory definition of VOC so as to focus VOC control efforts on compounds that do significantly increase ozone concentrati ons. EPA also believes that exempting such compounds creates an incentive for industry to use negligibly reactive compounds in place of more highly reactive compounds that are regulated as VOCs. EPA lists these negligibly reactive compounds in its regulati ons (at 40 CFR 51.100(s)) and excludes them from the definition of VOC. The CAA requires the regulation of VOCs for various purposes. Section 302(s) of the CAA specifies that EPA has the authority to define what this term means, and hence what compounds shall be treated as VOC s for regulatory purposes. The policy of excluding negligibly reactive compounds from the VOC definition was laid out in the “Recommended Policy on Control of Volatile Organic Compounds” (42 FR 35314 , July 8, 1977 ) . EPA uses the reactivity of ethane as the***E.O. 12866 Review

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Page 9 of 29 threshold for determining whether a compound has negligible reactivity. Compounds that are less reactive than, or equally reactive to, ethane under certain assumed conditions may be deemed negligibly reactive and th erefore suitable for exemption from the regulatory definition of VOC. Compounds that are more reactive than ethane continue to be considered VOCs for regulatory purposes and therefore subject to control requirements. The selection of ethane as the threshol d compound was based on a series of smog chamber experiments that underlay the 1977 policy. EPA has used three different metrics to compare the reactivity of a specific compound to that of ethane: (i) the reaction rate constant (known as kOH ) with the hydroxyl radical (OH) , (ii) the maximum incremental reactivities (MIR) of ethane and the compound in question expressed on a reactivity per mass basis; and (iii) the MIR of ethane and the compound in question expressed on a reactivity per mole basis. Diffe rences between these three metrics are discussed below. The kOH is the reaction rate constant of the compound with the OH radical in the air. This reaction is typically the first step in a series of chemical reactions by which a compound breaks down in the air and participates in the ozone - forming process. If this step is slow, the compound will likely not form ozone at a very fast rate. The kOH values have long been used by EPA as a measure of***E.O. 12866 Review

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Page 10 of 29 photochemical reactivity and ozone - forming activity, and they have been the basis for most of EPA’s previous exclusions of neg ligibly reactive compounds. The kOH metric is inherently a molar comparison, i.e., it measures the rate at which molecules react. The MIR values, both by mole and by mass, are a more recently developed measure of photochemical reactivity derived from a computer - based photochemical model. This measurement considers the complete ozone forming activity of a compound, not merely the first reaction step. Further explanation of the MIR metric can be found in: W. P. L. Carter, “Development of Ozone Reactivity Scal es for Volatile Organic Compositions,” Journal of the Air & Waste Management Association, Vol . 44, 881 - 899, July 1994. The MIR values for compounds are typically expressed as grams of ozone formed per gram of VOC (mass basis), but may also be expressed as grams of ozone formed per mole of VOC (molar basis). For comparing the reactivities of two compounds, using the molar MIR values considers an equal number of molecules of the two compounds. Alternatively, using the mass MIR values compares an equal mass of the two compounds, which will involve different numbers of molecules, depending on the relative molecular weights. The molar MIR comparison is consistent with the original smog chamber experiments, which compared equal molar concentrations of individual VOCs that underlie the original selection of ethane as the threshold compound. It is***E.O. 12866 Review

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Page 11 of 29 also consistent with previous reactivity determinations based on inherently molar kOH values. By contrast, the mass MIR comparison is more consistent with how MIR values an d other reactivity metrics have been applied in reactivity - based emission limits, such as the national VOC emissions standards for aerosol coatings (73 FR 15604) . Many other VOC regulations contain limits based upon a weight of VOC per volume of product, s uch as EPA’s regulations for limiting VOC emissions from architectural and industrial maintenance coatings (65 FR 7736) . However, the fact that regulations are structured to measure VOC content by weight for ease of implementation and enforcement does not necessarily control whether VOC exemption decisions should be made on a weight basis as well. The choice of the molar basis versus the mass basis for the ethane comparison can be significant. Given the relatively low molecular weight of ethane, use of the mass basis tends to result in more VOCs being classified as “negligibly reactive” than in the case of the molar basis. I n some cases, a compound might be considered less reactive than ethane and eligible for VOC exemption under the mass basis but not under the molar basis. The compounds considered in this proposal, trans - 1,3,3,3 - tetrafluoropropene and 2,3,3,3 - tetrafluoropropene, fall into this category , where the molar MIR value is greater than that of ethane, but the mass MIR value is less than that of ethane.***E.O. 12866 Review

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Page 12 of 29 EPA has considered the choice between a molar or mass basis for the comparison to ethane in past rulemakings and guidance. Most recently, in “Interim Guidance on Control of Volatile Organic Compounds in Ozone State Implementation Plans” published on September 13, 2005 (70 FR 54046), EPA stated: “...a comparison to ethane on a mass basis strikes the right balance betwee n a threshold that is low enough to capture compounds that significantly affect ozone concentrations and a threshold that is high enough to exempt some compounds that may usefully substitute for more highly reactive compounds.

When reviewing compounds th at have been suggested for VOC exempt status, EPA will continue to compare them to ethane using kOH expressed on a molar basis and MIR values expressed on a mass basis.” In this action, EPA is proposing to exempt these compounds using the comparison to et hane on the mass basis MIR value , because MIR values are available for these compounds and EPA believes that this comparison is appropriate. EPA’s 2005 Interim Guidance also notes that , although VOC exemption decisions should be based on the contribution of a compound to tropospheric ozone formation, the EPA may consider whether granting a VOC exemption may lead to other significant risks to human health and the environment that would not be addressed adequately by existing programs or policies. Such consi derations with respect to the two compounds considered here are discussed further in Section III. A. Petition to list 2,3,3,3 - tetrafluoropropene (HFO - 1234yf)***E.O. 12866 Review

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Page 13 of 29 Honeywell, Inc. submitted a petition to EPA on June 29, 2009, requesting that 2,3,3,3 - tetrafluoropropene be exempted from VOC control based on its low reactivity relative to ethane. The petitioner indicated that 2,3,3,3 - tetrafluoropropene may be used as a refrigerant for refrigeration and air - conditioning. Honeywell also indicated that it expects 2,3,3,3 - tetrafluoropropene to be widely used as a replacement for HFC - 134a in motor vehicle air - conditioners (MVAC) , and that 2,3,3,3 - tetrafluoropropene has been specifically developed for this purpose. Honeywell argues that as a replacement for us e in motor vehicle air conditioners there will be an environmental advantage in that the global warming potential (GWP) of 2,3,3,3 - tetrafluoropropene is 4, which is substantially lower than the GWP for HFC - 134a (100 - year GWP = 1430) which 2,3,3,3 - tetrafluo ropropene is designed to replace. Honeywell submitted several documents, including several peer - reviewed journal articles, to support this petition which have been added to the docket for this action. B . Petition to list trans - 1,3,3,3 - tetrafluoropropene (HFO - 1234ze) Honeywell , Inc. also submitted a petition to EPA on December 2, 2009, requesting that trans - 1,3,3,3 - tetrafluoropropene be exempted from VOC control based on its low reactivity relative to ethane. The petitioner indicated that trans - 1,3,3, 3 - tetrafluoropropene may be used in a variety of applications including as a refrigerant, an***E.O. 12866 Review

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Page 14 of 29 aerosol propellant, and a blowing agent for insulating foam. Honeywell submitted several documents, including several peer reviewed journal articles, to support it s petition, all of which have been added to the docket for this action. **III. EPA Response to the Petition s**  EPA’s response to the petitions is based on a consideration of a) the contribution that the chemicals make to tropospheric ozone formation based on a comparison of reactivity metrics , and b) the potential for other significant health and environmental risks that may not be adequately addressed by other programs or policies. Table 1 presents three reactivity metrics for ethan e and for 2,3,3,3 - tetrafluoropropene (CAS 754 - 12 - 1) and trans - 1,3,3,3 - tetrafluoropropene (CAS 29118 - 24 - 9) which are discussed in this proposed rule.

**Table 1 -**  **Reactivities of ethane, trans** **- 1,3,3,3**  **-**

**tetrafluoropropene and 2,3,3,3**  **- tetrafluoropropene**  **Co mpound**  **k OH**  **(cm 3**  **/molecule**   ** sec)** **MIR**

**( g O** **3 /mole**  **VOC) MIR** 

**(g O 3**  **/gram VOC)**  Ethane 2.4 x 10 - 13 8.4 0.28 2,3,3,3 - 10.5 x 10 - 13 31.92 0.28***E.O. 12866 Review

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Page 15 of 29 tetrafluoropropene (HFO - 1234yf) trans - 1,3,3,3 - tetrafluoropropene (HFO - 1234ze) 9.25 x 10 - 13 11.2 0.098

Notes: 1. kOH value for ethane is from: R. Atkinson., D. L. Baulch, R. A. Cox, J. N. Crowley, R. F. Hampson, Jr., R. G. Hynes, M. E. Jenkin, J. A. Kerr, M. J. Rossi, and J. Troe (2004), Summary of evaluated kinetic and photochemical data for atmospheric chemistry. 2. kOH value for trans - 1,3,3,3 - tetrafluoropropene is from: R. Sondergaard, O. J. Nielsen, M. D. Hurley, T. J. Wallington, and R. Singh, “Atmospheric chemistry of trans - CF 3 CH=CHF: kinetics of the gas - phase reactions with Cl atoms, OH radicals, and O 3 .” Chemical Physics Letters, 443 (2007) 199 - 204. 3. kOH value for 2,3,3,3 - tetrafluoropropene is from: O.J. Nielson, M.S. Javadi, M.P. Sulbaek Anderson, M.D. Hurley, T.J. Wallington, R. Singh , “Atmospheric Chemistry of CF 3 CF=CH 2 : kinetics and mechanisms of gas - phase reactions with Cl atoms, OH Radicals, and O 3 ,” Chemical Physical Letters, 439 (2007) 18 - 22. 4. Maximum incremental reactivity or MIR (g O 3 /g VOC) values of ethane, trans - 1,3,3,3 - tetrafluoropropene and 2,3,3,3 - tetrafluor opropene are from: William P. L. Carter, “Development of the SAPRC - 07 chemical mechanism and updated ozone reactivity s cales” (updated 1/27/10) . http://www.engr.ucr.edu/~carter/SAPRC/saprc07.p df . 5. Molar MIR (g O 3 /mole VOC) values were calculated from the mass MIR (g O 3 /g VOC) values by determining the number of moles per gram of the relevant organic compound. From the data in Table 1, it can also be seen that 2,3,3,3 - tetrafluoropropene has a higher kOH value than ethane, meaning that it initially reacts more quickly in the atmosphere than ethane. A molecule of 2,3,3,3 - tetrafluoropropene is also more reactive than a***E.O. 12866 Review

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Page 16 of 29 molecule of ethane, as shown by the molar MIR (g O 3 /mole VOC) values, because equal numbers of moles have equal numbers of molecules. However, a gram of 2,3,3,3 - tetrafluoropropene is less reactive, or creates less ozone on the day of its emission to the atmosphere, than a gram of ethane. This is because 2,3,3,3 - tetrafluoropropene ha s a molecular weight (114) that is more than three times that of ethane (molecular weight 30), thus requiring less than a third the number of molecules of 2,3,3,3 - tetrafluoropropene per gram than the number of molecules of ethane per gram. From the data in Table 1, it can be seen that trans - 1,3,3,3 - tetrafluoropropene has a higher kOH value than ethane, meaning that it initially reacts more quickly in the atmosphere than ethane. A molecule of trans - 1,3,3,3 - tetrafluoropropene is also more reactive than a mole cule of ethane, as shown by the molar MIR (g O 3 /mole VOC) values, since equal numbers of moles have equal numbers of molecules. However, a gram of trans - 1,3,3,3 - tetrafluoropropene is less reactive, or creates less ozone on the day of its emission to the atmosphere, than a gram of ethane. This is because trans - 1,3,3,3 - tetrafluoropropene has a molecular weight (114) that is more than three times that of ethane (mol ecular weight 30), thus requiring less than a third the number of molecules of trans - 1,3,3,3 - tetrafluoropropene per gram than the number of molecules of ethane needed per gram.***E.O. 12866 Review

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Page 17 of 29 For the petitions submitted by Honeywell, the data supports the contention that the reactivit y of the compounds in the petitions are equal to or lower than that of ethane on a mass MIR basis . EPA also considered the results of a peer - reviewed study 1 , in which, among other things, potential air quality impacts from generation of g round - level ozone were modeled using a regional - scale 3 - dimensional atmospheric model. This study found that, if 2,3,3,3 - tetrafluoropropene was used in all automobiles and was only emitted from automobiles, the incremental amount of ozone formed from its degradation in the atmosphere was only 0.01% of total ozone formed during the simulation. The baseline for this analysis was that if 2,3,3,3 - tetrafluoropropene were not used in automobiles, the refrigerant that auto manufacturers would continue to use is HC F - 134a which, because of its slower reaction time, would produce a smaller incremental amount of ozone. However, the study also noted that if 2,3,3,3 - tetrafluoropropene were used in additional applications , e.g., non - vehicle refrigerant applications, its c ontribution to ozone formation would be greater . Thus, the additional information from this study shows that 2,3,3,3 - tetrafluoropropene does produce ozone, but the amount is unlikely to have a significant impact on local air

1 D. Luecken, R. Waterland, S. Papasavva, K. Taddonio, W. Hutzell, J. Rugh, and S. Andersen. Ozone and TFA Impacts in North America from Degradation of 2,3,3,3 - Tetrafluoropropene (HFO - 1234yf), A Potential Greenhouse Gas Replacement. Environ. Sci. Technol. 44, pp. 343 - 349.***E.O. 12866 Review

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Page 18 of 29 quality under current condition s. The study authors also considered the potential for the use of 2,3,3,3 - tetrafluoropropene to increase the deposition of trifluoroacetic acid, a product of atmospheric degradation, into water bodies. The authors concluded that the modeled concentrations of deposited trifluoroacetic acid from the use of 2,3,3,3 - tetrafluoropropene in automobiles were well below levels of concern for aquatic toxicity ; however, the potential for long term accumulation of trifluoroacetic acid in water b odies is still somewhat uncertain. The definition of VOC, and thus the exclusion from that definition, applies to all uses of a chemical. The currently known uses for the chemicals being considered here are regulated as substitutes for stratospheric ozon e - depleting substances (ODS ) under the SNAP program . Under SNAP , EPA reviews all new substitutes for ODS and allows their use in specific applications where the overall risks to human health and the environment associated with their use are comparable to o r less than those of other compounds used in the same manner. EPA’s SNAP program has issued determination s of acceptability for trans - 1,3,3,3 - tetrafluoropropene ( HFO - 1234ze ) as an acceptable substitute for certain ODS in a number of foam blowing end uses and as a refrigerant in non -mechanical heat transfer as stated in Section I.***E.O. 12866 Review

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Page 19 of 29 EPA proposed an approval (74 FR 53445, October 19, 2009) for 2,3,3,3 - tetrafluoropropene (HFO - 1234yf) as an acceptable ODS substitute for use in MVAC , subject to specific use condi tions , in place of CFC - 12 and HFC - 134a and issued final approval in March 2011 as stated in Section I . HFC - 134a, which is not an ozone deplet ing substance but has a high global warming potential (100 year GWP = 1430), has largely replaced CFC - 12 in motor vehicle air conditioners. Substituting 2,3,3,3 - tetrafluoropropene (HFO - 1234yf) for HFC - 134a is environmentally beneficial as the global warming potential o f HFO 1234yf is much lower ( 100 year GWP = 4). EPA received a petition on May 7, 2010 , (with a follow up petition on November 16, 2010) from the Natural Resources Defense Council, the Institute for Governance & Sustainable Development, and the Environmenta l Investigation Agency (a non - governmental organization) asking EPA to remove HFC - 134a from the list of acceptable substitutes under the SNAP program for use in motor vehicle air conditioners. Under TSCA, EPA has performed a pre -manufacture review for 2 ,3,3,3 - tetrafluoropropene (HFO - 1234yf) (75 FR 65987, Oct. 27, 2010). B ased on toxicity test ing data submitted as part of the pre manufacture notice for HFO - 1234yf, EPA identified health concerns for developmental toxicity and lethality to workers and consumers if they were exposed to a significant amount of HFO - 1234yf via inhalation. As a result, EPA has requested additional toxicity testing and issued a***E.O. 12866 Review

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Page 20 of 29 SNUR for 2,3,3,3 - tetrafluoropropene (HFO - 1234yf) . The SNUR requires manufacturers or other affected par ties to submit a notice ( a Significant New Use Notice, or SNUN) to EPA at least 90 days before the manufacture, import, or processing of HFO - 1234yf for the following uses: a) use other than as a refrigerant in MVAC systems in new passenger cars and vehicle s; b) commercial use other than in new passenger cars and vehicles in which the charging of MVAC systems with HFO - 1234yf was done by the motor vehicle original equipment manufacturer (OEM); and c) distribution in commerce of products intended for use by a consumer for the purpose of servicing, maintenance and disposal involving HFO - 1234yf . By issuing this SNUR, the Agency will: a) receive a SNUN of any person's intent to manufacture, import, or process the chemical substance for the described significant n ew use before that activity begins; b) have an opportunity to review and evaluate data submitted with a SNUN before the notice submitter begins manufacturing, importing, or processing a listed chemical substance for the described significant new use; and c ) be able to regulate prospective manufacture, import, or processing of a listed chemical substance before the described significant new use of that chemical substance occurs, if warranted. In issuing the SNUR, EPA did not raise concerns about potential exposures due to the use of HFO - 1234yf in MVAC as approved under the SNAP program , as the use restrictions under SNAP are expected to***E.O. 12866 Review

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Page 21 of 29 minimize environmental release and exposures . Other potential applications that may lead to significant exposures would trigger a SNUN and would likely trigger further review under SNAP. EPA believes these processes will provide adequate opportunity to address any health effects issues associated with possible increased use of HFO 1234yf which might result from a VOC exemption. In summary, for both trans - 1,3,3,3 - tetrafluoropropene (HFO 1234ze) and 2,3,3,3 - tetrafluoropropene (HFO - 1234yf), EPA believes that a) these chemicals qualify as negligibly reactive with respect to their contribution to tropospheric ozone format ion , and b) any non - tropospheric ozone related risks associated with potential increased use are adequately addressed by other existing programs and policies. We invite the public to submit comments and additional information relevant to the issue of these compounds’ overall risks to human health and the environment, and on whether such information should be considered in connection with the decision to grant an exemption from the regulatory definition of VOC. **I V**  **. Proposed Action** EPA is responding to th e petitions by proposing to revise its definition of VOC at 40 CFR 51.100(s) to add trans - 1,3,3,3 - tetrafluoropropene and 2,3,3,3 - tetrafluoropropene to the list of compounds that are exempt from the regulatory definition of VOC***E.O. 12866 Review

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Page 22 of 29 because they are negligibly reactive on the basis that they are less reactive than ethane on a mass MIR basis. **V. Statutory and Executive Order Reviews** A. Executive Order 12866: Regulatory Planning and Review and Executive Order 13563: Improving Regulat ion and Regulatory Review Under Executive Order (EO) 12866 (58 FR 51735, October 4, 1993), this action is treated as a significant regulatory action because some may view it as rais ing novel legal or policy issues arising out of legal mandates. Accordingl y, EPA submitted this action to the Office of Management and Budget (OMB) for review under EO 12866 and 13563 (76 FR 3821, January 21, 2011) 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 an information collection burden under the provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. Burden is defined at 5 CFR 1320.3(b). It does not contain any recordkeeping or reporting requirement. 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***E.O. 12866 Review

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Page 23 of 29 certifies that the proposed rule will not have a significant economic impact on a substantial number of small entities. Smal l entities include small businesses, small organizations, and small governmental jurisdictions. For purposes of assessing the impacts of this notice on small entities, small entity is defined as: (1) A small business that is a small industrial entity as de fined in the U.S. Small Business Administration (SBA) size standards. (See 13 CFR 121.); (2) A 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 smal l 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 this proposed rule on small entities, I certify that this action will not have a sign ificant economic impact on a substantial number of small entities. This proposed rule will not impose any requirements on small entities. We continue to be interested in the potential impacts of the proposed rule on small entities and welcome comments on issues related to such impacts. D. Unfunded Mandates Reform Act This action contains no federal mandates under the provisions of Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), 2 U.S.C.***E.O. 12866 Review

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Page 24 of 29 1531 - 1538 for state, local, or tribal governments or th e private sector . The action imposes no enforceable duty on any state, local or tribal governments, or the private sector. Therefore, this action is not subject to the requirements of sections 202 and 205 of the UMRA. This action is also not subject to th e requirements of section 203 of UMRA because it contains no regulatory requirements that might significantly or uniquely affect small governments. E. Executive Order 13132 - Federalism 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 action a ddresses the exemption of a set of chemical compounds from the VOC definition. Thus, Executive Order 13132 does not apply to this rule. In the spirit of Executive Order 13132, and consistent with EPA policy to promote communications between EPA and state a nd local governments, EPA specifically solicits comment on this proposed rule from state and local officials. F. Executive Order 13175: Consultation and Coordination with Indian Tribal Governments This action does not have tribal implications, as specified in Executive Order 13175 (65 FR 67249, November 9, 2000) . It will not***E.O. 12866 Review

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Page 25 of 29 have substantial direct effects on tribal governments, on the relationship between the federal government and Indian Tribes, or on the distribution of power and responsibilities between the federal government and Indian Tribes, as specified in Executive Order 13175. Thus, Executive Order 13175 does not apply to this rule. Although Executive Order 13175 does not apply to this proposed rule, EPA specifically solicits additional comment o n this proposed rule from tribal officials. G. Executive Order 13045: Protection of Children from Environmental Health and Safety Risks This action is not subject to EO 13045 (62 FR 19885, April 23, 1997) because it is not economically significant as defin ed in EO 12866. While this proposed rule is not subject to the Executive Order, EPA has reason to believe that ozone has a disproportionate effect on active children who play outdoors (62 FR 38856; 38859, July 18, 1997). EPA has not identified any specific studies on whether or to what extent these chemical compounds may affect children's health. EPA has placed the available data regarding the health effects of HFO - 1234yf in Docket No. EPA- HQ - OAR- 2003 - 0032 which is the docket for the SNUR for this compound. The public is invited to submit comments or identify peer reviewed studies and data, of which EPA may not be aware, that assess results of early life exposure to the chemical compounds herein.***E.O. 12866 Review

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Page 26 of 29 H. Executive Order 13211: Actions that Significantly Affect Energy Supply, Distribution, or Use This action is not a “significant energy action” as defined in Executive Order 13211, “Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, or Use” (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 proposes to revise EPA's definition of VOCs for purposes of preparing SIPs to attain the NAAQS for ozone under title I o f the CAA. I. National Technology Transfer and Advancement Act Section 12(d) of the National Technology Transfer and Advancement Act of 1995 ("NTTAA"), Public Law 104 - 113, section 12(d), (15 U.S.C. 272 note) directs EPA to use voluntary consensus standard s 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 practi ces) that are developed or adopted by voluntary consensus standards bodies. The NTTAA directs EPA to provide Congress, through OMB, explanations when the Agency decides not to use available and applicable voluntary consensus standards. This rulemaking does not involve technical***E.O. 12866 Review

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Page 27 of 29 standards. Therefore, EPA is not considering the use of any voluntary consensus standards. J. Executive Order 12898: Federal Actions to Address Environmental Justice in Minority Populat ions and Low - Income Populations Executive Orde r (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 missio n 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 proposed rule will not have disproportionately high and adverse human health or environmental effects on minority or low - income populations because it will not affect the level of protection provided to human health or the environment.***E.O. 12866 Review

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Page 28 of 29 P**age 2 8**  **of 29**  **- Air Quality: Revision to Definition of Volatile**  **Organic Compounds –**  **Exclusion of trans** **- 1,3,3,3**  **- tetrafluoropropene and**  **2,3,3,3 -**  **tetrafluoropropene** List of Subjects in 40 CFR Part 51 Environmental protection, Administrative practice and procedure, Air pollution control, Ozone, Reporting and recordkeeping requirements, Volatile organic compounds.

_________________________ Dated:

_________________________ Lisa P. Jackson, Administrator.***E.O. 12866 Review

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Page 29 of 29 For reasons set forth in the preamble, part 51 of chapter I of title 40 of the Code of Federal Regulations is proposed to be amended as follows: PART 51 - REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL OF IMPLEMENTATION PLANS. 1. The authority citation for Part 51, Subpart F, continues to read as follows: Authority: 42 U.S.C. 7401, 7411, 7412, 7413, 7414, 7470 - 7479, 7501 - 7508, 7601, and 7602. §51.100

– [Amended] 2. Section 51.100 is amended at the end of paragraph (s)(1) introductory text by remov ing the words “and perfluorocarbon compounds which fall into these classes:” and adding in their place a semi - colon and the words “; trans - 1,3,3,3 - tetrafluoropropene; 2,3,3,3 - tetrafluoropropene and perfluorocarbon compounds which fall into these classes:”.