This action revises EPA's definition of volatile organic compounds (VOC) for purposes of preparing State implementation plans (SIPs) to attain the national ambient air quality standards (NAAQS) for ozone under title I of the Clean Air Act (CAA). This revision would add four compounds 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. This revision will modify the definition of VOC to say that: 1,1,1,2,2,3,3-heptafluoro-3-methoxy-propane (n- C<INF>3</INF>F<INF>7</INF>OCH<INF>3</INF>) (known as HFE-7000); 3- ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-(trifluoromethyl) hexane (known as HFE-7500, HFE-s702, T-7145, and L-15381); 1,1,1,2,3,3,3- heptafluoropropane (known as HFC 227ea); and methyl formate (HCOOCH<INF>3</INF>) will be considered to be negligibly reactive. If you use or produce any of these four compounds and are subject to EPA regulations limiting the use of VOCs in your product, limiting the VOC emissions from your facility, or otherwise controlling your use of VOCs, then you will not count these four compounds as a VOC in determining whether you meet these regulatory obligations. This action may also affect whether these four compounds are considered to be VOCs for State regulatory purposes, depending on whether the State relies on EPA's definition of VOC. As a result, if States and States' industries are subject to certain Federal regulations limiting emissions of VOCs, i.e., emissions of 1,1,1,2,2,3,3-heptafluoro-3-methoxy-propane, or 3- ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-(trifluoromethyl) hexane, or 1,1,1,2,3,3,3-heptafluoropropane, or methyl formate, these emissions may not be regulated for some purposes according to the rules governing States' enforceability of the measures. With this action, EPA is not finalizing a decision on how the Agency will evaluate future VOC exemption petitions. Currently, EPA is in the process of assessin