EPA has proposed to revise the definition of volatile organic compounds (VOCs) for the purposes of preparing State implementation plans (SIPs) to attain national ambient air quality standards (NAAQS) for ozone.  The revision would add 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.  The compounds proposed for addition to the list are propylene carbonate and dimethyl carbonate.

While not required by this proposal, EPA encourages States to continue tracking these compounds for photochemical modeling.   EPA also has requested comments on tracking the uses and emissions of these compounds, as well as more reactive compounds for which propylene carbonate and dimethyl carbonate may substitute.