EPA has proposed approval of a State Implementation Plan (SIP) revision, submitted by the Ohio EPA on December 19, 2016, to remove gasoline volatility standards in the Cincinnati and Dayton areas. The proposed revision removes the 7.8 psi low Reid Vapor Pressure (RVP) fuel requirements for the Cincinnati and Dayton areas as a component of the Ohio ozone SIP. In 2004, EPA had designated Butler, Clark, Clermont, Clinton, Greene, Miami, Montgomery, Hamilton and Warren counties as nonattainment for the 8-hour ozone standard. If approved, Ohio would revert to the federal 9.0 psi RVP requirement.
While higher RVP gasoline is often necessary in the winter for starting engines in cold weather, in summer, evaporative emissions from gasoline can contribute to increased ground-level ozone levels . At the same time, special low RVP blends of gasoline are more expensive to consumers and no longer have as substantial of an environmental benefit because of generally improved blends of gasoline and improved evaporative emissions control systems in automobiles.