As Ohio continues to pursue attainment with the 2008 ozone standard, EPA has moved to further reduce ozone. In 2008, EPA adopted a standard of 75 ppb for ozone. Under this standard, Ohio classified the Cleveland, Columbus, and Cincinnati areas as being in “marginal” nonattainment. On January 28, 2016, Ohio proposed to redesignate the Cincinnati area as being in attainment with the 2008 standard. The proposed redesignation request covers Butler, Clermont, Clinton, Hamilton and Warren counties. According to information from the U.S. EPA Air Quality System, ozone levels trended downward for 2012-2015, with the region hitting 75 ppb or lower on average at all monitoring locations in 2014. On April 11, 2016, EPA issued a final rule giving the Cleveland area a one-year extension to achieve attainment. This extension allows Ohio to use 2013-2015 monitoring data as opposed to 2012-2015 data for the Cleveland area and could allow the area to move from marginal nonattainment to attainment for the 2008 standard.

However, the area will still have to meet the more stringent 2015 standard of 70 ppb for ozone. Within a year, Ohio must recommend designations of attainment, nonattainment, or unclassifiable under the 2015 8-hour ozone standard for all areas of the state. Given the downward trend in ozone levels, Ohio will not likely have to take dramatic action such as expanding the E-Check program (currently only implemented in the Cleveland area) to meet the new standard. EPA is expected to make final designations in 2017.