Approval and Promulgation of Air Quality Implementation Plans; Ohio; Ohio PM2.5

The Environmental Protection Agency (EPA) is proposing to approve, under the Clean Air Act (CAA), revisions to Ohio's state implementation plan (SIP) as requested by the Ohio Environmental Protection Agency on June 19, 2014. The changes to the SIP include revisions related to particulate matter smaller than 2.5 micrometers (PM2.5) defining a significance level for PM2.5 for nonattainment areas, baseline for determining credit for emission offsets, location of offsetting emissions in nonattainment areas, and offset requirements. The revisions also include establishing definitions for emergency, emergency engine, publicly owned treatment works, and semi- public disposal system and incorporating minor organizational or typographical changes.