The Environmental Protection Agency (EPA) is approving, under the Clean Air Act (CAA), revisions to Ohio's state implementation plan (SIP) as requested by the Ohio Environmental Protection Agency (OEPA) to EPA on June 19, 2014. The revisions to Ohio's SIP implement certain EPA regulations for particulate matter smaller than 2.5 micrometers (PM<INF>2.5</INF>) by establishing definitions related to PM<INF>2.5</INF>, defining PM<INF>2.5</INF> increment levels, and setting PM<INF>2.5</INF> class 1 variances. The revisions also incorporate changes made to definitions and regulations that recognize nitrogen oxides (NO<INF>X</INF>) as an ozone precursor, revising and adding definitions, adding Federal land manager notification requirements, and incorporating minor organizational or typographical changes.