The USEPA is approving, in final, Ohio's 1990 base-year ozone precursor emissions inventories for the Canton, Cincinnati-Hamilton, Cleveland-Akron-Lorain and Youngstown-Warren-Sharon ozone nonattainment areas as revisions to the Ohio State Implementation Plan (SIP). The emissions inventories were submitted to satisfy a Federal requirement that States containing ozone nonattainment areas submit inventories of actual ozone precursor emissions for the year 1990. The Ohio ozone nonattainment areas covered by this rulemaking are Canton (Stark County); Cincinnati-Hamilton (Butler, Clermont, Hamilton and Warren Counties); Cleveland-Akron-Lorain (Ashtabula, Cuyahoga, Geauga, Lake, Lorain, Medina, Portage and Summit Counties); and Youngstown-Warren- Sharon (Mahoning and Trumbull Counties).