U.S. EPA classifies areas based on the National Ambient Air Quality Standards (NAAQS) that were initiated as a result of the Clean Air Act Amendments of 1990. For any given area nationwide, the air quality is monitored on an hourly basis for ground-level ozone, better known as smog. Ozone levels that exceed the NAAQS for a metropolitan statistical area (population more than 100,000) are categorized into one of five nonattainment levels: marginal; moderate; serious; severe; or extreme. Individual states are then required to initiate basic emissions testing in any nonattainment area ranked moderate and above.
On April 15, 2004, U.S. EPA announced that 33 Ohio counties were out of attainment for the eight-hour ozone standard. In order for Ohio to meet the eight-hour standard, additional air pollution control measures may be necessary in these counties.
Under the new eight-hour ozone standard, the following counties in the Cleveland and Akron area are required to continue the E-Check program: Cuyahoga; Geauga; Lake; Lorain; Medina; Portage; and Summit counties.