Close Menu


The United States Environmental Protection Agency (U.S. EPA) is required under the federal Clean Air Act (CAA) to designate (or classify) areas within two years of the promulgation of a new National Ambient Air Quality Standard (NAAQS). Each county within a state is designated or classified as attainment, nonattainment, or unclassifiable under NAAQS for each of the criteria pollutants. An area can be considered to be designated “attainment” for one criteria pollutant, and “nonattainment” for another. Prior to issuing designations, U.S. EPA solicits designation recommendations from the states and a 120 day consultation period is required prior to the issuance of final designations.