Nonattainment areas
Nonattainment means that a geographic area has not consistently met the clean air levels set by the U.S. Environmental Protection Agency in the National Ambient Air Quality Standards. Legal descriptions of these areas are available in Oregon Administrative Rules, Chapter 340, Division 204-0010.
Maintenance areas
Maintenance areas are those geographic areas that had a history of nonattainment, but are now consistently meeting the National Ambient Air Quality Standard. Maintenance areas have been re-designated by EPA from "nonattainment" to "attainment with a maintenance plan," or designated by the Environmental Quality Commission. Legal descriptions of these areas are listed in Oregon Administrative Rules,
Chapter 340, Division 204-0010.