Who is responsible for designating air quality areas?

The responsibility for designating air quality areas primarily lies with the states. This is due to the framework established by the Clean Air Act, which empowers state governments to develop state implementation plans (SIPs) that outline how they will achieve and maintain compliance with national air quality standards set by the federal government.

States collect data on air quality and assess their regions' specific needs and conditions. Based on this information, they can make informed decisions on designating areas as "attainment" (meeting air quality standards) or "non-attainment" (not meeting standards), as well as "maintenance" areas that are currently meeting standards but may have been previously designated as non-attainment.

While the Environmental Protection Agency (EPA) sets the national standards and provides guidance, it is the states that have the authority and responsibility to implement these regulations locally, which includes the designation of air quality areas based on their unique criteria and data. Local governments typically follow the lead of state regulations in this area, and the federal government does not directly designate these areas but sets the parameters within which states operate.