This polygon shapefile displays federal Nitrogen Oxide (NO2), Sulfur Dioxide (SO2), and Carbon Monoxide (CO) area designations contained in 40CFR81.305, the federal National Ambient Air Quality Standard (NAAQS) which monitors each pollutant as per the Clean Air Act. There are three designation categories: nonattainment, unclassifiable and attainment areas. Non-attainment areas are those which are in violation of the standard. This data layer is current as of November 2003. Projection: Teale Albers, NAD83.This shapefile can be used to identify designation areas that are defined pursuant to the corresponding federal national ambient air quality standard for each pollutant as per the Clean Air Act.