The U.S. Environmental Protection Agency (EPA) has set limits on the amounts of certain pollutants that can safely be in our air. These limits are called the National Ambient Air Quality Standards (NAAQS).

EPA considers any geographic area that meets or has pollutant levels below the NAAQS to be an attainment area. An area with persistent air quality problems is designated a nonattainment area. This means that the area has violated federal health-based standards for outdoor air pollution. Each nonattainment area is declared for a specific pollutant. Nonattainment areas for different pollutants may overlap or share common boundaries.

Failure to act on nonattainment status can result in a potential loss of federal highway funding for areas in nonattainment. If an area exceeds EPA's NAAQS for ground level ozone or fine particulate matter (see also the fugitive dust section), local governments may be directly affected or have specific responsibilities such as implementing an emissions testing program.

When a project has the potential to contribute to poor air quality either directly (from facility emissions) or indirectly (from traffic) to air quality, your community should understand those impacts for strategic planning.

For areas with populations over 350,000, DEQ publishes an Air Quality Index at least once per day on its Web site. DEQ publishes this information for certain areas with lower populations as well.