National Ambient Air Quality Standards (NAAQS) Monitoring and Compliance

States have the responsibility of collecting and submitting air quality monitoring data to the EPA to demonstrate compliance with air quality standards. To fulfill this responsibility, states operate a monitoring network for measuring, and recording the ambient concentrations of criteria pollutants. This data is then submitted to the EPA, who verifies that a state is in compliance. Compliance is determined by examining three years of air quality data, and designating areas of a State (usually by county) as being in attainment, nonattainment, or maintenance, these air quality terms are defined below.

  • Attainment Areas: Where the measured concentrations of pollutants are less than or equal to the NAAQS.
  • Nonattainment Areas: Where the measured concentrations of pollutants are greater than, or exceed, the NAAQS.
  • Maintenance: An area previously in nonattainment which is now in attainment of the NAAQS. Additional requirements are applied to the area to ensure it remains in attainment.

It's important to note that states have the option of flagging data which they determine to be the result of an uncommon occurrence not likely to reoccur. When flagged, data is evaluated by the EPA and determined to be either omitted or included in the determination of whether the area meets the NAAQS. The Exceptional Events Rule dictates this process, the details of which are explained later in this module under the Exceptional Events Rule section.

NAAQS Nonattainment: NAAQS nonattainment status leads to more stringent pollution control and permitting requirements for sources within a nonattainment area. Prescribed burning activities in and around a nonattainment area could be subject to additional restrictions and controls, and are required to comply with additional regulations such as general conformity (described in a few pages).