Nonattainment Area
A geographic area that fails to meet one or more National Ambient Air Quality Standards for a criteria pollutant.
Detailed Explanation
A nonattainment area is any area that the EPA determines does not meet (or contributes to ambient air quality in a nearby area that does not meet) the national primary or secondary ambient air quality standards for a criteria pollutant. When an area is designated nonattainment, the state must develop a State Implementation Plan (SIP) describing how it will bring the area into attainment. This plan typically includes additional emission controls on industrial sources, tighter vehicle inspection programs, and transportation planning measures to reduce vehicle miles traveled. Nonattainment designations have significant regulatory and economic consequences — new or expanding industrial facilities in nonattainment areas face stricter permitting requirements, and federal highway and transit funding may be affected. The EPA classifies nonattainment areas by severity: marginal, moderate, serious, severe, and extreme for ozone; moderate and serious for PM2.5. As of 2024, dozens of US counties remain in nonattainment for ozone, PM2.5, or both. California's San Joaquin Valley has historically been one of the most severely affected regions, designated as "extreme" nonattainment for ozone. Cities in nonattainment areas tend to receive lower Air Quality Grades on AirHistory, as the designation reflects chronic pollution levels that exceed health-based standards.
Related Terms
National Ambient Air Quality Standards (NAAQS)
EPA-established limits on concentrations of six criteria pollutants that must be met nationwide to protect public health and the environment.
Clean Air Act
The primary federal law governing air quality in the United States, first enacted in 1963 and significantly amended in 1970 and 1990.
EPA Air Quality System (AQS)
The EPA's national database of ambient air quality data collected from monitoring stations across the United States.
Criteria Pollutants
The six common air pollutants regulated by the EPA under the Clean Air Act: ozone, PM2.5, PM10, CO, NO2, and SO2.
Frequently Asked Questions
A geographic area that fails to meet one or more National Ambient Air Quality Standards for a criteria pollutant.
A nonattainment area is any area that the EPA determines does not meet (or contributes to ambient air quality in a nearby area that does not meet) the national primary or secondary ambient air quality standards for a criteria pollutant. When an area is designated nonattainment, the state must develop a State Implementation Plan (SIP) describing how it will bring the area into attainment. This plan typically includes additional emission controls on industrial sources, tighter vehicle inspection programs, and transportation planning measures to reduce vehicle miles traveled.