Attainment Status of National Ambient Air Quality Standards
What are the NAAQS?
The Clean Air Act defines six principal pollutants as the Criteria Air Pollutants: carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO2), ground-level ozone (O3), particulate matter (PM2.5 and PM10), and sulfur dioxide (SO2).
The National Ambient Air Quality Standards (NAAQS) are set by the U.S. Environmental Protection Agency to protect public health and the environment. These standards set allowable levels of each criteria air pollutant in ambient (outdoor) air. The EPA periodically reviews the NAAQS and may revise them as provided in law.
Areas of the nation that meet the NAAQS are attainment areas, while areas that exceed one or more NAAQS are nonattainment areas. The EPA requires states to establish additional air quality planning measures to bring nonattainment areas into attainment.
Planning for the new PM2.5 standard
On February 7, 2024, EPA strengthened the annual primary (health-based) National Ambient Air Quality Standard for fine particulate matter (PM2.5) from 12.0 µg/m3 to 9.0 µg/m3. This change is being made after a review of the available scientific evidence, technical information, and advice of an independent scientific panel. EPA says lowering the standard will result in significant public health benefits, advance the economy and improve quality of life. Final designations will be completed by February 6, 2026. DAQ is preparing for this designation process.
North Carolina Attainment Status
Since 2015, all areas of North Carolina are in attainment with all federal NAAQS.
| Pollutant | Standard | Attainment | Nonattainment Counties |
|---|---|---|---|
| Ozone | 0.070 ppm 8-hour average (2015 standard) |  | None |
| Lead | 0.15 μg/m3 rolling 3-month average (2008 standard) | | None |
| Particulate Matter (PM2.5) | 12.0 μg/m3 1-year average (2012 standard) | | None |
| 15.0 μg/m3 1-year average (2012 standard) | | None | |
| 35 μg/m3 24-hour average (2012 standard) | | None | |
| Particulate Matter (PM10) | 150 μg/m3 24-hour average (2012 standard) | | None |
| Carbon Monoxide | 9 ppm 8-hour average (1971 standard) | | None |
| 35 ppm 1-hour average (1971 standard) | | None | |
| Nitrogen Dioxide | 100 ppb 1-hour standard (2010 standard) | | None |
| 53 ppb 1-year average (1971 standard) | | None | |
| Sulfur Dioxide | 75 ppb 1-hour average (2010 standard) | | None |
| 0.5 ppm 3-hour average (1971 standard) | | None |
Updated Aug. 2022
North Carolina Attainment History
North Carolina has made tremendous progress in recent decades toward improving air quality by reaching full attainment with all NAAQS across the entire state.
In the past, certain areas of North Carolina were designated nonattainment for ozone, PM2.5, carbon monoxide or sulfur dioxide. The below pages have information on those nonattainment designation and the State Implementation Plans that led to eventual attainment.
- Ozone Designation History
- Particulate Matter 2.5 Designation History
- Sulfur Dioxide Designation History
- Carbon Monoxide Designation History
Early Action Compact
Archived information about the North Carolina Early Action Compact efforts are available on this webpage.