The federal Clean Air Act (CAA) requires the U.S. Environmental Protection Agency (EPA) to establish health-based national ambient air quality standards (NAAQS), designate nonattainment areas, and promulgate planning requirements, for six criteria pollutants. Similarly, the state establishes California Ambient Air Quality Standards (CAAQS), which require incremental progress towards attainment. Over the years, the District and CARB have adopted numerous State Implementation Plans (SIPs) to attain the NAAQS, which serve as the primary vehicles for improving air quality in the San Joaquin Valley. Each SIP builds upon the work of prior plans, while establishing the path for continued air quality improvements. Following the adoption of each attainment plan, the District implements plan strategies through regulatory development, outreach, continued research, and incentive programs. For additional information on San Joaquin Valley attainment plans, visit our Air Quality Plans webpage.
Units of measure for the standards described below are parts per million (ppm) by volume, parts per billion (ppb) by volume, and micrograms per cubic meter of air (µg/m3).
| Pollutant | Designation/Classification | |
|---|---|---|
| Federal Standardsa | State Standardsb | |
| Ozone - One hour | Revokedf | Nonattainment/Severe |
| Ozone - Eight hour | Nonattainment/Extremee | Nonattainment |
| PM 10 | Attainmentc | Nonattainment |
| PM 2.5 | Nonattainmentd | Nonattainment |
| Carbon Monoxide | Attainment/Unclassified | Attainment/Unclassified |
| Nitrogen Dioxide | Attainment/Unclassified | Attainment |
| Sulfur Dioxide | Attainment/Unclassified | Attainment |
| Lead (Particulate) | No Designation/Classification | Attainment |
| Hydrogen Sulfide | No Federal Standard | Unclassified |
| Sulfates | No Federal Standard | Attainment |
| Visibility Reducing Particles | No Federal Standard | Unclassified |
| Vinyl Chloride | No Federal Standard | Attainment |
| Pollutant | Averaging Time | Concentration |
|---|---|---|
| Ozone | 8 Hour (1997) | 0.08 ppm |
| 8 Hour (2008) | 0.075 ppm | |
| 8 Hour (2015) | 0.07 ppm | |
| 1 Hour (1979) | (revoked) | |
| Carbon Monoxide | 8 Hour | 9 ppm |
| 1 Hour | 35 ppm | |
| Nitrogen Dioxide | 1-hour | 100 ppb |
| Annual | 53 ppb | |
| Sulfur Dioxide | 1-hour | 75 ppb |
| 3-hour | 0.5 ppm | |
| PM 10 | Annual | (revoked) |
| 24 Hour | 150 µg/m3 | |
| PM 2.5 (1997 Standard) | Annual | 15 µg/m3 |
| 24 Hour | 65 µg/m3 | |
| PM 2.5 (2006 Standard) | Annual | 15 µg/m3 |
| 24 Hour | 35 µg/m3 | |
| PM 2.5 (2012 Standard) | Annual | 12 µg/m3 |
| 24 Hour | 35 µg/m3 | |
| Lead | Rolling three-month period, evaluated over a three-year period | 0.15 µg/m3 |
a See https://www.epa.gov/criteria-air-pollutants/naaqs-table
| Pollutant | Averaging Time | Concentration |
|---|---|---|
| Ozone | 8 Hour | 0.070 ppm (137 µg/m3) |
| 1 Hour | 0.09 ppm (180 µg/m3) | |
| Carbon Monoxide | 8 Hour | 9 ppm (10 mg/m3) |
| 1 Hour | 20 ppm (23 mg/m3) | |
| Nitrogen Dioxide | Annual Arithmetic Mean | 0.030 ppm (57 µg/m3) |
| 1 Hour | 0.18 ppm (339 µg/m3) | |
| Sulfur Dioxide | ||
| 24 Hour | 0.04 ppm (105 µg/m3) | |
| 1 Hour | 0.25 ppm (655 µg/m3) | |
| PM 10 | Annual Arithmetic Mean | 20 µg/m3 |
| 24 Hour | 50 µg/m3 | |
| PM 2.5 | Annual Arithmetic Mean | 12 µg/m3 |
| 24 Hour | none | |
| Sulfates | 24 Hour | 25 µg/m3 |
| Lead | ||
| 30 Day Average | 1.5 µg/m3 | |
| Hydrogen Sulfide | 1 Hour | 0.03 ppm (42 µg/m3) |
| Vinyl Chloride (chloroethene) | 24 Hour | 0.010 ppm (26 µg/m3) |
| Visibility Reducing particles | 8 Hour | (see belowb) |
a See http://www.arb.ca.gov/research/aaqs/aaqs2.pdf
b In 1989, CARB converted both the general statewide 10-mile visibility standard and the Lake Tahoe 30-mile visibility standard to instrumental equivalents, which are "extinction of 0.23 per kilometer" and "extinction of 0.07 per kilometer" for the statewide and Lake Tahoe Air Basin standards, respectively.
