| California Nonattainment Areas for Ozone Pollution, as Designated by EPA on 4/15/2004 | |||
| Nonattainment Area Name | Counties | EPA Ozone Classification | Maximum Attainment Date (from 6/15/2004) |
| Los Angeles South Coast Air Basin, CA | Los Angeles (P) | Severe-17 | June 1, 2021 |
| Orange | |||
| Riverside (P) | |||
| San Bernardino (P) | |||
| Riverside Co, CA (Coachella Valley) | Riverside (P) | Serious | June 1, 2013 |
| San Joaquin Valley, CA | Fresno | Serious | June 1, 2013 |
| Kern (P) | |||
| Kings | |||
| Madera | |||
| Merced | |||
| San Joaquin | |||
| Stanislaus | |||
| Tulare | |||
| Amador and Calavaras Cos (Central Mountain Counties), CA | Amador | Basic | June 1, 2009 |
| Calaveras | |||
| Mariposa and Tuolumne Cos (Southern Mountain Counties), CA | Tuolumne | Basic | June 1, 2009 |
| Mariposa | |||
| Sacramento Metro, CA | El Dorado (P) | Serious | June 1, 2013 |
| Placer (P) | |||
| Sacramento | |||
| Solano (P) | |||
| Sutter (P) | |||
| Yolo | |||
| Nevada (Western Part), CA | Nevada (P) | Basic | June 1, 2009 |
| Los Angeles-San Bernardino Cos (W Mojave Desert), CA | San Bernardino (P) | Moderate | June 1, 2010 |
| Los Angeles (P) | |||
| Ventura Co, CA | Ventura (P) | Moderate | June 1, 2010 |
| Kern Co (Eastern Kern), CA | Kern (P) | Basic | June 1, 2009 |
| San Diego, CA | San Diego (P) | Basic | June 1, 2009 |
| Imperial Co, CA | Imperial | Marginal | June 1, 2007 |
| Chico, CA | Butte | Basic | June 1, 2009 |
| San Francisco Bay Area, CA | Alameda | Marginal | June 1, 2007 |
| Contra Costa | |||
| Marin | |||
| Napa | |||
| San Francisco | |||
| Santa Clara | |||
| San Mateo | |||
| Solano (P) | |||
| Sonoma (P) | |||
| Sutter County (Sutter Buttes), CA | Sutter (P) | Basic | June 1, 2009 |
| P = Partial County Designation | |||
| Source: California Institute for Federal Policy Research. http://www.calinst.org . Data Source: U.S. Environmental Protection Agency, April 15, 2004. | |||
