8-Hour Ozone (2015) Nonattainment Areas
Data is current as of May 31, 2025
| EXTREME |
| Los Angeles-South Coast Air Basin, CA |
| San Joaquin Valley, CA |
| |
| SEVERE 15 |
| Los Angeles-San Bernardino Counties (West Mojave Desert), CA |
| Riverside County (Coachella Valley), CA |
| San Diego County, CA |
| |
| SERIOUS |
| Allegan County, MI |
| Baltimore, MD |
| Berrien County, MI |
| Chicago, IL-IN-WI |
| Cleveland, OH |
| Dallas-Fort Worth, TX |
| Denver Metro/North Front Range, CO |
| Greater Connecticut, CT |
| Houston-Galveston-Brazoria, TX |
| Kern County (Eastern Kern), CA |
| Las Vegas, NV |
| Milwaukee, WI |
| Morongo Band of Mission Indians, CA |
| Muskegon County, MI |
| Nevada County (Western part), CA |
| New York-Northern New Jersey-Long Island, NY-NJ-CT |
| Northern Wasatch Front, UT |
| Philadelphia-Wilmington-Atlantic City, PA-NJ-MD-DE |
| Sacramento Metro, CA |
| San Antonio, TX |
| Sheboygan County, WI |
| St. Louis, MO-IL |
| Ventura County, CA |
| |
| MODERATE |
| Louisville, KY-IN |
| Mariposa County, CA |
| Pechanga Band of Luiseno Mission Indians of the Pechanga Reservation, CA |
| Phoenix-Mesa, AZ |
| Uinta Basin, UT |
| Washington, DC-MD-VA |
| |
| MARGINAL |
| Amador County, CA |
| Butte County, CA |
| Calaveras County, CA |
| El Paso-Las Cruces, TX-NM |
| Imperial County, CA |
| San Francisco Bay Area, CA |
| San Luis Obispo (Eastern part), CA |
| Southern Wasatch Front, UT |
| Sutter Buttes, CA |
| Tuolumne County, CA |
| Yuma, AZ |
| |
| MARGINAL (RURAL TRANSPORT) |
| Tuscan Buttes, CA |
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