Radon zones in California
Zone 1: 2, Zone 2: 29, Zone 3: 27. A zone is an area estimate; EPA says all homes should be tested.
- Alameda County Zone 2
- Alpine County Zone 2
- Amador County Zone 2
- Butte County Zone 3
- Calaveras County Zone 2
- Colusa County Zone 3
- Contra Costa County Zone 2
- Del Norte County Zone 3
- El Dorado County Zone 2
- Fresno County Zone 2
- Glenn County Zone 3
- Humboldt County Zone 3
- Imperial County Zone 3
- Inyo County Zone 2
- Kern County Zone 2
- Kings County Zone 3
- Lake County Zone 3
- Lassen County Zone 3
- Los Angeles County Zone 2
- Madera County Zone 2
- Marin County Zone 3
- Mariposa County Zone 2
- Mendocino County Zone 3
- Merced County Zone 3
- Modoc County Zone 3
- Mono County Zone 2
- Monterey County Zone 2
- Napa County Zone 3
- Nevada County Zone 2
- Orange County Zone 3
- Placer County Zone 2
- Plumas County Zone 2
- Riverside County Zone 2
- Sacramento County Zone 3
- San Benito County Zone 2
- San Bernardino County Zone 2
- San Diego County Zone 3
- San Francisco County Zone 2
- San Joaquin County Zone 3
- San Luis Obispo County Zone 2
- San Mateo County Zone 2
- Santa Barbara County Zone 1
- Santa Clara County Zone 2
- Santa Cruz County Zone 2
- Shasta County Zone 3
- Sierra County Zone 2
- Siskiyou County Zone 3
- Solano County Zone 3
- Sonoma County Zone 3
- Stanislaus County Zone 3
- Sutter County Zone 3
- Tehama County Zone 3
- Trinity County Zone 3
- Tulare County Zone 2
- Tuolumne County Zone 2
- Ventura County Zone 1
- Yolo County Zone 3
- Yuba County Zone 2
County not listed? See what we left out and why. Leave your email to hear if this data changes.