Welcome to the State of California 

Indoor Radon Program   

The Indoor Radon Program, within the Environmental Management Branch, seeks to reduce the health risk from radon exposure by increasing awareness, identifying areas of high radon potential, and encouraging all Californians to test their homes for radon, fix their homes if they have a radon problem, and build new homes radon-resistant. Test. Fix. Save a Life.  

Radon Topics

Radon News

What is Radon?
How Radon Gets into Homes
Testing Your Home For Radon
Become A Certified Radon Service Provider
California Test Results
Radon Geologic Reports and Maps
Radon and Real Estate
Radon and Schools
Radon and Health Care Practitioners
Building Radon-Resistant
Radon and Water
Regulations and Standards
Contact Us


Radon News

Interactive California Radon Potential Map

The California Geological Survey has released an interactive web map providing radon potential information for areas of California with completed radon potential maps. Click here to go to the map. Downloadable GIS data for each study area can now be downloaded through the interactive map.


Special Report 232 - Radon Potential in Orange County, California The California Geological Survey has completed a radon potential study and report for Orange County, California. Click here to view all reports.



Aliso Canyon Gas Leak and radon Information                 



2015 County Winter Radon Survey - NOW CLOSED

All free test kits available During the 2015 Survey have been claimed.

Thank you to the many California residents who have participated. We have successfully distributed all test kits for this survey! All free test kit requests placed before Friday, April 1 will be honored.

Due to unforeseen postal delivery days, many test kits have not arrived to the lab on time and could not be tested. If your test kit results were affected by USPS delivery delays, you are still eligible to receive a replacement by calling Alpha Energy Labs at 1-800-324-5928. CDPH is currently inquiring with the US Postal Service on the reasons for the delays. If your test was affected, we sincerely apologize for the unforeseeable inconvenience.

 Test results will be sent to you approximately 3 weeks after you  return the test. You can also Check your test results here once they are available.  

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Last modified on: 8/2/2016 12:05 PM