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Interactive California Radon Potential Map

by Margaret Henderson

The California Geological Survey has released an interactive map that provides information on radon potential in areas of California where the Survey has completed radon potential maps. See the map at http://maps.conservation.ca.gov/cgs/radon/
The map was produced in cooperation with the California Department of Public Health Radon Program. The map is intended to guide residents in understanding where radon may be found in excess of the USEPA recommended action level of 4 pCi/L; however, testing is recommended in all areas. Geographic Information System (GIS) data for each study area can now be downloaded through the interactive map.

The user may search for data by entering the location name, or by clicking on the map. In those areas where the radon potential mapping has been completed, results are provided. A pop-up block gives the information such as:
Potential: High
Description: 20 to 49.9 percent of home indoor-radon measurements are likely to exceed the U.S. EPA recommended action level of 4 picocuries per liter

Links are provided to the report from which data is derived and downloadable GIS data, such as:
CGS Report: SR 208
GIS Data: Download Data
Metadata: GIS Metadata

Base maps may be selected (satellite or other) and the application tools allow for further interaction. For tabular results by zip code area, a file link is provided:

For more information, contact:
California Department of Public Health
Toll-Free California Radon Hotline: 1-800-745-7236
Phone: 916- 449-5674
Fax: 916-449-5665
Email: Radonprogram@cdph.ca.gov