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Washington Tracking Network Includes Geology Layer With Radon Data Mapping

by Margaret Henderson

The Washington State Department of Health website provides the Washington Tracking Network (WTN), A Source for Environmental Public Health Data, that includes radon data and allows selection of geology as a map layer. Test results from 1989-2016 are provided and can be viewed as “number of houses tested” or “test results.” An additional map layer may be added to show geology statewide, or by county or census tract. The geology layer is another means to encourage testing each residence, even though test results in the area may not have elevated radon levels.

The geology layer indicates the surface geology and the potential for radon exposures to be high, medium or low. The levels, which categorized 57,000 identifiable rock and soil types, are defined as:

  • High - geology contains uranium, or has rock types known to contain uranium.
  • Medium - (variable), geology may have uranium containing rock deposited from glacial or other events.
  • Low - geology or soil type unlikely to contain uranium.

The department notes that radon can be present anywhere despite the categorizations.

The information is based on US Geologic Survey (USGS) information. The Division of Geology and Earth Resources at the Washington State Department of Natural Resources evaluated surface geology based on standards established by USGS. Even though subsurface geology has low radon risk associated, surface rocks deposited by the Missoula Floods (13000-15,000 years ago) brought rocks with high uranium content into the state.

The geology layer underlies the radon data layer and may be viewed by moving the “transparency slider” up or down to give an indication of radon potential.

For more information, contact:

Washington Tracking Network, Washington State Department of Health. Web. "Geologic Risk Areas." Data obtained from the Division of Geology and Earth Resources, Department of Natural Resources. Published: 27 December 2015.