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Washington Uses Test Data and Geology Mapping to Inform the Public about Radon Potential

by Margaret Henderson

The Washington State Department of Health publishes test results on its Washington Tracking Network, with results updated to 2017, making radon test results from 1989-2017 available. Statewide, in 2017 a total of 2669 test results revealed that 24.8% were above 4 pCi/L, the USEPA recommended action level. The Department attributes radon as being the single largest source of radiation for almost everyone in Washington.

In order to promote testing and mitigation, the Washington Tracking Network provides mapping of test results, which includes a geology layer that shows characteristics of the surface geology as they relate to the potential for radon exposure.

* The rank of “high potential” is applied when the geology contains uranium or rocks that contain uranium. In Washington, uranium deposits are present in some parts of the state. Commercial mining also took place, ceased production and entered into reclamation.

* The “medium potential” applies when the local geology may have uranium containing rock deposited from glacial and other events such as the Missoula Floods (13,000-15,000 years ago) that brought uranium rich rocks into the area.

* A “low potential” exists when the soil is unlikely to contain uranium.

The Washington State Department of Natural Resources classified 57,000 identifiable rock and soil areas to place them into categories of potential for producing radon in order to create the geology map layer.

By providing the geology layer for the mapping, finer detail and explanation of radon potential is illustrated for the public. Along with test data (county, census tract and state level) and the geology layer, residents are given a better explanation of radon potential in Washington.

For more information, contact: Tina Echeverria tina.echeverria@doh.wa.gov