WNC and Radon

North Carolina
The goal of this map is to help National, State, and local organizations to target their resources and to enforce radon-resistant building codes. This map is not designed to be used to decide whether a home in a given zone should be tested for radon. There have been homes found with elevated levels of radon, in all three zones. Every home should be tested, regardless of geographic location. The EPA notes that this map is not to be used in lieu of testing during real estate transactions.


This map was developed by using five factors to determine the radon potential: geology; soil permeability; aerial radioactivity; indoor radon measurements; and, foundation type. Radon potential estimate is based on the geologic provinces. Radon Index Matrix is the quantitative estimate of radon potential. Confidence Index Matrix shows the quantity and quality of the data used to assess the radon possibility. Geologic Provinces were adjusted to county boundaries for the Map of Radon Zones.

The EPA states, “Sections 307 and 309 of the Indoor Radon Abatement Act of 1988 (IRAA) directed EPA to list and identify areas of the U.S. with the potential for elevated indoor radon levels. EPA’s Map of Radon Zones assigns each of the 3,141 counties in the U.S. to one of the three zones based on radon potential:”