US Radon Risk Map by County
Tap any county for its EPA Radon Zone, or find your area below. Radon is a natural, radioactive gas and the second-leading cause of lung cancer — the EPA recommends every home be tested regardless of zone.
How to read this map
The EPA assigns each US county to one of three radon zones based on predicted average indoor radon levels. Zone 1 counties have a predicted average above 4 pCi/L (the EPA action level), Zone 2 from 2–4 pCi/L, and Zone 3 below 2 pCi/L. Zones describe the county average — individual homes vary widely, so the EPA recommends testing every home, even in Zone 3.
Source: EPA Map of Radon Zones. See our methodology. Found an error? Let us know via our about page.