Indoor Radon Risk Levels in the Portland Metro Area
Level of radon risk for each zip code is based on the maximum result, the average of all results, and the percent of locations within the zip code with a result of 4 pCi/L or greater. Risk level was only given for zip codes with test results in 20 or more locations. Provisional Risk Level was assigned to zip codes with test results in 5-19 locations and should be interpreted more cautiously.
