The Iowa Radon Survey has indicated that Iowa has the largest percentage (or 71.6%) of homes above the US Environmental Protection Agency action level of 4pCi/L. It is also designated by the US EPA as an entirely zone 1 state, which means that at least 50% of the homes are above US EPA's recommended action level.
The data files below include radon tests conducted in private Iowa residences or during real estate transactions. They include test results conducted in houses with and without mitigation systems which met the criteria for a valid test. County data files show aggregate test data for each county. Zip code data files show aggregate test data for zip codes, but is not sorted by county. Please refer to the Radon Aggregate Data Field List and Descriptions document for more information about the files. To request other radon data sets for research purposes, please contact Angela Leek, Bureau Chief for the Bureau of Radiological Health at 515-281-3478.