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Counties with the Highest Radon Potential in Iowa

The top 25 of 99 Iowa counties on GIS Map, ranked by EPA radon zone, where zone 1 carries the highest predicted indoor radon potential and zone 3 the lowest.

#CountyEPA radon zone
1Adair County
1
2Adams County
1
3Allamakee County
1
4Appanoose County
1
5Audubon County
1
6Benton County
1
7Black Hawk County
1
8Boone County
1
9Bremer County
1
10Buchanan County
1
11Buena Vista County
1
12Butler County
1
13Calhoun County
1
14Carroll County
1
15Cass County
1
16Cedar County
1
17Cerro Gordo County
1
18Cherokee County
1
19Chickasaw County
1
20Clarke County
1
21Clay County
1
22Clayton County
1
23Clinton County
1
24Crawford County
1
25Dallas County
1

Source: EPA Map of Radon Zones (September 2025). All counties with data are ranked. Estimates carry margins of error.

Citing this page: GIS Map, “Counties with the Highest Radon Potential in Iowa”, https://gismap.land/rankings/iowa/highest-radon-counties. Figures from EPA Map of Radon Zones (September 2025).

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