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Counties with the Highest Radon Potential in Indiana

The top 25 of 92 Indiana 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
1Brown County
2
2Clay County
2
3Crawford County
2
4Daviess County
2
5Dearborn County
2
6Dubois County
2
7Floyd County
2
8Franklin County
2
9Gibson County
2
10Greene County
2
11Jackson County
2
12Jasper County
2
13Jefferson County
2
14Knox County
2
15Lake County
2
16LaPorte County
2
17Martin County
2
18Morgan County
2
19Newton County
2
20Ohio County
2
21Owen County
2
22Parke County
2
23Perry County
2
24Pike County
2
25Porter County
2

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 Indiana”, https://gismap.land/rankings/indiana/highest-radon-counties. Figures from EPA Map of Radon Zones (September 2025).

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