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Counties with the Highest Radon Potential in Maine

The top 16 of 16 Maine 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
1Knox County
2
2Sagadahoc County
2
3Waldo County
2
4Washington County
2
5Androscoggin County
1
6Aroostook County
1
7Cumberland County
1
8Franklin County
1
9Hancock County
1
10Kennebec County
1
11Lincoln County
1
12Oxford County
1
13Penobscot County
1
14Piscataquis County
1
15Somerset County
1
16York 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 Maine”, https://gismap.land/rankings/maine/highest-radon-counties. Figures from EPA Map of Radon Zones (September 2025).

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