Counties with the Highest Radon Potential in Pennsylvania
The top 25 of 67 Pennsylvania counties on GIS Map, ranked by EPA radon zone, where zone 1 carries the highest predicted indoor radon potential and zone 3 the lowest.
| # | County | EPA radon zone |
|---|---|---|
| 1 | Philadelphia County | 3 |
| 2 | Cambria County | 2 |
| 3 | Crawford County | 2 |
| 4 | Elk County | 2 |
| 5 | Erie County | 2 |
| 6 | Fayette County | 2 |
| 7 | Forest County | 2 |
| 8 | Greene County | 2 |
| 9 | Jefferson County | 2 |
| 10 | Lawrence County | 2 |
| 11 | McKean County | 2 |
| 12 | Mercer County | 2 |
| 13 | Pike County | 2 |
| 14 | Potter County | 2 |
| 15 | Somerset County | 2 |
| 16 | Warren County | 2 |
| 17 | Washington County | 2 |
| 18 | Wayne County | 2 |
| 19 | Adams County | 1 |
| 20 | Allegheny County | 1 |
| 21 | Armstrong County | 1 |
| 22 | Beaver County | 1 |
| 23 | Bedford County | 1 |
| 24 | Berks County | 1 |
| 25 | Blair 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 Pennsylvania”, https://gismap.land/rankings/pennsylvania/highest-radon-counties. Figures from EPA Map of Radon Zones (September 2025).
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