Radon zones in Maine
| Aroostook County | Maine | 1 |
| Cumberland County | Maine | 1 |
| Franklin County | Maine | 1 |
| Hancock County | Maine | 1 |
| Kennebec County | Maine | 1 |
| Knox County | Maine | 2 |
| Oxford County | Maine | 1 |
| Penobscot County | Maine | 1 |
| Piscataquis County | Maine | 1 |
| Somerset County | Maine | 1 |
| Waldo County | Maine | 2 |
| Washington County | Maine | 2 |
| York County | Maine | 1 |
Sources
- Maine: EPA Map of Radon Zones, US Environmental Protection Agency, checked 1 November 2026
- EPA Map of Radon Zones, US Environmental Protection Agency, checked 1 November 2026
- Maine: EPA Map of Radon Zones, US Environmental Protection Agency, checked 1 November 2026
- EPA Map of Radon Zones, US Environmental Protection Agency, checked 1 November 2026
- Maine: EPA Map of Radon Zones, US Environmental Protection Agency, checked 1 November 2026
- EPA Map of Radon Zones, US Environmental Protection Agency, checked 1 November 2026
- Maine: EPA Map of Radon Zones, US Environmental Protection Agency, checked 1 November 2026
- EPA Map of Radon Zones, US Environmental Protection Agency, checked 1 November 2026
- Maine: EPA Map of Radon Zones, US Environmental Protection Agency, checked 1 November 2026
- EPA Map of Radon Zones, US Environmental Protection Agency, checked 1 November 2026
- Maine: EPA Map of Radon Zones, US Environmental Protection Agency, checked 1 November 2026
- EPA Map of Radon Zones, US Environmental Protection Agency, checked 1 November 2026
"Secondary" marks a source used only because the official page could not be read.