Radon levels in Maine: Moderate
The model predicts a population-weighted basement average of 2.2 pCi/L across Maine's 16 counties - about 1.2× the US average of 1.8 pCi/L. Above-ground floors average 1.2 pCi/L.
Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. How the numbers work.
12 / 16
EPA Zone 1 counties (75%)
4 / 0
Zone 2 / Zone 3 counties
0
counties predicted ≥ 4 pCi/L
0%
of ZIP codes predicted ≥ 4 pCi/L
Maine counties by predicted radon
Sorted highest to lowest predicted basement average. 16 counties.
| County | Predicted basement | Upstairs | Grade | EPA zone | ZIPs |
|---|---|---|---|---|---|
| Oxford County | 2.6 pCi/L | 1.6 | Moderate | EPA Zone 1 | 29 |
| York County | 2.5 pCi/L | 1.6 | Moderate | EPA Zone 1 | 32 |
| Franklin County | 2.4 pCi/L | 1.4 | Moderate | EPA Zone 1 | 13 |
| Cumberland County | 2.3 pCi/L | 1.5 | Moderate | EPA Zone 1 | 36 |
| Knox County | 2.3 pCi/L | 1.4 | Moderate | EPA Zone 2 | 18 |
| Hancock County | 2.2 pCi/L | 1.3 | Moderate | EPA Zone 1 | 37 |
| Aroostook County | 2.2 pCi/L | 1.1 | Moderate | EPA Zone 1 | 40 |
| Waldo County | 2.1 pCi/L | 1.3 | Moderate | EPA Zone 2 | 18 |
| Androscoggin County | 1.9 pCi/L | 0.9 | Low | EPA Zone 1 | 14 |
| Kennebec County | 1.9 pCi/L | 0.9 | Low | EPA Zone 1 | 23 |
| Lincoln County | 1.9 pCi/L | 0.9 | Low | EPA Zone 1 | 24 |
| Somerset County | 1.9 pCi/L | 1.0 | Low | EPA Zone 1 | 23 |
| Piscataquis County | 1.9 pCi/L | 1.0 | Low | EPA Zone 1 | 11 |
| Washington County | 1.9 pCi/L | 0.9 | Low | EPA Zone 2 | 31 |
| Sagadahoc County | 1.8 pCi/L | 0.8 | Low | EPA Zone 2 | 8 |
| Penobscot County | 1.7 pCi/L | 0.8 | Low | EPA Zone 1 | 39 |
Maine radon questions
- Is radon high in Maine?
- Maine's population-weighted predicted basement average is 2.2 pCi/L, about 1.2× the US average of 1.8. 0 of its 16 modeled counties are predicted at or above the EPA action level of 4 pCi/L, 8 are in the 2-4 "consider fixing" range and 8 are below 2. 0% of Maine ZIP codes are predicted at 4 or higher.
- Which Maine county has the highest radon?
- Oxford County has the highest predicted basement average in Maine at 2.6 pCi/L (EPA Zone 1). The lowest is Penobscot County at 1.7 pCi/L. These are modeled area averages; individual homes in any county can test far higher.
- How many EPA Zone 1 counties are in Maine?
- 12 of Maine's 16 counties (75%) are EPA Zone 1 (highest potential), 4 are Zone 2 and 0 are Zone 3. The EPA zone map dates from 1993; the predicted values on this page come from a 2001-2021 model built on millions of actual tests, so the two can disagree for a given county.
- Should I test for radon in Maine?
- Yes - with some urgency. Maine's predicted average is in the moderate range, and 54% of its ZIP codes are predicted at 2 pCi/L or higher. A short-term charcoal kit or a continuous digital monitor will tell you your actual level within days.
Maine radon program
Many states offer free or discounted test kits and keep lists of certified mitigators. Find the Maine radon office through the EPA state radon contacts page. Then read how to test and what mitigation costs.