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Radon zones in Maine

The EPA assigns every county in Maine to one of three radon potential zones. 12 are in Zone 1, the highest category, home to about 89% of the state's residents.

16
Counties
12
Zone 1 counties
Predicted average above 4 pCi/L
4
Zone 2 counties
Predicted average 2-4 pCi/L
0
Zone 3 counties
Predicted average below 2 pCi/L

The map

Radon potential across Maine

Every county in Maine, filled by the zone the EPA assigns it. Zones follow geology rather than county lines, so the colour usually changes where the bedrock does, not where the border is.

Zone 1 · 12Zone 2 · 4Zone 3 · 0

Hover a county · click to open it

County by county

All 16 Maine counties

Zone 1 · > 4 pCi/LZone 2 · 2 - 4 pCi/LZone 3 · < 2 pCi/L
CountyZonePopulationCOPDSmokingLung ca. deaths
Androscoggin County1114k8.9%16.3%40.8
Aroostook County167k11.0%17.9%42.3
Cumberland County1310k6.1%10.9%31.9
Franklin County131k9.2%15.6%36.4
Hancock County157k8.3%13.3%32.2
Kennebec County1127k8.9%15.4%43.2
Lincoln County137k8.6%12.7%39.9
Oxford County160k10.7%17.8%41.2
Penobscot County1155k8.6%15.6%42.0
Piscataquis County117k11.2%18.0%48.3
Somerset County151k11.3%19.7%56.1
York County1219k7.8%13.4%36.5
Knox County241k8.6%13.6%29.6
Sagadahoc County238k8.1%13.9%31.5
Waldo County241k8.9%15.4%36.8
Washington County232k11.3%18.3%49.1

Zones from the EPA Map of Radon Zones. COPD and smoking are CDC PLACES model-based estimates of adult prevalence. Lung cancer death rates are age-adjusted deaths per 100,000 per year, 2019-2023, from NCI State Cancer Profiles. A dash means the source does not report a value for that county.

Highest potential

Zone 1 counties in Maine

These 12 counties have a predicted average indoor radon screening level above the EPA action level. The EPA recommends every home in them be tested.

Other states

Radon zones elsewhere