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Radon zones in Massachusetts

The EPA assigns every county in Massachusetts to one of three radon potential zones. 3 are in Zone 1, the highest category, home to about 47% of the state's residents.

14
Counties
3
Zone 1 counties
Predicted average above 4 pCi/L
10
Zone 2 counties
Predicted average 2-4 pCi/L
1
Zone 3 counties
Predicted average below 2 pCi/L

The map

Radon potential across Massachusetts

Every county in Massachusetts, 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 · 3Zone 2 · 10Zone 3 · 1

Hover a county · click to open it

County by county

All 14 Massachusetts counties

Zone 1 · > 4 pCi/LZone 2 · 2 - 4 pCi/LZone 3 · < 2 pCi/L
CountyZonePopulationCOPDSmokingLung ca. deaths
Essex County1810k6.3%11.4%29.1
Middlesex County11.6M4.6%9.1%26.1
Worcester County1867k6.3%12.3%32.1
Barnstable County2232k7.3%10.5%27.4
Berkshire County2127k7.7%12.7%29.9
Bristol County2582k7.6%15.8%38.0
Dukes County221k6.8%10.8%15.9
Franklin County271k7.7%12.8%32.2
Hampden County2460k7.7%14.8%34.5
Hampshire County2163k5.6%9.7%27.2
Nantucket County214k4.6%9.1% -
Norfolk County2727k4.9%9.2%28.2
Plymouth County2535k6.4%11.9%31.0
Suffolk County3768k5.1%11.1%26.3

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 Massachusetts

These 3 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