Radon Levels in Massachusetts

14 counties — 3 high risk, 10 moderate, 1 low risk

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10
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Zone 1 High (21.4%) Zone 2 Moderate (71.4%) Zone 3 Low (7.1%)

Massachusetts Radon Zone Map

Counties colored by EPA radon zone. Red = Zone 1, Orange = Zone 2, Green = Zone 3.

Highest-Risk Counties

Essex39.4% above action level
Middlesex36.8% above action level
Worcester43.2% above action level

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All 14 Counties — By Radon Risk

CountyEPA ZoneTests% Above 4 pCi/L
Essex High 142 39.4%
Middlesex High 258 36.8%
Worcester High 146 43.2%
Barnstable Moderate 62 46.8%
Berkshire Moderate 34 29.4%
Bristol Moderate 114 37.7%
Dukes Moderate — —
Franklin Moderate 14 50%
Hampden Moderate 84 35.7%
Hampshire Moderate 30 33.3%
Nantucket Moderate — —
Norfolk Moderate 126 38.9%
Plymouth Moderate 98 50%
Suffolk Low 105 30.5%

Sources: EPA Map of Radon Zones, CDC Environmental Health Tracking Network

Frequently Asked Questions

How many counties in Massachusetts have high radon risk?

Massachusetts has 3 counties classified as EPA Zone 1 (high radon risk), 10 as Zone 2 (moderate), and 1 as Zone 3 (low risk).

Is radon a problem in Massachusetts?

Massachusetts has 3 high-risk counties where elevated radon is likely. The EPA recommends all homes in Massachusetts be tested for radon, regardless of which zone they're in.

How do I check radon levels for my Massachusetts address?

Enter your ZIP code in the search box above to see your county's EPA radon zone and available testing data. For your specific home's radon level, you'll need a radon test kit.