Radon Levels in Connecticut

8 counties — 4 high risk, 3 moderate, 1 low risk

4
3
1
Zone 1 High (50.0%) Zone 2 Moderate (37.5%) Zone 3 Low (12.5%)

Connecticut Radon Zone Map

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

Highest-Risk Counties

Fairfield27% above action level
Middlesex33.3% above action level
New Haven33.8% above action level
New London42.3% above action level

Check Your Connecticut ZIP Code

All 8 Counties — By Radon Risk

CountyEPA ZoneTests% Above 4 pCi/L
Fairfield High 163 27%
Middlesex High 36 33.3%
New Haven High 160 33.8%
New London High 52 42.3%
Litchfield Moderate 42 40.5%
Tolland Moderate 25 36%
Windham Moderate 22 45.5%
Hartford Low 157 36.3%

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

Frequently Asked Questions

How many counties in Connecticut have high radon risk?

Connecticut has 4 counties classified as EPA Zone 1 (high radon risk), 3 as Zone 2 (moderate), and 1 as Zone 3 (low risk).

Is radon a problem in Connecticut?

Connecticut has 4 high-risk counties where elevated radon is likely. The EPA recommends all homes in Connecticut be tested for radon, regardless of which zone they're in.

How do I check radon levels for my Connecticut 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.