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Radon zones in Connecticut

The EPA assigns every county in Connecticut to one of three radon potential zones. 4 are in Zone 1, the highest category.

8
Counties
4
Zone 1 counties
Predicted average above 4 pCi/L
3
Zone 2 counties
Predicted average 2-4 pCi/L
1
Zone 3 counties
Predicted average below 2 pCi/L

The map

Radon potential across Connecticut

Every county in Connecticut, 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 · 4Zone 2 · 3Zone 3 · 1

Hover a county · click to open it

County by county

All 8 Connecticut counties

Zone 1 · > 4 pCi/LZone 2 · 2 - 4 pCi/LZone 3 · < 2 pCi/L
CountyZonePopulationCOPDSmokingLung ca. deaths
Fairfield County1 - - - 21.4
Middlesex County1 - - - 25.2
New Haven County1 - - - 30.1
New London County1 - - - 33.4
Litchfield County2 - - - 30.6
Tolland County2 - - - 29.4
Windham County2 - - - 38.8
Hartford County3 - - - 26.9

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 Connecticut

These 4 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