Radon Risk in Connecticut
EPA zone data and CDC radon averages for all 8 counties in Connecticut.
Tipper on radon in Connecticut
Connecticut has a statewide average radon level of 4.25 pCi/L, above the EPA's action level of 4 pCi/L. That puts Connecticut among the higher-risk states in the country for indoor radon. If you live here, testing your home is genuinely important.
Looking at the zone breakdown: 4 of Connecticut's 8 counties are EPA Zone 1 (high risk), 3 are Zone 2 (moderate), and 1 are Zone 3 (low). That means 50% of the state falls into the highest risk category, counties where the EPA predicts average indoor levels above 4 pCi/L. Use the county list below to find your area and see the most specific data available.
Within Connecticut, the spread is notable. Litchfield County has the highest measured average in the state at 6.9 pCi/L. Hartford County sits at the other end with 3.1 pCi/L. 4 counties have a measured average above 4 pCi/L. Remember: these are averages. Individual homes can test significantly higher or lower than their county average depending on construction, foundation type, and ventilation.
Tipper's recommendation for Connecticut residents: if you haven't tested your home, start there. A short-term test kit costs around $15 and gives you a result in 48 hours. If your home tests at or above 4 pCi/L, a professional mitigation system (typically $800–$2,000 depending on your foundation and home size) will reliably bring levels down.
Sources: EPA Radon Zone Map, CDC Environmental Public Health Tracking Network
Why Connecticut's Geology Matters
Connecticut's radon risk is driven by underlying metamorphic and igneous bedrock, particularly granite and gneiss formations. The Connecticut Valley has sedimentary brownstone. Northern and eastern parts of the state, with higher-uranium crystalline rock, tend to produce more elevated readings.
Radon Disclosure Laws
Connecticut requires radon testing information to be disclosed during residential real estate transactions. Sellers must provide any known test results to buyers.
Highest Radon Averages
Lowest Radon Averages
All Counties in Connecticut
Click any county to see its full radon data and local contractors.
Showing 8 of 8 counties in Connecticut. Zone classifications from the EPA. Average pCi/L from CDC tracking data.
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Contractors
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