Radon zones in Connecticut
Last updated
EPA’s Map of Radon Zones places 8 Connecticut counties in its three radon potential zones: 4 in Zone 1 (highest), 3 in Zone 2 (moderate), and 1 in Zone 3 (low).
What this means for Connecticut homes
Most Connecticut counties fall in Zone 1. EPA predicts average indoor screening levels above 4 pCi/L across much of Connecticut, so elevated radon is common. Testing is especially worthwhile here, and radon-resistant construction features make sense for new homes.
EPA’s guidance is the same everywhere: test your home, fix it if the level is 4 pCi/L or higher, and consider fixing between 2 and 4 pCi/L. The zone map is from 1993 and should not be used to decide whether a single home needs testing.
Connecticut radon program
EPA lists the following state contact for Connecticut: CT State Department of Public Health, phone 860-509-7300. Website: portal.ct.gov/dph/Environmental-Health/Radon/Radon-Program. State programs can tell you about local testing data, free or discounted test kits, disclosure rules for home sales, and credentialed radon professionals.
Connecticut counties and their EPA radon zones
| County | EPA radon zone |
|---|---|
| Fairfield County | Zone 1 |
| Hartford County | Zone 3 |
| Litchfield County | Zone 2 |
| Middlesex County | Zone 1 |
| New Haven County | Zone 1 |
| New London County | Zone 1 |
| Tolland County | Zone 2 |
| Windham County | Zone 2 |
County names follow the 2020 Census. Zones from the EPA Map of Radon Zones (text version). Rows marked “zone of” use the zone EPA gave the predecessor or surrounding county.
Next steps: read how to test your home, check a result with the level calculator, or look up a single address by ZIP code.