Radon zones in Massachusetts
Last updated
EPA’s Map of Radon Zones places 14 Massachusetts counties in its three radon potential zones: 3 in Zone 1 (highest), 10 in Zone 2 (moderate), and 1 in Zone 3 (low).
What this means for Massachusetts homes
Most Massachusetts counties fall in Zone 2. EPA predicts moderate average indoor levels (2 to 4 pCi/L) across much of Massachusetts. Many homes will be below the action level, but many will not, and only a test can tell which.
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.
Massachusetts radon program
EPA lists the following state contact for Massachusetts: MA Dept. of Public Health, Radiation Control Program, phone 617-624-6000. Website: www.mass.gov/dph/rcp. State programs can tell you about local testing data, free or discounted test kits, disclosure rules for home sales, and credentialed radon professionals.
Massachusetts counties and their EPA radon zones
| County | EPA radon zone |
|---|---|
| Barnstable County | Zone 2 |
| Berkshire County | Zone 2 |
| Bristol County | Zone 2 |
| Dukes County | Zone 2 |
| Essex County | Zone 1 |
| Franklin County | Zone 2 |
| Hampden County | Zone 2 |
| Hampshire County | Zone 2 |
| Middlesex County | Zone 1 |
| Nantucket County | Zone 2 |
| Norfolk County | Zone 2 |
| Plymouth County | Zone 2 |
| Suffolk County | Zone 3 |
| Worcester County | Zone 1 |
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.