Radon zones in New Hampshire
Last updated
EPA’s Map of Radon Zones places 10 New Hampshire counties in its three radon potential zones: 1 in Zone 1 (highest), 9 in Zone 2 (moderate), and 0 in Zone 3 (low).
What this means for New Hampshire homes
Most New Hampshire counties fall in Zone 2. EPA predicts moderate average indoor levels (2 to 4 pCi/L) across much of New Hampshire. 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.
New Hampshire radon program
EPA lists the following state contact for New Hampshire: NH Department of Health and Human Services, phone 603-271-1708. Website: www.dhhs.nh.gov/programs-services/environmental-health-and-you/radon. State programs can tell you about local testing data, free or discounted test kits, disclosure rules for home sales, and credentialed radon professionals.
New Hampshire counties and their EPA radon zones
| County | EPA radon zone |
|---|---|
| Belknap County | Zone 2 |
| Carroll County | Zone 1 |
| Cheshire County | Zone 2 |
| Coos County | Zone 2 |
| Grafton County | Zone 2 |
| Hillsborough County | Zone 2 |
| Merrimack County | Zone 2 |
| Rockingham County | Zone 2 |
| Strafford County | Zone 2 |
| Sullivan 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.