Radon in New Hampshire

Of New Hampshire's 10 counties and county equivalents, EPA places 1 in Zone 1, 9 in Zone 2. Zones are county-wide predictions; testing is the only way to know your home's level.

39%

of New Hampshire residences tested reported elevated radon (2007–2025 test data).

5.9 pCi/L

estimated average indoor radon in NH, vs. 1.3 pCi/L nationally.

>100 pCi/L

readings have been reported in every NH county.

Source: NH DHHS Radon Program, “Residential Radon Risk: Local Levels and Testing Rates,” data brief, July 2026.

New Hampshire residents can order a free radon test kit through the state program at aelabs.com/nh (per NH DHHS).

Radon in the news

New Hampshire stories

Rye library closes due to high radon levels: How to test your home for free in NH
Seacoastonline.com · 2025-03-04
Living in the ‘Granite State’ means elevated risk for radon exposure, and in turn, lung cancer
New Hampshire Bulletin · 2023-02-27
NH has elevated risk for radon
Concord Monitor · 2023-02-27
Study: 55 percent of New Hampshire’s groundwater probably has elevated radon levels
NH Business Review · 2023-02-22
New study estimates 55% of New Hampshire’s groundwater probably has elevated radon levels
New Hampshire Public Radio · 2023-02-20

Headlines link to the original publishers via Google News. Updated 2026-10-27.

All 10 counties

County	EPA 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

Source: EPA radon zones spreadsheet (EPA 402/A-16/001).