Radon Levels in New Hampshire

10 counties — 1 high risk, 9 moderate, 0 low risk

1
9
Zone 1 High (10.0%) Zone 2 Moderate (90.0%) Zone 3 Low (0.0%)

New Hampshire Radon Zone Map

Counties colored by EPA radon zone. Red = Zone 1, Orange = Zone 2, Green = Zone 3.

Highest-Risk Counties

Carroll41.7% above action level

Check Your New Hampshire ZIP Code

All 10 Counties — By Radon Risk

CountyEPA ZoneTests% Above 4 pCi/L
Carroll High 12 41.7%
Belknap Moderate 14 50%
Cheshire Moderate 17 58.8%
Coos Moderate 8 75%
Grafton Moderate 15 46.7%
Hillsborough Moderate 67 43.3%
Merrimack Moderate 24 58.3%
Rockingham Moderate 55 54.5%
Strafford Moderate 21 61.9%
Sullivan Moderate 10 60%

Sources: EPA Map of Radon Zones, CDC Environmental Health Tracking Network

Frequently Asked Questions

How many counties in New Hampshire have high radon risk?

New Hampshire has 1 counties classified as EPA Zone 1 (high radon risk), 9 as Zone 2 (moderate), and 0 as Zone 3 (low risk).

Is radon a problem in New Hampshire?

New Hampshire has 1 high-risk counties where elevated radon is likely. The EPA recommends all homes in New Hampshire be tested for radon, regardless of which zone they're in.

How do I check radon levels for my New Hampshire address?

Enter your ZIP code in the search box above to see your county's EPA radon zone and available testing data. For your specific home's radon level, you'll need a radon test kit.