Does radon mitigation work?

Yes. Properly installed systems typically reduce radon levels significantly. Post-mitigation testing confirms performance.

Radon Levels, Testing and Mitigation in New Hampshire

Q: What radon level is considered high?

The EPA action level is 4.0 pCi/L. Many homeowners also choose to fix levels between 2.0 and 4.0 pCi/L.

Q: How much does radon mitigation cost in New Hampshire?

Radon mitigation typically costs between $800 and $2,500 depending on foundation type and severity.

New Hampshire has 10 counties, with 1 classified as EPA Zone 1 (highest risk). With an average radon level of 9.01 pCi/L, New Hampshire state testing data reveals significantly elevated risks across multiple counties. Testing is highly recommended.

New Hampshire is the fifth smallest state in terms of size and the ninth least populous in the entire US. The state does not have an active radon program.

9.01

Avg. pCi/L

Counties

Zone 1 Counties

New Hampshire Radon Map

Zone 1 — High

Zone 2 — Moderate

Zone 3 — Low

New Hampshire Metro Areas

Explore radon data organized by metro region, including average levels, hotspot cities, and local mitigation professionals.

Most Active Radon Markets in New Hampshire

Cities with the most user-submitted radon test data, ranked by number of submissions.

City	Avg User Radon Level	Submissions
Tamworth	12.67 pCi/L	6
Freedom	10.75 pCi/L	4

New Hampshire Counties by EPA Radon Zone

All 10 New Hampshire counties with their EPA radon zone classification and user-submitted average radon levels.

Zone 1 — High Risk

Predicted avg. indoor levels > 4.0 pCi/L

Zone 1 1 counties

Carroll County Zone 1

Avg: 10.5 pCi/L

Zone 2 — Moderate Risk

Predicted avg. indoor levels 2–4 pCi/L

Zone 2 9 counties

Belknap County Zone 2

Avg: 6.3 pCi/L

Cheshire County Zone 2

Avg: 6.3 pCi/L

Coos County Zone 2

Avg: 6.5 pCi/L

Grafton County Zone 2

Avg: 11.3 pCi/L

Hillsborough County Zone 2

Avg: 7.0 pCi/L

Merrimack County Zone 2

Avg: 9.6 pCi/L

Rockingham County Zone 2

Avg: 8.3 pCi/L

Strafford County Zone 2

Avg: 11.0 pCi/L

Sullivan County Zone 2

Avg: 9.7 pCi/L

New Hampshire Cities & Towns

Browse radon data for individual cities across New Hampshire. Each city page includes user-submitted radon levels, local contractors, and mitigation resources.

Acworth Alstead Alton Alton Bay Amherst Andover Antrim Ashland Ashuelot Atkinson Auburn Barnstead Barrington Bartlett Bath Bedford Belmont Bennington Berlin Bethlehem Bow Bradford Bristol Brookline Campton Canaan Candia Canterbury Center Barnstead Center Conway Center Harbor Center Ossipee Center Sandwich Center Strafford Center Tuftonboro Charlestown Chester Chesterfield Chichester Chocorua Claremont Colebrook Concord Contoocook Conway Cornish Danbury Danville Deerfield Derry Dover Dublin Dunbarton Durham East Hampstead East Kingston East Wakefield Effingham Elkins Enfield Epping Epsom Errol Etna Exeter Farmington Fitzwilliam Francestown Franconia Franklin Freedom Fremont Gilford Gilmanton Gilmanton Iron Works Gilsum Glen Goffstown Gorham Goshen Grafton Grantham Greenfield Greenland Greenville Groveton Hampstead Hampton Hampton Falls Hancock Hanover Harrisville Haverhill Hebron Henniker Hill Hillsborough Hinsdale Holderness Hollis Hooksett Hudson Intervale Jackson Jaffrey Jefferson Keene Kingston Laconia Lancaster Lebanon Lee Lempster Lincoln Lisbon Litchfield Littleton Londonderry Loudon Lyme Lyndeborough Madbury Madison Manchester Marlborough Marlow Meredith Meriden Merrimack Milan Milford Milton Milton Mills Mirror Lake Monroe Mont Vernon Moultonborough Nashua Nelson New Boston New Durham New Hampton New Ipswich New London Newbury Newfields Newington Newmarket Newport Newton North Conway North Hampton North Haverhill North Sandwich North Stratford North Walpole North Woodstock Northwood Nottingham Orford Ossipee Pelham Peterborough Piermont Pike Pittsburg Pittsfield Plainfield Plaistow Plymouth Portsmouth Randolph Raymond Rindge Rochester Rollinsford Rumney Rye Salem Salisbury Sanbornton Sanbornville Sandown Seabrook Silver Lake Somersworth South Acworth South Tamworth Spofford Springfield Stoddard Strafford Stratham Sugar Hill Sullivan Sunapee Suncook Swanzey Tamworth Temple Thornton Tilton Troy Union Walpole Warner Warren Washington Weare Wentworth West Chesterfield West Lebanon West Nottingham West Ossipee Westmoreland Whitefield Wilmot Wilton Winchester Windham Wolfeboro Wonalancet Woodsville

Frequently Asked Questions About Radon in New Hampshire

What radon level is considered "high"?

The EPA action level is 4.0 pCi/L — many homeowners also choose to fix levels between 2.0 and 4.0 pCi/L. Any home with levels at or above 4.0 pCi/L should be mitigated.

How much does radon mitigation cost in New Hampshire?

Radon mitigation typically costs between $800 and $2,500, depending on foundation type and radon severity. A standard sub-slab depressurization system usually falls in the $1,000–$1,500 range.

Does mitigation actually work?

Yes — properly installed systems typically reduce radon levels by up to 99%. A post-mitigation test confirms the system is working correctly, and many homeowners re-test periodically.

Should I test again after mitigation?

Yes. A post-mitigation test is the proof your system is working. The EPA recommends testing within 30 days of installation and retesting every two years.

What EPA Radon Zone is my New Hampshire county in?

New Hampshire counties are classified into three EPA Radon Zones. Zone 1 (highest risk, >4 pCi/L) indicates the most concern. Zone 2 (moderate, 2–4 pCi/L) and Zone 3 (lowest, <2 pCi/L) round out the classification. Use the county directory above to find your specific county's zone and data.