New Hampshire Cities Ranked by Indoor Radon Levels
Measured averages from Airthings devices across New Hampshire, USA. Action level: 4 pCi/L — the threshold at which remediation is recommended.
Madison has the highest measured indoor radon in New Hampshire at 14.4 pCi/L, based on Airthings measurements across 110 cities.
Updated October 19, 2026
Highest city
14.4pCi/L
Madison
New Hampshire city average
4.0pCi/L
across 110 cities
Above action level
35/ 110
cities
| # | Location | Avg level | vs action level |
|---|---|---|---|
| 1 | Madison | 14.4 pCi/L | 3.6× over |
| 2 | Hooksett | 12.0 pCi/L | 3.0× over |
| 3 | Conway | 11.4 pCi/L | 2.9× over |
| 4 | Lee | 10.3 pCi/L | 2.6× over |
| 5 | Ossipee | 9.6 pCi/L | 2.4× over |
| 6 | North Conway | 9.5 pCi/L | 2.4× over |
| 7 | Sandwich | 8.8 pCi/L | 2.2× over |
| 8 | Rye | 8.6 pCi/L | 2.1× over |
| 9 | Northwood | 8.4 pCi/L | 2.1× over |
| 10 | New Durham | 8.3 pCi/L | 2.1× over |
| 11 | Pinardville | 8.2 pCi/L | 2.1× over |
| 12 | Pelham | 7.8 pCi/L | 1.9× over |
| 13 | Mont Vernon | 7.6 pCi/L | 1.9× over |
| 14 | Raymond | 7.2 pCi/L | 1.8× over |
| 15 | Thornton | 6.9 pCi/L | 1.7× over |
| 16 | Auburn | 6.8 pCi/L | 1.7× over |
| 17 | Derry | 6.5 pCi/L | 1.6× over |
| 18 | Sunapee | 6.3 pCi/L | 1.6× over |
| 19 | Freedom | 6.1 pCi/L | 1.5× over |
| 20 | Wilmot | 5.8 pCi/L | 1.4× over |
| 21 | South Hooksett | 5.6 pCi/L | 1.4× over |
| 22 | Londonderry | 5.5 pCi/L | 1.4× over |
| 23 | Farmington | 5.5 pCi/L | 1.4× over |
| 24 | Kingston | 5.1 pCi/L | 1.3× over |
| 25 | Whitefield | 5.0 pCi/L | 1.2× over |
| 26 | Woodstock | 4.9 pCi/L | 1.2× over |
| 27 | Candia | 4.8 pCi/L | 1.2× over |
| 28 | Sandown | 4.6 pCi/L | 1.1× over |
| 29 | Littleton | 4.5 pCi/L | 1.1× over |
| 30 | Stratham Station | 4.3 pCi/L | 1.1× over |
| 31 | Barrington | 4.3 pCi/L | 1.1× over |
| 32 | Strafford | 4.1 pCi/L | 1.0× over |
| 33 | Merrimack | 4.1 pCi/L | 1.0× over |
| 34 | Epping | 4.1 pCi/L | 1.0× over |
| 35 | Windham | 4.1 pCi/L | 1.0× over |
| ✓ Below EPA action level (4 pCi/L) | |||
| 36 | Goffstown | 4.0 pCi/L | 1.0× under |
| 37 | Portsmouth | 3.9 pCi/L | 1.0× under |
| 38 | Orford | 3.8 pCi/L | 0.9× under |
| 39 | Wakefield | 3.7 pCi/L | 0.9× under |
| 40 | Lyndeborough | 3.7 pCi/L | 0.9× under |
| 41 | Rindge | 3.7 pCi/L | 0.9× under |
| 42 | East Kingston | 3.6 pCi/L | 0.9× under |
| 43 | Hollis | 3.6 pCi/L | 0.9× under |
| 44 | Litchfield | 3.6 pCi/L | 0.9× under |
| 45 | Durham | 3.5 pCi/L | 0.9× under |
| 46 | Rochester | 3.5 pCi/L | 0.9× under |
| 47 | Wilton | 3.5 pCi/L | 0.9× under |
| 48 | Greenland | 3.5 pCi/L | 0.9× under |
| 49 | Plymouth | 3.4 pCi/L | 0.9× under |
| 50 | Nashua | 3.4 pCi/L | 0.8× under |
| 51 | Westmoreland | 3.4 pCi/L | 0.8× under |
| 52 | Milford | 3.4 pCi/L | 0.8× under |
| 53 | Barnstead | 3.4 pCi/L | 0.8× under |
| 54 | Newbury | 3.4 pCi/L | 0.8× under |
| 55 | Exeter | 3.3 pCi/L | 0.8× under |
| 56 | Gilford | 3.3 pCi/L | 0.8× under |
| 57 | New London | 3.3 pCi/L | 0.8× under |
| 58 | Dover | 3.2 pCi/L | 0.8× under |
| 59 | Hudson | 3.2 pCi/L | 0.8× under |
| 60 | Wolfeboro | 3.1 pCi/L | 0.8× under |
| 61 | New Boston | 3.1 pCi/L | 0.8× under |
| 62 | Deerfield | 3.1 pCi/L | 0.8× under |
| 63 | Andover | 3.1 pCi/L | 0.8× under |
| 64 | North Hampton | 3.1 pCi/L | 0.8× under |
| 65 | Salem | 3.0 pCi/L | 0.8× under |
| 66 | Colebrook | 3.0 pCi/L | 0.7× under |
| 67 | Concord | 3.0 pCi/L | 0.7× under |
| 68 | Gorham | 3.0 pCi/L | 0.7× under |
| 69 | Bedford | 3.0 pCi/L | 0.7× under |
| 70 | Sanbornton | 2.9 pCi/L | 0.7× under |
| 71 | Meredith | 2.8 pCi/L | 0.7× under |
| 72 | Brookline | 2.8 pCi/L | 0.7× under |
| 73 | Nottingham | 2.8 pCi/L | 0.7× under |
| 74 | Plaistow | 2.8 pCi/L | 0.7× under |
| 75 | Newton | 2.7 pCi/L | 0.7× under |
| 76 | Brentwood | 2.7 pCi/L | 0.7× under |
| 77 | Greenfield | 2.6 pCi/L | 0.7× under |
| 78 | Weare | 2.6 pCi/L | 0.7× under |
| 79 | Bow Bog | 2.5 pCi/L | 0.6× under |
| 80 | Derry Village | 2.5 pCi/L | 0.6× under |
| 81 | Sanbornville | 2.5 pCi/L | 0.6× under |
| 82 | Atkinson | 2.4 pCi/L | 0.6× under |
| 83 | Newport | 2.3 pCi/L | 0.6× under |
| 84 | Hopkinton | 2.3 pCi/L | 0.6× under |
| 85 | Danville | 2.2 pCi/L | 0.6× under |
| 86 | Gilmanton | 2.2 pCi/L | 0.6× under |
| 87 | Manchester | 2.1 pCi/L | 0.5× under |
| 88 | Hampstead | 2.1 pCi/L | 0.5× under |
| 89 | Chester | 2.0 pCi/L | 0.5× under |
| 90 | Laconia | 2.0 pCi/L | 0.5× under |
| 91 | Grantham | 2.0 pCi/L | 0.5× under |
| 92 | Lyme | 1.9 pCi/L | 0.5× under |
| 93 | Haverhill | 1.9 pCi/L | 0.5× under |
| 94 | Lebanon | 1.9 pCi/L | 0.5× under |
| 95 | Center Harbor | 1.9 pCi/L | 0.5× under |
| 96 | Somersworth | 1.8 pCi/L | 0.4× under |
| 97 | New Castle | 1.8 pCi/L | 0.4× under |
| 98 | East Concord | 1.7 pCi/L | 0.4× under |
| 99 | Holderness | 1.6 pCi/L | 0.4× under |
| 100 | Hanover | 1.6 pCi/L | 0.4× under |
| 101 | Keene | 1.6 pCi/L | 0.4× under |
| 102 | Fitzwilliam | 1.6 pCi/L | 0.4× under |
| 103 | Salisbury | 1.6 pCi/L | 0.4× under |
| 104 | Hampton | 1.5 pCi/L | 0.4× under |
| 105 | Moultonborough | 1.4 pCi/L | 0.4× under |
| 106 | Peterborough | 1.4 pCi/L | 0.4× under |
| 107 | Enfield | 1.3 pCi/L | 0.3× under |
| 108 | Alexandria | 1.3 pCi/L | 0.3× under |
| 109 | Antrim | 1.0 pCi/L | 0.2× under |
| 110 | Newmarket | 0.9 pCi/L | 0.2× under |