Maine Cities Ranked by Indoor Radon Levels
Measured averages from Airthings devices across Maine, USA. Action level: 4 pCi/L — the threshold at which remediation is recommended.
China has the highest measured indoor radon in Maine at 12.9 pCi/L, based on Airthings measurements across 102 cities.
Updated October 19, 2026
Highest city
12.9pCi/L
China
Maine city average
3.7pCi/L
across 102 cities
Above action level
34/ 102
cities
| # | Location | Avg level | vs action level |
|---|---|---|---|
| 1 | China | 12.9 pCi/L | 3.2× over |
| 2 | Old Orchard Beach | 12.3 pCi/L | 3.1× over |
| 3 | Limestone | 9.9 pCi/L | 2.5× over |
| 4 | Franklin | 8.9 pCi/L | 2.2× over |
| 5 | Trenton | 8.8 pCi/L | 2.2× over |
| 6 | Norway | 8.7 pCi/L | 2.2× over |
| 7 | Harrison | 8.2 pCi/L | 2.0× over |
| 8 | Caribou | 8.0 pCi/L | 2.0× over |
| 9 | Gorham | 7.4 pCi/L | 1.8× over |
| 10 | New Gloucester | 6.9 pCi/L | 1.7× over |
| 11 | North Windham | 6.7 pCi/L | 1.7× over |
| 12 | West Paris | 6.7 pCi/L | 1.7× over |
| 13 | Raymond | 6.6 pCi/L | 1.7× over |
| 14 | Phippsburg | 6.2 pCi/L | 1.5× over |
| 15 | Fort Fairfield | 5.8 pCi/L | 1.4× over |
| 16 | North Berwick | 5.5 pCi/L | 1.4× over |
| 17 | Bethel | 5.4 pCi/L | 1.3× over |
| 18 | Bridgton | 5.4 pCi/L | 1.3× over |
| 19 | Cumberland Center | 5.3 pCi/L | 1.3× over |
| 20 | Lincoln | 5.3 pCi/L | 1.3× over |
| 21 | Westbrook | 5.2 pCi/L | 1.3× over |
| 22 | Houlton | 5.0 pCi/L | 1.3× over |
| 23 | Augusta | 5.0 pCi/L | 1.2× over |
| 24 | Lisbon | 4.6 pCi/L | 1.1× over |
| 25 | York Harbor | 4.5 pCi/L | 1.1× over |
| 26 | Castine | 4.4 pCi/L | 1.1× over |
| 27 | Madison | 4.3 pCi/L | 1.1× over |
| 28 | West Scarborough | 4.2 pCi/L | 1.0× over |
| 29 | South Windham | 4.2 pCi/L | 1.0× over |
| 30 | Carmel | 4.1 pCi/L | 1.0× over |
| 31 | South Berwick | 4.1 pCi/L | 1.0× over |
| 32 | Cape Neddick | 4.1 pCi/L | 1.0× over |
| 33 | Greene | 4.0 pCi/L | 1.0× over |
| 34 | Springvale | 4.0 pCi/L | 1.0× over |
| ✓ Below EPA action level (4 pCi/L) | |||
| 35 | Wells Beach Station | 4.0 pCi/L | 1.0× under |
| 36 | Steep Falls | 3.9 pCi/L | 1.0× under |
| 37 | Phillips | 3.8 pCi/L | 0.9× under |
| 38 | Ogunquit | 3.8 pCi/L | 0.9× under |
| 39 | Lovell | 3.7 pCi/L | 0.9× under |
| 40 | Lewiston | 3.7 pCi/L | 0.9× under |
| 41 | Lisbon Falls | 3.7 pCi/L | 0.9× under |
| 42 | Topsham | 3.6 pCi/L | 0.9× under |
| 43 | Boothbay Harbor | 3.6 pCi/L | 0.9× under |
| 44 | Presque Isle | 3.5 pCi/L | 0.9× under |
| 45 | Calais | 3.3 pCi/L | 0.8× under |
| 46 | Dayton | 3.3 pCi/L | 0.8× under |
| 47 | Wiscasset | 3.3 pCi/L | 0.8× under |
| 48 | Fryeburg | 3.3 pCi/L | 0.8× under |
| 49 | Greenville | 3.3 pCi/L | 0.8× under |
| 50 | Brunswick | 3.2 pCi/L | 0.8× under |
| 51 | Falmouth Foreside | 3.0 pCi/L | 0.8× under |
| 52 | North Bath | 3.0 pCi/L | 0.8× under |
| 53 | Kennebunkport | 3.0 pCi/L | 0.7× under |
| 54 | Kingfield | 3.0 pCi/L | 0.7× under |
| 55 | Tremont | 2.8 pCi/L | 0.7× under |
| 56 | Kittery | 2.8 pCi/L | 0.7× under |
| 57 | Falmouth | 2.7 pCi/L | 0.7× under |
| 58 | Scarborough | 2.7 pCi/L | 0.7× under |
| 59 | Hermon | 2.7 pCi/L | 0.7× under |
| 60 | South Portland Gardens | 2.7 pCi/L | 0.7× under |
| 61 | Biddeford | 2.7 pCi/L | 0.7× under |
| 62 | Eliot | 2.7 pCi/L | 0.7× under |
| 63 | Boothbay | 2.7 pCi/L | 0.7× under |
| 64 | Portland | 2.7 pCi/L | 0.7× under |
| 65 | Madawaska | 2.6 pCi/L | 0.7× under |
| 66 | Waterboro | 2.6 pCi/L | 0.7× under |
| 67 | Saco | 2.6 pCi/L | 0.6× under |
| 68 | Camden | 2.5 pCi/L | 0.6× under |
| 69 | Hallowell | 2.5 pCi/L | 0.6× under |
| 70 | Fort Kent | 2.5 pCi/L | 0.6× under |
| 71 | Freeport | 2.4 pCi/L | 0.6× under |
| 72 | Hampden | 2.4 pCi/L | 0.6× under |
| 73 | Kittery Point | 2.4 pCi/L | 0.6× under |
| 74 | Kennebunk | 2.4 pCi/L | 0.6× under |
| 75 | Gardiner | 2.4 pCi/L | 0.6× under |
| 76 | South Portland | 2.3 pCi/L | 0.6× under |
| 77 | Buxton | 2.3 pCi/L | 0.6× under |
| 78 | Richmond | 2.3 pCi/L | 0.6× under |
| 79 | Ellsworth | 2.2 pCi/L | 0.6× under |
| 80 | Minot | 2.2 pCi/L | 0.5× under |
| 81 | Yarmouth | 2.1 pCi/L | 0.5× under |
| 82 | Arundel | 2.1 pCi/L | 0.5× under |
| 83 | Harpswell Center | 2.1 pCi/L | 0.5× under |
| 84 | Auburn | 2.0 pCi/L | 0.5× under |
| 85 | Rockland | 1.9 pCi/L | 0.5× under |
| 86 | Berwick | 1.9 pCi/L | 0.5× under |
| 87 | Hope | 1.8 pCi/L | 0.5× under |
| 88 | Millinocket | 1.8 pCi/L | 0.4× under |
| 89 | Sangerville | 1.7 pCi/L | 0.4× under |
| 90 | Rome | 1.7 pCi/L | 0.4× under |
| 91 | Belfast | 1.7 pCi/L | 0.4× under |
| 92 | Bangor | 1.7 pCi/L | 0.4× under |
| 93 | Bar Harbor | 1.7 pCi/L | 0.4× under |
| 94 | Eastport | 1.6 pCi/L | 0.4× under |
| 95 | Damariscotta | 1.6 pCi/L | 0.4× under |
| 96 | West Kennebunk | 1.3 pCi/L | 0.3× under |
| 97 | Palermo | 1.2 pCi/L | 0.3× under |
| 98 | Belgrade | 1.2 pCi/L | 0.3× under |
| 99 | Bristol | 1.1 pCi/L | 0.3× under |
| 100 | Rockport | 1.1 pCi/L | 0.3× under |
| 101 | South Eliot | 0.9 pCi/L | 0.2× under |
| 102 | Bath | 0.9 pCi/L | 0.2× under |