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 85 cities.
Updated August 16, 2026
Highest city
12.9pCi/L
China
Maine city average
3.6pCi/L
across 85 cities
Above action level
26/ 85
cities
| # | Location | Avg level | Monitors | vs action level |
|---|---|---|---|---|
| 1 | China | 12.9 pCi/L | 6 | 3.2× over |
| 2 | Norway | 9.2 pCi/L | 10 | 2.3× over |
| 3 | Trenton | 8.8 pCi/L | 10 | 2.2× over |
| 4 | Caribou | 8.7 pCi/L | 6 | 2.2× over |
| 5 | Limestone | 8.0 pCi/L | 18 | 2.0× over |
| 6 | Gorham | 7.8 pCi/L | 20 | 2.0× over |
| 7 | North Windham | 7.1 pCi/L | 15 | 1.8× over |
| 8 | New Gloucester | 6.9 pCi/L | 11 | 1.7× over |
| 9 | Raymond | 6.7 pCi/L | 20 | 1.7× over |
| 10 | West Paris | 6.7 pCi/L | 12 | 1.7× over |
| 11 | Phippsburg | 6.2 pCi/L | 11 | 1.5× over |
| 12 | Fort Fairfield | 5.8 pCi/L | 6 | 1.4× over |
| 13 | Bethel | 5.5 pCi/L | 13 | 1.4× over |
| 14 | Bridgton | 5.4 pCi/L | 13 | 1.3× over |
| 15 | Cumberland Center | 5.3 pCi/L | 34 | 1.3× over |
| 16 | Augusta | 5.3 pCi/L | 8 | 1.3× over |
| 17 | Westbrook | 5.0 pCi/L | 15 | 1.3× over |
| 18 | Houlton | 5.0 pCi/L | 18 | 1.3× over |
| 19 | York Harbor | 4.8 pCi/L | 19 | 1.2× over |
| 20 | Lisbon | 4.6 pCi/L | 8 | 1.1× over |
| 21 | West Scarborough | 4.6 pCi/L | 9 | 1.1× over |
| 22 | South Windham | 4.2 pCi/L | 25 | 1.0× over |
| 23 | Wells Beach Station | 4.1 pCi/L | 17 | 1.0× over |
| 24 | Carmel | 4.1 pCi/L | 10 | 1.0× over |
| 25 | Cape Neddick | 4.1 pCi/L | 10 | 1.0× over |
| 26 | Steep Falls | 4.0 pCi/L | 9 | 1.0× over |
| ✓ Below EPA action level (4 pCi/L) | ||||
| 27 | Topsham | 3.9 pCi/L | 10 | 1.0× under |
| 28 | Ogunquit | 3.8 pCi/L | 19 | 0.9× under |
| 29 | Lovell | 3.7 pCi/L | 10 | 0.9× under |
| 30 | Lewiston | 3.7 pCi/L | 7 | 0.9× under |
| 31 | Lisbon Falls | 3.7 pCi/L | 7 | 0.9× under |
| 32 | Boothbay Harbor | 3.6 pCi/L | 6 | 0.9× under |
| 33 | Calais | 3.5 pCi/L | 14 | 0.9× under |
| 34 | Presque Isle | 3.5 pCi/L | 8 | 0.9× under |
| 35 | Wiscasset | 3.5 pCi/L | 9 | 0.9× under |
| 36 | Brunswick | 3.4 pCi/L | 23 | 0.9× under |
| 37 | Dayton | 3.3 pCi/L | 11 | 0.8× under |
| 38 | Fryeburg | 3.3 pCi/L | 7 | 0.8× under |
| 39 | Kennebunkport | 3.1 pCi/L | 8 | 0.8× under |
| 40 | Hermon | 3.1 pCi/L | 7 | 0.8× under |
| 41 | North Bath | 3.0 pCi/L | 6 | 0.8× under |
| 42 | Kingfield | 3.0 pCi/L | 6 | 0.7× under |
| 43 | Falmouth Foreside | 2.9 pCi/L | 15 | 0.7× under |
| 44 | Biddeford | 2.9 pCi/L | 11 | 0.7× under |
| 45 | Tremont | 2.8 pCi/L | 16 | 0.7× under |
| 46 | Falmouth | 2.8 pCi/L | 34 | 0.7× under |
| 47 | Scarborough | 2.8 pCi/L | 14 | 0.7× under |
| 48 | Kittery | 2.8 pCi/L | 7 | 0.7× under |
| 49 | South Portland Gardens | 2.8 pCi/L | 27 | 0.7× under |
| 50 | Eliot | 2.7 pCi/L | 10 | 0.7× under |
| 51 | Boothbay | 2.7 pCi/L | 11 | 0.7× under |
| 52 | Madawaska | 2.6 pCi/L | 22 | 0.7× under |
| 53 | Waterboro | 2.6 pCi/L | 6 | 0.7× under |
| 54 | Portland | 2.6 pCi/L | 51 | 0.7× under |
| 55 | Hallowell | 2.6 pCi/L | 13 | 0.6× under |
| 56 | Freeport | 2.6 pCi/L | 24 | 0.6× under |
| 57 | Camden | 2.5 pCi/L | 11 | 0.6× under |
| 58 | Kittery Point | 2.5 pCi/L | 14 | 0.6× under |
| 59 | Fort Kent | 2.5 pCi/L | 11 | 0.6× under |
| 60 | Saco | 2.4 pCi/L | 13 | 0.6× under |
| 61 | Richmond | 2.3 pCi/L | 9 | 0.6× under |
| 62 | South Portland | 2.3 pCi/L | 52 | 0.6× under |
| 63 | Buxton | 2.3 pCi/L | 15 | 0.6× under |
| 64 | Yarmouth | 2.3 pCi/L | 29 | 0.6× under |
| 65 | Ellsworth | 2.2 pCi/L | 8 | 0.6× under |
| 66 | Harpswell Center | 2.2 pCi/L | 11 | 0.5× under |
| 67 | Minot | 2.2 pCi/L | 7 | 0.5× under |
| 68 | Auburn | 2.2 pCi/L | 14 | 0.5× under |
| 69 | Arundel | 2.1 pCi/L | 7 | 0.5× under |
| 70 | Berwick | 1.9 pCi/L | 8 | 0.5× under |
| 71 | Kennebunk | 1.8 pCi/L | 7 | 0.4× under |
| 72 | Millinocket | 1.8 pCi/L | 9 | 0.4× under |
| 73 | Sangerville | 1.7 pCi/L | 9 | 0.4× under |
| 74 | Bangor | 1.7 pCi/L | 26 | 0.4× under |
| 75 | Belfast | 1.7 pCi/L | 13 | 0.4× under |
| 76 | Bar Harbor | 1.7 pCi/L | 12 | 0.4× under |
| 77 | Eastport | 1.6 pCi/L | 9 | 0.4× under |
| 78 | Damariscotta | 1.6 pCi/L | 6 | 0.4× under |
| 79 | Hampden | 1.3 pCi/L | 9 | 0.3× under |
| 80 | West Kennebunk | 1.3 pCi/L | 9 | 0.3× under |
| 81 | Palermo | 1.2 pCi/L | 6 | 0.3× under |
| 82 | Belgrade | 1.2 pCi/L | 7 | 0.3× under |
| 83 | Rockport | 1.1 pCi/L | 9 | 0.3× under |
| 84 | Bath | 0.8 pCi/L | 6 | 0.2× under |
| 85 | Bristol | 0.8 pCi/L | 6 | 0.2× under |