USA Cities Ranked by Indoor Radon Levels
Measured averages from Airthings devices across USA. Action level: 4 pCi/L — the threshold at which remediation is recommended.
East Douglas, Massachusetts has the highest measured indoor radon of any USA city at 19.1 pCi/L, based on Airthings measurements across 5548 cities.
Updated August 16, 2026
Highest city
19.1pCi/L
East Douglas
USA city average
2.8pCi/L
across 5,548 cities
Above action level
1028/ 5548
cities
Showing the 100 highest of 5548 ranked USA cities. For the full list in one place, open a state ranking below.
| # | Location | Avg level | Monitors | vs action level |
|---|---|---|---|---|
| 1 | East Douglas, Massachusetts | 19.1 pCi/L | 10 | 4.8× over |
| 2 | Prospect, Pennsylvania | 17.6 pCi/L | 6 | 4.4× over |
| 3 | Jacobus, Pennsylvania | 17.3 pCi/L | 7 | 4.3× over |
| 4 | Calcutta, Ohio | 16.4 pCi/L | 7 | 4.1× over |
| 5 | Zion, Pennsylvania | 16.4 pCi/L | 10 | 4.1× over |
| 6 | Russellton, Pennsylvania | 15.7 pCi/L | 9 | 3.9× over |
| 7 | Kutztown, Pennsylvania | 15.6 pCi/L | 7 | 3.9× over |
| 8 | Greenville, Pennsylvania | 15.0 pCi/L | 8 | 3.8× over |
| 9 | Grafton, North Dakota | 14.8 pCi/L | 7 | 3.7× over |
| 10 | Atlantic, Iowa | 14.4 pCi/L | 7 | 3.6× over |
| 11 | Madison, New Hampshire | 14.4 pCi/L | 7 | 3.6× over |
| 12 | Palmerton, Pennsylvania | 14.1 pCi/L | 7 | 3.5× over |
| 13 | Manheim, Pennsylvania | 13.6 pCi/L | 13 | 3.4× over |
| 14 | Apollo, Pennsylvania | 13.5 pCi/L | 6 | 3.4× over |
| 15 | Bowling Green, Kentucky | 13.4 pCi/L | 46 | 3.4× over |
| 16 | Akron, Pennsylvania | 13.4 pCi/L | 6 | 3.3× over |
| 17 | Millersburg, Ohio | 13.4 pCi/L | 7 | 3.3× over |
| 18 | Shippensburg, Pennsylvania | 13.2 pCi/L | 8 | 3.3× over |
| 19 | Big Timber, Montana | 13.1 pCi/L | 6 | 3.3× over |
| 20 | China, Maine | 12.9 pCi/L | 6 | 3.2× over |
| 21 | Bloomsburg, Pennsylvania | 12.9 pCi/L | 8 | 3.2× over |
| 22 | Mosheim, Tennessee | 12.6 pCi/L | 6 | 3.2× over |
| 23 | Langdon, North Dakota | 12.5 pCi/L | 9 | 3.1× over |
| 24 | Robesonia, Pennsylvania | 12.4 pCi/L | 7 | 3.1× over |
| 25 | Industry, Pennsylvania | 12.1 pCi/L | 15 | 3.0× over |
| 26 | Doe Valley, Kentucky | 12.0 pCi/L | 7 | 3.0× over |
| 27 | Conway, New Hampshire | 11.8 pCi/L | 12 | 3.0× over |
| 28 | Cherryville, Pennsylvania | 11.7 pCi/L | 7 | 2.9× over |
| 29 | Okauchee Lake, Wisconsin | 11.7 pCi/L | 8 | 2.9× over |
| 30 | Shrewsbury, Pennsylvania | 11.7 pCi/L | 12 | 2.9× over |
| 31 | Hughesville, Pennsylvania | 11.6 pCi/L | 6 | 2.9× over |
| 32 | Heath, Ohio | 11.6 pCi/L | 15 | 2.9× over |
| 33 | Quarryville, Pennsylvania | 11.5 pCi/L | 9 | 2.9× over |
| 34 | Strasburg, Pennsylvania | 11.3 pCi/L | 10 | 2.8× over |
| 35 | Centre Hall, Pennsylvania | 11.3 pCi/L | 8 | 2.8× over |
| 36 | Trentwood, Washington | 11.3 pCi/L | 7 | 2.8× over |
| 37 | Barneveld, Wisconsin | 11.2 pCi/L | 17 | 2.8× over |
| 38 | Wrightsville, Pennsylvania | 11.2 pCi/L | 7 | 2.8× over |
| 39 | Granite Falls, Washington | 11.0 pCi/L | 11 | 2.7× over |
| 40 | Peru, Indiana | 10.9 pCi/L | 6 | 2.7× over |
| 41 | Rushville, Indiana | 10.9 pCi/L | 9 | 2.7× over |
| 42 | Osage, Iowa | 10.9 pCi/L | 6 | 2.7× over |
| 43 | Idaho Springs, Colorado | 10.8 pCi/L | 11 | 2.7× over |
| 44 | Hooksett, New Hampshire | 10.8 pCi/L | 8 | 2.7× over |
| 45 | Stewartstown, Pennsylvania | 10.7 pCi/L | 25 | 2.7× over |
| 46 | Williamsport, Maryland | 10.7 pCi/L | 19 | 2.7× over |
| 47 | Yorktown, Indiana | 10.7 pCi/L | 6 | 2.7× over |
| 48 | Factoryville, Pennsylvania | 10.6 pCi/L | 7 | 2.6× over |
| 49 | Clayton, New York | 10.6 pCi/L | 8 | 2.6× over |
| 50 | Spirit Lake, Idaho | 10.5 pCi/L | 16 | 2.6× over |
| 51 | Scobey, Montana | 10.5 pCi/L | 6 | 2.6× over |
| 52 | Danville, Ohio | 10.3 pCi/L | 6 | 2.6× over |
| 53 | Spencer, Iowa | 10.3 pCi/L | 15 | 2.6× over |
| 54 | Spry, Pennsylvania | 10.3 pCi/L | 15 | 2.6× over |
| 55 | Moorefield, West Virginia | 10.3 pCi/L | 7 | 2.6× over |
| 56 | Lee, New Hampshire | 10.3 pCi/L | 17 | 2.6× over |
| 57 | Rutherford, Pennsylvania | 10.2 pCi/L | 11 | 2.6× over |
| 58 | Mountville, Pennsylvania | 10.2 pCi/L | 7 | 2.6× over |
| 59 | New Glarus, Wisconsin | 10.2 pCi/L | 11 | 2.5× over |
| 60 | Honey Brook, Pennsylvania | 10.1 pCi/L | 7 | 2.5× over |
| 61 | Garden View, Pennsylvania | 10.0 pCi/L | 8 | 2.5× over |
| 62 | North Conway, New Hampshire | 9.9 pCi/L | 21 | 2.5× over |
| 63 | Beaver Falls, Pennsylvania | 9.9 pCi/L | 13 | 2.5× over |
| 64 | Windsor, Pennsylvania | 9.9 pCi/L | 12 | 2.5× over |
| 65 | Gate City, Virginia | 9.9 pCi/L | 6 | 2.5× over |
| 66 | Cornwall, Pennsylvania | 9.8 pCi/L | 11 | 2.5× over |
| 67 | Grinnell, Iowa | 9.8 pCi/L | 6 | 2.5× over |
| 68 | Bellefontaine, Ohio | 9.8 pCi/L | 9 | 2.4× over |
| 69 | Glen Rock, Pennsylvania | 9.8 pCi/L | 8 | 2.4× over |
| 70 | Spurgeon, Tennessee | 9.8 pCi/L | 10 | 2.4× over |
| 71 | Sinking Spring, Pennsylvania | 9.8 pCi/L | 11 | 2.4× over |
| 72 | Dallas Center, Iowa | 9.7 pCi/L | 6 | 2.4× over |
| 73 | Riverside, Pennsylvania | 9.7 pCi/L | 13 | 2.4× over |
| 74 | Ossipee, New Hampshire | 9.6 pCi/L | 11 | 2.4× over |
| 75 | Spirit Lake, Iowa | 9.5 pCi/L | 9 | 2.4× over |
| 76 | Parkville, Pennsylvania | 9.4 pCi/L | 13 | 2.3× over |
| 77 | Hillsdale, Michigan | 9.3 pCi/L | 8 | 2.3× over |
| 78 | Effort, Pennsylvania | 9.3 pCi/L | 7 | 2.3× over |
| 79 | Veradale, Washington | 9.3 pCi/L | 15 | 2.3× over |
| 80 | Afton, Wyoming | 9.3 pCi/L | 16 | 2.3× over |
| 81 | Milan, Illinois | 9.3 pCi/L | 11 | 2.3× over |
| 82 | Susquehanna Trails, Pennsylvania | 9.3 pCi/L | 24 | 2.3× over |
| 83 | Thompson Falls, Montana | 9.3 pCi/L | 7 | 2.3× over |
| 84 | Blacklick Estates, Ohio | 9.3 pCi/L | 9 | 2.3× over |
| 85 | Elizabethtown, Kentucky | 9.2 pCi/L | 21 | 2.3× over |
| 86 | Mount Vernon, Ohio | 9.2 pCi/L | 12 | 2.3× over |
| 87 | Palmyra, Pennsylvania | 9.2 pCi/L | 15 | 2.3× over |
| 88 | Luxemburg, Wisconsin | 9.2 pCi/L | 10 | 2.3× over |
| 89 | Norway, Maine | 9.2 pCi/L | 10 | 2.3× over |
| 90 | Northridge, Ohio | 9.2 pCi/L | 11 | 2.3× over |
| 91 | Winfield, Missouri | 9.1 pCi/L | 7 | 2.3× over |
| 92 | Box Elder, South Dakota | 9.1 pCi/L | 9 | 2.3× over |
| 93 | Trinidad, Colorado | 9.1 pCi/L | 7 | 2.3× over |
| 94 | Red Lion, Pennsylvania | 9.1 pCi/L | 16 | 2.3× over |
| 95 | Sturgis, South Dakota | 9.1 pCi/L | 6 | 2.3× over |
| 96 | Belvidere, New Jersey | 9.0 pCi/L | 10 | 2.3× over |
| 97 | Obetz, Ohio | 9.0 pCi/L | 8 | 2.2× over |
| 98 | Shanor-Northvue, Pennsylvania | 8.9 pCi/L | 12 | 2.2× over |
| 99 | Boonville, Indiana | 8.9 pCi/L | 7 | 2.2× over |
| 100 | Eagle, Nebraska | 8.8 pCi/L | 8 | 2.2× over |