Colorado Cities Ranked by Indoor Radon Levels
Measured averages from Airthings devices across Colorado, USA. Action level: 4 pCi/L — the threshold at which remediation is recommended.
Idaho Springs has the highest measured indoor radon in Colorado at 10.4 pCi/L, based on Airthings measurements across 160 cities.
Updated October 19, 2026
Highest city
10.4pCi/L
Idaho Springs
Colorado city average
3.8pCi/L
across 160 cities
Above action level
55/ 160
cities
| # | Location | Avg level | vs action level |
|---|---|---|---|
| 1 | Idaho Springs | 10.4 pCi/L | 2.6× over |
| 2 | Trinidad | 8.5 pCi/L | 2.1× over |
| 3 | Platteville | 8.2 pCi/L | 2.0× over |
| 4 | Minturn | 7.7 pCi/L | 1.9× over |
| 5 | Keystone | 7.0 pCi/L | 1.8× over |
| 6 | Cripple Creek | 7.0 pCi/L | 1.7× over |
| 7 | Colorado City | 6.9 pCi/L | 1.7× over |
| 8 | Coal Creek | 6.7 pCi/L | 1.7× over |
| 9 | Canon City | 6.4 pCi/L | 1.6× over |
| 10 | Leadville | 6.3 pCi/L | 1.6× over |
| 11 | Palmer Lake | 6.3 pCi/L | 1.6× over |
| 12 | Estes Park | 6.3 pCi/L | 1.6× over |
| 13 | Pueblo | 6.2 pCi/L | 1.6× over |
| 14 | Bennett | 5.9 pCi/L | 1.5× over |
| 15 | Fort Morgan | 5.8 pCi/L | 1.4× over |
| 16 | Granby | 5.7 pCi/L | 1.4× over |
| 17 | Mountain Village | 5.6 pCi/L | 1.4× over |
| 18 | Milliken | 5.4 pCi/L | 1.4× over |
| 19 | Southglenn | 5.3 pCi/L | 1.3× over |
| 20 | Campion | 5.3 pCi/L | 1.3× over |
| 21 | Columbine Valley | 5.2 pCi/L | 1.3× over |
| 22 | Pueblo West | 5.1 pCi/L | 1.3× over |
| 23 | Laporte | 5.1 pCi/L | 1.3× over |
| 24 | Lochbuie | 5.1 pCi/L | 1.3× over |
| 25 | Manitou Springs | 5.1 pCi/L | 1.3× over |
| 26 | Gypsum | 5.1 pCi/L | 1.3× over |
| 27 | Fraser | 5.0 pCi/L | 1.3× over |
| 28 | Woodland Park | 5.0 pCi/L | 1.3× over |
| 29 | Wellington | 5.0 pCi/L | 1.3× over |
| 30 | Stratmoor | 5.0 pCi/L | 1.2× over |
| 31 | Silverthorne | 4.8 pCi/L | 1.2× over |
| 32 | Grand Junction | 4.7 pCi/L | 1.2× over |
| 33 | Durango | 4.6 pCi/L | 1.2× over |
| 34 | Ellicott | 4.6 pCi/L | 1.2× over |
| 35 | Indian Hills | 4.6 pCi/L | 1.1× over |
| 36 | Westcliffe | 4.5 pCi/L | 1.1× over |
| 37 | Burlington | 4.5 pCi/L | 1.1× over |
| 38 | Leadville North | 4.5 pCi/L | 1.1× over |
| 39 | New Castle | 4.5 pCi/L | 1.1× over |
| 40 | Ponderosa Park | 4.4 pCi/L | 1.1× over |
| 41 | Johnstown | 4.3 pCi/L | 1.1× over |
| 42 | Gunnison | 4.3 pCi/L | 1.1× over |
| 43 | Paonia | 4.2 pCi/L | 1.1× over |
| 44 | Breckenridge | 4.2 pCi/L | 1.1× over |
| 45 | Dacono | 4.2 pCi/L | 1.1× over |
| 46 | Berthoud | 4.2 pCi/L | 1.1× over |
| 47 | Central City | 4.2 pCi/L | 1.0× over |
| 48 | Littleton | 4.2 pCi/L | 1.0× over |
| 49 | Palisade | 4.1 pCi/L | 1.0× over |
| 50 | Westminster | 4.1 pCi/L | 1.0× over |
| 51 | Cherry Hills Village | 4.1 pCi/L | 1.0× over |
| 52 | Evergreen | 4.1 pCi/L | 1.0× over |
| 53 | Crested Butte | 4.0 pCi/L | 1.0× over |
| 54 | Colorado Springs | 4.0 pCi/L | 1.0× over |
| 55 | Loveland | 4.0 pCi/L | 1.0× over |
| ✓ Below EPA action level (4 pCi/L) | |||
| 56 | Ken Caryl | 4.0 pCi/L | 1.0× under |
| 57 | Fountain | 4.0 pCi/L | 1.0× under |
| 58 | Woodmoor | 3.9 pCi/L | 1.0× under |
| 59 | Elizabeth | 3.9 pCi/L | 1.0× under |
| 60 | Greenwood Village | 3.9 pCi/L | 1.0× under |
| 61 | Perry Park | 3.9 pCi/L | 1.0× under |
| 62 | Lakewood | 3.9 pCi/L | 1.0× under |
| 63 | Columbine | 3.9 pCi/L | 1.0× under |
| 64 | Edwards | 3.9 pCi/L | 1.0× under |
| 65 | Montrose | 3.9 pCi/L | 1.0× under |
| 66 | Castlewood | 3.9 pCi/L | 1.0× under |
| 67 | Carbondale | 3.9 pCi/L | 1.0× under |
| 68 | Arvada | 3.8 pCi/L | 1.0× under |
| 69 | Todd Creek | 3.8 pCi/L | 1.0× under |
| 70 | Black Forest | 3.8 pCi/L | 0.9× under |
| 71 | Lake City | 3.7 pCi/L | 0.9× under |
| 72 | Castle Rock | 3.7 pCi/L | 0.9× under |
| 73 | Firestone | 3.7 pCi/L | 0.9× under |
| 74 | Buena Vista | 3.7 pCi/L | 0.9× under |
| 75 | Acres Green | 3.6 pCi/L | 0.9× under |
| 76 | Fort Carson | 3.6 pCi/L | 0.9× under |
| 77 | West Pleasant View | 3.6 pCi/L | 0.9× under |
| 78 | Aurora | 3.6 pCi/L | 0.9× under |
| 79 | Monument | 3.6 pCi/L | 0.9× under |
| 80 | Pagosa Springs | 3.6 pCi/L | 0.9× under |
| 81 | Brighton | 3.5 pCi/L | 0.9× under |
| 82 | Wheat Ridge | 3.5 pCi/L | 0.9× under |
| 83 | Applewood | 3.5 pCi/L | 0.9× under |
| 84 | Frisco | 3.5 pCi/L | 0.9× under |
| 85 | Keenesburg | 3.5 pCi/L | 0.9× under |
| 86 | Lyons | 3.5 pCi/L | 0.9× under |
| 87 | Georgetown | 3.5 pCi/L | 0.9× under |
| 88 | Salida | 3.4 pCi/L | 0.9× under |
| 89 | Windsor | 3.4 pCi/L | 0.9× under |
| 90 | Fort Collins | 3.4 pCi/L | 0.8× under |
| 91 | Centennial | 3.4 pCi/L | 0.8× under |
| 92 | Edgewater | 3.4 pCi/L | 0.8× under |
| 93 | Glendale | 3.4 pCi/L | 0.8× under |
| 94 | Twin Lakes | 3.4 pCi/L | 0.8× under |
| 95 | Roxborough Park | 3.4 pCi/L | 0.8× under |
| 96 | Thornton | 3.4 pCi/L | 0.8× under |
| 97 | Longmont | 3.3 pCi/L | 0.8× under |
| 98 | Carriage Club | 3.3 pCi/L | 0.8× under |
| 99 | Greeley | 3.3 pCi/L | 0.8× under |
| 100 | Highlands Ranch | 3.3 pCi/L | 0.8× under |
| 101 | Steamboat Springs | 3.3 pCi/L | 0.8× under |
| 102 | Broomfield | 3.3 pCi/L | 0.8× under |
| 103 | Mead | 3.3 pCi/L | 0.8× under |
| 104 | Northglenn | 3.3 pCi/L | 0.8× under |
| 105 | Castle Pines North | 3.3 pCi/L | 0.8× under |
| 106 | Englewood | 3.2 pCi/L | 0.8× under |
| 107 | Sheridan | 3.2 pCi/L | 0.8× under |
| 108 | Cascade-Chipita Park | 3.2 pCi/L | 0.8× under |
| 109 | Lafayette | 3.2 pCi/L | 0.8× under |
| 110 | Air Force Academy | 3.2 pCi/L | 0.8× under |
| 111 | Mancos | 3.1 pCi/L | 0.8× under |
| 112 | Parker | 3.0 pCi/L | 0.7× under |
| 113 | Erie | 3.0 pCi/L | 0.7× under |
| 114 | The Pinery | 3.0 pCi/L | 0.7× under |
| 115 | Security-Widefield | 3.0 pCi/L | 0.7× under |
| 116 | Bayfield | 2.9 pCi/L | 0.7× under |
| 117 | Nederland | 2.9 pCi/L | 0.7× under |
| 118 | Clifton | 2.9 pCi/L | 0.7× under |
| 119 | Stonegate | 2.9 pCi/L | 0.7× under |
| 120 | Boulder | 2.9 pCi/L | 0.7× under |
| 121 | Kittredge | 2.9 pCi/L | 0.7× under |
| 122 | Fairplay | 2.9 pCi/L | 0.7× under |
| 123 | Commerce City | 2.9 pCi/L | 0.7× under |
| 124 | Gunbarrel | 2.9 pCi/L | 0.7× under |
| 125 | Niwot | 2.8 pCi/L | 0.7× under |
| 126 | Dove Valley | 2.8 pCi/L | 0.7× under |
| 127 | Eagle | 2.8 pCi/L | 0.7× under |
| 128 | Redlands | 2.8 pCi/L | 0.7× under |
| 129 | Gleneagle | 2.8 pCi/L | 0.7× under |
| 130 | Denver | 2.8 pCi/L | 0.7× under |
| 131 | Fort Lupton | 2.7 pCi/L | 0.7× under |
| 132 | Severance | 2.7 pCi/L | 0.7× under |
| 133 | Cimarron Hills | 2.7 pCi/L | 0.7× under |
| 134 | Castle Pines | 2.7 pCi/L | 0.7× under |
| 135 | El Jebel | 2.7 pCi/L | 0.7× under |
| 136 | Genesee | 2.7 pCi/L | 0.7× under |
| 137 | Kiowa | 2.6 pCi/L | 0.6× under |
| 138 | Golden | 2.6 pCi/L | 0.6× under |
| 139 | Cortez | 2.5 pCi/L | 0.6× under |
| 140 | Silt | 2.5 pCi/L | 0.6× under |
| 141 | Lone Tree | 2.5 pCi/L | 0.6× under |
| 142 | Louisville | 2.5 pCi/L | 0.6× under |
| 143 | Ouray | 2.5 pCi/L | 0.6× under |
| 144 | Superior | 2.5 pCi/L | 0.6× under |
| 145 | Telluride | 2.3 pCi/L | 0.6× under |
| 146 | Silverton | 2.3 pCi/L | 0.6× under |
| 147 | La Junta | 2.2 pCi/L | 0.6× under |
| 148 | Aspen | 2.2 pCi/L | 0.5× under |
| 149 | Glenwood Springs | 2.1 pCi/L | 0.5× under |
| 150 | Derby | 2.1 pCi/L | 0.5× under |
| 151 | Frederick | 2.0 pCi/L | 0.5× under |
| 152 | Federal Heights | 2.0 pCi/L | 0.5× under |
| 153 | Berkley | 2.0 pCi/L | 0.5× under |
| 154 | Snowmass Village | 2.0 pCi/L | 0.5× under |
| 155 | Fruitvale | 1.9 pCi/L | 0.5× under |
| 156 | Basalt | 1.8 pCi/L | 0.5× under |
| 157 | Fruita | 1.8 pCi/L | 0.4× under |
| 158 | Vail | 1.7 pCi/L | 0.4× under |
| 159 | Orchard Mesa | 1.6 pCi/L | 0.4× under |
| 160 | Avon | 1.5 pCi/L | 0.4× under |