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 10.8 pCi/L, based on Airthings measurements across 157 cities.

Updated August 16, 2026

Highest city

10.8pCi/L

Idaho Springs

Colorado city average

3.9pCi/L

across 157 cities

Above action level

59/ 157

cities

Colorado Cities Ranked by Indoor Radon Levels
#	Location	Avg level	Monitors	vs action level
1	Idaho Springs	10.8 pCi/L	11	2.7× over
2	Trinidad	9.1 pCi/L	7	2.3× over
3	Platteville	8.2 pCi/L	8	2.0× over
4	Keystone	7.9 pCi/L	14	2.0× over
5	Minturn	7.7 pCi/L	6	1.9× over
6	Cripple Creek	7.0 pCi/L	24	1.7× over
7	Colorado City	6.9 pCi/L	16	1.7× over
8	Coal Creek	6.8 pCi/L	30	1.7× over
9	Leadville	6.5 pCi/L	16	1.6× over
10	Canon City	6.4 pCi/L	8	1.6× over
11	Pueblo	6.3 pCi/L	28	1.6× over
12	Palmer Lake	6.3 pCi/L	12	1.6× over
13	Bennett	6.1 pCi/L	8	1.5× over
14	Estes Park	6.0 pCi/L	69	1.5× over
15	Fort Morgan	6.0 pCi/L	7	1.5× over
16	Granby	5.9 pCi/L	10	1.5× over
17	Campion	5.5 pCi/L	24	1.4× over
18	Milliken	5.4 pCi/L	11	1.4× over
19	Southglenn	5.4 pCi/L	50	1.3× over
20	Mountain Village	5.3 pCi/L	14	1.3× over
21	Lochbuie	5.3 pCi/L	11	1.3× over
22	Manitou Springs	5.3 pCi/L	31	1.3× over
23	Woodland Park	5.2 pCi/L	54	1.3× over
24	Columbine Valley	5.2 pCi/L	29	1.3× over
25	Laporte	5.2 pCi/L	54	1.3× over
26	Gypsum	5.2 pCi/L	11	1.3× over
27	Fraser	5.2 pCi/L	22	1.3× over
28	Silverthorne	5.2 pCi/L	20	1.3× over
29	Wellington	5.1 pCi/L	33	1.3× over
30	Pueblo West	5.1 pCi/L	50	1.3× over
31	Stratmoor	5.0 pCi/L	31	1.3× over
32	Grand Junction	4.8 pCi/L	21	1.2× over
33	Indian Hills	4.8 pCi/L	35	1.2× over
34	Ellicott	4.7 pCi/L	32	1.2× over
35	Durango	4.6 pCi/L	96	1.1× over
36	Westcliffe	4.5 pCi/L	8	1.1× over
37	Burlington	4.5 pCi/L	8	1.1× over
38	Leadville North	4.5 pCi/L	6	1.1× over
39	Johnstown	4.5 pCi/L	22	1.1× over
40	New Castle	4.5 pCi/L	7	1.1× over
41	Breckenridge	4.4 pCi/L	36	1.1× over
42	Palisade	4.4 pCi/L	6	1.1× over
43	Ponderosa Park	4.3 pCi/L	24	1.1× over
44	Berthoud	4.3 pCi/L	32	1.1× over
45	Westminster	4.3 pCi/L	110	1.1× over
46	Gunnison	4.3 pCi/L	17	1.1× over
47	Paonia	4.2 pCi/L	6	1.1× over
48	Littleton	4.2 pCi/L	89	1.1× over
49	Dacono	4.2 pCi/L	11	1.1× over
50	Perry Park	4.2 pCi/L	20	1.1× over
51	Fountain	4.2 pCi/L	10	1.0× over
52	Central City	4.2 pCi/L	15	1.0× over
53	Evergreen	4.1 pCi/L	180	1.0× over
54	Loveland	4.1 pCi/L	135	1.0× over
55	Castlewood	4.1 pCi/L	63	1.0× over
56	Cherry Hills Village	4.0 pCi/L	75	1.0× over
57	Crested Butte	4.0 pCi/L	39	1.0× over
58	Colorado Springs	4.0 pCi/L	254	1.0× over
59	Woodmoor	4.0 pCi/L	49	1.0× over
✓ Below EPA action level (4 pCi/L)
60	Greenwood Village	4.0 pCi/L	46	1.0× under
61	Ken Caryl	4.0 pCi/L	121	1.0× under
62	Columbine	4.0 pCi/L	70	1.0× under
63	Elizabeth	3.9 pCi/L	30	1.0× under
64	Lake City	3.9 pCi/L	11	1.0× under
65	Carbondale	3.9 pCi/L	30	1.0× under
66	Arvada	3.9 pCi/L	163	1.0× under
67	Black Forest	3.9 pCi/L	192	1.0× under
68	Lakewood	3.8 pCi/L	152	1.0× under
69	Castle Rock	3.8 pCi/L	153	0.9× under
70	Buena Vista	3.8 pCi/L	60	0.9× under
71	Acres Green	3.7 pCi/L	18	0.9× under
72	Montrose	3.7 pCi/L	38	0.9× under
73	Todd Creek	3.7 pCi/L	81	0.9× under
74	Firestone	3.7 pCi/L	29	0.9× under
75	Brighton	3.6 pCi/L	76	0.9× under
76	West Pleasant View	3.6 pCi/L	101	0.9× under
77	Salida	3.6 pCi/L	27	0.9× under
78	Fort Carson	3.6 pCi/L	10	0.9× under
79	Wheat Ridge	3.6 pCi/L	35	0.9× under
80	Keenesburg	3.6 pCi/L	11	0.9× under
81	Monument	3.6 pCi/L	41	0.9× under
82	Aurora	3.6 pCi/L	250	0.9× under
83	Frisco	3.6 pCi/L	20	0.9× under
84	Applewood	3.5 pCi/L	104	0.9× under
85	Pagosa Springs	3.5 pCi/L	24	0.9× under
86	Lyons	3.5 pCi/L	19	0.9× under
87	Georgetown	3.5 pCi/L	47	0.9× under
88	Windsor	3.4 pCi/L	142	0.9× under
89	Fort Collins	3.4 pCi/L	281	0.9× under
90	Highlands Ranch	3.4 pCi/L	208	0.8× under
91	Mead	3.4 pCi/L	34	0.8× under
92	Glendale	3.4 pCi/L	303	0.8× under
93	Greeley	3.4 pCi/L	40	0.8× under
94	Roxborough Park	3.4 pCi/L	80	0.8× under
95	Edgewater	3.4 pCi/L	137	0.8× under
96	Carriage Club	3.4 pCi/L	69	0.8× under
97	Centennial	3.4 pCi/L	96	0.8× under
98	Northglenn	3.4 pCi/L	123	0.8× under
99	Twin Lakes	3.4 pCi/L	17	0.8× under
100	Longmont	3.3 pCi/L	175	0.8× under
101	Sheridan	3.3 pCi/L	44	0.8× under
102	Lafayette	3.3 pCi/L	140	0.8× under
103	Broomfield	3.3 pCi/L	224	0.8× under
104	Thornton	3.3 pCi/L	57	0.8× under
105	Englewood	3.3 pCi/L	72	0.8× under
106	Air Force Academy	3.3 pCi/L	62	0.8× under
107	Castle Pines North	3.3 pCi/L	39	0.8× under
108	Steamboat Springs	3.3 pCi/L	71	0.8× under
109	Cascade-Chipita Park	3.2 pCi/L	18	0.8× under
110	Parker	3.0 pCi/L	206	0.8× under
111	The Pinery	3.0 pCi/L	105	0.8× under
112	Bayfield	3.0 pCi/L	25	0.7× under
113	Erie	3.0 pCi/L	157	0.7× under
114	Fairplay	3.0 pCi/L	12	0.7× under
115	Boulder	3.0 pCi/L	442	0.7× under
116	Kittredge	2.9 pCi/L	22	0.7× under
117	Stonegate	2.9 pCi/L	75	0.7× under
118	Commerce City	2.9 pCi/L	37	0.7× under
119	Gunbarrel	2.9 pCi/L	48	0.7× under
120	Nederland	2.9 pCi/L	23	0.7× under
121	Niwot	2.9 pCi/L	79	0.7× under
122	Edwards	2.9 pCi/L	25	0.7× under
123	Dove Valley	2.9 pCi/L	141	0.7× under
124	Security-Widefield	2.9 pCi/L	32	0.7× under
125	Genesee	2.9 pCi/L	27	0.7× under
126	Eagle	2.8 pCi/L	16	0.7× under
127	Denver	2.8 pCi/L	431	0.7× under
128	Redlands	2.8 pCi/L	14	0.7× under
129	Gleneagle	2.8 pCi/L	70	0.7× under
130	Cimarron Hills	2.7 pCi/L	145	0.7× under
131	Fort Lupton	2.7 pCi/L	6	0.7× under
132	Severance	2.7 pCi/L	14	0.7× under
133	Castle Pines	2.7 pCi/L	74	0.7× under
134	Golden	2.6 pCi/L	172	0.6× under
135	Kiowa	2.6 pCi/L	7	0.6× under
136	El Jebel	2.5 pCi/L	16	0.6× under
137	Cortez	2.5 pCi/L	6	0.6× under
138	Louisville	2.5 pCi/L	132	0.6× under
139	Silt	2.5 pCi/L	6	0.6× under
140	Lone Tree	2.5 pCi/L	18	0.6× under
141	Ouray	2.5 pCi/L	13	0.6× under
142	Superior	2.4 pCi/L	204	0.6× under
143	Federal Heights	2.3 pCi/L	7	0.6× under
144	Telluride	2.3 pCi/L	9	0.6× under
145	Snowmass Village	2.3 pCi/L	30	0.6× under
146	Silverton	2.3 pCi/L	9	0.6× under
147	Aspen	2.2 pCi/L	50	0.6× under
148	La Junta	2.2 pCi/L	7	0.6× under
149	Glenwood Springs	2.2 pCi/L	8	0.5× under
150	Derby	2.1 pCi/L	43	0.5× under
151	Frederick	2.0 pCi/L	13	0.5× under
152	Berkley	2.0 pCi/L	100	0.5× under
153	Fruitvale	1.9 pCi/L	9	0.5× under
154	Fruita	1.7 pCi/L	6	0.4× under
155	Vail	1.7 pCi/L	13	0.4× under
156	Basalt	1.6 pCi/L	7	0.4× under
157	Avon	1.5 pCi/L	19	0.4× under

See USA cities ranked by radon level See all States ranked by radon level