Highest Radon Risk ZIP Codes in Montana — 2026

Out of 355 ZIP codes with data in Montana, these are the lowest-ranked areas for radon zone. See also: National ZIP Codes with Highest Radon Risk | All Montana Rankings

Statistic	Value
ZIP codes ranked	355
Lowest value	Zone 1 (High)
Median value	Zone 1 (High)
State	Montana

100 Lowest-Ranked ZIP Codes

Rank	ZIP Code	City	State	Radon Zone	Safety Score
1	59901	Kalispell	MT	Zone 1 (High)	35/100
2	59602	Helena	MT	Zone 1 (High)	50/100
3	59937	Whitefish	MT	Zone 1 (High)	50/100
4	59601	Helena	MT	Zone 1 (High)	51/100
5	59923	Libby	MT	Zone 1 (High)	57/100
6	59912	Columbia Falls	MT	Zone 1 (High)	59/100
7	59808	Missoula	MT	Zone 1 (High)	60/100
8	59714	Belgrade	MT	Zone 1 (High)	63/100
9	59860	Polson	MT	Zone 1 (High)	63/100
10	59301	Miles City	MT	Zone 1 (High)	65/100
11	59501	Havre	MT	Zone 1 (High)	65/100
12	59801	Missoula	MT	Zone 1 (High)	65/100
13	59330	Glendive	MT	Zone 1 (High)	66/100
14	59457	Lewistown	MT	Zone 1 (High)	66/100
15	59701	Butte	MT	Zone 1 (High)	66/100
16	59715	Bozeman	MT	Zone 1 (High)	66/100
17	59716	Big Sky	MT	Zone 1 (High)	66/100
18	59718	Bozeman	MT	Zone 1 (High)	66/100
19	59727	Divide	MT	Zone 1 (High)	66/100
20	59802	Missoula	MT	Zone 1 (High)	66/100
21	59803	Missoula	MT	Zone 1 (High)	66/100
22	59270	Sidney	MT	Zone 1 (High)	67/100
23	59725	Dillon	MT	Zone 1 (High)	67/100
24	59812	Missoula	MT	Zone 1 (High)	67/100
25	59834	Frenchtown	MT	Zone 1 (High)	67/100
26	59840	Hamilton	MT	Zone 1 (High)	67/100
27	59911	Bigfork	MT	Zone 1 (High)	67/100
28	59001	Absarokee	MT	Zone 1 (High)	—
29	59002	Acton	MT	Zone 1 (High)	—
30	59003	Ashland	MT	Zone 1 (High)	—
31	59004	Ashland	MT	Zone 1 (High)	—
32	59007	Bearcreek	MT	Zone 1 (High)	—
33	59008	Belfry	MT	Zone 1 (High)	—
34	59012	Birney	MT	Zone 1 (High)	—
35	59013	Boyd	MT	Zone 1 (High)	—
36	59014	Bridger	MT	Zone 1 (High)	—
37	59016	Busby	MT	Zone 1 (High)	—
38	59018	Clyde Park	MT	Zone 1 (High)	—
39	59019	Columbus	MT	Zone 1 (High)	—
40	59020	Cooke City	MT	Zone 1 (High)	—
41	59022	Crow Agency	MT	Zone 1 (High)	—
42	59025	Decker	MT	Zone 1 (High)	—
43	59026	Edgar	MT	Zone 1 (High)	—
44	59027	Emigrant	MT	Zone 1 (High)	—
45	59028	Fishtail	MT	Zone 1 (High)	—
46	59029	Fromberg	MT	Zone 1 (High)	—
47	59030	Gardiner	MT	Zone 1 (High)	—
48	59031	Garryowen	MT	Zone 1 (High)	—
49	59032	Grass Range	MT	Zone 1 (High)	—
50	59034	Hardin	MT	Zone 1 (High)	—
51	59035	Fort Smith	MT	Zone 1 (High)	—
52	59041	Joliet	MT	Zone 1 (High)	—
53	59043	Lame Deer	MT	Zone 1 (High)	—
54	59047	Livingston	MT	Zone 1 (High)	—
55	59050	Lodge Grass	MT	Zone 1 (High)	—
56	59053	Martinsdale	MT	Zone 1 (High)	—
57	59061	Nye	MT	Zone 1 (High)	—
58	59062	Otter	MT	Zone 1 (High)	—
59	59065	Pray	MT	Zone 1 (High)	—
60	59066	Pryor	MT	Zone 1 (High)	—
61	59067	Rapelje	MT	Zone 1 (High)	—
62	59068	Red Lodge	MT	Zone 1 (High)	—
63	59070	Roberts	MT	Zone 1 (High)	—
64	59071	Roscoe	MT	Zone 1 (High)	—
65	59077	Sand Springs	MT	Zone 1 (High)	—
66	59081	Silver Gate	MT	Zone 1 (High)	—
67	59084	Teigen	MT	Zone 1 (High)	—
68	59086	Wilsall	MT	Zone 1 (High)	—
69	59089	Wyola	MT	Zone 1 (High)	—
70	59201	Wolf Point	MT	Zone 1 (High)	—
71	59211	Antelope	MT	Zone 1 (High)	—
72	59212	Bainville	MT	Zone 1 (High)	—
73	59213	Brockton	MT	Zone 1 (High)	—
74	59214	Brockway	MT	Zone 1 (High)	—
75	59215	Circle	MT	Zone 1 (High)	—
76	59217	Crane	MT	Zone 1 (High)	—
77	59218	Culbertson	MT	Zone 1 (High)	—
78	59219	Dagmar	MT	Zone 1 (High)	—
79	59221	Fairview	MT	Zone 1 (High)	—
80	59222	Flaxville	MT	Zone 1 (High)	—
81	59223	Fort Peck	MT	Zone 1 (High)	—
82	59225	Frazer	MT	Zone 1 (High)	—
83	59226	Froid	MT	Zone 1 (High)	—
84	59230	Glasgow	MT	Zone 1 (High)	—
85	59231	Saint Marie	MT	Zone 1 (High)	—
86	59240	Glentana	MT	Zone 1 (High)	—
87	59241	Hinsdale	MT	Zone 1 (High)	—
88	59242	Homestead	MT	Zone 1 (High)	—
89	59243	Lambert	MT	Zone 1 (High)	—
90	59244	Larslan	MT	Zone 1 (High)	—
91	59247	Medicine Lake	MT	Zone 1 (High)	—
92	59248	Nashua	MT	Zone 1 (High)	—
93	59250	Opheim	MT	Zone 1 (High)	—
94	59252	Outlook	MT	Zone 1 (High)	—
95	59253	Peerless	MT	Zone 1 (High)	—
96	59254	Plentywood	MT	Zone 1 (High)	—
97	59255	Poplar	MT	Zone 1 (High)	—
98	59256	Raymond	MT	Zone 1 (High)	—
99	59257	Redstone	MT	Zone 1 (High)	—
100	59258	Reserve	MT	Zone 1 (High)	—

Methodology

Radon rankings are based on EPA county-level radon zone classifications. Zone 1 (highest risk) has predicted average indoor radon levels above 4 pCi/L — the EPA action level. Zone 2 is moderate (2-4 pCi/L) and Zone 3 is low (below 2 pCi/L). Within Zone 1, ZIP codes are sub-ranked by Home Safety Score to prioritize areas with compounding risk factors.

Data sources: EPA Safe Drinking Water Information System (SDWIS), FEMA National Flood Insurance Program, EPA radon zone maps, EIA electricity rates, and Consumer Confidence Reports. Last updated: 2026-08-14.

Frequently Asked Questions

What is EPA Radon Zone 1?

Zone 1 is the EPA highest-risk classification, meaning the county has predicted average indoor radon levels above 4 pCi/L — the level at which the EPA recommends mitigation. Radon causes about 21,000 lung cancer deaths per year in the U.S.

Should I test for radon?

The EPA recommends testing all homes regardless of radon zone. A DIY test kit costs $15-40. Professional testing costs $150-250. If levels exceed 4 pCi/L, mitigation systems ($800-2,500) can reduce radon by up to 99%.