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	59542	Turner	MT	Zone 1 (High)	22/100
2	59484	Sweet Grass	MT	Zone 1 (High)	28/100
3	59003	Ashland	MT	Zone 1 (High)	33/100
4	59004	Ashland	MT	Zone 1 (High)	33/100
5	59035	Fort Smith	MT	Zone 1 (High)	33/100
6	59858	Philipsburg	MT	Zone 1 (High)	33/100
7	59648	Wolf Creek	MT	Zone 1 (High)	34/100
8	59602	Helena	MT	Zone 1 (High)	37/100
9	59620	Helena	MT	Zone 1 (High)	37/100
10	59623	Helena	MT	Zone 1 (High)	37/100
11	59624	Helena	MT	Zone 1 (High)	37/100
12	59625	Helena	MT	Zone 1 (High)	37/100
13	59626	Helena	MT	Zone 1 (High)	37/100
14	59230	Glasgow	MT	Zone 1 (High)	39/100
15	59007	Bearcreek	MT	Zone 1 (High)	40/100
16	59016	Busby	MT	Zone 1 (High)	40/100
17	59022	Crow Agency	MT	Zone 1 (High)	40/100
18	59025	Decker	MT	Zone 1 (High)	40/100
19	59031	Garryowen	MT	Zone 1 (High)	40/100
20	59043	Lame Deer	MT	Zone 1 (High)	40/100
21	59062	Otter	MT	Zone 1 (High)	40/100
22	59066	Pryor	MT	Zone 1 (High)	40/100
23	59077	Sand Springs	MT	Zone 1 (High)	40/100
24	59084	Teigen	MT	Zone 1 (High)	40/100
25	59089	Wyola	MT	Zone 1 (High)	40/100
26	59213	Brockton	MT	Zone 1 (High)	40/100
27	59214	Brockway	MT	Zone 1 (High)	40/100
28	59217	Crane	MT	Zone 1 (High)	40/100
29	59219	Dagmar	MT	Zone 1 (High)	40/100
30	59225	Frazer	MT	Zone 1 (High)	40/100
31	59240	Glentana	MT	Zone 1 (High)	40/100
32	59242	Homestead	MT	Zone 1 (High)	40/100
33	59244	Larslan	MT	Zone 1 (High)	40/100
34	59253	Peerless	MT	Zone 1 (High)	40/100
35	59256	Raymond	MT	Zone 1 (High)	40/100
36	59257	Redstone	MT	Zone 1 (High)	40/100
37	59258	Reserve	MT	Zone 1 (High)	40/100
38	59260	Richland	MT	Zone 1 (High)	40/100
39	59262	Savage	MT	Zone 1 (High)	40/100
40	59273	Vandalia	MT	Zone 1 (High)	40/100
41	59274	Vida	MT	Zone 1 (High)	40/100
42	59276	Whitetail	MT	Zone 1 (High)	40/100
43	59311	Alzada	MT	Zone 1 (High)	40/100
44	59312	Angela	MT	Zone 1 (High)	40/100
45	59314	Biddle	MT	Zone 1 (High)	40/100
46	59315	Bloomfield	MT	Zone 1 (High)	40/100
47	59316	Boyes	MT	Zone 1 (High)	40/100
48	59318	Brusett	MT	Zone 1 (High)	40/100
49	59319	Capitol	MT	Zone 1 (High)	40/100
50	59322	Cohagen	MT	Zone 1 (High)	40/100
51	59326	Fallon	MT	Zone 1 (High)	40/100
52	59332	Hammond	MT	Zone 1 (High)	40/100
53	59333	Hathaway	MT	Zone 1 (High)	40/100
54	59336	Ismay	MT	Zone 1 (High)	40/100
55	59339	Lindsay	MT	Zone 1 (High)	40/100
56	59341	Mildred	MT	Zone 1 (High)	40/100
57	59343	Olive	MT	Zone 1 (High)	40/100
58	59345	Powderville	MT	Zone 1 (High)	40/100
59	59349	Terry	MT	Zone 1 (High)	40/100
60	59351	Volborg	MT	Zone 1 (High)	40/100
61	59354	Willard	MT	Zone 1 (High)	40/100
62	59402	Malmstrom A F B	MT	Zone 1 (High)	40/100
63	59418	Buffalo	MT	Zone 1 (High)	40/100
64	59424	Coffee Creek	MT	Zone 1 (High)	40/100
65	59432	Dupuyer	MT	Zone 1 (High)	40/100
66	59434	East Glacier Park	MT	Zone 1 (High)	40/100
67	59440	Floweree	MT	Zone 1 (High)	40/100
68	59441	Forest Grove	MT	Zone 1 (High)	40/100
69	59448	Heart Butte	MT	Zone 1 (High)	40/100
70	59451	Hilger	MT	Zone 1 (High)	40/100
71	59457	Lewistown	MT	Zone 1 (High)	40/100
72	59461	Lothair	MT	Zone 1 (High)	40/100
73	59462	Moccasin	MT	Zone 1 (High)	40/100
74	59466	Oilmont	MT	Zone 1 (High)	40/100
75	59469	Raynesford	MT	Zone 1 (High)	40/100
76	59521	Box Elder	MT	Zone 1 (High)	40/100
77	59526	Harlem	MT	Zone 1 (High)	40/100
78	59527	Hays	MT	Zone 1 (High)	40/100
79	59529	Hogeland	MT	Zone 1 (High)	40/100
80	59530	Inverness	MT	Zone 1 (High)	40/100
81	59531	Joplin	MT	Zone 1 (High)	40/100
82	59532	Kremlin	MT	Zone 1 (High)	40/100
83	59535	Lloyd	MT	Zone 1 (High)	40/100
84	59633	Canyon Creek	MT	Zone 1 (High)	40/100
85	59638	Jefferson City	MT	Zone 1 (High)	40/100
86	59640	Marysville	MT	Zone 1 (High)	40/100
87	59641	Radersburg	MT	Zone 1 (High)	40/100
88	59642	Ringling	MT	Zone 1 (High)	40/100
89	59647	Winston	MT	Zone 1 (High)	40/100
90	59713	Avon	MT	Zone 1 (High)	40/100
91	59720	Cameron	MT	Zone 1 (High)	40/100
92	59727	Divide	MT	Zone 1 (High)	40/100
93	59728	Elliston	MT	Zone 1 (High)	40/100
94	59731	Garrison	MT	Zone 1 (High)	40/100
95	59732	Glen	MT	Zone 1 (High)	40/100
96	59733	Gold Creek	MT	Zone 1 (High)	40/100
97	59735	Harrison	MT	Zone 1 (High)	40/100
98	59740	Mc Allister	MT	Zone 1 (High)	40/100
99	59743	Melrose	MT	Zone 1 (High)	40/100
100	59746	Polaris	MT	Zone 1 (High)	40/100

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: 2026-06-04.

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%.