Radon Levels in Montana
56 counties — 49 high risk, 7 moderate, 0 low risk
Montana Radon Zone Map
Counties colored by EPA radon zone. Red = Zone 1, Orange = Zone 2, Green = Zone 3.
Highest-Risk Counties
BeaverheadZone 1 — High
Big HornZone 1 — High
BlaineZone 1 — High
BroadwaterZone 1 — High
CarbonZone 1 — High
CarterZone 1 — High
Cascade30.8% above action level
ChouteauZone 1 — High
CusterZone 1 — High
DanielsZone 1 — High
DawsonZone 1 — High
Deer LodgeZone 1 — High
+37 more
Check Your Montana ZIP Code
All 56 Counties — By Radon Risk
Sources: EPA Map of Radon Zones, CDC Environmental Health Tracking Network
Frequently Asked Questions
How many counties in Montana have high radon risk?
Montana has 49 counties classified as EPA Zone 1 (high radon risk), 7 as Zone 2 (moderate), and 0 as Zone 3 (low risk).
Is radon a problem in Montana?
Montana has 49 high-risk counties where elevated radon is likely. The EPA recommends all homes in Montana be tested for radon, regardless of which zone they're in.
How do I check radon levels for my Montana address?
Enter your ZIP code in the search box above to see your county's EPA radon zone and available testing data. For your specific home's radon level, you'll need a radon test kit.