Radon Levels in Colorado
64 counties — 53 high risk, 11 moderate, 0 low risk
Colorado Radon Zone Map
Counties colored by EPA radon zone. Red = Zone 1, Orange = Zone 2, Green = Zone 3.
Highest-Risk Counties
Adams47.1% above action level
Arapahoe32.5% above action level
BacaZone 1 — High
BentZone 1 — High
Boulder36.4% above action level
BroomfieldZone 1 — High
ChaffeeZone 1 — High
CheyenneZone 1 — High
Clear CreekZone 1 — High
CrowleyZone 1 — High
CusterZone 1 — High
DeltaZone 1 — High
+41 more
Check Your Colorado ZIP Code
All 64 Counties — By Radon Risk
Sources: EPA Map of Radon Zones, CDC Environmental Health Tracking Network
Frequently Asked Questions
How many counties in Colorado have high radon risk?
Colorado has 53 counties classified as EPA Zone 1 (high radon risk), 11 as Zone 2 (moderate), and 0 as Zone 3 (low risk).
Is radon a problem in Colorado?
Colorado has 53 high-risk counties where elevated radon is likely. The EPA recommends all homes in Colorado be tested for radon, regardless of which zone they're in.
How do I check radon levels for my Colorado 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.