Cheyenne County, CO: EPA's radon zone, explained

EPA's own radon map rates Cheyenne County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. That puts Cheyenne County in the 67th percentile nationally for radon potential — higher than 67% of the counties EPA has rated.

Where Cheyenne County sits nationally

Cheyenne County, Colorado is home to about 1,712 people across 1,778.276 square miles. Population density there runs about 1 people per square mile. By population, Cheyenne County is the 1042nd largest of every county sharing its EPA zone — the 2nd percentile by population within that zone. Geologically, Cheyenne County is grouped into EPA Region 8 alongside 290 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

Cheyenne County carries a Zone 1 label because its predicted average clears 4 pCi/L outright — three-plus times the 0.4 pCi/L typical outdoors and above the 1.3 pCi/L most homes see. That doesn't mean every Cheyenne County house tests high — a zone is a county-wide prediction, never a single-home reading — but it's a reason to test sooner rather than let it wait.

Next steps for a home in Cheyenne County

For a Cheyenne County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.

Find Colorado's state radon program

For Cheyenne County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Cheyenne County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. Use code RADONZONE-10OFF at checkout for 10% off.

Where Cheyenne County's figures come from

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.