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

EPA places Logan County in Zone 1 - Highest Potential — a predicted county-wide average indoor radon level above 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. That puts Logan County in the 82nd percentile nationally for radon potential — higher than 82% of the counties EPA has rated.

Where Logan County sits nationally

Logan County, Colorado is home to about 20,755 people across 1,838.599 square miles. Population density there runs about 11 people per square mile. By population, Logan County is the 564th largest of every county sharing its EPA zone — the 47th percentile by population within that zone. Geologically, Logan County is grouped into EPA Region 8 alongside 290 other counties that share its rock and soil setting.

Zone vs. an actual test

Logan 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. Being in Zone 1 raises the odds Logan County homes test above the action level, but it does not mean any specific house does — EPA recommends every home be tested, in every zone, because the only way to know is to test.

If Logan County tests above the action level

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

Where Logan 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. Whatever zone Logan County carries, the zone explainer covers what it does and doesn't tell you about any one house.