Is Crook County, WY a radon risk area?

Crook County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Crook County sits at the 74th percentile nationally for radon potential — above 74 of every 100 rated counties.

Crook County by the numbers

About 7,775 people live in Crook County, Wyoming, spread over 2,854.48 square miles. Population density there runs about 3 people per square mile. Rank 824 by population within its EPA zone puts Crook County at the 23rd percentile among zone peers. Geologically, Crook County is grouped into EPA Region 8 alongside 290 other counties that share its rock and soil setting.

What this actually means for a house in Crook County

Crook County's predicted average sits above EPA's own action level of 4 pCi/L — the concentration at which EPA recommends fixing a home — versus a national average around 1.3 pCi/L indoors and 0.4 pCi/L outdoors. A Zone 1 rating means testing is worth doing sooner rather than later, but it is still county-wide average, not a reading for any single house — some homes in Crook County will test well under the action level, and EPA's guidance is to test regardless of zone.

Testing and mitigation in Crook County

Nothing about Crook County's EPA zone changes the mitigation number: $800–$2,500 nationally (around $1,200 typical), set by the house's foundation rather than the county it sits in — and only relevant once a test actually clears 4 pCi/L.

Find Wyoming's state radon program

Crook County's test kit answers today; a Airthings radon monitor keeps answering for Crook County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. Use code RADONZONE-10OFF at checkout for 10% off.

More on how this number was built

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. Whatever zone Crook County carries, the zone explainer covers what it does and doesn't tell you about any one house.