What EPA's radon map says about Sublette County

Sublette County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Nationally, Sublette County ranks higher in radon potential than 75% of rated counties (the 75th percentile).

Sublette County by the numbers

About 8,965 people live in Sublette County, Wyoming, spread over 4,886.482 square miles. Averaged across its land area, Sublette County runs about 2 people per square mile. Among counties sharing Sublette County's EPA zone, it outranks 25% of them by population. Geologically, Sublette 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

Sublette 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. EPA's guidance doesn't change because of a Zone 1 label: test the house. What changes is the reason to not put it off in Sublette County specifically.

Testing and mitigation in Sublette County

Mitigation cost doesn't depend on Sublette County's zone — it depends on the house's foundation. A typical system runs $800–$2,500 (about $1,200 typical), and testing first is what tells you whether that's needed at all.

Find Wyoming's state radon program

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

More on how this number was built

The methodology guide shows exactly which EPA and Census sources feed Sublette County's numbers. Whatever zone Sublette County carries, the zone explainer covers what it does and doesn't tell you about any one house.