What EPA's radon map says about Spencer County

EPA's own radon map rates Spencer County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. Rank it against the rest of the country and Spencer County lands in the 46th percentile for radon potential.

Where Spencer County sits nationally

About 20,823 people live in Spencer County, Kentucky, spread over 186.671 square miles. That works out to roughly 112 people per square mile. Among counties sharing Spencer County's EPA zone, it outranks 41% of them by population. Geologically, Spencer County is grouped into EPA Region 4 alongside 735 other counties that share its rock and soil setting.

What this actually means for a house in Spencer County

Spencer County's predicted average falls between EPA's 4 pCi/L action level and the national indoor average of about 1.3 pCi/L (outdoor air runs roughly 0.4 pCi/L). A county-wide moderate average, like Spencer County's, can still hide a specific house well above or below it — testing is what actually answers the question.

Next steps for a home in Spencer County

Mitigation cost doesn't depend on Spencer 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 Kentucky's state radon program

Spencer County's test kit answers today; a Airthings radon monitor keeps answering for Spencer 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

The methodology guide shows exactly which EPA and Census sources feed Spencer County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.