What EPA's radon map says about McLean County

McLean County is mapped as Zone 2 - Moderate Potential by EPA — meaning the county-wide average indoor level is predicted between 2 and 4 pCi/L. Nationally, McLean County ranks higher in radon potential than 39% of rated counties (the 39th percentile).

Where McLean County sits nationally

About 9,126 people live in McLean County, Kentucky, spread over 252.525 square miles. That works out to roughly 36 people per square mile. Among counties sharing McLean County's EPA zone, it outranks 19% of them by population. EPA's geology-based Region 4 groups McLean County with 735 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in McLean County

EPA's Zone 2 rating for McLean County sits below its own 4 pCi/L action level but above the national indoor average of about 1.3 pCi/L. Middle-of-the-pack doesn't mean risk-free for any one McLean County address — a moderate county average still leaves individual homes to test either side of it.

If McLean County tests above the action level

Mitigation cost doesn't depend on McLean 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

McLean County's test kit answers today; a Airthings radon monitor keeps answering for McLean 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 McLean County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.