What EPA's radon map says about Monroe County

Monroe 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, Monroe County ranks higher in radon potential than 39% of rated counties (the 39th percentile).

How Monroe County compares

About 8,890 people live in Monroe County, Missouri, spread over 647.64 square miles. That works out to roughly 14 people per square mile. Among counties sharing Monroe County's EPA zone, it outranks 18% of them by population. EPA's geology-based Region 7 groups Monroe County with 411 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Monroe County

Monroe 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). Nothing about a Zone 2 label lowers the case for testing in Monroe County — EPA recommends it in every zone, moderate included.

If Monroe County tests above the action level

Mitigation cost doesn't depend on Monroe 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 Missouri's state radon program

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

Monroe County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.