What EPA's radon map says about McDonald County

EPA's own radon map rates McDonald County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. McDonald County sits at the 48th percentile nationally for radon potential — above 48 of every 100 rated counties.

Where McDonald County sits nationally

About 24,054 people live in McDonald County, Missouri, spread over 539.445 square miles. Averaged across its land area, McDonald County runs about 45 people per square mile. Among counties sharing McDonald County's EPA zone, it outranks 45% of them by population. Geologically, McDonald County is grouped into EPA Region 7 alongside 411 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

Call it a middle case: above the 1.3 pCi/L most US homes average, below the 4 pCi/L line EPA uses to recommend mitigation — that's McDonald County's Zone 2 prediction. A county-wide moderate average, like McDonald County's, can still hide a specific house well above or below it — testing is what actually answers the question.

If McDonald County tests above the action level

Mitigation cost doesn't depend on McDonald 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

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

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. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.