What EPA's radon map says about Ralls County

EPA's own radon map rates Ralls County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. Nationally, Ralls County ranks higher in radon potential than 40% of rated counties (the 40th percentile).

How Ralls County compares

About 10,499 people live in Ralls County, Missouri, spread over 469.793 square miles. That works out to roughly 22 people per square mile. Among counties sharing Ralls County's EPA zone, it outranks 22% of them by population. Geologically, Ralls County is grouped into EPA Region 7 alongside 411 other counties that share its rock and soil setting.

Zone vs. an actual test

Ralls County's Zone 2 prediction clears the 1.3 pCi/L national indoor average without reaching EPA's own 4 pCi/L point for recommending a fix. A county-wide moderate average, like Ralls 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 Ralls County

Mitigation cost doesn't depend on Ralls 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

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

Ralls County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. Whatever zone Ralls County carries, the zone explainer covers what it does and doesn't tell you about any one house.