Is Callaway County, MO a radon risk area?

EPA places Callaway County in Zone 2 - Moderate Potential — a predicted county-wide average indoor radon level between 2 and 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Rank it against the rest of the country and Callaway County lands in the 54th percentile for radon potential.

How Callaway County compares

About 45,126 people live in Callaway County, Missouri, spread over 834.565 square miles. Population density there runs about 54 people per square mile. Rank 367 by population within its EPA zone puts Callaway County at the 65th percentile among zone peers. Geologically, Callaway County is grouped into EPA Region 7 alongside 411 other counties that share its rock and soil setting.

Zone vs. an actual test

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 Callaway County's Zone 2 prediction. A county-wide moderate average, like Callaway 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 Callaway County

Nothing about Callaway County's EPA zone changes the mitigation number: $800–$2,500 nationally (around $1,200 typical), set by the house's foundation rather than the county it sits in — and only relevant once a test actually clears 4 pCi/L.

Find Missouri's state radon program

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

The methodology guide shows exactly which EPA and Census sources feed Callaway County's numbers. Whatever zone Callaway County carries, the zone explainer covers what it does and doesn't tell you about any one house.