Miller County, MO: EPA's radon zone, explained

EPA places Miller 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. Miller County sits at the 49th percentile nationally for radon potential — above 49 of every 100 rated counties.

Where Miller County sits nationally

Miller County, Missouri is home to about 25,668 people across 592.582 square miles. That works out to roughly 43 people per square mile. By population, Miller County is the 546th largest of every county sharing its EPA zone — the 47th percentile by population within that zone. Geologically, Miller 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

Miller 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. Miller County's Zone 2 rating sits in the middle nationally; EPA's guidance is unchanged by that — test every home regardless of its zone.

Testing and mitigation in Miller County

For a Miller County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.

Find Missouri's state radon program

For Miller County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Miller County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

Where Miller County's figures come from

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. Whatever zone Miller County carries, the zone explainer covers what it does and doesn't tell you about any one house.