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

Douglas 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, Douglas County ranks higher in radon potential than 41% of rated counties (the 41st percentile).

How Douglas County compares

Douglas County, Missouri is home to about 12,290 people across 813.623 square miles. Population density there runs about 15 people per square mile. By population, Douglas County is the 778th largest of every county sharing its EPA zone — the 25th percentile by population within that zone. Geologically, Douglas 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

Douglas 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). Middle-of-the-pack doesn't mean risk-free for any one Douglas County address — a moderate county average still leaves individual homes to test either side of it.

Next steps for a home in Douglas County

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

Where Douglas 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. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.