Is Decatur County, IA a radon risk area?

Decatur County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Nationally that's the 74th percentile for radon potential — Decatur County outranks 74% of every county EPA has rated.

How Decatur County compares

About 7,656 people live in Decatur County, Iowa, spread over 531.883 square miles. Population density there runs about 14 people per square mile. Rank 827 by population within its EPA zone puts Decatur County at the 22nd percentile among zone peers. Geologically, Decatur 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

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Decatur County's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. Some Decatur County homes will test comfortably under the action level despite the county's Zone 1 rating — the only way to know which kind of home you have is an actual test.

If Decatur County tests above the action level

Nothing about Decatur 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 Iowa's state radon program

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

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. Whatever zone Decatur County carries, the zone explainer covers what it does and doesn't tell you about any one house.