Is Polk County, IA a radon risk area?

Polk County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. That puts Polk County in the 99th percentile nationally for radon potential — higher than 99% of the counties EPA has rated.

Where Polk County sits nationally

About 516,185 people live in Polk County, Iowa, spread over 572.72 square miles. That works out to roughly 901 people per square mile. Rank 44 by population within its EPA zone puts Polk County at the 96th percentile among zone peers. Geologically, Polk County is grouped into EPA Region 7 alongside 411 other counties that share its rock and soil setting.

What this actually means for a house in Polk County

Where the national indoor average runs about 1.3 pCi/L, Polk County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. Being in Zone 1 raises the odds Polk County homes test above the action level, but it does not mean any specific house does — EPA recommends every home be tested, in every zone, because the only way to know is to test.

Next steps for a home in Polk County

Nothing about Polk 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

Polk County's test kit answers today; a Airthings radon monitor keeps answering for Polk 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. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.