Is Monroe County, IA a radon risk area?

Monroe 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 Monroe County in the 73rd percentile nationally for radon potential — higher than 73% of the counties EPA has rated.

Monroe County by the numbers

About 7,373 people live in Monroe County, Iowa, spread over 433.708 square miles. Averaged across its land area, Monroe County runs about 17 people per square mile. Rank 835 by population within its EPA zone puts Monroe County at the 22nd percentile among zone peers. Geologically, Monroe County is grouped into EPA Region 7 alongside 411 other counties that share its rock and soil setting.

Zone vs. an actual test

Monroe County carries a Zone 1 label because its predicted average clears 4 pCi/L outright — three-plus times the 0.4 pCi/L typical outdoors and above the 1.3 pCi/L most homes see. EPA's guidance doesn't change because of a Zone 1 label: test the house. What changes is the reason to not put it off in Monroe County specifically.

If Monroe County tests above the action level

Nothing about Monroe 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

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

The methodology guide shows exactly which EPA and Census sources feed Monroe County's numbers. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.