Is Clay County, MN a radon risk area?

Clay 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 Clay County in the 92nd percentile nationally for radon potential — higher than 92% of the counties EPA has rated.

Where Clay County sits nationally

About 66,848 people live in Clay County, Minnesota, spread over 1,045.176 square miles. Averaged across its land area, Clay County runs about 64 people per square mile. Rank 251 by population within its EPA zone puts Clay County at the 77th percentile among zone peers. EPA's geology-based Region 5 groups Clay County with 523 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Clay County's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. Some Clay 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.

Next steps for a home in Clay County

Nothing about Clay 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 Minnesota's state radon program

Clay County's test kit answers today; a Airthings radon monitor keeps answering for Clay 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 Clay County carries, the zone explainer covers what it does and doesn't tell you about any one house.