Lyon County, MN: EPA's radon zone, explained

Lyon 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 Lyon County in the 84th percentile nationally for radon potential — higher than 84% of the counties EPA has rated.

Lyon County by the numbers

Lyon County, Minnesota is home to about 25,577 people across 714.411 square miles. Averaged across its land area, Lyon County runs about 36 people per square mile. By population, Lyon County is the 512th largest of every county sharing its EPA zone — the 52nd percentile by population within that zone. Geologically, Lyon County is grouped into EPA Region 5 alongside 523 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

Lyon 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. Some Lyon 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.

Testing and mitigation in Lyon County

For a Lyon 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 Minnesota's state radon program

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

Where Lyon 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. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.