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

Olmsted 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 96th percentile for radon potential — Olmsted County outranks 96% of every county EPA has rated.

Where Olmsted County sits nationally

Olmsted County, Minnesota is home to about 166,424 people across 653.509 square miles. That works out to roughly 255 people per square mile. By population, Olmsted County is the 119th largest of every county sharing its EPA zone — the 89th percentile by population within that zone. Geologically, Olmsted County is grouped into EPA Region 5 alongside 523 other counties that share its rock and soil setting.

Zone vs. an actual test

Olmsted County's predicted average sits above EPA's own action level of 4 pCi/L — the concentration at which EPA recommends fixing a home — versus a national average around 1.3 pCi/L indoors and 0.4 pCi/L outdoors. Being in Zone 1 raises the odds Olmsted 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 Olmsted County

For a Olmsted 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 Olmsted County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Olmsted 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 Olmsted 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.