What EPA's radon map says about Otter Tail County

EPA's own radon map rates Otter Tail County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Rank it against the rest of the country and Otter Tail County lands in the 91st percentile for radon potential.

How Otter Tail County compares

About 60,884 people live in Otter Tail County, Minnesota, spread over 1,971.636 square miles. Averaged across its land area, Otter Tail County runs about 31 people per square mile. Among counties sharing Otter Tail County's EPA zone, it outranks 75% of them by population. Geologically, Otter Tail 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

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Otter Tail County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. Being in Zone 1 raises the odds Otter Tail 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.

If Otter Tail County tests above the action level

Mitigation cost doesn't depend on Otter Tail County's zone — it depends on the house's foundation. A typical system runs $800–$2,500 (about $1,200 typical), and testing first is what tells you whether that's needed at all.

Find Minnesota's state radon program

Otter Tail County's test kit answers today; a Airthings radon monitor keeps answering for Otter Tail County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

More on how this number was built

The methodology guide shows exactly which EPA and Census sources feed Otter Tail County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.