Is Toole County, MT a radon risk area?

Toole County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Rank it against the rest of the country and Toole County lands in the 71st percentile for radon potential.

Where Toole County sits nationally

About 5,153 people live in Toole County, Montana, spread over 1,914.864 square miles. That works out to roughly 3 people per square mile. Rank 920 by population within its EPA zone puts Toole County at the 14th percentile among zone peers. EPA's geology-based Region 8 groups Toole County with 290 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Toole County

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

If Toole County tests above the action level

Nothing about Toole 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 Montana's state radon program

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

Toole County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. Whatever zone Toole County carries, the zone explainer covers what it does and doesn't tell you about any one house.