Is Glacier County, MT a radon risk area?

Glacier 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 Glacier County lands in the 78th percentile for radon potential.

Glacier County by the numbers

About 13,503 people live in Glacier County, Montana, spread over 2,995.151 square miles. That works out to roughly 5 people per square mile. Rank 696 by population within its EPA zone puts Glacier County at the 35th percentile among zone peers. EPA's geology-based Region 8 groups Glacier County with 290 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Glacier County

Glacier 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. That doesn't mean every Glacier County house tests high — a zone is a county-wide prediction, never a single-home reading — but it's a reason to test sooner rather than let it wait.

Testing and mitigation in Glacier County

Nothing about Glacier 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

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