Is Beaverhead County, MT a radon risk area?

Beaverhead County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Nationally, Beaverhead County ranks higher in radon potential than 76% of rated counties (the 76th percentile).

Beaverhead County by the numbers

About 10,006 people live in Beaverhead County, Montana, spread over 5,542.687 square miles. Population density there runs about 2 people per square mile. Rank 763 by population within its EPA zone puts Beaverhead County at the 28th percentile among zone peers. EPA's geology-based Region 8 groups Beaverhead County with 290 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Beaverhead County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. A Zone 1 rating means testing is worth doing sooner rather than later, but it is still county-wide average, not a reading for any single house — some homes in Beaverhead County will test well under the action level, and EPA's guidance is to test regardless of zone.

Next steps for a home in Beaverhead County

Nothing about Beaverhead 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

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

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.