Mineral County, MT: EPA's radon zone, explained

EPA's own radon map rates Mineral County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Nationally that's the 71st percentile for radon potential — Mineral County outranks 71% of every county EPA has rated.

How Mineral County compares

Mineral County, Montana is home to about 5,195 people across 1,219.619 square miles. That works out to roughly 4 people per square mile. By population, Mineral County is the 919th largest of every county sharing its EPA zone — the 14th percentile by population within that zone. Mineral County falls in EPA Radon Region 8, one of 291 counties nationally EPA assigns to that same geologic province.

What this actually means for a house in Mineral County

Where the national indoor average runs about 1.3 pCi/L, Mineral County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. 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 Mineral County will test well under the action level, and EPA's guidance is to test regardless of zone.

Next steps for a home in Mineral County

For a Mineral 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 Montana's state radon program

For Mineral County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Mineral County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

Where Mineral 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. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.