Garfield County, MT radon potential

EPA's own radon map rates Garfield County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Nationally that's the 66th percentile for radon potential — Garfield County outranks 66% of every county EPA has rated.

Garfield County by the numbers

Garfield County, Montana is home to about 1,181 people across 4,676.56 square miles. Averaged across its land area, Garfield County runs about 0 people per square mile. Within its own EPA zone, Garfield County is bigger by population than 1% of the counties that share it. EPA's geology-based Region 8 groups Garfield County with 290 other counties nationally sharing its underlying rock and soil profile.

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 — Garfield County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. That doesn't mean every Garfield 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.

Next steps for a home in Garfield County

A short-term test kit is the standard first step and typically costs far less than mitigation itself. If a test comes back at or above 4 pCi/L, a radon mitigation system for a typical home runs roughly $800–$2,500 (around $1,200 for a common single-family install), driven mainly by foundation type, not by county.

Find Montana's state radon program

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

Where Garfield County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Garfield County's numbers. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.