Fergus County, MT radon potential

EPA's own radon map rates Fergus County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Nationally that's the 77th percentile for radon potential — Fergus County outranks 77% of every county EPA has rated.

Fergus County by the numbers

Fergus County, Montana is home to about 11,862 people across 4,339.329 square miles. That works out to roughly 3 people per square mile. Within its own EPA zone, Fergus County is bigger by population than 32% of the counties that share it. Fergus County falls in EPA Radon Region 8, one of 291 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Fergus County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. Some Fergus County homes will test comfortably under the action level despite the county's Zone 1 rating — the only way to know which kind of home you have is an actual test.

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

Where Fergus County's figures come from

Fergus County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.