Sheridan County, MT radon potential

Sheridan County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Nationally that's the 69th percentile for radon potential — Sheridan County outranks 69% of every county EPA has rated.

How Sheridan County compares

Sheridan County, Montana is home to about 3,448 people across 1,676.941 square miles. Population density there runs about 2 people per square mile. Within its own EPA zone, Sheridan County is bigger by population than 9% of the counties that share it. Sheridan 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 Sheridan County

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Sheridan County's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. That doesn't mean every Sheridan 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.

If Sheridan County tests above the action level

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

Where Sheridan County's figures come from

Sheridan 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.