Marion County, WV radon potential

EPA places Marion County in Zone 2 - Moderate Potential — a predicted county-wide average indoor radon level between 2 and 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Nationally that's the 56th percentile for radon potential — Marion County outranks 56% of every county EPA has rated.

Where Marion County sits nationally

Marion County, West Virginia is home to about 55,649 people across 308.785 square miles. Averaged across its land area, Marion County runs about 180 people per square mile. Within its own EPA zone, Marion County is bigger by population than 69% of the counties that share it. Geologically, Marion County is grouped into EPA Region 3 alongside 244 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

EPA's Zone 2 rating for Marion County sits below its own 4 pCi/L action level but above the national indoor average of about 1.3 pCi/L. A Zone 2 rating is a moderate county-wide average, not a guarantee about any one house in Marion County — testing is the only way to know an individual home's actual level.

Next steps for a home in Marion 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 West Virginia's state radon program

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

Where Marion 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. Whatever zone Marion County carries, the zone explainer covers what it does and doesn't tell you about any one house.