Washington County, VA radon potential

EPA's own radon map rates Washington County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Nationally that's the 91st percentile for radon potential — Washington County outranks 91% of every county EPA has rated.

How Washington County compares

Washington County, Virginia is home to about 54,098 people across 561.193 square miles. Averaged across its land area, Washington County runs about 96 people per square mile. Within its own EPA zone, Washington County is bigger by population than 72% of the counties that share it. Geologically, Washington 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

Where the national indoor average runs about 1.3 pCi/L, Washington County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. Some Washington 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.

If Washington 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 Virginia's state radon program

For Washington County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Washington 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 Washington 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. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.