Douglas County, WA: EPA's radon zone, explained

EPA's own radon map rates Douglas County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. Nationally that's the 54th percentile for radon potential — Douglas County outranks 54% of every county EPA has rated.

Where Douglas County sits nationally

Douglas County, Washington is home to about 45,795 people across 1,819.244 square miles. That works out to roughly 25 people per square mile. By population, Douglas County is the 360th largest of every county sharing its EPA zone — the 65th percentile by population within that zone. Geologically, Douglas County is grouped into EPA Region 10 alongside 141 other counties that share its rock and soil setting.

What this actually means for a house in Douglas County

EPA's Zone 2 rating for Douglas County sits below its own 4 pCi/L action level but above the national indoor average of about 1.3 pCi/L. Nothing about a Zone 2 label lowers the case for testing in Douglas County — EPA recommends it in every zone, moderate included.

Testing and mitigation in Douglas County

For a Douglas County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.

Find Washington's state radon program

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

Where Douglas County's figures come from

Douglas County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.