What EPA's radon map says about Douglas County

Douglas County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. Rank it against the rest of the country and Douglas County lands in the 26th percentile for radon potential.

How Douglas County compares

About 112,255 people live in Douglas County, Oregon, spread over 5,035.755 square miles. That works out to roughly 22 people per square mile. Among counties sharing Douglas County's EPA zone, it outranks 80% of them by population. Douglas County falls in EPA Radon Region 10, one of 142 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

At Zone 3, Douglas County's predicted county average is under the national indoor average (~1.3 pCi/L) and well below EPA's 4 pCi/L action level — outdoor air nationally runs about 0.4 pCi/L for comparison. A Zone 3 rating means Douglas County's county-wide average is predicted low, but EPA is explicit that a meaningful share of homes in low-potential zones still test above the action level — a low zone is not a reason to skip testing.

If Douglas County tests above the action level

Mitigation cost doesn't depend on Douglas County's zone — it depends on the house's foundation. A typical system runs $800–$2,500 (about $1,200 typical), and testing first is what tells you whether that's needed at all.

Find Oregon's state radon program

Douglas County's test kit answers today; a Airthings radon monitor keeps answering for Douglas County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. Use code RADONZONE-10OFF at checkout for 10% off.

More on how this number was built

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.