What EPA's radon map says about Umatilla County

EPA's own radon map rates Umatilla County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. Umatilla County sits at the 58th percentile nationally for radon potential — above 58 of every 100 rated counties.

How Umatilla County compares

About 80,491 people live in Umatilla County, Oregon, spread over 3,215.45 square miles. Population density there runs about 25 people per square mile. Among counties sharing Umatilla County's EPA zone, it outranks 77% of them by population. Umatilla County falls in EPA Radon Region 10, one of 142 counties nationally EPA assigns to that same geologic province.

Why the zone isn't the answer by itself

Neither at the 4 pCi/L action level nor down at the roughly 1.3 pCi/L national indoor norm, Umatilla County's Zone 2 prediction lands in the gap between the two. A county-wide moderate average, like Umatilla County's, can still hide a specific house well above or below it — testing is what actually answers the question.

Next steps for a home in Umatilla County

Mitigation cost doesn't depend on Umatilla 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

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