What EPA's radon map says about Union County

EPA places Union 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. Rank it against the rest of the country and Union County lands in the 49th percentile for radon potential.

Where Union County sits nationally

About 26,058 people live in Union County, Oregon, spread over 2,036.941 square miles. That works out to roughly 13 people per square mile. Among counties sharing Union County's EPA zone, it outranks 48% of them by population. Union County falls in EPA Radon Region 10, one of 142 counties nationally EPA assigns to that same geologic province.

What this actually means for a house in Union County

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

If Union County tests above the action level

Mitigation cost doesn't depend on Union 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

Union County's test kit answers today; a Airthings radon monitor keeps answering for Union 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

Union County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. Whatever zone Union County carries, the zone explainer covers what it does and doesn't tell you about any one house.