What EPA's radon map says about Josephine County

EPA places Josephine County in Zone 3 - Low Potential — a predicted county-wide average indoor radon level below 2 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Nationally that's the 26th percentile for radon potential — Josephine County outranks 26% of every county EPA has rated.

Where Josephine County sits nationally

About 88,276 people live in Josephine County, Oregon, spread over 1,638.649 square miles. That works out to roughly 54 people per square mile. Among counties sharing Josephine County's EPA zone, it outranks 78% of them by population. Josephine County falls in EPA Radon Region 10, one of 142 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Josephine County's Zone 3 prediction undercuts the roughly 1.3 pCi/L most US homes average, nowhere near EPA's 4 pCi/L threshold for recommending mitigation. Don't read Zone 3 as a pass for Josephine County — EPA's guidance to test every home makes no exception for counties predicted low.

Next steps for a home in Josephine County

Mitigation cost doesn't depend on Josephine 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

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

The methodology guide shows exactly which EPA and Census sources feed Josephine County's numbers. Whatever zone Josephine County carries, the zone explainer covers what it does and doesn't tell you about any one house.