Polk County, OR: EPA's radon zone, explained

EPA's own radon map rates Polk County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Nationally that's the 26th percentile for radon potential — Polk County outranks 26% of every county EPA has rated.

Where Polk County sits nationally

Polk County, Oregon is home to about 90,549 people across 740.924 square miles. Averaged across its land area, Polk County runs about 122 people per square mile. By population, Polk County is the 229th largest of every county sharing its EPA zone — the 78th percentile by population within that zone. Geologically, Polk County is grouped into EPA Region 10 alongside 141 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

Polk County's predicted average sits below the national indoor average of about 1.3 pCi/L, well under EPA's 4 pCi/L action level. A Zone 3 rating means Polk 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.

Testing and mitigation in Polk County

For a Polk 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 Oregon's state radon program

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

Where Polk County's figures come from

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