Is Clallam County, WA a radon risk area?

Clallam 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 Clallam County lands in the 25th percentile for radon potential.

Clallam County by the numbers

About 77,958 people live in Clallam County, Washington, spread over 1,738.776 square miles. Population density there runs about 45 people per square mile. Rank 255 by population within its EPA zone puts Clallam County at the 75th percentile among zone peers. EPA's geology-based Region 10 groups Clallam County with 141 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

At Zone 3, Clallam 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. Don't read Zone 3 as a pass for Clallam County — EPA's guidance to test every home makes no exception for counties predicted low.

Next steps for a home in Clallam County

Nothing about Clallam County's EPA zone changes the mitigation number: $800–$2,500 nationally (around $1,200 typical), set by the house's foundation rather than the county it sits in — and only relevant once a test actually clears 4 pCi/L.

Find Washington's state radon program

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

Clallam County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.