What EPA's radon map says about Kitsap County

EPA places Kitsap 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. Kitsap County sits at the 30th percentile nationally for radon potential — above 30 of every 100 rated counties.

Kitsap County by the numbers

About 281,420 people live in Kitsap County, Washington, spread over 395.087 square miles. Averaged across its land area, Kitsap County runs about 712 people per square mile. Among counties sharing Kitsap County's EPA zone, it outranks 91% of them by population. Kitsap 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

Kitsap 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. Low doesn't mean zero: EPA's own data shows homes in Zone 3 counties like Kitsap County testing above the action level often enough that skipping a test isn't the safe assumption.

If Kitsap County tests above the action level

Mitigation cost doesn't depend on Kitsap 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 Washington's state radon program

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

The methodology guide shows exactly which EPA and Census sources feed Kitsap County's numbers. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.