Is Ottawa County, KS a radon risk area?

EPA's own radon map rates Ottawa County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Rank it against the rest of the country and Ottawa County lands in the 72nd percentile for radon potential.

Ottawa County by the numbers

About 5,853 people live in Ottawa County, Kansas, spread over 720.73 square miles. Population density there runs about 8 people per square mile. Rank 887 by population within its EPA zone puts Ottawa County at the 17th percentile among zone peers. Ottawa County falls in EPA Radon Region 7, one of 412 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Ottawa County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. A Zone 1 rating means testing is worth doing sooner rather than later, but it is still county-wide average, not a reading for any single house — some homes in Ottawa County will test well under the action level, and EPA's guidance is to test regardless of zone.

If Ottawa County tests above the action level

Nothing about Ottawa 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 Kansas's state radon program

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

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.