Ottawa County, OH radon potential

EPA's own radon map rates Ottawa County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. Ottawa County sits at the 53rd percentile nationally for radon potential — above 53 of every 100 rated counties.

Where Ottawa County sits nationally

Ottawa County, Ohio is home to about 39,692 people across 254.685 square miles. That works out to roughly 156 people per square mile. Within its own EPA zone, Ottawa County is bigger by population than 61% of the counties that share it. Geologically, Ottawa County is grouped into EPA Region 5 alongside 523 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

EPA's Zone 2 rating for Ottawa County sits below its own 4 pCi/L action level but above the national indoor average of about 1.3 pCi/L. A Zone 2 rating is a moderate county-wide average, not a guarantee about any one house in Ottawa County — testing is the only way to know an individual home's actual level.

If Ottawa County tests above the action level

A short-term test kit is the standard first step and typically costs far less than mitigation itself. If a test comes back at or above 4 pCi/L, a radon mitigation system for a typical home runs roughly $800–$2,500 (around $1,200 for a common single-family install), driven mainly by foundation type, not by county.

Find Ohio's state radon program

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

Where Ottawa County's figures come from

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.