Is Marshall County, KY a radon risk area?

Marshall County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. Marshall County sits at the 18th percentile nationally for radon potential — above 18 of every 100 rated counties.

Where Marshall County sits nationally

About 31,734 people live in Marshall County, Kentucky, spread over 302.126 square miles. Averaged across its land area, Marshall County runs about 105 people per square mile. Rank 466 by population within its EPA zone puts Marshall County at the 55th percentile among zone peers. Marshall County falls in EPA Radon Region 4, one of 736 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

A Zone 3 county like Marshall County is predicted closer to the 0.4 pCi/L typical outdoors than to EPA's 4 pCi/L action level. A Zone 3 label describes Marshall County's average, not any one basement or slab in it — testing is still the only way an individual homeowner actually finds out.

If Marshall County tests above the action level

Nothing about Marshall 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 Kentucky's state radon program

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

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.