Is Bullitt County, KY a radon risk area?

EPA places Bullitt County in Zone 1 - Highest Potential — a predicted county-wide average indoor radon level above 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Rank it against the rest of the country and Bullitt County lands in the 93rd percentile for radon potential.

Where Bullitt County sits nationally

About 85,802 people live in Bullitt County, Kentucky, spread over 297.088 square miles. That works out to roughly 289 people per square mile. Rank 216 by population within its EPA zone puts Bullitt County at the 80th percentile among zone peers. Geologically, Bullitt County is grouped into EPA Region 4 alongside 735 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Bullitt 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 Bullitt County will test well under the action level, and EPA's guidance is to test regardless of zone.

Testing and mitigation in Bullitt County

Nothing about Bullitt 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

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

Bullitt County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.