Is Union County, IN a radon risk area?

Union County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. That puts Union County in the 73rd percentile nationally for radon potential — higher than 73% of the counties EPA has rated.

Union County by the numbers

About 6,884 people live in Union County, Indiana, spread over 161.191 square miles. Population density there runs about 43 people per square mile. Rank 851 by population within its EPA zone puts Union County at the 20th percentile among zone peers. Geologically, Union 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

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Union County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. EPA's guidance doesn't change because of a Zone 1 label: test the house. What changes is the reason to not put it off in Union County specifically.

Next steps for a home in Union County

Nothing about Union 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 Indiana's state radon program

Union County's test kit answers today; a Airthings radon monitor keeps answering for Union 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. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.