Is Union County, AR a radon risk area?

EPA places Union County in Zone 3 - Low Potential — a predicted county-wide average indoor radon level below 2 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Union County sits at the 19th percentile nationally for radon potential — above 19 of every 100 rated counties.

Where Union County sits nationally

About 37,008 people live in Union County, Arkansas, spread over 1,039.067 square miles. Population density there runs about 36 people per square mile. Rank 425 by population within its EPA zone puts Union County at the 59th percentile among zone peers. Geologically, Union County is grouped into EPA Region 6 alongside 502 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

Union County's Zone 3 prediction undercuts the roughly 1.3 pCi/L most US homes average, nowhere near EPA's 4 pCi/L threshold for recommending mitigation. Don't read Zone 3 as a pass for Union County — EPA's guidance to test every home makes no exception for counties predicted low.

If Union County tests above the action level

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 Arkansas'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. Code RADONZONE-10OFF takes 10% off at checkout.

More on how this number was built

The methodology guide shows exactly which EPA and Census sources feed Union County's numbers. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.