Union County, TN radon potential

EPA places Union 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. Nationally, Union County ranks higher in radon potential than 82% of rated counties (the 82nd percentile).

How Union County compares

Union County, Tennessee is home to about 21,064 people across 223.583 square miles. Averaged across its land area, Union County runs about 94 people per square mile. Within its own EPA zone, Union County is bigger by population than 48% of the counties that share it. EPA's geology-based Region 4 groups Union County with 735 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

Union County's predicted average sits above EPA's own action level of 4 pCi/L — the concentration at which EPA recommends fixing a home — versus a national average around 1.3 pCi/L indoors and 0.4 pCi/L outdoors. That doesn't mean every Union County house tests high — a zone is a county-wide prediction, never a single-home reading — but it's a reason to test sooner rather than let it wait.

Next steps for a home in Union County

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 Tennessee's state radon program

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

Where Union 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.