Carroll County, TN: EPA's radon zone, explained

EPA places Carroll 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. That puts Carroll County in the 17th percentile nationally for radon potential — higher than 17% of the counties EPA has rated.

Where Carroll County sits nationally

Carroll County, Tennessee is home to about 29,107 people across 597.658 square miles. Averaged across its land area, Carroll County runs about 49 people per square mile. By population, Carroll County is the 491st largest of every county sharing its EPA zone — the 52nd percentile by population within that zone. EPA's geology-based Region 4 groups Carroll County with 735 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

Well clear of both the 1.3 pCi/L national indoor average and EPA's 4 pCi/L action level, Carroll County's Zone 3 prediction is the low end of the scale. Even at Zone 3, Carroll County homes are not guaranteed a low reading — zone is a county-wide average, and EPA recommends testing every home regardless of zone.

Next steps for a home in Carroll County

For a Carroll County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.

Find Tennessee's state radon program

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

Where Carroll 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. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.