Smith County, TN radon potential

EPA's own radon map rates Smith County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Rank it against the rest of the country and Smith County lands in the 82nd percentile for radon potential.

How Smith County compares

Smith County, Tennessee is home to about 20,783 people across 314.278 square miles. Averaged across its land area, Smith County runs about 66 people per square mile. Within its own EPA zone, Smith County is bigger by population than 47% of the counties that share it. Geologically, Smith County is grouped into EPA Region 4 alongside 735 other counties that share its rock and soil setting.

What this actually means for a house in Smith County

Smith 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. 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 Smith County will test well under the action level, and EPA's guidance is to test regardless of zone.

Testing and mitigation in Smith 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 Smith County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Smith 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 Smith County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Smith County's numbers. Whatever zone Smith County carries, the zone explainer covers what it does and doesn't tell you about any one house.