Smith County, TX Radon Zone Data

Smith County, TX: EPA's radon zone, explained

Smith County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. Rank it against the rest of the country and Smith County lands in the 30th percentile for radon potential.

Smith County by the numbers

Smith County, Texas is home to about 249,091 people across 921.495 square miles. That works out to roughly 270 people per square mile. By population, Smith County is the 106th largest of every county sharing its EPA zone — the 90th percentile by population within that zone. Geologically, Smith 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

At Zone 3, Smith County's predicted county average is under the national indoor average (~1.3 pCi/L) and well below EPA's 4 pCi/L action level — outdoor air nationally runs about 0.4 pCi/L for comparison. A Zone 3 rating means Smith County's county-wide average is predicted low, but EPA is explicit that a meaningful share of homes in low-potential zones still test above the action level — a low zone is not a reason to skip testing.

If Smith County tests above the action level

For a Smith 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 Texas'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. RADONZONE-10OFF at checkout knocks 10% off.

Where Smith County's figures come from

Smith County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. Whatever zone Smith County carries, the zone explainer covers what it does and doesn't tell you about any one house.