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

Trinity County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. That puts Trinity County in the 10th percentile nationally for radon potential — higher than 10% of the counties EPA has rated.

How Trinity County compares

Trinity County, Texas is home to about 14,489 people across 693.857 square miles. That works out to roughly 21 people per square mile. By population, Trinity County is the 720th largest of every county sharing its EPA zone — the 30th percentile by population within that zone. EPA's geology-based Region 6 groups Trinity County with 502 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Trinity County

A Zone 3 county like Trinity County is predicted closer to the 0.4 pCi/L typical outdoors than to EPA's 4 pCi/L action level. A Zone 3 rating means Trinity 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 Trinity County tests above the action level

For a Trinity 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 Trinity County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Trinity 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 Trinity County's figures come from

Trinity County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.