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

EPA places Collin 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 Collin County in the 32nd percentile nationally for radon potential — higher than 32% of the counties EPA has rated.

How Collin County compares

Collin County, Texas is home to about 1,254,658 people across 841.513 square miles. That works out to roughly 1,491 people per square mile. By population, Collin County is the 22nd largest of every county sharing its EPA zone — the 98th percentile by population within that zone. Geologically, Collin County is grouped into EPA Region 6 alongside 502 other counties that share its rock and soil setting.

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, Collin County's Zone 3 prediction is the low end of the scale. A Zone 3 label describes Collin County's average, not any one basement or slab in it — testing is still the only way an individual homeowner actually finds out.

Testing and mitigation in Collin County

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

Where Collin County's figures come from

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