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

EPA's own radon map rates Madison County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Madison County sits at the 10th percentile nationally for radon potential — above 10 of every 100 rated counties.

Madison County by the numbers

Madison County, Texas is home to about 13,877 people across 466.116 square miles. That works out to roughly 30 people per square mile. By population, Madison County is the 733rd largest of every county sharing its EPA zone — the 29th percentile by population within that zone. EPA's geology-based Region 6 groups Madison County with 502 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, Madison County's Zone 3 prediction is the low end of the scale. A Zone 3 label describes Madison County's average, not any one basement or slab in it — testing is still the only way an individual homeowner actually finds out.

If Madison County tests above the action level

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

Where Madison County's figures come from

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