Obion County, TN: EPA's radon zone, explained

Obion County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. Nationally, Obion County ranks higher in radon potential than 18% of rated counties (the 18th percentile).

How Obion County compares

Obion County, Tennessee is home to about 30,261 people across 544.851 square miles. That works out to roughly 56 people per square mile. By population, Obion County is the 479th largest of every county sharing its EPA zone — the 54th percentile by population within that zone. EPA's geology-based Region 4 groups Obion County with 735 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

Obion County's Zone 3 prediction undercuts the roughly 1.3 pCi/L most US homes average, nowhere near EPA's 4 pCi/L threshold for recommending mitigation. A Zone 3 rating means Obion 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 Obion County tests above the action level

For a Obion 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 Tennessee's state radon program

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

Obion County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.