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

EPA places Shelby 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. Nationally, Shelby County ranks higher in radon potential than 32% of rated counties (the 32nd percentile).

Where Shelby County sits nationally

Shelby County, Tennessee is home to about 910,530 people across 752.775 square miles. Averaged across its land area, Shelby County runs about 1,210 people per square mile. By population, Shelby County is the 32nd largest of every county sharing its EPA zone — the 97th percentile by population within that zone. Geologically, Shelby County is grouped into EPA Region 4 alongside 735 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

Well clear of both the 1.3 pCi/L national indoor average and EPA's 4 pCi/L action level, Shelby County's Zone 3 prediction is the low end of the scale. Low doesn't mean zero: EPA's own data shows homes in Zone 3 counties like Shelby County testing above the action level often enough that skipping a test isn't the safe assumption.

Next steps for a home in Shelby County

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

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.