Knox County is EPA Zone 1 for radon: what does that mean for homeowners?

Zone map vs. your address

The EPA zone map is a county-scale planning tool. It averages predicted indoor potential across broad geology. It cannot see your sealed crawl, your cracked basement slab, or your neighbor's clean short-term result. Two Fountain City basements a block apart can disagree. A new Hardin Valley slab can outrank an older Bearden ranch. Test the house you care about.

What Zone 1 should change in your behavior:

• Don't skip radon when buying in Knox County
• Don't assume "we never smelled anything" equals safe
• Do retest after major foundation or HVAC work
• Do take results at or above 4 pCi/L seriously, and weigh action in the 2–4 band

Why East Tennessee shows up elevated

Radon forms from the natural decay of uranium in rock and soil. East Tennessee geology includes uranium-bearing formations that feed soil gas into homes through foundations. The Tennessee radon program has long noted that elevated indoor radon is common in East TN. Free DIY kits are available through 1-800-232-1139 if you want a first look; professional tests (often about $150–$250 locally) fit real estate and mitigation decisions better.

What homeowners should do next

1. If you've never tested: schedule a short-term or continuous test. Start with radon testing in Knoxville.
2. If you're buying: fold testing into the contingency. See home-buyer testing.
3. If results are high: plan ASD mitigation sized to basement, crawl, or slab. Market installs often run about $800–$2,500, with Knox County planning bands frequently cited around $1,300–$2,500. Details: mitigation.
4. After a system: retest and keep the paperwork.

Zone 1 is a heads-up, not a scarlet letter on your deed. Plenty of Knox County homes test low. Plenty need a fan. The zone only tells you which question to ask; the monitor answers it.

Zone 1, Zone 2, Zone 3 (quick orientation)

EPA maps counties into three predicted potential zones. Zone 1 is the highest predicted average (above 4 pCi/L). Zone 2 is moderate. Zone 3 is predicted lower. Knox County's Zone 1 label puts it with other higher-potential counties nationwide. Crossing into a neighboring county can change the zone label on a map; it does not change the rule that you still test any individual house you're buying or living in.

Predictions use geology, soil, and aerial radioactivity data, among other inputs. They are not a substitute for a charcoal kit or continuous monitor in your basement.

Myths we hear in Knoxville

• "New houses don't get radon." False. Tight envelopes can hold gas that enters through slabs and penetrations.
• "If the neighbor tested low, I'm fine." False. Soil permeability and foundation detailing vary lot to lot.
• "Opening windows fixes it permanently." Ventilation can lower a short-term reading; it isn't a mitigation system and fails as a winter strategy.
• "Zone 1 means I must mitigate before I even test." No. Test first. Mitigate when the number calls for it.

Talk to a local shop

Call (865) 420-6136 or email info@radonknoxville.com with your ZIP and foundation type. We'll schedule testing across Knoxville and Knox County, including Farragut, Hardin Valley, Fountain City, Bearden, and South Knox. County overview: service area hub.