Radon Levels in Chattanooga: What's Normal, What's High, and What to Do

Every radon conversation eventually comes down to one number, so here it is: 4.0 pCi/L. That's the EPA action level — at or above it, fix the house. Between 2.0 and 4.0, the EPA says consider fixing it. Below 2.0 is about as good as houses get. There is no truly "safe" level, because risk scales smoothly with exposure, but those are the working thresholds every inspector, agent, and mitigation contractor in Tennessee uses.

What do Chattanooga homes actually test at?

East Tennessee's ridge-and-valley geology — fractured limestone and shale shedding off Signal Mountain, Lookout Mountain, and Missionary Ridge — produces elevated radon potential across Hamilton County, which the EPA classifies in its higher-risk zones. In practice that means a meaningful share of local homes test above 4.0, some dramatically so, while the house next door tests at 1.0. Radon rides up through rock fractures and soil gas, so results are hyper-local: your neighbor's number tells you nothing about yours.

Why the same house tests differently in January and July

Radon levels swing with the seasons. Closed-up winter houses concentrate radon; the stack effect (warm air rising and pulling soil gas up through the slab) is strongest in cold months. A house that tests 3.1 in July can test 5.8 in January. That's why a marginal summer result deserves a winter re-test, and why real-estate tests follow closed-house protocol — windows shut, systems running normally — so the number reflects how the family will actually live.

Reading your test report

A 48-hour continuous-monitor test gives you an overall average plus hourly readings. The average is what counts against the 4.0 threshold. Big hourly swings are normal; a tamper flag or an unexplained flat line is not, and a good report explains both. If your average lands between 2.0 and 4.0, you're in judgment territory: a basement bedroom or a kid's playroom down there argues for fixing it; an unused crawlspace argues for re-testing in winter first.

If the number is high, the fix is boring — in a good way

Radon is the rare environmental problem with a definitive, one-day, guaranteed fix. A sub-slab depressurization system — one sealed suction point, a pipe run, and a quiet inline fan — typically cuts levels 80–99% and costs $900–$2,500 in the Chattanooga area depending on foundation type. Every system we install is guaranteed in writing to bring the home under 4.0, verified by a follow-up test. Crawlspace homes use a sealed membrane version that works just as well.

Know your number

A certified 48-hour test is typically $150 or less, credited toward a system if you need one — and if you're mid-transaction, our real-estate testing is built for inspection windows. Call (423) 529-4385 and we'll get a monitor placed this week.