Radon is the one home hazard you cannot see, smell, or taste, and Kansas City has more of it than most of the country. This reference lays out the facts: why the metro is a high-risk zone, what the numbers mean, and how testing and mitigation work. It is meant to be a plain, citable starting point for KC homeowners and home buyers.
The EPA divides the country into three radon zones. Zone 1 is the highest, meaning the predicted average indoor level is at or above the action level. The entire Kansas City metro, on both the Kansas and Missouri sides, sits in Zone 1. This is a function of our geology: the soils and bedrock here release more radon gas than average, and it seeps up into homes through the foundation.
| Figure | Value | What it means |
|---|---|---|
| EPA action level | 4.0 pCi/L | At or above this, the EPA recommends mitigation |
| KC-area average | ~4.6 pCi/L | The local average is already above the action level |
| Homes elevated | ~1 in 3–4 | Roughly a quarter to a third of KC homes test high |
| WHO reference | 2.7 pCi/L | The World Health Organization suggests a lower threshold |
Radon is measured in picocuries per liter (pCi/L). It is the second leading cause of lung cancer after smoking, and the leading cause among people who have never smoked, which is why testing is recommended for every home regardless of age or type.
Slab homes, homes with basements, and crawl-space homes can all test high, so foundation type does not exempt you. Learn more on radon testing.
The standard, proven fix is active sub-slab depressurization: a pipe is sealed into the slab and a continuous fan draws radon-laden soil gas from beneath the foundation and vents it safely above the roofline before it enters your air. Most systems install in a few hours, and a post-mitigation test confirms the level is back below 4.0 pCi/L. Details on mitigation systems, and if a test came back high during a sale, real estate radon is handled on the contract's timeline.
Bottom line: because the entire KC metro is Zone 1 and the local average already exceeds the action level, every home here is worth testing. If a test reads 4.0 pCi/L or higher, a mitigation system reliably brings it down, usually in a single afternoon.
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