Radon In Basement Umbra

Why Radon in Basement Levels Are Often Highest and What to Do About It

After years of testing homes across the St. Louis area, I have seen the same pattern again and again. The highest radon readings almost always come from the lowest level of the house. Whether you call it a basement, a crawl space, or a slab-on-grade utility room, the physics is simple. Radon enters from the soil beneath the foundation, and that soil contact is greatest at the lowest floor. The result is that radon in basement spaces tends to accumulate more than anywhere els