You can't avoid it completely, and it can cause cancer. However, you can take steps to reduce your exposure to it.
"It" is radon, and it is common in central Kentucky.
"The radon that's in Marion County is here as a result of the geology, specifically the black shale," said Keith Brock, the Marion County Solid Waste and Environmental Coordinator.
Radon is produced by the natural decay of uranium, which is found in nearly all soils, according to the Environmental Protection Agency.