Map from the paper showing the spatial distributions of predicted radon concentrations at screening floor in winter. L. Li, B.A. Coull, C.L. Zilli Vieira, P. Koutrakis, High-resolution national ...

The bad: A map developed by the Department of Health shows how 40 percent of the state’s homes have dangerous levels of radon. In McLeod County, the rate is even higher, between 54 and 67 ...