Date Published: 10/19/2007 [Source]
Professor Williams said that we absorb radon from groundwater, construction materials and directly from the soil beneath our homes.
"In the Twin Cities it's the shales that may contain minerals that contribute to radon," he said.
The professor said Taylors Falls to the north sits on a bed of basalt which probably contributes more radon. Living on granite such as in North Central Wisconsin, is probably a stronger source of radon gas.