Where Radon Comes From

Radon gas comes from the natural breaking down of uranium in almost all soils.  Uranium breaks down into radium, which then further disintegrates and turns into radon - a radioactive gas.  This gas leaves the soil and becomes part of the air we breathe.  There is no known, safe level of radon gas exposure.

 

image from http://www.health.state.mn.us/divs/eh/indoorair/radon/radonconbrochure.pdf