Radon is a radioactive gas that comes from the decay of radium in the soil.
Radium is a decay product of uranium.
Radon is a colorless, odorless, invisible gas that occurs naturally. Chronic exposure to elevated radon levels has been linked to an increased incidence of lung cancer in humans. For most people, radon is their largest source of exposure to nuclear radiation. Many homes, particularly homes in the upper Midwest, contain radon concentrations that are high enough to give their occupants lifetime exposures of the same size as those received by underground miners who showed the increased risk of lung cancer mortality. When radon and its decay products are inhaled into your lungs they emit energetic particles called alpha particles.