Radon gas is continually released by uranium-bearing rocks and soil as the uranium undergoes natural radioactive decay. The gas moves through the soil freely because it is chemically non-reactive and does not combine with other materials. When the radon gas reaches the outdoor air, it is quickly diluted to low concentrations. However, radon can accumulate under the slabs and foundations of buildings and can easily enter through cracks and openings, sometimes causing high indoor concentrations.
Radon decays into other radioactive elements(which are solid particles)--often referred to as radon decay products or radon progeny. When radon progeny are inhaled, they can lodge in the lungs and deliver radiation doses to sensitive lung tissue as the progeny continue to decay.
URANIUM 238 DECAY SERIES
URANIUM-238 THORIUM-234 PROTACTIUM-234 URANIUM-234 THORIUM-230 RADIUM-226 RADON-222 (3.8 DAYS TO DECAY FURTHER) *ALPHA PARTICLE POLONIUM-218 *ALPHA PARTICLE LEAD-214 BISMUTH-214 POLONIUM-214 *ALPHA PARTICLE LEAD-210 BISMUTH-210 POLONIUM-210 *ALPHA PARTICLE LEAD-206 *ALPHA RADIATION IS A PARTICLE RELEASED WHEN THE NUCLEUS KICKS OUT 2 NEWTRONS AND 2 PROTRONS.
The Health risks of radon gas have been clearly recognized by organizations such as the National Academy of Sciences, the Centers for Disease Control and the Prevention, the World Health Organization, the American lung Association, the American Medical Association and EPA. Radon is a known human carcinogen and is estimated to be the second leading causes of lung cancer. Only smoking causes more lung cancer deaths. The EPA estimates that radon causes between 7,000 - 30,000 lung cancer deaths each year in the U.S. By comparison, roughly 23,000 people in this country die from the results of drunk driving accidents, 4,400 die of injuries caused by firs, and 1,000 are killed in airplane crashes annually. Scientists agree that the risks associated with radon increase as the concentration and length of exposure increase. Smoking combined with radon is an especially serious health risk.