An abundance of epidemiological and biological data and evidence has been established that shows the association between the development of lung cancer and exposure to radon. Radon is a radioactive gas that is naturally occurring on the earth when an element called uranium goes through a natural radioactive decay process. Radon can be found in water, rocks, and soil, and can easily make its way into the air an individual breathes. When radon escapes into the air outdoors, it rapidly dilutes and does not cause much of a problem or health concern.
However, radon concentrations become much higher indoors and in water treatment facilities, mines, and caves. When an individual inhales the radioactive particles of radon, they are deposited in the cells that make up the airway linings. These particles cause damage and may induce mutations or alterations in the cellular DNA. Repeated exposure to higher concentrations of radon indoors causes enough of these mutations or alterations that carcinogenesis takes place, and cancer develops in the lungs.