From the beginning, life has evolved in the presence of natural background ionizing radiation. There are three principal types and sources of radiation that occur on earth. The first of which are cosmic rays, which impinge on the Earth from outer space. The second is from terrestrial radiation, which are released by the disintegration of radium, thorium, uranium, and other radioactive minerals in the Earth's crust. Finally, there is internal radiation, which are emitted by the disintegration of potassium-40, carbon-14, and other radioactive isotopes that are normally present within living cells. .
There is an average total dose of radiation received from all three sources by a person residing at sea level, which is approximately .91 mSv per year1. However, a dose twice this size may be received by a person residing at a higher elevation where cosmic rays are more intense. A person living in a geographic region where the radium content of the soil is relatively high can also receive twice the dose of .91 mSv per year. In the latter form is what this paper is going to be concerned with. Radon a chemical element is a heavy, radioactive, noble gas. It is generated by the radioactive decay of radium. It is a colorless, odorless, tasteless gas, seven and a half times heavier than air and more than one hundred times heavier that hydrogen. .
Radon is rare in nature because its isotopes are all short-lived and because radium, its source, is a scarce element. The atmosphere contains traces of radon near the ground as a result of seepage from soil and rocks, all of which contain minute quantities of radium. Radium consequently, occurs as a natural decay product of uranium present in various types of rocks.
By the late 1980's, naturally occurring radon gas had come to be recognized as a potentially serious health hazard. The gas, arising from soil and rocks, seeps through the foundations, basements, or piping of buildings and can accumulate in the air of houses that are poorly ventilated.