Radon Health Hazards

Radon222 is a colorless, odorless, radioactive gas that forms from the decay of naturally occurring Uranium238. Since Uranium238 occurs in soil and rock throughout the world, radon exposure is universal; radon is present not only indoors but outdoors. Radon exposure in homes is largely a result of radon-contaminated gas rising from the soil. This makes it an unusual indoor air pollutant in that it has a natural source, (Frumkin and Jonathan, 2001).

Radon escapes from the ground into the outdoor air. It is diluted to low concentrations and is not a concern. However, radon that enters an enclosed space, such as a home, can sometimes accumulate to high levels, (CMHC, 1997).

Any home may have elevated radon levels. Gaseous radon can enter a home through foundation cracks, openings for pipes, wall/floor joints, chimneys, sumps, unfinished crawl spaces, and hollow, concrete block foundations. Once inside, the gas may be trapped and accumulated, (Jeanette and Michael, 1996).

Comparative risk analyses performed in the United States by numerous states and the federal government ranked residential radon exposure as one of the most serious environmental hazards, (Johnson, 2000). It is estimated to be the second leading cause of lung cancer after cigarette smoking. The excess of lung cancer caused by inhalation of radon can be detected in epidemiological studies. It has been suggested that radon may also cause other types of cancer, for example, leukaemia, (NRPB, 2000).

Within buildings, radon levels are usually highest in the basement due to its proximity to the ground from which the radon-containing soil gas diffuses (Marcinowski et. al., 1994). Building materials are the second source as the importance after soil for the indoor radon level, (Cosma et. al., 2000). Certain building materials may be more "radon-tight" and may help reduce exposure in areas where radon levels are high, (Keller et. al., 2001).

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