Radon is a colorless, odorless radioactive gas formed by the natural decay of uranium in soil. It can build up in any kind of building, including homes, offices and schools, but prolonged exposure is most likely at home. Radon can also be present in drinking water and in building materials. Radon exposure is a leading cause of lung cancer.
Radon From Soil
According to the Environmental Protection Agency, or EPA, radon formed in soil beneath buildings may rise into structures through cracks and holes in their foundations. These entry points may include cracks in walls or floors, construction joints, gaps around pipes or in suspended floors and cavities located within walls. Nearly one in 15 homes in the United States are thought to have elevated radon levels. Reducing exposure to radon in homes can be accomplished by sealing entry routes and by reversing pressure differences between indoor spaces and outdoor soil, according to the World Health Organization, or WHO.
Radon in Drinking Water
Although soil is the most common source of radon, the gas may also be found in well water. According to the WHO, radon in groundwater is due primarily to the decay of the radium in soil and rock, rather than dissolved radium in water. Scale on iron pipes in water distribution sytems may also be a source of radon. The health risk associated with inhaling radon released from water is greater than that associated with drinking radon-contaminated water.
Radon in Building Materials
A less common source of radon exposure is certain building materials, which, according to the EPA, may give off radon but are rarely an important source of radon buildup. Building materials containing alum shale may be a source of radon, according to the WHO.
Health Effects of Radon
The EPA estimates that radon exposure causes approximately 21,000 lung cancer deaths annually, making it the second leading cause of lung cancer after smoking. The chance of developing lung cancer from radon exposure is increased with higher radon levels, greater length of exposure, and in current or former smokers.
Testing for Radon
You can measure radon levels in your home using either inexpensive home radon test kits or a professional tester. The EPA recommends initially conducting a short-term test--two to 90 days--and if radon levels exceed 4 Pico curies per liter of air, or pCi/L, a follow-up test should be conducted. The average normal indoor radon level is approximately 1.3 pCi/L,
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