Radon

Radon is a chemical element with the symbol Rn and atomic number 86. It is a radioactive, colorless, odorless, tasteless noble gas. It occurs naturally in minute quantities as an intermediate step in the normal radioactive decay chains through which thorium and uranium slowly decay into lead and various other short-lived radioactive elements. Radon itself is the immediate decay product of radium.

Characteristics

Radon is one of the densest substances that remains a gas under normal conditions. It is also the only gas under normal conditions that only has radioactive isotopes, and is considered a health hazard due to its radioactivity. Intense radioactivity has also hindered chemical studies of radon and only a few compounds are known.

Occurrence

Radon is usually found at low levels in soil, rock and water, and it can be released into the air. The gas can accumulate in buildings, especially in confined areas such as attics and basements. It can also be found in some spring waters and hot springs.

Health effects

Exposure to radon can cause lung cancer and is the second leading cause of lung cancer after cigarette smoking. The risk of lung cancer increases with the concentration of radon and the length of exposure. Radon is responsible for about 21,000 lung cancer deaths every year in the United States.

Measurement and mitigation

Methods of radon testing and mitigation are very effective and can reduce radon levels to below the recommended action level. The Environmental Protection Agency recommends that all homes be tested for radon.

See also

• Radon mitigation
• Radon therapy
• List of isotopes by radiation hazard

References

Radon Resources
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