The Earth emits radon gas as an element called radium-226, which is present in small amounts in almost all rocks and soils. The gas then rises out of the ground and into the atmosphere. Buildings can trap radon gas, and since it is an extremely heavy gas, it tends to concentrate in the lowest levels of buildings, such as the basements. Because there are health risks associated with radon gas, many homeowners test their homes for excessive levels.
Radon's Radioactivity
Radon-222, itself the result of the radioactive decay of radium-226, is also radioactive. It decays into thorium-218 and in the process emits alpha particles. Radon-220, a rarer form of the gas that results from the decay of thorium, also emits alpha particles. Alpha radiation is relatively low energy and does not penetrate skin very well, unlike beta and gamma radiation. Alpha particles consist of helium nuclei, 2 protons and 2 neutrons, that travel at very high speeds of up to one twentieth the speed of light for short distances. Though they do not penetrate skin easily, alpha particles do pose a health risk to people when they are emitted from materials that have been ingested or inhaled into the body.
Health Risks
Radon is classified as a human carcinogen, meaning it has the potential to cause cancer. External exposure to radon does not cause many problems, because alpha radiation does not penetrate the skin. However, radon can enter the body when someone drinks water or breathes air contaminated with radon. Radon dissolves easily in water, so most untreated water from natural sources has radon in it. The air within buildings built on soil with high radium concentration will likely have a high radon concentration as well.
Once inside the body, the radioactivity of radon causes damage to the deoxyribonucleic acids (DNA) inside your cells, which in turn can cause cancer. Lung tissue is particularly prone to cancer caused by radon. Scientists estimate that 90 percent of the cancer caused by radon is cancer of the lung, according to the Environmental Protection Agency (EPA).
Radon Levels
Radon levels are measured in picoCuries per liter of air (pCi/l). While any level above zero increases your risk of developing lung cancer, the EPA recommends that you take action when radon levels are greater than 4 pCi/l. Home inspectors can test the radon levels in your house, or you can buy radon detectors and do the test yourself. If the detectors reveal the radon level to be above 4 pCi/l in your home, you can have a radon mitigation system installed. These systems provide additional ventilation to your basement to purge radon before it builds up, thus eliminating the health risks.
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