What is radon?

Indoor Radon is the second leading cause of lung cancer in the United States and the leading cause among non-smokers. Protect your family. Test your home. During the month of January, EPA works to raise the public's awareness about radon and the importance of testing for radon -- especially in homes and schools. The EPA, working in concert with Federal, State, and local governments as well as volunteer organizations, conducts many different programs to educate Americans about the indoor radon health threat. About 1 in 15 homes has high radon levels. If you haven't tested your home, do it now during National Radon Action Month. If you have further questions about Radon, please call your state radon contact (just click on your state), or call the National Radon Information Line at: 1-800-SOS-RADON [1-800-767-7236]

A colorless, radioactive, inert gaseous element formed by the radioactive decay of radium. It is used as a radiation source in radiotherapy and to produce neutrons for research. Its most stable isotope is Rn 222 with a half-life of 3.82 days. Atomic number 86; melting point -71掳C; boiling point -61.8掳C; specific gravity (solid) 4. See table at element.

It is formed naturally in areas where the bed rock is made up of granite. Cornwall in the UK is an example of an area where there is a lot of Radon gas released naturally - where as here in Buckinghamshire where we have sedimentary chalk under clay there are no radon hotspots.

Radon is a radioactive gas that arises from the natural radioactive decay of radium, which is a natural decay product of uranium. Scientifically, 鈥渞adon鈥?is known to be radon-222, the most abundant isotope of the element radon. The terms radon and radon-222 are often used interchangeably when referring to the indoor radon issue.



As a noble gas, radon is colorless, odorless and chemically inert and cannot be detected by human senses. Also, since radon is not chemically reactive with most materials, it will move freely as a gas. Radon has a radiological half-life of 3.8 days, and can move substantial distances from its point of origin.



The first four radioactive isotopes formed as radon decays are polonium-218, lead-214, bismuth-214 and polonium-214. They are commonly referred to as 鈥渞adon daughters鈥?or 鈥渞adon progeny.鈥? These short-lived isotopes are not gases but are chemically active solids. They are present in any environment where radon is found and, like radon, cannot be detected by human senses.



The earth is the source of all radon gas in our atmosphere. Uranium is a natural part of the earth鈥檚 crust. Therefore, radium and radon are also naturally present (as noted above). Since uranium and radium concentrations vary throughout the earth鈥檚 crust, radon concentrations will also vary. The amount of radon gas that escapes into the atmosphere is dependent on the depth at which it is formed and the permeability of the surrounding earth. Radon formed in the top 10 meters of soil and rock provides the largest component of radon entering the atmosphere. Because they are metallic particulates, radon daughters formed in the soil will not escape.



The second most important contributor to atmospheric radon is emanation from groundwater. Underground radon is readily carried in groundwater and when this groundwater surfaces, most of the radon is released to the atmosphere.



Other sources of atmospheric radon are very small contributors and are largely due to human activities. For example, there are radium-rich industrial by-products spread upon the earth, and sometimes construction materials are produced from raw materials that contain uranium or radium.



Worldwide, over 2.5 billion curies of radon are emitted annually into the atmosphere. Atmospheric dilution results in a typical outdoor level of between 0.2 and 0.7 picocuries per liter (pCi/l). However, wide variations do exist.