Radon was discovered in 1900 by a German chemist Friedrich E. Dorn. He called it radium emanation. What he discovered was radon-222, while a scarcer isotope, radon-220, was actually observed first, in 1899, by the British scientist, R.B. Owens, and the New Zealand scientist, Ernest Rutherford. In 1984 a nuclear plant worker in Pennsylvania discovered radioactivity on his clothing while exiting his place of work through a radiation detector. The source of the radiation was determined to be radon decay products on his clothing originating from his home. It wasn’t until then that the medical community became aware of the possible extent of radon related problems.
Rn is the chemical symbol for radon. It is a radioactive gas that occurs naturally and can be found in soils, rock, and water throughout the world. It has numerous different isotopes, but radon-220, and -222 are the most common. Radon is a gas that is created in the soils where uranium and radium are found. Since these elements can be found everywhere in the world any building has the potential for elevated levels of radon. The more uranium found in the soil, the higher the potential for elevated radon levels within that building.
Because radon is an inert (or noble) gas, meaning that it does not react or combine chemically with other substances except under certain special conditions, it can move up through the soil into the atmosphere, where it is easily diluted and presents little concern. However, when radon enters a building, it can build up and become a health concern
You cannot see or smell radon, and there is no way that your body can sense the presence of radon; however, it can have a detrimental effect on the inhabitants by increasing their likelihood of developing lung cancer.
The presence of Radon in the atmosphere or water is not due to any man made process or other source of pollution, but is mainly derived from uranium deposits in the soil. Uranium (Uranium-238) decays into a stable form of Lead through a series of steps which include the break down of uranium into radium (Radium-226) , which in turn decays into radon gas (Radon-222). Radium-226 and Radon-222 are present in almost all rock, soil and water.
Since radium 226 can be found in low concentrations in almost all rock and soil, it is not a question of “if”, but “how much” radon you really have. Radon is generated in rock and soil and it escapes into the atmosphere through cracks and spaces between the rocks and soil. This results in an average outdoor radon concentration of about 0.4 pCi/L (picocuries per liter of air). At these concentrations there is no real danger. However, if radon is allowed to seep into homes and buildings through cracks and holes in the foundations and walls, the concentration can build up to much higher levels, at which point research suggests there is a reason for concern.
The average indoor radon concentration is about 1.3 pCi/l. Radon concentrations in a home can very depending on several factors including; house design, soil conditions, local geology, and the weather, such as high or low atmospheric pressures, and warm or cold climate. For example, indoor radon levels increase substantially during the winter months. As indoor temperatures increase relative to the outside temperatures, a thermal effect occurs. The rising warm air within a building is displaced by cold denser outside air, some of which seeps in through the foundation cracks, vents, and holes from the underlying soils.
Furthermore, exhaust fans inside the house can create a lower (negative) pressure inside the home relative to the surrounding soil and air, and radon can actually be drawn into the building.