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86. RadonName: Radon
At ordinary temperatures radon is a colourless gas. When cooled below the freezing point, radon exhibits a brilliant phosphorescence which becomes yellow as the temperature is lowered and orange-red at the temperature of liquid air. The main hazard is from inhalation of the element and its decay products which are collected on dust in the air. Recently, radon buildup in homes from the surrounding soil and rocks has become a safety issue and some areas around the world test homes for radon gas. It is the heaviest known gas. Radon is present in some spring waters. Radon is a decay product of the radium salts used in the luminous paint of the numerals. Radon was a popular additive in products like toothpaste, hair creams and even food items in the early 20th century, due to its supposed curative powers. Radon was subsequently removed when its carcinogenic properties were discovered. However, there are still radon baths and hot springs in Japan. These baths promote radon by saying that it cures illnesses like hypertension and hemorrhoids. Radon (named for radium) was discovered in 1900 by Friedrich Ernst Dorn, who called it radium emanation. In 1908 William Ramsay and Robert Whytlaw-Gray, who named it niton (Latin nitens meaning "shining"; symbol Nt), isolated it, determined its density and that it was the heaviest known gas. It has been called radon since 1923. Radon is a carcinogenic gas. Radon is a radioactive material and must be handled with care at all times. It is hazardous to inhale this element since it emits alpha particles. Also, its solid decay products, and their respective products, tend to form a fine dust which can easily enter the airways and become permanently stuck in lung tissue, producing heavy localized exposure. Rooms where radium, actinium, or thorium are stored should be well-ventilated in order to prevent build-up in the air. The build-up of radon is a potential health hazard in uranium and some lead mines. Build-up of radon in homes has also been a more recent health concern and many lung cancer cases are attributed to radon exposure each year. Indoors radon is estimated to cause about 21,000 lung cancer deaths per year in the U.S. Radon is the second leading cause of lung cancer in the U.S. today. About 12% of lung cancers in the U.S. are potentially attributable to radon, although these statistics are, when examined closely, somewhat dubious. Because of the long developmental time for lung cancers in general, and the multiple sources for lung cancer, it is difficult (if not impossible) to full discern what impact domestic radon has on the overall number of lung cancers. Quick links
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