Radon

Radon was discovered around 1899 to 1900 through the work of Ernest Rutherford, Robert Owens and Friedrich Ernst Dorn, who traced a radioactive gas emanating from radium and thorium; William Ramsay and Robert Whytlaw-Gray isolated and characterised it in 1910. Its name derives from radium, from which it forms by decay. Radon is a colourless, odourless, radioactive noble gas, the heaviest of that family, and the principal natural source of radiation dose to the general public.

Seeping from uranium in rocks and soil, radon can build up in basements and mines, where it is a leading cause of lung cancer after smoking, so that testing and ventilation against the invisible gas are routine safety measures; it was once sealed in tiny tubes for radiotherapy. Despite radon's well-documented cancer risk, a number of European spas, including Bad Gastein in Austria and Jachymov in the Czech Republic, continue to offer radon inhalation and bathing treatments marketed for arthritis and other chronic pain, a practice with roots in early twentieth-century radioactivity enthusiasm and one that mainstream oncology and radiation-safety bodies regard as unsupported by solid evidence and medically unwise, an echo of the same era's radium quackery persisting into contemporary wellness tourism.

Radon was for a time called niton, from the Latin nitens, shining, because in its early study the radioactive gas made phosphorescent materials glow, and it was also known simply as radium emanation, the exhalation of radium. The modern name ties it firmly to its radioactive parent. The element has no ancient or alchemical tradition, being a product of the discovery of radioactivity, and its cultural significance is almost entirely a matter of health: seeping from uranium-bearing rocks and soil, radon can accumulate in buildings, where it is a leading cause of lung cancer after smoking, so that testing and ventilating against this invisible, odourless gas has become a routine concern of modern homes and mines. Its glowing early name survives only as a historical curiosity.

In the United States the Environmental Protection Agency recommends corrective action in homes testing above four picocuries per litre of air, and the standard fix, sub-slab depressurisation, simply draws the gas from beneath a building's foundation and vents it safely above the roofline before it can seep indoors, a low-tech solution to a genuinely serious and entirely invisible health hazard. Radon testing kits are inexpensive and widely available, and public-health agencies in radon-prone regions routinely encourage homeowners to test every few years.