Bad Gastein is a spa town in Austria, situated in the middle of the National Park Hohe Tauern, at 1,000 metres above sea level. It hosted the Alpine ski world championship in 1958. It is located at the head of the Gastein valley, within the state of Salzburg, in which Salzburg is the major city. The name "Bad" means "spa" in the Gastein valley. The local thermal spring water earned the town its early fame. Theophratus Parcelsus (1493-1541) studied the Spring water to discover its secrets. Madame Curie(1867-1934) and Heinrich Mache(1876-1954) helped to discover that it contained radon.Radioactive water baths, with tighly controlled quantities of exposure, have been used for many years in many places. For example: Joachimsthal, Czech Republic and in traditional Japanese onsen in Misasa, Tottori prefecture.The Gasteiner-Heilstollen radon inhalation therapy began as a result of further investigation into the anecdotal experiences of silver miners who noticed improvements in symptoms from various ailments including arthritis (further citation needed). Ankylosing spondylitis (Also known as Bechterew's disease), in particular, has seen positive results from treatment at the Heilstollen. This style of therapy is also done in Kowary, Poland and in Boulder, Montana, United States. This treatment is covered by some Austrian and German health insurance plans. However, there is very little empirical evidence of any benefit to inhaling radon. For example, one of the few studies to test the efficacy of spa treatments for Ankylosing spondylitis found no statistically significant difference between a group that spent three weeks at Bad Gastein and a group that spent three weeks at a different spa without radon inhalation therapy. On the other hand, according to the U.S. National Institutes of Health, radon is the second leading cause of lung cancer in the United States, causing approximately 15,000 to 22,000 lung cancer deaths per year.