Lukas Furtenbach, a well-known mountain guide, led a British team to climb Mount Everest very quickly, using a special xenon gas treatment. The team left London on May 16th, reached the top on May 21st, and returned home two days later. This xenon gas treatment, which helps protect climbers from getting sick at high altitudes, has caused some debate and is now being investigated by Nepalese climbing officials. Before the climb, the climbers prepared by training in special tents that simulate high altitudes and had xenon gas treatment at a clinic in Germany. Furtenbach believes that spending less time on the mountain could help the environment, for example, by reducing human waste. He also says that the xenon gas treatment was never actually used in Nepal, and he can prove that it is safe for climbers.