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 came back home two days later. This xenon gas treatment, which is supposed to help climbers avoid altitude sickness, has caused disagreement and is being investigated by officials in Nepal. Before the climb, the team trained in special tents that simulate high altitude and had xenon gas treatment at a clinic in Germany. Furtenbach believes that spending less time on the mountain could reduce environmental problems, such as less human waste. However, Furtenbach also stated that the xenon gas was never used in Nepal, and he claims he can show it is safe for climbers.