Lukas Furtenbach, a famous mountain guide, led a British team on a very fast climb of Mount Everest, 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 is designed to protect climbers from altitude sickness, but it has caused some discussion and is now being investigated by Nepalese climbing officials. Before the climb, the climbers got ready by training in special tents that simulate high-altitude conditions and by having xenon gas treatment at a German clinic. Furtenbach believes that spending less time on the mountain could help reduce harm to the environment, like less human waste. He also says that xenon gas treatment has never been used in Nepal, but he is sure he can prove it is safe for climbers.