Lukas Furtenbach, a famous mountain guide, led a British team on a very fast climb of Mount Everest. They used 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 getting sick at high altitudes. However, it has caused some discussion and is now being investigated by Nepalese climbing officials. The climbers prepared for the climb by training in special tents that simulate high altitude and by having the xenon gas treatment at a German clinic. Furtenbach believes that spending less time on the mountain could help the environment, for example, by reducing human waste. But Furtenbach also states that the xenon gas was never actually used in Nepal, and he believes he can prove it is safe for climbers.