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, which has caused some disagreement. The team left London on May 16th, reached the top on May 21st, and came back home two days later. This xenon gas treatment is supposed to help climbers avoid getting sick from high altitudes, but it is now being investigated by officials in Nepal. Before the climb, the climbers trained in tents that had low oxygen and also had the 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 was never used in Nepal and that he can show it is safe for climbers.