Lukas Furtenbach, a famous mountain guide, helped a British team climb Mount Everest very fast. They used a special gas called xenon. The team left London on May 16, got to the top on May 21, and came back home two days later. This xenon gas helps climbers not get sick when they are high up on mountains. But some people are worried about it, and officials in Nepal are checking it. Before the climb, the team practiced in special tents and used the xenon gas at a clinic in Germany. Furtenbach thinks that spending less time on the mountain is better for nature. He also says that the xenon gas was not used in Nepal, and he can show that it is safe for climbers.