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, reached the top on May 21, and came home two days later. This xenon gas helps climbers not get sick when they are very high up. But some people are worried about it, and officials in Nepal are checking if it is safe. The climbers got ready by training in special tents and using the xenon gas in a clinic in Germany. Furtenbach says that if climbers spend less time on the mountain, it could be better for the environment because there would be less rubbish. He also says that the xenon gas was never used in Nepal, and he can show that it is safe for climbers.