To Everest and back in one week, but on gas: British climbers use xenon for record ascent

“They were treated with xenon in Germany and trained in hypoxia tents for several months,” Furtenbach told Reuters and the Associated Press.

“Xenon helps with acclimatisation and protects against altitude sickness,” he asserted.

Before setting foot in Nepal, the climbers reportedly underwent xenon treatment at a specialised clinic in Germany and trained for months in hypoxia tents that simulate high-altitude conditions, enabling them to drastically reduce the time usually spent at Everest Base Camp and its surrounding acclimatisation routes.

The team flew from London to Kathmandu on May 16 and summited Everest (8,849 metres) early on May 21.

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Notably, this is one of the fastest ascents of the mountain ever recorded.

Furtenbach said the use of xenon also reduced the overall environmental impact. “Shorter expeditions mean less garbage, less human waste, and fewer resources used,” he said.

However, not everyone in the mountaineering community supports the approach.

American climber Adrian Ballinger called the method a “stunt” and said it did not align with the traditional spirit of mountaineering. “But if that’s the experience they’re proud of, it’s their choice,” he said.

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Nepal, which issued 468 climbing permits for Everest this season, does not have specific rules about acclimatisation. Permits are valid for 90 days, and most climbers spend weeks at base camp and higher camps to prepare for the summit.