🕷️ Crawler Inspector

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Raw Queries and Responses

1. Shard Calculation

Query:

Response:

Calculated Shard: 84 (from laksa195)

2. Crawled Status Check

Query:

curl -X POST \
  'http://laksa084.int.ahrefs:8124/' \
  -H 'Content-Type: text/plain' \
  -H 'X-ClickHouse-Database: crawler3' \
  -H 'Authorization: Basic YXBpOg==' \
  -d 'SELECT getAhrefsURLFromUnparsed(src_unparsed) AS found_url, ifNull(toUnixTimestamp(download_stamp), 0) AS crawl_time, ifNull(toUnixTimestamp(props_url_first_seen), 0) AS first_indexed_time, download_http_code AS http_code, src_unparsed AS src_unparsed, src_root_hash AS src_root_hash, history_drop_reason AS history_drop_reason, meta_title AS meta_title, meta_descriptions AS meta_descriptions, attrs_boilerpipe_text AS attrs_boilerpipe_text, attrs_markdown AS attrs_markdown, attrs_readable_markdown AS attrs_readable_markdown, meta_canonical AS meta_canonical FROM crawler3.page_info_local FINAL PREWHERE (src_root_hash, src_unparsed) IN ((getAhrefsRootHashFromUnparsed(getAhrefsUnparsedNoserviceFromURL(\'https://www.nytimes.com/2025/05/27/world/europe/mount-everest-xenon-gas-nepal-uk-climbers.html\')), getAhrefsUnparsedNoserviceFromURL(\'https://www.nytimes.com/2025/05/27/world/europe/mount-everest-xenon-gas-nepal-uk-climbers.html\'))) FORMAT JSONEachRow'

Response:

{"found_url":"https:\/\/www.nytimes.com\/2025\/05\/27\/world\/europe\/mount-everest-xenon-gas-nepal-uk-climbers.html","crawl_time":1772606774,"first_indexed_time":1748338639,"http_code":200,"src_unparsed":"com,nytimes!www,\/2025\/05\/27\/world\/europe\/mount-everest-xenon-gas-nepal-uk-climbers.html s443","src_root_hash":"4566504020376537684","history_drop_reason":null,"meta_title":"They Inhaled a Gas and Scaled Everest in Days. Is It the Future of Mountaineering? - The New York Times","meta_descriptions":["A group of British men went from London to the summit of Everest and back in less than a week with the help of xenon gas. Mountaineers and the Nepalese government weren’t pleased."],"attrs_boilerpipe_text":"Four British climbers pose on the summit of Mount Everest on Wednesday after preparing for the climb with xenon gas.\nCredit...\nSandro Gromen\/Associated Press\nA group of British men went from London to the summit of Everest and back in less than a week with the help of xenon gas. Mountaineers and the Nepalese government weren’t pleased.\nFour British climbers pose on the summit of Mount Everest on Wednesday after preparing for the climb with xenon gas.\nCredit...\nSandro Gromen\/Associated Press\nJonathan Wolfe\nand\nBhadra Sharma\nJonathan Wolfe reported from London, and Bhadra Sharma from Kathmandu, Nepal.\nMay 27, 2025\nClimbing Mount Everest typically takes weeks, with most of that time spent at the foot of the mountain adjusting to the thin air. But four British men last week shrank that timeline dramatically, traveling from London to the summit and back in less than a week, according to the organizer of their expedition.\nThey skipped the adjustment period, in part, by inhaling a secret weapon: xenon gas.\nTheir feat has roiled the world of mountaineering and prompted an investigation by the Nepalese government, as use of the gas is fiercely debated. Some research has shown that xenon can quickly acclimatize people to high altitudes, even as some experts say the benefits, if any, are negligible and the side effects of its use remain unclear.\nOrganizers said the gas was key to the speed of the climb, but their approach has prompted a broader debate that strikes at the core of mountaineering: Should scaling Mount Everest, one of sporting’s greatest accomplishments, be made easier — available to more people during a quick vacation — with the help of a performance enhancer?\n“It is a provocation, especially for traditional mountaineers, who feel bad about this idea that you can climb Everest in less than a week,” Lukas Furtenbach, who organized the exhibition, said in a phone interview from the base of the mountain. “This showed that it can work.”\nMr. Furtenbach said that beginning in 2026 he planned to offer two-week round-trip excursions to Mount Everest using xenon gas, cutting the typical time needed to scale the mountain by several weeks.\n“This can be the future of commercially guided mountaineering on Mount Everest,” he said.\nWith Xenon, ‘you feel better.’\nFor those who live at lower elevations and have traveled to the mountains, the discomfort of altitude sickness is all too clear. Symptoms include nausea, headaches and disrupted sleep, and in some cases it can lead to brain swelling, or even death.\nAs you go higher, less oxygen is absorbed into the bloodstream with each breath. That is why so many people who climb Everest use supplemental oxygen.\nXenon, an odorless gas, has been known for years to activate a molecule called the hypoxia-inducible factor, which is also turned on when people acclimate to low oxygen, said Hugh Montgomery, a professor of intensive care medicine at University College London and a mountaineer who led an expedition to Mount Everest to study how humans respond to low oxygen.\n“So what these people claim to have done,” he said, “is basically found a way to switch on the adaptation to low oxygen levels.”\nImage\nUsed oxygen cylinders and cans collected en route to Mount Everest at a waste facility in Kathmandu, Nepal, last year.\nCredit...\nSanjog Manandhar\/Associated Press\nThe group took what was known from medical science, he said, “and have now applied it, recreationally, to sport mountaineering.”\nProfessor Montgomery said scientists were still unsure how xenon triggers this response.\nWhile some doctors have used the gas in the past to “precondition” patients to low oxygen levels — for example, before major heart surgery — the practice hasn’t really caught on because “it hasn’t been as protective as one would hope,” he said.\nMike Shattock, a professor of cellular cardiology at King’s College London, said “xenon probably does very little and there is virtually no reputable scientific evidence that it makes any difference.”\nExperts also cautioned that self-medicating with xenon, which has the effects of anesthesia, could lead to overdose or death, and more study was needed to understand how the gas works and its use in mountaineering.\nOn Mount Everest, the weeks of training and acclimation on the lower levels of the mountain are typically required to survive the “death zone,” the area above 26,000 feet where the air is particularly thin.\nThe British group, which included four former special forces members, took a different approach.\nAbout 10 weeks before the expedition, the men began sleeping in hypoxic tents, which lower oxygen levels in the air and gradually acclimatized the hikers to conditions on Mount Everest, Mr. Furtenbach said.\nWhile hypoxic tents have been used by some climbers for years, the big innovation for the British expedition came two weeks before the excursion, when the men flew to Limburg, Germany, outside Frankfurt, where a doctor, Michael Fries, had been experimenting with inhaled gases in his clinic.\nThe men wore masks hooked up to ventilators as an anesthesiologist slowly introduced higher levels of xenon into their systems.\nMr. Furtenbach, who has tried xenon gas on his own mountaineering trips since 2020, said that after the treatment, users experienced enhanced breathing and the sensation of more lung volume, and “when you do your workout or training, you feel better.”\nAfter arriving at the base of Everest, the British group climbed to the summit in less than three days, which Mr. Furtenbach said was one of the fastest times for a group that hadn’t acclimatized on the mountain. (According to the Nepalese government, the record for the fastest climb overall is held by\nLakpa Gelu\n, a Sherpa, who reached the top of the mountain in just under 11 hours.)\nThe rapid climb by the British expedition and the use of the gas caught the eye of the Nepalese government, and the fallout has been swift.\nThe use of the gas is ‘against climbing ethics.’\nHimal Gautam, the director of Nepal’s tourism department, which is responsible for regulating expeditions on the nation’s mountains, said in an interview that using the gas was “against climbing ethics,” and that it would hurt the country’s tourism industry and the Sherpas who help climbers by reducing their time on the mountain.\nMr. Gautam said his department was looking into the use of the gas by the British climbers, one of whom, Alistair Carns, is also a member of Parliament.\nIn an interview, Mr. Carns said that his expedition had been in touch with the ministry, and clarified with the department that it had not taken the gas on the mountain.\nHe added that many people who want to climb Mount Everest don’t have the time to spend multiple weeks acclimating.\n“The reality is if I had six to eight weeks to climb Everest, I would, but I’m a government minister and I don’t have time,” he said. “What we’ve done is we’ve proven that you can reduce the timeline safely.”\nOthers in the mountaineering community have warned against the use of the gas.\nIn January, the International Climbing and Mountaineering Federation, a global network that promotes and protects the sport,\nreleased a statement\nthat said there was no evidence that xenon gas improved performance, adding that “inappropriate use can be dangerous.”\nThe federation noted that xenon has been on the World Anti-Doping Agency’s list of banned substances since 2014 and is not approved in all countries.\n“From a medical point of view, off-label use without a scientific basis and with unknown health risks must be rejected,” the statement said.\nImage\nThe area of Everest Base Camp in Nepal earlier this year.\nCredit...\nPurnima Shrestha\/Reuters\nMr. Furtenbach argued that his expeditions were still using Sherpas — five accompanied the British climbers to the summit — and that shorter times on the mountain were safer, as they reduce the chance that climbers will be exposed to other health threats, including avalanches, hypothermia or falls.\nHe said the prohibition of the gas by the World Anti-Doping Agency didn’t apply to mountaineering because it is not a regulated competitive sport.\nUse of the gas gets at a core question about why people climb big hills in the first place, Professor Montgomery said.\n“Is it really a good idea that we can all have what we want, when we want, as quick as we want?” he asked. “Are we missing out on the sacrifice you sometimes have to make to get the achievement?”\n“I’m not a critic,” he added. “But maybe just bagging every hill at speed means you miss out on the joy you could have had.”\nJonathan Wolfe\nis a Times reporter based in London, covering breaking news.\nA version of this article appears in print on\nJune 1, 2025\n, Section A, Page 26 of the New York edition with the headline: Up Everest in a Flash, Assisted by Xenon Gas\n.\nOrder Reprints\n|\nToday’s Paper\n|\nSubscribe\nAdvertisement\nSKIP ADVERTISEMENT","attrs_markdown":"[Europe](https:\/\/www.nytimes.com\/section\/world\/europe)\\|They Inhaled a Gas and Scaled Everest in Days. Is It the Future of Mountaineering?\n\nhttps:\/\/www.nytimes.com\/2025\/05\/27\/world\/europe\/mount-everest-xenon-gas-nepal-uk-climbers.html\n\n- Share full article\n- 721\n\n![Four mountaineers in black outwear. They are wearing masks and one holds a British flag over his head.](https:\/\/static01.nyt.com\/images\/2025\/05\/24\/multimedia\/00xp-everest-drug-climbers-tvwp\/00xp-everest-drug-climbers-tvwp-articleLarge.jpg?quality=75&auto=webp&disable=upscale)\n\nFour British climbers pose on the summit of Mount Everest on Wednesday after preparing for the climb with xenon gas.Credit...Sandro Gromen\/Associated Press\n\n[Skip to content](https:\/\/www.nytimes.com\/2025\/05\/27\/world\/europe\/mount-everest-xenon-gas-nepal-uk-climbers.html#site-content)[Skip to site index](https:\/\/www.nytimes.com\/2025\/05\/27\/world\/europe\/mount-everest-xenon-gas-nepal-uk-climbers.html#site-index)\n\nSearch & Section Navigation\n\nSection Navigation\n# They Inhaled a Gas and Scaled Everest in Days. Is It the Future of Mountaineering?\nA group of British men went from London to the summit of Everest and back in less than a week with the help of xenon gas. Mountaineers and the Nepalese government weren’t pleased.\n\nFour British climbers pose on the summit of Mount Everest on Wednesday after preparing for the climb with xenon gas.Credit...Sandro Gromen\/Associated Press\n\nSupported by\n\n[SKIP ADVERTISEMENT](https:\/\/www.nytimes.com\/2025\/05\/27\/world\/europe\/mount-everest-xenon-gas-nepal-uk-climbers.html#after-sponsor)\n\n- Share full article\n- 721\n\nBy [Jonathan Wolfe](https:\/\/www.nytimes.com\/by\/jonathan-wolfe) and Bhadra Sharma\n\nJonathan Wolfe reported from London, and Bhadra Sharma from Kathmandu, Nepal.\n\n- May 27, 2025\n\n[Leer en español](https:\/\/www.nytimes.com\/es\/2025\/05\/27\/espanol\/estados-unidos\/everest-alpinismo-gas-xenon.html \"Read in Spanish\")\n\nClimbing Mount Everest typically takes weeks, with most of that time spent at the foot of the mountain adjusting to the thin air. But four British men last week shrank that timeline dramatically, traveling from London to the summit and back in less than a week, according to the organizer of their expedition.\n\nThey skipped the adjustment period, in part, by inhaling a secret weapon: xenon gas.\n\nTheir feat has roiled the world of mountaineering and prompted an investigation by the Nepalese government, as use of the gas is fiercely debated. Some research has shown that xenon can quickly acclimatize people to high altitudes, even as some experts say the benefits, if any, are negligible and the side effects of its use remain unclear.\n\nOrganizers said the gas was key to the speed of the climb, but their approach has prompted a broader debate that strikes at the core of mountaineering: Should scaling Mount Everest, one of sporting’s greatest accomplishments, be made easier — available to more people during a quick vacation — with the help of a performance enhancer?\n\n“It is a provocation, especially for traditional mountaineers, who feel bad about this idea that you can climb Everest in less than a week,” Lukas Furtenbach, who organized the exhibition, said in a phone interview from the base of the mountain. “This showed that it can work.”\n\nMr. Furtenbach said that beginning in 2026 he planned to offer two-week round-trip excursions to Mount Everest using xenon gas, cutting the typical time needed to scale the mountain by several weeks.\n\n“This can be the future of commercially guided mountaineering on Mount Everest,” he said.\n\n## With Xenon, ‘you feel better.’\nFor those who live at lower elevations and have traveled to the mountains, the discomfort of altitude sickness is all too clear. Symptoms include nausea, headaches and disrupted sleep, and in some cases it can lead to brain swelling, or even death.\n\nAs you go higher, less oxygen is absorbed into the bloodstream with each breath. That is why so many people who climb Everest use supplemental oxygen.\n\nXenon, an odorless gas, has been known for years to activate a molecule called the hypoxia-inducible factor, which is also turned on when people acclimate to low oxygen, said Hugh Montgomery, a professor of intensive care medicine at University College London and a mountaineer who led an expedition to Mount Everest to study how humans respond to low oxygen.\n\n“So what these people claim to have done,” he said, “is basically found a way to switch on the adaptation to low oxygen levels.”\n\nImage\n\n![A collection of discarded oxygen cylinders and cans collected en route to Mount Everest at a waste facility in Kathmandu, Nepal.](https:\/\/static01.nyt.com\/images\/2025\/05\/24\/multimedia\/00xp-everest-drug-used-oxygen-zbqw\/00xp-everest-drug-used-oxygen-zbqw-articleLarge.jpg?quality=75&auto=webp&disable=upscale)\n\nUsed oxygen cylinders and cans collected en route to Mount Everest at a waste facility in Kathmandu, Nepal, last year.Credit...Sanjog Manandhar\/Associated Press\n\nThe group took what was known from medical science, he said, “and have now applied it, recreationally, to sport mountaineering.”\n\nProfessor Montgomery said scientists were still unsure how xenon triggers this response.\n\nWhile some doctors have used the gas in the past to “precondition” patients to low oxygen levels — for example, before major heart surgery — the practice hasn’t really caught on because “it hasn’t been as protective as one would hope,” he said.\n\nMike Shattock, a professor of cellular cardiology at King’s College London, said “xenon probably does very little and there is virtually no reputable scientific evidence that it makes any difference.”\n\nExperts also cautioned that self-medicating with xenon, which has the effects of anesthesia, could lead to overdose or death, and more study was needed to understand how the gas works and its use in mountaineering.\n\nOn Mount Everest, the weeks of training and acclimation on the lower levels of the mountain are typically required to survive the “death zone,” the area above 26,000 feet where the air is particularly thin.\n\nThe British group, which included four former special forces members, took a different approach.\n\nAbout 10 weeks before the expedition, the men began sleeping in hypoxic tents, which lower oxygen levels in the air and gradually acclimatized the hikers to conditions on Mount Everest, Mr. Furtenbach said.\n\nWhile hypoxic tents have been used by some climbers for years, the big innovation for the British expedition came two weeks before the excursion, when the men flew to Limburg, Germany, outside Frankfurt, where a doctor, Michael Fries, had been experimenting with inhaled gases in his clinic.\n\nThe men wore masks hooked up to ventilators as an anesthesiologist slowly introduced higher levels of xenon into their systems.\n\nMr. Furtenbach, who has tried xenon gas on his own mountaineering trips since 2020, said that after the treatment, users experienced enhanced breathing and the sensation of more lung volume, and “when you do your workout or training, you feel better.”\n\nAfter arriving at the base of Everest, the British group climbed to the summit in less than three days, which Mr. Furtenbach said was one of the fastest times for a group that hadn’t acclimatized on the mountain. (According to the Nepalese government, the record for the fastest climb overall is held by [Lakpa Gelu](https:\/\/nepalhimalpeakprofile.org\/mount-everest-record-holders), a Sherpa, who reached the top of the mountain in just under 11 hours.)\n\nThe rapid climb by the British expedition and the use of the gas caught the eye of the Nepalese government, and the fallout has been swift.\n\n## The use of the gas is ‘against climbing ethics.’\nHimal Gautam, the director of Nepal’s tourism department, which is responsible for regulating expeditions on the nation’s mountains, said in an interview that using the gas was “against climbing ethics,” and that it would hurt the country’s tourism industry and the Sherpas who help climbers by reducing their time on the mountain.\n\nMr. Gautam said his department was looking into the use of the gas by the British climbers, one of whom, Alistair Carns, is also a member of Parliament.\n\nIn an interview, Mr. Carns said that his expedition had been in touch with the ministry, and clarified with the department that it had not taken the gas on the mountain.\n\nHe added that many people who want to climb Mount Everest don’t have the time to spend multiple weeks acclimating.\n\n“The reality is if I had six to eight weeks to climb Everest, I would, but I’m a government minister and I don’t have time,” he said. “What we’ve done is we’ve proven that you can reduce the timeline safely.”\n\nOthers in the mountaineering community have warned against the use of the gas.\n\nIn January, the International Climbing and Mountaineering Federation, a global network that promotes and protects the sport, [released a statement](https:\/\/www.theuiaa.org\/statement-on-xenon-and-high-altitude-mountaineering\/) that said there was no evidence that xenon gas improved performance, adding that “inappropriate use can be dangerous.”\n\nThe federation noted that xenon has been on the World Anti-Doping Agency’s list of banned substances since 2014 and is not approved in all countries.\n\n“From a medical point of view, off-label use without a scientific basis and with unknown health risks must be rejected,” the statement said.\n\nImage\n\n![The gray area of Everest Base Camp in Nepal. Orange tents dot the landscape against a backdrop of the snowy mountains. ](https:\/\/static01.nyt.com\/images\/2025\/05\/24\/multimedia\/00xp-everest-drug-basecamp-zwqk\/00xp-everest-drug-basecamp-zwqk-articleLarge.jpg?quality=75&auto=webp&disable=upscale)\n\nThe area of Everest Base Camp in Nepal earlier this year.Credit...Purnima Shrestha\/Reuters\n\nMr. Furtenbach argued that his expeditions were still using Sherpas — five accompanied the British climbers to the summit — and that shorter times on the mountain were safer, as they reduce the chance that climbers will be exposed to other health threats, including avalanches, hypothermia or falls.\n\nHe said the prohibition of the gas by the World Anti-Doping Agency didn’t apply to mountaineering because it is not a regulated competitive sport.\n\nUse of the gas gets at a core question about why people climb big hills in the first place, Professor Montgomery said.\n\n“Is it really a good idea that we can all have what we want, when we want, as quick as we want?” he asked. “Are we missing out on the sacrifice you sometimes have to make to get the achievement?”\n\n“I’m not a critic,” he added. “But maybe just bagging every hill at speed means you miss out on the joy you could have had.”\n\nMount Everest\n\n[![]()Drones Will Do Some Schlepping for Sherpas on Mount Everest March 18, 2025](https:\/\/www.nytimes.com\/2025\/03\/18\/world\/asia\/mount-everest-drones.html)\n\n[![]()Why Mount Everest Is Growing Taller Every Year Sept. 30, 2024](https:\/\/www.nytimes.com\/2024\/09\/30\/science\/mount-everest-tallest-growing.html)\n\n[![]()‘It Was Like a Zoo’: Death on an Unruly, Overcrowded Everest May 26, 2019](https:\/\/www.nytimes.com\/2019\/05\/26\/world\/asia\/mount-everest-deaths.html)\n\n[Jonathan Wolfe](https:\/\/www.nytimes.com\/by\/jonathan-wolfe) is a Times reporter based in London, covering breaking news.\n\nA version of this article appears in print on June 1, 2025, Section A, Page 26 of the New York edition with the headline: Up Everest in a Flash, Assisted by Xenon Gas. [Order Reprints](https:\/\/nytimes.wrightsmedia.com\/) \\| [Today’s Paper](https:\/\/www.nytimes.com\/section\/todayspaper) \\| [Subscribe](https:\/\/www.nytimes.com\/subscriptions\/Multiproduct\/lp8HYKU.html?campaignId=48JQY)\n\nRead 721 comments\n\n- Share full article\n- 721\n## Related Content\nAdvertisement\n\n[SKIP ADVERTISEMENT](https:\/\/www.nytimes.com\/2025\/05\/27\/world\/europe\/mount-everest-xenon-gas-nepal-uk-climbers.html#after-bottom)\n## Site Index\n## Site Information Navigation\n- [© 2026 The New York Times Company](https:\/\/help.nytimes.com\/hc\/en-us\/articles\/115014792127-Copyright-Notice)\n\n- [NYTCo](https:\/\/www.nytco.com\/)\n- [Contact Us](https:\/\/help.nytimes.com\/hc\/en-us\/articles\/115015385887-Contact-The-New-York-Times)\n- [Accessibility](https:\/\/help.nytimes.com\/hc\/en-us\/articles\/115015727108-Accessibility)\n- [Work with us](https:\/\/www.nytco.com\/careers\/)\n- [Advertise](https:\/\/advertising.nytimes.com\/)\n- [T Brand Studio](https:\/\/advertising.nytimes.com\/custom-content\/)\n- [Privacy Policy](https:\/\/help.nytimes.com\/hc\/en-us\/articles\/10940941449492-The-New-York-Times-Company-Privacy-Policy)\n- [Cookie Policy](https:\/\/www.nytimes.com\/privacy\/cookie-policy)\n- [Terms of Service](https:\/\/help.nytimes.com\/hc\/en-us\/articles\/115014893428-Terms-of-Service)\n- [Terms of Sale](https:\/\/help.nytimes.com\/hc\/en-us\/articles\/115014893968-Terms-of-Sale)\n- [Site Map](https:\/\/www.nytimes.com\/sitemap\/)\n- [Canada](https:\/\/www.nytimes.com\/ca\/)\n- [International](https:\/\/www.nytimes.com\/international\/)\n- [Help](https:\/\/help.nytimes.com\/hc\/en-us)\n- [Subscriptions](https:\/\/www.nytimes.com\/subscription?campaignId=37WXW)","attrs_readable_markdown":"![Four mountaineers in black outwear. They are wearing masks and one holds a British flag over his head.](https:\/\/static01.nyt.com\/images\/2025\/05\/24\/multimedia\/00xp-everest-drug-climbers-tvwp\/00xp-everest-drug-climbers-tvwp-articleLarge.jpg?quality=75&auto=webp&disable=upscale)\n\nFour British climbers pose on the summit of Mount Everest on Wednesday after preparing for the climb with xenon gas.Credit...Sandro Gromen\/Associated Press\n\nA group of British men went from London to the summit of Everest and back in less than a week with the help of xenon gas. Mountaineers and the Nepalese government weren’t pleased.\n\nFour British climbers pose on the summit of Mount Everest on Wednesday after preparing for the climb with xenon gas.Credit...Sandro Gromen\/Associated Press\n\n[Jonathan Wolfe](https:\/\/www.nytimes.com\/by\/jonathan-wolfe) and Bhadra Sharma\n\nJonathan Wolfe reported from London, and Bhadra Sharma from Kathmandu, Nepal.\n\n- May 27, 2025\n\nClimbing Mount Everest typically takes weeks, with most of that time spent at the foot of the mountain adjusting to the thin air. But four British men last week shrank that timeline dramatically, traveling from London to the summit and back in less than a week, according to the organizer of their expedition.\n\nThey skipped the adjustment period, in part, by inhaling a secret weapon: xenon gas.\n\nTheir feat has roiled the world of mountaineering and prompted an investigation by the Nepalese government, as use of the gas is fiercely debated. Some research has shown that xenon can quickly acclimatize people to high altitudes, even as some experts say the benefits, if any, are negligible and the side effects of its use remain unclear.\n\nOrganizers said the gas was key to the speed of the climb, but their approach has prompted a broader debate that strikes at the core of mountaineering: Should scaling Mount Everest, one of sporting’s greatest accomplishments, be made easier — available to more people during a quick vacation — with the help of a performance enhancer?\n\n“It is a provocation, especially for traditional mountaineers, who feel bad about this idea that you can climb Everest in less than a week,” Lukas Furtenbach, who organized the exhibition, said in a phone interview from the base of the mountain. “This showed that it can work.”\n\nMr. Furtenbach said that beginning in 2026 he planned to offer two-week round-trip excursions to Mount Everest using xenon gas, cutting the typical time needed to scale the mountain by several weeks.\n\n“This can be the future of commercially guided mountaineering on Mount Everest,” he said.\n\n## With Xenon, ‘you feel better.’\nFor those who live at lower elevations and have traveled to the mountains, the discomfort of altitude sickness is all too clear. Symptoms include nausea, headaches and disrupted sleep, and in some cases it can lead to brain swelling, or even death.\n\nAs you go higher, less oxygen is absorbed into the bloodstream with each breath. That is why so many people who climb Everest use supplemental oxygen.\n\nXenon, an odorless gas, has been known for years to activate a molecule called the hypoxia-inducible factor, which is also turned on when people acclimate to low oxygen, said Hugh Montgomery, a professor of intensive care medicine at University College London and a mountaineer who led an expedition to Mount Everest to study how humans respond to low oxygen.\n\n“So what these people claim to have done,” he said, “is basically found a way to switch on the adaptation to low oxygen levels.”\n\nImage\n\n![A collection of discarded oxygen cylinders and cans collected en route to Mount Everest at a waste facility in Kathmandu, Nepal.](https:\/\/static01.nyt.com\/images\/2025\/05\/24\/multimedia\/00xp-everest-drug-used-oxygen-zbqw\/00xp-everest-drug-used-oxygen-zbqw-articleLarge.jpg?quality=75&auto=webp&disable=upscale)\n\nUsed oxygen cylinders and cans collected en route to Mount Everest at a waste facility in Kathmandu, Nepal, last year.Credit...Sanjog Manandhar\/Associated Press\n\nThe group took what was known from medical science, he said, “and have now applied it, recreationally, to sport mountaineering.”\n\nProfessor Montgomery said scientists were still unsure how xenon triggers this response.\n\nWhile some doctors have used the gas in the past to “precondition” patients to low oxygen levels — for example, before major heart surgery — the practice hasn’t really caught on because “it hasn’t been as protective as one would hope,” he said.\n\nMike Shattock, a professor of cellular cardiology at King’s College London, said “xenon probably does very little and there is virtually no reputable scientific evidence that it makes any difference.”\n\nExperts also cautioned that self-medicating with xenon, which has the effects of anesthesia, could lead to overdose or death, and more study was needed to understand how the gas works and its use in mountaineering.\n\nOn Mount Everest, the weeks of training and acclimation on the lower levels of the mountain are typically required to survive the “death zone,” the area above 26,000 feet where the air is particularly thin.\n\nThe British group, which included four former special forces members, took a different approach.\n\nAbout 10 weeks before the expedition, the men began sleeping in hypoxic tents, which lower oxygen levels in the air and gradually acclimatized the hikers to conditions on Mount Everest, Mr. Furtenbach said.\n\nWhile hypoxic tents have been used by some climbers for years, the big innovation for the British expedition came two weeks before the excursion, when the men flew to Limburg, Germany, outside Frankfurt, where a doctor, Michael Fries, had been experimenting with inhaled gases in his clinic.\n\nThe men wore masks hooked up to ventilators as an anesthesiologist slowly introduced higher levels of xenon into their systems.\n\nMr. Furtenbach, who has tried xenon gas on his own mountaineering trips since 2020, said that after the treatment, users experienced enhanced breathing and the sensation of more lung volume, and “when you do your workout or training, you feel better.”\n\nAfter arriving at the base of Everest, the British group climbed to the summit in less than three days, which Mr. Furtenbach said was one of the fastest times for a group that hadn’t acclimatized on the mountain. (According to the Nepalese government, the record for the fastest climb overall is held by [Lakpa Gelu](https:\/\/nepalhimalpeakprofile.org\/mount-everest-record-holders), a Sherpa, who reached the top of the mountain in just under 11 hours.)\n\nThe rapid climb by the British expedition and the use of the gas caught the eye of the Nepalese government, and the fallout has been swift.\n\n## The use of the gas is ‘against climbing ethics.’\nHimal Gautam, the director of Nepal’s tourism department, which is responsible for regulating expeditions on the nation’s mountains, said in an interview that using the gas was “against climbing ethics,” and that it would hurt the country’s tourism industry and the Sherpas who help climbers by reducing their time on the mountain.\n\nMr. Gautam said his department was looking into the use of the gas by the British climbers, one of whom, Alistair Carns, is also a member of Parliament.\n\nIn an interview, Mr. Carns said that his expedition had been in touch with the ministry, and clarified with the department that it had not taken the gas on the mountain.\n\nHe added that many people who want to climb Mount Everest don’t have the time to spend multiple weeks acclimating.\n\n“The reality is if I had six to eight weeks to climb Everest, I would, but I’m a government minister and I don’t have time,” he said. “What we’ve done is we’ve proven that you can reduce the timeline safely.”\n\nOthers in the mountaineering community have warned against the use of the gas.\n\nIn January, the International Climbing and Mountaineering Federation, a global network that promotes and protects the sport, [released a statement](https:\/\/www.theuiaa.org\/statement-on-xenon-and-high-altitude-mountaineering\/) that said there was no evidence that xenon gas improved performance, adding that “inappropriate use can be dangerous.”\n\nThe federation noted that xenon has been on the World Anti-Doping Agency’s list of banned substances since 2014 and is not approved in all countries.\n\n“From a medical point of view, off-label use without a scientific basis and with unknown health risks must be rejected,” the statement said.\n\nImage\n\n![The gray area of Everest Base Camp in Nepal. Orange tents dot the landscape against a backdrop of the snowy mountains. ](https:\/\/static01.nyt.com\/images\/2025\/05\/24\/multimedia\/00xp-everest-drug-basecamp-zwqk\/00xp-everest-drug-basecamp-zwqk-articleLarge.jpg?quality=75&auto=webp&disable=upscale)\n\nThe area of Everest Base Camp in Nepal earlier this year.Credit...Purnima Shrestha\/Reuters\n\nMr. Furtenbach argued that his expeditions were still using Sherpas — five accompanied the British climbers to the summit — and that shorter times on the mountain were safer, as they reduce the chance that climbers will be exposed to other health threats, including avalanches, hypothermia or falls.\n\nHe said the prohibition of the gas by the World Anti-Doping Agency didn’t apply to mountaineering because it is not a regulated competitive sport.\n\nUse of the gas gets at a core question about why people climb big hills in the first place, Professor Montgomery said.\n\n“Is it really a good idea that we can all have what we want, when we want, as quick as we want?” he asked. “Are we missing out on the sacrifice you sometimes have to make to get the achievement?”\n\n“I’m not a critic,” he added. “But maybe just bagging every hill at speed means you miss out on the joy you could have had.”\n\n[Jonathan Wolfe](https:\/\/www.nytimes.com\/by\/jonathan-wolfe) is a Times reporter based in London, covering breaking news.\n\nA version of this article appears in print on June 1, 2025, Section A, Page 26 of the New York edition with the headline: Up Everest in a Flash, Assisted by Xenon Gas. 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Meta Title	They Inhaled a Gas and Scaled Everest in Days. Is It the Future of Mountaineering? - The New York Times
Meta Description	A group of British men went from London to the summit of Everest and back in less than a week with the help of xenon gas. Mountaineers and the Nepalese government weren’t pleased.
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Boilerpipe Text	Four British climbers pose on the summit of Mount Everest on Wednesday after preparing for the climb with xenon gas. Credit... Sandro Gromen/Associated Press A group of British men went from London to the summit of Everest and back in less than a week with the help of xenon gas. Mountaineers and the Nepalese government weren’t pleased. Four British climbers pose on the summit of Mount Everest on Wednesday after preparing for the climb with xenon gas. Credit... Sandro Gromen/Associated Press Jonathan Wolfe and Bhadra Sharma Jonathan Wolfe reported from London, and Bhadra Sharma from Kathmandu, Nepal. May 27, 2025 Climbing Mount Everest typically takes weeks, with most of that time spent at the foot of the mountain adjusting to the thin air. But four British men last week shrank that timeline dramatically, traveling from London to the summit and back in less than a week, according to the organizer of their expedition. They skipped the adjustment period, in part, by inhaling a secret weapon: xenon gas. Their feat has roiled the world of mountaineering and prompted an investigation by the Nepalese government, as use of the gas is fiercely debated. Some research has shown that xenon can quickly acclimatize people to high altitudes, even as some experts say the benefits, if any, are negligible and the side effects of its use remain unclear. Organizers said the gas was key to the speed of the climb, but their approach has prompted a broader debate that strikes at the core of mountaineering: Should scaling Mount Everest, one of sporting’s greatest accomplishments, be made easier — available to more people during a quick vacation — with the help of a performance enhancer? “It is a provocation, especially for traditional mountaineers, who feel bad about this idea that you can climb Everest in less than a week,” Lukas Furtenbach, who organized the exhibition, said in a phone interview from the base of the mountain. “This showed that it can work.” Mr. Furtenbach said that beginning in 2026 he planned to offer two-week round-trip excursions to Mount Everest using xenon gas, cutting the typical time needed to scale the mountain by several weeks. “This can be the future of commercially guided mountaineering on Mount Everest,” he said. With Xenon, ‘you feel better.’ For those who live at lower elevations and have traveled to the mountains, the discomfort of altitude sickness is all too clear. Symptoms include nausea, headaches and disrupted sleep, and in some cases it can lead to brain swelling, or even death. As you go higher, less oxygen is absorbed into the bloodstream with each breath. That is why so many people who climb Everest use supplemental oxygen. Xenon, an odorless gas, has been known for years to activate a molecule called the hypoxia-inducible factor, which is also turned on when people acclimate to low oxygen, said Hugh Montgomery, a professor of intensive care medicine at University College London and a mountaineer who led an expedition to Mount Everest to study how humans respond to low oxygen. “So what these people claim to have done,” he said, “is basically found a way to switch on the adaptation to low oxygen levels.” Image Used oxygen cylinders and cans collected en route to Mount Everest at a waste facility in Kathmandu, Nepal, last year. Credit... Sanjog Manandhar/Associated Press The group took what was known from medical science, he said, “and have now applied it, recreationally, to sport mountaineering.” Professor Montgomery said scientists were still unsure how xenon triggers this response. While some doctors have used the gas in the past to “precondition” patients to low oxygen levels — for example, before major heart surgery — the practice hasn’t really caught on because “it hasn’t been as protective as one would hope,” he said. Mike Shattock, a professor of cellular cardiology at King’s College London, said “xenon probably does very little and there is virtually no reputable scientific evidence that it makes any difference.” Experts also cautioned that self-medicating with xenon, which has the effects of anesthesia, could lead to overdose or death, and more study was needed to understand how the gas works and its use in mountaineering. On Mount Everest, the weeks of training and acclimation on the lower levels of the mountain are typically required to survive the “death zone,” the area above 26,000 feet where the air is particularly thin. The British group, which included four former special forces members, took a different approach. About 10 weeks before the expedition, the men began sleeping in hypoxic tents, which lower oxygen levels in the air and gradually acclimatized the hikers to conditions on Mount Everest, Mr. Furtenbach said. While hypoxic tents have been used by some climbers for years, the big innovation for the British expedition came two weeks before the excursion, when the men flew to Limburg, Germany, outside Frankfurt, where a doctor, Michael Fries, had been experimenting with inhaled gases in his clinic. The men wore masks hooked up to ventilators as an anesthesiologist slowly introduced higher levels of xenon into their systems. Mr. Furtenbach, who has tried xenon gas on his own mountaineering trips since 2020, said that after the treatment, users experienced enhanced breathing and the sensation of more lung volume, and “when you do your workout or training, you feel better.” After arriving at the base of Everest, the British group climbed to the summit in less than three days, which Mr. Furtenbach said was one of the fastest times for a group that hadn’t acclimatized on the mountain. (According to the Nepalese government, the record for the fastest climb overall is held by Lakpa Gelu , a Sherpa, who reached the top of the mountain in just under 11 hours.) The rapid climb by the British expedition and the use of the gas caught the eye of the Nepalese government, and the fallout has been swift. The use of the gas is ‘against climbing ethics.’ Himal Gautam, the director of Nepal’s tourism department, which is responsible for regulating expeditions on the nation’s mountains, said in an interview that using the gas was “against climbing ethics,” and that it would hurt the country’s tourism industry and the Sherpas who help climbers by reducing their time on the mountain. Mr. Gautam said his department was looking into the use of the gas by the British climbers, one of whom, Alistair Carns, is also a member of Parliament. In an interview, Mr. Carns said that his expedition had been in touch with the ministry, and clarified with the department that it had not taken the gas on the mountain. He added that many people who want to climb Mount Everest don’t have the time to spend multiple weeks acclimating. “The reality is if I had six to eight weeks to climb Everest, I would, but I’m a government minister and I don’t have time,” he said. “What we’ve done is we’ve proven that you can reduce the timeline safely.” Others in the mountaineering community have warned against the use of the gas. In January, the International Climbing and Mountaineering Federation, a global network that promotes and protects the sport, released a statement that said there was no evidence that xenon gas improved performance, adding that “inappropriate use can be dangerous.” The federation noted that xenon has been on the World Anti-Doping Agency’s list of banned substances since 2014 and is not approved in all countries. “From a medical point of view, off-label use without a scientific basis and with unknown health risks must be rejected,” the statement said. Image The area of Everest Base Camp in Nepal earlier this year. Credit... Purnima Shrestha/Reuters Mr. Furtenbach argued that his expeditions were still using Sherpas — five accompanied the British climbers to the summit — and that shorter times on the mountain were safer, as they reduce the chance that climbers will be exposed to other health threats, including avalanches, hypothermia or falls. He said the prohibition of the gas by the World Anti-Doping Agency didn’t apply to mountaineering because it is not a regulated competitive sport. Use of the gas gets at a core question about why people climb big hills in the first place, Professor Montgomery said. “Is it really a good idea that we can all have what we want, when we want, as quick as we want?” he asked. “Are we missing out on the sacrifice you sometimes have to make to get the achievement?” “I’m not a critic,” he added. “But maybe just bagging every hill at speed means you miss out on the joy you could have had.” Jonathan Wolfe is a Times reporter based in London, covering breaking news. A version of this article appears in print on June 1, 2025 , Section A, Page 26 of the New York edition with the headline: Up Everest in a Flash, Assisted by Xenon Gas . Order Reprints \| Today’s Paper \| Subscribe Advertisement SKIP ADVERTISEMENT
Markdown	[Europe](https://www.nytimes.com/section/world/europe)\\|They Inhaled a Gas and Scaled Everest in Days. Is It the Future of Mountaineering? https://www.nytimes.com/2025/05/27/world/europe/mount-everest-xenon-gas-nepal-uk-climbers.html - Share full article - 721 ![Four mountaineers in black outwear. They are wearing masks and one holds a British flag over his head.](https://static01.nyt.com/images/2025/05/24/multimedia/00xp-everest-drug-climbers-tvwp/00xp-everest-drug-climbers-tvwp-articleLarge.jpg?quality=75&auto=webp&disable=upscale) Four British climbers pose on the summit of Mount Everest on Wednesday after preparing for the climb with xenon gas.Credit...Sandro Gromen/Associated Press [Skip to content](https://www.nytimes.com/2025/05/27/world/europe/mount-everest-xenon-gas-nepal-uk-climbers.html#site-content)[Skip to site index](https://www.nytimes.com/2025/05/27/world/europe/mount-everest-xenon-gas-nepal-uk-climbers.html#site-index) Search & Section Navigation Section Navigation # They Inhaled a Gas and Scaled Everest in Days. Is It the Future of Mountaineering? A group of British men went from London to the summit of Everest and back in less than a week with the help of xenon gas. Mountaineers and the Nepalese government weren’t pleased. Four British climbers pose on the summit of Mount Everest on Wednesday after preparing for the climb with xenon gas.Credit...Sandro Gromen/Associated Press Supported by [SKIP ADVERTISEMENT](https://www.nytimes.com/2025/05/27/world/europe/mount-everest-xenon-gas-nepal-uk-climbers.html#after-sponsor) - Share full article - 721 By [Jonathan Wolfe](https://www.nytimes.com/by/jonathan-wolfe) and Bhadra Sharma Jonathan Wolfe reported from London, and Bhadra Sharma from Kathmandu, Nepal. - May 27, 2025 [Leer en español](https://www.nytimes.com/es/2025/05/27/espanol/estados-unidos/everest-alpinismo-gas-xenon.html "Read in Spanish") Climbing Mount Everest typically takes weeks, with most of that time spent at the foot of the mountain adjusting to the thin air. But four British men last week shrank that timeline dramatically, traveling from London to the summit and back in less than a week, according to the organizer of their expedition. They skipped the adjustment period, in part, by inhaling a secret weapon: xenon gas. Their feat has roiled the world of mountaineering and prompted an investigation by the Nepalese government, as use of the gas is fiercely debated. Some research has shown that xenon can quickly acclimatize people to high altitudes, even as some experts say the benefits, if any, are negligible and the side effects of its use remain unclear. Organizers said the gas was key to the speed of the climb, but their approach has prompted a broader debate that strikes at the core of mountaineering: Should scaling Mount Everest, one of sporting’s greatest accomplishments, be made easier — available to more people during a quick vacation — with the help of a performance enhancer? “It is a provocation, especially for traditional mountaineers, who feel bad about this idea that you can climb Everest in less than a week,” Lukas Furtenbach, who organized the exhibition, said in a phone interview from the base of the mountain. “This showed that it can work.” Mr. Furtenbach said that beginning in 2026 he planned to offer two-week round-trip excursions to Mount Everest using xenon gas, cutting the typical time needed to scale the mountain by several weeks. “This can be the future of commercially guided mountaineering on Mount Everest,” he said. ## With Xenon, ‘you feel better.’ For those who live at lower elevations and have traveled to the mountains, the discomfort of altitude sickness is all too clear. Symptoms include nausea, headaches and disrupted sleep, and in some cases it can lead to brain swelling, or even death. As you go higher, less oxygen is absorbed into the bloodstream with each breath. That is why so many people who climb Everest use supplemental oxygen. Xenon, an odorless gas, has been known for years to activate a molecule called the hypoxia-inducible factor, which is also turned on when people acclimate to low oxygen, said Hugh Montgomery, a professor of intensive care medicine at University College London and a mountaineer who led an expedition to Mount Everest to study how humans respond to low oxygen. “So what these people claim to have done,” he said, “is basically found a way to switch on the adaptation to low oxygen levels.” Image ![A collection of discarded oxygen cylinders and cans collected en route to Mount Everest at a waste facility in Kathmandu, Nepal.](https://static01.nyt.com/images/2025/05/24/multimedia/00xp-everest-drug-used-oxygen-zbqw/00xp-everest-drug-used-oxygen-zbqw-articleLarge.jpg?quality=75&auto=webp&disable=upscale) Used oxygen cylinders and cans collected en route to Mount Everest at a waste facility in Kathmandu, Nepal, last year.Credit...Sanjog Manandhar/Associated Press The group took what was known from medical science, he said, “and have now applied it, recreationally, to sport mountaineering.” Professor Montgomery said scientists were still unsure how xenon triggers this response. While some doctors have used the gas in the past to “precondition” patients to low oxygen levels — for example, before major heart surgery — the practice hasn’t really caught on because “it hasn’t been as protective as one would hope,” he said. Mike Shattock, a professor of cellular cardiology at King’s College London, said “xenon probably does very little and there is virtually no reputable scientific evidence that it makes any difference.” Experts also cautioned that self-medicating with xenon, which has the effects of anesthesia, could lead to overdose or death, and more study was needed to understand how the gas works and its use in mountaineering. On Mount Everest, the weeks of training and acclimation on the lower levels of the mountain are typically required to survive the “death zone,” the area above 26,000 feet where the air is particularly thin. The British group, which included four former special forces members, took a different approach. About 10 weeks before the expedition, the men began sleeping in hypoxic tents, which lower oxygen levels in the air and gradually acclimatized the hikers to conditions on Mount Everest, Mr. Furtenbach said. While hypoxic tents have been used by some climbers for years, the big innovation for the British expedition came two weeks before the excursion, when the men flew to Limburg, Germany, outside Frankfurt, where a doctor, Michael Fries, had been experimenting with inhaled gases in his clinic. The men wore masks hooked up to ventilators as an anesthesiologist slowly introduced higher levels of xenon into their systems. Mr. Furtenbach, who has tried xenon gas on his own mountaineering trips since 2020, said that after the treatment, users experienced enhanced breathing and the sensation of more lung volume, and “when you do your workout or training, you feel better.” After arriving at the base of Everest, the British group climbed to the summit in less than three days, which Mr. Furtenbach said was one of the fastest times for a group that hadn’t acclimatized on the mountain. (According to the Nepalese government, the record for the fastest climb overall is held by [Lakpa Gelu](https://nepalhimalpeakprofile.org/mount-everest-record-holders), a Sherpa, who reached the top of the mountain in just under 11 hours.) The rapid climb by the British expedition and the use of the gas caught the eye of the Nepalese government, and the fallout has been swift. ## The use of the gas is ‘against climbing ethics.’ Himal Gautam, the director of Nepal’s tourism department, which is responsible for regulating expeditions on the nation’s mountains, said in an interview that using the gas was “against climbing ethics,” and that it would hurt the country’s tourism industry and the Sherpas who help climbers by reducing their time on the mountain. Mr. Gautam said his department was looking into the use of the gas by the British climbers, one of whom, Alistair Carns, is also a member of Parliament. In an interview, Mr. Carns said that his expedition had been in touch with the ministry, and clarified with the department that it had not taken the gas on the mountain. He added that many people who want to climb Mount Everest don’t have the time to spend multiple weeks acclimating. “The reality is if I had six to eight weeks to climb Everest, I would, but I’m a government minister and I don’t have time,” he said. “What we’ve done is we’ve proven that you can reduce the timeline safely.” Others in the mountaineering community have warned against the use of the gas. In January, the International Climbing and Mountaineering Federation, a global network that promotes and protects the sport, [released a statement](https://www.theuiaa.org/statement-on-xenon-and-high-altitude-mountaineering/) that said there was no evidence that xenon gas improved performance, adding that “inappropriate use can be dangerous.” The federation noted that xenon has been on the World Anti-Doping Agency’s list of banned substances since 2014 and is not approved in all countries. “From a medical point of view, off-label use without a scientific basis and with unknown health risks must be rejected,” the statement said. Image ![The gray area of Everest Base Camp in Nepal. Orange tents dot the landscape against a backdrop of the snowy mountains. ](https://static01.nyt.com/images/2025/05/24/multimedia/00xp-everest-drug-basecamp-zwqk/00xp-everest-drug-basecamp-zwqk-articleLarge.jpg?quality=75&auto=webp&disable=upscale) The area of Everest Base Camp in Nepal earlier this year.Credit...Purnima Shrestha/Reuters Mr. Furtenbach argued that his expeditions were still using Sherpas — five accompanied the British climbers to the summit — and that shorter times on the mountain were safer, as they reduce the chance that climbers will be exposed to other health threats, including avalanches, hypothermia or falls. He said the prohibition of the gas by the World Anti-Doping Agency didn’t apply to mountaineering because it is not a regulated competitive sport. Use of the gas gets at a core question about why people climb big hills in the first place, Professor Montgomery said. “Is it really a good idea that we can all have what we want, when we want, as quick as we want?” he asked. “Are we missing out on the sacrifice you sometimes have to make to get the achievement?” “I’m not a critic,” he added. “But maybe just bagging every hill at speed means you miss out on the joy you could have had.” Mount Everest [![]()Drones Will Do Some Schlepping for Sherpas on Mount Everest March 18, 2025](https://www.nytimes.com/2025/03/18/world/asia/mount-everest-drones.html) [![]()Why Mount Everest Is Growing Taller Every Year Sept. 30, 2024](https://www.nytimes.com/2024/09/30/science/mount-everest-tallest-growing.html) [![]()‘It Was Like a Zoo’: Death on an Unruly, Overcrowded Everest May 26, 2019](https://www.nytimes.com/2019/05/26/world/asia/mount-everest-deaths.html) [Jonathan Wolfe](https://www.nytimes.com/by/jonathan-wolfe) is a Times reporter based in London, covering breaking news. A version of this article appears in print on June 1, 2025, Section A, Page 26 of the New York edition with the headline: Up Everest in a Flash, Assisted by Xenon Gas. 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Readable Markdown	![Four mountaineers in black outwear. They are wearing masks and one holds a British flag over his head.](https://static01.nyt.com/images/2025/05/24/multimedia/00xp-everest-drug-climbers-tvwp/00xp-everest-drug-climbers-tvwp-articleLarge.jpg?quality=75&auto=webp&disable=upscale) Four British climbers pose on the summit of Mount Everest on Wednesday after preparing for the climb with xenon gas.Credit...Sandro Gromen/Associated Press A group of British men went from London to the summit of Everest and back in less than a week with the help of xenon gas. Mountaineers and the Nepalese government weren’t pleased. Four British climbers pose on the summit of Mount Everest on Wednesday after preparing for the climb with xenon gas.Credit...Sandro Gromen/Associated Press [Jonathan Wolfe](https://www.nytimes.com/by/jonathan-wolfe) and Bhadra Sharma Jonathan Wolfe reported from London, and Bhadra Sharma from Kathmandu, Nepal. - May 27, 2025 Climbing Mount Everest typically takes weeks, with most of that time spent at the foot of the mountain adjusting to the thin air. But four British men last week shrank that timeline dramatically, traveling from London to the summit and back in less than a week, according to the organizer of their expedition. They skipped the adjustment period, in part, by inhaling a secret weapon: xenon gas. Their feat has roiled the world of mountaineering and prompted an investigation by the Nepalese government, as use of the gas is fiercely debated. Some research has shown that xenon can quickly acclimatize people to high altitudes, even as some experts say the benefits, if any, are negligible and the side effects of its use remain unclear. Organizers said the gas was key to the speed of the climb, but their approach has prompted a broader debate that strikes at the core of mountaineering: Should scaling Mount Everest, one of sporting’s greatest accomplishments, be made easier — available to more people during a quick vacation — with the help of a performance enhancer? “It is a provocation, especially for traditional mountaineers, who feel bad about this idea that you can climb Everest in less than a week,” Lukas Furtenbach, who organized the exhibition, said in a phone interview from the base of the mountain. “This showed that it can work.” Mr. Furtenbach said that beginning in 2026 he planned to offer two-week round-trip excursions to Mount Everest using xenon gas, cutting the typical time needed to scale the mountain by several weeks. “This can be the future of commercially guided mountaineering on Mount Everest,” he said. ## With Xenon, ‘you feel better.’ For those who live at lower elevations and have traveled to the mountains, the discomfort of altitude sickness is all too clear. Symptoms include nausea, headaches and disrupted sleep, and in some cases it can lead to brain swelling, or even death. As you go higher, less oxygen is absorbed into the bloodstream with each breath. That is why so many people who climb Everest use supplemental oxygen. Xenon, an odorless gas, has been known for years to activate a molecule called the hypoxia-inducible factor, which is also turned on when people acclimate to low oxygen, said Hugh Montgomery, a professor of intensive care medicine at University College London and a mountaineer who led an expedition to Mount Everest to study how humans respond to low oxygen. “So what these people claim to have done,” he said, “is basically found a way to switch on the adaptation to low oxygen levels.” Image ![A collection of discarded oxygen cylinders and cans collected en route to Mount Everest at a waste facility in Kathmandu, Nepal.](https://static01.nyt.com/images/2025/05/24/multimedia/00xp-everest-drug-used-oxygen-zbqw/00xp-everest-drug-used-oxygen-zbqw-articleLarge.jpg?quality=75&auto=webp&disable=upscale) Used oxygen cylinders and cans collected en route to Mount Everest at a waste facility in Kathmandu, Nepal, last year.Credit...Sanjog Manandhar/Associated Press The group took what was known from medical science, he said, “and have now applied it, recreationally, to sport mountaineering.” Professor Montgomery said scientists were still unsure how xenon triggers this response. While some doctors have used the gas in the past to “precondition” patients to low oxygen levels — for example, before major heart surgery — the practice hasn’t really caught on because “it hasn’t been as protective as one would hope,” he said. Mike Shattock, a professor of cellular cardiology at King’s College London, said “xenon probably does very little and there is virtually no reputable scientific evidence that it makes any difference.” Experts also cautioned that self-medicating with xenon, which has the effects of anesthesia, could lead to overdose or death, and more study was needed to understand how the gas works and its use in mountaineering. On Mount Everest, the weeks of training and acclimation on the lower levels of the mountain are typically required to survive the “death zone,” the area above 26,000 feet where the air is particularly thin. The British group, which included four former special forces members, took a different approach. About 10 weeks before the expedition, the men began sleeping in hypoxic tents, which lower oxygen levels in the air and gradually acclimatized the hikers to conditions on Mount Everest, Mr. Furtenbach said. While hypoxic tents have been used by some climbers for years, the big innovation for the British expedition came two weeks before the excursion, when the men flew to Limburg, Germany, outside Frankfurt, where a doctor, Michael Fries, had been experimenting with inhaled gases in his clinic. The men wore masks hooked up to ventilators as an anesthesiologist slowly introduced higher levels of xenon into their systems. Mr. Furtenbach, who has tried xenon gas on his own mountaineering trips since 2020, said that after the treatment, users experienced enhanced breathing and the sensation of more lung volume, and “when you do your workout or training, you feel better.” After arriving at the base of Everest, the British group climbed to the summit in less than three days, which Mr. Furtenbach said was one of the fastest times for a group that hadn’t acclimatized on the mountain. (According to the Nepalese government, the record for the fastest climb overall is held by [Lakpa Gelu](https://nepalhimalpeakprofile.org/mount-everest-record-holders), a Sherpa, who reached the top of the mountain in just under 11 hours.) The rapid climb by the British expedition and the use of the gas caught the eye of the Nepalese government, and the fallout has been swift. ## The use of the gas is ‘against climbing ethics.’ Himal Gautam, the director of Nepal’s tourism department, which is responsible for regulating expeditions on the nation’s mountains, said in an interview that using the gas was “against climbing ethics,” and that it would hurt the country’s tourism industry and the Sherpas who help climbers by reducing their time on the mountain. Mr. Gautam said his department was looking into the use of the gas by the British climbers, one of whom, Alistair Carns, is also a member of Parliament. In an interview, Mr. Carns said that his expedition had been in touch with the ministry, and clarified with the department that it had not taken the gas on the mountain. He added that many people who want to climb Mount Everest don’t have the time to spend multiple weeks acclimating. “The reality is if I had six to eight weeks to climb Everest, I would, but I’m a government minister and I don’t have time,” he said. “What we’ve done is we’ve proven that you can reduce the timeline safely.” Others in the mountaineering community have warned against the use of the gas. In January, the International Climbing and Mountaineering Federation, a global network that promotes and protects the sport, [released a statement](https://www.theuiaa.org/statement-on-xenon-and-high-altitude-mountaineering/) that said there was no evidence that xenon gas improved performance, adding that “inappropriate use can be dangerous.” The federation noted that xenon has been on the World Anti-Doping Agency’s list of banned substances since 2014 and is not approved in all countries. “From a medical point of view, off-label use without a scientific basis and with unknown health risks must be rejected,” the statement said. Image ![The gray area of Everest Base Camp in Nepal. Orange tents dot the landscape against a backdrop of the snowy mountains. ](https://static01.nyt.com/images/2025/05/24/multimedia/00xp-everest-drug-basecamp-zwqk/00xp-everest-drug-basecamp-zwqk-articleLarge.jpg?quality=75&auto=webp&disable=upscale) The area of Everest Base Camp in Nepal earlier this year.Credit...Purnima Shrestha/Reuters Mr. Furtenbach argued that his expeditions were still using Sherpas — five accompanied the British climbers to the summit — and that shorter times on the mountain were safer, as they reduce the chance that climbers will be exposed to other health threats, including avalanches, hypothermia or falls. He said the prohibition of the gas by the World Anti-Doping Agency didn’t apply to mountaineering because it is not a regulated competitive sport. Use of the gas gets at a core question about why people climb big hills in the first place, Professor Montgomery said. “Is it really a good idea that we can all have what we want, when we want, as quick as we want?” he asked. “Are we missing out on the sacrifice you sometimes have to make to get the achievement?” “I’m not a critic,” he added. “But maybe just bagging every hill at speed means you miss out on the joy you could have had.” [Jonathan Wolfe](https://www.nytimes.com/by/jonathan-wolfe) is a Times reporter based in London, covering breaking news. A version of this article appears in print on June 1, 2025, Section A, Page 26 of the New York edition with the headline: Up Everest in a Flash, Assisted by Xenon Gas. 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