I've read somewhere that above 2500 meters (8,202 ft) 20% of climbers report having had altitude sickness. IIRC they also wrote that 40% of climbers report altitude sickness above 3500 meters (11,500 ft) though I'm unsure about the latter value. I wonder at what altitude the percentage approaches 50% and more. Preferrably in mid-latitude mountains (such as the Alps, the New Zealand Southern Alps, the Cascade range, northern Colorado or the Caucasus) because at the mid-latitudes the atmospheric pressure at an elevation should be about the same as at the pressure altitude on an aircraft's altimeter. Answer may include values from high altitude chambers.
At what elevation do 50% or higher percentages of mountaineers report symptoms of altitude sickness?
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5I don't think there's a single number, as age, gender, physical condition, home elevation, rate of ascension and a lot of other factors come into play. This paper covers the Alps and Colorado as well as Nepal.– anongoodnurseCommented Sep 13, 2023 at 19:02
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3It can be unclear what a person means by "altitude sickness". That is, what I commonly experience on Day 1 and think of as merely an annoying headache and a feeling of blahness, which clears up overnight or in at most a day, may be somebody else's definition of altitude sickness. Is this technically altitude sickness? Perhaps, but I don't think it is helpful to lump together minor, transitory symptoms with the sort of symptoms that demand a quick retreat to a lower elevation. Calling the latter "acute altitude sickness" is helpful, but (continued)– ab2Commented Sep 13, 2023 at 20:42
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(continued) without more info on symptoms, "altitude sickness" by itself can mean almost anything.– ab2Commented Sep 13, 2023 at 20:46
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1It isn't useful to compare mountaineering with the pressure in an aircraft, where the passengers are inactive, and the crew are accustomed to the reduced pressure.– Weather VaneCommented Sep 13, 2023 at 21:28
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1I live near 6000 feet. The only time in my life I definitely have had mild altitude sickness was when I drove to a campground at around 8000 feet. That night I had had a wicked headache and mild nausea. Before and after I've been much higher, even under similar conditions (short drive to a campground - just was up over 11,000 feet). The difference in that one time? I'd spent about two weeks at sea level, then returned home for a week before going camping. So even for one person, how and when altitude symptoms start depends on many variables.– Jon CusterCommented Sep 18, 2023 at 12:42
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1 Answer
It's not definable to the level of precision you seem to be imagining, but probably somewhere around 16,000' (~4,900 meters). It depends on what criteria you use. For some references, see the introductory section of this paper: Dallimore, J., & Rowbotham, E. C. (2009). Incidence of Acute Mountain Sickness in Adolescents. Wilderness & Environmental Medicine, 20(3), 221–224. doi:10.1580/07-weme-or-119r3.1 https://sci-hub.se/10.1580/07-WEME-OR-119R3.1
There is a background rate of something like 10%, which is just because people often feel bad while they're in the mountains because of factors like lack of sleep, caffeine withdrawal, and so on: https://pubmed.ncbi.nlm.nih.gov/22441083/
