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Disregarding hypoxia, what is the minimum air pressure that the human body can tolerate?

(i.e. at what air pressure would the blood start to boil, or skin start to burst, or whatever else might happen that would kill you but isn't related to oxygen?)

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Can you separate lack of oxygen from low pressure? –  kmm Apr 21 at 22:22
    
@kmm: I don't see why not. Just because there's not enough oxygen reaching the brain doesn't mean your blood would start boiling or your skin would start bursting... –  Mehrdad Apr 21 at 23:04
    
I think one cannot really separate the lack of oxygen from air pressure. Because the inside pressure balance the outside pressure, if the pressure is low outside, one cannot inhale lots of air without lung injury. Similarly, a scuba diver always inhale air at the pressure associated with its depth. (In consequence divers absorb much more oxygen (and consume more air) in deep water than in shallow water). You may eventually separate air pressure from oxygen if you consider someone who put a single arm or leg in a artificially very low pressure environment. –  Remi.b Apr 23 at 9:00
    
@Remi.b: I don't see what's so hard about separating the two. Let me reword the question for you. Let's pretend the human body did not need oxygen/respiration at all, i.e. whatever you breathed in was exactly equal to whatever was breathed out (with no O2 or CO2 or anything else added or removed). What would be the minimum pressure it could survive in in that case? (If you're saying this has never been measured because, perhaps, it is impossible to measure, then please post that as an answer.) –  Mehrdad Apr 23 at 9:09
    
You might be interested to know what happen to our body in a vacuum. It does not tell you "the minimum pressure under which we can survive if we were to assume we don't need oxygen" but it might give you some sense of what you're looking for. –  Remi.b Apr 23 at 9:23

1 Answer 1

At sea level, where atmospheric pressure is 1 atm and oxygen is about 21% the partial pressure of oxygen is enough to saturate hemoglobin.

The lowest tolerable pressure of air is about 0.47 atm (475 millibars of atmospheric pressure) - recorded at 5950m altitude.

At about 0.35 atm (less than 356 millibars at around 8000m) life is impossible. Pulmonary and cerebral edema lead to death.

Source: Wikipedia, Effects of high altitude on humans

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You've got at least one number wrong. The "Death zone" at Mt Everest is considered to start at about 8000 meters, and the pressure there is about 0.75 atm. See engineeringtoolbox.com/air-altitude-pressure-d_462.html –  jarlemag Apr 21 at 22:52
    
Just to clarify, I didn't mean that the "Death zone" altitude is the answer to the question, just that your altitude and pressure numbers don't match. Also, I couldn't find those numbers in the linked article. –  jarlemag Apr 21 at 23:00
    
@jarlemag In the article Death zone pressure was in milibars. I converted it to atm. –  Cornelius Apr 22 at 8:08
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Sorry, my mistake. I mistook feet and meters in the table. There's still one mistake though: The lowest tolerable pressure (inhabited for two years) and 475 millibar figure is at the height of 5950 m. 5100 m is the height of the highest permanent settlement. –  jarlemag Apr 22 at 12:57

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