How much pressure can the human body tolerate before living is impossible (e.g. skin begins to rupture, etc.)?
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1$\begingroup$ If high pressure is equal within the human body and the atmosphere no skin will rupture. $\endgroup$– UweCommented Dec 7, 2018 at 17:36
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1$\begingroup$ Interesting question, but what are the implications for space exploration? $\endgroup$– TypeIACommented Dec 7, 2018 at 22:35
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3 Answers
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The answers are found in the SCUBA diving world. Diving is interesting in this sense in that 10m is roughly an increase in pressure of 1atm.
In general, you wont see humans doing well above 30atm. 300m is a "holy grail" of sorts for deep diving. Only a handful of people have ever gone that far down. And by a handful, I mean it's been done seven times, total.
NCBI provides a short paper with a theoretical limit of 1000m for humans, based on data we have collected from saturation divers to date. That would be 100atm of pressure.
Somewhere in between is the claimed record for deep diving which is roughly 600m.
Slightly higher than that, we find synthetic testing of Hydreliox. This was done in a chamber compressed to a simulated 700m (70atm). It was found that there were issues with hydrogen narcosis at depths below 500m, no matter how they tweaked the mix.
I cannot find the link, but I came across a fascinating link months ago which described the different gases you can breathe and how deep you can go. At somewhere in the 40m range, you start suffering from nitrogen narcosis, so its beneficial to use a mix without nitrogen to go lower, such as heliox. However, at extreme depths, you start running into helium toxicity issues, and adding a little nitrogen in helps with that. Yes, I said helium toxicity. At high enough pressures, the noble gasses start to kill us, and of the noble gasses, we use helium at those depths because it kills us the least!
answered Dec 7, 2018 at 21:47
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$\begingroup$ +1 for a great answer, but it might be nice to point out why it's so surprising that Helium becomes toxic. Or at least add a link. Depressingly I can't actually even find anything about helium toxicity on the web. $\endgroup$– DRFCommented Dec 7, 2018 at 22:52
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2$\begingroup$ @DRF It's really strange to hear that a noble gas has toxic effects. It had something to do with the nervous system, but I forget what it was. And, like you, I can't find links. It doesn't matter until something like 1000m, and there's not a whole lot of web-indexed content on what happens to the body at that point! $\endgroup$ Commented Dec 7, 2018 at 23:05
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4$\begingroup$ Right I assume the strangeness comes from the fact that noble gasses are inert and so you would not expect them to interact in any way other than possibly displacing stuff. $\endgroup$– DRFCommented Dec 7, 2018 at 23:08
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$\begingroup$ These only seven dives to more than 300 m do not include the dives of professional saturation divers using a divers bell at constant pressure for the transfer from surface to ground and back. These seven dives are done with decompression in the water not using a divers bell and saturation diving. $\endgroup$– UweCommented Dec 8, 2018 at 14:31
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1$\begingroup$ Look for "High-pressure nervous syndrome" - that's what the helium toxicity is usually found under :) $\endgroup$– GerinoCommented Nov 28, 2023 at 13:50
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How much pressure can the human body tolerate before living is impossible
The maximum tolerated pressure by a diver. It can be over 65 atm or bars. See: Saturation_diving
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$\begingroup$ 65 bar is possible using very special breathing gas mixtures only. Using compressed air is impossible at such a pressure. $\endgroup$– UweCommented Dec 7, 2018 at 17:39
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There does not appear to be a maximum pressure. We hit a limit as Cort Ammon says but that is a matter of what we can breathe, not an actual pressure limit. You get poisoned by going too deep, not crushed or torn apart.
Note that this does not preclude a hypothetical liquid breathing system. While we do not know how to build something yet (there are liquids that can carry enough oxygen and are non-toxic. The problem is it would take too much effort for our lungs to move it in and out) this is a technological limit, not a theoretical limit.
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$\begingroup$ If the viscosity of the high pressure gas is to much for the chest muscles, the exchange of oxygen and carbon dioxide may be impaired. $\endgroup$– UweCommented Jun 6, 2022 at 17:45
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1$\begingroup$ @Uwe No--high pressure liquid. The current human depth limit is due to toxicity of the breathing gases as pressure goes up, go deep enough and there's no gas that's safe to breathe. However, there are liquids capable of dissolving enough gas--there have been demonstrations of small animals surviving them. However, square-cube interferes, human lungs wouldn't be able to inhale/exhale it. The problem is mass, not viscosity. $\endgroup$ Commented Jun 6, 2022 at 23:15
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1$\begingroup$ This is it. The question aims at mechanical effects of high pressure ("skin rupture etc.") which do not exist: The human body is very much like a water balloon with a few bones in it which is happy at any depth, even though it is mechanically very weak. The problem are the chemical and biological effects of gases at high partial pressures. If, as a gedankenexperiment, the blood could be oxygenated outside the body in an artificial lung, the problems would disappear, I suppose. $\endgroup$ Commented Feb 14, 2023 at 22:15
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1$\begingroup$ @Peter-ReinstateMonica You still have the problem with there being no gas which is safe in the lungs. Perhaps you could fill the lungs with fluid and handle gas exchange by other means. $\endgroup$ Commented Feb 15, 2023 at 19:50