What air pressure can the human body survive?

In summary: On recreational diving oxygen is considered toxic beyond partial pressure of 1.6bar (~67m dive on air) and Nitrogen is starting to become toxic beyond partial pressure of 3.2bar (~ 30m dive on air). If one wants to go much deeper then that he have to use mixtures with lower % of Oxygen then air, lower % of Nitrogen then air and Helium. As far as I remember the world record for "dry" diving (inside a recompression chamber) is around 700meters (~70bars).In summary, at 10,000 psi a human could survive, but at less than half that pressure they would start to
  • #1
Les Lord
8
0
How much air pressure could a human survive in?
 
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  • #2
I believe that is dependent upon how long s/he has to acclimatize to the environment. You could slowly increase the pressure to 10,000 psi, and the guy will probably not suffer any (since the pressure within his body will rise equivalently with the outside air). Offer him 10,000 psi via a stick of dynamite, however, and his bodily response will be significantly less comfortable.
 
  • #3
And do you intend to have this person breathing air? A person can withstand perhaps 100 atmospheres of pressure if they aren't breathing air - divers do it. If they are breathing air, the limit is just a handful of atmospheres. Not sure exactly how many it takes before oxygen becomes toxic, though.
 
  • #4
I know that you cannot breath if you are under half a meter of water. I mean you cannot use a snorkel because of the pressure on your lungs.
 
  • #5
As Russ pointed out, divers are exposed to significant pressures. In fact, the main problem from a certain pressure onward is the toxicity or other unwanted biochemical effects of the breathing gasses, not the "mechanical" pressure itself. For instance, normal air becomes problematic beyond the 7 or 8 bars (although you can go to 15 bars if you're of the reckless kind). But that's because of nitrogen toxicity and oxygen toxicity, not because of the "pressure". If you adapt the breathing mixture (with helium), you can go to much higher pressures. There have been experiments with breathing liquids and then you can go to very high pressures indeed.
 
  • #6
vanesch said:
There have been experiments with breathing liquids and then you can go to very high pressures indeed.

Man, I'd forgotten about that. I haven't heard anything about it since the early 70's. Now I remember seeing that little rat playing around in the bottom of a tank full of super-oxygenated water. Didn't they at some point have even better results using some sort of fluorocarbon liquid in lieu of water?
And there's one technique, which as far as I know is still rated 'Top Secret' by the US government (as if I care), wherein pilots of high-performance aeroplanes saturate their bodies with xenon gas, then have the cockpit filled with the stuff. It supposedly let's one remain functional up to about 30 g's. I incorporated that into my SF novel over 25 years ago.
 
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  • #7
So can people breath in liquid oxygen? I mean apart from the fact it is cold, would it be possible?
 
  • #8
GrizzlyBat said:
So can people breath in liquid oxygen? I mean apart from the fact it is cold, would it be possible?

No. First off, as you mentioned, it is cold. One's respiratory tract and lungs would freeze solid. It would have to be evaporated first. Additionally, pure oxygen is deadly poisonous.
 
  • #9
Russ and Vanesch are both right. There are two problems: one is that at high enough partial pressure the N2 in air becomes toxic, and the other is that under these pressures air becomes heavier and just from mechanics breathing becomes very hard work. One can address these by going to heliox: a helium-oxygen mix, and the record is somewhere around 30 atmospheres.
 
  • #10
Danger said:
I incorporated that into my SF novel over 25 years ago.
You have not shared this with us. Still have signed editions?
 
  • #11
On recreational diving oxygen is considered toxic beyond partial pressure of 1.6bar (~67m dive on air) and Nitrogen is starting to become toxic beyond partial pressure of 3.2bar (~ 30m dive on air). If one wants to go much deeper then that he have to use mixtures with lower % of Oxygen then air, lower % of Nitrogen then air and Helium. As far as I remember the world record for "dry" diving (inside a recompression chamber) is around 700meters (~70bars).
 
  • #12
Danger said:
Now I remember seeing that little rat playing around in the bottom of a tank full of super-oxygenated water. Didn't they at some point have even better results using some sort of fluorocarbon liquid in lieu of water?
It works for rats because they can't choke (or vomit). You can't o it so easily in primates unless they are anesthetized because of the gag reflex.

The main practical problem for larger animals is that the carrier liquid contains such low concentrations of oxygen that you have to flow a huge volume through the lungs to get enough oxygen transferred - I forget the figures but it's something like a fire hose.
 
  • #13
DaveC426913 said:
You have not shared this with us. Still have signed editions?

I never submitted it for publication. It started as a grade 10 English project, and got out of hand. (Sort of like Greg's computer science project. :biggrin:) Although it is completed, as in done from beginning to end, it isn't finished. It's over 500 pages, but a large part of that should be excised. I have a couple of problems in that regard. One is that I choose my words very carefully (more than I do here), so it kind of hurts to delete them. The other is that I haven't been able to write a damned thing since I went on the anti-depressants for my ADD almost 10 years ago.
One of the major problems is that it's supposed to be SF, not Sci-Fi or Fantasy. I extrapolated modern technology to something that I foresaw for the future. By the time I finished writing it, some bastards invented my ideas so I had to keep going back and rewriting it to get ahead. To give you an indication of the time-frame, two of the main characters are a 65-year-old Korean war Sabre pilot and a 35-year-old Viet Nam F-4 pilot. Their wives are the other two main characters, who (essential to the plot) were in a USO performance near Phnom Penh.
If I do seek out a publisher, I'm seriously thinking of just adding an introduction page stating that it was written in the 70's and should be read with that in mind. :rolleyes:
 
  • #14
mgb_phys said:
It works for rats because they can't choke (or vomit). You can't o it so easily in primates unless they are anesthetized because of the gag reflex.

The main practical problem for larger animals is that the carrier liquid contains such low concentrations of oxygen that you have to flow a huge volume through the lungs to get enough oxygen transferred - I forget the figures but it's something like a fire hose.

I was unaware of that fact about rats. I'm pretty sure, though, that I also saw a man in a tank breathing super-oxygenated fluorocarbon. In the following interview, he said that he had a huge issue with getting that first lungful in, because he felt that he was drowning, but then acclimatized rapidly. Expelling the fluid at the end of the experiment was the worst part for him. This is something that I can't cite, though, because I can't remember where I saw it. It was either SciAm or some science show on TV, but it was decades ago and my memory works for a few minutes at best.
 
  • #15
Danger said:
Man, I'd forgotten about that. I haven't heard anything about it since the early 70's. Now I remember seeing that little rat playing around in the bottom of a tank full of super-oxygenated water. Didn't they at some point have even better results using some sort of fluorocarbon liquid in lieu of water?
And there's one technique, which as far as I know is still rated 'Top Secret' by the US government (as if I care), wherein pilots of high-performance aeroplanes saturate their bodies with xenon gas, then have the cockpit filled with the stuff. It supposedly let's one remain functional up to about 30 g's. I incorporated that into my SF novel over 25 years ago.

Isn't that from the movie "The Abyss"?
 
  • #16
maverick_starstrider said:
Isn't that from the movie "The Abyss"?

A: Which part of the quote?
B: I can't say, because I never saw 'The Abyss'.
 
  • #17
Danger said:
A: Which part of the quote?
B: I can't say, because I never saw 'The Abyss'.

I know that liquid breathing exist but the image of a rat being placed in the stuff and slowly looking like it is dying and then it starts breathing is from the movie The Abyss. First movie with CGI btw.

 
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  • #18
Danger said:
I never submitted it for publication. It started as a grade 10 English project, and got out of hand. (Sort of like Greg's computer science project. :biggrin:) Although it is completed, as in done from beginning to end, it isn't finished. It's over 500 pages, but a large part of that should be excised. I have a couple of problems in that regard. One is that I choose my words very carefully (more than I do here), so it kind of hurts to delete them. The other is that I haven't been able to write a damned thing since I went on the anti-depressants for my ADD almost 10 years ago.
One of the major problems is that it's supposed to be SF, not Sci-Fi or Fantasy. I extrapolated modern technology to something that I foresaw for the future. By the time I finished writing it, some bastards invented my ideas so I had to keep going back and rewriting it to get ahead. To give you an indication of the time-frame, two of the main characters are a 65-year-old Korean war Sabre pilot and a 35-year-old Viet Nam F-4 pilot. Their wives are the other two main characters, who (essential to the plot) were in a USO performance near Phnom Penh.
If I do seek out a publisher, I'm seriously thinking of just adding an introduction page stating that it was written in the 70's and should be read with that in mind. :rolleyes:
Will you let anyone read it? I would like to read it.
 
  • #19
DaveC426913 said:
Will you let anyone read it? I would like to read it.

Let me fix it first. :wink:
 
  • #20
Danger said:
And there's one technique, which as far as I know is still rated 'Top Secret' by the US government (as if I care), wherein pilots of high-performance aeroplanes saturate their bodies with xenon gas, then have the cockpit filled with the stuff. It supposedly let's one remain functional up to about 30 g's. I incorporated that into my SF novel over 25 years ago.
I read a long time ago that xenon gas was deadly poisonous, at least that is what the San Francisco Chronical science editor wrote, after he toured the Lawrence Livermore Lab nuclear reactor during an open house a while back.
(see http://en.wikipedia.org/wiki/Nuclear_poison)
 
  • #21
Bob S said:
I read a long time ago that xenon gas was deadly poisonous
I'll have to look into that. The guy who told me about it was a US government subcontactor who had a pretty serious inside track. I'll have to check it out. Thanks for the heads-up; if you're correct, there's another serious re-write in my future.
 
  • #22
Bob S said:
I read a long time ago that xenon gas was deadly poisonous, at least that is what the San Francisco Chronical science editor wrote, after he toured the Lawrence Livermore Lab nuclear reactor during an open house a while back.
(see http://en.wikipedia.org/wiki/Nuclear_poison)
The SFC science editor's comment is misleading.

Xe is a noble gas and chemically inert (more so than nitrogen) under normal conditions. It has five stable (non-radioactive) isotopes: Xe-128, 129, 130, 131, 132 and two extremely long-lived radioisotopes: Xe-134 and 136 with half-lives of >5.8E+22 yrs and >2.4E+21 yrs, respectively, i.e. they are effectively stable for radiological considerations. The Xe gas that one would purchase from a chemical supply company is NON-radioactive.

There are three radioisotopes: Xe-133, Xe-135 and Xe-138, which are common in fission of U-235 and Pu-239, as fission products or due to decay of I-133, I-135, I-138 respectively. Less common, or less important are Xe-137 and Xe-139, which are also radioactive. They and other radionuclides of the fission reations are intentionally retained in the fuel elements where they are produced.

One can suffocate in an inert gas since it displaces oxygen, i.e. one suffocates from lack (absence) of oxygen, not the toxicity of an inert gas. One could suffocate from breathing nothing but He, Ne, Ar, or Kr, which are also inert but not radioactive. Radon is a radioactive noble gas, which comes from the decay of heavier elements.

Xe-135 is a significant neutron poison - i.e. it has a high absorption cross-section for thermal neutrons, and as such, it is a parasitic absorber (interferes with the chain reaction) in the fission process. However, some of the enrichment of U-235 compensates for the presence of Xe-135 which is present in saturated equilibrium in a reactor.


As for air - the body needs a certain partial pressure of oxygen to function. Mountain climbers about 8000 ft (2400 m) may need additional oxygen, especially if they are exerting themselves. Edmund Hillary and Sherpa mountaineer Tenzing Norgay became the first climbers known to have reached the summit of Mount Everest on 29 May 1953. I seem to remember he did it without oxygen, and if that is the case, it is because Hillary's body had acclimated to high altitude, i.e. the hemoglobin in the blood is well above the level of someone who lives as sea level.

The lack of oxygen and reduced pressure at high altitude, and dehydration, can cause pulmonary and/or cerebral oedema, which can be fatal without prompt treatment.
http://en.wikipedia.org/wiki/Cerebral_oedema
http://en.wikipedia.org/wiki/Altitude_sickness (High altitude cerebral oedema)

Another effect of rapid decompression is 'caisson's disease or the bends', in which nitrogen in the blood comes out of solution and forms bubbles (emboli) which can be fatal in the brain or heart. It is certainly painful in the joints, and it can paralyze limbs if blood flow is restricted and nerves and muscles are deprived of oxgyen.

Pressurization of cockpits at high altitude, as well as breathing an inert He, Ne, Ar, Kr, Xe mixed with oxygen is used to prevent the bends.
 
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  • #23
I read someplace, I think the sci.physics newsgroup, that because the temperature of the ocean is above the critical temperature for oxygen, if oxygen were pumped to below 23,100 feet in the ocean it would be denser than seawater yet still gaseous. Bubbles of oxygen could be deposited on the seafloor provided it was below that depth and the oxygen would stay there, well at least until it dissolved into the water.
 
  • #24
From Bob S
I read a long time ago that xenon gas was deadly poisonous, at least that is what the San Francisco Chronical science editor wrote, after he toured the Lawrence Livermore Lab nuclear reactor during an open house a while back.
(see http://en.wikipedia.org/wiki/Nuclear_poison)
Danger said:
I'll have to look into that. The guy who told me about it was a US government subcontactor who had a pretty serious inside track. I'll have to check it out. Thanks for the heads-up; if you're correct, there's another serious re-write in my future.
Xenon gas is a product of nuclear fission, and has an extremely high cross section for absorbing thermal neutrons, and will quench or "poison" the reactivity in a nuclear reactor. The SF Chronical science reporter misunderstood the physicist's comment about xenon poisoning the reactor.

[Added text from}
http://www.statemaster.com/encyclopedia/Nuclear-reactor-physics
Short-lived poisons and controllability
Short-lived reactor poisons in fission products strongly affect how nuclear reactors can operate. Unstable fission product nuclei transmute into many different elements (secondary fission products) as they undergo a decay chain to a stable isotope. The most important such element is Xenon, because the isotope 135Xe, a secondary fission product with a half-life of about 9 hours, is an extremely strong neutron absorber. In an operating reactor, each nucleus of 135Xe is destroyed by neutron capture almost as soon as it is created, so that there is no buildup in the core. However, when a reactor shuts down, the level of 135Xe builds up in the core for about 9 hours before beginning to decay. The result is that, about 6-8 hours after a reactor is shut down, it can become physically impossible to restart the chain reaction until the 135Xe has had a chance to decay over the next several hours.
 
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  • #25
maverick_starstrider said:
I know that liquid breathing exist but the image of a rat being placed in the stuff and slowly looking like it is dying and then it starts breathing is from the movie The Abyss.
That bit was cut in the UK - can't be cruel to animals.

First movie with CGI btw.
Not by a long way, TRON was earlier (82) and the first CGI character is reckoned to be the knight in Young Sherlock (85)
 
  • #26
The way that I got it from my friend is that the xenon is used in place of helium in an oxygen mix. Since the specific gravity of xenon is very close to that of human tissue, the overall effect of having a pilot breathe the mix for a half hour or so before a flight, having his/her onboard supply of the same mix, and then flooding the cockpit with xenon is somewhat similar to packing a hard-boiled egg in a styrofoam enclosure. There's no way for things to flop around. (That explanation, incidentally, is under my pre-existing copyrite for my book. :wink:)
 
  • #27
Danger said:
Let me fix it first. :wink:
No. :frown: That is a task that has no end.
 
  • #28
Xenon is actually an anesthetic. Historically, it was used between ethers and freons. (It is believed to work because of it's physical properties - it's fat soluble and interrupts the transmission of signals between neurons) So it can be quite dangerous in concentration, because (as has been said before) it displaces oxygen - you could get in trouble and have no way to get out.
 
  • #29
i hope I am not too late but oxygen becomes toxic when the air's density consists of somewhere over 60% of O2. if i remember right.
 
  • #30
fawk3s said:
i hope I am not too late but oxygen becomes toxic when the air's density consists of somewhere over 60% of O2. if i remember right.

It doesn't quite work like that, the danger comes from the partial pressure - essentially the amount of oxygen present.

At one atmosphere the partial pressure is just the concentration, 100% oxygen at 1atm = 1ppa O2 is considered an irritant and you should limit it to 24hours. 50% concentration at 2 atmospheres would have the same effect.

The safety limits depend on what you are doing and for how long. For scuba diving, where a fit or blackout could cause you to drown, the limit is 1.6atm - so either pure oxygen at 1.6 atmosphere or air (20% oxygen) at 8 atmospheres. In a chamber being treated for decompression a fit/blackout isn't as dangerous so you could go to nearly twice this pressure for a short time.

Partial pressures O2 above 3-4atm are generally bad.
 
  • #31
so on low pressures you can breath 100% oxygen without any damage?
then how much do airplanes use in their tanks, you know, those for the passengers in case of an accident?
 
  • #32
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  • #33
fawk3s said:
so on low pressures you can breath 100% oxygen without any damage? then how much do airplanes use in their tanks, you know, those for the passengers in case of an accident?

You can breath pure oxygen at 0.21 atmospheres and receive the same oxygen as normal air. This is what the Mercury and Gemini spacecraft used.
This has the big advantage that in space the pressure on the hull is only 0.2atm (3psi instead of 15psi) it also saves weight and removes the risk of decompression sickness if you have to escape at altitude. 0.2 atm of pure O2 is not a fire risk.

The fire on Apollo 1 was caused by an amazingly dumb mistake in a test. The craft was designed to operate at 0.2atm pure oxygen in space, to test the doors on the ground they needed the inside to be 0.2atm higher pressure than outside. They did this by filling it with 1.2atm of pure oxygen which is an incredible fire risk - rather than keeping 0.2 atm of oxygen and adding 1atm of nitrogen/helium/or just about anything else.

Large commercial aircraft carry 100% oxygen but their cabin operates at around 0.75atm air pressure. Smaller aircraft often use 80% oxygen cylinders because with 100% O2 you have to be very careful about the type of grease, rubber, plastic etc used - 80% O2 is much safer.
 
  • #34
mgb_phys said:
The fire on Apollo 1 was caused by an amazingly dumb mistake in a test. The craft was designed to operate at 0.2atm pure oxygen in space, to test the doors on the ground they needed the inside to be 0.2atm higher pressure than outside. They did this by filling it with 1.2atm of pure oxygen...
Yes. I never knew this until I read that Wiki article just now. The story I've always known was a simplification of the facts - no mention that it was a test, and no mention that they overpressured it.
 
  • #35
Danger said:
Let me fix it first. :wink:

Since your PM box is full, I cannot be discreet and am forced publicly bug you to send me your novel.
 
<h2>1. What is the maximum air pressure that the human body can withstand?</h2><p>The maximum air pressure that the human body can withstand is around 14.7 pounds per square inch (psi), which is equivalent to the air pressure at sea level. This is because our bodies are adapted to the air pressure at sea level and any significant increase can cause serious health issues.</p><h2>2. Can a human survive in low air pressure environments?</h2><p>Yes, a human can survive in low air pressure environments for a short period of time. For example, astronauts can survive in the low air pressure environment of space for a limited time with the help of a spacesuit and oxygen supply. However, prolonged exposure to low air pressure can lead to serious health problems such as decompression sickness.</p><h2>3. What happens to the body in high air pressure environments?</h2><p>In high air pressure environments, the body experiences an increase in external pressure. This can cause the body's tissues to compress, which can lead to discomfort and pain. In extreme cases, it can also lead to tissue damage and even death.</p><h2>4. Is there a limit to how much air pressure the human body can handle?</h2><p>Yes, there is a limit to how much air pressure the human body can handle. As mentioned earlier, the maximum air pressure that the body can withstand is around 14.7 psi. Any significant increase in air pressure can cause serious health issues and can be fatal.</p><h2>5. How does air pressure affect the body during scuba diving?</h2><p>During scuba diving, the body is exposed to increasing air pressure as the diver descends deeper into the water. This can cause the air spaces in the body, such as the lungs and ears, to compress. To prevent any damage, divers need to equalize the pressure in their body by clearing their ears and using specialized equipment, such as a regulator, to breathe compressed air.</p>

1. What is the maximum air pressure that the human body can withstand?

The maximum air pressure that the human body can withstand is around 14.7 pounds per square inch (psi), which is equivalent to the air pressure at sea level. This is because our bodies are adapted to the air pressure at sea level and any significant increase can cause serious health issues.

2. Can a human survive in low air pressure environments?

Yes, a human can survive in low air pressure environments for a short period of time. For example, astronauts can survive in the low air pressure environment of space for a limited time with the help of a spacesuit and oxygen supply. However, prolonged exposure to low air pressure can lead to serious health problems such as decompression sickness.

3. What happens to the body in high air pressure environments?

In high air pressure environments, the body experiences an increase in external pressure. This can cause the body's tissues to compress, which can lead to discomfort and pain. In extreme cases, it can also lead to tissue damage and even death.

4. Is there a limit to how much air pressure the human body can handle?

Yes, there is a limit to how much air pressure the human body can handle. As mentioned earlier, the maximum air pressure that the body can withstand is around 14.7 psi. Any significant increase in air pressure can cause serious health issues and can be fatal.

5. How does air pressure affect the body during scuba diving?

During scuba diving, the body is exposed to increasing air pressure as the diver descends deeper into the water. This can cause the air spaces in the body, such as the lungs and ears, to compress. To prevent any damage, divers need to equalize the pressure in their body by clearing their ears and using specialized equipment, such as a regulator, to breathe compressed air.

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