question, of breathing pure nitrogen

Dr.wo said:

question, of breathing pure nitrogen at elevated altitudes.

Breathing pure nitrogen is incompatible with life, and will produce death from anoxia after a
few minutes.

Quoted message said:

I'm curious about the amount of reduction in time of useful conciousnes that may be caused by
breathing nitrogen instead of air in an aircraft cabin that has depressurized at about 30,000
ft. msl.

Consciousness is lost within 15 seconds or so.

Quoted message said:

The human factors charts which I have been able to access say that breathing air will produce
about 58 seconds of useful conciousness at 30,000 and 20something seconds at 40,000.

I don't have exact figures, but that sounds plausible. There are a couple of variables to consider.

Breathing pure oxygen can extend the period of consciousness; at lower altitudes one may remain
conscious indefinitely with pure oxygen. At higher altitudes, even pure O2 isn't sufficient unless
it is under pressure.

However, in all cases, breathing pure nitrogen causes death.

--
Transpose hotmail and mxsmanic in my e-mail address to reach me directly.

At first sight this is a dumb question but upon some reflection it looks more interesting. Because,
breathing takes in oxygen *and* clears carbon dioxide. (Among other functions.)

Breathing pure nitrogen stops the oxygen intake, leading shortly to consciousness loss and death.
This seems likely to happen more quickly breathing nitrogen than holding your breath, because when
you hold your breath, you have a small oxygen reservoir in your lungs.

The interesting detail comes with thinking about the carbon dioxide. If you are breathing nitrogen
you will be clearing carbon dioxide just fine. Might this contribute to useful consciousness lasting
slightly longer?

So if someone out there can speak from experimental test results, I'd like that answer better than
what I see in this thread so far.

Cheers -- Martha Adams

Martha H Adams said:

The interesting detail comes with thinking about the carbon dioxide. If you are breathing nitrogen
you will be clearing carbon dioxide just fine. Might this contribute to useful consciousness
lasting slightly longer?

No, but it will keep the breathing reflex at bay--that is, as long as you clear CO2, you won't feel
as if you are out of breath. You'll just quietly pass out. The urge to breathe is stimulated by high
CO2 levels, as when holding one's breath (the CO2 builds up and is not blown off by the lungs), but
if you are clearing CO2, that urge will never develop.

Quoted message said:

So if someone out there can speak from experimental test results, I'd like that answer better than
what I see in this thread so far.

Those who experiment with breathing pure nitrogen generally don't live to publish their results.

Nitrogen itself is not toxic at atmospheric pressure. Breathing nitrogen under pressure can produce
nitrogen narcosis ("rapture of the deep"😉, an intoxication similar to that of nitrous oxide.

--
Transpose hotmail and mxsmanic in my e-mail address to reach me directly.