Oxygen deficient atmospheres (Physiologists/Meds)???
Discussion
I have been debating this with friends for a while and have got no further forward with an actual answer. I place my faith in PH to enlighten me.
I explore old metal mines as a hobby and one of the hazards is low oxygen. Not particularly hydrogen sulphide or methane, just low oxygen.
I've debated this with meds, trainers and am myself a chemist/science teacher. Of course, the military have invested heavily in diving gases and everyone knows about mountaineering. Not too many people know about oxygen deficient atmospheres.
I either carry a Davy Lamp which goes out at about 15% (and it's time to leave) or a 4-gas meter.
[i]Here is what the "witch doctor of the interweb" says.
O2% by volume. Symptoms during reduction from :-
21 to 14% First perceptible signs with increased rate and volume of breathing, accelerated pulse rate and diminished ability to maintain attention.
between
14 to 10% Consciousness continues, but judgment becomes faulty. Rapid fatigue following exertion. Emotions effected, in particularly ill temper is easily aroused.
10 to 6% Can cause nausea and vomiting. Loss of ability to perform any vigorous movement or even move at all. Often the victim may not be aware that anything is wrong until collapsing and being unable to walk or crawl. Even if resuscitation is possible, there may be permanent brain damage.
below
6% Gasping breath. Convulsive movements may occur. Breathing stops, but heart may continue beating for a few minutes - ultimately death. [/i]
Interesting read:- http://wasg.iinet.net.au/Co2paper.html
People are a bit nebulous about limits, probably because of the variation between people and the exertion being done.
I'd like to know a lot more about what the safest minimum amount a person can tolerate "at rest" and why this has been arrived at.
Clearly the partial pressures are different and so it's not quite as simple as saying "well, it's got to be similar to climbing a mountain". It's slightly different as there is no CO2 present as would be if combustion had lowered the level. CO2 messes with respiration. Here it would be absent.
It's all very well having a gas meter, but it's a better idea to know what it means. It would be nice to sit down and be able to recouperate without being in too much danger. The biological oxidation of pyrite minerals can drag the oxygen level down to about 9% where there is no ventilation. Clearly this may sound bloody dangerous but we are trained and careful.
The bad air stories can be quite entertaining with people getting blue lips, pins and needles, tunnel vision, headaches, symptoms of intoxication, etc. In certain cases (usually with coal mines-which is bloody stupid) abseiling into shafts presents this hazard.
Here's a photo of one of the chaps note bad air warnings. Goes below 10% there.
So, the question is "how low can a healthy human go" if you make any assumptions, outline where.
One of our lot is considering doing some pukka medical research at some point. I'd like to get amongst the theory first though.....
Cheers, TP
I explore old metal mines as a hobby and one of the hazards is low oxygen. Not particularly hydrogen sulphide or methane, just low oxygen.
I've debated this with meds, trainers and am myself a chemist/science teacher. Of course, the military have invested heavily in diving gases and everyone knows about mountaineering. Not too many people know about oxygen deficient atmospheres.
I either carry a Davy Lamp which goes out at about 15% (and it's time to leave) or a 4-gas meter.
[i]Here is what the "witch doctor of the interweb" says.
O2% by volume. Symptoms during reduction from :-
21 to 14% First perceptible signs with increased rate and volume of breathing, accelerated pulse rate and diminished ability to maintain attention.
between
14 to 10% Consciousness continues, but judgment becomes faulty. Rapid fatigue following exertion. Emotions effected, in particularly ill temper is easily aroused.
10 to 6% Can cause nausea and vomiting. Loss of ability to perform any vigorous movement or even move at all. Often the victim may not be aware that anything is wrong until collapsing and being unable to walk or crawl. Even if resuscitation is possible, there may be permanent brain damage.
below
6% Gasping breath. Convulsive movements may occur. Breathing stops, but heart may continue beating for a few minutes - ultimately death. [/i]
Interesting read:- http://wasg.iinet.net.au/Co2paper.html
People are a bit nebulous about limits, probably because of the variation between people and the exertion being done.
I'd like to know a lot more about what the safest minimum amount a person can tolerate "at rest" and why this has been arrived at.
Clearly the partial pressures are different and so it's not quite as simple as saying "well, it's got to be similar to climbing a mountain". It's slightly different as there is no CO2 present as would be if combustion had lowered the level. CO2 messes with respiration. Here it would be absent.
It's all very well having a gas meter, but it's a better idea to know what it means. It would be nice to sit down and be able to recouperate without being in too much danger. The biological oxidation of pyrite minerals can drag the oxygen level down to about 9% where there is no ventilation. Clearly this may sound bloody dangerous but we are trained and careful.
The bad air stories can be quite entertaining with people getting blue lips, pins and needles, tunnel vision, headaches, symptoms of intoxication, etc. In certain cases (usually with coal mines-which is bloody stupid) abseiling into shafts presents this hazard.
Here's a photo of one of the chaps note bad air warnings. Goes below 10% there.
Removed by Mod
So, the question is "how low can a healthy human go" if you make any assumptions, outline where.
One of our lot is considering doing some pukka medical research at some point. I'd like to get amongst the theory first though.....
Cheers, TP
Edited by ThatPhilBrettGuy on Friday 12th February 18:01
tank slapper said:
The children at 28dayslater don't like PH for some reason, so linking to them isn't usually the best idea.
I don't post pictures myself as there are potential access/rescue consequences. It was relevant to my post (bad air). You can't just go swanning into one of these places without putting yourself in huge danger. Rotten false floors above hundreds of feet drops are possible. I'm interested in the air "truth" though.
Interesting stuff. Thanks.
Right. So the saturation of haemoglobin is directly proportional to the effective pressure of Oxygen and that's it.
Interesting stuff, makes things a lot more simple. Hypoxia and wikipedia was my friend.
I'll have to do some calculations and relate people's experiences at height (preferably with no altitude training) with %O2 at STP.
Right. So the saturation of haemoglobin is directly proportional to the effective pressure of Oxygen and that's it.
Interesting stuff, makes things a lot more simple. Hypoxia and wikipedia was my friend.
I'll have to do some calculations and relate people's experiences at height (preferably with no altitude training) with %O2 at STP.
Edited by Tangent Police on Friday 12th February 18:41
That is the plan from my Med mate. I don't like the idea of tapping an artery though 
Clearly, people respond to altitudes/low O2 differently due to fitness but there will be a level which fits all.
Reading more about hypoxia, I must have been fit at the time as when I've heard people moaning about headaches/pins and needles/tunnel vision/drunkness, I've felt fine.
I'm going to do some research and calculations and then test it. We may need bottled air for some of it, but it will go further knowing when to use it.
Clearly, people respond to altitudes/low O2 differently due to fitness but there will be a level which fits all.
Reading more about hypoxia, I must have been fit at the time as when I've heard people moaning about headaches/pins and needles/tunnel vision/drunkness, I've felt fine.
I'm going to do some research and calculations and then test it. We may need bottled air for some of it, but it will go further knowing when to use it.
Good link, I'll have a peruse.
There is some interesting work to be done here. I'm up for some collaboration/discussion/criticism with anyone who is interested in the area.
We have some good research areas as well. (which are very difficult to create artifically-this coincides with altitude research)
I've learned a lot today.
Edit:- Quite a few of my chaps are involved in underground rescue and so this research is very relevant in a field with the dogma of "If it's lower than 19.5% you can't go in". We need to be looking around the 11-12% mark and gaining proper insight into how people behave.
There is some interesting work to be done here. I'm up for some collaboration/discussion/criticism with anyone who is interested in the area.
We have some good research areas as well. (which are very difficult to create artifically-this coincides with altitude research)
I've learned a lot today.
Edit:- Quite a few of my chaps are involved in underground rescue and so this research is very relevant in a field with the dogma of "If it's lower than 19.5% you can't go in". We need to be looking around the 11-12% mark and gaining proper insight into how people behave.
Edited by Tangent Police on Saturday 13th February 02:35
The rate of onset appears to vary with the gradient of the oxygen. I'm going to do some more research/maths over the weekend and then actually trial myself in some various atmospheres. What I want to do is to get a safe lower limit. Obviously, you could go into 14% and exert yourself silly and pass out, but I would want to be able to have enough reserve to back myself right off, relax and not black out/collapse.
Unlike black damp (CO2) there is very little variation in actual height from teh floor. If you were to wander into a low air/CO2 mix and pass out, you'd probably suffocate on the floor in the CO2.
I imagine it's around the 11.5% mark (off the top of my head) to be marginal.
Since there will be a lot written about altitude sickness, all I have to do is work the maths backwards to an effective pressure of O2 and then turn that into a ratio at ground level.
I'll post my results as I get them.
The biggest danger is hitting low oxygen when abseiling in a shaft. It's all very well having a meter, but you need to be 100% certain you have a margin to get yourself out. What is more odd is that when you start an ascent in low O2 and work your way up, it feels that you are getting fitter/fresher/more able with exercise. Very odd indeed.
Unlike black damp (CO2) there is very little variation in actual height from teh floor. If you were to wander into a low air/CO2 mix and pass out, you'd probably suffocate on the floor in the CO2.
I imagine it's around the 11.5% mark (off the top of my head) to be marginal.
Since there will be a lot written about altitude sickness, all I have to do is work the maths backwards to an effective pressure of O2 and then turn that into a ratio at ground level.
I'll post my results as I get them.
The biggest danger is hitting low oxygen when abseiling in a shaft. It's all very well having a meter, but you need to be 100% certain you have a margin to get yourself out. What is more odd is that when you start an ascent in low O2 and work your way up, it feels that you are getting fitter/fresher/more able with exercise. Very odd indeed.
RRS_Staffs said:
I applaud the bravery of the OP in looking to put him/herself in severe risk environments and looking for casual back of fag packet type advice on an internet forum for protection!
This is on the back of hundreds of trips underground, talking with industry professionals, people who write risk assessments for such tasks, people with years of experience. Rescue teams, the works. Bad air isn't half the danger. Getting buried probably is!
There is a lot of dogma around confined space atmospheres and looking for actual answers brings up the usual "If your flame goes out, or your meter alarms, get out"
I've learned some interesting stuff so far.
Update, I was good for +/-14% earlier. Got a bit of a headache at one point, breathing was pretty normal, heart rate was up by a fair bit. Exertion was like I had doubled in weight. Think I had mild tunnel vision as well. No emotional effects, no drunken giddyness. Pretty fine.
My mate had trouble ascending a shaft and complained of being breathless and knackered at 15%. I took it steady and was fine.
My mate had trouble ascending a shaft and complained of being breathless and knackered at 15%. I took it steady and was fine.
Edited by tangent police on Thursday 18th March 01:04
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