Dangerous Practice

[Dewit2it]

I found an underwater model advocating the use of pure O2 for breath hold dives. She says she can increase her hold times from 3 min on air to 6 min on O2. I hope someone stops and explains to her O2 toxicity.

THIS IS A NO NO KIDDIES! DO NOT TRY THIS EVER!

[Mr. X]

Interesting. I remember when I my dear old pa was in hospital & I mentioned to the nurse that the oxygen mask seemed to be providing some relief for him -- she promptly went and removed it! It seemed cruel at the time, & it might have been wiser for her to have explained her actions; fortunately I wasn't packing heat.

[trux]

Originally Posted by Dewit2it

I found an underwater model advocating the use of pure O2 for breath hold dives. She says she can increase her hold times from 3 min on air to 6 min on O2. I hope someone stops and explains to her O2 toxicity.

Well, it depends in what depth she makes the modeling. Such shots are usually made in just few meters of water, so the risk of serious poisoning may be negligible unless it takes many dives and long time underwater in total. A more serious risk than oxygen poisoning in this case is rather CO2 acidosis - by prolonging the breath-holds she produces more CO2. But seeing she makes no extreme long dives, and assuming she ventilates between the dives long enough, the risk is probably also manageable.

So, I'd tell that breathing pure oxygen is certainly not without risks, but in this very case it may be justifiable. She should just avoid doing it too often or for too long time (and of course too deep too) - pure oxygen and especially the free radicals it brings with, are rather aggressive to the organism. Besides the toxicity, it also damages tissue, and accelerates aging. I bet that if you mention it to her, as a model depending on her look, she will be certainly much more scared by the aging than the poisoning

[manhattanguy]

I don’t think that by breathing pure O2 above or on surface will expose you to the risk of any oxygen poisoning. However, there are some risks (including poisoning) involved in diving with pure O2.

I am a member of a combat diving unit (military) and we use the old closed Dräger Lar system. Every year we intensively dive for about two months to maintain our skills in under-water navigation, diving etc. During those two months I log about 350-400 hours of time under water with pure O2 (2 hours morning, 2 afternoon and 2-3 night). Our depth is dependent on water visibility but we try to stay at about 6 meters depth. We do however go deeper if needed but not deeper then about 12 meters. It’s pretty impossible to maintain a depth above 3-4 meters since you run the risk of “popping” up to the surface, that’s because we cannot empty our rebreathers in any other way then by actually breathing up the oxygen in it.

Safety wise, we all go through the “poisoning test” which is to equip the O2 gear, oxygenize the entire body by running 3km and then pressurize in a chamber to 15 meters for 15 minutes. During the years we have not got any O2 poisoning cases. Not even when my buddy’s suit got filled with water and he disappeared down to 24 meters pulling me with him to about 20 before he activated his jacket. We do get a few CO2 pass-outs due to the filter substance being clogged up by water therefore not filtering properly. TRUX is completely right in that pure O2 accelerates aging, and can destroy tissue (I am 35 but look like 50…lol..) but on top of that it completely destroys your physical fitness (your body gets used to pure O2) and that’s why we only do it for 2 months/year. After that you can barley walk up the stairs without frequent breaks.

[Mr. X]

Originally Posted by manhattanguy

... TRUX is completely right in that pure O2 accelerates aging, and can destroy tissue (I am 35 but look like 50…lol..) but on top of that it completely destroys your physical fitness (your body gets used to pure O2) and that’s why we only do it for 2 months/year. After that you can barely walk up the stairs without frequent breaks.

...And I'm sure an underwater model wouldn't be at all concerned about aging prematurely. [Good post BTW]

[Kimmo]

She says she can increase her hold times from 3 min on air to 6 min on O2

You can warn her CO2 toxicity if you want to because CO2 is the real problem while hold ones breath long enough with pure O2.

After that you can barley walk up the stairs without frequent breaks.

That is pretty interesting if I compare that personal opinion for normobaric oxygen paradox (NOP). So if it is so then dosis counts.

- kimmo

[manhattanguy]

Originally Posted by Kimmo

That is pretty interesting if I compare that personal opinion for normobaric oxygen paradox (NOP). So if it is so then dosis counts.

- kimmo

Don’t know really. None of us are scientists. I had to google the “normobaric oxygen paradox” just to have a clue…lol..

One thing I do know today is why ones admittance to the unit increases dramatically if one has NO prior scuba experience or technical knowledge in the subject. The good part is that you get removed at the age of 35 and can therefore enjoy free-diving the rest of your life (in a 50 year old body that is)