though recreational technical divers with lots of money to burn like to use it because it makes them look cool on the boat too. (hope there’s no tech divers here to get PO’d at me…)
Don’t you wind up looking cool at the expense of sounding less then cool?

I think the minimum ppO2 we can survive long term at is about 0.1 ATM (half of what we are used to), but clearly much less can be tolerated for a while. The top of Everest is something like 0.07 ATM ppO2 or a third of what we are used to.

That’s amazing.

I think the minimum ppO2 we can survive long term at is about 0.1 ATM (half of what we are used to), but clearly much less can be tolerated for a while. The top of Everest is something like 0.07 ATM ppO2 or a third of what we are used to.

Ooh. Ack. So first you have one problem, then the other. Nasty.

Apparently that’s what happened in the Apollo fire, too – the capsule reached 29 PSI before it ruptured. Because of the design of the door, rescuers couldn’t get inside until the pressure equalized. Tragic.
Yeah, I read the whole Wikipedia article. I think they copied and pasted half a book.

It doesn’t have to be sudden decompression to form bubbles. I think the answer to your question is that there is much less oxygen, and much of it is bound to hemoglobin or being used. Nitrogen isn’t used in the body, it just sits there. There probably is oxygen in the bubbles, especially in sudden decompression.

Oh, that makes sense. Maybe the O2 is either taken up by red blood cells or by antioxidants. I wonder about helium though? I understand helium is used in some dive mixtures to prevent decompression sickness? Or is that nitrogen narcosis? Sorry for all the questions, I should fire up Google before I bug people

Finally, yeah humans can deal with less. Hillary climed Everest without oxygen,

I still find that hard to believe. I mean, I know people have done it, but it doesn’t seem biologically possible. Dang!