Who DOESN'T analyze their gas?

[tursiops]

I don't know how credible this is, but it says available oxygen in the air in Denver is 18%.

http://www.faqs.org/sports-science/Mo-Pl/Oxygen.html

It's wrong. PfcAJ is exactly right. The percentage is 20.9, it is only the PPO2 that has dropped to .18 at altitude (which you can call 18% of sea level pressure...but your are not at sea level). But what is causing the problem for the athletes is that each breath has fewer oxygen molecules in it, compared to how many at sea level. So they are breathing a gas that is 20.9% O2, but that gas has fewer O2 molecules than the athlete is used to in a breath...in fact 18/20.9 as much, so the athlete feels O2 starved...as if the percentage of O2 were lower. Turns out we function on PPO2, not percentage O2.....

[MichaelAngelo]

Last time I played in Denver both my o2 analyzer and computers read 18 percent o2. In reality it's .18 ATA ppo. The stage at the PAC keeps full k bottles of aviator grade o2 on both stage left and right for cast and crew. I was there 8 weeks and never fully acclimated.

[WEPIV]

I remember when I was in Colorado City working on a film years ago I had to get the carb on my old Land Rover adjusted due to some of the off-roading in higher elevations.
One time it stalled out on Mosquito Pass near Leadville and that was a bit concerning due to the multiple thousand feet drop near my driver's side tires.

[rjack]

I often don't if I'm present while the tanks are being filled and I can see the in-line analyzer. But, Tri-mix I always analyze, I don't have a CO analyzer.
I find it comical when I see people mark their tanks to the .1 percent of O2, you don't think our recreational analyzers are that accurate do you?

Labels written to the 0.X percent mean that's what it was actually analyzed at. A label of say "18/45" just says that's what's supposed to be in there. Some of us have 3-6 sets of doubles and its helpful to know what's in what even if its not yet verified for diving.

[kwinter]

It's wrong. PfcAJ is exactly right. The percentage is 20.9, it is only the PPO2 that has dropped to .18 at altitude (which you can call 18% of sea level pressure...but your are not at sea level). But what is causing the problem for the athletes is that each breath has fewer oxygen molecules in it, compared to how many at sea level. So they are breathing a gas that is 20.9% O2, but that gas has fewer O2 molecules than the athlete is used to in a breath...in fact 18/20.9 as much, so the athlete feels O2 starved...as if the percentage of O2 were lower. Turns out we function on PPO2, not percentage O2.....

Correct. And just to take it a step further, I wonder if there are any stats about EXPIRED pO2 at altitude. At sea level we inspire pO2 of 0.21 and expire about 0.16. We metabolize about 25% of the O2 molecules we inhale. But at altitude where the pO2 is 0.18, we still need to metabolize the same number of molecules. Since there are fewer in each breath, we use a greater percentage of the ones available. Hence our expired pO2 should drop more than at sea level. I don't know what the numbers would be, but maybe expired air in Denver is about 0.11? This is probably the same logic that on SCR our loop FO2 doesn't drop that much at depth compared to at the surface.

[FW]

Sigh. Science....

I think it is more an issue of semantics than science

[a64pilot]

What I've always wondered is what happens to very active divers blood count? Specifically the red blood cell count? People acclimatize to high altitudes by their bodies increasing the amount of red blood cells, I think it can as much as double.
What happens to people that spend a lot of time in high PO2? Does their red blood cell count drop? I'm talking people that spend say four or more hours diving at least five days a week, not weekend warriors like me.

[MichaelAngelo]

I think it is more an issue of semantics than science

"Sigh" semantics

[jj1987]

What I've always wondered is what happens to very active divers blood count? Specifically the red blood cell count? People acclimatize to high altitudes by their bodies increasing the amount of red blood cells, I think it can as much as double.
What happens to people that spend a lot of time in high PO2? Does their red blood cell count drop? I'm talking people that spend say four or more hours diving at least five days a week, not weekend warriors like me.

"Doc, I need to figure out if I have cancer or I'm just overexposed to nitrox."

[a64pilot]

"Doc, I need to figure out if I have cancer or I'm just overexposed to nitrox."

I'm no Doc, and I didn't stay in any motel last night, but isn't it white cell count they look at with some forms of cancer?
Somebody has to know the answer, it's just too easy a thing to check to have not been checked?