Is nitrox worth it for deeper rec dives?

[tursiops]

See further down in the post.



I went back and read how the OTU was calculated, and let's run some numbers. Per the NOAA Manual 5th edition, over 6 days of diving you are allowed up to 420 OTU doses average per a day and a total of 2520. At PPO2 of 1.4 you get 1.63 OTU/min. So even if you spend the entire time at 1.4, you need to dive 257 minutes a day, and a total of 1,546 minutes for the 6 day period. So over 21 dives that would be 73 minutes per a dive, which means unless you are diving EAN40 at 80 feet (using the NOAA Nitrox charts ver 7) for every dive you aren't likely to come close to it.

Whole body toxicity is only really a concern for rebreather divers because of the select able PPO2 set point. They can tell their rebreather to keep the PPO2 at 1.3 for the entire dive, including shallow portions. Which allows them to build up the toxicity. While recreational OC divers only really near their PPO2 max for a small portion of the dive. I am willing to bet if I went through my computer my time above a PPO2 of 1.3 per a dive could be counted on my fingers and toes.

Are you arguing with me, agreeing with me, adding to what I said, or what?

 

[Manatee Diver]

Are you arguing with me, agreeing with me, adding to what I said, or what?

Adding to the quoted point with a numbers run from his planned dive series.

 

[tursiops]

Adding to the quoted point with a numbers run from his planned dive series.

Thanks. Useful.

 

[admikar]

That said, my ass, my conservatism.

My new favorite dive quote!!!

No conspiracy. There is just not enough data for any deciesive statements coming from CDC, FDA or scuba agencies. But there are valid reasons to suspect that indeed, breathing Nitrox should increase mutation rate and/or kill cells. So we are in the grey zone here, just like with taking antioxidant supplements.

I need to call my military pilot friends and a cousin (well, maybe not, I don't like him much) to tell them to stop breathing oxygen while fooling around clouds in their pointy fuel-into-noise-conversion machines.

 

[Alan Browne]

My new favorite dive quote!!!


I need to call my military pilot friends and a cousin (well, maybe not, I don't like him much) to tell them to stop breathing oxygen while fooling around clouds in their pointy fuel-into-noise-conversion machines.

I'm sure there are better quotes. ;-)

Note that fighter jocks are in cockpits that are partially pressurized (not to sea level) so the high % oxygen they are breathing just makes sure they get as much as they can use. (the % depends on the particular aircraft but it is mixed with outside air so not 100%). (At least in western aircraft, no idea about Russian, Chinese, etc.).

Fighter pilots have been known to suck on oxygen after a late night at the O-club too...

 

[Alan Browne]

See further down in the post.

Great ... and if I have visual acuity issues would I actually notice at the time?

Would I recover or is it permanent damage?

 

[Manatee Diver]

Great ... and if I have visual acuity issues would I actually notice at the time?

Would I recover or is it permanent damage?

You aren't diving enough for it to be a concern, and the NOAA manual seems to mention that the first symptom are lung issues like a dry persistent cough, I don't see any mentions of eye damage. But this is a question better for someone that knows diving physiology.

 

[tarponchik]

I need to call my military pilot friends and a cousin (well, maybe not, I don't like him much) to tell them to stop breathing oxygen while fooling around clouds in their pointy fuel-into-noise-conversion machines.

This subject is not studied. I was not able to find any long-term studies of military jet pilots health. Civil aviation pilots were shown to have somewhat higher rates of melanoma and prostate cancer than general population, but that's all.

 

[tursiops]

But I do believe that excessive O2 is bad for you because, unlike N2, oxygen is not chemically inert and it damages DNA and other vital molecules in our cells. Whether you buy this argument or not I do not care. We've been through endless discussions of the subject here on SB and I am well aware that my opinion is an irritant to many folks here, especially, for the "I-just-feel-good-breathing-NITROX" and "I-am-always-right-because-I-am-an-MD" types, but this is my opinion.

There is just not enough data for any deciesive statements coming from CDC, FDA or scuba agencies. But there are valid reasons to suspect that indeed, breathing Nitrox should increase mutation rate and/or kill cells. So we are in the grey zone here, just like with taking antioxidant supplements.

This subject is not studied. I was not able to find any long-term studies of military jet pilots health. Civil aviation pilots were shown to have somewhat higher rates of melanoma and prostate cancer than general population, but that's all.

It appears you are trending away from your original belief that the O2 we breath as divers damages our DNA.
This is good. Wildly unsupported suppositions are not helpful.

 

[Manatee Diver]

This subject is not studied. I was not able to find any long-term studies of military jet pilots health. Civil aviation pilots were shown to have somewhat higher rates of melanoma and prostate cancer than general population, but that's all.

It likely isn't a concern with the modern jet fighter, in the USAF the new goal for fighter pilots is 20 flight hours a month. Even at 100% oxygen at sea level, that is 1,200 OTU per a month, and the NOAA charts if you follow the suggestion of no more than 300 OTU a day, results in a maximum monthly OTU of 9,000. But that doesn't take into account PPO2, at the typical 8,000ft cabin altitude (which many military aircraft maintain up to a set altitude) that is 0.74 ATM, the OTU per a minute at 0.75 atm is 0.56, so over that same amount of flight hours they have a monthly OTU of 672 which is below even the maximum single day exposure limit.