nitrox or air,

[TMHeimer]

Simple answer for me. Depends on the depth and cost.

 

[DevonDiver]

Since the rate of DCS incidents is already less than .01% using air there can be only a minute reduction using Nitrox.

.... and yet there are people in chambers every day..... and a significant proportion of DCI cases are 'undeserved'...meaning that they were inside NDL, no fast ascent and no 'red light' pre-disposing factors.

btw... where did your statistic come from? It suggests that 'someone' knows how many individual dives, on what gasses, are conducted globally every year....??

A hypothetical guess... PADI (alone) issue more than a million certifications per year. On average 4 dives per certification (4m dives)... then lets consider that maybe on average those divers keep diving for 4 years, each doing an average 4 dives per year (16m dives pa).

That's a very low estimate...ignoring the other agencies and assuming a low average dives per annum. 0.1% of 16m fives is 160,000 DCI cases a year?

Nitrox allows for longer available bottom time or shorter surface intervals

On what source do you base your statement about shorter surface intervals?

"PADI EANx Instructor Manual
It’s recommended that you have a surface interval of at least an hour between enriched air dives whenever possible, especially if you exceed more than 50 percent of allowable exposure. This is believed to further reduce the likelihood of oxygen toxicity."

There is no proof of any safety factor nor reduction in fatigue other than anecdotal beliefs.

Agencies don't say that EAnx is 'safer' because the reduced risk of DCI is balanced by the risk of CNS tox.

Risk of DCI is reduced. On equal duration/depth dives, the EANx diver absorbs less nitrogen than the air diver. On equal saturation dives (i.e. to NDL limits), the EANx diver absorbs the same nitrogen as the air diver (over a longer period), but off-gasses more efficiently (reduces more nitrogen) on ascent and safety stop.

Few divers seem to consider the impact of EANx as the ascent gas. As if, somehow, <40% has zero impact, but >41% suddenly becomes recognized for it's ability to accelerate decompression.

The single oft-quoted study about Nitrox and Fatigue is quite misleading because it did not study fatigue in the way that most lay-divers discuss it. That same study did, however, state a belief that air divers had more decompression stress.

 

[redacted]

Agencies don't say that EAnx is 'safer' because the reduced risk of DCI is balanced by the risk of CNS tox.

.

How do you balance two unknowns? The agencies don't say it is safer because they have no credible proof.

In my particular case, I am sure my risk of dci was greatest when I used EAN. But that is because I opted for EAN when the planned dives would have required deco if conducted on air.

 

[lamarpaulski]

hi guys do you prefer air or nitrox, when doing a lot of diving,
do you start the week off with nitrox and then switch to air,
or stay with the same all week.
thanks sam.

Why not Nitrox if it makes sense with maximum depths ? Slight cost but some added safety for sure.

 

[redacted]

Why not Nitrox if it makes sense with maximum depths ? Slight cost but some added safety for sure.

Slight cost???

I estmate that using EAN for all dives my wife and I have done would have cost me an additional $10,000.

 

[DevonDiver]

How do you balance two unknowns? The agencies don't say it is safer because they have no credible proof.

In my particular case, I am sure my risk of dci was greatest when I used EAN. But that is because I opted for EAN when the planned dives would have required deco if conducted on air.

Interested in your thoughts:

3 divers conduct dives that all result in the same level of nitrogen saturation by the end of the bottom time. The bottom depth is 30m/100ft, the ascent rate is 9m/30ft per minute and a standard 3m safety stop is conducted...

Diver A: Bottom gas - AIR / Ascent gas - AIR
Diver B: Bottom gas - EANx32 / Ascent gas - EANx32
Diver A: Bottom gas - AIR / Ascent gas - EANx32

Which diver, if any, has the lowest nitrogen tissue super-saturation upon surfacing?

Which diver, if any, has the lowest microbubble score upon surfacing?

Lastly, do nitrogen tissue super-saturation and microbubble score play a role in diver health and well-being?

 

[MaxBottomtime]

The single oft-quoted study about Nitrox and Fatigue is quite misleading because it did not study fatigue in the way that most lay-divers discuss it. That same study did, however, state a belief that air divers had more decompression stress.

There have been three peer reviewed tests, all showing there is a placebo effect when it comes to reduced fatigue using Nitrox. The only way to know for sure would be to have a double blind test with thousands of divers over thousands of various dives. Unless someone comes along with funding for those tests they will never happen. In the meantime many divers continue to repeat their claims of feeling less tired but until there is proof I will continue to trust my own feelings. If you believe in something without evidence then more power to you.
Alert Diver | Air, Nitrox and Fatigue

 

[DevonDiver]

The only way to know for sure would be to have a double blind test with thousands of divers over thousands of various dives

Not really.

Medical science simply needs to prove the effect/s of microbubble presentation at different bubble scores on the human body.

The common theory being that post-dive fatigue is a sub-clinical DCI symptom caused by high microbubble scores. The medical science is half-way there, as it is known that microbubbles (microemboli) effect the blood-brain chemistry via the immune-response.

Microbubble score can be easily measured via doppler ultrasound on test divers. Those test divers can complete a range of dive profiles known to produce high, medium or low microbubble scores. Those scores can then be compared with the same dive profiles conducted using EANx.

 

[redacted]

Sure, using different gas on othwise identical profiles will result in different gas loads. But, suggesting that there are any quantifiable dci risk differences is the issue. Is there a difference in dci risk for a pressure group C diver and a pressure group D diver? Is there an accident risk difference when driving 29 mph vs 30mph? Are Fords safer than Buicks.

 

[DevonDiver]

Sure, using different gas on othwise identical profiles will result in different gas loads. But, suggesting that there are any quantifiable dci risk differences is the issue. Is there a difference in dci risk for a pressure group C diver and a pressure group D diver? Is there an accident risk difference when driving 29 mph vs 30mph? Are Fords safer than Buicks.

Statistical risk is one thing... hits per dive is different to hits per diver. I am sure we will see eventually that people are more or less pre-disposed to DCI, regardless of factors.

If you're the one with an undiagnosed PFO.... or the atypical immuno-response...etc etc

There is also no discussion about the safety benefit of EANx when things don't go to plan. The agency materials are full of the phrase "...properly conducted dive...". But if the dive isn't properly conducted.. doesn't being less saturated improve your odds of avoiding or decreasing DCI severity substantially?

If you're the one that just lost control of your buoyancy and is heading rapidly to the surface.... would you rather be less or more nitrogen saturated?

To use your example: Are Fords safer than Buicks? Statistically... who'd know? But if I crashed, I'd want to be within whichever vehicle had the highest crash protection rating...

Statistics are great. Based on last years vehicular accident statistics, I could argue that a Model T Ford was safer than a Hummer... LOL

The point being... some get unlucky...and some are waiting for a hit without realizing.... and less saturation plus more off-gassing via EANx use is one controllable factor that could very well save them from a train-wreck.