French exception

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CO2 build up is a significant factor in narcosys.
However this can be prevented with the proper breathing technique, which used to be thaught carefully in Cmas courses, when max recreational depth was 54-60 meters (depending on country).
I understand that PADI-trained divers are simply thaught to "breath normally" and to never hold their breath. This results in shallow and quick breathing, which consumes a lot of air whilst providing poor ventilation to alveoli.
Deep air divers instead were thaught to use a very slow and ample ventilation pattern, employing at least 3/4 of the total vital capacity and emptying carefully the lungs for expelling CO2. And to keep a short inspiratory pause, which maximizes gas exhange as you give more time to CO2 to be released in a phase of the respiratory cycle when lungs are expanded, providing the larger exchange surface and the larger pressure gradient.
Divers trained to this kind of breathing consume less air and are almost immune from the CO2 accumulation problem. This is also a good way of reducing narchosis.
We may be talking about the same thing. I pause prior to exhalation. After a slow inhalation, I take a short pause with an open glottis prior to my slow exhalation. I inhale again almost immediately and repeat the cycle. This breathing pattern is good for gas consumption and efficient at clearing CO2. This pattern is the opposite of normal breathing on land where the pause is prior to inhalation.
 
And I also guess that more people do deep air dives (50m or more) than they will say it in public due to the opinions of others.
 
We may be talking about the same thing. I pause prior to exhalation. After a slow inhalation, I take a short pause with an open glottis prior to my slow exhalation. I inhale again almost immediately and repeat the cycle. This breathing pattern is good for gas consumption and efficient at clearing CO2. This pattern is the opposite of normal breathing on land where the pause is prior to inhalation.
You are using the correct method.
As you have a pause with the lungs full, it is called inspiratory pause.
 
And I also guess that more people do deep air dives (50m or more) than they will say it in public due to the opinions of others.
Here in Europe divers are usually quite proud of their deep air experiences.
Italian divers, in particular, are known for exaggerating a bit their diving profiles.
Definitely not hiding!
And I have never seen any public bashing of them.
 
They obviously don't interact with American public
I've done 160+ feet several times on air, unremarkable as a dive. I've not had the need to dive deeper. After initially diving it, I have been prohibited from diving Hole in the Wall in Jupiter because I do not have AN/DP
 
one of my dive buddies from Bulgaria has a group of friends there that don't switch to trimix until 100 meters.

But the group is getting smaller as they are slowly dying. Last one was a few years ago (didn't make the media). 3 of them were diving to 70 meters, 1 of them got separated. Found him later, but he was dead. Sad as he had a wife and kid.
 
Here in Europe divers are usually quite proud of their deep air experiences.
Italian divers, in particular, are known for exaggerating a bit their diving profiles.
Definitely not hiding!
And I have never seen any public bashing of them.
That’s not how it was/is on American dive internet boards. The mere mention of using air, much less using it deep was instantly was met with bashing and epic flame wars.
It was Nitox 32, and beyond 100’ you had to use trimix….only! And they were quite vocal about it.
No air period.
I think that eased up along with solo diving.
 
DAN Annual Diving Report 2020 Edition - NCBI Bookshelf is a good start.
Unfortunately, DAN Europe does not collect the data you request; possibly too embarrassing. :D


Sorry it's in French, and the figures are a bit dated (2013), but the gist is as follows :

  • 1 serious accident for 10,000 dives.
  • 50% of serious accidents affect older divers (50+) who dive deep (50m+) without the necessary habituation to depth.
  • 70 to 90% of DCS cases occur despite desaturation models being followed.
 

Another article, still in French, slightly more recent (2017, still pre-Covid era).
The conclusion is that diving accidents overwhelmingly hit older casual divers who are out of shape.

Diving to 60m on air isn't dangerous per se, diving to 60m on air with no experience, poor physical condition and undetected age-related conditions is the real problem.

PS. Whoever created the page was drunk, it has nothing to do with fashion start-ups...
 
https://www.shearwater.com/products/swift/

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