Kevrumbo
Banned
- Messages
- 5,659
- Reaction score
- 1,366
- # of dives
- 1000 - 2499
Cousteau, Dumas (and tragically with Fargues) -they all thought the danger due to Nitrogen Narcosis in deep Air could be accommodated or "gotten used to" in building up a tolerance, rather than today's understanding of the more insidious nature of CO2 poisoning/Hypercapnia, quickly incapacitating and leading into unconsciousness, and/or hyperoxic O2 seizures.A few years back I was diving repetitively to 200 fsw to film at those depths. I took about three months of gradually deeper diving to get there and dove almost daily. I experienced relatively little narcosis while at maximum depth and could locate, frame and follow movement of critters with my camera with no problem. I never went deeper than 201 fsw because I had set that as my limit. More recently I've been noticeably narced at depths as shallow as 107 fsw which I attribute to a decreased frequency of dives and less tolerance of the nitrogen build-up.
When I worked with a few Cousteau dive crews, we rarely went below 100 fsw as bottom time was important in filming.
The point is at extreme depth, you may be generating more metabolic Carbon Dioxide due to exertion than you are physically capable of eliminating by exhalation -even just floating there neutrally buoyant at 10 ATA on deep Air (ppO2 2.1) with its increased gas density (13 g/L) ten times greater than at the surface, the work-of-breathing by itself can spiral into excess CO2 retention while also increasing the likelihood of Oxygen Toxicity Seizures.
Breathing air maximum terminal depth
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