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Posted : August 20, 2008
Hi Andrew I am Nitrox I qualified and tend to use Nitrox on an air profile. I usually do 3 dives a day (during a week trip) with the third dive breathing 21% oxygen. Consequently my dive computer is set to an air profile and doesnt deliver any Oxygen Loading info.
I have recently read some more literature regarding the dangers of Pulmonary toxicity and wonder whether I should in fact be using the computer set to Nitrox in order to monitor the risk to over exposure? Is there a risk here? The NOAA tables seem to indicate that there is no risk to over exposure in this manner of diving but I just was after some reassurance. Thanks for your help. Lee


Answer
Posted : September 2, 2008
Hi Lee,

you don't indicate how rich the mixes are nor do you point out if these are deco or no-deco dives...

The loading at three dives a day will build up both CNS and Pulmonary... for a week long dive trip it is strongly recommended by virtually all training agencies - derived largely by the theoretical nature of the tables - they aren't a precise fit for everyones physiology - nor fitness, nor precise hydration levels during each and every dive... The general rule is have a day off mid week (I dive say Wednesday am, then resume diving again Thursday noon so you have had 24 hours off in a more sensible manner. This huely helps with rehydration and off-gassing.

The Gas you breathe will for each hour in water drain your body of circa 1 L of fluids through dehydration through your lungs given how dry the air/gas is...

Without posting a long answer the best advice I can give you is set your computer to nitrox, be careful with reverse profiles (I KNOW THE SCIENTISTS ETC ARE PREVARICATING OVER THIS ONE) - Check your equivalent air depths each dive in any day is not getting deeper even though you are diving to progressively shallower depths - your EADs may be physiologically diving you deeper each time, have that mid week break and hydrate well...

cheers and thanks Andrew.
ps if you want the detail - just ask - happy to help
Answer provided by ADM Diving

Andrew Dawson-Maddocks
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