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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

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
The views expressed by the author are their own and the publishers accept no liability for the advice and views expressed by the author, or other users, which are provided as a general service to divers. Users are warned that secondary posts are the views of other users and may not be technically correct.
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