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Pete, > Chris, > > How did you personally arrive at a plan max pPO2 of 1.4 ATA? > > Either there are data to show that diving at a pPO2 from 1.3 to 1.59 ATA > is not safe or there are not. I keep my setpoint at 1.4. Personally, I don't worry much about convulsions below a PO2 of 1.8 atm; however, I have heard of divers convulsing at 1.6, so I don't want to take any chances. Convulsions at 1.4 or lower seem to be extremely rare, and often involve other medical disorders (i.e. things that predispose a person to convulsions, such as epilepsy). I base my setpoint on my gut-feeling, and my gut-feeling has come from reading a wide variety of literature on the subject, speaking at lengths with physiologists and others who have a great deal of experience with hyperbaric PO2 conditions, and a fairly robust experience base that includes many dives with various exertion levels, both in-water and in a chamber, breathing mixtures with PO2 levels far in excess of 2.0 (as high as 7+ atm). I am comfortable that the probability of me convulsing at a PO2 of 1.4 or less is well below the probability of getting killed while driving my car to the dive site; and I am content with the decompression profiles this PO2 gives me. > If manufacturers or the dive community are not prepared to speak up then > empiric evidence will win out - the equivalent of using the public as > crash test dummies. I don't care if a few survivors/machos/foolish have > been able to avoid an O2 hit - if 1.4 and above is dangerous, people will > be injured and nitrox, diving and rebreathers will take the rap. > > Well that's my opinion. What's yours? My opinion is that 1.4 is safe for the vast majority of the diving population in the vast majority of circumstances. My opinion is that 1.8 is also safe for a somewhat less-vast majority of the diving population in a somewhat less-vast majority of circumstances; however, my opinion is that because of the unpredictable and variable incidence of convulsions, the PO2 should be kept at 1.4 or less. Aloha, Rich Richard Pyle deepreef@bi*.bi*.ha*.or* ******************************************************************* "WHATEVER happens to you when you willingly go underwater is COMPLETELY and ENTIRELY your own responsibility! If you cannot accept this responsibility, stay out of the water!" *******************************************************************
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