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On Sat, 16 Sep 1995 giii01@in*.co* wrote: > Not only have a won my bet, which I just now > cashed in on at Lucy's, but when Sankey gets home > and sees this, I will have the endless amusment of > reading his comments. > > The best part is we have already heard from the > main complainers, and I don't need to tell you > that they tipped their hands completetly, and > confirmed my exact suspicions about each one of > them. My suspicion is that you don't know who the main complainers were. I got quite a number of pieces of e-mail (since I'm a well known netcop, especially on other lists) from folks who were not going public, but just wondering how to complain. I think you should barf that sushi up right now, George - you didn't earn it. People weren't complaining because you were calling them out and calling a spade a spade and making the strokery of the institutionalized tech agencies look bad. They were complaining because you were acting like a putz. Of course, if your bet was that you could act like a putz and draw reactions, then you won it. But that was a sucker bet, as it were. Even I can do that, on any reasonable list whether or not I actually know anything about the subject. > Now, lets get back to diving. > > My question, and this is for real, is if I were a > new diver coming to this list, what would you think I > should be taught about deep diving on air, PPO2's, > etc. Let's hear from those who think I am wrong - not > about me, about the subject. I would think that you should probably be told that deep diving on air is just dumb - not tech diving. I would think that you should be taught that diving on high ppo2's is a crapshoot. The odds are in favor of the house and if you keep betting, you are gonna lose eventually. The question is, what are the odds, and what is the house rakeoff. I suspect that all this stuff is lots more like a curve than a sharp cutoff thing. Even if we said that the max PPO2 was 1.0, and everyone dove it, sooner or later someone would sieze on 1.0. Would we then cut it back to .995? Would we decide that it probably wasn't an O2 siezure? This has a lot of the flavor of the 'flying after diving' thing. 12 hours seemed to be the number for years, but a small percentage got bent at altitude. DAN gathered ancedotal evidence (some folks loosely call this compiling statistics) and decided that the incident rate was tooo high and cut it back to 24 hours. People still got bent, so they wanted to go back to 48 hours. On this one they got called. Not for any reasonable risk-benefit sort of analysis, ut because tey were trying to cut the risk to absolute zero, and that couldn't be done. I guess the safest thing would be to dive only on the first day of a one week vacation, and allow six days to offgas. Maybe only dive the second day to allow time to ongas as well. And this seems to be where we are with PPO2's. Perhaps the safest form of nitrox is the one that you get through a snorkel - and you can avoid any chance of hyperbaric injury by not diving at all - just float there on the surface and look at the pretty reef. Now would your eventual chance of melanoma (from the extra sun exposure) exceed your risk/cost of dieing/injury through hyperbaric injury? How do you value the future risk of dieing against the current risk of hyperbaric injury? How bad do you want to look at that wreck in the first place? The real problem is that we don't know the relative risk or benefit. We have anecdotal evidence that high PPO2's are beneficial (especially during decompression) and morbidity evidence that idicates that there is mortal risk associated with such activities. We also have morbidity evidence associated with the general practice of diving, and no one is proposing that we abolish diving completely. So I think that we should teach people that we don't know what the curves look like, but that we seem to be off of the flat, near zero part (here I'm guessing) at about 1.4, and seem seem to be angling up fairly sharply at about 1.6. And I think that they should be taught that these are the latest in a series of risk/benefit limits, and as we learn more, that the limits might move either way. Even if your risk is only 1 injury/1000 reps, the cumulative chance of jackpotting may be significant. But I think we have to say that we really don't know how to draw the risk curves or where any particular dive falls on them. I do think we have to say that at this point in time, saying that any particular dive is completely 'safe' or completely 'unsafe' is the worst possible misinformation that can be spread. No matter where you stand on the 1.4/1.6 PPO2 limit controversy. In the old days, engineers used to look at projects, and say, well, we can probably build this one for, oh, 42 million dollars and ten lives. They would look at past history and say, this many man days of that activity has traditionally led to those number of deaths at the rate of, say, 1 death per 4500 man days of that activity. Perhaps the Golden Gate bridge was the first major project where they decided that the engineering standards were that no one would die, and that they would spend extra money (more than the lives were considered worth) to reduce the risk to as close to zero as possible, just as if the estimate had come in as XXX million dollars and yy lead engineers rather than xxx million dollars and yy common laborers. The standard set by this major project seemed to end the valuation of activities in this manner. How many diver days/death for dives of 40' or less on air? How many diver days/death for dives of 130' or less on air? Nitrox I? How many diver days/death per death for air dives to 200'? For trimix dives to 200'? For dives with 25 minute exposures at PPO2 1.6 ATA? For dives with 25 minute exposures at PPO2 1.4ATA? What is the relative cost of a DCS hit vs. a death? No one seems to compile these statistics anymore, because they aren't politically correct. But without them, you just don't know your risk. And no smart person would roll dice for money without knowing how many sides they had, or what the rules were. But still we dive. -- Nick Simicich - njs@sc*.em*.ne* - (last choice) njs@bc*.vn*.ib*.co* http://scifi.emi.net/njs.html -- Stop by and Light Up The World!
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