Personally, I think the relative safety of diving Nitrox over diving Air is way over-blown by the dive industry, and I can't imagine a situation where "failure to provide Nitrox" could be viewed as the proximate cause of a diving accident.
Most of the potential injury modes for Nitrox are the same as they are for Air. Nitrogen saturation is still a concern with Nitrox, and you can still get bent diving Nitrox, just like you can diving Air. The most serious (and potentially life threatening) types of diving injuries (expansion injuries - AGE, Mediastinal Emphysema, etc) are also still a valid concern with Nitrox - if you hold your breath on Nitrox, you will get hurt just as badly as if you hold your breath on Air. I would guess that those circumstances are the most common cause of dive accidents by far, and all the Nitrox in the world won't make up for that. OxTox is obviously more of a concern with Nitrox, but you can tox on Air, too (just not as shallow as on Nitrox).
The primary thing that "keeps us safe" as divers is the manner in which we manage our diving. We have complete control over all the operational parameters associated with a dive - we can control how deep we go, how long we stay, how fast we ascend, whether and how long we do our safety stops, etc. And in the strictest sense, it is ultimately our own choice as to whether we go diving at all - no one forces us to do it. We can terminate a dive early if we have safety concerns about the plan or conditions, or we can even choose to "thumb the dive on the dock". None of that has anything to do with the choice of breathing gas.
In other words, there is still an NDL with Nitrox, and we still have to observe it, and we still have to make a slow controlled ascent to prevent injuries like DCS, just like we do with Air. And those aspects of our dives are totally and completely under our control, no matter "what's in the tank".
I suppose there is some theoretical or anecdotal evidence to suggest that Nitrox
might be safer, based on a "slower effective ascent rate", or breathing a higher O2 mix at your safety stop, or something similar. However, I am not aware of any research that has shown this to provide any measurable increase in diving safety (that doesn't mean there isn't any, just that I am not aware of it - would be interested to read it if there were). There is so much more potential risk associated with poor diving practices, that it hardly seems worthwhile to single out the choice of breathing gas as the primary contributing factor to a dive injury (at least at recreational depths - deep dives are a different story). It's kind of like me worrying about my very slight astigmatism, which my eye doctor doesn't even bother to correct for because I am so extremely near-sighted. The cost/benefit differential is just not big enough to justify it, and if I lose my contacts or glasses, I will be so blind from that that the astigmatism won't even matter at that point.
That's not to say that I am against Nitrox. In point of fact, I dive it every chance I get. I also advocate its use for other divers (within depth and training limits, etc), every chance I get. I honestly think that everyone should get Nitrox training as soon as they are certified. I feel this way because I believe it is a far superior choice of gas for most recreational profiles - if you want more bottom time at a given depth, or longer repetitive dives, or less decompression stress, then Nitrox is a much better choice for that than Air. But Nitrox by itself won't make me any "safer" as a diver - only
I can do that.
I do like the idea of charter operators charging more for air divers, though - I would totally be in support of that (as long is it was used to subsidize Nitrox diving for me
).
-JimG
