I'll say one reason why I dont want to see a smoker near me in a dive boat. A lighted cigarette and trilam material dont mix.
wearing a drysuit costing more than a 1000$, I dont wanna see some careless smoker making a hole through my precious DUI suit or my BC bladder or my wing. I've been burned on the arms several times in confined areas by smokers who have no control over their hands, I dont want them near me on a dive boat.
As someone who had a hole burned in his drysuit by an errant ember from a smoker's cigarette, let me just say that if anyone is smoking anywhere but the back of the dive boat (the "smoking area" designated and announced by the crew, also conveniently far from my drysuit), I will consider it an emergency situation and do my very best to protect those on the dive boat from indeterminate peril.
If at all possible, I'll do this in a discreet and polite manner, but if the problem persists, I'm dumping the mask bucket on the problem.
I don't know why, but tobacco smoke *really* gets to me, too. A couple second-hand breaths, or even talking to a heavy smoker (complete with strong aroma), gives me a very sharp, piercing headache that persists for some time. Getting hit by a puff of diesel fumes certainly makes me a bit queasy, but that passes much more quickly than the tobacco smoke headache. I am courteous and try to make every allowance for people suffering from poorly controlled addictions, but I dive because I enjoy it. If someone smoking is going to turn my dive trip into several hours of sharp, unpleasant pain for no reason more than they don't feel like going to the downwind side or back of the boat, they are at best inconsiderately unaware of their impact and at worst... well, I suppose they could be lazy, self-centered jerks.
It is understandable, but not acceptable, that smokers tend to discount the impact of their addiction on those around them. If they admitted the detrimental impact of their smoking on others, they must then accept that the addiction may be equally bad for themselves. Obviously, they would think, nobody but an insane masochist would voluntarily subject themselves to something unpleasant, even painful, and since they are certainly not an insane masochist, their smoking must not be unpleasant or painful to them. Therefore, anyone else who comes along and claims it to be unpleasant or painful (when they're not even getting anywhere near the amount a smoker gets) must necessarily be exaggerating the effect for no reason other than their own pious elitism.
Truth be told, smoking is much more unpleasant and painful to those healthy, non-addicted people around smokers, so the logical disconnect is even more enhanced. "It's safer for the gear" works better than "I can't take the second-hand smoke" precisely because the smoker doesn't have to admit that the smoke is a problem.
(Incidentally, chefchris, that reminds me of the classic quote attributed to Mark Twain: "Stopping smoking is easy to do; I have done it thousands of times!" It all comes down to the pedantry of the definition of "addiction", and I'm not really into linguistics, prescriptive or descriptive. If you wish, you may replace "addition" and its forms with "habit" and the respective forms. I was not writing about the clinical aspects.)