I have been smoking for 28yrs and i have been keeping fish for about the same time, give or take a year or two for breaks.
Things are drawn into the water through the air and through your air pump etc. they say that you should never use polishes or air freasheners etc. near your aquariums because of the chemicals being dragged in to the water and i agree with this. As for smoking, the smoke can be dragged into the water as well but to be honest i have never really thought about it. maybe there is somebody that can answer that one. just hope it does'nt start a no-smoking campain hahahahaha, i don't think i could give up now.