I've been fighting this battle for years. Having an asthma that reacts badly to cigarrette or especially, cigar smoke, as well as perfumes (otherwise, no problems)I carry fliers that can be posted in the club;"For medical reasons the artist politely requests no smoking" Anyone who becomes aggressive is shown my inhaler and I just point out that they are paying me to do my best work and they'll get my best work if the air is clean. Five years ago this was a battle..today I hardly ever have to put a poster up. Generally I just ask the organiser if a no smoking gig is possible and almost without exception the answer is "No problem".Smokers seem to have accepted that they should nip outside in the interval..they are free to smoke.I am free to sing at my best. The poster idea was given me by Artisan who also make a no smoking request..and I think that's the way to deal with it. A request on medical grounds is very difficult for the most ardent polluter to refuse!! Maybe you could try this approach Julie.