I used to play regularly at a place in Matlock Bath during a time period either side of the smoking ban. About a year before, and then about a year afterwards. Within a month of the ban the function room at the pub changed from the good old ciggy smell to a vile mixture of urine, sweat and mouldy curtains and carpets. An egg-head doctor friend of mine told me that cigarette smoke actually has an antiseptic effect and that the mould spores (now rampant) might be more harmful than the smoke! We packed the gig in soon after (not because of the smell!) so I can't confirm that.
We've all got to die of something, so I reckon we just have to make our own informed choices.