It certainly depends on the dosages I'd imagine. Those people being incredibly dramatic as they walk past you on a street corner are being just that...dramatic. Someone who works a couple years in a bar, likewise, will be just fine. Now, maybe if you lived during your developing (childhood) years in a heavy smoking environment you'd have a point, or if you worked at a bar for 50 years. Frankly, even then, you have a chance and still a relatively small one. I'd wager your likelihood of heart disease in a similiar situation is probably far more significant.

It isn't that its harmless. Its that there's a large amount of manufactured hysteria with it.