If you are going to poison your lungs with tobacco, that's your problem,
But if you come to class reeking of cigarettes — it becomes a problem for ME.
a) it smells nasty — and that nastiness is magnified during the workout because of the sweat.
b) could possibly affect my health! (look up third-hand smoke)
If you are a smoker, it is going to be bad enough for your classmates smelling the toxins coming out of your body through your pores.
Shower before class and don't suck on any fags until AFTER class, please. If you live with a smoker, shower immediately before you come so we don't have to smell any second-hand smoke that sticks to you.
FWIW, I'm not terribly intolerant of smokers ... until I get in the dojang.