My best friend works in a big reputable cancer clinique. Not long ago they had a conference on the hazards of smoking. The first part of the conference was going for hours, and a friend of my friend's, a doctor said: "Well, when are we finally having a break to go and have a sigarette!" Most of the doctors smoke there.
No joking, its an educated choice that many people are taking. Not me. I believe that smoking is connected with subconscious self-punishing.