Is this some kind of a seasonal thing?
It's certainly annoying enough to be walking along in the wake of one of these people. They are female as often as they are male, and you can see the evidence of their folly on their faces. I'll bet most of these people are 10 years younger than I am, and sleep twice as much per night as I do; yet they have the same bags or dark rings around their eyes, the same lines on their brows, as I have. I seldom exercise, either, save to mow the lawn every 10-14 days, and yet I'll bet I could match most of them for lung capacity, general cardiopulmonary health, and stamina.
In case somebody hasn't heard the news flash:
Smoking is bad for you. Carcinogens are just some of the many health hazards it carries.
Also, exposing other people to secondhand smoke outdoors, in an academic environment, is just antisocial. It's obnoxious at the least. If you feel such a need, clear a path for those of us who want to jog past you.
Edit, 15:50 CDT: For the record, I don't mean to say that people should not be allowed to smoke, or should feel guilty about doing so out in the open where it has a minimal effect on others. I have an opinion about the detrimental effects of cigarette smoke, but I would not impose my will in despite of anyone's sovereign rights as an individual. Rather, I'm saying: be considerate of people when they have to share your space, be it a room, a confined area, or a walkway. Furthermore, I am aware that there are many carcinogens other than those in cigarette smoke; I don't think it's hypocritical to make a public statement about what things I can affect, even minimally.