The classic, existentialist argument concerning smoking is that the smoker, even if he/she is aware that smoking is hazardous to health, makes his/her own decision to smoke. Common knowledge, however, has allowed for the public realization that smoking, via second-hand smoke, is not only harmful to smokers, but all those in the vicinity of smokers as well. In outdoor spaces, diffusion diminishes or eliminates the ability of smoke to seep into the lungs of innocent, non-smoking civilians, but within closed environments, the effects of second-hand smoke are dramatically increased (all common knowledge).
The argument thus becomes: why are smokers given the right to make decisions for nonsmokers? This is the sensible question to ask because by smoking in enclosed, public spaces and emitting second-hand smoke, smokers are making a health decision for nonsmokers. Essentially, smokers are forcing nonsmokers to engage in non-consensual smoking.
Compared to drinking, which produces indirect and unpredictable health effects upon innocents (i.e. drunk driving accidents, bar fights), smoking produces a direct, conscious and definite effect on all living things in its environment. Further, smokers inherently strip nonsmokers of their human rights by consciously rendering nonsmokers unable to make health decisions for their own body. Thus, how is it possible for one to argue that enclosed, public establishments should be allowed to permit smoking?