“Undisputedly smoking is injurious to health and may affect the health of smokers but there is no reason that health of passive smokers should also be injuriously affected. In any case there is no reason to compel non-smokers to be helpless victims of air pollution...Realising the gravity of the situation and considering the adverse effect of smoking on smokers and passive smokers, we direct and prohibit smoking in public places . . .”