What David Leyonhjelm has said here bears further thought. The war on tobacco has instead of keeping people away from it, has driven it and the user culture almost underground.
To be controversial, smoking does not "cause" cancer. There have been millions of smokers who have come to a natural end of life without cancer either being a causal factor or even present in their body to an identifiable level.
Smoking does however predispose a person to a greater chance of developing cancers including the tongue, lips, gums, throat, sinuses, thorax, lung, oesphagus, stomach, small intestine, large intestine, rectum, anus, kidneys, bladder, urethra and (for 50% of the population) penis.
There are of course the non-cancer conditions such as chronic obstructive airways disease and chronic pulmonary disease that are very unpleasant and may be triggered by smoking.
These we know and acknowledge, but I have come across several assessments of the studies of secondary or passive smoking and there is not the hard research data to support the contention. Yes, it is very unpleasant to be downwind of a smoker when you are a non-smoker, but apart from immediate discomfort there is no evidence to support that it has caused you permanent health impairment.
Remembering when smoking in the office and workplace was common place, if it had been having as great an impact on the health of the nearby non-smokers, there would be no office workers over 60 still alive, but there are still plenty about.
As David suggests, the social justice warriors need to get down off their high horses and mix with the common people in their own grounds. There is much more to life than trying to tell everyone else how they should be leading their lives.