This calculation does not make sense to me. Besides assuming purely linear relations between cigarettes sales and population deaths, as well as between PM2.5 particles and population deaths, it also seems to imply the absurd assumption that every member of the population smokes the same amount of cigarettes. If they would take into account that only a quarter of the population they used smokes at all (seems about right), their resulting number of 36 would become 8 instead (and this does not even take into account that not all smokers smoke the same amount). Either I missed something, or this is just a completely meaningless calculation covered up by a smart-looking explanation.

This claim lacks citation or calculation. If, as is more often assumed, microparticles (PM2.5) are the main culprit in air pollution, the claim sounds hugely exaggerated. Even with beyond-index pollution records of almost \(1mg/m^3\) in Beijing (see e.g. Wikipedia), total microparticle (PM2.5) intake would be: $$15,000 liter/day * 1mg/1000liter = 15mg/day$$ This would be a bit more than one cigarette per day, not 30.

See this post or this Q/A for more elaborate discussions on this question.

For example Granel in Barcelona appeared around 2011 and seems to have the same concept. Besides, a century ago there may have been plenty too.