We can look at these charges as a group as they are interlinked.
It is widely and often claimed that “smoking is the leading cause of preventable death”. By implication, presumably, not using tobacco would mean that death could be prevented. That is patently not true of course as even we non-smokers are going to die. Death simply cannot be prevented.
What could be argued is that of all the life style choices that can be made freely by individuals, smoking may result in a reduction in expected longevity, ceteris paribus, and, if measured in terms of “years of potential life lost” (YPLL), it may be one of the “most costly”. This, however, requires many more assumptions to be made and in particular a definition of how long anyone is meant to live which is an entirely subjective construct. YPLLs are often stated with respect to a reference age, for example 75, as though we all live “normalised” lives and should all live the same length of time. Clearly we do not and while smoking is one major point of difference so will be how we eat, drink, work, play and our genetic composition. The debate about what constitutes “a healthy diet” is a case in point, as everyone eats and therefore not eating “properly” will aggregate to a much greater impact on YPLLs than smoking which is undertaken only by a minority.
This concept may sound counterintuitive because “smokers die young”. Probably the disease which most would commonly associate with smoking, and where the epidemiology suggests that the risk is most elevated for smokers relative to non-smokers, would be lung cancer. According to Cancer Research UK the average age of diagnosis with lung cancer is over 70. In 2000 there were an estimated 63,000 male “smoking-related” deaths in the UK from a total of 290,000 (22%); 42,000 were in men over the age of 70. Of the estimated 51,000 female smoking-related deaths (16% of the total), 40,000 were over the age of 70. In 2014 the average age of death of men was 75.4 years, while the average age of death from lung cancer was 73.8 years, a difference of 19 months. It is normal to assume that some 80% of lung cancer cases are associated with smoking, and there is clearly a reduction in longevity, but perhaps not to the degree which might have been expected.
This raises a number of important points. There are no illnesses which are unique to smoking. Moreover the illnesses which are normally associated with smoking are typically illnesses of old age and not of youth. “The dose makes the poison” and the likelihood of illness from smoking is closely associated with duration and frequency of smoking. While it is stated that “half of all smokers will die from smoking” this is both overstated and is consistent with saying that “half of all smokers will NOT die from smoking”. The chances of developing lung cancer as a smoker are put anywhere between eight and 40 times the risks faced by non-smokers. The chance of developing lung cancer as a non-smoker is very low and so even at a high multiple of a very small risk the absolute risk of developing lung cancer as a smoker is around one in ten.
Returning to the point of what constitutes a “premature” death there is, as with addiction, no formal definition. Defining a smoking-related death as a premature death therefore makes the assumption that smoking, and smoking alone, was responsible for death. But it is readily observable that income levels, education and even where you live are also statistically significant variables. If longevity alone is your objective in life then it is best that you are rich, well educated, eat well, drink moderately, exercise and live in a nice part of the country. Even then you may not necessarily live longer, but it may well feel like you have.
Given that the basis for determining what constitutes a “smoking related” death is itself questionable, the idea that smoking will “kill a billion people over the next century” is clearly an extrapolation of poorly based assumptions. According to WHO there are currently over a billion smokers in the world. To argue that smoking will kill a billion over the next century really amounts to saying nothing other than “people alive today are unlikely to be alive 100 years from now”. This is simply, therefore, a truism.
A derivation of this argument is that “smoking kills someone every X minutes”. Taking the figures quoted above for the UK, in 2000 that would have amounted to “a smoker died every five minutes”. And a non-smoker died every minute.