If cigarette smokers commence smoking as teenagers and do not quit, then eventually about half of them will be killed by tobacco, in middle or old age. This excess burden of death falls particularly heavily upon the 45-64 year old age group. Smokers between these ages are three times more likely to die prematurely than lifelong non-smokers of the same age, and in the 65-84 age group, smokers are around twice as likely to die compared to lifelong non-smokers.
In addition, a study reported in the British Medical Journal found that:
Men who never smoke have a 78% chance of reaching 73; those who start smoking by the age of 20 and never stop have a 42% chance.