How does smoking affect longevity?

Question

Is it true that smoking decreases one’s life span by as much as 40% and what is its effect on one’s longevity?

Answer 1

Smokers aren't 40% more than lifers, that's not true. Still, it does make death from any cause more likely relative to non-smokers by that figure. Accordingly, this particular figure says that someone who has smoked at any point in the past has a chance of dying that is 40% higher than his age peer who has never smoked.