But much of the risk can be avoided if smoking is stopped, preferably well before age 35 Research: The impact of smoking on mortality and life expectancy in Japan Smoking reduces life expectancy by ten years in Japan, but much of the risk can be avoided by giving up smoking, a paper published on bmj.com today shows. Previous studies in Japan suggested smoking reduced life … [Read more...] about Smoking takes 10 years off life expectancy in Japan, not 4 as previously thought, experts warn