it's the average over the entire planet, so taking that into account, people have the choice not to smoke (and very few do anymore) while people don't really have a choice when it comes to air pollution-- it affects minority communities even more because thats where the polluting factories and diesel trucks usually are.
I saw an estimate for Oakland that stated that air pollution has shortened life expectancy there by 8 years, 2.5 years was the planetary average-- so it's much worse in some communities than it is in others.