I've noted work on correlations between air pollution and reduced life expectancy in past years; the statistical differences are usually very small in comparison to what you can do for yourself via calorie restriction and exercise, as air pollution in wealthier regions of the world is a fraction of what it was a century past. As populations became radically richer in the course of the past three centuries, the luxury of being able to pay for a better environment became possible - either directly or through investment in technologies that cause less pollution in the course of achieving their end goals. It wasn't all that long ago, for example, that there were dead rivers in the US and Western Europe. Those rivers would still be dead if not for the fact that our societies are far wealthier than those of our grandparents; to be able to be an environmentalist is very much a luxury. It requires sufficient surrounding wealth or knowledge to be able to do things a different way.
In any case, here is a recent study on air quality and life expectancy in China - a region of the world that is still largely an expanse of 20th-century styled comparative poverty, scattered with enclaves and belts of modern wealth.
Outdoor air pollution is one of the most worrying environmental threats China faces today. Comprehensive and quantitative analyses of the health consequences of air pollution in China are lacking. This study reports age- and sex-specific life expectancy and health expectancies (HEs) corresponding to different levels of air pollution based on associations between air pollution and individual risks for a host of health conditions and mortality net of individual- and community-level confounders.
The main outcome measures in this study include life expectancy estimated from mortality and HEs based on five health conditions including activity of daily living, instrumental activity of daily living, cognitive status, self-rated health, and chronic conditions. Net of the controls, exposure to outdoor air pollution corresponded to subsequent reductions of life expectancy and HEs for all five health conditions. These detrimental pollution effects were stronger for women. The gap in life expectancy between areas with good air quality and moderately heavily polluted areas was 3.78 years for women of age 65 and 0.93 years for men. The differences in HEs at age 65 were also large, ranging from 1.47 years for HE for good self-rated health in men to 5.20 years for activity of daily living disability-free HE in women.
Air quality tends to be mixed up with a range of other confounding factors, however. This requires careful work on the part of researchers to have a chance of teasing out air quality effects independently of other factors that lead people to remain in areas of poor air quality:
I would be willing to wager that the correlation has more to do with the relative wealth of these areas and those who make the economic choice to live there, as well as access to medical technology and lifestyle choices. Things are rarely as simple as a two-parameter study casts them to be.
Still, aging is damage, and there's do great doubt that very polluted air does damage people over the long term, to a degree related to the level of pollution: inflammation, increased risk of age-related disease, outright lung damage, risk of cancer, that sort of thing. But once the air becomes clean enough for effects to be subtle - meaning much less in magnitude that effects of exercise, differences in wealth, intelligence, or even state of mind - then attention should turn to other controllable factors in life.