Changing risk factors that contribute to premature mortality from ambient air pollution between 2000 and 2015

Exposure to ambient air pollution is a major global health risk factor. Using recently updated hazard ratio functions, we estimate that the global premature mortality burden attributable to ambient PM(2.5)and O(3)exposure increased by about 30% and 17%, respectively, from 2000 to 2015. We analyzed these trends in terms of tradeoffs between changes in baseline mortality, population size, age distribution and exposure. Global population growth alone increased the mortality burden by about 29% and 42% among adults and children, respectively. On the other hand, decreasing baseline mortality during the same period lowered the burden by about 18% and 55% among adults and children, respectively. In high-income countries, aging of the population contributed to increasing premature mortality, while in low-income countries, in Central and West Africa for example, the growing youth population reduced premature mortality. Our results show that improved air quality generally does not keep up with the increasing air pollution-associated disease burden in middle- and high-income countries. We conclude that improvements in health care that reduce baseline mortality along with air pollution mitigation strategies are needed to maximize benefits, and counter the growth and aging of the global population.