Reversal of trends in global fine particulate matter air pollution.

Ambient fine particulate matter (PM 2.5 ) is the world's leading environmental health risk factor. Quantification is needed of regional contributions to changes in global PM 2.5 exposure. Here we interpret satellite-derived PM 2.5 estimates over 1998-2019 and find a reversal of previous growth in global PM 2.5 air pollution, which is quantitatively attributed to contributions from 13 regions. Global population-weighted (PW) PM 2.5 exposure, related to both pollution levels and population size, increased from 1998 (28.3 μg/m 3 ) to a peak in 2011 (38.9 μg/m 3 ) and decreased steadily afterwards (34.7 μg/m 3 in 2019). Post-2011 change was related to exposure reduction in China and slowed exposure growth in other regions (especially South Asia, the Middle East and Africa). The post-2011 exposure reduction contributes to stagnation of growth in global PM 2.5 -attributable mortality and increasing health benefits per µg/m 3 marginal reduction in exposure, implying increasing urgency and benefits of PM 2.5 mitigation with aging population and cleaner air.