Future intensification of co-occurrences of heat, PM2.5 and O3 extremes in China and India despite stringent air pollution controls

Heat and air pollution extremes are two leading global health stressors, both of which are particularly serious in China and India. It is well recognized that exposure to co-occurrence of heat and air pollution extremes will cause amplified health outcomes, yet century-long understanding of future co-occurrence is still lacking. On the basis of sophisticated regional coupled climate-chemistry modeling, we predict future individual and joint occurrences of heat and air pollution extremes in China and India in 2096-2100 relative to 2010-2014. We find intensified co-occurrences of heat and air pollution extremes in both China and India, despite reductions in projected emissions and improved air quality. Under the medium air pollution control of SSP245, the frequency of Tw&PM&O3 joint hazard increases by 382% in North India, and 729% in Beijing by the end of this century. Given the significant role of temperature changes in the co-occurrence and larger compounding health impacts, actions are urgently needed to reduce exposure to co-extreme events.