How the global health burden changes due to heatwaves and air pollution in a warmer world

The global premature mortality attributable to air pollution and heatwaves is substantial, yet determining which driver exerts a larger impact remains a complex task. Here, mortalities associated with heatwaves, fine particulate matter (PM_2.5), and ozone (O₃) are estimated from storylines of air pollution with constant anthropogenic emissions, comparing a factual scenario for 2018-2019 to two warmer scenarios at +2K and +2.75K above pre-industrial levels. The mortality evaluation reveals regional disparities: in Asia and Africa, air pollution far outweighs heatwaves. Conversely, in Europe, heatwave effects dominate. In warmer worlds, heatwaves control changes in aggregated mortality but are partially offset by improved air quality, especially in a +2.75K scenario. The shape of the air quality indices-population-exposure curve reveals the industrialization level, indicating the degree of population exposure risk. These findings highlight the need for region-specific adaptation strategies that address both air pollution and climate change exposures to effectively reduce the global mortality burden.