Future control pathways of PM_2.5 constituents and emission sources under different SSPs from a health perspective

PM_2.5 constituents may exhibit greater toxicity than the total mass of PM_2.5. However, the number of avoided premature deaths due to the changes in PM_2.5 constituents concentrations and the the control pathways under future different Shared Socioeconomic Pathways (SSPs) are unclear. We projected the avoided premature deaths related to different health endpoints (all-cause disease, cardiovascular disease, respiratory disease, ischemic heart disease and stroke) attributable to PM_2.5 constituents (BC, NH₄⁺, NO₃^-, OM and SO₄^2-) from 2022 to 2100 in China across different SSPs. The SSP1-2.6 scenario was expected to achieve approximately 380 thousand avoided premature deaths attributable to all PM_2.5 constituents. With age structure taken into account, the total avoided premature deaths were expected to increase by 37.5 %, 61.2 % and 80.5 % under SSP1-2.6, SSP2-4.5 and SSP5-8.5 scenarios, respectively. The total avoided premature deaths attributable to all-cause disease were expected to be mainly attributable to SO₄^2- due to a relatively large gap between SO₄^2- concentration in 2022 and the goals of SSPs as well as a higher β value, suggesting the priority of controls on residential coal combustion, power, and industrial boilers. The avoided premature deaths showed the highest sensitivity to BC and it is essential to prioritize the controls of residential coal combustion, residential biofuel combustion and off-road mobile source. Each province is advised to take targeted control measures in different seasons and for specific age groups.