Spatiotemporal evolution and risk thresholds of PM components in China from the human health perspective.

PM is a significant global public health hazard, with its components closely linked to various fatal diseases, thereby significantly increasing mortality rates. This study analysed the spatiotemporal evolution of PM-related mortality and death rates in China using risk attribution methods based on PM-component and population data. The study used a LightGBM model based on Bayesian and SHAP algorithms to identify the concentration thresholds at which the components of PM affect mortality. The results showed that from 2001 to 2022, the mortality rates influenced by the 5 PM components showed a consistent downward trend, decreasing by 101,000-529,000, with a mean annual decrease of 2.2-4.6 %. The relative importance of organic matter (OM), nitrate (NO) and ammonium (NH) in influencing mortality increased by 6.3, 17.4 and 4 % respectively, while the relative importance of black carbon (BC) and sulphate (SO) in influencing mortality decreased rapidly to approximately 2 %. The contribution of OM and SO to mortality exceeded 30 %, with thresholds of 8.6-10.3 and 9.6-10.5 μg/m, respectively. The thresholds for the effects of NO, NH, and BC on mortality were 6.8-9.4, 3.4-6, and 1.8-3.5 μg/m, respectively. This study provides effective insights for policymakers to help formulate targeted air pollution control measures and optimise public health interventions to support human health and sustainable societal development.