Drivers of reduction in PM_2.5 concentrations and related health risks in China from 2013 to 2023

From 2013 to 2023, China implemented three phases clean air actions, resulted in significantly reduction in ambient fine particles matter (PM_2.5) concentration. However, the phase-specific driving factors behind PM_2.5 changes and associated health benefits over this period have not been comprehensively investigated. Here, we quantify the public health burden attributable to changes in PM_2.5 concentration, using an integrated framework that combines an emission inventory model, a chemical transport model, and a health risk assessment model. We found that the national PM_2.5 concentration decreased substantially by 20.7 μg m^-3 (36.8%) during Phase Ⅰ (2013-2017), 4.3 μg m^-3 (7.6%) during Phase Ⅱ (2017-2020), and 0.7 μg m^-3 (12.1%) during Phase Ⅲ (2020-2023). These reductions led to approximately 0.46 (95% Confidence Interval: 0.40-0.51) million, 0.18 (95%CI: 0.16-0.21) million, and 0.27 (95%CI: 0.23-0.31) million avoided premature deaths, respectively. Considering the influence of driving factors for air pollution control, the contribution of anthropogenic emissions declined markedly from 18.2 μg m^-3 in Phase Ⅰ to 3.5 μg m^-3 in Phase Ⅱ and 2.0 μg m^-3 in Phase Ⅲ, respectively. In contrast, meteorological conditions shifted from reducing PM_2.5 concentration in Phases I and II (-2.5 and -0.8 μg m^-3) to increasing it in Phase III (+1.3 μg m^-3). The diminishing marginal effectiveness of air quality improvement during Phase Ⅱ and Phase Ⅲ was attributed to both the saturation of end-of-pipe control technologies and increasingly unfavorable meteorological conditions. Although PM_2.5 reduction potentials substantially diminished after 2020, the PM_2.5-related avoided deaths in Phase Ⅲ accounted for 29.8% of total cases, exceeding that of Phase Ⅱ (20.0%) and revealing a nonlinear health response. Our results underscore that health-oriented collaborative strategies for air pollution and climate mitigation are critical for achieving substantial air quality improvements in the future.