Stronger actions are needed to advance PM_2.5 mitigation and its health benefits under population aging in China: Evidence from China's Clean Air Actions

Ambient fine particulate matter (PM_2.5) remains a leading contributor to the global disease burden. China's Clean Air Actions (CAAs) implemented from 2013 to 2020 achieved substantial progress in PM_2.5 mitigation. However, since the third-phase CAA was launched in 2023, nationwide evidence has remained limited on whether further PM_2.5 improvements and related health benefits can be sustained amid population aging. We generated a daily 1 km PM_2.5 dataset for Chinese Mainland for 2015-2024 to evaluate changes in PM_2.5 pollution, exceedances of the WHO Air Quality Guidelines (AQGs), and population-weighted exposure. Health benefits were assessed by estimating PM_2.5-attributable cardiovascular disease (CVD) mortality, while decomposition analysis quantified the offsetting effect of population aging. National PM_2.5 concentration declined from 35.57 in 2015 to 20.62 μg/m³ in 2024, with a rebound occurring in 2023. Population-weighted PM_2.5 decreased by 37.35%. The proportion of the area exceeding the WHO first interim target (35 μg/m³) declined from 51.07% to 1.49%. More than 99% of the population still lived in areas exceeding the WHO AQG level (5 μg/m³). PM_2.5-attributable CVD deaths declined from 2.16 (1.64-2.58) million in 2015 to 1.55 (1.14-1.91) million in 2022, before rebounding to 1.76 (1.30-2.15) million in 2024. The share of health benefits offset by population aging rose from around 40% before 2020 to 56.54% in 2024, exceeding 70% in some subregions. Although the third-phase CAA curbed the rebound in 2023, sustained efforts are still required to further reduce PM_2.5. Rapid population aging highlights the need for future policies to shift from a concentration-oriented framework toward a health-oriented framework to ensure sustained health benefits.