Trends of PM2·5-attributable dementia deaths in the context of population ageing in China, 2000-60: a health impact assessment.
Air pollution was recently recognised as one of the 12 major modifiable risk factors for dementia. Although China's clean air policies have substantially reduced fine particulate matter (PM2·5) concentrations since 2013, the implications for dementia-associated mortality remain unclear in the context of an ageing population. We aimed to quantify historical trends and future trajectories of PM2·5-attributable dementia mortality in China under different clean air policy scenarios.
In this health impact assessment study, we integrated exposure data, population data, exposure-response association data, and mortality information from multiple sources, to estimate PM2·5-attributable dementia deaths in China from 2000 to 2024, and projected future burdens from 2025 to 2060 under five clean air policy scenarios with progressively increasing stringency. For each scenario, analyses were done across four stages: a pollution growth phase (2000-13), an air quality improvement phase (2013-24), a mid-term projection phase with accelerating population ageing (2024-50), and a late-term projection phase with a stabilising age structure (2050-60). We calculated contributions of key driving factors (PM2·5 exposure, age structure, population size, and baseline dementia mortality rate) in each stage.
From 2000 to 2013, PM2·5-attributable dementia deaths increased from 55 668 (95% CI 12 179-175 132) to 106 571 (24 202-329 233). From 2013 to 2024, despite substantial declines in population-weighted PM2·5 concentration, PM2·5-attributable dementia deaths dramatically increased from 106 571 (95% CI 24 202-329 233) to 171 420 (38 398-533 436), with population ageing as the dominant driver of increasing dementia deaths, contributing approximately 67 000 (95% CI 15 000-205 000) PM2·5-attributable dementia deaths, followed by population size (approximately 5000 [1000-15 000] deaths) and baseline dementia mortality (approximately 4000 [0-17 000] deaths), with reductions in PM2·5 exposure avoiding approximately 11 000 [2000-32 000] deaths during this period. Across all five environmental policy scenarios, PM2·5-attributable dementia deaths were projected to increase steadily from 2024 to 2050. By 2050, the number of PM2·5-attributable dementia deaths was estimated to range from 278 411 (95% CI 59 535-851 652) in the most stringent environmental policy scenario to 490 301 (105 698-1 484 714) in the least stringent scenario. Population ageing was the main driver of increases in PM2·5-attributable dementia deaths until 2050 in all clean air policy scenarios. From 2050 to 2060, declines in PM2·5-attributable dementia deaths are observed only under scenarios combining carbon neutrality and stringent clean air policies.
Rapid population ageing has substantially offset the dementia-related health benefits of air pollution control in China. Only under stringent air pollution controls can the benefits of reduced PM2·5 exposure meaningfully offset the effects of population ageing on PM2·5-attributable dementia deaths. Integrating ambitious environmental policies with public health strategies is essential to mitigate PM2·5-attributable dementia deaths in the context of an ageing population.
Ministry of Science and Technology of the People's Republic of China and National Natural Science Foundation of China.
In this health impact assessment study, we integrated exposure data, population data, exposure-response association data, and mortality information from multiple sources, to estimate PM2·5-attributable dementia deaths in China from 2000 to 2024, and projected future burdens from 2025 to 2060 under five clean air policy scenarios with progressively increasing stringency. For each scenario, analyses were done across four stages: a pollution growth phase (2000-13), an air quality improvement phase (2013-24), a mid-term projection phase with accelerating population ageing (2024-50), and a late-term projection phase with a stabilising age structure (2050-60). We calculated contributions of key driving factors (PM2·5 exposure, age structure, population size, and baseline dementia mortality rate) in each stage.
From 2000 to 2013, PM2·5-attributable dementia deaths increased from 55 668 (95% CI 12 179-175 132) to 106 571 (24 202-329 233). From 2013 to 2024, despite substantial declines in population-weighted PM2·5 concentration, PM2·5-attributable dementia deaths dramatically increased from 106 571 (95% CI 24 202-329 233) to 171 420 (38 398-533 436), with population ageing as the dominant driver of increasing dementia deaths, contributing approximately 67 000 (95% CI 15 000-205 000) PM2·5-attributable dementia deaths, followed by population size (approximately 5000 [1000-15 000] deaths) and baseline dementia mortality (approximately 4000 [0-17 000] deaths), with reductions in PM2·5 exposure avoiding approximately 11 000 [2000-32 000] deaths during this period. Across all five environmental policy scenarios, PM2·5-attributable dementia deaths were projected to increase steadily from 2024 to 2050. By 2050, the number of PM2·5-attributable dementia deaths was estimated to range from 278 411 (95% CI 59 535-851 652) in the most stringent environmental policy scenario to 490 301 (105 698-1 484 714) in the least stringent scenario. Population ageing was the main driver of increases in PM2·5-attributable dementia deaths until 2050 in all clean air policy scenarios. From 2050 to 2060, declines in PM2·5-attributable dementia deaths are observed only under scenarios combining carbon neutrality and stringent clean air policies.
Rapid population ageing has substantially offset the dementia-related health benefits of air pollution control in China. Only under stringent air pollution controls can the benefits of reduced PM2·5 exposure meaningfully offset the effects of population ageing on PM2·5-attributable dementia deaths. Integrating ambitious environmental policies with public health strategies is essential to mitigate PM2·5-attributable dementia deaths in the context of an ageing population.
Ministry of Science and Technology of the People's Republic of China and National Natural Science Foundation of China.