Morbidity changes induced by future air quality and demographic structure changes

Climate change mitigation policies can enhance health by improving air quality. Previous studies have evaluated historical years lived with disability (YLDs) for cardiovascular and respiratory diseases attributable to particulate matter (PM 2.5 ). However, the impact of dementia, which can significantly affect YLDs, has not been thoroughly examined in the context of climate change mitigation. In this study, we estimated global YLDs attributable to PM 2.5 using health impact assessment models and PM 2.5 concentrations simulated by a global chemical transport model under two scenarios: with and without climate change mitigation. To address appropriately the issue of dementia, we explicitly considered future demographic patterns, particularly the aging population. YLDs are projected to increase globally by 2100 in both scenarios due to global aging, increasing from 7.1 million years in 2015 to 18 million years without mitigation and to 12.5 million years with it. Mitigation measures could reduce global YLDs by 5.33 million years, by 2100, limiting the increase from 2.5 times to 1.8 times. Although mitigation measures can reduce the health impacts attributable to PM 2.5 , the role of population aging remains critical for the future. • To summarize our overall response: we added further explanation of the health impact assessment framework in the Methods section to clarify the modeling workflow and expanded the discussion of uncertainty propagation across the modeling chain. We also added new text addressing the assumptions regarding relative risk functions, disability weights, and the spatial resolution of GEOS-Chem. In addition, we enhanced the discussion of policy implications to highlight aging-sensitive and regionally targeted mitigation and adaptation strategies. Finally, we corrected minor referencing and formatting issues to ensure consistency throughout the manuscript.