Population aging reshapes the projected composition of future global PM2.5-attributable mortality

Long-term exposure to fine particulate matter (PM 2.5 ) is a major global health risk, with most attributable deaths occurring through noncommunicable disease (NCD) pathways. Existing global assessments commonly model four major NCD outcomes using Global Exposure Mortality Model (GEMM) functions: chronic obstructive pulmonary disease (COPD), lung cancer, ischemic heart disease, and stroke. Here, we compare their combined mortality with aggregate NCD mortality and define the difference as a subtraction-derived residual NCD category. We find a marked shift in the projected composition of global PM 2.5 -attributable NCD mortality by mid-century: the four GEMM-specified outcomes decline from approximately 64% of NCD-attributable deaths in 2015–2019 to 11% in 2056–2060, while the residual share increases from 36% to 89%. Population aging and changing baseline mortality contribute strongly to this shift, with PM 2.5 -attributable deaths increasing more than sevenfold from 0.36 million to 2.61 million. These findings highlight the need to integrate clean-air policies with healthy-aging strategies and to expand future health-impact assessments beyond the four conventionally projected NCD outcomes.