concentrations declined substantially after 2014, the health burden remained substantial and shifted from rural to urban populations. Population aging was the dominant driver, especially in rural areas, where it offset much of the benefit from air-quality improvement. Urban population growth further increased risks, whereas rural depopulation and urban expansion reduced rural burdens. Declining baseline mortality prevented premature deaths but disproportionately benefited urban residents due to healthcare access inequities. These urban-rural trends were consistent across different exposure-response models, underscoring the robustness of our findings. These findings highlight the need for differentiated environmental health policies that integrate demographic changes, regional disparities, and environmental justice, coordinated urban-rural air-quality management, and targeted health interventions for aging populations.
Li et al. (2026) studied this question.