Association between fine particulate matter (PM₂.₅) exposure and all-cause as well as cause-specific mortality: a narrative review

Air pollution, particularly fine particulate matter (PM ₂.₅ ), has been recognized by the World Health Organization as one of the leading global health risks, and its adverse health impacts represent a major research priority in public health. Accumulating epidemiological evidence demonstrates that both long-term and short-term PM ₂.₅ exposures are significantly positively associated with all-cause mortality, cardiovascular mortality, respiratory mortality, and lung cancer mortality. Nevertheless, numerous controversies and knowledge gaps persist regarding dose–response modelling, underlying biological mechanisms, and susceptibility disparities across population subgroups defined by age, sex, and pre-existing comorbidities. Furthermore, the generalizability of findings from geographically diverse settings with varying pollution levels requires further synthesis and validation. This narrative review synthesizes up-to-date evidence linking PM ₂.₅ exposure to cause-specific mortality. We focus on characterizing dose–response curve patterns, delineating putative biological pathways including oxidative stress, inflammatory responses and endothelial dysfunction, and exploring subgroup-specific susceptibility. This work aims to reconcile inconsistencies across existing studies and generate robust evidence for targeted air-pollution mitigation strategies and clinical intervention measures.