Comparative analysis of multiple health risks from different air pollution events.

The adverse health effects of particulate matter (PM) depend on its size, composition, and concentration, varying in pollution events, such as haze, fireworks, and dust storms. However, comprehensive comparisons of their health risks remain limited. In this study, three representative event types, haze (83 % secondary sources), firework (31 % from firework burning), and dust (50 % from dust emissions), were identified and assessed using online and offline measurements in Beijing from February to May 2019. Particles (3 nm-10 µm) were predominantly deposited in the tracheobronchial (TB) and pulmonary (PUL) regions during haze and firework events, but in the extra-thoracic (ET) and TB regions during dust events and clean days. Ultrafine particles (<100 nm) accounted for ≥ 81 % deposited particle numbers across all events. Total carcinogenic risk (TCR) exceeded the safety threshold (1.0 × 10-4) during all polluted events, reaching 7.6, 4.2, and 1.5 times the levels observed on clean days (2.3 × 10-4). Chronic risks, indicated by the hazard index (HI), rose sharply during polluted events (241, 100, and 37 for firework, dust, and haze, respectively) compared with clean periods (23). Oxidative potential (OP) of PM2.5 (0.74 ± 0.028-0.82 ± 0.23 nmol/(min·m3)) was consistently higher than on clean days (0.47 ± 0.17 nmol/(min·m3)), linked to transition metals, black carbon, and secondary organic aerosols. These results highlight the diverse health risks associated with PM pollution and emphasize the need to evaluate them using multiple indicators incorporating particle number, size, mass, and composition. Greater attention should be directed toward mitigating health risks from both natural and anthropogenic emissions.