Characterization of Oxidative Potential and Ecotoxicity of the Organic Fraction of Particulate Matter in a Coastal City in China: Implications for Human Respiratory Health

This study investigated the size distributions, oxidative potential (OP_v), and acute ecotoxicity index (TI) of atmospheric organic aerosols during haze and nonhaze periods in a coastal city in China. Results indicated higher OP_v and TI levels during haze periods, with trimodal variations: the highest OP_v peak in the 7.2–10 μm and the highest TI peak in the 0–0.49 μm. For the first time, multilayer perception analysis was applied to predict both OP_v and ecotoxicity, offering enhanced accuracy by capturing synergistic and antagonistic interactions among various chemical components. Lung deposition doses of size-resolved PM inducing OP_v and TI within the human respiratory system were estimated. Findings revealed that the largest particles (7.2–10 μm) predominantly affected the head airways, whereas particles in the 1.5–3.0 μm significantly impacted the pulmonary region. This behavior is attributed to quinones and high-molecular-weight polycyclic aromatic hydrocarbons (HMW-PAHs), which have higher deposition efficiency in the head airways and elevated concentrations in the pulmonary region, respectively. To mitigate health risks associated with these toxicants, efforts should target their size-dependent properties and lung deposition efficiency, considering various health end points. This study underscores the need for size-specific mitigation strategies to effectively address the differential impacts of PM on respiratory health.