Seasonally varied cytotoxicity of organic components in PM2.5 from urban and industrial areas of a Chinese megacity.

The atmospheric fine particulate matters (PM_2.5) induce significant negative effects on human health, such as in the form of oxidative stress and pro-inflammatory response. Organic pollutants are important harmful and toxic compositions in PM_2.5, risks of which usually show temporal and spatial variations. To investigate the toxic effects of airborne organic pollutants on human lung epithelial cells A549, the PM_2.5 samples were collected monthly from both urban and industrial areas during a whole year in Nanjing, eastern China. After exposure to organic components extracted from these PM_2.5, the cell viability, lactate dehydrogenase content, oxidative stress index level and inflammatory factor expression level were measured. Supported by the concentrations of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes, results showed that, organic components of PM_2.5 from cold season (winter and spring) typically influenced cell membrane, cell oxidation and inflammatory damage, while the urban samples of warm season (summer and autumn) impacted cell viability more prominently. Spatially, the toxicity of samples from industrial sources was generally stronger than that from urban source, but urban samples induced much stronger damage to cell membranes than industrial one. The correlations between the PAHs, n-alkanes contents and toxicity parameters indicated that, the airborne organic components derived from motor vehicle exhaust and coal combustion were possibly the key toxic sources.