Characteristics and Health Risks of Particulate Polycyclic Aromatic Hydrocarbons and Nitro-polycyclic Aromatic Hydrocarbons at Urban and Suburban Elementary Schools in Shanghai, China

PM2.1 was collected at urban and suburban elementary schools in Shanghai during two sampling periods in cold and warm seasons in 2007. Nine polycyclic aromatic hydrocarbons (PAHs) and ten nitro-polycyclic aromatic hydrocarbons (NPAHs) in PM2.1 were determined. During both seasons, the concentrations of PAHs and NPAHs at urban and suburban schools were not significantly different (p>0.05) and were higher in the cold period than in the warm period. According to the diagnostic ratios, PAHs and NPAHs at both schools were subject to the mixed effects of vehicle emission and coal combustion during both periods. Moreover, the results of the backward trajectory showed that PAHs and NPAHs were more susceptible to external polluted air masses in the cold period. At both urban and suburban schools, the inhalation cancer risk of PAHs and NPAHs in PM2.1 for children during elementary period was dozens of times of the acceptable risk level regulated by the U.S.EPA, highlighting the adverse impact of exposure to PAHs and NPAHs on the healthy development of children.