PM 2.5 -PAHs and PM 10 -PAHs at roadside environment: levels, meteorological impact, source apportionment, and health risks

Polycyclic aromatic hydrocarbon (PAH) concentrations in PM 10 and PM 2.5 were measured at the roadside of 4 typical urban roads in Tianjin from January to August 2015. The medium flow samplers with pretreated quartz filters were used for particulate matter sampling. Eighteen PAHs were analyzed by gas chromatography-mass spectrometry. The concentrations of PM 2.5 -PAHs and PM 10 -PAHs in winter were 74.98 ng/m 3 and 94.22 ng/m 3 , followed by spring and the lowest in summer. The traffic flow is positively correlated with benzo(a)pyrene, benzo(g,h,i)perylene, and coronene. The vehicle speed and temperature are significantly positively correlated with low-ring polycyclic aromatic hydrocarbons and negatively correlated with the middle- and high-cyclic aromatic hydrocarbons. The ratio analysis of some PM 2.5 -PAHs and PM 10 -PAHs suggests that gasoline and diesel vehicles were the major sources of the studied area. Industrial emission, vehicle exhaust, and vehicle non-exhaust (tire wear, brake pad wear, and road dust) were identified as the major sources of roadside PAHs using positive matrix factorization analysis. The incremental lifetime cancer risk of ingestion and dermal contact were higher than that of inhalation, indicating that ingestion and dermal contact were the primary exposure routes for cancer. Therefore, it is necessary to take measures to strictly control the PM-PAHs pollution emitted by motor vehicles and formulate standards for PM-PAHs emitted by vehicles. Graphical abstract