PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) and nitrated-PAHs (NPAHs) emitted by gasoline vehicles: Characterization and health risk assessment

Seventeen polycyclic aromatic hydrocarbons (PAHs) and eight nitrated PAHs (NPAHs) in PM2.5 and conventional gaseous pollutants exhausted from 54 in-use gasoline vehicles encompassing different emission standards (China 1 to China 5) were tested on the chassis and engine dynamometric test bench. With the increase of emission standards, a decrease in the emissions of PM(2.5-)bound PAHs and NPAHs was detected. The emission factors (EFs) of total PAHs and NPAHs in PM2.5 emitted by the vehicles with amileage of N100,000 kmwere greater than thatemitted by the vehicleswith drivingmileage of b100,000kmunder all the fiveemission standards. The EFs of PM2.5-bound PAHs and NPAHsemitted fromport fuel injection engineswere larger than that fromgasoline direct injection engines. The emissions of PM2.5-bound PAHs and NPAHs were less correlated with the exhaust of CO, while the hydrocarbon (HC) emissions were strongly correlated with the PM2.5-bound PAHs emissions. The emissions of NPAHs and NOx had an inverse correlation. The toxic (TEQs) of total PAHs and NPAHs in China 3, China 4 and China 5 were significantly reduced compared to China 1 and China 2, which may be related to exhaust technology improvements. Although the EFs of NPAHs were significantly lower than those of PAHs, the TEQs of NPAHs were higher, which indicates that the toxic effect of NPAHs emitted by gasoline vehicles were stronger than PAHs. (C) 2020 Elsevier B.V. All rights reserved.