Emissions of polycyclic aromatic hydrocarbons in PM2.5 emitted from motor vehicles exhaust (PAHs-PM2.5-MVE) under the plateau with low oxygen content

Emissions of PAHs and their derivatives from motor vehicles exhaust are mainly due to inadequate combustion of fossil fuels, the combustion efficiency of engine is lower under the plateau with low oxygen content, which will exacerbate the emission of pollutants, especially organic substance. In order to investigate the emission of PAHsPM2.5-MVE under the plateau with low oxygen content, tunnel experiments and bench tests were conducted in a typical plateau region in Yunnan Province. The study indicated the concentrations of PAHs-PM2.5-MVE in the tunnels of Caohai and Xidu reached 548.11 +/- 307.12 and 1241.19 +/- 197.54 ng/m3, respectively. The emission factor of PAHs-PM2.5-MVE in the Caohai Tunnel was estimated to be 438.61 +/- 296.86 mu g/veh/km, and that for gasoline and diesel vehicles in bench tests were 442.83 +/- 82.57 and 4098.04 +/- 551.21 mu g/kg fuel. Meanwhile, the emission factors of carbonaceous component, CO and PAHs-PM2.5-MVE were at a high level that were higher than those in plain which due to the inadequate combustion of fuels in engine. A probabilistic risk assessment framework was integrated to quantitatively estimate the exposure risk for the population of the tunnels, the HPAHs-PM2.5-MVE had potential carcinogenic risk. The study can improve our understanding of the influence of organic substance from inadequate combustion of fuels on the environment and human.