Emission of polycyclic aromatic hydrocarbons from different types of motor vehicles’ exhaust

In this study, most toxic polycyclic aromatic hydrocarbons (PAHs) in the vehicle exhaust were characterized and quantified carried on a chassis dynamometer test. The vehicle exhaust samples were collected under different driving cycles of vehicles such as acceleration, deceleration, uniform speed and idle conditions. The results show that the concentration of lower molecular weight PAHs (2–3 rings) in gaseous phase was higher than that in solid phase, while the concentration of high molecular weight PAHs (5–6 rings) was abundant in solid phase. The sum of two-ring, three-ring and four-ring PAHs accounted for ~87 % of the total gaseous PAH concentrations, while about 10 and 4 % of gaseous-phase PAHs were five rings and six rings, respectively. By comparison, the percentage of two-ring and three-ring PAHs were decreased in the solid-phase PAHs. Three-, four-, and five-ring PAHs had an absolute advantage in solid phase, which accounted for 89 and 81 % of the total PAHs in diesel and gasoline vehicle exhaust, respectively. The Benzo(a)pyrene-equivalent carcinogenic power (BaPE) value of PAHs ranged from 0.558 to 5.684 μg m−3 in vehicle exhaust, and the ratio of BaPE·BaP−1 was between 2.029 and 8.413. In other words, the PAHs contributed 102.9–741.3 % of the BaP equivalent carcinogenic toxicity except for sole BaP.