Characteristics and Health Risks of Particulate Matter Emission from Vehicle Exhaust Under the Plateau of Low Ambient Pressure and Oxygen Concentration

Abstract

To investigate the characteristics of motor vehicle exhaust particulate matter emissions and the hazard of heavy metals on humans under the plateau environment of low ambient pressure and low oxygen concentration, tunnel experiments and bench tests were carried out in Yunnan. The differences in the composition characteristic spectra of particulate matter were described and compared respectively, a localized emission profile of particulate matter from vehicle exhaust in the Yunnan plateau region was constructed. The study indicated the mass concentrations of PM2.5 was 251.88 ± 34.62 ug/m3 in the Caohai Tunnel; the mass concentrations of PM1, PM2.5 and PM10 were 274.94 ± 28.78, 536.75 ± 97.29 and 1,126.75 ± 216.38 ug/m3 in the Xidu Tunnel, respectively; the range of PM2.5 mass concentrations which discharged by gasoline and diesel vehicles were 0.7-4.3 and 1.14-12.94 mg/m3 in the bench test. The concentrations of OC and heavy metals in plateau tunnels were higher than in plain, probably due to insufficient oxygen content in plateau region and insufficient fuel combustion under engine load. Then, Cu, Zn, Pb and Cd were significantly affected by motor vehicles, the values of non-carcinogenic risk were less than 1 for both tunnels during the test period, however, most of them were affected by Mn, Cr from both tunnels had the highest respiratory carcinogenic risk for all populations and it should receive more attention.

Keywords: Atmospheric particulate matter, Yunnan plateau, Vehicle exhaust, Composition characteristic spectra, Health risk assessment