Characteristics of gaseous pollutants near a main traffic line in Beijing and its influencing factors

Abstract

Automobile exhaust emissions are becoming increasingly serious with the drastic increase of the number of vehicles in Beijing. In order to investigate the air pollution level and characteristics in the areas near the main traffic lines in Beijing and to identify the contributions from traffic and other sources, gaseous pollutants including NOx, CO, O 3, SO 2, and meteorological parameters have been monitored at a monitoring site and a contrasting site in winter and summer in 2006. The volumes of vehicles on Beiyuan Road were recorded. The average concentrations of NO, NO 2, NOx, CO, O 3, and SO 2 at the monitoring site were 0.148 mg/m 3, 0.107 mg/m 3, 0.333 mg/m 3, 5.110 mg/m 3, 0.006 mg/m 3, and 0.157 mg/m 3, respectively during the sampling period in winter and 0.021 mg/m 3, 0.068 mg/m 3, 0.101 mg/m 3, 4.170 mg/m 3, 0.083 mg/m 3, and 0.056 mg/m 3, respectively in summer. The high concentrations of CO and O 3 reflect the influence of vehicles emission near the traffic lines evidently. The higher concentrations of CO, NO and O 3 in summer may indicate that the characteristics of traffic pollution were more pronounced in summer. Results of regression analysis showed that in winter the concentrations of SO 2 and CO were significantly positively correlated with the emission of heating boilers at night and negatively correlated with wind speed in daytime. The concentrations of NO and NOx were negatively correlated with wind speed, positively correlated with emission of heating boilers in daytime and positively correlated with traffic density at nighttime. The concentrations of NO 2 were positively correlated with the emission of heating boilers in daytime and traffic density at nighttime. In summer, the air quality at the monitoring site and the contrasting site was mainly influenced by the traffic emissions.