Comparison of predicted and observed PM10 concentrations in several urban street canyons

Abstract

This paper presents an evaluation of a street canyon model (Operational Street Pollution Model) in several urban streets having different configurations. The model was performed for the prediction of particulate matter (PM10) concentrations from exhaust emissions of mobile sources in five street canyons in the city of Izmir, Turkey. Hourly concentrations of PM10 were observed at the streets and the relevant hourly meteorological parameters were measured at the roof level. The hourly street level measurements by a mobile ambient air quality monitoring station and on-site automatic traffic counts were conducted for 1 week in each street during the period of November 2007 and March 2008. The urban background concentrations were also obtained from four stationary air quality monitoring stations in the city during the measurement campaigns and they were included in the modeling studies as the contribution of background air quality. Finally, statistical analyses were carried out to evaluate the model performance by comparing the predicted and observed time series of PM10 concentrations using a correlation coefficient and an index of agreement (IA). The IA varied from 0.87 to 0.98 at the symmetric canyons and the correlation coefficient ranged from 0.68 to 0.92, indicating modeling performances ranging from acceptable to very good. The similar values were calculated between 0.74 and 0.76 for IA and between 0.34 and 0.41 for correlation coefficient at the asymmetric canyons. The best agreement between predicted and observed PM10 concentrations (IA = 0.98, R2 = 0.92) was found for Cumhuriyet Avenue in this study. These values are found as the best agreement in overall studies in literature.