Black Carbon and Traffic-Related PM2.5 in Bangkok Area

Abstract

This study was to investigate level of black carbon (BC) in urban areas of Bangkok, Thailand. Hourly BC concentrations were measured at two stations (operated by PCD), i.e., Bangna station and Thonburi station (roadside) during dry season by using the aethalometer (Model AE-42). The averages of hourly BC concentrations observed were 5.1±2.9 and 4.3±1.9 µg/m3, respectively. The diurnal pattern of BC levels obtained from two stations exhibited two peaks of BC concentrations occurring in the morning (0500 to 0800 LST) and late evening (2100 to 2300 LST), which the late evening peaks were higher than the morning ones. The morning peaks of BC were evidently influenced by traffic condition, while the evening peaks were possibly related to traffic associated with meteorological effects. BC concentrations from roadside stations (Thonburi) were higher than those from Bangna station possibly due to less distance of sampling equipment from roads. There was some difference of BC concentrations observed between during weekday and weekends, particularly, at roadside station (Thonburi station). In addition, increase of diesel vehicles proportion, particularly in the nighttime, contributed to higher BC concentrations. The relationships among BC concentration, air pollutants (PM2.5), vehicle fleets and meteorological variables were found.