Spatial and temporal variations of pm<inf>2.5</inf> in the Vicinity of Expressways in Bangkok, Thailand

Abstract

© Springer Nature Switzerland AG 2020. The ambient air concentrations of PM2.5 were investigated in Bangkok’s urban and suburban expressways during the peak and off-peak period traffic congestion. The locations of the selected study areas were Leab Mae Nam (Inner Bangkok), Ram Intra (Outer Bangkok) and Jatuchot Expressways (suburban) which consisted of six sampling sites for each expressway toll. The sampling sites where located close to the expressway tolls were detected the greatest average concentrations of PM2.5 which showed the values of 44.79, 24.17 and 33.41 μg/m3 for Leab Mae Nam, Ram Intra and Jatuchot Expressways, correspondingly. Conversely, the sampling sites situated far from the expressway tolls were investigated the lowest mean levels of PM2.5 that illustrated the values of 12.72, 13.97 and 20.89 μg/m3 for Leab Mae Nam, Ram Intra and Jatuchot Expressway tolls, respectively. The distance between the expressways and sampling sites was influenced on PM2.5 concentrations, which indicated that the longer distance from the expressway tolls, the lower level of PM2.5. Moreover, statistical analysis of the PM2.5 data showed an insignificant difference among the three expressway tolls. For this reason, the results displayed a similar pattern to PM concentrations in urban and suburban expressway tolls. In terms of peak and off-peak periods, PM2.5 values of the three expressway tolls showed a significant difference. Normally, most PM2.5 derives from the combustion of gasoline and diesel fuel in vehicle engines. Therefore, the levels of PM2.5 in peak periods tended to be greater than those observed in the off-peak period.