Air Pollution and Traffic Measurements in Bangkok Streets

Ambient air quality and traffic density measurements were conducted during January to December 2001 at four air monitoring sites in Bangkok Metropolitan Region (BMR). The ambient air pollutants included carbon monoxide (CO), particulate matter (PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3) and benzene. The diurnal variations of air pollutant levels were generally identical to the corresponding traffic volume patterns during rush/non rush hours and day/night times. Average air pollutant concentration during weekday was found to be higher than during weekend. The air pollutant concentration was related to the traffic flow pattern and human activities. The test result showed vide variations between air pollutant concentrations and with traffic characteristic, street geometries Shing Tet Leong, S. Muttamara and P. Laortanakul 186 Asian J. Energy Environ., Vol. 3, Issues 3-4, (2002), pp. 185-213 and meteorological parameters. Most of the air pollutant concentrations showed indicative correlation with traffic density. However, there was a relatively smaller correlation between average hourly concentrations of sulfur dioxide and ozone and traffic densities. The finding shows that the average air pollutant concentrations for the three urban sites are noticeably higher than the suburban site. Similarly, the traffic speeds were very well correlated with traffic densities. Lower traffic speeds were observed among station with slow moving traffic (high traffic density) while higher traffic speeds were found among station with fast traffic movement. Our analysis revealed that an obvious way to reduce the build-up of pollutant concentration on Bangkok streets would be to speed up the flow of traffic and prevent long periods of idling in congested streets.