A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, School of Environment, Resources and Developmen6

Thesis (M.Sc.) - Asian Institute of Technology, 1997

A monitoring program for benzene and toluene concentrations in ambient air was conducted to evaluate the air pollution problems in Bangkok city arising from vehicle exhaust emission. Four air sampling stations were strategically established to cover the Bangkok Metropolitan Area. The ambient air samples were carried out to determine the correlation of different traffic configurations between peak hour and non peak hour, weekday and weekend, finally between day-time and night-time. The minimum and maximum concentrations of benzene and toluene in ambient air of the study areas were in the range of 12.34-35.82 æg/m3 and 17.43-93.55 æg/m 3 for 8-hour average, respectively. The highest benzene and toluene concentrations were found at Yaowaraj sampling station while the lowest benzene and toluene concentrations were found at Land Development Division sampling station. From the results, it should be noted that benzene and toluene concentrations for peak hour were unexpected to be lower than non peak hour. On the other hand, benzene and toluene concentrations for weekday and day-time were considerably higher than weekend and night time respectively. The finding also shown that there was a correlation between the average benzene and toluene concentrations with average traffic speed in each traffic zones. In general, the benzene concentrations were exceeded WHO guidelines while the toluene concentrations were well below this guidelines, in respect to all the traffic zones in Bangkok.