To solve traffic congestion in Bangkok, the Bangkok Mass
Transit system (BTS) constructed an overhead rail system with 24
stations. The BTS train station, S2, in this study area covers
Silom road and obstructs the air pollutant dispersion in a
congestion area. The 1: 200 physical model of the buildings along
Silom road with the train station, S2, was simulated in this
research to determine the air pollutant dispersion in the train
station area. A tracer gas (CO2) was emitted from a
simulated line source with emission rates of 0.383, 0.681, 1.293,
2.586, 5.177 and 10.77 mg/min to simulate actual pollutant
emission rates. The CO2 gas was sampled at 55
locations in the model. The Kriging method was used to
interpolate the data in the study area. . Emission rates were
used to make the difference between measured CO2 in
the model area and ambient CO2 large enough to be
differentiated. Regression Analysis was used to relate
analytically the mass emission rate to the CO2
concentration. The results indicate that the maximum CO
concentrations exceed the 30 ppm Bangkok standard along the
Southeast side of Silom Road at the passenger platform level.
Drivers will acquire more harmful levels of CO than pedestrians
at street level, especially near the Southwest end of the train
station. NO2 concentrations do not exceed the standard
(0.17 ppm) at street level. The highest predicted VOC is 1.05
ppm. These results may be used in the future for numerical
modeling study.
