The simulated results show that the PM10 distribution patterns of the 6 winter cases are similar and the PM10 dispersion patterns of the 5 rainy season episodes are also similar. Therefore, some representative simulated cases were used to study typical PM10 distributions in each season. Pollutants are dispersed by atmospheric motions. During winter, Saraburi is influenced by the northeast monsoon and prevailing wind is northeasterly wind. Whereas, prevailing winds are southwesterly and southerly winds in rainy season under the influence of the southwest monsoon. Wind speed and wind direction during the PM10 episodes can be observed from wind roses as shown in