『Abstract
　Air pollution associated with particulate matters is a serious problem in the mineral products industrial area (MPIA) in Saraburi, central Thailand. PM10 concentrations monitored at Nah Phra Laan station located in the MPIA show that PM10 levels exhibit strong seasonal variations; the number of days in 2005 that PM10 concentrations exceeded the daily National Ambient Air Quality Standard of 120 μg/m³ were 58％, 29％, and 12％ in the winter, rainy, and summer seasons, respectively. In this paper, the Hybrid Particle And Concentration Transport (HYPACT) model with meteorological fields from the Regional Atmospheric Modeling System (RAMS) was applied to Saraburi to investigate the impacts of meteorological parameters upon seasonal variations in PM10 concentration. Analysis of model results shows that daily average PM10 concentrations exceeding 200 μg/m³ are found in the downwind direction of emission sources and their horizontal gradients are strong. Hourly PM10 concentrations exhibit obvious diurnal variation with maximum values in wintertime at around 2000-2100 local standard time in association with low ventilation with light wind speed and weak vertical mixing, while in the rainy season, they are generally higher in the daytime than in the nighttime, as that mixing height in cloudy days is low in daytime whereas emission rates are high during working time.

Keywords: PM10; Dispersion model; Saraburi; Mineral products industry』

1. Introduction
2. Model descriptions
　2.1. The meteorological model
　2.2. The dispersion model
3. Result and discussion
　3.1 Model evaluation
　　3.1.1. Comparison of simulated winds and temperatures with observation
　　3.1.2. Comparison of simulated PM10 concentrations with observation
　3.2. Geographical distributions of PM10 concentrations
　3.3. Diurnal variations
4. Conclusions
Acknowledgements
References