Application of the CALINE4 air quality model and the TSI DustTrak for the prediction and measurement of roadside particulate matter and carbon monoxide levels in Bangkok

The CALINE4 air quality model, an air pollution management tool, was applied to calculate the immediate roadway contribution of air particulate matter <10µm (PM10) and carbon monoxide. Two busy roadside locations in Bangkok, Thailand, namely Ladphrao and Dindaeng, were selected for this study as they were adjacent to Thai Pollution Control Department (PCD) monitoring sites. Hourly ambient PM10 were measured using a portable TSI DustTrak monitor. The measurements were conducted across the period July 2001 to January 2002. The PCD monitoring data from Beta-Ray absorption and for carbon monoxide from non-dispersive infrared absorption were used as reference. Local emission factors from PCD were selected as input factor into the model. The model after trailing with gaseous carbon monoxide was adapted for particulate matter. The major factors that affected to model calculation of road contribution were wind direction, vehicle volume, height of receptor and composite emission factor. Minor factors were wind speed, temperature, distance of receptor and ambient pollutant concentration. The factors that appear to have little impact on model prediction are atmospheric stability class and mixing height. Comparison between DustTrak monitor and Beta-ray absorption show parallel trend with each other but more quality assurance works need to be done. Mode simulation indicates the usefulness of model as environmental assessment tool for downwind situation.