Modeling of effects of fuel quality on the emissions of major pollutants (NOx SO2, CO2 and PM) and eight trace elements (As, Co, Cr, La, Mo, Ni, Sb and U) from a 300-MW boiler unit fired with Thai lignite was the main focus of this study. The NOx and SO2 emission models were validated with the use of experimental data. Emission rates and specific emissions (per MW h) of the major pollutants and trace elements were quantified by including efficiencies of the flue gas desulphurization system and electrostatic precipitators in the computations. As shown in this work, the contributions of 300-MW boiler units fired with Thai lignite to the "greenhouse" and "acid rain" gas emissions in the region are significant. Additionally, substantial amounts of hazardous As, Cr and Ni are emitted from the boiler units into the atmosphere via fly ash particles. (C) 2006 Elsevier Ltd. All rights reserved.