The potential air pollution from the fuel combustion in the uncontrolled industrial boilers in Kocaeli, the most industrialized area in Turkey, was evaluated by using the emission factors determined based on the flue gas measurements conducted at over 100 industrial plants in the area. The emissions were modeled for conventional combustion pollutants by a Gaussian dispersion model to determine the possible contribution of these emissions to the background air pollution. Results show that the emission factors calculated for the pollutants including CO, SO,, NO,, PM and formaldehyde are comparable with those given in literature for other countries. On the other hand, the emission factors are laid in a wide range due to the presence of many factors affecting the emission of the pollutants, including the characteristics of fuel, boiler and combustion practice. The Gaussian air dispersion model applied by using the emission factors indicated that the effect of the industrial fuel combustion on the background air pollution was low for the conventional combustion pollutants despite the high number of industrial boilers in the area, suggesting the significant contribution of other sources, i.e. residential heating and mobile sources. (c) 2006 Elsevier Ltd. All rights reserved.