An emissions inventory of primary air pollutants based on anthropogenic sources was prepared with 1-km spatial and 1-hour temporal resolution within an area of 85 km by 170 km centered on the metropolitan area of Istanbul, which is a megacity in Europe, as well as the economic, cultural, and financial center of Turkey. The emissions sources were broadly classified as industrial, vehicular and residential heating sources in a systematic manner. The emissions of five main pollutants, namely sulfur dioxide (SO2), particulate matter (PM10), carbon monoxide (CO), nitrogen oxides (NOx) and non-methane volatile organic compounds (NMVOCs), were estimated. Data on the activity levels of the various industries, fuel consumption in vehicles, and residential heating activities, along with the related emission factors from literature, were used for estimation of the emissions for the year 2007. The results show that SO2 emissions primarily came from the use of lignite and fuel oil in industrial plants and residential areas. Industry was the most polluting sector with regard to SO2 emissions, contributing about 83% of the total, while residential heating was the most polluting sector with regard to PM10 emissions, contributing 51% of the total. Traffic was also the most polluting sector for NOx, NMVOC and CO emissions, with the contributions of 89%, 68% and 68%, respectively. With regard to PM10 emissions, several sand and gravel processing plants, along with one big cement plant, were the main polluters in the metropolitan area.