Scientists from the United States and the Czech Republic recently completed a study to investigate the ambient air quality impact of industrial and motor vehicle sources in Teplice. The primary monitoring sites were located in Teplice in northwestern Bohemia and Prachatice in southern Bohemia. Fine particulate air samples were composed mainly of organic carbon and sulfate and had smaller amounts of trace metals. The Teplice ambient monitoring and source characterization data were then used in receptor modeling calculations, which indicated that home heating and power plant emissions were responsible for up to 80% of ambient fine particle mass concentrations observed during winter inversion episodes. Motor vehicles, incinerators and windblown dust contributed to the balance of the inhalable particles.