For over 40 years the Northern Bohemia area of the Czech Republic has been characterized by heavy industrialization, open pit mining, and utilization of high sulfur brown coal by industry and in residential home heating. These conditions have resulted in severe environmental pollution and concern over evidence of adverse health effects for residents in the region. Beginning in August 1991, Czech scientists from the Teplice District Institute of Hygiene and U.S. Environmental Protection Agency researchers from the Health Effects Research Laboratory and the Atmospheric Research and Exposure Assessment Laboratory cooperated in conducting pilot studies in the Teplice District, which is centrally located in the industrialized area. These studies determined ambient concentrations and personal exposures to airborne polycyclic aromatic hydrocarbons (PAHs) and organic mutagens. Active personal air samplers were used in personal exposure studies of coal miners, policemen and other workers in the Teplice district. Mutagen concentrations and potency were determined by the Ames plate incorporation assay. The mutagenic potency of extractable organics from ambient air particles was higher than those for U.S. residential areas that are heavily impacted by wood smoke but similar to those from U.S. cities more heavily impacted by vehicle emissions.