He has conducted numerous observational epidemiological studies in New York City and other U.S. cities. His current investigations include: development of near-real time models to determine the impacts of weather and air pollution on respiratory and cardiovascular outcomes; identification of chemical components of ambient particulate matter associated with cardiovascular and respiratory outcomes; multi-city study of multiple air pollution effects on cardiovascular and respiratory mortality and morbidity; the role of traffic-related air pollution on respiratory and cardiovascular outcomes, and; characterization of spatial and temporal distributions of air pollutants in urban environments to identify sources that are particularly harmful. Michael Kleeman