This comprehensive literature review to come out of HEI's Public Health and Air Pollution in Asia (PAPA) program builds on an initial assessment conducted in 2004 and describes the current scope of the Asian literature on the health effects of outdoor air pollution, enumerating and classifying more than 400 studies. In addition, the report includes a systematic and quantitative assessment of 82 time-series studies of daily mortality and hospital admissions for cardiovascular and respiratory disease. The studies covered in the current review include the PAPA time-series studies in four Asian cities (Research Report 154), as well as a first-ever critical and qualitative analysis of Asian studies of long-term exposure to air pollution and chronic respiratory disease, lung cancer, and adverse reproductive outcomes that describes both what the studies tell us and the continuing uncertainties and research needs. The report also provides a broad overview of the status of and trends in air pollution sources, emissions, and exposures in the developing countries of Asia, as well as factors related to urban development, population health, and public policy that set the context for the public health effects of air pollution. The review concludes by placing the Asian health effects studies in the context of the worldwide literature, identifies gaps in knowledge, and recommends approaches by which to address them.