Air pollution data in Bangkok, Thailand, indicate that levels of particulate matter with aerodynamic diameter ? 10 ?m (PM10) are significantly higher than in most cities in North America and Western Europe, where the health effects of PM10 are well documented. However, the pollution mix, seasonality, and demographics are different from those in developed Western countries. It is important, therefore, to determine whether the large metropolitan area of Bangkok is subject to similar effects of PM10. This study was designed to investigate the mortality risk from air pollution in Bangkok, Thailand.