Background: Few studies have assessed long-term effects of particulate matter (PM) with aerodynamic diameter < 2.5 mm (PM 2.5 ) on mortality for causes of cancer other than the lung; we assessed the effects on multiple causes. In Hong Kong, most people live and work in urban or suburban areas with high-rise buildings. This facilitates the estimation of PM 2.5 exposure of individuals, taking into account the height of residence above ground level for assessment of the long-term health effects with sufficient statistical power.Methods: We recruited 66,820 persons who were !65 in 1998 to 2001 and followed up for mortality outcomes until 2011. Annual concentrations of PM at their residential addresses were estimated using PM 2.5 concentrations measured at fixed-site monitors, horizontal-vertical locations, and satellite data. We