Reductions of PM2.5 Air Concentrations and Possible Effects on Premature Mortality in Japan

The current study estimates premature mortality caused by long-term exposure to elevated concentrations of PM2.5 (particulate matter with aerodynamic diameter equal to or less than 2.5 μm) in Japan from 2006 to 2009. The premature mortality is calculated based on a relative risk of 1.04 (95 % CI, 1.01–1.08) per 10 μg m−3 increase above the annual mean limit of 10 μg m−3 taken from the World Health Organization Air Quality Guidelines. The spatiotemporal variations of PM2.5 are estimated based on the measurements of suspended particulate matter (SPM) (with aerodynamic diameter approximately less than 7.0 μm) at 1,843 monitors. The improvements of air quality in Japan by reducing the emissions of SPM from 2006 to 2009 could save 3,602 lives based on a reduction target of 10 μg m−3 annual mean concentration. This finding could be a tangible benefit gained by reducing the emissions of particulate matter in Japan.