Sensitivities of Simulated Source Contributions and Health Impacts of PM2.5 to Aerosol Models

Chemical transport models are useful tools for evaluating source contributions and health impacts of PM2.5 in the atmosphere. We recently found that concentrations of PM2.5 compounds over Japan were much better reproduced by a volatility basis set model with an enhanced dry deposition velocity of HNO3 and NH3 compared with a two-product yield model. In this study, we evaluated the sensitivities to organic aerosol models of the simulated source contributions to PM2.5 concentrations and of PM2.5-related mortality. Overall, the simulated source contributions to PM2.5 were similar between the two models. However, because of the improvements associated with the volatility basis set model, the contributions of ammonia sources decreased, particularly in winter and spring, and contributions of biogenic and stationary evaporative sources increased in spring and summer. The improved model estimated that emission sources in Japan contributed 35%–48% of the PM2.5-related mortality in Japan. These values were higher than the domestic contributions to average PM2.5 concentrations in Japan (26%–33%) because the domestic contributions were higher in higher population areas. These results indicate that control of both domestic and foreign emissions is necessary to reduce health impacts due to PM2.5 in Japan.