Atmospheric transport route determines components of Asian dust and health effects in Japan

Asian dust (yellow sand) events are a frequent problem throughout Northeast Asia, where they produce a diverse range of health issues and symptoms in humans that have been widely reported. Asian dust includes soil-derived metals, anthropogenic metals, and many other air pollutants at various concentrations, depending on the atmospheric transport route. Here, we investigated the possible causes for the diversity in symptoms produced by Asian dust events, as reported in a questionnaire survey, on the basis of the dust components and estimated trajectories. Nine dust events were recorded and classified into three types on the basis of light detection and ranging (lidar) data: Type 1 events with high counts of non-mineral dust (spherical) particles, Type 2 events with high counts of mineral dust particles in comparison to non-mineral dust particles, and Type 3 events with very low counts of non-mineral dust particles as compared with other Asian dust events during the surveillance period. Ensemble backward trajectory analysis showed that the atmospheric transport route indeed accounted for the differences. Subjective symptom scores showed the greatest increase after exposure to Type 1 events and a decrease after exposure to Type 3 events. A variety of aerosols were detected concurrent with Asian dust events, and the link between health effects in humans and changes in pollutant levels was explored. The results suggest that the components of Asian dust should be considered when investigating related health effects. (C) 2011 Elsevier Ltd. All rights reserved.