Asian dust and daily emergency ambulance calls among elderly people in Japan: an analysis of its double role as a direct cause and as an effect modifier.

Abstract

To evaluate the direct health effects of Asian dust on ambulance calls and its role as an effect modifier on the effects of anthropogenic air pollution in Japan. The subjects were 51,945 elderly residents who visited hospital emergency departments from 2006 to 2010. We evaluated the impact of Asian dust by time-series analyses and the excess risk from suspended particulate matter (SPM) stratified by Asian-dust exposure. Asian dust was associated with daily ambulance calls due to all-cause, cardiovascular, and respiratory disease independently of SPM, for example, the relative risk per interquartile increase in Asian dust (3-day lag) was 1.021 (1.002 to 1.039) for cardiovascular disease. Furthermore, Asian dust modified the effects of SPM on cardiovascular and respiratory diseases. Asian dust had adverse effects and modified the effect of SPM.