Asian dust is a risk of the incidence of acute myocardial infarction in the west side of Japan

Abstract

Backgrounds: Recently, Asian dust (AD) and air pollution have been recognized as a cause of cardiovascular diseases, such as ischemic stroke. However, the association between AD, a windblown sand dust originating from mineral soil in China and Mongolia, and the incidence of ischemic heart disease, such as acute myocardial infarction (AMI), is unknown. The sand dust is suspended in the air and transported overseas to the west side of Japan. The aim of the present study was to elucidate whether AD is associated with the incidence of AMI. Methods: We retrospectively investigated the date of hospitalizations due to AMI of 3068 consecutive patients from four AMI centers in Fukuoka, Japan from April 2003 to December 2010. Data on Asian dust, weather, and air pollutants were collected from Japan Meteorological Agency and National Institute for Environmental Studies. We applied the time-stratified case-crossover design to examine the association between AD and the incidence of AMI. This design is expected to adjust for individual confounders, season, time trend, and the day of week. Using conditional logistic regression, we estimated the odds ratios of AMI associated with AD. We also controlled for ambient temperature and relative humidity. Results: AD observed 0-4 days before the admission day was significantly associated with the incidence of AMI (odds ratio, 1.20; 95% confidence interval, 1.02-1.40). Especially AD observed 4 days ago was significantly associated (odds ratio, 1.33; 95% confidence interval, 1.05-1.69). Although we further adjusted for air pollutant including suspended particulate matter (SPM), photochemical oxi-dant (Ox), nitric oxide (NO2) and sulfur dioxide (SO2), the positive association between AD in day 0-4 and day4 and the risk of AMI was still observed. Conclusions: These data suggest that exposure to AD a few days ago may trigger the incidence of AMI.