Effects of Asian dust storms on mortality in three Asian cities

Abstract

Asian dust storms have affected several Asian countries being major issues for public health. ADS have different effect size on each country according to its geographical features. Considerable studies have found significant associations between ADS and morbidity. However, regarding the association between ADS and mortality, Japan found no association and in Taiwan and Korea, a few studies showed statistically significant ADS effects. This study aims to explore the effect of ADS on daily mortality in three Asian cities (Seoul, Taipei, Kitakyushu) and to find the different ADS effect by each city. We performed time-series analyses using genaralized additive model with Quasi-poisson regressions. PM10, relative humidity, barometric pressure, day of the week, temperature, season and time trends were controlled. We considered the single lag effect of ADS up to 7 days and adjusted for same lag day's PM10 concentrations. We found consistent results in Seoul as follows. ADS had adverse effects on all deaths(lag2-RR: 3.73%; 95%CI: 0.32,7.26) and circulatory deaths(lag1-RR: 7.79%; 95%CI: 1.05,14.99), whereas for respiratory deaths, ADS had protective effects(lag0-RR: -20.60%; 95%CI: -36.94,-0.02). In Taipei, ADS had protective effect on all deaths(lag0-RR: -3.52%; 95%CI: -6.27, -0.70), respiratory deaths(lag0-RR: -11.04%; 95%CI: -17.68,-3.86) and circulatory deaths(lag0-RR: -16.85%; 95%CI: -28.97,-2.67). In Kitakyushu, we found opposite results to Taipei. ADS had adverse effects on respiratory deaths(lag2-RR: 23.21%; 95%CI: 4.43,45.37) and circulatory deaths(lag0-RR: 53.94%; 95%CI: 9.13,117.14). We concluded that these results might be due to the difference in the number of ADS days by cities. Taipei has been affected by ADS frequently, so that people in Taipei might be more alert to ADS. Whereas, Kitakyushu is located relatively far from the origins and the least affected among three cities. Thus people in Kitakyushu might not be so worried than other two cities. Also, these results might suggest the effect of dust warning system to protect people.