• Asian dust storms;
  • asthma;
  • PM10 concentration;
  • daily clinic visit;
  • paired t-test


East Asia, including the Korean peninsula, is affected by dust storms originating from the deserts of Mongolia and China, especially in spring. These are called Asian dust storm (ADS) events. ADS events frequently generate ambient dust particles less than 10 µm in diameter. Particles of this size are known to be associated with adverse health effects. The aim of this study is to investigate the possible adverse effects of ADS on the asthma symptoms of residents of Seoul, South Korea, during the period 2005–2008. A paired t-test was used to compare daily medical treatment counts for asthma disease on ADS events with those on the comparison days. ‘Comparison days’ is defined as the 7 days before and after the ADS episodes, referred to as index days in this study. The estimated percentage increase in the rate of asthma treatments after the ADS event, using 4–6 day moving means, was about 18%. This shows a statistically significant association between ADS events and asthma treatment counts 4–6 days after the ADS event. It was also found that the percentage increase in asthma treatments on index days with high levels of PM10 concentration was about 22% (P < 0.05) in cases with a 6 day lag. This study generates evidence that ADS events are significantly associated with asthma symptoms and that increased PM10 levels may aggravate asthma disease. Copyright © 2013 Royal Meteorological Society