This study, using case-crossover design, search a relationship between changing levels of air pollutants and asthma attack in asthma patients.

We searched the daily total number of asthmatic patients at hospital' s emergency room in Seoul, Korea by investigating total 49 general hospitals emergency room records. Otherwise, We investigated medical records of asthmatic patients at one of the 49 hospitals we have searched. We investigated addresses that they are living, diagnosis, smoking history, whether respiratory infection or not, medications. We analyzed the data by 1:m conditional logistic regression used when matched case-control study is analyzed. Control periods were chosen by bidirectional paired matching technique 7, 14 days before and after case periods.

the relative risk of asthmatic attack by 100 ppm ozone increase between June and September were 1.348(95 % CI = 1.010~1.619). Between November and February, the relative risk by 100 /m TSP increase, 100ppb sulfur dioxide and nitrogen dioxide were respectively 1.278(1.010~1.619), 1.237(1.019~1.502), 1.285(1.006~1.640). In stratified analysis, the relative risk were significant when the asthmatic patients were children aged 15 years or below, when there were respiratory infection, and when the patients took medications irregularly.

There was statistically significant association between ambient levels of air pollutants and asthmatic attack. So, we have to exert our efforts to minimize the air pollution effectively, to protect public health from air pollution.