Relationship Of Air Pollution And Childhood Asthma In Hangzhou

In order to estimate the effect of air pollution on childhood asthma, and evaluate the potential risk factors for childhood asthma, the case-crossover study was used to analyze the date for daily air pollution and hospital visits for childhood asthma in Hangzhou, China from January 1st,2011 to December 31th,2012. According to season-stratification, smog-stratification and area-stratification, the relationship of air pollution and childhood asthma was respectively studied. The conclusions include:(1) During the whole study period of 731 days, the frequency of smog weather was 40.9%. The frequency in winter, which was up to 54%, was the highest, followed by spring and autumn. The smog weather occurred frequently from December to next March, and the peaks appeared in September. Similarly, the average concentrations of atmospheric pollutants such as PM2.5, PM10, NO2 and SO2 were all higher in winter and spring, and the lowest in summer. The monthly frequencies of smog weather had positive associations with the monthly average concentrations of atmospheric pollutants. The "day of the week" effects of daily average concentrations of PM2.5 and NO2 were more obvious than that of PM10 and SO2. Compared with other days in weeks, the daily average concentrations were higher on Thursday, Friday and Saturday.(2) During the study period, the number of hospital visits of childhood asthma in urban areas of Hangzhou was 5303, and which in Yuhang district of Hangzhou was 1426. The percentage of boy was 57.9%, and which of girl was 42.1%. The average age of the patients was 7 years. The hospital visits on smoggy days were 241 more cases or 7.43% higher than that on non-smoggy days. The number of hospital visits of childhood asthma was highest in winter, and lowest in summer, and it reached the peak in November and December, than fell to trough in April. Hospital visits were more on Sunday, Monday and Tuesday, and fewest on Friday.(3) The effect of air pollution on childhood asthma in Yuhang district was more significant, compared to which in urban areas. The main potential risk factors for childhood asthma in urban areas were PM2.5, NO2 and SO2, and that in Yuhang were NO2 and PM10.(4) The effect of air pollution on childhood asthma in smoggy days was more significant, compared to that in non-smoggy days. The main potential risk factors for childhood asthma in smoggy days were PM2.5, NO2 and SO2, and that in non-smoggy days was SO2.(5) The effect of air pollution on childhood asthma in autumn was the most significant, followed by spring and winter. The main potential risk factors in autumn were PM2.5, NO2 and SO2, and which in spring were NO2 and SO2, and that in winter was NO2. There was no risk factor found in summer. The smoggy weather had significant effects on hospital visits for childhood asthma.The results indicated that:Under different conditions, each atmospheric pollutant might be a risk factor for childhood asthma. There was a positive association between the aggravation of air pollution and the increase of hospital visits for childhood asthma, which was unlikely due to bias.This study provides valuable information and scientific bases for preventing asthma, controlling air pollution, and formulating atmospheric environmental quality standards suited to local places.