Association between exposure to particulate matter and school absences in Korean asthmatic adolescents

BACKGROUND: Because particulate matter (PM) and asthma are closely related, the prevalence of school absence among adolescents with asthma can be affected by the concentration of PM. We aimed to investigate the relationship between school absences due to asthma and the total number of days that the PM concentration exceeded the standard. METHODS: We used the data from the 16th Korea Youth Risk Behavior Survey and the PM levels of 17 metropolitan cities and provinces gathered from the AirKorea. Information on the characteristics of asthmatic adolescents and the prevalence of school absence was obtained using a questionnaire, while the PM levels based on the total number of days with poor and very poor PM grades were collected from the AirKorea website. Both χ(2) test and logistic regression analysis were performed using the weights presented in the original dataset. RESULTS: In the case of particulate matter of 10 microns in diameter or smaller (PM(10)), the odds ratio (OR) after adjusting for confounders (sex, school year, body mass index, smoking history, diagnosis of allergic rhinitis, diagnosis of atopic dermatitis and city size) was 1.07 (95% confidence interval [CI]: 1.01–1.13) for absents due to asthma when the total days of poor and very poor grades of PM(10) (81 μg/m(3) or higher) increased by 1 day. In the analysis of particulate matter of 2.5 microns in diameter or smaller (PM(2.5)), the OR after adjusting for confounders was 1.01 (95% CI: 1.00–1.03) for absents due to asthma when the total number of days with poor and very poor PM(2.5) grades (36 μg/m(3) or higher) increased by 1 day. CONCLUSIONS: A significant association was observed between the total number of days of poor and very poor PM(10) and PM(2.5) grades and school absence due to asthma; PM can cause asthma exacerbation and affect the academic life.