Effect of Hourly Concentration of Particulate Matter on Hospitalized Childrenʼs Peak Expiratory Flow

Abstract

PP-29-004 Background/Aims: There is little information about the possible association between hourly short-term air pollution and peak expiratory flow in asthmatic children. We collected and analyzed hourly air pollution data and peak expiratory flow data from asthmatic children. Methods: Subjects in this study were 17 patients aged 8–15 years with severe asthma who were hospitalized during 1 October 2000 through 24 December 2000. Measurements of peak expiratory flow and particulate matter (PM) were conducted immediately prior to medication twice a day, at 7 am and 7 pm, under the guidance of trained nurses. The changes in asthmatic children were estimated according to each 10 μg/m3 increment in PM with a 50% cut-off aerodynamic diameter of ≤2.5 μm (PM2.5) adjusted for sex, age at baseline survey, height at baseline survey, and temperature. Lagged-hour exposures of up to 24 hours were examined. Results: A decline in peak expiratory flow at 7 am was associated with the hourly concentration of PM2.5 during the period from lag 15 to lag 0. The largest effect size was −3.39 L/min (95% CI: −4.31, −2.46) for 10 μg/ of hourly concentration of PM2.5 between 11 pm and 12 pm on the previous night (lag 7). Some of the significant associations remained even after adjustment for other air pollutants. Conclusion: There was an association between a decline in peak expiratory flow and increased hourly concentration of PM2.5 up to 24 hours before peak expiratory flow measurement, especially in the morning.