The acute effects of particulate air pollution on lung function in asthmatic children: A multicenter study with intensively repeated measurements

Evidence on the comparative effects of fine particulate matter (PM2.5) and coarse particulate matter (PM10-2.5) on the lung function of asthmatic children remained limited and inconsistent. This study aims to explore the acute effect of PM2.5 and PM10-2.5 on dynamic forced expiratory volume in 1 s (FEV1) and peak expiratory flow (PEF) among asthmatic children. We conducted a multicenter study and obtained intensively repeated measurements of FEV1 and PEF of clinically diagnosed asthmatic children in 89 Chinese cities from January 2017 to May 2021. Linear mixed-effects models combined with a polynomial distributed lag model were employed to evaluate the cumulative lag effect of PM2.5 and PM10-2.5 on daily FEV1 and PEF among asthmatic children. We also evaluated the effect modifications by sex, age, testing time, season, and region. A total of 590 clinically diagnosed asthmatic children with over 0.18 million dynamic lung function records were included in this study. The adverse effect of particulate matter on lung function occurred in a short term and could last for around one week. Specifically, both PM10-2.5 and PM2.5 were associated with decreases in PEF, but only PM10-2.5 could impair the measurements of FEV1. We found that an interquartile range increase in PM10-2.5 and PM2.5 were associated with 5.40 [95% confidence interval (CI): 0.88, 9.92] mL/s and 10.48 (95%CI: 5.14, 15.81) mL/s decrease in PEF, 6.46 (95%CI: 4.53, 8.40) mL and 0.25 (95%CI: −2.03, 2.54) mL decreases in FEV1, respectively. And the estimated effect of PM10-2.5 was stronger than PM2.5 on FEV1. Besides, these changes were larger in the evening and the south region of China. In conclusion, short-term exposure to both PM2.5 and PM10-2.5 could decrease the daily lung function of asthmatic children. The impact of PM10-2.5 was more hazardous than PM2.5.