Acute Effects of Individual Exposure to Fine Particulate Matter on Pulmonary Function in Schoolchildren

Objective This panel study aimed to determine the acute effects of exposure to fine particulate matter(PM2.5) on schoolchildren’s pulmonary function.Methods We selected 51 schoolchildren aged 9–12 years attending a full-time boarding school in Beijing, China, measured the indoor and outdoor PM2.5 concentrations for five consecutive days,calculated the PM2.5 time-weighted individual exposure levels based on the school micro-environmental concentrations and the time activity pattern recorded by schoolchildren, measured schoolchildren’s pulmonary function on the fifth day. The survey was performed three times from December 2018 to April 2019. We used a linear mixed-effects model to evaluate the associations between PM2.5 and pulmonary function.Results During the three surveys, the median PM2.5 time-weighted individual exposure concentrations were 15.30 μg/m3, 48.92 μg/m^3, and 42.89 μg/m^3, respectively. There was a significant difference between the three surveys in vital capacity(VC), forced vital capacity(FVC), forced expiratory volume in one second(FEV1) and forced expiratory volume in one second/forced vital capacity(FEV1/FVC)(P <0.05). The relevance analysis found that PM2.5 had lag effect on schoolchildren’s pulmonary function,each 10 μg/m3 increase in PM2.5 could cause largest decreases in FEF25%–75%, FEV1/FVC, FEF75%, and FEV1 on lag 0–1 d(80.44 mL/s, 35.85%, 78.58 mL/s, and 61.34 mL, respectively), and largest decreases in FEF25% on lag 1 d(83.68 mL/s), in VC on lag 4 d(32.34 mL), and in FVC on lag 0–4 d(37.76 mL). Gender subgroup analysis revealed that the increase in PM2.5 caused a decrease in FEV1/FVC and VC on the day of physical examination only in boys, and on lag days it caused changes in different pulmonary function indicators, both for boys and girls, but most of the pulmonary function indicators decreased more in boys than in girls.Conclusion Our findings show that acute PM2.5 exposure has significant effects on pulmonary function within 0–4 d, on both small airway indicators and large airway indicators. Boys’ pulmonary function is more sensitive to PM2.5 than girls.