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

This panel study aimed to determine the acute effects of exposure to fine particulate matter (PM _2.5) on schoolchildren's pulmonary function.

We selected 51 schoolchildren aged 9-12 years attending a full-time boarding school in Beijing, China, measured the indoor and outdoor PM _2.5 concentrations for five consecutive days, calculated the PM _2.5 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 PM _2.5 and pulmonary function.

During the three surveys, the median PM _2.5 time-weighted individual exposure concentrations were 15.30 μg/m ³, 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 (FEV ₁) and forced expiratory volume in one second/forced vital capacity (FEV ₁/FVC) ( P < 0.05). The relevance analysis found that PM _2.5 had lag effect on schoolchildren's pulmonary function, each 10 μg/m ³increase in PM _2.5could cause largest decreases in FEF _25%-75%, FEV ₁/FVC, FEF _75%, and FEV ₁ on lag 0-1 d (80.44 mL/s, 35.85%, 78.58 mL/s, and 61.34 mL, respectively), and largest decreases in FEF _25% 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 PM _2.5 caused a decrease in FEV ₁/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.

Our findings show that acute PM _2.5 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 PM _2.5 than girls.