Short-term effects of ambient air pollution exposure on lung function: A longitudinal study among healthy primary school children in China

Background: Short-term exposure to ambient air pollution has been associated with reduced lung function among asthmatic children. However, there is little information about the effects among healthy children, especially in areas with relatively high exposure background.

Objective: To examine the association between short-term effects of ambient air pollutants and lung function among healthy primary school-aged children in China.

Methods: A total of 334 healthy children (7-11 years) from four cities (Chengdu (Southwest China), Guangzhou (Southern China), Wuhan (Central China), and Xi'an (Northwest China)) in China with repeated lung function measurement in 2014-2016 were included. Daily ambient concentrations of PM_2.5, PM₁₀, NO₂, SO₂, mean temperature, and relative humidity data were obtained. Linear mixed model was used to estimate the percent change in lung function associated with per inter-quartile range (IQR) exposure (up to 3 days) increase after adjusting for confounders.

Results: Ambient PM_2.5 and PM₁₀ exposure were associated with decrements in lung function measurements. The moving average exposures generally showed stronger effect estimates than the single lag day exposures. An IQR increase in two-day average (lag01 day) PM₁₀ exposure (IQR, 144 μg/m³) was significantly associated with 2.56% decrease in FVC, 5.46% in FEV₁, 4.23% in PEF, and 7.35% in FEF_25%, respectively. The effect estimates were stronger after adjusting for gaseous pollutants in particulate matter (PM) models. The strengths of these associations were stronger in girls than those in boys.

Conclusion: Short-term exposure to PM was associated with reduced lung function in healthy children. The estimated adverse effects were greater in girls than in boys.