Serum levels of Clara cell protein and short- and long-term exposure to particulate air pollution in adolescents

Abstract

Background: Studies in populations have shown that particulate air pollution is associated with changes in lung function in adolescents. Objective: We investigated the effect of short- and long-term exposure to particulate matter (PM10) on pulmonary health of adolescents, using serum lung Clara cell protein (CC16) as a biomarker for respiratory epithelium integrity. Methods: We measured serum CC16 in 825 adolescents (57% girls, mean age: 15 years). Short-term and long-term exposure to ambient PM10 was estimated for each participant’s home address using a kriging interpolation method. To explore the relationship between PM10 and serum CC16 we applied restricted cubic splines with 5 knots located at the 5th, 25th, 50th, 75th and 95th percentiles of the PM10 distribution. Results: After adjustment for potential covariates, the analysis showed strong associations between PM10 concentrations during a preceding week and serum CC16 levels. An increase from 20 to 30 µg/m³ in mean PM10 in the week before clinical examination was associated with a substantial increase of 0.93 µg/l (0.14 to 1.17, p=0.021) in serum CC16 levels. The association flattens at higher concentrations (mean week averages of more than 30 µg/m³). There was no evidence of an association between long-term exposure to PM10 and serum CC16 concentrations. Conclusions: Our findings suggest that short-term exposure to particulate air pollution may compromise the integrity of the lung epithelium and lead to increased epithelial barrier permeability in the lungs of adolescents, even at low concentrations.