Exposure to PM2.5 and Lung Function Growth in Pre- and Early-Adolescent Schoolchildren: A Longitudinal Study Involving Repeated Lung Function Measurements in Japan

Rationale: Epidemiological evidence indicates that ambient exposure to particulate matter ⩽2.5 μm in aerodynamic diameter (PM 2.5 ) has adverse effects on lung function growth in children, but it is not actually clear whether exposure to low-level PM 2.5 results in long-term decrements in lung function growth in pre- to early-adolescent schoolchildren. Objectives: To examine long-term effects of PM 2.5 within the 4-year average concentration range of 10-19 μg/m 3 on lung function growth with repeated measurements of lung function tests. Methods: Longitudinal analysis of 6,233 lung function measurements in 1,466 participants aged 8-12 years from 16 school communities in 10 cities around Japan, covering a broad area of the country to represent concentration ranges of PM 2.5 , was done with a multilevel linear regression model. Forced expiratory volume in 1 second, forced vital capacity (FVC), and maximal expiratory flow at 50% of FVC were used as lung function indicators to examine the effects of 10-μg/m 3 increases in the PM 2.5 concentration on relative growth per each 10-cm increase in height. Results: The overall annual mean PM 2.5 level was 13.5 μg/m 3 (range, 10.4-19.0 μg/m 3 ). We found no association between any of the lung function growth indicators and increases in PM 2.5 levels in children of either sex, even after controlling for potential confounders. Analysis with two-pollutant models with O 3 or NO 2 did not change the null results. Conclusions: This nationwide longitudinal study suggests that concurrent, long-term exposure to PM 2.5 at concentrations ranging from 10.4 to 19.0 μg/m 3 has little effect on lung function growth in preadolescent boys or pre- to early-adolescent girls.