Relationship between exposure to fine particulates and ozone and reduced lung function in children.

BACKGROUND

A limited number of studies have reported an association between long-term exposure to ambient air pollutants and lung function growth among children, with inconclusive results.

OBJECTIVES

To assess the relationship between air pollutant exposure and lung function growth, and to examine potential sex differences in the susceptibility of lung function growth to air pollution.

METHODS

We conducted a two-year prospective cohort study of Taiwanese children aged 12 at baseline who were followed from October 1, 2007 to November 31, 2009. The study population comprised 2941 non-smoking children who completed pulmonary function tests at both baseline and follow-up surveys. We applied spatial modeling for individual-level exposure assessment to capture relevant exposures and also attempted to eliminate potential community-level confounding. The exposure parameters were annual averages and values calculated from 24-hourly PM2.5 and 8-hourly ozone (O3) concentrations, corresponding to the residential addresses over the study period. The effect estimates were presented as lung function growth deficits per interquartile range (IQR) for PM2.5 and O3.

RESULTS

In a multiple linear mixed effect model, adjusted for confounding, growth deficits in the forced vital capacity (FVC), forced expiration volume in 1s (FEV1), and forced expiratory flow between the 25th and 75th percentiles of the FVC were associated with increased exposure to PM2.5 and O3. For example, greater exposure to PM2.5 (IQR, 17.92μg/m(3)) was associated with an annual deficit in FVC growth of 75mL in boys and 61mL in girls (p for interaction <0.05). Similar associations were found for O3.

CONCLUSIONS

The study provides evidence that long-term exposure to PM2.5 and O3 may have a detrimental effect on the development of lung function in children. The estimated deficits were generally larger in boys, compared to girls.