Lung function changes in children exposed to mine fire smoke in infancy

Abstract

Background and Objective: Chronic, low-intensity air pollution exposure has been consistently associated with reduced lung function throughout childhood. However, there is limited research regarding the implications of acute, high-intensity air pollution exposure. We aimed to determine whether there were any associations between early life exposure to such an episode and lung growth trajectories. Methods: We conducted a prospective cohort study of children who lived in the vicinity of the Hazelwood coalmine fire. Lung function was measured using respiratory oscillometry. Z-scores were calculated for resistance (R5) and reactance at 5 Hz (X5) and area under the reactance curve (AX). Two sets of analyses were conducted: (i) linear regression to assess the cross-sectional relationship between post-natal exposure to mine fire-related particulate matter with an aerodynamic diameter of less than 2.5 micrometres (PM2.5) and lung function at the 7-year follow-up and (ii) linear mixed-effects models to determine whether there was any association between exposure and changes in lung function between the 3- and 7-year follow-ups. Results: There were no associations between mine fire-related PM2.5 and any of the lung function measures, 7-years later. There were moderate improvements in X5 (β: −0.37 [−0.64, −0.10] p = 0.009) and AX (β: −0.40 [−0.72, −0.08] p = 0.014), between the 3- and 7-year follow-ups that were associated with mean PM2.5, in the unadjusted and covariance-adjusted models. Similar trends were observed with maximum PM2.5. Conclusion: There was a moderate improvement in lung stiffness of children exposed to PM2.5 from a local coalmine fire in infancy, consistent with an early deficit in lung function at 3-years after the fire that had resolved by 7-years.