Early life exposure to an episode of extreme air pollution and lung function later in childhood: the Hazelwood Early Life Follow-up (ELF) Study.

Background Children are particularly vulnerable to air pollution, but the effects of early life exposure to acute, high-intensity pollution on later lung function remain poorly understood. We assessed the association between prenatal or infant exposure to fire-related fine particulate matter (PM 2.5 ) from a six-week coal mine fire and subsequent lung function. Methods We conducted a prospective cohort study of 213 children established to evaluate health effects of coalmine fire exposure. Individual daily mean and peak exposures to fire-related PM 2.5 were estimated using location diaries. Lung function was assessed using impulse oscillometry (resistance, reactance, area under the reactance curve at 5Hz) at 3, 7, and 9 years after the fire, and spirometry (FVC and FEV 1 ) at 9 years. Z-scores were calculated pre- and post-bronchodilator. Longitudinal and cross-sectional associations between PM 2.5 and lung function were assessed using linear mixed effect models (oscillometry) and linear regression (spirometry), adjusting for socioeconomic status, and maternal smoking and education. Results Children exposed to fire-related PM 2.5 during either the prenatal period or infancy showed no consistent associations with lung function at 9 years after the fire, or over time. Conclusion Prenatal and infant exposure to high-intensity air pollution was not clearly associated with lung function impairment. Infant exposure was previously associated with lung function impairment 3 years after the fire, however later estimates were imprecise and showed no clear association. While this may suggest potential normalisation over time, findings should be interpreted cautiously given the limited precision, potentially reflecting the small sample size. Larger studies with repeated measurements are needed to confirm this. Summary • We analysed the association of prenatal and infant exposure to fire-related PM 2.5 and lung function in children. • No persistent association between exposure and lung function, however findings should be interpreted cautiously given the lack of clear evidence.