AbstractBackground and ObjectiveChronic, 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.MethodsWe 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 (PM_2.5) 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.ResultsThere were no associations between mine fire‐related PM_2.5 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 PM_2.5, in the unadjusted and covariance‐adjusted models. Similar trends were observed with maximum PM_2.5.ConclusionThere was a moderate improvement in lung stiffness of children exposed to PM_2.5 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.