Contrasting Health Outcomes following a Severe Smoke Episode and Ambient Air Pollution in Early Life: Findings from an Australian Data Linkage Cohort Study of Hospital Utilization.

BACKGROUND: Episodic spikes in air pollution due to landscape fires are increasing, and their potential for longer term health impacts is uncertain. OBJECTIVE: Our objective is to evaluate associations between exposure in utero and in infancy to severe pollution from a mine fire, background ambient air pollution, and subsequent hospital care. METHODS: We linked health records of births, emergency department (ED) visits, and hospitalizations of children born in the Latrobe Valley, Australia, 2012-2015, which included a severe pollution episode from a mine fire (9 February 2014 to 25 March 2014). We assigned modeled exposure estimates for fire-related and ambient particulate matter with an aerodynamic diameter of 2.5µm (PM2.5) to residential address. We used logistic regression to estimate associations with hospital visits for any cause and groupings of infectious, allergic, and respiratory conditions. Outcomes were assessed for the first year of life in the in utero cohort and the year following the fire in the infant cohort. We estimated exposure-response for both fire-related and ambient PM2.5 and also employed inverse probability weighting using the propensity score to compare exposed and not/minimally exposed children. RESULTS: Prenatal exposure to fire-related PM2.5 was associated with ED presentations for allergies/skin rash [odds ratio (OR)=1.34, 95% confidence interval (CI): 1.01, 1.76 per 240 µg/m3 increase]. Exposure in utero to ambient PM2.5 was associated with overall presentations (OR=1.18, 95% CI: 1.05, 1.33 per 1.4 µg/m3) and visits for infections (ED: OR=1.13, 95% CI: 0.98, 1.29; hospitalizations: OR=1.23, 95% CI: 1.00, 1.52). Exposure in infancy to fire-related PM2.5 compared to no/minimal exposure, was associated with ED presentations for respiratory (OR=1.37, 95% CI: 1.05, 1.80) and infectious conditions (any: OR=1.21, 95% CI: 0.98, 1.49; respiratory-related: OR=1.39, 95% CI: 1.05, 1.83). Early life exposure to ambient PM2.5 was associated with overall ED visits (OR=1.17, 95% CI: 1.05, 1.30 per 1.4 µg/m3 increase). DISCUSSION: Higher episodic and lower ambient concentrations of PM2.5 in early life were associated with visits for allergic, respiratory, and infectious conditions. Our findings also indicated differences in associations at the two developmental stages. https://doi.org/10.1289/EHP12238.