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Background and Objectives: The Hazelwood Health Study was set up to study long-term health effects of a mine fire that blanketed residents of the Latrobe Valley with smoke for 45 days in 2014. The Respiratory Stream specifically assessed the impact of fine particulate matter <2.5 μm diameter (PM 2.5 ) exposure from mine fire smoke on lung health. The multiple breath nitrogen washout (MBW) test assesses ventilation heterogeneity, which may detect sub-clinical airways dysfunction not identified using standard tests such as spirometry. This analysis assessed the association of PM 2.5 exposure with measures of ventilation heterogeneity., Methods: Exposed (Morwell) and unexposed (Sale) participants were recruited 3.5-4 years after the fire from those who had participated in an Adult Survey. MBW was performed to measure lung clearance index (LCI), functional residual capacity (FRC), acinar (Sacin) and conductive (Scond) ventilation heterogeneity. PM 2.5 exposure was estimated with emission and chemical transport models. Multivariable linear regression models were fitted controlling for confounders., Results: We recruited 519 participants. MBW tests were conducted on 504 participants with 479 acceptable test results (40% male; 313 exposed, 166 unexposed). Exposure to mine fire-related PM 2.5 was associated with increasing Scond (β = 1.57/kL, 95%CI: 0.20-2.95, p = 0.025), which was comparable to the estimated effect on Scond of 4.7 years of aging. No other MBW outcomes were statistically different., Conclusion: Increasing exposure to PM 2.5 was associated with increased ventilation heterogeneity in the conductive region of the lungs 4 years after the event., (© 2024 The Author(s). Respirology published by John Wiley & Sons Australia, Ltd on behalf of Asian Pacific Society of Respirology.)

Background: In 2014, the Hazelwood coalmine fire shrouded the regional Australian town of Morwell in smoke and ash for 6 weeks. One of the fire's by-products, PM 2.5 , is associated with an increased risk of COVID-19 and severe disease. However, it is unclear whether the effect persisted for years after exposure. In this study, we surveyed a cohort established prior to the pandemic to determine whether PM 2.5 from the coalmine fire increased long-term vulnerability to COVID-19 and severe disease., Methods: From August to December 2022, 612 members of the Hazelwood Health Study's adult cohort, established in 2016/17, participated in a follow-up survey that included standardized items to capture COVID-19 cases, as well as questions about hospitalization and vaccinations. Associations were evaluated in crude and adjusted logistic regression models., Results: A total of 268 (44%) participants self-reported or met symptom criteria for having had COVID-19 at least once. All models found a positive association, with odds of COVID-19 increasing by between 4% and 30% for a 10 μg/m 3 increase in coalmine fire-related PM 2.5 exposure. However, the association was significant in only 2 of the 18 models. There were insufficient hospitalizations to examine severity (n = 7; 1%)., Conclusion: The findings are inconclusive on the effect of coalmine fire-related PM 2.5 exposure on long-term vulnerability to COVID-19. Given the positive association that was robust to modelling variations as well as evidence for a causal mechanism, it would be prudent to treat PM 2.5 from fire events as a long-term risk factor until more evidence accumulates., (© 2023 The Authors. Respirology published by John Wiley & Sons Australia, Ltd on behalf of Asian Pacific Society of Respirology.)

Background and Objective: E-cigarette use has become increasingly prevalent, but there is some evidence demonstrating potential harms with frequent use. We aimed to identify the profiles of e-cigarette users from a regional community in Australia and investigate the associations of e-cigarettes with respiratory symptoms and lung function., Methods: A total of 519 participants completed a cross-sectional study. Exposure to e-cigarettes was collected via a validated questionnaire. Respiratory symptoms were evaluated via a self-reported questionnaire and lung function measured with spirometry and forced oscillation technique (FOT). Linear and logistic regression models were fitted to investigate the associations between e-cigarettes and outcomes, while controlling for confounders such as tobacco smoking., Results: Of the 519 participants, 46 (9%) reported e-cigarette use. Users tended to be younger (mean ± SD 45.2 ± 14.5 vs. 55.3 ± 16.0 years in non-users), concurrently using tobacco products (63% vs. 12% in non-users), have a mental health diagnosis (67% vs. 37% in non-users) and have self-reported asthma (63% vs. 42% in non-users). After controlling for known confounders, chest tightness (OR = 2.4, 95% CI 1.2-4.9, p = 0.02) was associated with e-cigarette use. Spirometry was not different after adjustment for confounding. However, FOT showed more negative reactance and a greater area under the reactance curve in e-cigarette users than non-users., Conclusion: E-cigarette use was associated with increased asthma symptoms and abnormal lung mechanics in our sample, supporting a potential health risk posed by these products. Vulnerable populations such as young adults and those with mental health conditions have higher usage, while there is high concurrent tobacco smoking., (© 2021 Asian Pacific Society of Respirology.)

Background and Objective: In 2014, a 6-week-long fire at the Hazelwood coal mine exposed residents in the adjacent town of Morwell to high concentrations of fine particulate matter with an aerodynamic diameter < 2.5 μm (PM 2.5 ). The long-term health consequences are being evaluated as part of the Hazelwood Health Study., Methods: Approximately 3.5-4 years after the mine fire, adults from Morwell (n = 346) and the comparison town Sale (n = 173) participated in the longitudinal Respiratory Stream of the Study. Individual PM 2.5 exposure was retrospectively modelled. Lung mechanics were assessed using the forced oscillation technique (FOT), utilizing pressure waves to measure respiratory system resistance (Rrs) and reactance (Xrs). Multivariate linear regression was used to evaluate associations between PM 2.5 and transformed Rrs at 5 Hz, area under the reactance curve (AX5) and Xrs at 5 Hz controlling for key confounders., Results: There were clear dose-response relationships between increasing mine fire PM 2.5 and worsening lung mechanics, including a reduction in post-bronchodilator (BD) Xrs5 and an increase in AX5. A 10 μg/m 3 increase in mine fire-related PM 2.5 was associated with a 0.015 (95% CI: 0.004, 0.027) reduction in exponential (Xrs5) post-BD, which was comparable to 4.7 years of ageing. Similarly, the effect of exposure was associated with a 0.072 (0.005, 0.138) increase in natural log (lnAX5) post-BD, equivalent to 3.9 years of ageing., Conclusion: This is the first study using FOT in adults evaluating long-term respiratory outcomes after medium-term ambient PM 2.5 exposure to coal mine fire smoke. These results should inform public health policies and planning for future events., (© 2021 Asian Pacific Society of Respirology.)