Association between PM2.5 from a coal mine fire and FeNO concentration 7.5 years later.

BACKGROUND AND AIM: There are few long-term studies of respiratory health effects of landscape fires, despite increasing frequency and intensity due to climate change. We investigated the association between exposure to coal mine fire PM2.5 and fractional exhaled nitric oxide (FeNO) concentration 7.5 years later. METHODS: Adult residents of Morwell, who were exposed to the 2014 Hazelwood mine fire over 6 weeks, and unexposed residents of Sale, participated in the Hazelwood Health Study Respiratory Stream in 2021, including measurements of FeNO concentration, a marker of eosinophilic airway inflammation. Individual exposure to coal mine fire PM2.5 was modelled and mapped to time-location diaries. The effect of exposure to PM2.5 on log-transformed FeNO in exhaled breath was investigated using multivariate linear regression models in the entire sample and stratified by potentially vulnerable subgroups. RESULTS: A total of 326 adults (mean age: 57 years) had FeNO measured. The median FeNO level (interquartile range [IQR]) was 17.5 [15.0] ppb, and individual daily exposure to coal mine fire PM2.5 was 7.2 [13.8] µg/m3. We did not identify evidence of association between coal mine fire PM2.5 exposure and FeNO in the general adult sample, nor in various potentially vulnerable subgroups. The point estimates were consistently close to zero in the total sample and subgroups. CONCLUSION: Despite previous short-term impacts on FeNO and respiratory health outcomes in the medium term, we found no evidence that PM2.5 from the Hazelwood coal mine fire was associated with any long-term impact on eosinophilic airway inflammation measured by FeNO levels.

Are e-cigarette use and vaping associated with increased respiratory symptoms and poorer lung function in a population exposed to smoke from a coal mine fire?

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.

Long-term impact of coal mine fire smoke on lung mechanics in exposed adults.

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 (PM2.5 ). 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 PM2.5 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 PM2.5 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 PM2.5 and worsening lung mechanics, including a reduction in post-bronchodilator (BD) Xrs5 and an increase in AX5. A 10 µg/m3 increase in mine fire-related PM2.5 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 PM2.5 exposure to coal mine fire smoke. These results should inform public health policies and planning for future events.