Ventilation heterogeneity is increased in adults exposed to coal mine fire-related PM2.5.

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 (PM2.5) 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 PM2.5 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. PM2.5 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 PM2.5 was associated with increasing Scond (ß = 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 PM2.5 was associated with increased ventilation heterogeneity in the conductive region of the lungs 4 years after the event.

The impact of the Hazelwood coal mine fire smoke exposure on asthma.

OBJECTIVE: In 2014, a fire at an open cut coal mine in South-eastern Australia burned for about 6 weeks. Residents of the adjacent town were exposed to high levels of fine particulate matter (PM2.5) during this period. Three and a half years after the event, this study aimed to investigate potential long-term impacts of short-term exposure to coal mine fire smoke on asthma. METHODS: A cross-sectional analysis was undertaken in a group of exposed participants with asthma from Morwell (n = 165) and a group of unexposed participants with asthma from the control town of Sale (n = 64). Exposure was determined by modeled PM2.5 data for the mine fire period. Respiratory symptoms were assessed with a validated respiratory health questionnaire and symptom severity score. Asthma control was assessed with a validated questionnaire. Lung function testing included spirometry, bronchodilator response, and fraction of exhaled nitric oxide. RESULTS: There was no evidence that exposed participants had more severe asthma symptoms, worse lung function, or more eosinophilic airway inflammation than unexposed participants. However, there was some evidence that Morwell participants had more uncontrolled than well-controlled asthma, compared to the participants from Sale (adjusted relative risk ratio 2.71 95% CI: 1.02, 7.21, p = .046). CONCLUSION: Three and a half years after exposure, coal mine fire smoke did not appear to be associated with more severe asthma symptoms or worse lung function but might be associated with poorer asthma control.

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.

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.

Chronic Obstructive Pulmonary Disease in Adults Exposed to Fine Particles from a Coal Mine Fire.

Rationale: In 2014, the Hazelwood open-cut coal mine in southeastern Australia burned for 6 weeks, exposing nearby residents to high concentrations of fine particulate matter (PM2.5). The long-term health consequences are unknown and are being evaluated as part of the Hazelwood Health Study. Objectives: To explore the association between PM2.5 exposure and chronic obstructive pulmonary disease (COPD). Methods: A sample of 346 exposed and 173 unexposed adults participated in the longitudinal Respiratory Stream of the Hazelwood Health Study. Participants underwent spirometry and gas transfer measurements and answered validated respiratory questionnaires 3.5-4 years after the fire. Individual-level mine fire-related PM2.5 exposure was modeled. Multivariate linear regression and logistic models were fitted to analyze associations between mean and peak PM2.5 exposure and clinical outcomes, stratified by smoking status. Results: A 10 µg/m3 increase in mean PM2.5 exposure was associated with a 69% (95% confidence interval [CI], 11-158%) increase in odds of spirometry consistent with COPD among nonsmokers and increased odds of chest tightness (odds ratio [OR], 1.30; 95% CI, 1.03-1.64) and chronic cough (OR, 1.24; 95% CI, 1.02-1.51) in the previous 12 months in all participants. For current smokers, increments in mean PM2.5 exposure were associated with higher odds of chronic cough in the preceding 12 months (OR, 2.13; 95% CI, 1.24-3.65). Conclusions: Almost 4 years after a 6-week period of coal fire PM2.5 exposure, we identified a dose-response association between exposure and COPD in nonsmokers. With climate change a likely contributor to increased risk of landscape fires, the findings will inform policy decisions during future sustained smoke events.