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.
Keywords: Air pollution; asthma; coal industry; particulate matter; smoke.