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 PM_2.5 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 PM_2.5 was modelled and mapped to time-location diaries. The effect of exposure to PM_2.5 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 PM_2.5 was 7.2 [13.8] µg/m³. We did not identify evidence of association between coal mine fire PM_2.5 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 PM_2.5 from the Hazelwood coal mine fire was associated with any long-term impact on eosinophilic airway inflammation measured by FeNO levels. [ABSTRACT FROM AUTHOR]