Respiratory symptoms after coalmine fire and pandemic: a longitudinal analysis of the Hazelwood Health Study adult cohort

Background Extreme but discrete fine particle <2.5μm (PM2.5) exposure is associated with higher prevalence of respiratory symptoms. It is unknown whether these effects abate, persist, or worsen over time, nor whether COVID-19 exacerbates PM2.5 effects. Methods We analysed longitudinal survey data from a cohort residing near a 2014 coalmine fire in regional Australia. A 2016/2017 survey included n=4,056 participants, of whom n=612 were followed-up in 2022. Items include questions about 7 respiratory symptoms, history of COVID-19, and time-location diaries that were combined with geospatial models of fire-related PM2.5. Associations were examined using logistic and mixed-effects logistic regressions. Results PM2.5 exposure predicted higher prevalence of chronic cough and current wheeze 2-3 years post-fire. At the 2022 follow-up, PM2.5 exposure was associated with worsening prevalence of chronic cough and possibly current wheeze. While were no detectable interaction effects between PM2.5 and COVID-19, participants with a history of COVID-19 exhibited more significant associations between PM2.5 exposure and respiratory symptoms. Discussion Short-term but extreme PM2.5 may increase the long-term prevalence of chronic cough, while COVID-19 may exacerbate the effect on other respiratory symptoms. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Protocols ### Funding Statement This study was funded by the Department of Health, State Government of Victoria, though it represents the views of the authors and not the Department. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Monash University Human Research Ethics Committee (MUHREC) of Monash University gave ethical approval for this work as part of the Hazelwood Adult Survey & Health Record Linkage Study (Project ID: 25680; previously CF15/872 - 2015000389 and 6066) I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are confidential survey responses and therefore cannot be shared. However, we have provided a link to a public repository on which we have archived our cleaning and analytical code.