Long‐term effects of extreme smoke exposure on COVID‐19: A cohort study

Abstract

BackgroundIn 2014, the Hazelwood coalmine fire shrouded the regional Australian town of Morwell in smoke and ash for 6 weeks. One of the fire's by‐products, PM2.5, is associated with an increased risk of COVID‐19 and severe disease. However, it is unclear whether the effect persisted for years after exposure. In this study, we surveyed a cohort established prior to the pandemic to determine whether PM2.5 from the coalmine fire increased long‐term vulnerability to COVID‐19 and severe disease.MethodsFrom August to December 2022, 612 members of the Hazelwood Health Study's adult cohort, established in 2016/17, participated in a follow‐up survey that included standardized items to capture COVID‐19 cases, as well as questions about hospitalization and vaccinations. Associations were evaluated in crude and adjusted logistic regression models.ResultsA total of 268 (44%) participants self‐reported or met symptom criteria for having had COVID‐19 at least once. All models found a positive association, with odds of COVID‐19 increasing by between 4% and 30% for a 10 μg/m3 increase in coalmine fire‐related PM2.5 exposure. However, the association was significant in only 2 of the 18 models. There were insufficient hospitalizations to examine severity (n = 7; 1%).ConclusionThe findings are inconclusive on the effect of coalmine fire‐related PM2.5 exposure on long‐term vulnerability to COVID‐19. Given the positive association that was robust to modelling variations as well as evidence for a causal mechanism, it would be prudent to treat PM2.5 from fire events as a long‐term risk factor until more evidence accumulates.

Lung function may recover after coal mine fire smoke exposure: a longitudinal cohort study

“…We previously utilised PM 2•5 data from the Environment Protection Authority (EPA) of Victoria to evaluate possible exposure variations between Morwell and Sale, as a result of this event. While ambient PM 2•5 has the potential to confound associations, we found little difference in annual mean ambient PM 2•5 between Morwell (7.9 μg/m 3 ) and Sale (7.6 μg/m 3 ) from 2009 to 2022 [24,25] which included the bushfire period.…”

“…[42] With a second round of data collection, we were able to conduct a longitudinal analysis of the impact of PM However, examination of ambient PM 2•5 levels between 2009 and 2022, including during the 2019-20 bushfires, suggested no evidence of different exposures between the two towns of Morwell and Sale. [24] Finally, the analysis conducted multiple comparisons and may contain chance findings.…”

This time the canary is the coal mine

“…The team has since looked at the impact of this event on several conditions, for example, asthma, cancer and mental health 4–6 . In a recent publication in Respirology, the authors present their findings of a questionnaire‐based study, which was designed to examine the effect of this extreme exposure on Covid‐19, although there was a gap of many years between the event and the pandemic 7 . Residents form the town of Morwell (heavily exposed) were compared with residents from the town of Sale (not exposed).…”