Impact of bushfire smoke on respiratory health

To the Editor: The incidence of bushfires, forest fires and wildfires, is increasing globally. Epidemiology shows that individuals with chronic respiratory diseases are most affected with increased hospitalisations. However, the impacts or safe exposure levels of bushfire smoke are not well known.1 We were recently awarded the Medical Research Future Fund's Bushfire Impact Research grant 2020 and in this project we will address the following questions:

• How does bushfire smoke exposure affect respiratory health?
• How does it exacerbate chronic respiratory diseases and affect different age groups?
• What are the impacts on cells, tissues and molecular pathways?
• How can we target the effects therapeutically?

Bushfire smoke is a complex mix of inspirable particles, volatile organics, aldehydes, carbon monoxide, and particulate matter (PM).2 Although extensive research evaluating the effects of bushfire smoke has not been carried out, studies utilising cigarette smoke or vehicular PM_10−2.5 show that exposure to these insults induces lung inflammation and oxidative stress, and promotes the progression of chronic respiratory diseases.3,4,5 Further, in vitro studies with healthy human fibroblasts and bronchoepithelial cells show that bushfire smoke affects pathways including oxidative stress, barrier function, innate defence, and autophagy.6 Accordingly, we plan to expose mice to the different PM particles from bushfire smoke and will elucidate the acute and prolonged effects on lung inflammation, airway remodelling and lung function. In addition, by using our mouse model of chronic respiratory diseases (chronic obstructive pulmonary disease, asthma) and mice at different ages (pregnant, infant, aged), we will assess the impact of bushfire smoke on predisposition, pathogenesis and progression of chronic respiratory diseases. We will use advanced molecular and multi‐omics (single cell/tissue sequencing, proteomics, epigenetics) technology to elucidate cell and tissue responses. Furthermore, we will define therapeutic avenues for prevention and treatment (antioxidants, metabolic modulators) (Box).

The outcomes of this project will inform the development of safe exposure guidelines and define preventive/treatment measures. Moreover, we will address evidence gaps related to harmful health effects of hazardous bushfire smoke exposure which we hope will aid government and health agencies to design appropriate policies, prevention measures, and treatment strategies to deal with future bushfire smoke events.

Box – Methodology for evaluating the impact of bushfire smoke

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COPD = chronic obstructive pulmonary disease; PM = particulate matter.