Health risk assessment of wildfire smoke exposure: a protocol for a systematic review and meta-analysis

Wildfire, driven by climate change, continues to pose significant health, social, economic and environmental challenges in the twenty-first century. Although the association between wildfire smoke exposure and health outcomes has been studied, comprehensive systematic reviews and meta-analyses on the global health risks of wildfire smoke exposure are lacking, and the quality and strength of evidence remain uncertain. Therefore, we aim to undertake a comprehensive systematic review and meta-analysis to assess the health risks associated with wildfire smoke exposure at global, regional and national levels in the context of climate change, evaluate the quality and strength of available evidence and identify evidence gaps for future research.

This review will adhere to the updated Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA-2020) guidelines. PubMed, Scopus and Web of Science will be searched to identify relevant articles. A group of researchers will independently screen the retrieved articles using Covidence, based on the inclusion and exclusion criteria. A narrative synthesis will be performed for the included studies. A random-effects meta-analysis will be performed using R software (version 4.3) to determine the pooled association between wildfire smoke air pollutants and health outcomes. Higgins' I² and Egger's test will be employed to assess heterogeneity and publication bias, respectively. Sensitivity and sub-group analysis will also be performed. Risk of bias will be assessed using the Office of Health Assessment and Translation Risk of Bias Rating Tool for Human Studies. The Grading of Recommendations Assessment, Development and Evaluation guidelines will be used to evaluate the quality of evidence. The strength of evidence will be rated as either sufficient, limited, inadequate, or lacking according to the Navigation Guide Framework.

This systematic review and meta-analysis will explore the health risk associated with wildfire smoke exposure across global, regional and national levels encompassing a range of climate zones. The findings from this meta-analysis will provide updated evidence to guide policy makers and communities in efforts to reduce mortality and morbidity associated with wildfire-related air pollutants. The results will also help healthcare providers and emergency responders in managing the growing health risk of wildfire-related air pollutant smoke exposure.

PROSPERO CRD420250654944.