Interventions for reducing exposure to air pollution from landscape fires in a changing environment: A systematic review

Emissions from more frequent and prolonged landscape fires (wildfires, risk reduction fires, agricultural burning) can expose populations to high levels of air pollution and exacerbate a range of health conditions. This systematic review aims to map, evaluate, and synthesise the scientific literature reporting interventions that can reduce exposure to landscape fire smoke (LFS). Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we searched PubMed, Scopus and Web of Science and reviewed relevant literature published until March 2024. Thirty-three studies from four countries met the eligibility criteria. Of the interventions evaluated, air filtration was the most frequently reported, and included use of portable air cleaners (PACs) with high efficiency particulate air (HEPA) filters, ventilation systems with standard and upgraded filters, and low-cost fan filter units (FFU). The effectiveness of PACs for fine particulate matter (PM 2.5) reduction ranged between 54 %-92 %. In naturally ventilated residences, concentrations of PM 2.5 were 0-44 % lower indoors, and depended on the duration of LFS, building operation, and permeability. Mechanical ventilation with minimum efficiency reporting value (MERV) 5/8 filters in buildings reduced LFS PM 2.5 levels by 18-58 %; however, use of higher rated filters (e.g., MERV 12/13) achieved reductions of up to 87 %. Communication interventions, including smartphone apps and alerts/messages from various media sources (e.g., radio, television, internet) had mixed results; nevertheless, inclusion of spirometry and asthma control surveys during app use could improve health outcomes for vulnerable groups. The efficacy of facemasks (N95/P2) was up to 94 % for single pass PM 2.5 removal, although they were relatively underutilised. Clean air shelters in public buildings can potentially provide a place for exposure reduction and social support, but have not been sufficiently tested during LFS events. Further research is needed on the effectiveness of interventions during prolonged smoke events, and in low- and middle-income countries.