Ventilation and filtration strategies to reduce respiratory infections in schools: a scoping review

Objective: This scoping review examines evidence on ventilation and filtration strategies in schools and their association with respiratory infection incidence and proxy indicators such as CO2, particulate levels, and absenteeism. Methods: Following PRISMA-ScR guidelines, we searched PubMed, Embase, and Web of Science (19 March 2025) for studies published between 2020 and 2025 in English, French, or Italian. Eligible designs included interventional, observational, and modelling studies, as well as reviews. Screening and data extraction were performed using Rayyan, and similar publications were verified with LiteRev. Results: Sixty-two studies met inclusion criteria. Mechanical ventilation, especially with high-efficiency filtration, was associated with lower CO2, fewer airborne particles, and reduced infection incidence or absenteeism. Natural ventilation showed variable effectiveness influenced by climate and window use. Hybrid systems and multilayered approaches provided the greatest reductions in estimated infection risk. Conclusion: Ventilation and filtration strategies reduce respiratory infection risk in schools. Mechanical and hybrid systems perform more reliably than natural ventilation. Further research should address feasibility, safety, sustainability, and implementation in low-resource settings.