Protocol: Chemical indoor air quality in agri-food workplaces: a systematic review of measured concentrations, reference values and emerging contaminants

Protocol of a systematic review (v1.0, approved by all authors on 2 November 2026, before the final database searches). The review will synthesise measured airborne concentrations of chemical contaminants, both established (gases, particulate matter, volatile and semi-volatile organic compounds, pesticides) and emerging (e.g. microplastics, PFAS), in three agri-food workplaces: livestock and poultry buildings, greenhouses and food-processing plants. Concentrations will be compared with WHO air quality guideline values and with occupational exposure limits (EU, national, ACGIH, NIOSH, OSHA). Design: PRISMA 2020 and PRISMA-S; synthesis without meta-analysis (SWiM). Databases: Scopus, Web of Science and PubMed, from 2015 to 2026, English, articles and reviews, plus citation searching and seed articles. Screening and data extraction by two independent reviewers (F. Carriera, P. Avino), with a third reviewer (G. Settimo) for disagreements. Risk of bias: JBI checklist for analytical cross-sectional studies, adapted with exposure-assessment items. The protocol is not registered in PROSPERO because the review concerns measured concentrations and not health outcomes. Files: protocol (PDF) and the search strings. SHA-256 of Review_Protocol.pdf: d3651d3267dc1ce9a5749de05afc9e016fcd06e92bd9d2c4a2c9eeb6d68d4c1c; of search_strings.txt: 6852efd42eb43d8154535a2d9ed75b3751e242edfa59e1e424cf966aa0170aaa.