Compliance with the Verification of Environmental Technologies for Agricultural Production Protocol in Ammonia and Particulate Matter Monitoring in Livestock Farming: Development and Validation of the Adherence VERA Index

Air emissions from livestock farming, particularly ammonia (NH3) and particulate matter (PM2.5 and PM10), constitute a major environmental and occupational health concern. The aim of this work was to assess the compliance with the Verification of Environmental Technologies for Agricultural Production (VERA) protocol in livestock emission monitoring studies and to propose the Adherence VERA Index (AVI) as a novel quantitative tool for standardizing methodological evaluation. A literature search was conducted in PubMed and Scopus, identifying 26 eligible studies published between January 2012 and June 2025. Data were extracted on farm characteristics, analytical methods, environmental variables, and emission outcomes, and evaluated across the five VERA protocol domains. The review revealed substantial methodological heterogeneity and overall suboptimal compliance with the VERA protocol, with frequent deficiencies in the reporting of key parameters such as ventilation rate, sampling strategy, and emission estimation methods. In this context, the AVI, by condensing core VERA requirements into a concise and operational metric, may facilitate protocol uptake and improve reporting compliance compared with the full VERA framework. Notably, several studies reported NH3, PM2.5 and PM10 concentrations exceeding occupational and environmental exposure thresholds, particularly in swine and poultry farms, highlighting critical risks to workers’ health. These findings underscore the need for enhanced standardization, integration of occupational health metrics, and improved air quality monitoring to ensure reliable exposure assessment and to safeguard both environmental and worker health in the livestock sector.