A systematic global review of fixed air quality monitoring stations: Spatial distribution, typologies, measured pollutants, technologies, regulatory standards, and research gaps

Air pollution is a global threat that significantly affects human and environmental health, and fixed Air Quality Monitoring Stations (AQMS), play a pivotal role in assessing ambient air conditions and informing regulatory policies. This systematic review provides a global overview of fixed air pollution monitoring stations, focusing on the geographical distribution of stations, classification, pollutants measured at each station, measurement techniques for each pollutant, monitoring frameworks, and implementation challenges. A comprehensive search of PubMed, Scopus, Web of Science, and grey literature identified 17 eligible studies covering diverse regions across Europe, Asia, Africa, and the Americas. This assessment uncovers Critical disparities in air quality monitoring architectures, revealing: (i) non-uniform station distribution patterns, (ii) technology adoption gaps, and (iii) pollutant coverage imbalances that collectively hinder comparable air quality assessments across regions and While high-income countries operate and maintain sophisticated networks and advanced, reference-grade analyzers, low- and middle-income countries use low-resolution, short-term, or inexpensive sensors that provide limited and fragmented data. This review, synthesizing global evidence, highlights the urgent need for equitable, reliable, and policy-driven monitoring systems worldwide.