INDOOR AIR QUALITY IN CLASSROOM ENVIRONMENTS: A SCOPING REVIEW
Keywords:
Indoor Air Quality, Classroom Environment, Occupancy Effects, CO₂ Monitoring, Particulate Matter, IoT-Based MonitoringAbstract
This scoping review synthesises 33 peer-reviewed studies (2012–2026) on classroom indoor air quality (IAQ), identified through OpenAlex and screened using PRISMA-ScR. The review addresses IAQ parameters, occupancy effects, monitoring technologies, and research gaps. CO₂ was the most consistently monitored parameter; exceedances above 1000 ppm were documented in 19 of 28 empirical studies, with peaks reaching 2200 ppm in naturally ventilated classrooms. PM₂.₅ and PM₁₀ concentrations increased 2.3–3.4-fold during occupied periods. IoT-based monitoring has improved temporal resolution substantially, and machine learning now predicts threshold exceedances with >85% accuracy. Six research gaps were identified: single-parameter monitoring dominance, absence of controlled dual-room comparative studies, underreporting of exposure duration, lack of simultaneous occupancy–ventilation experimental arms, absence of real-time alerts, and underrepresentation of South Asian environments. These gaps inform the design of a dual-node IoT system deployed in academic staff rooms in Bellary, Karnataka, India.
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