GYAN DEEP SHARMA AND SIDDHARTHA SHUKLA
Abstract
Indoor Air Quality (IAQ) greatly determines human health, comfortable conditions, and occupant productivity in built environments. However, quantifying IAQ with accuracy is difficult owing to diversity in pollutant sources, variations in indoor activities, and diversity in monitoring protocols. In this review, IAQ differences between commercial and residential buildings with a focus on carbon dioxide (CO2) levels as an indicator of ventilation effectiveness and occupant exposure are explored. Studies comparing CO2 concentrations are reported within a range of 880.4 ppm up to a whopping 2,900 ppm in various global studies spanning between 2020 and 2025. Notably, commercial buildings are found to hold high concentrations owing to high occupant densities, centralized air handling, and emissions from equipment, while residential environments are influenced based on cooking activity, design, and ventilation strategies. Long-term CO2 concentrations beyond 1,000 ppm are blamed for cognitive impairment, discomfort, and adverse respiratory consequences. In this research, IAQ-based building standards are promoted with a particular push in maintaining CO2 concentrations within lower than 1,000 ppm. In our review, the importance in conducting longitudinal studies in tracking chronic exposure consequences is highlighted, with a request for scalable, technology-based solutions in safeguarding occupant health in different building typologies.