Scoping review of indoor air quality indexes: Characterization and applications

Better understanding of indoor air quality (IAQ) and parameters affecting it, can improve the management of indoor environment quality (IEQ), reduce health risks, and enhance the occupant's well-being. The energy divisions, health and economy sectors are highly correlated to the concept of IAQ in terms of air ventilation, public health, and productivity. We performed a worldwide scoping review in accordance with the PRISMA extension (PRISMA-ScR) on IAQ indexes with different definitions and indicators, for various aims and applications (from indoor climate to indoor pollutants; for different indoor environments and ventilation setups). Correspondingly, IAQ-related issues were reviewed, including health effects, energy efficiency, and economic impacts. Information on different IAQ indexes was obtained from 110 studies from 23 countries. The use and type of ventilation systems as well as the duration and location of studies are reviewed. Also, the variability of the studied parameters in the literature were investigated. Finally, a novel detailed scoping classification based on different approaches for IAQ index development is presented for the first time. The "objective" approach, has become prevalent over the "subjective" approach, in design, development, and application of IAQ indexes. In addition, consideration of mechanical and natural ventilation was observed in 57 and 18% of the studies, respectively. This scoping review can aid as a first step, to better understand different expressions of IAQ by mean of an index, and their applications for future research and developments.