Safety Evaluation of Air Cleaner Technologies in the Building Sector

Indoor air quality (IAQ) plays a central role in human health, comfort, and productivity, particularly because people spend the majority of their time indoors. A growing body of research links indoor pollutants— including fine particulate matter (PM2.5), volatile organic compounds (VOCs), and bioaerosols to respiratory illness, cardiovascular stress, cognitive impairment, and reduced performance. In response to these risks, numerous air-cleaning technologies have been adopted in residential, commercial, and institutional buildings, including high-efficiency particulate air (HEPA) filtration, photocatalytic oxidation (PCO), plasma air cleaners, activated carbon adsorption, ultraviolet germicidal irradiation (UVGI), electrostatic precipitation, and ionization systems. Most evaluations of these technologies focus primarily on pollutant removal efficiency or clean air delivery rate, while broader considerations such as byproduct formation, operational requirements, and lifecycle costs receive less attention. Evidence from recent studies suggests that some air-cleaning technologies may generate secondary pollutants, including ozone or reactive chemical species, raising concerns that certain solutions intended to improve air quality may also introduce additional health risks. To examine this issue systematically, this study develops a multi-criteria decision-making (MCDM) framework for evaluating indoor air-cleaning technologies. The framework integrates four principal dimensions: pollutant removal performance, byproduct formation risk, operational requirements, and economic cost. Twelve quantitative criteria describing pollutant removal efficiency, potential hazardous emissions, energy use, maintenance demands, and lifecycle cost were normalized and weighted using the Analytic Hierarchy Process (AHP). These criteria were combined into a composite indicator, the Health and Safety Performance Index (HSPI), which reflects both pollutant removal benefits and safety penalties associated with byproduct formation. Application of the framework shows that mechanical filtration technologies, particularly HEPA filtration and activated carbon adsorption achieve the highest HSPI scores because they provide effective pollutant removal while producing minimal secondary emissions. In contrast, technologies relying on ionization, ozone generation, or plasma processes generally rank lower due to higher safety penalties and operational trade-offs. These findings provide a structured basis for comparing air-cleaning technologies and support more informed decision-making in indoor air quality management by incorporating a perspective that considers not only effectiveness but also the risk of unintended or hidden adverse effects in the post-pandemic era.