A review of UVC air disinfection for built environments: Inactivation mechanisms, kinetic models, and influencing determinants.

The COVID-19 pandemic has significantly heightened public awareness of air quality and its implications for human health, propelling air sterilization technologies to the forefront research. This Review synthesizes recent progress in ultraviolet C (UVC)-based air disinfection, integrating inactivation mechanisms, irradiance distribution models and microbial inactivation kinetics. We compare major UVC light sources and examine how optical properties, spatial deployment and environmental conditions govern dose delivery and disinfection efficacy. Key physical and biological factors-including wavelength, airflow, humidity and microbial heterogeneity-are discussed in the context of predictive modelling and system optimization. We highlight critical limitations related to safety, penetration depth and energy efficiency, and outline future directions centred on far-UVC technologies, solid-state light sources and intelligent control strategies. Together, this Review provides a conceptual framework for the rational design and safe implementation of UVC air disinfection systems in public and built environments.