A Systematic Scoping Review of the Impact of Far-UVC on Pathogen Reduction in Indoor Built Environments

Far-UVC, or far-ultraviolet C, is a form of germicidal ultraviolet light that often operates at 222 nm with emerging applications for continuous disinfection in occupied indoor environments. Laboratory studies have provided strong evidence supporting far-UVC’s pathogen-inactivation capabilities, but additional real-world investigation is needed. As such, this review aims to consolidate evaluations of far-UVC disinfection efficacy in indoor built environments through a systematic scoping review. A protocol summarizing the outcomes of interest, search strategy, and inclusion/exclusion criteria was first created and used to guide searches of PubMed, Scopus, and Embase for studies evaluating the efficacy of far-UVC disinfection in indoor built-environment settings. Six studies met the inclusion criteria, and data on study design, device characteristics, microbial targets, and efficacy outcomes were extracted and synthesized. Most (n=5, 83%) were longitudinal pre/post experiments that measured disinfection efficacy at various intervals of consistent far-UVC exposure, ranging in duration from hours to months, often using inoculated surfaces, artificial carriers, and naturally occurring contamination. Only one study collected pre- and post-exposure measurements of microbial contamination on contaminated surfaces following short-term far-UVC exposure. Across studies, far-UVC produced measurable reductions in microbial contamination on surfaces and in air samples compared with controls and standard cleaning protocols. Still, efficacy and statistical significance varied by organism, surface type, and dose delivered. Methodological reporting on irradiation dose, microbial sampling, and recovery methods was poor. Conclusions and evidence from included studies indicate an overall favorable opinion of far-UVC efficacy for disinfecting public indoor environments, but further investigation is required regarding the feasibility of device installation and the efficacy of far-UVC disinfection in consistently occupied spaces.