Mapping the knowledge pattern of ultraviolet germicidal irradiation for cleaner indoor air through the lens of bibliometrics

Due to the global outbreak of infectious diseases over the years, airborne pathogen removal from the indoor environment has become a critical issue. Ultraviolet germicidal irradiation (UVGI) has been adopted as a strategic solution, and its implementation shows the enormous potential of inactivating airborne infectious pathogens. Despite extensive research, some critical research areas or gaps remain unidentified, while at the same time, few studies highlight the knowledge trend for UVGI air disinfection research necessary to guide investigators and practitioners. The purpose of this paper is to provide a thorough and objective analysis of UVGI research areas using bibliometric analysis. The available international standard known as the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) was followed for conducting this review. A comprehensive search covering the publication year up to December 2021 using Web of Science (WoS), Scopus, and PubMed databases was conducted. Also, the selection of studies, extraction of data, and assessments of risk of bias were also carried out. The characteristics and results of selected studies in evidence graphs, pie charts, network maps, and tables were presented and discussed. A total of 210 UVGI air disinfection-related publications were identified and reviewed. Based on the keyword co-occurrence analysis, document and direct citation analysis, 112 research keywords (see Table A1), and 6 core research journals were identified. Further, the results show that 3 countries and 7 organizational collaborators are at the centre of UVGI research. Based on the clustering analysis and comprehensive analysis of the findings, the research domain was developed, which grouped UVGI research into four themes. These findings are highly important for the advancement of UVGI. This paper provides a significant contribution by showing the knowledge pattern needed to facilitate further research and applications for both academia and industry stakeholders to improve indoor air quality.