Large-Scale Chamber Tests of In-Room Germicidal Ultraviolet (GUV) Systems: Review and Best Practices

Disease outbreaks, including epidemics and pandemics, can disrupt virtually all aspects of social structure and function. Given the likelihood that additional outbreaks will occur in the future, probably involving airborne pathogens, there is a need to develop and implement strategies to mitigate disease transmission associated with these events. In-room (upper-room and whole-room) germicidal ultraviolet (GUV) systems can play key roles in these mitigation strategies and chamber tests are likely to be important for validation of their performance. At present, no uniform standard exists for conducting large-scale chamber tests or for translating the results of those experiments to application environments. In recognition of these needs, an ad-hoc committee was formed to address these issues. The goals of this effort were to conduct a critical review of the literature related to large-scale tests, to suggest “best practices” for these tests (as possible), and to suggest methods for translation of results from the test environment to the application environment. The review includes a summary of existing standards for large-scale testing. These standards provide recommendations for chamber dimensions, materials of construction, and operating conditions. Challenge agents used in these tests are summarized, including viral (phage), bacterial, and non-microbial agent options and their corresponding methods for culture and analysis. Methods of challenge agent introduction and collection are also summarized. Fluence rate field characterization will play critical roles in interpreting chamber test results and translation to application environments; fluence rate field modeling and measurement methods are reviewed and summarized. The implications of the well-mixed assumption, which is commonly applied, are summarized together with methods that can be used to assess mixing behavior. Basic attributes of health and safety issues related to chamber tests are summarized from the literature and from experience.