ABSTRACT
Purpose: UVC radiation has been proven to kill known pathogens and recent years have seen increased adoption of UVC disinfection technology in healthcare settings in an effort to limit the spread of COVID-19 and other common hospital-acquired infections. European Council Directive 2006/25/EC outlines the maximum permissible exposure (MPE) levels for workers due to artificial optical radiation. Knowing the output of a UVC disinfection system allows us to better quantify the risks however this quantitative information is not readily available to the user for some systems. The purpose of this study was to measure the output of a UVC disinfection system used in a hospital environment using a light meter calibrated for the UVC range. Material(s) and Method(s): The THOR UVC disinfection system (Finsen Technologies Ltd, UK) was used for this study. This system uses 90- watt TUV PL-L mercury lamps (Philips Lighting, UK) which emit UVC light at 254nm. It features 24 bulbs around a central column, and the system is controlled remotely via a tablet interface. An ILT2400 light meter (International Light Technologies, USA) calibrated for the 254nm UVC range was mounted on a tripod. The output was measured under different conditions to determine repeatability, consistency, and variation with height, distance, orientation, and exposure time. Unless stated otherwise the measurements were taken at a distance of 1m and a height of 1.5m. The test area chosen was representative of the maximum size of a patient room with an area of 31m2. Result(s): The mean maximum output of the system was 2.2+/-0.1 mW/ cm2. This was found to be consistent over a period of 25 minutes. These results were used to calculate the time to reach the MPE (T[MPE]). The output at a tower orientation of 0degree and 180degree was found to be 22% higher than those at orientations of 90degree and 270degree. Conclusion(s): Using these quantitative results, it was possible to determine the maximum permissible exposure time for the UVC radiation emitted from this system. The observed variations in system output due to contributions of scattered radiation, system orientation, and height may have implications for the degree of disinfection achieved. The T[MPE] of 2.6 seconds based on these measurements was 20% lower than the value estimated. The orientation of the system was shown to impact the T[MPE]. These results highlight that a multidisciplinary approach which includes Medical Physics should be taken when introducing these systems to a hospital environment. Note: changed to ePoster after submission.Copyright © 2023 Southern Society for Clinical Investigation.