Anti-microbial effect of filtered 222nm excimer lamps in a hospital waiting area

Abstract

Hospital aquired infections is a considerable challenge for vulnerable patients. Traditional anti-microbial mercury lamps emit light at 254nm and have well established anti-microbial effects. Their use in populated areas is, however, hindered by their carcinogenic properties. This is in contrast to anti-microbial lamps based on krypton chloride (KrCl), demonstrated to have no carcinogenic potential. These lamps emit light with a peak intensity at 222nm and have broad bactericidal and viricidal effects including inactivation of SARS-CoVid-2 in laboratory experiments. Here, we investigate the bactericidal effects of filtered KrCl 222nm excimer lamps (UV222 TM lamps) in an out-patient waiting area at the pulmonology clinic at Aarhus University Hospital. Furniture sufaces were sampled for bacterial load in a single-arm interventional longitudinal study with and without exposure to filtered 222nm UVC-light. Furthermore, bacterial species were identified using MALDI-ToF mass-spectrometry. We found filtered 222nm UVC-light to significantly reduced the number of colony-forming-units. Pathogenic bacteria such as Staphylococcus aureus and Staphylococcus epidermidis were detected only in the non-exposed areas suggesting that these species in particular are highly sensitive to inactivation by 222nm UVC-light. This study demonstrates the potential use of 222nm Far-UVC technology to reduce bacterial load and thus the spread of infectious disease in a hospital setting.