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

SummaryBackgroundHospital aquired infections is a considerable challenge for vulnerable patients. Ultraviolet light based on the excitation of mercury emit light at 254nm and has well established antimicrobial effects but the use hereof in populated areas is hindered by the carcinogenic properties of 254nm. This is in contrast to the recently developed excimer lamps based on krypton chloride (KrCl). These lamps emit light with a peak intensity at a wavelength of 222nm and have recently been demonstrated to have broad bactericidal and viricidal effects including efficient inactivation of SARS-CoV2. It is, however, unclear how efficiently 222nm lamps perform in a real-life setting such as a hospital waiting area. In this study we aimed to assess the antimicrobial efficacy of filtered 222nm excimer lamps in a real-world setting at an out-patient pulmonology clinic.MethodsFiltered KrCl 222nm excimer lamps (UV222 lamps) were installed in a densely populated waiting room at the out-patient waiting area at Department of Respiratory Diseases and Allergy at Aarhus University Hospital, Aarhus, Denmark. Furniture sufaces were sampled and analyzed 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.FindingsThe exposure to filtered 222nm UVC-light significantly reduced the number of colony-forming-units, and patches with high desity of bacteria. Pathogenic bacteria such as Staphylococcus Aureus and Staphylococcus Epidermidis were detected only in the non-exposed areas suggesting that these species are highly sensitive to inactivation by 222nm UVC-light.ConclusionFiltered 222nm UVC-light is highly anti-microbial in a real-world clinical setting reducing bacterial load and eradicating clinically relevant bacteria species. Filtered 222nm UVC-light has the potential to become an important part of current and future anti-microbial prevention in the clinic.

SARS-CoV-2 disinfection in aqueous solution by UV222 from a krypton chlorine excilamp

ABSTRACTThere is an urgent need for evidence-based development and implementation of engineering controls to reduce transmission of SARS-CoV-2, the etiological agent of COVID-19. Ultraviolet (UV) light can inactivate coronaviruses, but the practicality of UV light as an engineering control in public spaces is limited by the hazardous nature of conventional UV lamps, which are Mercury (Hg)-based and emit a peak wavelength (254 nm) that penetrates human skin and is carcinogenic. Recent advances in the development and production of Krypton Chlorine (KrCl) excimer lamps hold promise in this regard, as these emit a shorter peak wavelength (222 nm) and are recently being produced to filter out emission above 240 nm. However, the disinfection kinetics of KrCl UV excimer lamps against SARS-CoV-2 are unknown. Here we provide the first dose response report for SARS-CoV-2 exposed to a commercial filtered KrCl excimer light source emitting primarily 222 nm UV light (UV222), using multiple assays of SARS-CoV-2 viability. Plaque infectivity assays demonstrate the pseudo-first order rate constant of SARS-CoV-2 reduction of infectivity to host cells to be 0.64 cm2/mJ (R2 = 0.95), which equates to a D90 (dose for 1 log10 or 90% inactivation) of 1.6 mJ/cm2. Through RT-qPCR assays targeting the nucleocapsid (N) gene with a short (<100 bp) and long (∼1000 bp) amplicon in samples immediately after UV222 exposure, the reduction of ability to amplify indicated an approximately 10% contribution of N gene damage to disinfection kinetics. Through ELISA assay targeting the N protein in samples immediately after UV222 exposure, we found no dose response of the ability to damage the N protein. In both qPCR assays and the ELISA assay of viral outgrowth supernatants collected 3 days after incubation of untreated and UV222 treated SARS-CoV-2, molecular damage rate constants were similar, but lower than disinfection rate constants. These data provide quantitative evidence for UV222 doses required to disinfect SARS-CoV-2 in aqueous solution that can be used to develop further understanding of disinfection in air, and to inform decisions about implementing UV222 for preventing transmission of COVID19.ABSTRACT ART / TOC GRAPHIC

Experience of using an excimer lamp equipped with UVB dose control system in dermatology

Intermediate ultraviolet (UVB) therapy is considered a relatively safe method of treating skin diseases with an autoimmune component in development compared to medical drug methods, including PUVA therapy. This is due to the small depth of penetration of the rays of this wavelength range into skin, which provides a purely local effect on the human body. Excimer lamps are an alternative to the expensive excimer laser for phototherapy of psoriasis or vitiligo. However, for effective phototherapy using UVB lamps, the distance from an emitter to a patient’s skin must be considered. In this paper, we report on treatment of patients using an excimer lamp, the control unit of which is equipped with an optical system for controlling of ultraviolet radiation dose, which allows automatically calculating the time for a set UVB dose. The article describes the results of phototherapy using an excimer lamp of several cases of psoriasis, vitiligo and other forms of dermatitis with a good therapeutic and cosmetic effect. When using an excimer lamp, not a single case of exacerbation of dermatological diseases was established.

A laboratory-scale annular continuous flow reactor for UV photochemistry using excimer lamps for discrete wavelength excitation and its use in a wavelength study of a photodecarboxlyative cyclisation

A novel annular flow reactor for UV photochemistry.