Experimental study of the disinfection performance of a 222-nm Far-UVC upper-room system on airborne microorganisms in a full-scale chamber. (15th May 2023)

• Record Type: Journal Article
• Authors: Wang, M.H.; Zhang, H.H.; Chan, C.K.; Lee, P.K.H.; Lai, A.C.K.
• Is Part Of: Building and environment. Volume 236(2023)
• Publication Date: 2023-05-15
• Subjects: 222-nm Far-UVC -- Upper-room germicidal irradiation -- UV susceptibility constants -- Infection risk -- Airborne microorganisms; Buildings -- Environmental engineering -- Periodicals; Building -- Research -- Periodicals; Constructions -- Technique de l'environnement -- Périodiques; Electronic journals; 696
• DOI: 10.1016/j.buildenv.2023.110260
• Languages: English
• ISSNs: 0360-1323

Abstract

Abstract: 222-nm Far-UVC light is an emerging and promising tool for rapidly inactivating airborne pathogens. In this study, we experimentally evaluated the performance of a 222-nm Far-UVC upper-room disinfection system with a 15 W Far-UVC lamp in a full-scale chamber (11.9 m 3 ). One gram-positive bacteria, namely Staphylococcus epidermidis and two gram-negative bacteria, namely Escherichia coli and Salmonella enterica were selected for the experiments. The aerosolized bacteria were injected into the chamber and exposed to 222-nm Far-UVC light. The first-order decay rates of indoor bioaerosols concentration with and without Far-UVC treatment were estimated. According to the results, the 222-nm Far-UVC induced decay rates of three bacteria were 0.0611 ± 0.003, 0.409 ± 0.048, and 0.474 ± 0.015 min −1, respectively. Besides, the UV susceptibility constants ( Z -values) of these three bacteria were estimated as 0.157, 0.974, and 1.18 m 2 /J, respectively. The gram-positive bacteria, S. epidermidis, showed higher resistance to Far-UVC light as compared to the gram-negative bacteria, E. coli and S. enterica . In addition, a case study on airborne SARS-CoV-2 indoor transmission was simulated, and the infection risk of SARS-CoV-2 was compared using the Far-UVC and enhanced ventilation approaches. The results showed that both UV inactivation and ventilation approaches can significantly reduce the infection risk. More importantly, the Far-UVC may be a feasible and sustainable solution for reducing infection risk and improving indoor air quality. Highlights: 222-Far-UVC KrCl lamp was installed in the upper room of a full-scale chamber. 3 bacteria were selected to test the air disinfection performance of the Far-UVC. The Far-UVC inactivated 99% airborne gram-negative bacteria around 10 min. Infection risk of SARS-CoV-2 was evaluated for different engineering strategies. Upper-room Far-UVC disinfects air effectively and is energy efficient.