{"title":"Experimental investigation comparing Far-UVC (222nm) and UVC (254nm) for inactivation of bacteria on hard and fabric surfaces","authors":"X.W. Su , B.R. Chen , W.S. Li , A.C.K. Lai","doi":"10.1016/j.buildenv.2024.112324","DOIUrl":null,"url":null,"abstract":"<div><div>Bacterial infections are very common and can result from contact with contaminated surfaces in indoor environments. Far-UVC irradiation (222 nm) is now being explored as an emerging solution for disinfecting surfaces. We conducted a comparison of the surface disinfection efficacy between two UVC sources: a krypton-chloride Far-UVC lamp at 222 nm and a traditional 254 nm mercury-type UVC lamp. We evaluated the bactericidal effects of UVC irradiation at ten doses from 0.5 mJ/cm<sup>2</sup> to 37.6 mJ/cm<sup>2</sup> for both wavelengths on methicillin-resistant <em>Staphylococcus aureus</em> (MRSA), <em>Klebsiella pneumoniae</em> (<em>K. pneumoniae</em>), and <em>Pseudomonas aeruginosa</em> (<em>P. aeruginosa</em>), on two commonly encountered hard surfaces: plastic and stainless steel, and MRSA was tested for cotton fabric. The results indicated that for hard surfaces two decay stages were identified as the UVC dose increased. In the first stage, the three bacteria exhibited rapid inactivation. However, as the irradiation approached 5 mJ/cm<sup>2</sup>, the decay rate slowed down, indicating the occurrence of a second stage. Our study highlights the importance of cautious calculation when using a specific stage to estimate UVC dose for disinfection purposes. Specifically, we found that achieving 99.9% disinfection efficacy of MRSA on a plastic surface requires an actual Far-UVC dose of 32.80 mJ/cm². In contrast, if only the first stage decay rate constant is considered, the dose would be greatly underestimated (8.368 mJ/cm²). This shows the large discrepancy between these two estimation approaches. The Far-UVC irradiation results on cotton fabric surfaces did not exhibit a second stage, which may relate to the fabric structure.</div></div>","PeriodicalId":9273,"journal":{"name":"Building and Environment","volume":"267 ","pages":"Article 112324"},"PeriodicalIF":7.1000,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Building and Environment","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0360132324011661","RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CONSTRUCTION & BUILDING TECHNOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Bacterial infections are very common and can result from contact with contaminated surfaces in indoor environments. Far-UVC irradiation (222 nm) is now being explored as an emerging solution for disinfecting surfaces. We conducted a comparison of the surface disinfection efficacy between two UVC sources: a krypton-chloride Far-UVC lamp at 222 nm and a traditional 254 nm mercury-type UVC lamp. We evaluated the bactericidal effects of UVC irradiation at ten doses from 0.5 mJ/cm2 to 37.6 mJ/cm2 for both wavelengths on methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae (K. pneumoniae), and Pseudomonas aeruginosa (P. aeruginosa), on two commonly encountered hard surfaces: plastic and stainless steel, and MRSA was tested for cotton fabric. The results indicated that for hard surfaces two decay stages were identified as the UVC dose increased. In the first stage, the three bacteria exhibited rapid inactivation. However, as the irradiation approached 5 mJ/cm2, the decay rate slowed down, indicating the occurrence of a second stage. Our study highlights the importance of cautious calculation when using a specific stage to estimate UVC dose for disinfection purposes. Specifically, we found that achieving 99.9% disinfection efficacy of MRSA on a plastic surface requires an actual Far-UVC dose of 32.80 mJ/cm². In contrast, if only the first stage decay rate constant is considered, the dose would be greatly underestimated (8.368 mJ/cm²). This shows the large discrepancy between these two estimation approaches. The Far-UVC irradiation results on cotton fabric surfaces did not exhibit a second stage, which may relate to the fabric structure.
期刊介绍:
Building and Environment, an international journal, is dedicated to publishing original research papers, comprehensive review articles, editorials, and short communications in the fields of building science, urban physics, and human interaction with the indoor and outdoor built environment. The journal emphasizes innovative technologies and knowledge verified through measurement and analysis. It covers environmental performance across various spatial scales, from cities and communities to buildings and systems, fostering collaborative, multi-disciplinary research with broader significance.