Disinfection efficacy and safety of 222-nm ultraviolet C compared with 254-nm ultraviolet C: systematic review and meta-analysis

Some studies have indicated that disinfection with 222-nm ultraviolet C (UVC) is more effective than that with 254-nm UVC; however, other studies have reported the opposite. Moreover, additional studies have reported that 222-nm UVC exposure is safe for the skin and eyes. This study aimed to identify and quantitatively synthesize all studies evaluating the disinfection efficacy and safety of 222-nm UVC compared with 254-nm UVC. We conducted a systematic review and meta-analysis. Web of Science, SCOPUS, Medline, Ovid Embase, and the Cochrane Library were searched through November 2024 for studies that evaluated the disinfection efficacy and safety of 222-nm UVC compared with 254-nm UVC. We identified 25 eligible publications including 15 publications providing data only on the efficacy, seven only on the safety, and the remaining three on both efficacy and safety. The pooled odds ratio for studies comparing the efficacy of 222-nm UVC with that of 254-nm UVC was 1.382 (95% CI: 1.153–1.656, N = 18 publications with 87 studies), indicating that 222-nm UVC is more effective for disinfection. The pooled risk difference for studies evaluating the safety of 222-nm UVC radiation was -0.211 (95% CI: -0.245, -0.177; N = 10 publications with 29 studies), which indicates that the proportion of normal cells producing cyclobutane pyrimidine dimers via 222-nm UVC is 21.1% less than that via 254-nm. Compared with 254-nm UVC, 222-nm UVC not only exhibits comparable or potentially superior efficacy in disinfecting diverse micro-organisms but also causes less DNA damage to the mammalian cells.