Effectiveness of gaseous ozone in reducing microbial contamination: evaluation of environmental disinfection in healthcare settings

Abstract Objective: Environmental contamination is a significant factor in the transmission of healthcare-associated infections. This study evaluated the effectiveness of gaseous ozone in reducing microbial contamination within hospital settings, focusing on both air and surfaces. Design: A cross-sectional study conducted in a single healthcare facility. Setting: Two experimental protocols were implemented using the Sany-Plus ozonator: a three-timepoint protocol (3T), which included routine cleaning followed by ozone disinfection, and a two-timepoint protocol (2T), where ozone treatment occurred after patient activity without intermediate cleaning. We conducted active air and surface samplings using RODAC plates. Microbial loads were quantified in terms of colony-forming units (CFU) for both bacteria and molds/yeasts. Data analysis was performed using the Friedman and Wilcoxon tests, applying Bonferroni correction for multiple comparisons. Results: In the 3T protocol, bacterial and fungal contamination on surfaces significantly decreased between patient activity and postcleaning, with P -values of .0024 and .0060, respectively. However, no further reduction was observed after ozone disinfection. Airborne microbial loads did not show any statistically significant changes. In the 2T protocol, there was no significant overall decrease in bacterial contamination ( P = .0766), although fungal contamination did experience a significant reduction ( P = .0058). No changes in air contamination were detected. Conclusions: These findings suggest that routine cleaning is the primary determinant of surface decontamination, while ozone treatment may provide a limited complementary antifungal effect. No significant impact on airborne microorganisms was noted. Therefore, ozone should be regarded as an adjunct to, rather than a replacement for, conventional cleaning and disinfection in healthcare environments.