Enhanced sterilization efficacy using UV-activated humid ozone

Abstract The sterilization efficacy of the ultraviolet (UV) activated humid ozone (O 3 ) method was systematically investigated under controlled conditions of UV irradiation, ozone generation, and humidity. This method utilizes the synergistic effects of UV light at 254 nm, ozone, and water vapor to produce reactive oxygen species (ROS), which contribute to microbial inactivation. While ozone alone produced a moderate oxidative environment indicated by qualitative colorimetric chemical indicators complete sterilization, validated using biological indicators containing Bacillus atrophaeus spores (8 × 10 6 CFU per carrier), was achieved only under the combined presence of UV light, ozone, and humidity. UV and vaporized water alone failed to sterilize, confirming ozone’s essential role in initiating the ROS cascade. While this study qualitatively demonstrated the presence of ROS, the specific contributions of individual species such as OH radicals and H 2 O 2 remain to be quantified. Although direct ROS quantification was not performed, qualitative analysis using high-sensitivity colorimetric chemical indicators enabled reliable comparisons between treatment conditions. These findings establish ozone as a critical enabler in low-temperature ROS-based sterilization and demonstrate that the UV-activated humid ozone method offers a rapid, non-thermal, and environmentally sustainable alternative suitable for clinical, industrial, and biotechnological applications.