Synergistic Disinfection by 222 nm Far-UVC and Negative Air Ions of Airborne Bacteria and the Induced Oxidative Stress Responses: A Bioaerosol Chamber Study

The understanding of the mechanisms of synergistic bioaerosol disinfection using 222 nm far-UVC and negative air ions is limited. In this study, we employed a fabricated aerosol chamber to investigate the synergistic disinfection effects of these two technologies and their impact on oxidative stress responses in airborne Staphylococcus epidermidis, Salmonella enterica, and Escherichia coli. We measured the log reduction in airborne survival of bacteria, lipid peroxidation, and the activities of antioxidant enzymes and total antioxidants. The results show that bacterial inactivation by the simultaneous operation of both technologies was significantly greater than the sum of the inactivation values by individual treatments, demonstrating a synergistic disinfection effect. The Pearson correlation coefficient indicates a strong correlation between airborne bacterial survival and lipid peroxidation (r ≥ 0.83). Furthermore, 222 nm far-UVC was found to be able to inactivate the antioxidant defense in airborne bacteria. Our results together suggest that the simultaneous operation of 222 nm far-UVC and negative air ions induces oxidative stress while deactivating antioxidant defense, contributing to the observed synergistic disinfection effect. Findings from the current study contribute to the mechanistic understanding of the synergistic effect by 222 nm far-UVC and negative air ions in bioaerosol disinfection, offering a new research opportunity for system design in high-efficiency air disinfection. © 2024 American Chemical Society.