Disinfection performance of chlorine dioxide gas at ultra-low concentrations and the decay rules under different environmental factors

Gaseous chlorine dioxide (ClO2) is one of the most promising air disinfectants. In this study, an ultra-low concentration of ClO(2)gas (< 1.2 mg/m(3)) was generated in an office at various levels of humidity and illuminance to investigate the decay law. The disinfection efficiency and metal corrosiveness of ultra-low concentrations of ClO(2)gas were also studied using an experimental chamber. At 48% and 75% humidity, the decay rate constants of ClO(2)gas were 0.0034 min(-1)and 0.0036 min(-1), respectively. The rate of decline of the ClO(2)concentration increased as the humidity of the environment increased. The decay rate constant of ClO(2)gas at an illuminance of 76 lux and 3429 lux was 0.0034 min(-1)and 0.00427 min(-1), respectively; hence, the decay rate increased with increased illumination. At a humidity of 72% and illuminance of 2112 lux, the decay rate constant reached 0.00880 min(-1). The effects of humidity and illuminance on the attenuation of the ClO(2)concentration were strongly synergistic. When the gas concentration was maintained below 0.9 mg/m(3), the disinfection rate of ClO(2)on bacteria (P. aeruginosa, V. mimicusandS. aureus) exceeded 99.9%; thus, ClO(2)gas exhibited a high disinfection efficiency. In addition, there was no corrosion to various metals by ClO(2)under the same conditions. Consequently, gaseous ClO(2)at ultra-low concentrations has a high sterilization efficiency and is non-corrosive to metals. Implications Humidity and illuminance can influence decay laws of extremely low concentration ClO(2)gas. The gaseous ClO(2)at ultra-low concentrations has a high sterilisation efficiency and is non-corrosive to metals.