Assessment of the air disinfection effect of low-concentration ozone in a closed environment

Ozone, a prevalent pollutant in enclosed spaces, can pose health risks even at low levels. Despite its widespread use for disinfection, the efficacy in neutralizing airborne pathogens in confined settings remains uncertain. A study was conducted to investigate the disinfection capabilities of low-concentration ozone (several dozen parts per billion, ppb), within an isolation ward. Serratia marcescens and phi-X174 were used as tracer bioaerosols. The study examined two scenarios of applying low-concentration ozone in closed environments: direct introduction of low-concentration ozone into the ward and comparison of air disinfection effects of ozone-producing and non-ozone-producing UVC lamps. The UVC lamps chosen for this study were of 185 nm and 254 nm, which cannot coexist with humans when turned on. The results revealed that ozone concentrations below 60 ppb did not significantly impact air disinfection regarding Serratia marcescens and there was no noteworthy difference in effectiveness between the two types of UVC lamps for both Serratia marcescens and phi-X174. However, using UVC lamp resulted in a significantly higher air disinfection effect compared to the absence of a UVC lamp. For Serratia marcescens, the inclusion of ozone-producing and non-ozone producing UVC lamps (k = 49.8 & PLUSMN; 9.2 h-1, 52.9 & PLUSMN; 8.6 h-1, mean & PLUSMN; SD) significantly enhanced the decay rate by 29.6 h-1 and 32.7 h-1 respectively, compared with the absence of UVC lamps (k = 20.2 & PLUSMN; 2.3 h-1, mean & PLUSMN; SD). These findings highlight the limited potential of low-concentration ozone for air disinfection and emphasize the need for cautious utilization in enclosed environments.