Ozone for Inactivation of Aerosolized Bacteriophages

Because of increasing incidence of virus-containing aerosols, ozone was potentially considered to be a promising method to inactivate airborne viruses. In this investigation, bacteriophages MS2, phi X174, phi 6, and T7 are under evaluation. The effects of ozone concentration, contact time, different capsid architecture of virus and relative humidity (RH) on inactivating airborne viruses by ozone were evaluated in a laboratory test chamber. It was observed that the survival fraction of airborne virus decreased exponentially with increasing ozone dose. Airborne viruses required ozone doses of 0.34 to 1.98 and 0.80 to 4.19 min-mg/m ³ for 90% and 99% inactivation, respectively. For all four tested, the ozone dose for 99% inactivation was 2 times higher than that for 90% inactivation. At airborne phase with a short contact time, viruses with more complex capsid architectures were observed to be less susceptible to ozone inactivation than those with simple ones. For all tested viruses at the same inactivation, the required ozone concentration at 85% RH was lower than that at 55% RH, possibly because the generation of more radicals from ozone reacting with water vapor at the higher RH. In summary, it was concluded that ozone is highly effective for the inactivation of airborne virus.

Acknowledgments

This work was supported by grant NSC 93-2621-Z-002-003- from the National Science Council, Republic of China. Chun-Chieh Tseng was supported by a graduate scholarship from the same grant during part of this research effort.