A simple decontamination approach using hydrogen peroxide vapour for Bacillus anthracis spore inactivation

Aims: To evaluate the use of relatively low levels of hydrogen peroxide vapour (HPV) for the inactivation of Bacillus anthracis spores within an indoor environment. Methods and Results: Laboratory-scale decontamination tests were conducted using bacterial spores of both B. anthracis Ames and Bacillus atrophaeus inoculated onto several types of materials. Pilot-scale tests were also conducted using a larger chamber furnished as an indoor office. Commercial off-the-shelf (COTS) humidifiers filled with aqueous solutions of 3 or 8% hydrogen peroxide (H2O2) were used to generate the HPV inside the mock office. The spores were exposed to HPV for periods ranging from 8 h up to 1 week. Conclusions: Four-to seven-day exposures to low levels of HPV (average air concentrations of approx. 5-10 parts per million) were effective in inactivating B. anthracis spores on multiple materials. The HPV can be generated with COTS humidifiers and household H2O2 solutions. With the exception of one test/material, B. atrophaeus spores were equally or more resistant to HPV inactivation compared to those from B. anthracis Ames. Significance and Impact of the Study: This simple and effective decontamination method is another option that could be widely applied in the event of a B. anthracis spore release.