Bioterrorism attack within large building using bacterial and viral agents in the form of aerosolized submicron spores may create an unprecedented environmental catastrophe. The filtering facepiece respirator (FFR) can be adopted as the first protection. This study investigated the antimicrobial oxidant’s efficacy in diminishing viability of the aerosolized biological agents after passing through the oxidant treated FFR over a period of time. Three FFRs were N95-P100, Triosyn T5000 and Super High Efficiency Particulate Air (HEPA) Medium (SHM). The N95-P100 was the control, whereas, both the T5000 and SHM contained a layer treated with an antimicrobial oxidant. The MS2 bacteriophage agent was aerosolized, passed through the FFRs, and collected in the hot sealed aerosol bags, which were kept for 0-, 1-, 2-, 5-, and 10-minute of residence time before quenching and consuming filter released iodine by a buffer solution (sodium thiosulfate) in all-glass impingers. The viability (plaque forming unit) of the collected microbial agents was quantitated by plaque assays using Single Agar Layer and Escherichia coli. The experimental results for all FFRs were in good agreement with the reported literature. The viability of biological agents for SHM FFR exponentially dropped from 100% to 46%, 28%, 12% and 4% over the period of residence time from 0 minute to 1, 2, 5 and 10 minutes, respectively, this can be interpreted that the half-life was about a minute. Reduction of the viability for T5000 and N95-P100 were very low in the order of 1.4% and 3%, respectively, for all four residence times. The SHM FFR provided the strongest lethal dose of disinfectant to the pathogens than that of N95-P100 and T5000, which can be adopted as mass prophylaxis against airborne submicron-deadly viruses during environmental catastrophe.
Keywords: Biocidal filter, MS2 virus, Infectivity inactivation, Removal Efficiency, Iodine Oxidant