Analysis of SteraMist ionized hydrogen peroxide technology as a method for sterilizing N95 respirators and other personal protective equipment

The COVID-19 pandemic has led to widespread shortages of personal protective equipment (PPE) for healthcare workers, including filtering facepiece respirators (FFRs) such as N95 masks. These masks are normally intended for single use, but their sterilization and subsequent reuse could substantially mitigate a world-wide shortage. In this study, we investigate PPE sterilization using ionized hydrogen peroxide (iHP), generated by SteraMist® equipment (TOMI; Frederick, MD), in a sealed environment chamber installed in the animal facility of an academic medical center. Following one to five sterilization cycles, five N95 mask models from three manufacturers were evaluated using three criteria: efficiency of iHP in sterilization (measured with bacterial spores in standard biological indicator assemblies), ability of sterilized masks to efficiently filter particles down to 0.3μm, and a quantitative fit test. Filtration efficiency was measured using ambient particulate matter at a university lab and an aerosolized NaCl challenge at a National Institute for Occupational Safety and Health (NIOSH) pre-certification laboratory. The data demonstrate that N95 masks sterilized using SteraMist iHP technology retain function up to five cycles, the maximum number tested. Some but not all PPE could also be sterilized in the same manner, and pre-treatment with a handheld iHP generator was required for semi-enclosed surfaces such as respirator hoses. A typical environment chamber with a volume of ~80 m3 can treat ~7000 masks per day, and as well as other items of PPE, making this an effective approach for a busy medical center.