N95 reprocessing by low temperature sterilization with 59% vaporized hydrogen peroxide during the 2020 COVID-19 pandemic

Abstract

Background: Response to the COVID-19 pandemic by hospital systems has been strained by severe shortages in personal protective equipment (PPE), particularly N95 respirators. Recently, the Centers for Disease Control and Prevention endorsed decontamination strategies to prolong the lifespan of single use respirators. Battelle and Duke University have validated hospital protocols to decontaminate respirators using vaporized hydrogen peroxide (VHP) at 30%-35% concentrations. To prolong our supply of respirators, we evaluated and implemented VHP decontamination at 59% hydrogen peroxide concentration while detailing the effects of this process on the filtration efficiency and quantitative fit of single-use respirators. This study may help other health systems develop local solutions to their N95 mask shortage during this COVID-19 pandemic.

Methods: N95 respirators (3M 8211 FF and 9210 FF) that were treated with 5 and 10 cycles of VHP by the V-PRO maX Low Temperature Sterilization System were evaluated quantitatively for filtration efficiency as well as with quantitative fit testing per Occupational Safety and Health Administration standards. A decontamination protocol was concurrently implemented at our institution. This process involved depositing used masks, reprocessing, and re-distributing treated masks efficiently back to frontline providers. Furthermore, we implemented patient safety officers on COVID-19/person under investigation units to ensure optimized donning/doffing of respirators through frontline provider education.

Results: There were no statistically significant changes in mean filtration efficiency between the control and VHP-treated respirators. Furthermore, both treated and untreated respirators demonstrated fit factors above the minimum pass requirement.

Conclusions: We have successfully demonstrated that N95 respirator decontamination with VHP at 59% hydrogen peroxide can be safely utilized to decontaminate single-use N95 respirators without significant effects on filtration efficiency or quantitative fit testing. With the COVID-19 pandemic and N95 respirator shortage, health systems without access to commercial decontamination processes should investigate the viability of such a process in their facilities.

Keywords: Decontamination; N95 filtering facemask.

Fig 1

Above is a sample template of the log sheet that is completed by the transporter before delivering dirty respirators to the decontamination area.

Fig 2

Above is a sample template of the log sheet provided to each provider that utilizes an N95 that has been decontamination with VHP.

Fig 3

The size distribution of the NaCl particles, shown as a function of aerodynamic diameter (D_p), used to challenge the respirators (Blank control) had a geometric mean of 166 nm and geometric standard deviation of 141, and the amount of particles that penetrated a 3M9210 respirator was very low.

Fig 4

VHP decontamination did not have a significant effect on filtration capacity. Though there was a small drop in the 3M 8211 model treated with 10 cycles, the difference was not significant.

Fig 5

There were no significantly significant differences in filtration efficiency of 3M 9210 respirator models treated with 5 and 10 cycles of VHP compared to the untreated control.