Characterization of a novel, low-cost, scalable vaporized hydrogen peroxide system for sterilization of N95 respirators and other COVID-19 related personal protective equipment

Abstract

Due to the virulence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the pathogen responsible for the respiratory disease termed COVID-19, there has been a significant increase in demand for surgical masks and N95 respirators in medical clinics as well as within communities operating during the COVID-19 epidemic. Thus, community members, business owners, and even medical personnel have resorted to alternative methods for sterilizing face coverings and N95 respirators for reuse. While significant work has shown that vaporized hydrogen peroxide (VHP) can be used to sterilize N95 respirators, the cost and installation time for these sterilization systems limit their accessibility. To this end, we have designed and constructed a novel, cost-effective, and scalable VHP system that can be used to sterilize N95 respirators and other face coverings for clinical and community applications. N95 respirators inoculated with P22 bacteriophage showed a greater than 6-log10 reduction in viral load when sterilized in the VHP system for one 60-minute cycle. Further, N95 respirators treated with 20 cycles in this VHP system showed comparable filtration efficiency to untreated N95 respirators in a 50 to 200 nanometer particulate challenge filtration test. While a 23% average increase in water droplet roll-off time was observed for N95 respirators treated with 5 cycles in the sterilization, no breakdown in fluid resistance was detected. These data suggest that our VHP system is effective in sterilizing N95 respirators and other polypropylene masks for reuse. Relating to the present epidemic, deployment of this system reduces the risk of COVID-19 community transmission while conserving monetary resources otherwise spent on the continuous purchase of disposable N95 respirators and other face coverings. In summary, this novel, scientifically validated sterilization system can be easily built at a low cost and implemented in a wide range of settings.

A systematic review of mask disinfection and reuse for SARS-CoV-2 (through July 10, 2020)

“…Overall, 16 studies measured disinfection and durability 12, 15, 19, 20, 22, 27-30, 33, 36, 47, 49, 51, 62, 64 , 16 studies measured only disinfection 13, 18, 23, 24, 31, 38, 40, 41, 43, 44, 48, 56, 63, 65-67 and 26 studies measured only durability 7, 14, 16, 17, 21, 25, 26, 32, 34, 35, 37, 39, 42, 45, 46, 50, 52-55, 57-61, 68 . Thus, 32 studies measured disinfection and 42 measured durability.…”

“…In total, 92 individual mask disinfection tests were conducted across 32 studies 12, 13, 15, 18-20, 22-24, 27-31, 33, 36, 38, 40, 41, 43, 44, 47-49, 51, 56, 62-67 . The masks tested included: 75 tests with N95s (82%), 5 (5%) with cloth masks, 4 (4%) with surgical masks, three (3%) with KN95s, three (3%) with Tyvek, and 1 (1%) with a plastic face shield and 1 (1%) unspecified.…”

“…More research is indicated to understand these results. Hydrogen peroxide disinfection (n=20) 15, 19, 27, 29, 30, 36, 45, 51, 57, 59-61, 68 , dry heat (n=19) 12, 16, 19, 21, 29, 33-35, 42, 45, 49, 50, 52, 54 , UVGI (n=13) 15, 16, 29, 35, 42, 45, 46, 52, 59-62 , and ethylene oxide (n=5) 19, 59-61 all had promising results. With hydrogen peroxide, no failures were seen in the course of the study in 14 tests (1-14 cycles), two failed at 14 and 29 cycles, and – using HPGP and HPAH, there were failures at 1-4 and 9 cycles, respectively.…”

“…Hydrogen peroxide disinfection (n=20) 15,19,27,29,30,36,45,51,57,[59][60][61]68 , dry heat (n=19) 12, 16, 19, 21, 29, 33-35, 42, 45, 49, 50, 52, 54 , UVGI (n=13) 15,16,29,35,42,45,46,52,[59][60][61][62] , and ethylene oxide (n=5) 19,[59][60][61] all had promising results.…”

Measurement of filtration efficiencies of healthcare and consumer materials using modified respirator fit tester setup

“…Much of the work to date has focused on sterilization of respirators for subsequent reuse. While a few studies have been completed and submitted to preprint servers after waiting for data from extant labs [24][25][26][27][28][29], a number of other preprints [30,31] and publications [32][33][34] have developed apparatuses to measure filtration efficiency as best they can independently. There is significant heterogeneity in these setups; some are built with assistance from labs which study aerosols, others with equipment found on hand.…”