Evaluation of filtration efficacy of various types of facemasks using ambient and PAO aerosols following with different sterilization methods

Kumar, Amit; Bhattacharjee, Basundhara; Sangeetha, D.; Subramanian, V.; Venkatraman, B.

doi:10.1101/2020.10.23.20218073

Cited by 5 publications

(15 citation statements)

References 18 publications

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“…Also, our data observed that cloth mask (FE=23.2-75.4%) and unsealed surgical mask (FE=37.4-66.4%) offered comparable FE at particle sizes between 0.3 and 5 µm. In agreement with our findings, a recent report showed almost equal FE of cloth masks (FE=19.5-81.8%) and unsealed surgical masks (FE=20.8-77.3%) at particle sizes between 0.3 and 5 µm (Kumar et al, 2020).…”

Section: Discussionsupporting

confidence: 93%

Filtration efficiency of face masks and veils as protective measures during COVID-19 pandemic

Al-Hadyan

Al-Harbi²,

Judia³

et al. 2021

KJS publishes peer-review articles in Mathematics, Computer Sci

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Wearing face masks have been implemented as a public and personal health control measure against the spread of coronavirus disease (COVID-19). However, the protection level of nonmedical face masks, such as women face veils, is still uncertain. This study aimed to assess the filtration efficiency (FE; percentage of particles retained by a mask) of different types of medical masks (either as sealed or unsealed, single or doubled), non-medical masks (cloth masks) and face veils. FE of face masks was evaluated using an in-house 3D-printed air duct connected to the Aerotrak particle counter with a capability of counting particle sizes of 0.3, 0.5, 0.7, 1, 2 and 5 μm. A set of 10 earloop surgical masks,10 tie-on surgical masks, 3 triple-layers reusable cloth masks and 3 types (short, medium and long) of traditional face veils were included in the study. The unsealed surgical masks showed intermediate FE (36.54-80.58%), with no observed differences between tie-on and earloop or single and doubled masks. For each mask type, the mean FE values of sealed surgical masks (FE≥99.16%) was significantly higher (P<0.001) than the unsealed ones (FE≤80.58%). No significant difference was observed in the mean FE values between unsealed surgical masks and either cloth masks (FE=23.19-75.35%, P=0.26) or face veils (FE=19.10- 70.68%, P=0.14). However, a mockup experiment showed that wearing a surgical mask under the face veil significantly improve the FE (33.73-79.18%; P<0.001). We conclude that besides sealed surgical masks that ensure optimal filtration under the experimental conditions, the unsealed surgical and cloth masks and face veils showed comparable performance and acceptable protection at 5 μm particle size, which is the most relevant particle size associated with COVID-19 infectious droplets. Wearing a surgical mask under the face veil significantly improves the FE compared to wearing a face veil alone.

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Section: Discussionsupporting

confidence: 93%

Filtration efficiency of face masks and veils as protective measures during COVID-19 pandemic

Al-Hadyan

Al-Harbi²,

Judia³

et al. 2021

KJS publishes peer-review articles in Mathematics, Computer Sci

View full text Add to dashboard Cite

show abstract

“…Another study also observed a stable FE (only 0.4% reduction in FE) of 3M-1860 N95 following a single STERIS-VHP cycle using the NIOSH assessment method to evaluate FE [ 46 ]. Furthermore, four reports confirmed the latter studies and showed that 3 to 10 VHP cycles did not affect the FE stability of different types of 3M-N95 masks [ 47 , 48 , 49 , 50 ].…”

Section: Discussionmentioning

confidence: 65%

In-House Filtration Efficiency Assessment of Vapor Hydrogen Peroxide Decontaminated Filtering Facepiece Respirators (FFRs)

Al-Hadyan

Nobah

Lindstrom

et al. 2021

IJERPH

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To cope with the shortage of filtering facepiece respirators (FFRs) caused by the coronavirus disease (COVID-19), healthcare institutions have been forced to reuse FFRs using different decontamination methods, including vapor hydrogen peroxide (VHP). However, most healthcare institutions still struggle with evaluating the effect of VHP on filtration efficiency (FE) of the decontaminated FFRs. We developed a low-cost in-house FE assessment using a novel 3D-printed air duct. Furthermore, we assessed the FE of seven types of FFRs. Following 10 VHP cycles, we evaluated the FE of KN95 and 3M-N95 masks. The 3M-N95 and Benehal-N95 masks showed significant lower FE (80.4–91.8%) at fine particle sizes (0.3–1 µm) compared to other FFRs (FE ≥ 98.1%, p < 0.05). Following 10 VHP cycles, the FE of KN95 masks was almost stable (FE stability > 99.1%) for all particle sizes, while 3M-N95 masks were stable only at 2 and 5 µm (FE stability > 98.0%). Statistically, FE stability of 3M-N95 masks at 0.3, 0.5, and 0.7 µm was significantly lower (p ≤ 0.006) than 2 and 5 µm. The in-house FE assessment may be used as an emergency procedure to validate the decontaminated FFRs, as well as a screening option for production control of FFRs. Following VHP cycles, both masks showed high stability at 5 µm, the size of the most suspected droplets implicated in COVID-19 transmission.

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“…Several non-traditional sterilization/decontamination methods have evaluated with various successes (Hearn et al, 2020 and Kumar et al, 2020 c). Many potential sterilization methods have been explored already, and they are based on chemical and physical processes.…”

Section: Introductionmentioning

confidence: 99%

“…The dry/ steam heat treatment has emerged as a promising and straightforward reprocessing method of respirators with good scalability and uniformity disinfection (Xiang et al, 2020; Liao et al, 2020). The steam sterilization by autoclave found helpful as far as filtration efficiency, but it has slightly melted the N95 mask plastic cord (Kumar et al, 2020 c). However, understanding the physical and chemical changes induced by the above various treatments remains unexplored or incomplete in a few cases.…”

Section: Introductionmentioning

confidence: 99%

Assessment of N95 respirator for reuse after sterilization: filtration efficacy, breathing resistance, quality factor, chemical structure and surface charge density

Kumar

Subramanian

Joshi

et al. 2021

Preprint

Self Cite

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In the present ongoing pandemic, the N95 respirator is an essential protective barrier to suppress the spread of the SARS-Cov-2 virus and protect the frontline worker from exposure. The N95 respirators are meant for single usage; however, they can be used after decontamination in-light of the economy and shortfall in availability. At this juncture, the respirators performance after various types of sterilization and usage condition is required to be analyzed in detail. With this motto, this work has proceeded. The filtration efficiency, pressure drop, and quality factor of the respirator are evaluated for two face velocities (5.8 and 26.4 cm/s) following different sterilization methods. Sterilization techniques used here are dry air oven heating, gamma irradiation, and immersing in a 10% concentration of liquid hydrogen peroxide. The particle filtration performance and electrostatic surface charge density measurement are used to determine the facemasks efficacy after sterilization. The methods recommended to sterilize N95 masks without affecting their performance are (i) using dry air heat at 80oC and (ii) H2O2 soaking. The highest reduction in filtration efficiency is observed to be 30-35% after gamma irradiation due to a change in the electrostatic properties of the respirator layers. However, the filtration efficiency does not change significantly for other sterilization methods despite a change in charge density, but there is no direct correlation with filtration efficiency. Electrostatic charge measurement of the filtration layer is a crucial indicator of filtration efficiency degradation. Policymakers can use these data during potential future N95 shortage to assess the viability of sterilization methods.

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Evaluation of filtration efficacy of various types of facemasks using ambient and PAO aerosols following with different sterilization methods

Cited by 5 publications

References 18 publications

Filtration efficiency of face masks and veils as protective measures during COVID-19 pandemic

Filtration efficiency of face masks and veils as protective measures during COVID-19 pandemic

In-House Filtration Efficiency Assessment of Vapor Hydrogen Peroxide Decontaminated Filtering Facepiece Respirators (FFRs)

Assessment of N95 respirator for reuse after sterilization: filtration efficacy, breathing resistance, quality factor, chemical structure and surface charge density

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