Effect of ethanol cleaning on the permeability of FFP2 mask

  1. Roland Lenormand
  2. Guillaume Lenormand

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Abstract

In this study we assessed the effect of ethanol on the filtering properties of FFP2 masks. The permeability of parts of a FFP2 mask was measured before and after six cleanings with ethanol. As for any porous medium, the filtering properties of a mask are related to the size and tortuosity of the pores of the filter, and are quantified by its permeability. Any damage to the filter will change its permeability. We show here that after six cleaning cycles, the permeability remains very close to the permeability before cleaning. Amid the COVID-19 pandemic and the shortage of protective masks, this study suggests that ethanol could be used to sanitize a FFP2 mask without significantly altering its filtering properties. Additional measurements on FFP2 and N95 masks from different manufacturers need to be performed to validate this study.

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  1. ScreenIT

    SciScore for 10.1101/2020.04.28.20083840: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    Limitations of the study: This study suggests that ethanol could be used to sanitize a FFP2 mask without significantly altering its filtering properties. Measurements were performed on masks from only one manufacturer, therefore it is not established whether or not the results presented here can be extrapolated to masks from different manufacturers. Furthermore, this study did not assess the aerosol filtration directly, as defined in the EN 149:2001 performance standard. However it is highly probable that the aerosol filtration properties remain unchanged after ethanol cleaning for two reasons. First, the permeability measurements demonstrated that the pore structure of the filter was unchanged by the sanitization protocol. Secondly, ethanol cleaning is not expected to change the wettability of the filter. The filter should remain hydrophilic; water wettability is necessary to retain the aerosol droplets. However, this assumption should be confirmed by a laboratory that is capable of performing the appropriate aerosol tests. Finally, the sanitization protocol used here, a 1 hour soak in 99% ethanol, was not optimized to eradicate microbes and viruses. We assumed that ethanol would be a likely candidate for such usage, as it is mostly safe and widely available. The Centers For Disease Control proposes several sanitization protocols using ethanol (8). Most of these protocols include a soak for 5 to 10 min in 70% ethanol; or 5 min in 70%-90% isopropyl alcohol. The protocol in th...

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

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  2. Version published to 10.1101/2020.04.28.20083840v1 on medRxiv