COVID-19: Permeability of FFP2 masks

We have performed measurements showing that the permeability of a FFP2 mask is not changed after several cleanings with 99% grade ethanol, allowing the possibility to clean and reuse masks.

In this publication, we assess the effect of ethanol on the filtering properties of FFP2 masks. The permeability of parts of a FFP2 mask is measured before and after several cleanings with 99% ethanol (no shear forces are applied).
Like for any porous medium, the filtering properties of a mask are related to the size and tortuosity of the pores, and are quantified by its permeability. Any damage to the filter will change its permeability.
We show that after 6 cleaning cycles, the permeability remains very close to the initial permeability.
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 masks from different manufacturers need to be performed.

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