A comparison of two approaches to screen the filtration properties of Materials during the COVID-19 Emergency Time

Determination of the filtration efficiency (even to nanosize) of several textiles was carried out during emergency time at the beginning of the COVID-19 pandemic lockdown in order to perform a fast screening of materials candidate for facial masks. At this purpose, a double strategy was adopted in Milan scanning electron microscopy investigation and a classical filtration test of ambient aerosol. The latter was used in order to mimic as much as possible the capability to filter ambient aerosol that might contain COVID-19. The two methods were compared to investigate their capability to identify only textiles characterized by a filtration efficiency higher than 90% (thus candidate for facial mask production). Results showed filtration efficiency above 90% for promising candidate textiles as well as poor filtration capabilities (below 60%) of other textiles, enabling a fast screening of the materials from different Italian factories.