Community Masks During the SARS-CoV-2 Pandemic: Filtration Efficacy and Air Resistance.

Many countries have introduced a compulsory use of community masks for certain public areas during the SARS-CoV-2 pandemic. Different manufacturers offer reusable community masks in large quantities. The efficacy of these masks, however, is unknown. We tested available community masks of major manufactures and determined the filtration efficacy using radioactive aerosol particles as well as air resistance with a vacuum measurement. Filtration efficacy of the tested reusable community masks ranged from 34.9% ± 1.25% to 88.7% ± 1.18%. Air resistance ranged from 4.3 ± 0.06 to 122.4 ± 0.12 Pa/cm. There was a good correlation between filtration efficacy and air resistance (Pearson correlation 0.938,  < 0.0001). Filtration efficacy and air resistance differ significantly between the different community masks, but the two measurements correlate well with each other within the entire test series. For optimal protection, one should select a rather airtight mask. When selecting a mask, the highest level of tolerable air resistance can be used as a selection criterion.