Assessment of Fabric Masks as Alternatives to Standard Surgical Masks in Terms of Particle Filtration Efficiency

Amy V Mueller; Loretta A Fernandez

Mask fit testing is usually conducted using a single instrument in fit test mode, which sequentially tests air inside and outside the mask. Here in order to collect and display continuous data for ambient air and inside mask air at high frequency during minute-long tests, two PortaCount instruments were used. Two tubes of equal length sample air just inside and outside of each mask. Air inside the mask was sampled through a tight-fitting grommet inserted into each mask and positioned at the philtrum of the upper lip. Ambient air was sampled from a position ~3 cm from the grommet on the outside of the mask. All tests were conducted while masks were being worn by the same subject, breathing normally, through the nose, with the mouth closed, while holding the head at a steady position. Tests using multiple subjects, motions, and positions were not feasible given the limited time and social distancing precautions, however prior research results (van der Sande et al. 2008) provide confidence that limitation of motions and positions does not significantly limit the conclusions that can be drawn from the resulting data. author/funder, who has granted medRxiv a license to display the preprint in perpetuity.