They work better than your brain does.

They do.

From: Verma, S., Dhanak, M., & Frankenfield, J. (2020). Visualizing the effectiveness of face masks in obstructing respiratory jets. Physics of Fluids, 32(6), 061708. https://doi.org/10.1063/5.0016018

TABLE I. A summary of the different types of masks tested, the materials they are made of, and their effectiveness in impeding droplet-dispersal. The last column indicates the distance traveled by the jet beyond which its forward progression stops. The average distances have been computed over multiple runs, and the symbol “∼” is used to indicate the presence of high variability in the first two scenarios listed.

Mask type Material Threads/in. Average jet distance

Uncovered … … ∼8 ft

Bandana Elastic T-shirt material 85 ∼3 ft 7 in.

Folded handkerchief Cotton 55 1 ft 3 in.

Stitched mask Quilting cotton 70 2.5 in.

Commercial maska Unknown Randomly assorted fibres 8 in.