FIG. 2.

(a) Typical cough without a mask. (b) Typical cough with a disposable surgical mask. (c) Typical cough with an N95 mask. (d) Covering the mouth with one hand. (e) Covering the mouth and nose by cupping both hands. (f) Using a 40 × 40 cm² handkerchief folded over four times. (g) Covering the mouth with the hand while wearing a disposable surgical mask. (h) Coughing into a bare elbow (no shirt sleeve). (i) Coughing into the elbow while wearing a shirt with a long sleeve that covers the nose. (j) Visualization of the wavefront motion from a cough initiated 2.0 m from the center of the mirror (no mask case). For reference, the diameter of bright circular images of the mirror is 300 mm. Refer to Fig. 6 to see how a typical test subject covers the nose and mouth while coughing.