Coughing over trays of liquid nitrogen with and without N95 mask, face shield, and surgical mask. pic.twitter.com/x3Th6kzed2— Tom Kuntzleman (@pchemstud) July 21, 2020
Coughing over trays of liquid nitrogen with and without N95 mask, face shield, and surgical mask. pic.twitter.com/x3Th6kzed2