To compare the effectiveness of cotton and surgical masks, a group of patients infected with SARS-CoV-2 coughed into petri dishes while wearing no mask, a surgical mask, and a cotton mask. The mask surfaces were swabbed afterward to assess viral positivity on the mask itself.
The median nasopharyngeal and saliva viral load was 5.66 log copies/mL and 4.00 log copies/mL, respectively. The median viral loads after coughing was 2.56 log copies/mL without a mask, 2.42 log copies/mL with a surgical mask, and 1.85 log copies/mL with a cotton mask. All outer surfaces of the mask were positive for SARS-CoV-2, while most inner surfaces were negative.