Any common face mask provides significant protection against the virus that causes COVID-19, but N95 masks are most effective at slashing the amount emitted by infected people, according to a University of Maryland-led study released Wednesday.
So-called “duckbill” N95 masks scored highest in the study, which measured the exhaled breath of participants who were tested both masked and unmasked to measure comparative outputs of SARS-CoV-2. The inexpensive masks, which have two head straps and a horizontal seam, captured 98% of exhaled virus, according to the study published in
eBioMedicine.
The researchers also found that—in what might come as a surprise to many—cloth masks outperformed the specific brand of KN95 mask that was tested. Surgical masks brought up the rear in performance out of the four types, but even they blocked 70% of the virus, the tests showed. (To reflect the general public’s use of masks, study volunteers were not fit-tested for their masks or trained how to properly wear them.)
“The research shows that any mask is much better than no mask, and an N95 is significantly better than the other options. That’s the No. 1 message,” says the study’s senior author, Donald Milton, a professor of environmental health and a global expert on how viruses spread through the air.
“our data suggest that a mildly symptomatic person with COVID-19, not wearing a mask or respirator, would exhale on average 2800 RNA copies per hour in their total exhaled aerosol or a little more than two infectious doses, quanta, per hour. However, wearing a N95 respirator would reduce the aerosol shedding rate to less than one tenth of a quantum per hour. “
