With a supply crunch in medical-grade facemasks, the general public has been turning to homemade masks in order to slow the spread of COVID-19. Now researchers are using lasers to reveal how effective different kinds of DIY masks are at blocking tiny droplets from coughs and sneezes.
The 4-minute video above shows findings from research just published by scientists at Florida Atlantic University’s College of Engineering and Computer Science in the journal Physics of Fluids.
The flow visualization was created by pointing a camera at a laser light sheet and then shooting a water/glycerin mixture out of a mannequin’s mouth to simulate coughing and sneezing.
Using the setup, the scientists captured the path of droplets through masks ranging from thin bandana-fabric facemasks to professional-grade masks.
The camera revealed that without a mask, droplets could travel up to 12 feet within 50 seconds — significantly farther than the 6-foot distancing guidelines recommended in the United States.
A bandana reduced the distance to 3’7″ (1.09m), a folded cotton handkerchief brought it down to 1’3″ (0.38m), a cone-style mask had a travel of 8″ (0.2m), and a stitched quilting cotton mask reduced it to 2.5″ (0.064m).
“Our researchers have demonstrated how masks are able to significantly curtail the speed and range of the respiratory droplets and jets,” says FAU College of Engineering and Computer Science dean Stella Batalama. “Moreover, they have uncovered how emulated coughs can travel noticeably farther than the currently recommended six-foot distancing guideline.”
We previously showed a different visualization of facemask effectiveness captured using Schlieren imaging.
If you’re looking to buy medical-grade facemasks, the camera superstore Adorama (a long-time sponsor of PetaPixel) has a wide-range of PPE , including N95-equivalent facemasks, in stock.