Which mask is best? UW engineering professor studies how droplets escape from face coverings

University of Wisconsin-Madison engineer Scott Sanders usually spends his time figuring out how gases and particles behave in combustion engines.

But Sanders has turned his expertise to determining how a different type of particle, one that has sickened millions around the world, moves from human mouths covered with masks.

The UW mechanical engineering professor normally uses lasers to characterize the way gases and particles move in engines. But since the coronavirus pandemic swept the planet, Sanders is now studying mask materials, construction, fit and filtration.

UW-Madison engineering professor Scott Sanders

Which is certainly timely now that pretty much everyone is wearing a mask or being asked or required to wear one in public.

While experts say that wearing a mask helps lessen the spread of the coronavirus, not all masks are equal. That’s where Sanders’ research is helping pull back the mask, in a way, to show how droplets move when someone coughs while wearing one.

In a cool video posted online this week, Sanders uses a mannequin to illustrate how droplets escape or stay contained inside a variety of masks now being worn.

Sanders, who conducts much of his research through the UW-Madison Engine Research Center, used lasers to show how particles can escape depending on the type of mask, something that’s invisible to humans.

His research showed that masks with valves allow particles to escape through the valves. Flat-fold masks allow particles to leak out next to ears.

Cloth masks made of loose weave ā€” where light can be seen when held up to the sun or a lamp ā€” don’t perform as well as those made from tightly woven cloth. And cloth masks without fitted nose pieces, usually a wire that can be pinched across the nose to form a tighter seal, allow particles to escape under the eyes of those wearing them.

The best mask to prevent droplets from venturing out and swirling around in the air? Neck gaiter-style masks that combine a nose piece with an elastic cord to draw the mask tight against the face.

ā€œI hope that research like this will enable people to make informed decisions about distancing and mask-wearing,ā€ Sanders said.

Sanders received funding for his research and to produce the videos through the Wisconsin Partnership Program in the UW School of Medicine and Public Health.