The homemade face covering that best contains respiratory droplets like those from COVID-19 is a neck-gaiter-style mask combining a nose piece with an elastic cord wearers can toggle to snug the mask to their face, according to a UW-Madison engineer.
Mechanical engineering professor Scott Sanders, who uses lasers to study how gases and particles behave in combustion engines, applied his techniques to masks and coronavirus prevention. Using a mannequin, he studied how various types of mask styles and materials contain particles from coughs and sneezes.
With no mask, droplets travel more than 3 feet in front of the mannequin, and masks with one-way valves intended to protect the wearer allow many particles to escape, Sanders found.
Cloth masks do a better job of containing the particles, but those with a loose weave don’t perform as well as those made with tightly woven cloth, the study found. Masks without fitted nose pieces allow particles to escape through gaps in the top, under the wearer’s eyes. Other mask styles, including flat-fold masks, can leak particles out the sides near the ears.
Neck-gaiter-style masks were most effective, though they are larger and can't be easily removed.
“That said, wearers can quickly and easily slide the gaiter down around their neck and back up to their face as needed,” Sanders said in a statement.
The neck-gaiter mask can be a good alternative for small children or others for whom traditional masks might be difficult to fit, he said.
In a video, Sanders uses a mannequin to produce a simulated cough. The visualization doesn’t directly track the spread of virus particles but can help people see a risk that is otherwise invisible, he said. The video can be seen at go.captimes.com/mask.
“There are two aspects to masks: Personal protection, or reducing the amount of airborne droplets the wearer inhales, and source control, which is containing the wearer’s own respiratory droplets,” Sanders said. “The ideal mask would do an excellent job at both aspects, and work whether wearers are talking, yelling, coughing or sneezing."
A homemade cloth mask with a nose piece can provide significant source control, which in turn can improve public health, he said.