How facemasks protect against COVID-19


The “new normal” is a way of living that helps prevent contracting the novel coronavirus. These include practices such as wearing masks in public places and staying at least six feet from each other. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes the coronavirus disease (COVID-19), can be transmitted via respiratory droplets when a person sneezes, coughs, or talks.

Wearing of masks has been recommended by health experts, including the World Health Organization (WHO) and the U.S. Centers for Disease Control and Prevention (CDC). There are many types of masks used today, including handsewn ones and those which have PM2.5 filters. Putting surgical masks and N95 masks that should be intended for healthcare workers, what masks provide the best protection against the novel coronavirus?

UW-Madison Professor Scott Sanders

UW-Madison Professor Scott Sanders’ team modified a mannequin so that the mouth releases a puff of air containing fog.

Video simulation

A new video simulation provides an overview of why it is essential to wear a face mask to prevent the spread of the new coronavirus.

Mechanical engineering professor Scott Sanders, who utilizes lasers to study how gases and particles behave in combustion engines, applied the technique to masks. He used a mannequin to examine how various mask types, styles, and materials contain particles from coughs and sneezes.

He applied flow visualization in a laboratory setting using a laser light sheet and a mixture of distilled water and glycerin to generate the synthetic flog, which made up the content of a cough-jet.

The masks tested were available to the general public, including a single-layer bandana-style covering, a homemade mask stitched using two layers of cotton quilting (70 threads per inch), and non-sterile cone-style masks, which are available in pharmacies. These masks are the ones that do not risk the supply of medical and N95 masks for healthcare workers.

Masks that provide protection

Without a mask, the droplets produced by coughing can travel more than 3 feet in front of the mannequin, the video showed. Masks with valves even allowed many particles to escape. On the other hand, wearing a mask could reduce the distance to just about a few inches.

Cloth masks perform better in containing the particles, but those with a loose weave do not perform as well as those made with tightly woven cloth. Also, masks with no fitted nose pieces allow the particles to escape through the gaps under the person’s eyes. Other mask styles, like the flat-fold ones, can allow the particles to leak out of the sides near the ear area.

The video simulation also revealed that some cloth materials work better than others at stemming the spread of infectious droplets. For instance, the homemade style masks like the neck-gaiter-style ones are most effective in containing the droplets. These masks combine a nose piece with an elastic cord that wearers can toggle to snug the masks to their faces. Though it is the most effective mask, it isn’t easily removed, and it is larger than the other styles.

He also recommends this type of mask for children or others whom conventional masks are hard to fit. The mask may also be comfortable for those who are sensitive to use other mask styles due to underlying respiratory issues.

“There are two aspects to masks: Personal protection or reducing the number of airborne droplets the wearer inhales, and source control, which is containing the wearer’s 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,” he added.

The U.S. Centers for Disease Control and Prevention (CDC) recommend using cloth face coverings to help protect people with COVID-19 from spreading the virus to others. Also, wearing cloth face coverings may reduce the spread of COVID-19 when most people use them in public settings.

“The spread of COVID-19 can be reduced when cloth face coverings are used along with other preventive measures, including social distancing, frequent handwashing, and cleaning and disinfecting frequently touched surfaces,” the CDC said.

“The cloth face coverings recommended here are not surgical masks or respirators. Currently, those are critical supplies that should be reserved for healthcare workers and other first responders. Cloth face coverings are not personal protective equipment (PPE). They are not appropriate substitutes for PPE, such as respirators (like N95 respirators) or medical facemasks (like surgical masks) in workplaces where respirators or facemasks are recommended or required to protect the wearer,” the agency added.





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