Is it time to upgrade your mask for better protection against COVID-19?

Tara Parker-Pope

CNA/ THE NEW YORK TIMES – By now most of us have settled on a preferred cloth mask to protect ourselves and others from coronavirus. But new research shows that a few simple upgrades in fabric, filters and fit are likely to provide even more protection.

Professor of Civil and Environmental Engineering Linsey Marr at Virginia Tech and one of the world’s leading aerosol scientists, led the research, which tested 11 different mask materials. The findings confirmed what other labs have found: You don’t need a gold-standard N95 medical mask to stay safe from coronavirus. The right cloth mask, properly fitted, does a good job of filtering viral particles of the size most likely to cause infection.

But Marr and her colleagues found that small improvements to your mask can go a long way toward improving how well the mask protects you and others from potential infectious particles. They found that:

THREE LAYERS ARE BETTER THAN TWO

The best mask has two tightly woven layers of outer material with a filter material sandwiched in the middle, Marr said. You can use surgical mask material or even a piece of a vacuum bag as a filter between two pieces of fabric. Coffee filters are an option, but can be less breathable. If you like your two-layer mask, you can just wear it over a surgical mask when you want added protection. A well-fitting fabric mask with a third filter layer can stop 74 per cent to 90 per cent of risky particles, the researchers found.

FLEXIBLE MATERIAL IS BETTER

Stiff material creates gaps. Look for a mask made of tightly woven flexible material that contours to your face. Masks with wire that can be moulded around the nose also fit better by closing gaps where air can escape out and seep in.

TIES ARE BETTER THAN EAR LOOPS

Masks that tie around your head fit better and can be more comfortable. Ear loop masks can leave bigger gaps around your face and cause ears to become sore with longer use.

FACE SHIELDS SHOULD BE USED WITH A MASK

Face shields alone offered little to no protection. Although the clear plastic shield is impermeable, air seeps out and comes in around the edges of the shield. “It was the worst of everything,” said Jin Pan, a civil and environmental engineering PhD student who was a co-author of the study. A face shield combined with a mask offers added protection, particularly for the eyes.

A WELL-FITTED MASK PROTECTS THE WEARER

Marr and her colleagues tested cloth masks for how well they protected others (outward protection) as well as the wearer (inward protection). Although masks are most efficient at filtering outgoing germs, they do stop incoming germs at nearly the same rate in most cases, the researchers found. Masks that did a poor job protecting the wearer were those made of stiffer materials and those worn loosely and with gaps around the edges.

A recent study from Denmark suggested that masks don’t protect the wearer, but Marr noted that in that study, many people weren’t using masks properly.

The research should also reassure people about the benefits of cloth masks, Marr said. She noted that masks can’t do “100 per cent of the work”, and it’s important to combine mask wearing with other measures, like hand-washing and restricting social contacts.

“Something is better than nothing,” Marr said. “Even the simplest cloth mask of one layer of material blocks half or more of aerosols we think are important to transmission. If you go to a tighter weave and more layers, you’ll get even better performance.”