How to Make a More Effective Face Mask

Choosing the right fit

"Fit is really important, because if there are any leaks … your mask isn't doing its job,” Marr says. The CDC recommends a mask that fits snugly around the nose and chin, with no large gaps around the sides of the face.

To that end, Marr recommends looking for masks with a nose wire, which can be shaped to conform to the bridge of your noise, and considering masks that have ties instead of ear loops, since they can be positioned on the head for a custom fit (also a good alternative for people who find that ear loops cause soreness).

Fit is also the main reason face shields shouldn't be worn alone as a substitute for a cloth mask, Marr says, since the large gaps along the sides of the shield allow for unrestricted airflow.

Fabric and filter options

Marr and her team found that commonly available materials like the thin, tightly woven cotton you might find in a blouse performed well in the study, especially when used as the two outer layers in their recommended three-ply mask with a middle filter layer (the filters they tested included DIY options like vacuum bags and coffee filters).

Some cloth face masks come with an inner filter layer already included, or have a pocket into which one can be inserted. If you don't have a mask with a filter or don't want to embark on a DIY project to add one, Marr recommends a simple alternative: simply wear a surgical mask under a well-fitting cloth mask for added protection.

Avoiding common mask mistakes

Even the best mask won't work well if worn incorrectly. Marr says common mask-wearing errors include leaving your nose outside of the mask and pulling your mask down to talk to someone. “That's when you most need the mask,” she says, “in terms of protecting others.”

Other mask don'ts, according to the CDC, include:

• Single-layer cloth masks
• Masks with exhalation valves or vents
• Masks made from either loosely woven fabric or materials that are hard to breath through (like plastic and leather)