COVID-19 changes. Masks should, too.
What type of mask should I buy?
By now you’re probably familiar with surgical masks. Maybe you’ve heard of N95s and KN95s. Let’s break down how they differ.
Surgical masks — typically blue on the outside — are made with soft, permeable material and have ear loops. They’re looser-fitting on the face, meaning leakage occurs around the edge of the mask when the wearer breathes in and out.
N95 respirators are made of tough yet flexible material and are tested and regulated by the National Institute for Occupational Safety and Health, or NIOSH. N95s are designed to have a very close fit and form a seal around the mouth by strapping around the back of the head.
KN95s, meanwhile, are similar to N95s but are certified by the Chinese government and don’t fit quite as tightly. Like surgical masks, KN95s have straps that loop around the ears. Both N95s and KN95s are ideal in crowded indoor settings with poor ventilation when not everybody around you is masking. “They really enhance your own personal protection,” Dr. Moffa said.
Surgical masks, N95s and their equivalent are all made of multiple layers of non-woven polypropylene, a material with an electrostatic charge that allows it to trap particles. The difference is in the fit of the mask, how they’re certified and the amount of particles they can filter out.
How effective are various masks?
“The material and type of mask are important considerations for the amount of aerosols at different size ranges that they can filter out,” said Seema Lakdawala, an associate professor of microbiology and molecular genetics at the University of Pittsburgh School of Medicine.
“A well-fitted mask that is
made of multiple layers of tight woven material worn around their nose and mouth is a good place to start,” she said.
A randomized study of more than 350,000 individuals carried out in rural Bangladesh in 2020 found that people were 9% less likely to develop COVID-19 when around 42% of villagers wore cloth masks. When surgical masks were introduced, people were 11% less likely to get sick. The findings were published in December in the journalScience.
Other studies have shown that multi-layer cloth masks
can block between 50% to 70% of large droplets and smaller particles when they’re worn snug to the face. N95s and KN95s get their name because they filter out at least 95% of all airborne particles, including large droplets and much smaller particles. Surgical masks can filter out larger particles but not smaller ones.
Can I reuse medicalgrade masks?
The short answer is yes. But the experts we talked to said how often you replace them will depend on how long you wear them and in what settings. You can rotate them out just like cloth masks, but you can’t wash surgical masks or N95 respirators.
You should throw away masks if they get wet, soiled or stretched or when they can no longer stay on your face. Discard any masks with holes or torn straps. You should store your masks in a place where they won’t get wet or be exposed to direct sunlight. Ultraviolet light can degrade N95s and KN95s over time.
Where can I find better quality masks?
For high-filtration masks, you’ll likely have to shop online, although some retailers like Lowe’s and Home Depot carry N95 respirators. Wellknown brands include 3M, Honeywell and KimberlyClark.
The Centers for Disease Control and Prevention has a list of NIOSH-approved N95 respirators and ProjectN95. provides links on where to purchase them.
KN95s are widely available on Amazon, but the CDC has warned that about 60% of KN95 respirators available in the United States are counterfeit and don’t meet NIOSH standards. It can be difficult to spot counterfeits, but the Food and Drug Administration has published a list of models that are no longer authorized to help consumers navigate purchasing these masks.
Are there any alternatives?
N95 respirators can feel harder to breathe through than a cloth mask, so those with chronic respiratory, cardiac, or other medical conditions should check with their health care provider before using one.
Others may find N95s or KN95s uncomfortable or illfitting.
If you can’t find a model you like, you can layer a cloth mask over a surgical mask to better lock in that seal. Many cloth masks also have pockets for non-woven polypropylene filters, which boost protection. It may take some trial and error to figure out what’s most comfortable for you.
“Any mask is better than no mask, and that’s really the message,” Dr. Bogen said, “but the mask does have to be worn properly.”