The U.S. Centers for Disease Control and Prevention announced a change in its mask guidance recommending people to "wear the most protective masks that fit well and cover the face consistently."

The agency describes respirator masks approved by the National Institute for Occupational Safety and Health — such as N95 masks — as providing the "highest level of protection."

The updated guidance comes after many public health experts recommended wearing more effective masks — especially the N95 model — and that the CDC change its mask-wearing guidelines.

Recently, CNN medical analyst Dr. Lina Wen said that "cloth masks are nothing more than face decorations. They have no place amid the spread of Omicron."

Wen added that in crowded places, "KN95 or N95 masks are recommended," which cost only a few dollars.

Because they contain certain materials — such as polypropylene fibers — that act as mechanical and electrostatic barriers, these masks better prevent fine particles from reaching the nose or mouth and must fit your face properly to work effectively.

Here is what you need to know about masks like the N95 model and how to use them safely.

Why do experts now recommend wearing an N95 mask?

N95 masks are now more widely available than earlier in the pandemic, and U.S. public health experts also have a better understanding that the primary driver of coronavirus infections is shared air, according to Erin Bromage, an associate professor of biology at the University of Massachusetts Dartmouth, who told CNN last month.

Cloth masks — which were acceptable earlier in the pandemic — can filter large droplets, while more effective masks like the N95 can filter both large droplets and smaller aerosols or particles potentially carrying airborne viruses if infectious people are present.

Cloth face coverings also have an internal and external leakage rate of 75%, a figure described during the American Industrial Hygiene Conference as "the percentage of particles entering the face covering" and "the percentage of exhaled particles leaving the source and through the face covering," respectively.

On the other hand, N95 masks that cover the face properly and are certified by the National Institute for Occupational Safety and Health can filter up to 95% of airborne particles.
 

Although it is not currently known why many people are getting infected with the Omicron variant so quickly, this underscores the importance of wearing high-quality masks, Bromage noted.

What is the difference between N95 and KN95 masks?

The difference between N95 and KN95 masks is where each is certified, according to the Oklahoma State Department of Health.

The U.S. tests, certifies, and regulates N95 masks recommended by public health experts, while manufacturers in China test KN95 masks, but the country's government lacks a regulatory body to verify them, according to Aaron Collins, professor emeritus at Mercer University College of Engineering and a mechanical engineer with a background in aerosol sciences.

According to the U.S. Centers for Disease Control and Prevention, about 60% of KN95 respiratory masks evaluated by the National Institute for Occupational Safety and Health during the 2020 and 2021 pandemic did not meet the required standards.

Bromage explained that "if KN95 masks are manufactured to standards and certified by relevant boards in the country of origin, such as NIOSH here, they essentially all provide the same protection."

He added that they "may meet standards but are not certified."

However, masks such as the KF94, a Korean standard mask, are tested and regulated by the Korean Ministry of Food and Drug Safety, according to Kelly Carothers, director of government affairs and sustainability at Project N95, the national clearinghouse working to provide equitable access to personal protective equipment and coronavirus tests.

How can I spot fake N95, KN95, or KF94 masks?

The National Institute for Occupational Safety and Health maintains a list of approved N95 respirators.

These masks should have a cup shape, flat fold, or duckbill design; two straps that go around the head; an adjustable wire nose bridge; and proper markings indicating NIOSH approval, according to the CDC.

The agency also has resources for identifying counterfeit N95 masks, including the complete absence of markings on the mask or incorrect spelling of the National Institute for Occupational Safety and Health.

Can children wear N95, KN95, or KF94 masks?

N95 masks are medical masks designed for healthcare workers, so naturally, there are no N95 masks designed or made for children since only adults work in healthcare settings.

However, larger children in elementary to middle school and above can wear N95 masks that come in small sizes made for adults, according to Lindsey Marr, professor of civil and environmental engineering at Virginia Tech, who told CNN this month.

Marr noted that N95 masks marketed for children should raise suspicion of being counterfeit.

There are KN95 and KF94 masks designed for children; however, you should ensure to obtain them from a trusted source.

Marr added, "Certainly, for children, KN95 or KF94 masks will provide better average protection than surgical or cloth masks."

If you have trouble securing KN95 or KF94 masks on your child's face regardless of how many brands you try, you can tie the ear loops or use a velcro wire lock to ensure a sufficiently tight fit, Marr suggested.
 

Is it safe to reuse N95 masks?

Bromage explained that in medical settings, healthcare staff often change masks to avoid contaminating the patient's room with equipment worn in a different place with an infectious person.

So, you can reuse your N95 mask.

Even after wearing an N95 mask in a closed and crowded place — such as a subway or grocery store — the N95 material and its filtration ability will not "break down unless you rub it or poke holes in it," Marr explained, noting that she wears an N95 mask for a week.

Marr explained, "You need to be in really polluted air ... for several days before the mask loses its filtration ability."

However, there are cases to consider for safe reuse of an N95 mask, for example when putting it on, avoid touching the front outer part of the mask; instead, handle it by the edges or ear straps.

If you know you were near a person infected with coronavirus while wearing an N95 mask, you should discard that mask to avoid risking exposure to the virus, according to Bromage.

Unknowingly being exposed to infected people while wearing an N95 mask is possible, so distancing as much as possible can help reduce risks.

If the mask becomes damp, visibly dirty, bent, difficult to breathe through, or damaged — including from cosmetics — you should replace it to avoid wearing a less effective mask.

Is there a way to clean an N95 mask?

You should not wash an N95 mask because water will dissipate the mask’s static charge, which helps it filter viruses well, Marr said.

She added that what you can do is to set the mask aside because particles will disappear within several hours, and this will happen faster when exposed to sunlight.

But the fact that warmer temperatures can have a "sanitizing" effect on an N95 mask does not mean you should put masks in the microwave, as that can ruin the mask.