Plus, where you can buy them right now.

In the world of face masks, N95 is king. But, given that the Centers for Disease Control and Prevention recommends that they be reserved for healthcare workers, they're off the table. So, plenty of people have turned to KN95 masks, the Chinese equivalent of N95s. Unfortunately, there are a lot of counterfeits out there, making it tough to know if you're getting a quality mask.

That's why a growing number of people are using KF94 masks, the Korean version of an N95 mask. These masks, which are slightly different from N95s and KN95s, still offer high-level protection. And they're suddenly exploding in popularity.

Aaron Collins, a mechanical engineer in Minnesota and self-described "citizen engineer" has been testing the filtration properties of KF94 masks and talking up the benefits of these masks on YouTube. Collins tells Health he doesn't have any financial ties to KF94 makers and isn't looking to become a social media star—he just wants to inform the public about the best masks out there.

Collins has been cited by several doctors and engineers for getting the word out about KF94s. "I've been testing them and screening them, and talking about them from the top of my lungs," he says. Collins says he particularly likes the rigorous screening process for KF94 masks. "In South Korea, if you put a KF94 stamp on your masks and don't meet the standards, the government will fine you heavily," he says. "I like these masks because of the quality system in place."

He's not the only one giving KF94 masks the thumbs up—plenty of doctors do, too. Here's what you need to know about the masks everyone is suddenly talking about.

OK, what are KF94 masks, exactly?

The "KF" stands for "Korean Filter," Sara Andrabi, MD, assistant professor of emergency medicine at Baylor College of Medicine, tells Health. "The '94' represents the filtration efficiency, which means how good the mask is at filtering out particles. In this case, that is 94%."

"These are basically N95 masks, just from South Korea," infectious disease expert Amesh A. Adalja, MD, senior scholar at the Johns Hopkins Center for Health Security, tells Health.

Like N95 masks, KF94s have an adjustable bridge that can be manipulated to get a secure fit over the bridge of your nose. They also have side flaps to contour to your face. "These help close the gaps around the face and limit unfiltered air entry," Dr. Andrabi says.

KFN4 masks are disposable and are readily used in South Korea. "It is worn by the general public to help with filtering pollution and dust," Dr. Andrabi says.

And, along with N95s and (legitimate) KN95s, "these masks are the best types of masks to protect against COVID-19," Thomas Russo, M.D., professor and chief of infectious disease at the University at Buffalo in New York, tells Health.

How does a KF94 mask compare to an N95 mask or a KN95 mask?

An N95 mask (aka an N95 respirator) is a respiratory protective device that's designed to achieve a close facial fit and "very efficient filtration of airborne particles," according to the Food and Drug Administration (FDA). These masks filter out at least 95% of airborne particles, per the CDC. Similarly, KN95 masks are the Chinese equivalent of N95 masks.

KF94 masks are similar, but offer 94% filtration. "There is not much difference between 94 and 95% filtration," Dr. Andrabi says. But, she points out, fit is "an important factor" in how efficient these masks are as well. It's also important to note that KF94 masks are not on the FDA's list for emergency use authorized face masks, as of right now.

The shape of KF94 masks are different from N95 masks, too. Collins describes it as having a "boat-style design," with a wide band that wraps around the center of the mask. N95 masks, on the other hand, have either a cup or duck bill style. "The KF94 mask hits a much wider distribution of faces due to its shape," Collins says.

What do doctors think of KF94 masks?

Experts say they're worth trying. "Clearly, we need good masks now," Rajeev Fernando, MD, an infectious disease physician working in field hospitals across the country, tells Health. "N95 is the gold standard, followed closely by the KN95 and KF94."

But Dr. Adalja points out that KF94 masks—along with N95s and KN95s—can be harder to breathe in than cloth face masks. "They're more difficult to wear," he says, adding, "I don't think that the general public needs to wear a mask at this filtration level." Still, he says, a KF94 "doesn't take away from hospital supplies," which is important for the medical community.

In general, Dr. Andrabi says that "wearing masks help slow the spread of COVID-19" and the KF94 mask is "another type of mask that is available to the public." KF94 masks aren't perfect, though. "They don't last as long as a cloth mask and cannot be washed," Dr. Andrabi. But, she adds, "The most important thing is to 'mask up,' so wearing the mask you feel comfortable keeping on is of utmost importance."

How to buy KF94 masks

There are some KF94 masks for sale at Amazon, but Collins is concerned about potential counterfeits, given that this has been a problem for the site with other mask styles. "Amazon doesn't have any method of qualifying the vendor," he points out. "But, if you go to Target, Walmart, Lowe's, Ace Hardware, or a store like that, you know there was someone affiliated with the company who purchased those."

Right now, major retailers don't sell KF94 masks due to an export ban from South Korea that lasted until the end of July, Collins says, adding, "we're just now starting to see them come in."

Bizarrely enough, Collins says his tests have found the highest quality KF94 masks through Korean beauty websites like "These sites are the first to import these masks in the US," he says.

Pro tip, per Collins if you decide to try out KF94 masks: Do a small order and make sure the masks fit your face before ordering more. "If you find out they don't fit, you're going to be left with 99 other masks that don't work for you," he says.

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDCWHO, and their local public health department as resources.

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