What to Know About the KF94 Mask

Even as mask mandates begin to lift across the country, many people still need high-quality masks for air travel, shopping and visiting the doctor. One of the best options is the KF94 from South Korea.

KF94 stands for “Korean filter” and “94 percent” filtration. The KF94 was developed in South Korea for public use, and unlike the N95, which is the respirator-style mask approved in the United States, the KF94 is available in adult and child sizes. In Korea, the masks range in price from 529 won to 1,244 won (about 50 cents to $1); most online sellers in the United States charge about $1 per mask. Like other respirator-style masks, a KF94 can be worn for a total of about 40 hours, in any combination of short or long increments, as long as it remains clean and continues to fit snugly on the face.

A more breathable mask

Many users say the KF94 is more comfortable and easier to speak and breathe in than other respirator-style masks, because the design creates more space between the mask and the mouth. The mask, which has ear loops, arrives flat in a single package and unfolds to reveal extra flaps, including one with a moldable nose bridge, that give complete coverage from the top of the nose to under the chin, with no gaps.

Yoon S. Byun, a photographer and filmmaker in Portland, Maine, recently purchased KF94s for his children, who are 4 and 6, after reading about them in The New York Times. (Mr. Byun has freelanced for The Times.)

“Our kids are pretty good about keeping masks on, but it took a day or so for them to get used to the two flaps, and every morning we pinch the nose part before they go to school so they conform to their faces,” Mr. Byun said. “Previously, our younger son would go through at least two cloth masks a day because they would get soaked, but he’s able to wear these all day because they don’t press up against his mouth. Both seem to like them and say they’re easy to breathe in.”

Stricter regulatory controls

Dr. Ashish Jha, dean of the Brown University School of Public Health, said one of the benefits of the KF94 is that Korea imposes strict controls on mask production and approval.

For a mask to be certified by the Ministry of Food and Drug Safety in South Korea, mask makers must submit an application that includes details about product development, lab test data and evidence of product safety and efficacy. The ministry inspects several thousand masks a month to make sure they meet government standards, according to a written statement from an MFDS representative.

Although some counterfeit KF94s have emerged in recent months, overall there seem to be fewer counterfeits in the supply chain compared with N95s or KN95s, the respirator-style masks approved in China. “It’s a much, much tighter regulatory regime,” Dr. Jha said.

The penalties for selling an unapproved mask or one that does not meet standards are steep, including fines, suspension of product sales and up to five years in prison. In recent months, the ministry has been involved in several high profile crackdowns on illegal mask production and distribution. In April 2021, the agency prosecuted four people for selling 11.4 million fake masks. And in December, the ministry uncovered 16 companies in Busan, South Korea’s second largest city, that were manufacturing and selling fake masks.

How to spot a counterfeit KF94

Despite the agency’s efforts, some counterfeit masks have still found their way to online stores, including on Amazon, so it’s important to look for a few key features to make sure you’re getting a real KF94.

While the MFDS has a portal to check whether a mask has been approved, it’s useful only if you can read Korean. When we used the English version of the site, the search function didn’t work. Recently, we used the Korean database to look up 17 different KF94 mask brands being sold on Amazon. Eleven of the brands were legitimate, five were counterfeits and the status of one was unclear.

The legitimate masks we found on Amazon include those made by KN Flax, LifeSys AST Keep, Happy Life/Good Day, Instalashes, Yolo Studio, AnyGuard, Happy Day, Happy Life Kids, FlexMon, Petseeker and Puremate. But given that counterfeiters can copy brand names, you still need to do some homework and check for other indicators that the mask meets KF94 standards before you buy it.

Aaron Collins, an engineer who routinely tests masks and has gained a following on YouTube as the “mask nerd,” recommends buying KF94s from Korean beauty product importers like Be Healthy or KMact. Mr. Collins has also created a spreadsheet showing all of the KF94 and other mask brands he has tested. Look in the “filtration efficiency” column to see how the mask performed.

The MFDS offers additional guidance for finding a certified KF94. Here’s what to look for.

• Made in Korea. The mask should state clearly on its website and packaging that the product is made in Korea. Any mask that claims to be “KF94-style” or is made in China or another country is not a real KF94. Don’t buy it.

• Flat, glossy, single-use package. KF94s come in single-use flat envelope-style packages with a notch at the top to tear open. The package should have a glossy finish and a lightly-textured border. Recently one of our family members ordered some masks from Amazon that claimed to be made in Korea, but once they arrived there were 10 per package, signaling to us right away they weren’t legitimate. We returned them and ordered Happy Day masks, which met all of the requirements.

• Specific language in the corner of the package. For masks printed in Korean, the package should have “의약외품” or the word “quasi-drugs” in one of the corners of the packaging. But this may not be found on some KF94 masks printed in English. For instance, Happy Life’s masks sold on Amazon don’t include the lettering on its English-language package, but do have it on the Korean-language package.

• MFDS certification on the website. Most legitimate mask makers will provide proof of MFDS certification on their website or if you ask. For instance, we emailed Lifesys AST Keep masks, and the company replied with a copy of their certificate within a day.

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