What's the difference between KN95 and KF94 masks?

As the Omicron variant continues to drive rapid spread in Canada, experts and public health officials are once again driving home the importance of wearing a properly fitted medical-grade mask to prevent transmission of COVID-19.

But with N95 masks in short supply and largely reserved for health-care professionals, a growing number of retailers are advertising KN95 and KF94 masks as alternatives.

These masks—more commonly referred to as respirators in the medical realm—are more effective at filtering out particles in the air, prompting a growing number of experts and public health officials to recommend their use over cloth masks.

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Contrary to some claims on social media, KN95 and KF94 are not “knock off” N95 masks. So, what’s the difference between the two?

SIMILAR LEVELS OF FILTRATION, DIFFERENT FIT

When it comes to respirators, the number associated with the model indicates the filtration efficacy. Both the KN95 and the KF94 mask come very close to the level of filtration found in an N95 mask—they’re simply different equivalents.

The KN95 mask is the Chinese equivalent to the N95, both having 95 per cent filtration efficacy.

The KF94 mask is the Korean equivalent, with a 94 per cent filtration efficiency for filtering out particles 0.3 microns in size, according to Dr. Gerald Evans, chair of Queen's University's infectious diseases division in Kingston, Ont.

“Both of them are thought to be to be equivalent to the N95 that are designated here in North America, and in the 'N' there stands for NIOSH, which is the National Institute of Occupational Safety and Health,” Evans told CTVNews.ca

“The only thing that's really different is that the N95 mask has two elastics that go around your head… the KN95 and KF94 have the ear loops that we’re used to seeing on cloth masks.”

For reference, a regular blue surgical mask has a filtration capacity of about 80 per cent, providing that it’s fitted to the face well without too much gaping at the sides.

But here’s where fit—the most important component—comes in.

While the N95, KN95 and KF94 masks boast high filtration capacities, their efficiency is entirely based on how it fits.

In medical settings, doctors are put through “fit tests” to ensure their mask has a seal. This includes tests like smelling something through the mask (if you can’t smell something you should be able to smell without a mask the seal is working).

Due to the range in shape, size and length of ear loops, not every model of respirator is going to fit properly on every face.

“I do not believe there have been any tests to compare which is better, but the more critical aspect is which provides a better seal around the nose and mouth,” Stephen Hoption Cann, an expert in infectious disease prevention at the University of British Columbia, told CTVNews.ca via email.

“The KN95 is more of a bird’s beak shape vs the KF94 is a little flatter.”

Brian Fleck, professor of mechanical engineering at the University of Alberta, says the effectiveness of masking comes down to basic engineering.

“When a filter isn’t very well fitted… the way pressure and airflow works it goes through the path of least resistance,” Fleck explained over the phone.

“Generally, if the air can find a way around the filter, a lot of it will. So, you can have an extremely effective filter material, but if the air isn’t forced through it, it’s not as effective.”

Fleck notes that a good test when wearing a mask is to put on a pair of glasses—if they fog up when they breathe or come in from outside, the mask isn’t producing a proper seal.

“For people who want to be safe, in other words, they want to reduce the number of particles they breathe in, they should really pay attention to how their mask fits their face,” he said, noting this goes for both medical-grade masks and cloth masks.

“Find the mask where no matter what you’re doing the elastics are tight and it’s not letting any air escape around the edges. Otherwise, you’re really just wearing it for optics.

Hoption Cann says it should be noted that many masks that are sold as KN95 or KF94, when tested, fail to meet their advertised filtration efficacy.

Health Canada, the U.S. Federal Drug Administration (FDA) and the U.S. Center for Disease Control and Prevention (CDC) provide information on authorized products as well as those found to be inadequate.