You’ve heard of N95 and KN95 masks – but have you heard of KF94 and what’s the difference between the three?
There are many high quality masks on the market with different letters and numbers. Understandably, this can be confusing. In order to decipher their differences and how each one works, there must be an understanding of what the different letters and numbers represent.
“The number of all of these refers to the effectiveness of filtering, so the percentage of articles it stops penetrating,” says Dr. John Volkens, a professor of mechanical engineering at Colorado State University.
KN95 filters 95% of the particles, as does N95. KF94 filters 94% of the particles. The difference between the letters is the certification of the state standard.
“N in N95 means NIOSH [The National Institute for Occupational Safety and Health]and that̵
“N” is also a NIOSH rating for masks that are not oil resistant.
KF literally means “Korean filter”. In particular, a study published in 2020 showed that KF94 masks were comparable to N95 in blocking SARS-CoV-2 particles and were more effective than a surgical mask. However, the study was quite limited, as only seven patients with SARS-CoV-2 infection were included.
“KF94 seems to be more easily available than the N95, cheaper [generally under $2 each] and easier to use for many people, “Sonali Advani, an assistant professor at Duke University, told NPR. KF94 is actually intended for public use. In Korea, they are often worn by ordinary citizens to filter out dust or dirt. “
Volkens explained that the N95 masks are certified by only one laboratory that is part of the Centers for Disease Control and Prevention (CDC), and this is partly why supply cannot meet demand at the moment.
“They’re very strict about who they let become the N95, so you don’t see a lot of them on the market anymore because they’re all bought,” Volkens said. “The problem with KN95 and KN94s is that there are a lot of impostors on the market and we don’t know what you’re buying.”
As for the N95 masks, each mask has a stamp stating that it is NIOSH certified with a certification number that you can search online. Volckens added that there are also masks that have ASTM [American Society for Testing and Materials] standards that are “almost equivalent” to N95 masks – such as FFP2, which means “two-level filter mask”.
In some parts of Europe, such as Germany, the federal and provincial governments are forcing FFP2 masks to be used in shops and on public transport now. According to NPR, Austria makes similar recommendations. In France, the Supreme Council of Public Health announced that it also recommends that people wear surgical masks in public instead of cloth masks.
In the United States, the CDC continues to recommend fabric masks to the general public, as long as they have at least two coats.
Volckens said that if you buy a fabric mask, you should look for three key features: fit, filtration and breathability.
“The filtering ability of the tissue, you want a high-performance filter, you want a fit – and that’s personal, but you want to make the mask fit snugly all over your face and then breathe, you have to be able to breathe normally through the mask,” Wolkens said. “Otherwise, if it’s uncomfortable to breathe, you won’t wear it and it can be dangerous.”
Of course, it is difficult to understand what the mask is until it is purchased. But Volckens said people should buy masks from a supplier who has been tested with filters. As for the fit of the mask, this can be reconciled by double masking.
“That’s why you can double a mask, because you can buy a mask that doesn’t fit well, but then use something else to hold that mask closer to your face,” Volkens said. “That’s what we’re talking about, that double masking is effective in the right form.”