KN95s (masks claiming to meet Chinese standards) and KF94s (those claiming to meet South Korean standards) require similar filtration efficiency to N95s but not the same markings, and so they can be tougher to evaluate by sight.

When shopping online and in stores, consumers are most likely to find the international equivalents of the coveted N95, as these masks are still generally not available in stores.

When used by healthcare workers, surgical and P2 masks are supposed to be thrown away after a single use. Now add another player to the mix – the KF94. This mask has been getting increasing buzz these days, with at least one media outlet calling it a "highly protective" option to look into at a time when emerging coronavirus variants appear to be more contagious. If you walk into a coffee shop for two minutes on your way to work with a brand-new N95 on, do you need to throw it out and use a new one when you arrive? Not exactly. As for the masks that came in just a percentage point or two below the standard, he said they can still be used. The best way to find legitimate masks is to buy ones made by reputable manufacturers and sold by trusted retailers. (In our guide to N95, KN95, and surgical-style masks, we explain how to do that, and we recommend specific masks that have passed government tests or independent lab tests to confirm their filtration efficacy.) But sometimes you end up with a pile of masks of dubious provenance, courtesy of your workplace or a well-meaning relative. Or you might be tempted by a good deal from a brand you haven’t heard of. Or maybe you have little choice but to buy whatever is on the drugstore shelf.

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.” It’s very important that with Omicron – it’s just so transmissible – that people wear the best quality mask they can,” said Dr Karina Powers, an occupational health physician in Western Australia. Our study had certain limitations. First, we used only three KF94 types with ear loops of different shapes; thus, these may not be representative of all KF94 masks or all ear-loop-type masks, and there is a limit to generalize the results. Furthermore, although KF94 masks with filtration efficiency certified by the KFDA were used, comparison with N95 or EU FFP2 was not carried out. Thus, it is difficult to draw conclusions regarding the effectiveness of respiratory protection compared to that of these masks. Second, the total FF of QNFT was measured only once according to the wearing method for each mask per participant. Even if the participants wear the same mask, in the same way, the FF may change for each test, limiting the interpretation of the results due to the single-measure design. Third, QNFT was conducted according to the OSHA protocol consisting of some activities, which might differ from the actual clinical activities. Moreover, the QNFT conducted within 3 min cannot guarantee whether the protective effect will be maintained during prolonged use. Forth, after general-fitting QNFT measurement of each mask, masks were not changed during tight-fitting QNFT measurement, which may have affected the results. However, the FFs of the tight-fitting method were significantly higher in all measurements for every mask type, thus it does not seem to be a meaningful change. Fifth, in addition to the wearing method, we did not consider related factors, such as face size and presence of a beard, that interfere with mask fitting. Sixth, we did not assess the user experience of KF94 masks according to the wearing methods and mask types. Finally, we did not consider the expediency and infection risk associated with the donning and doffing of masks.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. The very best disposable face masks are N95 masks, approved by the National Institute for Occupational Safety and Health (NIOSH), as they filter out 95 percent of airborne particles. They’re especially good for high-risk occasions, like spending a long period of time in a crowded enclosed space. Imported KN95 masks, the Chinese-made equivalent to the N95, are also a popular disposable option. Yi Cui, a professor of materials science and engineering at Stanford University who co-authored a study on the efficiency of various mask materials, says the certification processes for KN95 and N95 masks are “nearly identical.” The main difference is their shape and the fact that many of the KN95 masks on the market today are unfortunately counterfeit. Most of the rest of what you’ll see on the market are KF94 masks, the South Korean equivalent of an N95 mask, and pleated disposable masks. Kullar says the “94” indicates a 94 percent filtration efficacy. Though that might make it sound like they’re less effective than KN95 or N95 masks, which are purported to have 95 percent filtration efficacy, the truth is more complicated. Because there hasn’t been any official head-to-head testing between the two, the deciding factor on which one is better at protecting you comes down to which one fits your particular face better.