Coronavirus Special Coverage

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FDA keeps changing KN95 guidelines, so stick to N95s or cloth masks

Earlier this year, with N95 respirators in short supply, the US Food and Drug Administration (FDA) issued emergency authorizations for Chinese-made KN95 respirators. New manufacturers soon flooded the market, unfortunately with often-defective products that the FDA signed off on anyway. Now, according to a new report from the Wall Street Journal (archive link), states that trusted the FDA information and stocked up on KN95 masks are struggling with how to respond.

Here’s what you need to know:

  • The FDA maintains a list of approved KN95 masks, but that list may not be reliable. Some masks have been listed there and then removed later.
  • The FDA recommends using an actual N95 respirator if available, only using KN95 masks if no other option is available.
  • The most reliable respirators use head straps and not ear loops.
  • Even an unreliable mask is probably better than nothing, as long as you don’t treat a mask like an invisibility cloak.

N95 vs KN95

An N95 respirator is different from a typical cloth face mask or surgical mask because it’s certified to remove at least 95 percent of airborne particles. While a cloth mask traps your spittle and sneezes so they can’t travel through the air and infect someone else, N95 masks also protect you from even the most minuscule particles. As such, these masks also need to seal tightly to your face, making it necessary to shave if you have whiskers.

In theory, a KN95 mask is just as good as an N95. The difference between an N95 and KN95 actually comes down to something as simple as where they’re certified. In the United States, N95 respirators are certified by the National Institute for Occupational Safety and Health (NIOSH). KN95 masks are certified in China. Different countries have different names for the certification. So in Japan, the same sort of mask might be sold as a DS2 and in Europe an FFP2, all with somewhat variable standards. Similar masks, different names.

It’s important to understand that the respirator designation is a reflection of where the mask was certified, not where it was manufactured. Many N95 masks are produced in China but are tested to comply with strict American standards.

What went wrong

In short, the rush to get protective masks on the market caused a complete regulatory system failure. The FDA was stuck between a rock and a hard place—the urgent need for PPE and the slow process of properly regulating that protective equipment. Two forces were at work:

  1. Healthcare workers were begging for personal protective equipment they needed to treat the growing pandemic safely.
  2. The FDA slowed things down with safety regulations and resisted approving the import of Chinese-certified masks for this reason.

In April, the FDA finally caved and approved the import of Chinese-certified KN95s.

Meanwhile, in China, over 3,500 new respirator manufacturers had popped up almost overnight. One-fifth of the 85 manufacturers approved by the FDA were just a few weeks old. By now, more than 60% of imported masks, almost entirely from China, have failed basic American quality tests.

The lack of quality in the rush to market shouldn’t surprise anyone, especially not regular readers of The Prepared. Jon Stokes warned about buying random masks from the internet back in June. The real failure came from the FDA’s push to get masks out.

The FDA maintains a list of approved KN95 respirators. Unfortunately, many of those defective masks made it to the list without proper vetting. After approving 85 KN95 manufacturers in April, the FDA slashed 71 of those from the list the following month.

Unfortunately, it was too late for many states and medical facilities, which spent millions of dollars on masks of questionable quality, and are now stuck with warehouses full of them.

What you should do

Personally, I wouldn’t spend money on a KN95 mask. In one NIOSH test, a KN95 only filtered 32% of airborne particles, though that’s a worst-case scenario and many performed much better. Remember, a KN95 is supposed to filter 95% of particles, so that test really fell short. Another issue pointed out by the Wall Street Journal: while reputable N95 masks are secured with head straps, most KN95 masks only use ear loops. That means they can’t provide quite as good of a good seal.

I’d like to say that you could look at the FDA’s list of approved KN95 respirators as you decide what to buy for protection. But while I’m sure that list is much improved, I’m still wary of it. I do see one brand I trust on that list, 3M, but I can’t find any of their KN95 masks for sale anywhere.

The reality is, for general going-out-in-public purposes, a surgical mask will probably be as good as anything. A surgical mask blocks about 75% of particles, which isn’t as good as an authentic N95, but is much better than the poor-performing KN95 above.

“Uncle Rob” made a fun video using an improvised flamethrower to show the efficacy of a regular surgical mask. (Spoiler alert: the mask worked better than he expected it to.)


You could also make your own mask. One study showed that a mask made out of an old prom dress can be just as effective as an N95. Cloth masks are estimated to block between 30-50% of particles, so in a worst-case scenario, you’re no worse off than you’d be with a bad KN95. You’d also have more money in your pocket.

If you already have a stockpile of KN95 masks, you might as well wear them. They may not be as effective as advertised, but they’re probably at least as effective as a plain cloth mask. Of course, make sure you get the best possible seal, and if the mask smells musty, toss it.

More: Have an Instant Pot? DHS says you can use it to decontaminate an N95

Are masks worth the bother?

The mishandling and mixed messaging behind masks has led to a great deal of fear, uncertainty, and doubt about their effectiveness, which is perfectly understandable. Like most things in American life, masks have become a contentious political subject.

Do what you will within the bounds of the law and the rules of the establishment you’re in, but the reality is that like many things we recommend here at The Prepared, masks are a tool. All the available evidence indicates that masks are effective at limiting the spread of COVID-19. We have no horse in that race other than to keep you safe and slow the rate of SARS-CoV-2 transmission.

While masks have been shown to reduce the range of water droplets that carry the SARS-CoV-2 virus, they are not a substitute for social distancing, especially since droplets can still spread several feet with some masks. Dr. Anthony Fauci has recently suggested that goggles or face shields could improve the efficacy of face masks, an idea Stephanie Arnold reported on last month.

Like any piece of protective gear, masks have their limits. Just because you’re wearing a plate carrier doesn’t mean you want to get shot, nor would you want to drop an anvil on your foot if you were wearing steel-toed boots. Stay at home if you can, and keep your distance when you can’t — mask or not.


    • DaveH

      Josh, Any chance we could get an update on masks soon? The recent news about more contagious mutations has prompted me to do some mask shopping and after getting confused and frustrated I thought I’d check back in on my favorite review site, The Prepared. Have you learned anything about kn95 since this article? Can we expect manufacturers to deliver p100 or n95 masks any time soon? Thanks very much.

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      • Josh CentersContributor DaveH

        Thanks for asking. I’m working on a mask-related post now. I still would not trust KN95s, but I need to do some more research there. I’m sure some manufacturers are more reliable than others. I recently placed an order for N95s with United States Mask out of Texas, but they are currently out of stock (sorry, that’s partially my fault).

        It’s looking as though valved respirators may not be as bad as once thought, and they can be effectively sealed from the inside with ECG pads or surgical tape. Failing that, surgical masks are the next-best thing.

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      • DaveH Josh Centers

        Thanks Josh

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