Protective masks have become a fact of life for millions of Americans in the face of COVID-19 — and with the pandemic spreading at a rapid pace, they’re more important than ever. There are thousands of options available to purchase, including medical-grade N95s reserved for frontline workers, Chinese KN95s and their Korean counterparts KF94s, nonmedical surgical masks, and factory or homemade cloth masks. They often come with claims quantifying how well they filter the air — but they aren’t all the same, and many don’t work as well as advertised. So, how do you know your mask actually works? Aaron Collins, a mechanical engineer specializing in aerosol science, explains.
AARON COLLINS: This mask here, this is a stamped right on it, KN95, and it looks just like this mask here, which has also stamped KN95 GB2626. That’s 2006, which is the test data that they used. I mean, they look nearly identical. This one provided like 99% in mask use. So that’s like filtration efficiency to my face and. all that. This one is about 65%. How would you know as an individual if you didn’t go have the test equipment to know this? How would you know that these are different?
As the information about COVID came out that it might be aerosol, it kind of became evident to me that this is kind of a classic case that you would learn about in sort of your aerosol 101 class with SARS-CoV-1. And I kept finding all these things on Amazon and eBay and kind of random internet searches about face masks. And I started buying them. And I was unsure if they were any good. And my wife was kind of like, why don’t you just test them? Like, isn’t that what you do for a living?
And it dawned on me, like, oh, yeah, I guess I could do that. My background is in aerosol science, with my masters looking at ultrafine particles loss in aerosol diluters. So this really nerdy aerosol kind of apparatus. I did happen to have a lot of that equipment. And so I kind of just kind of started creating this YouTube series where I test a bunch of face masks.
All right, back again for some more mask tests. Today we got a whole slew of tests. I got a whole boxful of about 12 different masks. Filtration efficiency for this mask was 99%. 84.5%. 67.4%, so not much better than this cloth mask. In mask world, there’s kind of two things that we care about. And almost all mask standards are tested for this. One, you need to have good filtration. And it needs to be kind of easy to breathe through. Because at the end of the day, the whole job is like it’s going over your face, so if you can’t breathe while wearing this mask, it really doesn’t do you very good.
The blow test, the flame test, the water test, you’ll see all these kind of weird tests that people try to use today. They’re all meaningless, because I can make a, you can make a face mask meet all those specs and still be fake. And I have real masks that failed that standard. So it doesn’t mean anything. It just means whether a mask can hold water or even blow out a candle while wearing the mask. That’s all it tests.
So if you’re a consumer looking for a protective face mask, the FDA published their Emergency Use Authorization. And they have a list of face mask suppliers that are accepted to them as being of high quality. Outside of that, it gets very difficult. There’s no way of knowing right now. I think it’s hard to say who’s doing a good job and who’s not doing a good job just by their website, because you can make a really cool, very fancy looking website.
So what I always look to do is make sure that if they’re registered for that Emergency Use Authorization Act, and then go straight to an official distributor. They should say, I’m a distributor for this, and they’ll have usually some documentation or some information behind it that’s going to qualify them to know that they’re directly importing from one manufacturer. And that’s specifically in the KN95 space.