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The evolving science of masks

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How can you tell if the mask you’re wearing is protective enough against the coronavirus? Correspondent David Pogue volunteers as a test subject to see how N95s work and learns about the science of face coverings.

Video Transcript

JANE PAULEY: One year of COVID and counting, one year of wondering which face mask is best. As we begin our look back at this very difficult time, that's where David Pogue starts us off.

DAVID POGUE: Man, I've still got a lot of questions about these masks. I mean, I can still remember when the advice was not to wear one.

MICHAEL RYAN: We don't generally recommend the wearing of masks.

DAVID POGUE: And now they say we're supposed to wear two? But which is better, this kind or this kind? N95? KN95? Who's testing these things, and why do they keep changing their minds?

JAMES DICKERSON: So I would argue that it's not changing one's mind. Knowledge changes that is actually a fundamental component of science.

DAVID POGUE: James Dickerson is the chief scientific officer for Consumer Reports, and by happy coincidence, a nanoscientist. There aren't any standards for testing masks like these, so the magazine doesn't test them, but Dickerson offered me a little mask show and tell. Well, welcome to the Home Shopping Network for masks.


DAVID POGUE: This I recognize as a gaiter.

JAMES DICKERSON: Stay away. My advice, Consumer Reports' advice, stay away from them.

DAVID POGUE: What about these cloth masks?

JAMES DICKERSON: So many cloth masks are OK. More layers, more protection, both for you, and for others.

DAVID POGUE: Some of them I've seen have these little exhaust fan things, exhaust filters.

JAMES DICKERSON: Yeah, bad idea because most of the vents do not filter the air coming out from your breath directly to the outside.


JAMES DICKERSON: Those are not protective for others.

DAVID POGUE: Now here we come to the paper surgical masks.

JAMES DICKERSON: Yep, they're perfectly fine. In fact, they're really good to use in combination with other masks. For example, you can use a surgical mask with a cloth mask.

DAVID POGUE: Now we've all heard about these N95 masks.

JAMES DICKERSON: So the 95 is 95% of airborne particles are captured by the mask.

DAVID POGUE: These are also N95? It looks totally different from these bra cups.

JAMES DICKERSON: So that one is a KN95. KN95 is based on the Chinese standard. The standards are very similar to each other.

DAVID POGUE: As it turns out, you can test your own mask with your phone's flashlight. If you see light between the threads, that's not much protection. Oh my gosh, I could--


DAVID POGUE: I could count the threads. Let's try one of these puppies.

JAMES DICKERSON: See, in this case, you don't see any specific dots of light, you see the glow of the fabric.


JAMES DICKERSON: So that's more protective.

NICOLE VAR MCCULLOUGH: So in 2019, we were making about 22 million N95s here in the United States a month. We are now in the US making more than 95 million a month.

DAVID POGUE: Nikki Vars McCullough, is an engineering manager at 3M. That's right, 3M, maker of Post-It Notes and Scotch tape, also happens to be the nation's largest producer of N95 masks. Well, actually I shouldn't say masks. I think of these as two different kinds of masks but you kind of wince when I say that don't you?

NICOLE VAR MCCULLOUGH: I do. Because they are really different. The one with the ear loops there that you're holding, yep, that is a face covering. So if any particles come out, if you're coughing or sneezing, or you're talking and it's kind of spitty, it'll catch it.

DAVID POGUE: I notice that you're not saying very much about them protecting me from incoming virus.

NICOLE VAR MCCULLOUGH: When you put something on that has any gaps, any gaps around the edges, the air and the particles are just going to take the path of least resistance.

DAVID POGUE: Now this on the other hand, you don't call this a mask?

NICOLE VAR MCCULLOUGH: No, that is a respirator. A respirator is designed to a specific government standard to help reduce the particles that you breathe into your nose, mouth, and lung.

DAVID POGUE: This is two-way, this stops incoming and outgoing?

NICOLE VAR MCCULLOUGH: That is correct. And I wouldn't say stop, it filters.

DAVID POGUE: It sounds like fit is a big deal.

NICOLE VAR MCCULLOUGH: Fit is a very important detail. This hair is 20 microns in diameter and we're talking about particles that are half a micron. I want to welcome you to the global fit test laboratory.

DAVID POGUE: McCullough took me to the 3M human fit labs to cut open an N95.

NICOLE VAR MCCULLOUGH: On the outside we always have a layer that's protective and then you start to get into the filter media, the layers that actually do the filtering.

DAVID POGUE: The virus particles don't just get physically blocked, they're also attracted to the fibers thanks to a tiny electrical charge. 3M tests its N95 models in this special chamber.


DAVID POGUE: At this performance, the role of test subject will be played by me. If I'm not back in four hours, call the police. The air in there is flooded with microscopic particles of harmless salt. A tube near my face measures how much salty air is leaking in.

-- Begin bending at your waist. Begin grimacing for 15 seconds.

DAVID POGUE: You're supposed to move around in ways that might dislodge the N95.

-- Begin turning your head side to side.

DAVID POGUE: I feel salty and invigorated.

NICOLE VAR MCCULLOUGH: We watched you, you did a great grimace, see the change, the two--

DAVID POGUE: When this graph spikes something went wrong. Oh, yeah, so here's where the mask slipped off my nose.

NICOLE VAR MCCULLOUGH: Yep. But at the tail it was back to fitting really well.

DAVID POGUE: A couple more things about these N95s. First of all, officially you're still not supposed to buy them, because medical workers still can't get enough. Second, beware of counterfeits. The CDC says that most authentic N95s have the word NIOSH stamped right on the outside, meaning that it's been certified by the National Institute for Occupational Safety and Health.

Oh, and read the reviews before you buy. I'm aware that the science is evolving is there anything concrete and for sure you can send us off into the sunset, information you don't think will be changing?

JAMES DICKERSON: Wearing a mask is better than not wearing a mask at this stage. Wear as dense of a mask as you feel comfortable. So wear a mask, wear a mask, wear a mask.