By AMERICAN CHEMICAL SOCIETY MAY 5, 2020
The U.S. Centers for Disease Control is recommending that the general public wear cloth face masks to help decrease everyone’s chances of getting COVID-19. So how does the new coronavirus spread? And can a cloth face mask help stop it? Reactions contacted some experts to find out and to learn which materials work best if you’re making your own:
I came across this video recently that shows a person sneezing in slow motion.
Other than thinking ‘that’s disgusting,’ I thought, what if this person was infected with SARS-CoV-2? It could be in all of those droplets and these droplets were traveling more than 20 feet from the person’s mouth.
The CDC is now telling us that cloth masks might cut down on virus transmission, but that wasn’t the original message at first.
We were told not to wear masks.
This wasn’t making any sense. So I reached out to some experts.
One of those experts was Dr. Raina MacIntyre. Dr. MacIntyre is professor of global biosecurity and she studies emerging infectious diseases like Covid-19.
And so the messaging saying that, you know, do not wear a mask in the public. It won’t protect you. It is actually a distorted message that it does not reflect the image or the evidence. And that’s why we’re seeing confusion now because people all over having to backpedal and frantically kind of change their position to be more aligned with the evidence.
The message changed for a couple of reasons. First we’re getting more evidence that people can actually spread the virus without showing symptoms. Second, the CDC didn’t want people hoarding masks and keeping them away from health care workers.
So while I was seeing that the CDC’s messaging changed, I was also seeing this debate about how SARS-CoV-2, which is the virus that causes Covid-19 actually spreads. Some people were saying that the virus mostly spreads via these large droplets that will come out of your mouth when you’re talking or coughing and usually land within six feet of you, which is where that whole six feet apart rule comes from. Other people were saying it’s airborne, meaning this virus hangs out in the air and can travel a lot more than that six feet. Like in the video that I showed you at the top of the episode.
It seemed like there were just these two very distinct options. But Dr. MacIntyre sent me straight.
The idea of respiratory viruses being transmitted by droplet versus airborne is a completely artificial paradigm that is a bit like believing the earth is flat. So it’s a complete nonsense to say, just tell people to stand, you know, three feet or six feet away from other people.
And that this distinction of airborne versus droplet is an artificial distinction based on extremely ancient, antiquated research.
Another expert I called up had something similar to say. Dr. Donald Milton is an environmental health professor who studies airborne infections.
There’s no bright line is on this side, it’s large droplets and and on that, it’s respiratory droplets and this side. So one of the things I’ve been thinking about it, and I’ve seen people starting to use this term and I’m beginning to find it appealing called micro droplets.
The idea that okay, there’s large droplets and then there’s microdroplets and you know there’s a gradient. I think it helped me, help people understand that there’s a gradient. It’s not that there’s aerosols and droplets and they’re two different things. There’s droplets and then there’s smaller droplets.
I asked Dr. Milton how far apart we should actually be standing from each other. And he said there’s no magic number. Six feet is better than being up close, but the further the better.
Not that you’re perfectly safe at seven feet and totally at risk at five feet, but it gets better the farther away you are.
So now that I have a better idea of how this virus can spread, I want to know how much a cloth mask might actually help.
First, here’s how one works. Cloth masks are made of intertwined fibers. SARS-CoV-2 is really small, too small to be trapped by most fabrics that you’d find around your home. Fortunately, it often travels in droplets a lot bigger than that, and cloth masks could help with those.
While some small drops might still get through a cloth mask will help lock the larger ones from breaching our mouths and leaving our mouths.
At this point, there’s no really big controlled study that looks at cloth masks, but what smaller studies have shown for the most part is that cloth masks are better than wearing nothing, and what they’re really doing is stopping those larger droplets.
If you’re planning to buy or make a cloth mask, the CDC is recommending two layers of 100% cotton fabric that’s tightly woven. Think bed sheets with a really high thread count.
As I was doing research, there were a couple of studies in particular that stood out. In 2013, there was a study that tested a virus that was about the size of SARS-CoV-2 against a bunch of different materials.
They looked at things like a hundred percent cotton tee shirts, pillowcases, silk, even vacuum cleaner bags, all do better than if nothing were used.
Antimicrobial pillow cases actually blocked around 68% of the virus, but the vacuum cleaner bags did even better and blocked around 85% or more.
A recent study, which I should mention, has not undergone any sort of rigorous peer review, looked at people’s homemade masks.
They found that two layers of high quality heavyweight quilters cotton with a thread count of 180 or more did the best. That stopped about 79% of the particles from going through. And those particles were a little bit bigger than the SARS-CoV-2, but probably about the size of the droplets that it might travel in.
And double layered masks did better than single layered masks.
If you want to learn more about either of these studies, there are links in the video description.
Another scientist I called up was Dr. Shan Soe-Lin, who’s an expert in global health and she also emphasized the importance of layers.
Use multiple layers.
If you could only have bandanas, use two of those. If you only have a scarf, you know, wrap it around your face a couple times. If you’re using a tee shirt, use two layers of it.
Again, the cloth mask for the general public is really to keep like big globs of stuff away and if you’re social distancing, you should be outside the glob radius anyway.
Good rule of thumb is once you choose a material, hold it up to a light. If a lot of light shines through, if you can even see these fibers here, you should probably choose a different material and make sure that the cloth masks that you either make or buy is really tight to your face. Any sort of space is just going to allow more droplets through.
So again, cloth masks seem to help overall and they help with those bigger droplets. But what if someone needs a lot more protection than that? Like one of our frontline healthcare workers.
That’s where N95s and surgical masks come in.
N95s have multiple layers of material and block 95% of small particles. Some even have a layer with metal ions that will bind to certain viruses like influenza.
But to work correctly an N95 needs to be super tightly sealed to your face. These things are expertly fitted so they’re so tight that they’re even hard to breathe through.
Surgical masks also blocked viruses but are not as effective as an N95 partly because they don’t have that tight seal, not that you can find an N95 or a surgical mask right now.
But if you are like me and not a frontline healthcare worker, you shouldn’t even be trying.
It drives me wild now when I’m in the streets and I see people wearing an N95 mask incorrectly and keeping them away from health workers.
In terms of efficacy, of course N95 better than surgical mask, better than cloth mask. But when you set that against what your actual risk needs are by population, a cloth mask is perfectly fine for the general public.
So I feel like it’s important for me to mention that although most scientists seem on board with cloth masks, there are still some concerns that are circulating.
Dr. Milton brought one of them to my attention.
So you have people wearing masks and they think, Oh, so now I can go up, get close to my buddy and play poker for hours with them. Right? Well, no, that’s not such a good idea.
So there’s this worry that, okay, we’re gonna give people a false sense of security by telling them, okay, wear a mask.
So if you’re going to wear a cloth mask, be smart about it. Part of being smart about it means knowing how to put it on and take it off.
Here’s my mask. It has your loops on the ends here. So what you want to make sure to do is never touch the outside of the mask to your face because that would defeat the purpose of wearing a mask. And this one’s clean.
So you just like put it over your face here and, and put the your lips on here and you can adjust it for like down here if you need to push it pop and then leave alone. Do your thing.
And when you’re taking it off again, like by the ear loops and very carefully move it away from your face. And so I store them like this way, dirty side up.
And so I can, you know, keep putting the same mask on and off if I’m going in and out a couple times a day. And also just make sure that your masks are dry because when they’re wet, they’re not quite as effective.
I wash my masks every night and dry them so that they’re dry for the next morning.
I like to think of it as it’s kind of a triad. So you’ve got social distancing, hand-washing and mask wearing. You need all these three things together because you can’t always hand wash.
If your hands are crusty and touch your face that’s no good. So the mask, you know, kind of protects you against your own dirty hands and the social distancing too the mask can help the fit in that a little bit. Um, if you take a direct sneeze to the face, it’ll help you and all these things are protecting you. If you don’t have a mask, social distancing and hand-washing can help you some, so that’s why we do all three of those things together. That’s the most powerful triadic protection.
In conclusion, if you decide to make a mask, follow CDC guidelines, make the best one possible with this stuff you have, use proper technique to put it on and to take it off and wash it every night. Continue to wash your hands, don’t touch your face. Social distance and self quarantine if you can.
Stay safe, everyone.
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