Our two cents about masks

There has been a lot of talk about masks lately, culminating in last Friday’s recommendation from the CDC that we all wear fabric masks when we are in places where social distancing is difficult – “especially in areas of significant community-based transmission.”

I, myself, had questions about precisely how to make fabric masks, so I enlisted my friend and colleague Virginia Lanzotti, who started making masks weeks before the CDC recommendation, to co-authoring this post with me.  I’ll let her introduce herself:

Unlike myself, many of my closest friends don’t have the luxury of working from home. They are ER physicians, ICU nurses, nurse anesthetists and nursing assistants who are working face-to-face with COVID patients amidst a global shortage of PPE. These friends were picking up home-made fabric masks from my porch on their way to work weeks before the CDC’s announcement promoting cloth mask-wearing in public spaces in hopes of prolonging the life of the solitary N95 respirator they had been issued for the day.

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(Note: if you just want to skip to the bottom line, scroll down to the end of the post.)

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Alexis: In case readers aren’t sure what an N95 respirator is, they can go to this website from the Johns Hopkins University Bloomberg School of Public Health for a great description of the different types of masks that people have been talking about with regard to COVID-19 and other viruses that are thought to be transmitted primarily through tiny droplets that are sneezed, coughed or otherwise exhaled by people with the infection.  These are N95 respirators, surgical masks, and fabric masks. Right now the WHO recommends that sick people wear surgical masks and the people caring for them wear N95 respirators. Why isn’t it recommended that everyone just wear N95 respirators?  It is my understanding that it is impractical to recommend that members of the general public wear N95 respirators whenever they are out and about. This is because the general public doesn’t typically need this level of protection – especially if they are staying an appropriate “social distance.”  In addition, I’m told that properly fitted N95 respirators are uncomfortable and difficult to breathe through, which means that people tend not to use them consistently and properly. If they aren’t used consistently and properly, they aren’t going to be very effective.  

Virginia: Yes, wearing an N95 when fitted correctly can quickly make you feel light-headed and not be able to think as clearly. It’s not the kind of thing you want to keep on any longer than necessary. This is because it is designed to form such a good seal that only a tiny amount of air is entering or escaping around the edges of the mask. Over time, you end up rebreathing your own CO2 which in turn makes you feel short of breath. Everyone’s instinct is to grab that mask and pull it down to get a breath of fresh air, and therein lies the problem. As soon as you touch the front of the mask, you’ve just contaminated your hands with whatever was on the outside of the mask. Even if you remember to remove it by the straps, N95’s are designed for single use, and cannot be washed and reused like a cloth mask can, so they really don’t make sense in low risk situations.

Alexis: Surgical masks are more comfortable to wear, but otherwise the same drawbacks apply as for N95’s. If you’ve been following the news, you may also have noticed that experts haven’t been in complete agreement about whether the general public should be advised to wear surgical masks. Some argue that surgical masks don’t do a very good job of protecting people from contracting viruses like influenza and COVID-19 because they don’t fit tightly on the sides, which allows the smaller droplets to get past.  In addition, it is argued that wearing masks might cause people to think they are more protected than they actually are and therefore be less likely to engage in other protective measures such as social distancing, frequent and thorough hand washing, and trying not to touch their faces. On the other hand, people in favor of wearing masks argue that if people wear surgical masks they will be less likely to touch their faces because the mask will make them more aware of doing so.  Further, although the finer droplets might be able to get around surgical masks, it is thought that they should still block some droplets – and results from a study published just the other day suggest that they might even reduce aerosols. 

But protecting oneself from getting the virus isn’t the only reason to wear a mask. We also might want to wear a mask to protect others from getting the virus from us! Remember the WHO recommendation that sick people wear surgical masks? Since we now are pretty sure that people with COVID-19 are contagious before they show symptoms (see, e.g., this article), everyone is potentially contagious, even if we don’t have symptoms.  This is the rationale behind the recommendation that all people wear masks when out in public: we aren’t protecting ourselves, we are protecting others.  We should also note here that if wearing masks to protect others leads to fewer cases of COVID-19 in our communities, then we are also protecting ourselves and our loved ones – albeit indirectly.  

The problem is that there is a worldwide shortage of personal protective equipment (PPE), including N95 respirators and surgical masks, and we need to leave those for healthcare workers. This is why the CDC has recommended that people wear fabric masks.  This leads us to the question of whether fabric masks work as well as surgical masks – or at all.  

Virginia: Well that really depends on what kind of fabric mask you are referring to. A simple two-layered  cotton mask like a bandana, let’s face it, is kind of like going into battle with an armed opponent when all you have is a handful of rocks in your pocket. Most woven cotton that you find in a fabric store, when you hold it up to the light, if fairly transparent. With COVID, we are talking about viral particles that are 1 micron–A thousandth of a millimeter–in size. A single hair from your head, to put it in perspective, is around 100 microns thick. Two layers of cotton are better than one, but only just. Without getting ridiculously technical  (remember, I’m not claiming to be a textile expert) suffice it to say that the more tightly woven the cotton, the better, and the more layers of cotton, the less that gets through.The other thing that makes a difference is how well the mask fits. I’d venture to say that when you compare a well-fitted cloth mask with filter material inserted, it would actually perform better than a disposable surgical mask. “Aha!” You say, that’s where you’re wrong! I saw a study that said cloth masks are inferior to surgical masks!” Oh, you mean this one? Yeah, I saw that one too. But that study compared 2 LAYER cotton masks to surgical masks. And this, my friends, is a very important difference to note. I have a surgical mask which I used as a starting point for prototyping my fabric mask. It’s comfortable enough and easy to breathe through, but it gapes at the cheeks and chin, and it’s paper, so you can’t wash it. The masks I’ve designed have an adjustable head strap to eliminate gaping at the cheeks, wire at the nose and jaw to help mold them to the face, and with the filter inserted are 10 layers thick.  Those stones in your pocket now have a sling-shot to go with them. Make sense? 

Alexis: Okay, so what do I make my mask out of?

The masks that I am making for my family, friends, colleagues and well, pretty much anyone who asks, are made from high quality quilting cotton, designed with a filter pocket that allows the user to add additional layers of filter material beyond the two inner and outermost layers.

These are unprecedented times, and even fabric stores have shuttered in a lot of places. If you aren’t lucky enough to have access to high quality quilting cotton, don’t despair. You can always cut up old sheets or other cotton garments that are begging to be repurposed. Just remember to pre-wash and dry your fabric before you sew it to ensure it’s preshrunk.

Alexis: What have you been using for the filters? 

Virginia: Think of filtration and breathability as two opposite ends of a spectrum. At one end, you block out 100% of particles but the material is so impenetrable that you can’t breath through it. At the other end you can breathe easily but pretty much everything is getting through. So we try to find the optimal balance between the two, and also we try to keep things practical because most of us don’t have access to all kinds of specialized textiles, nor are we excited by the prospect of getting out in the COVID-infested world to procure them (OK I’m being dramatic, but you get the point). There are many options out there for filter materials–vacuum bags, furnace filters, paper towels, and if you’d like to see a comparison for yourself, I would encourage you to look here. 

I’ve been using 8 layers of cotton, alternating the grain. “Why” you ask? I’d like to be able to say “Because after consulting several head-to-head studies comparing filter materials…” only those studies were never done because frankly, no one had a reason to care back when N95’s were plentiful and Corona was just a beer. Sorry to disappoint all the legitimate scientists and meta-analysis junkies who may be reading this, but I don’t have all the evidence I wish I did to justify why I am making my masks the way that I am. But before you go rolling your eyes and assuming that there is no credible basis for what I’m saying, hear me out for a second. Back in 2005, some forward thinking individuals experimented with making a mask from materials that most people would have on-hand in the event that commercial masks were to become unavailable. They shared their findings with the CDC: and it was there that I came across the recommendation to use layers of cotton for the filter. Back then the threat was H5N1, a pneumonia causing avian flu, and they used Hanes- t-shirts to make masks for health-care workers and members of the military residing in barracks. The takeaway from this simple but relevant study, is that by simply increasing the number of layers of fabrics, the masks were able to block significantly more viral particles from getting through. They suggested 8 layers of fabric, alternating the grain–so that my friends, is what I have been using, and where that idea came from.  

Alexis: That makes sense, but can you breathe through all that? 

Yes! I can say I’ve worn these out to run errands several times in the past few weeks and could definitely breathe comfortably. An additional merit of a cotton filter is that it can be washed and/or boiled over and over and over again, which makes a lot of sense given that this situation may last longer than any of us would like to imagine and the current shortage of many single-use materials.

Alexis: Okay, so I know what to use for the mask and the filter, now I need a pattern. There are so many out there – it’s overwhelming!

Virginia: Regarding the overall design of the mask–there are some beautiful, very professional looking mask patterns out there that I would encourage you to check out and try, such as this one. Please just do yourself a favor and take the time to find a pattern or tutorial for a mask that includes a filter pocket, as many are simple two layer designs. I know myself well enough to know that I lack the patience to trace out a pattern for every single mask and painstakingly cut every single one along the lines–especially knowing  that my lovingly made mask may very well end up in a waste-basket after one use. That’s just me, and if you’re making a smaller number, it might well be worth the time. I also wanted to be able to maximize production capacity, so I’ve chosen to work off of this tutorial, which requires no pattern and can be made by a child with minimal assistance  After prototyping a few of these, I found them a bit small, so I have made the following modifications which I’ve listed below.

• Outer Fabric dimension: 10 in x 10 in (1 piece)
• Inner Fabric dimension: 8.5 in wide by 6 in height (2 pieces)
• Add: Wire at nose and jaw.
• Add: 8 layers of cotton for filter insert (doesn’t need to be sewn)
• Swap: Adjustable head strap instead of earloops. 40 inches of paracord, cotton, ribbon, whatever you have. 

So there you have it! I make no claims of having the best design out there and welcome suggestions of how to improve from here. Many resourceful and innovative people have devised all kinds of ways to make good masks using what they have on hand. I came up with this design after making a lot of less-than-professional looking masks, and after my first choice materials went out of stock. Please feel free to let me know what has worked for you–I’m always happy for the opportunity to learn and improve. 

Alexis: Thanks, Virginia!  

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The Bottom Line – Alexis and Virginia’s read of the evidence regarding masks