Updated: Apr 7, 2021
As we come to our first full year of the COVID-19 pandemic more and more companies are offering masks, from fast fashion brands to high end fashion houses. Here is a breakdown of the different fabrics companies use and which ones are best for respiratory protection.
If anyone is reading this and thinks masks do not work please click here to read an article about why they do. I would never cut into a patient without wearing a mask for both their safety and mine so let that be your guiding principle.
Enjoy this read and, as always, click the numbers in square brackets to check out all the references!
Reusable vs. Single Use Masks
There are a number of reasons to buy reusable masks for your day-to-day mouth and nose coverage needs. I’m sure many people have seen the awful images of beaches covered in single use face masks thrown on the ground. The environmental impact of these masks has been terrible on wildlife [ii,iii] so if you are wearing them throw them directly in the garbage in a way they cannot fall out or blow away. Also please consider switching to reusable masks for short excursions or errands.
Another issue is that certain places are still experiencing medical mask shortages for healthcare and front line workers [iv]. If you live in one of these areas and are not one of these workers please do not buy and hoard masks that you will only use to go get groceries.
Both single use and reusable masks are effective at stopping you from spreading the virus as they catch the little water droplets that you exhale which contain the virus [v]. It is important to clarify that ‘dry’ virus particles floating around are not trapped by fabric or procedure masks very well.
The reason reusable masks are still useful is because they do a good job blocking virus particles trapped in water which is how our bodies release the virus out of our mouths and noses. Small exhaled water droplets are an important way that COVID-19 is transmitted [vi].
Respirator masks, like the N95, are the most effective type of mask when trying to reduce the inhalation of anything aerosolized, like viruses [vii]. That said, they are the most expensive, they have a negative environmental impact, you may not even be able to buy them right now, and for most day to day activities cloth masks work well so you don't need to be wearing an N95.
Silk has been shown to be a great material for reusable masks [viii]. It is a hydrophobic fabric meaning that it repels water droplets instead of absorbing them. That’s why if you’ve ever spilled something on a silk shirt or scarf you’ll notice little beads of water that roll off. Because it is a relatively breathable fabric it doesn’t contain the moisture around your mouth as you breathe. This is good because a warm moist environment is an easy place for bacteria to grow.
Silk makes a great inner layer of your mask that sits against your face.
Cotton is a very common material used for masks, for both this outbreak and previous ones like the 1918 flu [ix] and the Manchurian plague [x]. When the fabric is made with a tight weave (high thread count) it can stop a significant number of particles from passing through [xi]. An issue with cotton is that it is hydrophilic so it absorbs water instead of repelling it. This means that over time it can create a little pool of virus particles stuck in the mask [xii].
Soft cotton makes a decent inner layer of your mask against your skin but it makes a much better middle or outer layer.
I was not able to find any research that specifically looked at linen’s properties. A clear benefit is that it is a natural fibre that is highly breathable, which is why it is so comfortable to wear in the summer [xiii]. Unfortunately it is loosely woven so would not trap particles very well and like cotton it is hydrophilic and absorbs water instead of wicking it away [xiv].
Linen does not have great properties to be a layer of your mask.
Because it is a synthetic material, there is a big variation in polyester material properties like hydrophobicity and weave. Generally speaking if the fabric is designed to be hydrophobic (water repelling) and tightly woven it can be a useful option [xv]. The problem with polyester is that it is not breathable. This means that you can create a warm and humid closed space around your mouth where bacteria may grow and make viral spread easier [xvi]. Polyester material can also bother people with sensitive skin [xvii]. Fleece is a polyester fabric that you might find used as a layer.
Polyester material makes a good outer or middle layer of your mask. It can be used as an inner layer as long as it is a polyester blend made with a natural breathable fibre, like polycotton.
Like linen, I couldn’t find research specific to wool fiber used as a mask. However, wool is naturally moisture regulating and quick drying [xviii] so it won’t create a humid area around your mouth. Wool can be tightly woven like cotton which can reduce viral spread. Wool is highly absorbent without feeling wet [xix] which makes it comfortable but definitely means you need to wash it between uses. However, a benefit of that absorbency is that it can stay warm when you are somewhere cool and stay cool when you are somewhere warm (click here for a good explanation on how that works).
Wool deserves more research because based on its intrinsic properties it’s a good fabric! It would make a good middle layer or inside layer against your face.
The Ideal Mask
Based on my research the ideal mask has an outer polyester or polycotton layer, a middle layer of cotton, wool, or silk, and an inner layer of wool or silk. It is best if every layer is different to get the most out of each of them!
If you cannot get a mask with the 'ideal' layers, a good option is to buy one with a thicker removable filter. This means you can add more protection to your face [xx].
It is important to buy a mask that has layers made from different fabrics. ‘Hybrid’ masks have the best filtration rates because they work synergistically. This means you get the best of all the fabric types.
Always make sure your mask is covering BOTH your nose and mouth and that it is the right size and correctly fitted to your face. This will help stop anything you breathe out from leaking without having been filtered by the mask. A poorly fitted mask can decrease the filtered air by more than 60% [xxi]!
Wash your mask with hot water and soap after every use!
I am guilty of using my mask multiple times before washing it, don’t be like me!
Reducing transmission works best when everyone who can wear masks does so, when people wash their hands frequently and for long enough (30 seconds), and when we maintain social distancing especially indoors [xxii].
Remember, mask shopping is like bra shopping, you want the right fit, a good design, and layers that wick away moisture while staying breathable.
That said, using a bra AS a mask is a bad idea and does not work.
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