What are the best materials to make a face mask – to protect against viruses?
Most of the masks were sold out during the coronavirus outbreak, many people will have to be content with this, what scientists say, that it is the "last resort": a handmade mask.
The data shows, hand-made masks effectively catch viruses . But if you are forced to create your own mask, which material is best for making the mask? As the coronavirus spread in China, Internet users reported the creation of masks from tissue paper, kitchen towels, cotton clothes, and sometimes even oranges!
The best material for making a homemade mask.
Scientists at the University of Cambridge have tested a wide variety of homemade materials for making homemade masks. They tested, how well these materials can trap virus-sized particles compared to a surgical mask. They tested materials for Bacillus atrophaeus bacteria (about the size 0,93-1,25 micron) i wirusa Bacteriophage MS (about the size 0,023 micron) in various materials, To see, how they coped.
Nothing unusual, that the surgical mask worked best, catching 97% 1-micron bacteria. However, every single material filtered out at least 50% particles. The best results are with a vacuum cleaner bag (95%), kitchen cloth (83%), blend of cotton shirts (74%) and a cotton shirt 100% (69%).
Home masks versus viruses
Bacteria of the size were used in the test 1 micron, but the coronavirus only has 0,1 micron – ten times less. Can homemade masks catch smaller virus particles?? To answer that question, scientists tested 0,02 micron particles of Bacteriophage MS2 (5 times smaller than the coronavirus).
On average, homemade masks capture Fr. 7% fewer virus particles than larger bacterial particles. However, all home materials managed to catch 50% or more virus particles (except the scarf on 49%).
Are double-layer masks more effective?
If the problem is filtration efficiency, would the masks work better, if we had made two layers? Scientists tested virus-sized particles on two-layer versions of the towel, pillowcases and shirt 100% cotton.
In general, the double layers didn't help much. The double-layer pillowcase captured the same amount of particles, and the double-layer shirt only grasped 2% more particles. However, the extra layer of cloth increased the efficiency by 14%. This made the cloth as effective as the surgical mask.
A towel and a vacuum cleaner bag are the best materials to trap particles. However, scientists have not selected them as the best materials for making masks.
They concluded, that the pillowcase and the T-shirt 100% cotton are best suited for homemade masks. Why?
Importance of antiviral mask breathability
The answer lies in breathability. To, how easy it is to breathe through the mask, is an important factor, which affects the comfort, and thus for the duration of wearing the mask.
Fortunately, in addition to the effectiveness of the particles, researchers tested the pressure drop on each type of fabric. This gives us a good tip, how easy it is to breathe through any material. They then compared the breathability of each DIY mask material to a surgical mask. Auto, what they found:
Although the towel and vacuum cleaner bag captured the most particles, they were also the hardest to breathe. The double-layer towel was more than twice as difficult to breathe as the surgical mask. Whereas a pillowcase, t-shirt, the scarf and sheets were easier to breathe than the surgical mask.
Scientists' choice for the best material for homemade masks
Based on particle capture and breathability, scientists concluded, that cotton t-shirts and pillowcases are the best choice for homemade masks.