While the public has been urged by the CDC to make their own masks and wear them in public, we in recent times have learned something new about cloth masks. Sure, the surgical and N95 masks during this pandemic need to go to those who work in the medical world but what kind of cloth should you be making your homemade masks out of?

According to a new paper published in ACS NANO, titled ‘Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks.’ The team of researchers working on this study looked at lots of different kinds of fabrics and their filtration abilities. They checked out things like cotton, silk, flannel, various synthetics, chiffon, and even a combination of different kinds of materials altogether. Apparently, they were able to come to the conclusion that when properly used and fitted correctly using multiple layers and mixing up fabrics worked best at filtering out different particles.

Personally, for my homemade masks, I used cotton for inside and outside layers with a layer of Flannel within. For this research, those who worked on the study set up an experimental environment in which the team used an aerosol mixing chamber to really get deep into testing these fabrics. Particles were passed through tubes that had these fabrics secured on the end of them.

The abstract of this study goes as follows:

The emergence of a pandemic affecting the respiratory system can result in a significant demand for face masks. This includes the use of cloth masks by large sections of the public, as can be seen during the current global spread of COVID-19. However, there is limited knowledge available on the performance of various commonly available fabrics used in cloth masks. Importantly, there is a need to evaluate filtration efficiencies as a function of aerosol particulate sizes in the 10 nm to 10 μm range, which is particularly relevant for respiratory virus transmission. We have carried out these studies for several common fabrics including cotton, silk, chiffon, flannel, various synthetics, and their combinations. Although the filtration efficiencies for various fabrics when a single layer was used ranged from 5 to 80% and 5 to 95% for particle sizes of <300 nm and >300 nm, respectively, the efficiencies improved when multiple layers were used and when using a specific combination of different fabrics. Filtration efficiencies of the hybrids (such as cotton–silk, cotton–chiffon, cotton–flannel) was >80% (for particles <300 nm) and >90% (for particles >300 nm). We speculate that the enhanced performance of the hybrids is likely due to the combined effect of mechanical and electrostatic-based filtration. Cotton, the most widely used material for cloth masks performs better at higher weave densities (i.e., thread count) and can make a significant difference in filtration efficiencies. Our studies also imply that gaps (as caused by an improper fit of the mask) can result in over a 60% decrease in the filtration efficiency, implying the need for future cloth mask design studies to take into account issues of “fit” and leakage, while allowing the exhaled air to vent efficiently. Overall, we find that combinations of various commonly available fabrics used in cloth masks can potentially provide significant protection against the transmission of aerosol particles.

Make sure you’re wearing your mask properly and if possible layer some different kinds of fabrics to make it more effective. Your cloth mask should fit snugly but also be comfortable. It should be secured with ties or at least ear loops and you should be able to breathe while wearing it without it making you feel like you’re not getting enough oxygen. 

Make sure you’re also washing your masks and if you can make up enough for each day of the week so that you don’t end up wearing a dirty one more than once or something along those lines. When I have to go out for essentials during this pandemic, I make sure to wear my cloth masks.

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