Many of us are still very new to mask wearing and it can be confusing. It’s no surprise that this pandemic has left us overwhelmed as we work together to keep our communities safe. As governments across the globe recommend social distancing and wearing of face masks as our best defence against a global pandemic, how do we make the right choice? Let’s break it down to a few key points.
1) Find your perfect fit
A mask should fully cover your nose and mouth, extending an inch or more past the ends of your mouth and wrapping under to grab onto the bottom of your chin as an anchor. Masks with an aluminium nose bridge will generally have a much better fit. The mask should fit snugly but comfortably against the sides of your face and should not interfere with breathing. Research indicates that leakages around the sides of a mask can degrade filtering efficiencies by 60% or more. It’s important to keep in mind that finding a snug, yet comfortable fit, ensures that you are more likely to wear your mask for long periods of time and won’t need to constantly readjust.
2) Choose the right filtration system
Some fabrics can filter out more virus particles than others. There are two types of recommended yarns that go into fabrics for making masks: natural yarn such as cotton and synthetic yarns such as polyester or nylon. The main difference is that cotton will work as a mechanical filtration system, while a synthetic fabric such as polyester or nylon works as an electrostatic filtration system. Cotton is the more widely used material for masks, even dating back to the early 1900’s. This material performs better at higher thread counts which can make a significant difference in mechanical filtration efficiencies. That being said, a recent study showed that electrostatic filters, such as polyester or nylon, are generally most efficient at low velocities such as the velocity encountered by breathing through a face mask.
3) Protect with multiple layers
A general rule of thumb is that thicker, denser fabrics will do a better job than thinner, more loosely woven ones. The fabric performance depends on the type of yarn used, but also the density, yarn count and yarn mass. Multiple layers of fabric also means less chance that viral particles will be able to pass through. For the layer that will sit directly against your mouth, a comfortable, washable, tightly knitted fabric, such as polyester, nylon, or a spandex-cotton blend will be best. This kind of fabric wicks away the moisture from your breath, while allowing you to breathe. Materials made with 100% cotton tend to retain more moisture.
Covering the nose and mouth had been part of traditional sanitary practices against contagious diseases in early modern Europe. In 1897, the polish surgeon Johann Mikulicz, began wearing the first face mask after it was discovered that respiratory droplets carried culturable bacteria. Over the next few decades, masks quickly became widespread. In 1918 medical researchers published in the Journal of the American Medical Association “A mask may be repeatedly washed and used indefinitely.” In the 1960’s, with the rise of the single use culture, disposable masks became the convenient option over washing and sterilization. Today, with the innovation in high performance textiles and circular yarn, we can design for performance and sustainability that stands the test of time. The bottom line is this: any mask provides a better defence than no mask. But, by paying attention to the details, we put all the chances on our side so we can learn from the last century and make better choices for today's reality.
Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks: https://pubs.acs.org/doi/10.1021/acsnano.0c03252
Filtration Efficiencies of Nanoscale Aerosol by Cloth Mask Materials Used to Slow the Spread of SARS-CoV‑2: https://pubs.acs.org/doi/pdf/10.1021/acsnano.0c05025
A history of the medical mask and the rise of throwaway culture: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)31207-1/fulltext
Simple Respiratory Protection—Evaluation of the Filtration Performance of Cloth Masks and Common Fabric Materials Against 20–1000 nm Size Particles: https://academic.oup.com/annweh/article/54/7/789/202744