Fabric vs Standard Surgical Masks: Science in Plain English
Still confused about the whole mask situation?
Foreword
There is such a thing as good science and bad science. How can you tell the difference? It can be tricky to try and filter through all the bogus out there and find the truth (whatever that is, but we can save that argument for another day.) In this post, I have combed through a dry academic paper to bring you something more palatable. My hope for this post, and for the posts like it in the future, are that it is clear, true, and memorable. I want to equip non-science folks with information that I find so exciting, and I know that you will find it exciting, too! Just give it a minute to understand and you will be well on your way.
Publication of interest
“Assessment of Fabric Masks as Alternatives to Standard Surgical Masks in Terms of Particle Filtration Efficiency” by Amy Mueller and Loretta Fernandez.
A worthwhile endeavor
The researchers wanted to test different kinds of masks and see if they filtered particles in the air differently from each other. This study was important to conduct because the public are turning to home-made mask alternatives during the COVID-19 pandemic, but we do not know how effective these alternatives are at preventing the virus’ spread or protecting its wearer from being infected.
Testing the masks
There is a standard way for testing medical mask effectiveness, so the researchers adapted those steps to test 10 home-made and/or cloth alternatives to surgical masks that are being worn by the general public. The measured the percent particle removal of these masks and compared them to 3 commercially-produced surgical-type masks.
Why do we know how effective surgical masks are, but we don’t know how effective cloth/home-made masks are? Up until recently, it has not been relevant enough to require thorough research. It makes intuitive sense that covering your mouth and nose will prevent transmission or spread, but until recently, scientists had never bothered to investigate it in a detailed way.
There have surely been some studies that investigated this prior to 2020; however, science is only as strong as the number of scientists that have found the same results. Put simply, the more researchers that produce the same results, the more confident we can be that the research is accurate.
Sound scientific method
It is important that the scientists compared the home-made masks to the commercially produced ones because commercially-produced masks must be tested thoroughly. In other words, scientists know exactly how much a commercially-produced mask should be filtering according to what the manufacturer guarantees.
Confidence in their measurements
The authors of this publication were confident that their measurement method worked well since, as stated above, they got the results they expected from the commercially-manufactured masks that they tested. Therefore, they used the three commercially-produced masks as a “baseline” for what may be considered a generally acceptable amount of particle removal. More importantly, the researchers can know if their method of testing home-made face masks is working based on the results they get from the commercially-produced ones.
Incorporating previous research
The authors of this paper noted that previous research found home-made masks to be more effective if they were air-tight with a “nylon layer” over them to seal them, so they decided to test these results as well. It kind of looks like a stocking around half of someone’s head as you can see in the image below.
This way, they could either further confirm the findings, or dismiss them. Again, I want to reinforce that there is more power in science that can be confirmed repeatedly. If an experiment only produces a certain result once, what good is that? It does not give society anything helpful to work with.
Results
- The standard surgical mask effectively removed 75% of particles.
- 9 of the 10 home-made/cloth masks effectively removed 60% of particles (or less).
- Adding a nylon mesh (kind of like a stocking) over a mask improved its filtration effectiveness by 15–50%, and led to more consistent filtration over time.
- The home-made/cloth masks that achieved the best results (filtration efficacy comparable to commercially-made masks) were those that included a filter layer of organic cotton batting, Pellon, or loosely-woven cotton muslin, two layers of cotton fabric, and the nylon mesh over the top.
Conclusion
If you are looking to invest in a cloth mask, of if you want to make one at home, make sure your mask adheres to the guidelines. You want to invest in a few at a time since a mask should only be worn once, and then placed in a sealed bag until it can be washed. Having an extra mask or two when you are out and about may be the best way to go.
Lastly, a mask is only as effective as well as it is worn. You must follow the rules and instructions for wearing a mask. Otherwise, you run the risk of it being more of a fashion statement than a physical barrier of protection.
