The CDC has given US doctors the green light to start advising the public to wear masks…in public. This is good! While social distancing, eye protection, and GOOD hand-washing remain critical to our ongoing survival, even a simple cloth can catch some spit on the way out of the mouth and slow the spread person-to-person. So why not wear one?
The question then becomes which one to wear! In previous posts I’ve featured a design from MIT engineers using NWPP from reusable shopping bags. This is material is tightly woven and should work well to intercept a fair number of virus particles. However, what if you don’t have access to that material? Or as much of it as you want? When should you use in you masks then?
The answer, for now at least, is at least two layers of fabric: A tight-woven cotton on the outside and a flannel on the inside!
This current solution, which offers protection not only from spreading viral particles but also from breathing them in, arises from combining the CDC’s simple facemask design with research out of Wake Forest University. The chair of the department of anesthesiology there, Dr. Segal, is reported to be recommending heavyweight “quilters cotton” with a thread count of at least 180 on the outside and flannel on the inside. I’m working on getting my hands on the original research, but this design claims to cut transmission down to 60-80%. If true, that’s about as good as standard surgical face mask!
Quilting has gone HARDCORE
The white squares are an example of thick quilting fabric. Patterned or non- patterned is fine!*
What should you do if you ONLY have pillow cases or t-shirts to spare and don’t know their thread-counts? Following the rule of “thicker is better,” keep adding laters!
If you have pillowcases or t-shirts of unknown thread count, fold them into four layers or more layers. More layers means more density in the mask and more threads the virus has to pass through: more chances for it to get caught on one of them and pass no further.
It will be tougher to breathe through-that’s the point! Hang in there and please don’t forget to wash these daily! Abundant soap and water or machine water, then hang to dry. (No bleach, no chemicals toxic to people. You will be wearing these next to your face!) And if you only have one-layer masks, that’s ok! Wear them both, wash them both, and press on. Remember which one is on the inside so that you can wash that one more throughly and more often, if you choose, that then world-facing, outside mask.
I know that this all sounds scary: tiny viruses and masks and illness everywhere. You’re right! I feel that way, too. Through it all, remember: you are necessary. You are important. Whether you are serving on the front lines of medicine, providing a vital service, or just staying home and helping flatten the curve, you are playing a role in the fate of the world. WHAT YOU DO NOW MATTERS. It has always mattered, but your impact on others is more tangible now than ever! So thank you for staying safe, staying home when you can, and when you can’t, masking up like a hero!**
*If not using two different fabrics that are easily distinguishable from each other, use two different colors so that you know which is inside and which is outside. That will improve safety for you if you need to take off the mask and put it back on again before washing it!
**Wearing simple, one-layer cotton masks has been shown in limited studies of people NOT in hospital populations to decrease virus transmission. The most important factor in those tests, apart from fabric density, was likely a good fit to the face.