Are DIY Face Masks Efficient? If so which fabric to use?

Disclaimer: I am not a health professional nor an expert in the field and the findings below are a summary of papers I have read on the topic. 

You might be wondering if Do It Yourself (DIY) face masks are effective in protecting yourself from the current pandemic. There is a lot of conflicting information regarding the efficacy of DIY face masks but the overall evidence (see 1,2 below) shows that all types of masks reduce aerosol exposure (to a different degree though (see 3 below)) and hence bring a certain level of protection against viruses. In addition, you might be asymptomatic but still carry the virus. By wearing a mask, you slow the propagation / diffusion of the virus and protect others. The virus doesn’t spread on its own. People spread it. Finally, most of us touch our faces a dozen times every day. Wearing any type of masks will prevent you from touching your face and will decrease your chances of getting infected. 

 Here are some useful tips to create the most efficient DIY fabric masks:

1) Materials

A research by Cambridge University (see 4 below) shows that the most suitable household materials for a DIY face mask (in terms of ratio transmission / breathability) are: 

- cotton blend fabrics

- 100% cotton t-shirts (the stretchy quality provides a better fit and seal)

- pillowcases. 

The research shows that these materials filter cc 50% of of 0.2 micron particles (these are similar in size to the coronavirus). In addition, these materials are breathable (silk and linen can also be used but will be less effective). Moreover, the research shows that doubling the layers of materials for your DIY mask provides little incremental protection and decreases the breathability. 

2) Filter (see 5 below)

You can use wet tissues that have been dried (or any type of non-woven cloth such as toilet paper or gauze). 

3) Pattern / Methodology

Print the below pattern for a DIY fabric mask and adjust it to the size of your face / nose. The mask has two layers and allows you to insert a filter in between both layers. 

You will need two measures: 

A - B: Which is the distance between the top of your nose (between your eyes) and the tip of your nose (on the below pattern it is cc. 5cm)

B - C: Is the distance between the tip of your nose and your chin (on the below pattern it is cc 8.5cm). You will need to adjust the pattern to fit your face by adjusting the theses two lengths (see video below). 

 

Front panel face mask pattern
 A. Front Panel Pattern
DIY Fabric masks
 B. Front Panel Pattern (exact same size as front panel) 
.
Once you have adjusted the pattern to fit your face and cut out your your fabric you should end up with 2 pieces that look like a bat. Grab  two pieces of elastics (15cm each). If you don’t have any just use hair ties
Face Mask Pattern
1) Saw together A  - B and C - D (on each piece the front and the back piece)
You will end up with two pieces that look like this: 
DIY Face Mask Pattern
2) Cut through B - C on the back panel
DIY Face Mask Pattern
You will end up with a piece that looks like this:
DIY Face Mask Pattern
3) Double fold G - H and saw along B - C
You will end up with a back piece that looks like this: 
4) Put the pieces one on top of the other (or one inside the other) and the elastics in between both layers at the extremities: 
DIY face masks
5) Saw both pieces together all around the edges but get over the elastics as these should be able to slide.
 
Fabric face mask pattern
6) Saw the two extremities of the elastics together or make a double knot 
DIY Face Masks
7) Turn the mask inside out upside through the whole at the back
8) Iron the edges of the mask 
DIY Fabric Face mask
There you have it. Make sure to wear your mask correctly (the small edge at the top on the nose) and the bigger edge at the bottom
DIY fabric face Mask
If you decide to wear your own DYI mask make sure to: 
1) Wash your mask before wearing it the first time and after each use
2) Replace the internal filter (aka dried wet tissue or toilet paper) after every use
3) Prevent from touching the front of your mask with your hands while wearing it (put it on and remove it using the side elastics / stripes) 
4) Avoid wearing your DIY mask for more than 30 / 45 min. 
 
Here is a small video on how to adjust the pattern for your face / nose size: 
 
1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2662779/
2. http://www.myhealthbeijing.com/children/my-personal-fit-testing-heres-the-best-pollution-mask-for-me/
3. DIY face mask will not protect you as efficiently as professional (N95) masks because there are not 100% sealed around your airways (if someone sneezes directly into your face). Nonetheless, you should refrain from buying N95 or surgical masks (unless otherwise stated by your healthcare professional) as medical workers in your country are the ones that really them the most right now.
4.https://www.cambridge.org/core/services/aop-cambridge core/content/view/0921A05A69A9419C862FA2F35F819D55/S1935789313000438a.pdf/testing_the_efficacy_of_homemade_masks_would_they_protect_in_an_influenza_pandemic.pdf
5. https://www.facebook.com/permalink.php?story_fbid=2930468186974905&id=100000352576556