Toronto 
With the CDC and Canadian Public Health officials recommending non-medical masks to protect others around you when you are in places where it is difficult to ensure proper physical distancing, many people are making masks with various kinds of materials.
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Smart Air Filters has done a comprehensive study on the materials used from coffee filters and bed sheets (including thread count), to reusable non-woven polypropylene shopping bags, and blue shop towels.
HOW WAS THE TESTING DONE TO DETERMINE THE BEST MATERIALS
Smart Air Filters tested over 30 materials for their ability to filter large-sized and small-sized particles using what is called a Henderson apparatus. For example, Ebola virus is about 1 micron in size, the size of the smallpox is about 0.3 micron, while COVID-19 particles measure 0.06-0.14 microns in size, but 1-10 microns when in droplets (aerosolized) – droplets of saliva discharged by people sneezing or coughing, and particles that remain in the air are generally 1 to 5 mm.
The materials were also tested for the breathability factor or how easy it is to breathe through the materials.
They illustrated a fabric test that can be done at home by holding your material up to the light, checking how much light passes through it and comparing it to the chart (shown below) to estimate the effectiveness of your material.
WHAT IS THE BEST MATERIAL FOR MAKING HOMEMADE MASKS
Findings:
- The HERO coffee filter (difficult to breath through), 40D nylon (difficult to breath through), CHEMEX coffee filter, the dish towel, and canvas (difficult to breath through) captured more than 45% of 0.3 micron particles.
- Natural fibers (like cotton and paper) generally filtered better than synthetic fibers (like polyester and polypropylene).
- Materials like coffee filters perform very well at filtering tiny particles, but they are difficult to breathe through.
- Interesting Finding: The bra pad performed quite well, filtering 14% of 0.3-micron particles, and 76% of 1.0 microns.
Recommended Materials based on breathability and filtration effectiveness (according to Smart Air Filters):
- Denim (10oz) – (The higher the ounces, the heavier the denim. Jeans under 12 oz. are considered Lightweight, 12 to 15 oz. jeans are Mid-weight, and anything 16 oz. and above is a Heavyweight)
- Bed sheets (80-120 thread)
- Paper towel
- Canvas (0.4-0.5mm thick)
- Shop towels
Please remember that these masks will NOT completely protect you from COVID-19. Please follow Health Canada recommendations.
