Blocks respiratory droplets coming from your mouth and throat. The document summarizes two demonstrations of how masks block respiratory droplets. In the first demo, sneezing, singing, and coughing toward agar plates with and without a mask showed that a mask blocks virtually all droplets, as seen by bacteria growth. The second demo placed plates at distances of 2, 4, and 6 feet when coughing with and without a mask, showing droplets only reached the furthest plate without a mask. Both demonstrations indicate masks nearly completely block transmission of droplets.

1. What does a mask do?
Blocks respiratory droplets coming
from your mouth and throat.
By Austin Williams
Prepared By
Yousef Elshrek

2. • Two simple demos: First, in case of sneezing, singing, and coughing toward an agar culture plate with or
without a mask. Bacteria colonies show where droplets landed.
• A mask blocks virtually all of them.
Byhttps://images.foxtv.com/static.foxla.com/www.foxla.com/c
ontent/uploads/2020/06/932/524/demo-1.jpg?ve=1&tl=1 Austin
Williams
• In this demonstration presence of bacteria (not viruses)
on plates is only meant to be proxy for microbes present
in respiratory droplets.
• Likely smaller aerosolized droplets (that could carry
viruses like SARS-CoV-2) are also produced by
sneezing, singing, talking and coughing and that those
would travel further and stay in the air longer than larger
respiratory droplets.
• The images of the experiment showed that every action performed unmasked nearly covered each
Petri dish in bacteria, while the dishes used during the masked demonstration were left nearly
untouched.
• Sneezing and coughing left the most noticeable difference on the plates.

3. Byhttps://images.foxtv.com/static.foxla.com/www.foxla.com/content/uploads/2020/06/932/524/demo
-1.jpg?ve=1&tl=1 Austin Williams
• In the second demonstration, showed how keeping one’s distance makes a difference in
stopping the spread of respiratory droplets.
• setting open bacteria culture plates 2, 4 and 6 feet away and coughing (hard) for ~15s, with
repeating this without a mask.
• The pictures show that standing two feet apart with no mask practically covered the Petri
dish with bacteria. Davis’ respiratory droplets also managed to land on the dish at four feet
with no mask with scarce amounts still managing to get on the dish from six feet away.

4. • But no matter the distance, the demonstration showed that a mask nearly
completely blocked bacteria from landing on the plates.
• Researher also noted that besides the actions shows in his demonstration, the
simple act of breathing is also a source of spreading respiratory droplets.
• “Just breathing (exhaling) does release moisture from your lungs – think of
when you breathe out onto a pane of glass
• Also, during the act of normal breathing, you might clear your throat, laugh,
or sigh.
• Would there be as many droplets, and potential microbes, spread as by
coughing and sneezing (common symptoms of respiratory tract infections)?
Probably not, but it is possible there could be some.”
• This experiment “was primarily looking at the way a mask can block
droplets and secretions from your mouth.”

5. • Colonies of normal bacteria from my mouth/throat show the spread of large
respiratory droplets, like the kind we think mostly spread #COVID19, and
how a mask can block them.
• The U.S. Centers for Disease Control and Prevention recommends wearing
a cloth face covering while in public to help combat the spread of COVID-
19, especially in settings where social distancing measures can be difficult
to maintain.
• Research shows that the material of your mask matters, and by using a
surgical-grade face covering in this demonstration, any type of material, a
hospital grade surgical mask, a homemade cotton mask, even a tissue paper
held in front of my mouth, would likely have had the same effect in what
these bacteria culture plates looked like.”
• Reference

6. Reference
• Doctor demonstrates how face mask blocks respiratory ...fox6now.com › 2020/06/30
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