What does a mask do?

What does a mask do?

Blocks respiratory droplets coming from your mouth and throat.

Two simple demos: First, I sneezed, sang, talked & coughed toward an agar culture plate with or without a mask. Bacteria colonies show where droplets landed. A mask blocks virtually all of them.

What about keeping your distance?

Second demo: I set open bacteria culture plates 2, 4 and 6 feet away and coughed (hard) for ~15s. I repeated this without a mask. As seen by number of bacteria colonies, droplets mostly landed <6 ft, but a mask blocked nearly all of them.

I’m aware that this simple (n=1) demo isn’t how you culture viruses or model spread of SARS-CoV-2. But 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!

My mask vs. no mask demonstrations got perfectly summarized in this brief 34 second video. Masks keep your respiratory secretions to yourself!

Something extra cool, local reporter Kevin Kim came to our teaching lab and tried this same demonstration himself (his reaction in this clip was absolutely genuine). Story airs tonight
The take home: masks matter!

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