Recently, there's been a lot of misinformation (and a lot of whining) about wearing masks during the pandemic.
For this demonstration, Dr. Davis held agar cultures near his face and sneezed, sang, talked, and coughed at them. For one set, he wore a standard surgical mask, and for the other he wore no mask.
He then left the cultures to grow the bacteria deposited by his respiratory droplets. So wherever you see a bacteria colony, that's an indication of where the droplets and bacteria from his mouth landed. It's crystal clear that the mask made a HUGE difference in the number of droplets that landed on the plates.
Dr. Davis told BuzzFeed that this demonstration isn't likely to show the difference between mask types, and in the thread he notes how this is definitely a demonstration, not an experiment. After all, it's a sample size of one, and COVID-19 is a virus, not a bacteria.
However, he expects that this demonstration would be "essentially the same" with other mask types (including N95, homemade, cotton, etc.), because essentially this shows that droplets leave our mouths when we cough, talk, sneeze, and sing, and that a mask can block most of them.
For example, the CDC has stated that COVID-19 spreads "mainly" through respiratory droplets like these, so we can infer that a mask would very likely block those droplets as well and with them, most of the viral load...even if this demonstration doesn't show that directly.
Of course, people also had some other questions for Dr. Davis, including wondering what he sang during the demonstration. Answer: some Hamilton!
