He tested sneezing, talking, singing, and coughing with a mask and without one.
Recently, there’s been a lot of misinformation (and a lot of whining) about wearing masks during the pandemic.
In response, scientists and medical professionals have been trying their damnedest to stop the spread of disinformation on platforms like Facebook and Twitter.
Microbiologist Rich Davis is one of those. In a viral (no pun intended) tweet, he showed the results of a demonstration he put together showing just how big of a difference masks can make in halting the spread of respiratory droplets.
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 also demonstrated the effectiveness of distance on the spread of droplets, standing at two feet, four feet, and six feet away from the culture plates and coughing hard for 15 seconds with and without a mask. While a six-foot difference greatly reduced the presence of bacteria, the mask still appeared more effective in all cases.
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.
Dr. Davis also addressed in the thread that there are certain data points that we can infer from the demonstration, although it doesn’t explicitly show 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.
So while this isn’t a robust experiment about the different types of masks and how effective they are against COVID-19 specifically, we can get a lot of visual data about just how well masks can reduce transmission of droplets in general. Even a homemade cloth mask is going to be better than nothing!
Of course, people also had some other questions for Dr. Davis, including wondering what he sang during the demonstration. Answer: some Hamilton!
In short, Dr. Davis recommends that face masks and face shields should be a normalized part of hygiene, just like washing our hands or sneezing into tissues. So put ’em on, folks!
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