Dr Richard Davis conducted an experiment which demonstrated that a face mask blocked “virtually all” of respiratory droplets coming from his mouth and throat when he coughed and sneezed.
He said: “First, I sneezed, sang, talked & coughed at an agar culture plate with or without a mask.
“Bacteria colonies show where droplets landed. A mask blocks virtually all of them.”
The pictures show a significant difference between the culture plates. Hardly any bacteria colonies landed on the culture plate that the doctor sneezed at when he was wearing a face mask.
For his next experiment, Dr Davis looked at how effective face masks could be when it comes to social distancing.
He set up open bacteria culture plates at distances of two, four and six feet and coughed “hard” for 15 seconds.
“As seen by number of bacteria colonies, droplets mostly landed <6 ft, but a mask blocked nearly all of them,” said Dr Davis.
He added: “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”.
In the UK, it is mandatory to wear a face mask on public transport while in the US the Centres for Disease Control (CDC) and Prevention has recommended that people wear face masks or coverings in public places.
“Cloth face coverings are most likely to reduce the spread of Covid-19 when they are widely used by people in public settings,” says the CDC on its website.
Dr Davis called for the depoliticisation of the act of wearing face masks on Twitter.
He wrote on Twitter: “Masks as a political/social litmus test or used to shame those who won’t (or disabled folks who truly can’t!) wear them is a travesty.
“We wash hands after using the bathroom & wipe noses on tissues.
“Masks/face shields need to be just another normalized act of hygiene.”