The benefits of face masks have been highly debated amid the coronavirus pandemic and now a new study has swayed in favour of wearing masks in public.
Researchers from Florida Atlantic University have demonstrated just how far droplets can travel from a cough, both with and without a face mask.
In the study, the team used a machine to emulate a cough from the mouth of a mannequin.
Dr Manhar Dhanak, who led the study, said: “Our goal was to demonstrate the fate of smaller size particles that are present in the exhaled jet of a cough.
“We used a mixture of distilled water and glycerin to represent the synthetic fog that made up the content of the cough-jet that was expelled from the mannequin’s nose and mouth during our experiment.
“The fog is initially warmer than the ambient air, just as in the case of an exhaled cough-jet, however, it cools as it travels through the air.”
To make the particles really stand out, the researchers used LED and laser lights.
Dr Siddhartha Verma, a researcher on the project, explained: “Preliminary results from our experiment reveal that significant concentrations of small particles from a turbulent jet such as from a heavy cough/sneeze can linger in still air for more than one minute.
“It only took the particles a couple of seconds to travel 3 feet; in about 12 seconds it reached 6 feet and in about 41 seconds it reached around 9 feet.”
Worryingly, for a heavy cough, the researchers found that particles could travel up to 12 feet.
However, the team found that wearing a face mask can slow down these cough jets.
Dr Dhanak added: “In the case of light coughing, it can lead to formation of vortex rings in which the particles and droplets ejected in the cough-jet remain confined to evolving toroidal flow structures.
“The rings appear to travel 1 to 9 feet or more before getting diffused and breaking up. We found that wearing a face mask doesn’t stop the particles 100 percent, but it does slow down the cough jets.”
Based on the findings, the researchers suggest that it may be beneficial for the public to wear face masks while out and about.
Dr Stella Batalama, who oversaw the project, added: “There is currently a gap in knowledge over how COVID-19 spreads as well as a scientific debate about how the disease moves in the air.
“This experiment will help to shed more light on the spread of the disease through aerosols. Moreover, it underscores why it is so essential to cover your cough and sneezes and to wear a face mask when you are out in public settings.”
