A scientist with the National Institute of Standards and Technology (NIST) created a video that shows the differences in airflow when a person wears a face mask and when they do not, demonstrating how much air is expelled from a person’s nose and mouth in each instance. The video aims to demonstrate how wearing a face covering can help slow the spread of infectious diseases such as the novel coronavirus.
Matt Staymates, a fluid dynamicist and mechanical engineer at the NIST, typically uses advanced fluid flow visualization tools when helping to detect “drugs and explosives through the flow of fluids that are usually invisible,” he wrote in a blog post.
“When I’m in the laboratory, I use a number of advanced fluid flow visualization tools to help better understand and improve our ability to detect illicit drugs and explosives on surfaces, on people, and in the environment,” he explained.
But given the ongoing coronavirus pandemic, he decided to use the same tools to conduct an at-home lab to show the differences in airflow when a person is wearing a face mask and when they are not, hoping to help others understand how covering their face while in public can protect others and may even offer some self-protection, too.
Over a series of weeks, the scientist compiled more than 50 gigabytes of video data that showed him coughing over and over, first showing the effects on airflow when no face covering was used, and then subsequently showing the impact on airflow when using coverings such as a bandanna or homemade mask.
By the end, “We learned that even the simplest face coverings (bandanas, ski neck warmers, etc.) stopped much of your cough from landing on someone else,” wrote Staymates in the blog. “We also learned that a good seal around the nose, chin, and cheeks helps to prevent your cough from 'leaking' out of the covering. And pulling your face covering below your nose is not good — you would be surprised how much air comes out of your nose when you cough."
“Additionally,” he continued, “we found that fabrics with very tight and nonporous weaves actually increase air leaking out by the nose and chin. So, while these tight fabrics may filter droplets at greater efficiency, they are not breathable and could possibly defeat the purpose of the face covering. Another interesting observation was the impressive reduction in airflow velocity while talking with all the face coverings — a good thing considering that most people out in public should be talking far more than coughing.”
It's important to note that the video Staymates created only shows airflow while coughing, not the movement of virus particles.
Top health agencies such as the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) both recommend the use of face masks or coverings while in public, and recent studies have concluded face mask usage can help prevent a COVID-19 infection.
However, other precautions — namely frequent hand washing and keeping at least 6 feet away from others while in public, when possible — should also be adhered to, experts have warned.