Researchers Visualize the Cough Airflows Under Various Masks
We hear it all the time. Wear a mask to protect yourself and others from COVID-19. But many still don't believe that masks are effective with some even claiming that masks increase COVID-19 risk.
Now a new study is seeking to prove that they are indeed effective. "If a person can reduce the extent of how much they contaminate the environment by mitigating the spread, it's a far better situation for other healthy individuals who may enter places that have such contaminated areas," said Padmanabha Prasanna Simha, from the Indian Space Research Organisation.
All well said but how do Simha and his team plan on proving the effectiveness of masks? The researchers experimentally visualized the flow fields of coughs for various common masks.
Since coughs tend to be warmer than their environment, Simha and his team utilized a technique called schlieren imaging, a visual process that is used to photograph the flow of fluids of varying density, to capture images of coughs. They experimented with this technique on five test subjects.
They proceeded to track the motion of a cough over successive pictures. As such, they were able to estimate the cough's velocity and the spread of its expelled droplets.
The end result of their study revealed that N95 masks were the most effective at reducing the horizontal spread of a cough. The N95 masks limited a cough's spread to between 0.33 and 0.82 feet (0.1 and 0.25 meters), compared to up to 10 feet (3 meters) for an uncovered cough.
But it wasn't just N95 masks that were effective. Even a simple disposable mask could limit a cough's spread up to 1.64 feet (0.5 meters).
"Even if a mask does not filter out all the particles, if we can prevent clouds of such particles from traveling very far, it's better than not doing anything," said Simha. "In situations where sophisticated masks are not available, any mask is better than no mask at all for the general public in slowing the spread of infection."
Simha and his team also found that covering a cough with an arm was simply not effective as the particles flew in all directions. There you have it! Masks work and they work well so keep on wearing them!