Research has shown that simply wearing a mask without social distancing cannot prevent the spread of COVID-19.
Researchers tested fluid physics to see how the five types of mask materials affect the spread of coronavirus-carrying droplets when coughing or sneezing.
All of the tested materials dramatically reduced the number of spreading droplets. However, at a distance of less than 6 feet (1.82 meters), enough droplets have passed through several materials, potentially causing disease.
“Masks are definitely helpful, but if people are very close to each other, there is still a chance that the virus will spread or become infected,” said Krishna Kota, associate professor at New Mexico State University and one of the authors of the study. have. It’s not just the mask that helps. Both the mask and the street.”
At the university, researchers used air generators to build machines that mimic human coughing and sneezing. The generator was used to blow small liquid particles, such as sneeze and cough drops, floating in the air through a laser sheet in a closed square tube with a camera.
They used five types of mask materials (plain cloth mask, double cloth mask, wet double cloth mask, surgical mask, and medical N-95) to block the flow of water droplets in the tube.
Each mask captured most of the water droplets, from a regular cloth mask that allows about 3.6% of the water droplets to pass through, to the N-95 mask that statistically blocks 100% of the water droplets. However, at a distance of less than 6 feet, even a small amount of water droplets can cause infection. This is especially true if a person with COVID-19 sneezes or coughs several times.
One sneeze can carry up to 200 million tiny virus particles, depending on how sick the carrier is. Even if the mask blocks a huge percentage of such particles, if the person is close to the carrier, the droplet can escape enough to infect someone.
“Without a face mask, it’s almost certain that a lot of foreign matter will pass to the vulnerable,” Kota said. Wearing a mask provides practical protection for a vulnerable person by reducing the number of sneezing and coughing droplets in the outside air that can invade a person without a mask, but it is not complete. “If possible, be careful with face-to-face interactions so that you don’t put your face close together.”
This study also did not account for leakage of the mask, whether worn properly or improperly. This can increase the number of droplets entering the air.
The study was published online in the journal Physics of Fluids on the 22nd (local time).
* “Can face masks offer protection from airborne sneeze and cough droplets in close-up, face-to-face human interactions? A quantitative study,” Physics of Fluids, aip.scitation.org/doi/10.1063/5.0035072
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