Just wearing a face mask may not be enough to prevent the spread of COVID-19 without social distancing.
In a new project Physics of Fluids, by AIP Publishing, researchers tested how five different types of mask materials affected the spread of coronavirus droplets when we cough or sneeze.
Each material tested dramatically reduced the number of droplets dispersed. But at distances of less than six feet, enough droplets to potentially cause disease still reached different materials.
"A mask certainly helps, but if the people are very close to each other, there is still a chance of spreading or contracting the virus," said Krishna Kota, associate professor at New Mexico State University and one of the authors. of the article. "It's not just masks that help. It's both the masks and the distance."
At the university, researchers built a machine that uses an air generator to mimic people's coughs and sneezes. The generator was used to blow tiny liquid particles, such as the airborne droplets sneezing and coughing, through laser sheets into an airtight square tube with a camera.
They blocked the flow of the droplets in the tube with five different types of mask materials: a plain cloth mask, a two-layer cloth mask, a wet two-layer cloth mask, a surgical mask, and a medical-grade N-95 mask.
Each of the masks captured the vast majority of the droplets, ranging from the plain cloth mask, which lets about 3.6% of the droplets through, to the N-95 mask, which statistically retains 100% of the droplets. But at distances of less than six feet, even those tiny percentages of drops can be enough to make someone sick, especially if someone with COVID-19 sneezes or coughs multiple times.
A single sneeze can contain up to 200 million tiny virus particles, depending on how sick the carrier is. Even if a mask blocks a huge percentage of those particles, enough can escape to make someone sick if that person is close to the wearer.
"Without a face mask, it is almost certain that many strange droplets will be transferred to the sensitive person," said Kota. “Wearing a mask provides substantial, but not complete protection to a susceptible person by reducing the number of strange sneezing and coughing droplets in the air that would otherwise enter the person without the mask. Attention should be paid to minimizing or avoiding direct face-to-face or frontal human interactions, if possible. "
The study also did not take into account leakage from masks, whether worn correctly or improperly, which may contribute to the number of droplets released into the air.
The article, "Can face masks protect against sneezing and airborne cough drops in close-up, face-to-face human interactions? A quantitative study,Is written by Krishna Kota, Javed Akhtar, Abner Luna Garcia, Leonardo Saenz, Sarada Kuravi and Fangjun Shu. The article was published in Physics of Fluids on December 22, 2020
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