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Simply wearing a mask may not be enough to prevent the spread of COVID-19 without social distancing, the findings of a new study suggest.
In AIP Publishing’s Physics of Fluids, researchers tested how five different types of mask materials impacted the spread of droplets that carry coronavirus when we coughed or sneezed.
Each material tested drastically reduced the number of droplets that spread. But at distances of less than 6 feet, enough droplets to potentially cause disease passed through several of the materials.
“A mask definitely helps, but if people are very close to each other, there is still the possibility of spreading or contracting the virus,” said Krishna Kota, an associate professor at New Mexico State University and one of the authors of the paper. “It’s not just the mask that helps. It’s both the masks and the distancing.”
At the university, researchers built a machine that uses an air generator to mimic human coughs and sneezes. The generator was used to blow small liquid particles, such as airborne droplets from sneezes and coughs, through laser sheets into an airtight square tube with a chamber.
They blocked the flow of the droplets into the tube with five different types of mask materials: a regular cloth mask, a two-layer cloth mask, a two-layer wet cloth mask, a surgical mask, and an N-95 of medical grade mask.
Each of the masks captured the vast majority of the drops, from the regular cloth mask, which allowed about 3.6% of the drops to pass through, to the N-95 mask, which statistically stopped 100% of the drops . But at distances of less than 6 feet, even those small percentage drops can be enough to make someone sick, especially if a person with COVID-19 sneezes or coughs multiple times.
A single sneeze can carry up to 200 million tiny virus particles, depending on how sick the carrier is. Even if a mask blocks a large percentage of those particles, it could escape enough to make someone sick if that person is near the wearer.
“Without a mask, a lot of strange droplets will almost certainly transfer to the susceptible person,” Kota said. “Wearing a mask will offer substantial, but not complete, protection to a susceptible person by decreasing the amount of sneezing and foreign cough droplets in the air that would otherwise enter the person without the mask. Consideration should be given to minimizing or avoid being around – facial or frontal human interactions, if possible. “
The study also did not take into account leakage from the masks, whether they are used properly or improperly, which can increase the number of droplets reaching the air.
