Researchers have proved the effectiveness of masks with human models, and conducted similar experiments at different distances. It is found that the combination of mask and social distance can significantly reduce the risk of COVID-19 infection when a person comes into contact with an infected person.
Many scientists have conducted simple experiments and studies to prove how masks block tiny particles like SARS-CoV-2, and prove that masks will not pose any safety threat to the wearer. The latest such research concluded that masks play a "key" role in preventing the spread of COVID-19.
Researchers have conducted a series of experiments involving human models to simulate particle transmission with and without masks. As you can see in the following clip, the researchers want to measure the effectiveness of masks in blocking aerosols and droplets. They use mannequins to simulate how infected people spread droplets when wearing any kind of masks (from medical masks to cloth masks). They also studied how mannequins spread the same particle flow without wearing a protective mask.
The researchers also studied the requirements of social distance, and found that the farther the distance between people, the lower the risk of infection, especially in combination with the use of masks.
"We found that the most important measure to reduce the exposure risk of COVID-19 is to wear a mask," said Dr Matthew Callstrom. "We found that disposable paper medical masks and double-layer cloth masks can effectively reduce the spread of droplets, and we did not find any difference in blocking aerosol particles emitted by wearers among mask types."
"The most common transmission mechanism of COVID-19 is through respiratory droplets, which are larger than aerosols and are easier to block with masks." The doctor added.
Both CDC and WHO believe that the virus is mainly transmitted by droplets, and both institutions acknowledge the risks of aerosol transmission. The researchers released the following picture, which compares the size of SARS-CoV-2 virus with that of 2 micron particles, in order to represent the size of aerosol particles that may contain SARS-CoV-2.
The study also measured the different distances of aerosol particles from the source to the target. The researchers found that the number of particles decreased with the increase of distance, and supported the guidance of CDC on keeping social distance, suggesting that the distance between people should be 6 feet. The following figure shows the exposure risks based on masks and social distance. The researchers found that even if the distance between two subjects was more than six feet, the mask would help.
"I think we have a certain understanding of the importance of masks. Some studies have shown that masks can effectively block viruses, but what really matters here is how effective masks are when both sides make masks," said Dr Elle Berbari.
"We objectively found that masks are very important to protect ourselves and people around us," Callstrom said. "If you wear a mask, you are protecting others. If they wear masks, they are protecting you. "