Coughs Can Send COVID Virus Farther Than 6 Feet
November 5, 2020 – Droplets from a cough can travel over 6 feet and could potentially carry enough COVID-19 virus to infect another person, according to a new study.
Public health officials have urged everyone to practice social distancing during the COVID-19 pandemic, which means leaving space between you and the people you don’t live with. This new study adds to other research that reveals that these guidelines – the CDC advises keeping at least 6 feet between you and other people – may not go far enough.
In the latest study, researchers from Singapore estimated how droplets of different sizes could pass from a coughing person to one standing 1 meter or 2 meters away, or 3.2 feet and 6.5 feet, respectively.
The study found that at a distance of about 3 feet, a person standing in front of a simulated cough actually receives a direct attack of the virus, covering themselves with about 65% of all droplets generated by that cough. Most of the droplets that reach the viewer are of the oily and wet type that are heavy and fall to the ground and nearby surfaces after a sneeze or cough. The study’s authors write that these droplets carry a “huge” viral load.
When the cougher and bystander are 2 meters, or 6.5 feet apart, fewer larger droplets reach the other person, but a cough still delivers just enough virus to potentially infect the other person.
But in both cases, the droplets were coming down from the nose and mouth of the coughing person, so most of them fell on the viewer’s lower body. Because of this, researchers believe that people probably don’t inhale these large droplets directly, but can pick them up on their skin or clothes, and then become infected when they catch this virus on their hands and touch their face.
“Obviously, you don’t get sick from a virus landing on your clothes. You would have to breathe it in or you would have to, you know, rub your hands all over your pants and catch enough virus, then touch your nose, your eyes or put your finger in your mouth, ”says Linsey Marr, PhD, a civil engineer. and environmental at Virginia Tech, which studies aerosol transmission of the virus. “I don’t think it’s a great risk of transmission with this virus.”
Sneezing and coughing can be dangerous, she says, but two people would have to be very close to each other, almost face to face, to transmit the virus that way.
“It must be fair in your face. You have to be very close, and those droplets fly like mini cannonballs and should land in your eyes, in your nostrils, which are pointing downwards, so it seems less likely, or on your lips, ”says Marr.
Viruses can spread through the air in two ways: as large, heavier droplets that are expelled from the nose or mouth, and through aerosols, droplets so small that they quickly dry out in the air. The larger droplets contain more copies of the virus, but they are also heavy and fall quickly to the ground and nearby surfaces after a sneeze or cough. Smaller aerosols, which can be generated at the back of the throat when we speak, talk or even sing, dry out before they reach the ground, and which allows them to continue to float in the air for minutes or even hours, and may still be present after a person leaves a room.
Researchers say smaller people, like young children and teens, may be at greater risk when a larger adult coughs because their faces are more aligned with the flow of these droplets. They say during the pandemic, smaller people may want to stay more than 6 feet from taller people for this reason.
The new findings support earlier work by researchers at the Massachusetts Institute of Technology, who suggested that particles from a cough, carried by the hot air in our breath, could travel much further than 6 feet in a cloud of turbulent gas.
And because the smaller aerosols – which are generated just by talking or singing – can travel longer distances, everyone should leave as much space as possible between themselves and the others.
Guidelines like the CDC are the best guesses, and researchers have tried to figure out exactly how the virus travels from person to person in the air.
“It’s a good guideline, but we shouldn’t think of 6 feet as a magic number. The farther the better, ”says Marr.
As researchers continue to unravel the mysteries of how people get COVID-19, public health experts say it’s important to take a layered approach to safety. No single strategy can protect you entirely on its own. That’s why it’s important to take all of the recommended precautions to protect yourself from the virus, including washing and disinfecting your hands, wearing a face mask, limiting travel and social interaction, and keeping a space between you. And the others.
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