A new study has found that cough droplets may travel as farther as 6 feet, potentially carrying enough coronavirus to infect a person.
Public health experts have been urging people to practice social distancing during the ongoing pandemic in order to curb the spread of the virus.
The study conducted by Singaporean researchers estimated how air droplets of various sizes might travel from one person coughing to another person standing either a meter or two away, or 3.2 feet and 6.5 feet away.
The researchers found that a person standing before a simulated cough at a distance of about 3 feet can get a direct hit of the virus, getting exposed to around 65% of all cough droplets. These droplets carry a tremendous viral load.
When the distance between a cougher and a bystander is 6.5 feet, some of the larger cough droplets reach the other person, delivering enough virus to infect the bystander.
However, larger cough droplets mostly fell down on the lower half of the body rather than the face, so the researchers think people do not inhale these larger droplets directly. However, the study authors think people may pick those larger droplets up on their skin or clothing, infecting themselves by picking that virus up while touching their faces.
Dr. Linsy Marr of Virginia Tech, who has been studying the aerosol transmission of the coronavirus, said, “Obviously, you don’t get sick from virus landing on your clothing. You would have to breathe it in or you would have to, you know, rub your hands all over your pants and pick up enough virus then touch your nose, eyes, or stick your finger in your mouth.”
“I don’t think that’s a big risk for transmission with this virus,” she added.
Dr. Marr explained that sneezes and coughs can be dangerous, but people have to be close, nearly face-to-face, to pass the virus.
“It has to be right in your face,” she said. “You have to be really close, and those droplets fly like mini cannonballs and would have to land in your eyes, in your nostrils, which point down, so it seems less likely, or on your lips.”
In general, viruses become airborne in two ways – heavier droplets that are expelled from the mouth or nose and smaller droplets that dry out quickly in the air.
Bigger droplets are known to have a copious amount of the virus, but they are heavy so they fall onto the floor or nearby surfaces after a person coughs.
On the other hand, smaller aerosols expel through the mouth or nose and dry out before they touch the ground. Smaller droplets continue to float in the air for minutes or even hours.
The researchers explained that shorter people, like children and teenagers, are at higher risk when a tall person coughs or sneezes. That’s because their faces are more in line with the stream of cough droplets.
The findings of the new study support earlier research from the Massachusetts Institute of Technology, which suggested that cough particles could travel as long as 6 feet.
Everyone should leave as much space as possible between themselves and others in order to curb the spread of the virus, according to the CDC guidelines. Dr. Marr said, “It’s a good guideline, but we shouldn’t think of 6 feet as a magic number. The farther the better.”
