The little particles of mucus and saliva that people eject when they cough or sneeze could travel further than six feet – in theory at least, researchers reported Tuesday.
A computer model — not a real-life experiment — shows that a light breeze could carry some droplets as far as 18 feet.
It’s something to consider when setting up social distancing recommendations, said Dimitris Drikakis, an engineering professor at the University of Nicosia in Cyprus, and Talib Dbouk, his colleague.
“The work is based on modeling. We have not done experiments with people,” Drikakis told CNN.
Writing in the journal Physics of Fluids, Drikakis and Dbouk said their computer models suggested that current recommendations that people keep six feet apart might not provide safety under certain outdoor conditions.
“At a mild human cough in the air at 20 degrees C (68 degrees F) and 50% relative humidity, we found that human saliva-disease-carrier droplets may travel up to unexpected considerable distances depending on the wind speed,” Drikakis said in an email.
“When the wind speed was approximately zero, the saliva droplets do not go beyond two meters (six feet), which is within the social distancing recommendations. However, at wind speeds varying from (two to 10 mph), we found that saliva droplets can travel to distances up to six meters with decreasing concentrations and liquid droplets size in the wind direction,” he added.
“Our ﬁndings imply that depending on the environmental conditions, the two meters social distance may not be sufﬁcient.”
The coronavirus is carried in the small particles ejected when people cough, sneeze or talk. What’s not known is how much virus is carried in each particle, how much it takes to infect a person, and how well the virus survives in a particle that has traveled a longer distance and broken up as it goes.
“It is not yet known the amount of dosage required to affect a person,” Drikakis said. “The dosage would vary from one person to another. Further research and closer interaction between bio-medicine and engineering fluid physics are necessary to understand the conditions under which patients are being infected.”