May 2, 2020 at 12:29 AM EDT – Updated May 2 at 4:37 PM
(CNN) – As some states start to reopen, the coronavirus is still spreading and officials still recommend people stand six feet apart, but is that really how far germs can travel from a cough?
At a lab at Florida Atlantic University, two engineering professors are measuring the power of a cough. Using a dummy, they filled its mouth with a mix of glycerin and water and then with a pump, forced the dummy to cough to see how far the droplets travel.
“It generates particles on the order of 10 to 20 microns, which is roughly close to what the smallest droplet sizes are when we cough,” Sid Verma, Assistant Professor of Engineering at Florida Atlantic University, said.
The droplets traveled a distance of three feet almost immediately. Within five seconds, the droplets were at six feet and then nine feet in just about 10 seconds.
Nine feet is beyond the recommended social distancing guidelines.
The fog of droplets lingered in the air, but kept moving forward, taking another 30 to 40 seconds to float another three feet.
Over and over again, the simulated droplets blew past the six foot mark, often doubling in distance.
“At nine feet, they could linger for, provided it’s still air, two to three minutes, but the concentration is less than what it would be at six feet…” Manhar Dhanak, Chairman of the Engineering Department at Florida Atlantic University, said.
The professors say the droplets become less dense the further they travel, but they still hang in the air, still with the ability to carry disease.
They even put a mask on the dummy and the particles still dispersed from the sides of the mask, but they did not travel very far. Droplets from a cough can linger in the air for as long as three minutes.
“Six feet is the minimum distance that you should keep. It seems that…further is better,” Dhanak said.
The Centers for Disease Control and Prevention recommends standing six feet away from other people and wearing cloth face coverings when social distancing is difficult, like at grocery stores and pharmacies.
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