By Louisa Moller

BOSTON (CBS) – As restaurants around the country slowly open their doors, researchers say it takes more than staying six feet apart to stay safe from coronavirus.

“Just sharing an enclosed space with lots of people and spending time in there, so an hour for a lunch or an hour and a half for a dinner, seven hours in a call center, leads to massive spread,” said Dr. Erin Bromage, a biologist at the UMass Dartmouth.

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Bromage wrote a blog post about the impact of airflow on the spread of coronavirus that has been shared roughly 11 million times. He hypothesizes that viral particles can spread farther than six feet in airstreams.

A recent study out of China showed that one restaurant customer with COVID-19 spread the disease to four others at their table but the infection did not stop there. It was spread to both tables on either side of the diner’s table.

“The table beside them that had just a gentle air conditioning breeze blowing from one side to the other, three quarters of that table, so three out of four of those people also became sick,” Bromage said.

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Graphic shows how coronavirus spreads through air (Image credit University of Oregon)

Bromage says the more time spent in an enclosed environment like a restaurant or group office, the greater the chance of infection. “You have to get exposed to enough virus in order to establish an infection,” he said.

Researchers from the University of Oregon created a 3D model of viral particles spread in an enclosed space. They also showed that when a window is open in that space, fewer people are sickened.

Bromage says the fresh air is where he would feel most comfortable dining. “I would have little hesitation when we are given permission to do this to go and eat in an outdoor restaurant or an area that had that,” he said.

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He also argues that restaurants should eliminate music, allowing diners to speak in softer voices and thus, emit fewer viral particles.

Louisa Moller