Early on in the COVID-19 pandemic, the Center for Disease Control and Prevention (CDC) defined exposure to coronavirus as being closer than six feet to an infected person for 15 minutes or more. However, new research shows that this definition may not be as accurate as once thought.
John Brooks, MD, Chief Medical Officer of the CDC’s COVID-19 response, recently announced that these guidelines should really be viewed more as a rule of thumb, rather than a full-proof way of protecting oneself from the virus.
In fact, Brooks noted that short interactions with an infected person could be just as dangerous as those surpassing the 15-minute mark.
“Context really matters here,” he said. “It might be short, but if your voice was raised, say to speak over loud machinery, or if someone was coughing or sneezing, you might want to err on the side of caution.”
In fact, research conducted by Lydia Bourouiba, a fluid dynamics scientist at MIT, showed that a sneeze can travel up to 27 feet. And, even after the larger aerosol droplets fall to the ground, smaller particles can remain suspended in the air for up to 14 minutes after someone sneezes or coughs or a conversation has ended.
“That has implications for how many people you can put in a space,” Bourouiba said. “It has implications for how to handle teamwork and meetings, especially if the airflow isn’t changed regularly.”
Another paper published in Physics of Fluids revealed that a sneeze or cough can transfer to objects and individuals up to 13 feet away, even without wind. With a slight breeze, the distance particles can travel increases to 18 feet in five seconds. So really, the further you can distance yourself from others, the better.
“This work is vital, because it concerns health and safety distance guidelines, advances the understanding of spreading and transmission of airborne diseases, and helps form precautionary measures based on scientific results,” Dimitris Drikakis, study researcher, said in a press release.
However, there are still some unknowns to consider.
Dr. Amesh Adalja, an infectious disease expert, said it is important to note that while this research suggests saliva may be able to travel much farther than six feet, it does not give proof that coronavirus is able to survive long enough to infect a person from that far away.
“There are still a lot of questions out there,” he said.
Jagdish Khubchandani, Ph.D., an associate professor of health science at Ball State University in Indiana, said that regardless, this is why wearing a mask is an absolute must. With so many unknowns, the one thing that has proven to be true is wearing a mask that prevents respiratory droplets from traveling through the air and helps slow the spread of COVID-19.
“We have generated enough evidence over the past few months to suggest that one of the best protective mechanisms are masks, and, maybe, it should become a part of life like watches, scarves, and other accessories,” he said.