The Best Evidence Yet Why 6 Foot Distancing Will Not Work
New research shows that the 6-foot distancing rule may not be a sufficient barrier in an interior space without good ventilation.
Effectiveness of Six Foot Social Distancing Questioned
The message for months now has been to maintain 6-foot distancing to avoid infection of the coronavirus via the oral spray from individuals who might be carrying the virus. The added protection of wearing a mask for those situations when 6-foot distancing is not possible or when someone is hacking and sneezing nearby, undeniably improves our chances of avoiding infection.
However, a new study questions the effectiveness of the 6-foot rule due to their findings that ordinary conversation creates a conical “jet-like” airflow that quickly carries a spray of tiny droplets from a speaker’s mouth much further than 6 feet—meters in fact in distance within confined areas such as the workplace or in stores.
According to a news release from Princeton University, a new study published Sept. 25th in the Proceedings of the National Academy of Sciences by a group of mechanical and aerospace engineers shows that even if an infected person is not sneezing or coughing, just speaking is enough to contaminate an area larger than health experts currently believe is significant.
“People should recognize that they have an effect around them,” said Howard Stone, Professor of Mechanical and Aerospace Engineering at Princeton University. “It’s not just around your head, it is at the scale of meters.”
“Lots of people have written about coughs and sneezes and the kinds of things you worry about with the flu,” Stone said. “But those features are associated with visible symptoms, and with this disease we are seeing a lot of spread by people without symptoms.”
Although the scientists acknowledge that they are not medical experts, their expertize in fluid flow and dynamics warrants serious consideration that the aerodynamic movement of aerosolized particles generated by simply just talking within enclosed spaces could account for the spreading of COVID-19.
Study Shows Speech Spray Goes Further Than Believed
In the study, researchers used a high-speed camera and a sheet of laser light capable of illuminating mists of droplets coming from a person’s face as they speak. The light show revealed the trajectory and spread of the aerosolized breaths as a person spoke several different short phrases like “we will beat the corona virus” to nursery rhymes including “Peter Piper picked a peck” and “Sing a song of six pence.”
The reason for the phrases is that each yields specific puffs of breath that creates a cone-shaped type of jet-like airflow that demonstrates just how aerodynamic breaths can be during conversation.
What the laser light showed was that airflow during speaking could easily and very quickly carry tiny particles away from the speaker significantly further than the current social distancing guidelines; and, in just a matter of seconds.
The researchers also found that the distance achieved depends in part on the duration of the conversation—speaking for more time will send particles farther, and that the public should not think of 6-foot distancing as a wall of protection.
Furthermore, they determined that due to the physics of airflow when indoors, such as at the workplace, in a store or onboard a plane, 6-foot distancing can be nearly meaningless regarding effectiveness in avoiding infection.
“… more extended discussions, and meetings in confined spaces, mean that the local environment will potentially contain exhaled air over a significantly longer distance,” the researchers wrote.
Timothy Boyer has a Ph.D. in Molecular and Cellular Biology from the University of Arizona. For 20+ years he has been employed as a freelance health and science writer. Today, with an eye on the latest news, Timothy continues writing about science with a focus on what you need to know for healthier living. For continual updates about health, you can also follow Timothy on Twitter at TimBoyerWrites.
Image Source: Courtesy of Mohamed Hassan from Pixabay
“Conversation quickly spreads droplets inside buildings” Princeton University News sept. 28, 2020.
“Speech can produce jet-like transport relevant to asymptomatic spreading of virus” Manouk Abkarian, Simon Mendez, Nan Xue, Fan Yang, Howard A. Stone; Proceedings of the National Academy of Sciences; Sept. 2020.