The Covid-19 pandemic has already wrecked millions of lives. According to an MIT (Massachusetts Institute of Technology) study, people who keep a social distance of 60 feet from others indoors are no more protected from Covid-19 than those who keep a social distance of 6 feet.
The study challenges the global social distancing recommendations, the chance of being exposed to Covid-19 indoors is the same at 60 feet as it is at 6 feet — even while wearing a mask.
Martin Z. Bazant, who teaches chemical engineering and applied mathematics at MIT, and John W.M. Bush, who teaches applied mathematics, developed a method for calculating Covid-19 exposure risk in an indoor space, the amount of time spent inside, air filtration and circulation, immunization, variant strains, mask use, and even respiratory activity such as breathing, eating, speaking, or singing are all factors that could influence transmission.
In a peer-reviewed study published earlier this week in Proceedings of the National Academy of Science of the United States of America, Bazant and Bush cast doubt on long-held Covid-19 recommendations from the Centers for Disease Control and Prevention and the World Health Organization.
“We argue there really isn’t much of a benefit to the 6-foot rule, especially when people are wearing masks,” Bazant said in an interview. “It really has no physical basis because the air a person is breathing while wearing a mask tends to rise and comes down elsewhere in the room so you’re more exposed to the average background than you are to a person at a distance.”
The amount of time spent indoors is a significant variable that the CDC and WHO have ignored, according to Bazant. According to him, the longer someone is inside with an infected person, the greater the risk of transmission.
Keeping the air moving by opening windows or adding new fans might be just as effective as or more effective than investing in a new filtration device, he said.
Bazant also claims that the rules governing the enforcement of indoor occupancy limits are flawed. He said 20 people gathering inside for one minute would probably be perfect, but not for many hours.
“What our analysis continues to show is that many spaces that have been shut down in fact don’t need to be. Often times the space is large enough, the ventilation is good enough, the amount of time people spend together is such that those spaces can be safely operated even at full capacity and the scientific support for reduced capacity in those spaces is really not very good,” Bazant said. “I think if you run the numbers, even right now for many types of spaces you’d find that there is not a need for occupancy restrictions.”
According to Bazant, six-foot social distancing laws that unwittingly close businesses and schools are “just not reasonable.”
“This emphasis on distancing has been really misplaced from the very beginning. The CDC or WHO have never really provided justification for it, they’ve just said this is what you must do and the only justification I’m aware of, is based on studies of coughs and sneezes, where they look at the largest particles that might sediment onto the floor and even then it’s very approximate, you can certainly have longer or shorter range, large droplets,” Bazant said.
“The distancing isn’t helping you that much and it’s also giving you a false sense of security because you’re as safe at 6 feet as you are at 60 feet if you’re indoors. Everyone in that space is at roughly the same risk, actually,” he added.
When people speak, breathe, or eat, pathogen-laced droplets move through the air indoors. In comparison to the early months of the pandemic, when hand-washing was the leading recommendation to prevent transmission, it is now understood that airborne transmission plays a significant role in the spread of Covid-19.
Those droplets from one’s warm exhalation mix with body heat and air currents in the area to rise and travel throughout the entire room, no matter how socially distanced a person is. People seem to be more exposed to that “background” air than they are by droplets from a distance, according to the study.
For example, in an enclosed space where someone infected with Covid-19 is wearing a mask and singing loudly, a person sitting on the opposite side of the room is no more safe than someone sitting six feet away. This is why the amount of time spent in the enclosed space is more significant than the distance between you and the infected individual.
Masks act to avoid transmission by blocking larger droplets, so larger droplets aren’t the source of most Covid infections since most people are wearing masks. The bulk of people who are transmitting Covid are asymptomatic, meaning they aren’t coughing or sneezing.
Indoor transmission is often prevented by masks by blocking direct plumes of air, which can be visualized by imagining someone exhaling smoke. Constant exposure to infectious air plumes will increase the risk of transmission, though direct exhaled air plume exposure does not normally last long.
Those that are in the vicinity are heavily impacted by secondhand smoke that finds its way around the enclosed area and lingers, even with masks on. According to the analysis, the same logic applies to infectious airborne droplets. When transmitting indoors and masked, factors other than distance may be more important to remember.
Outdoor social distancing, according to Bazant, makes absolutely no sense, and doing so while wearing masks is “kind of crazy.”
“If you look at the air flow outside, the infected air would be swept away and very unlikely to cause transmission. There are very few recorded instances of outdoor transmission.” he said. “Crowded spaces outdoor could be an issue, but if people are keeping a reasonable distance of like 3 feet outside, I feel pretty comfortable with that even without masks frankly.”
This may explain why transmission hasn’t spiked in states like Texas or Florida where businesses have reopened without capacity restrictions, he said.
In the case of 60 percent more transmissible variant strains, improving ventilation by 60 percent, reducing the amount of time spent inside, or decreasing the number of people inside could all help to mitigate the risk.
Bazant also stated that when masks should be removed would be a major issue, and that the study’s recommendations will help measure the risks. He also mentioned that measuring carbon dioxide levels in a room will help determine how much infected air is present and thus the risk of infection.
“We need scientific information conveyed to the public in a way that is not just fearmongering but is actually based in analysis,” he also added. After three rounds of heavy peer review, he said it’s the most review he’s ever been through, and that now that it’s published he hopes it will influence policy.