April 24, 2021
The risk of contracting Covid-19 indoors is the same when socially distanced 6 feet apart and 60 feet apart, researchers at the Massachusetts Institute of Technology (MIT) say.
MIT professors Martin Z. Bazant and John W.M. Bush applied mathematics to the Centers for Disease Control and Prevention and the World Health Organization’s social distancing guidelines. The researchers developed a method of calculating exposure risk to Covid-19 in an indoor setting that considers a variety of factors that could affect the transmission, including 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.
The researchers question the long-held Covid-19 guidelines from the Centers for Disease Control and Prevention and the World Health Organization. The study, published in the Proceedings of the National Academy of Sciences of the United States of America earlier this month, argues the benefits of social distancing are limited at best.
“We argue there really isn’t much of a benefit to the 6-foot rule, especially when people are wearing masks,” Bazant told CNBC. “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.”
Time is key, researchers say
Bazant says a key variable overlooked by the CDC and the WHO is the amount of time spent indoors. The longer someone is inside with an infected person, the greater the chance of transmission, he said.
Bazant asserts that indoor occupancy caps are flawed because they fail to take into account exposure time and the size of the space.
“What our analysis continues to show is that many spaces that have been shut down in fact don’t need to be. Oftentimes, 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.”
Bazant argues that the six-feet social distancing rules are “just not reasonable.”
“Above all, our study makes clear the inadequacy of the SixFoot Rule in mitigating indoor airborne disease transmission, and offers a rational, physically informed alternative for managing life in the time of COVID-19.”A guideline to limit indoor airborne transmission of COVID-19
“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.
Bazant also claims that opening windows or installing new fans to keep air moving may be just as effective or more effective than purchasing complex filtration systems.
After three rounds of peer review, Bazant says he hopes the study will influence social distancing policies.