There is No Difference Between 6 Feet Or 60 Feet Indoors In Getting Infected With SARS-CoV-2 Even With Mask On According To MIT Airborne Study
A new MIT SARS-CoV-2 airborne transmission study findings challenges the current rules of social distancing.
It was found that the risk of being exposed to Covid-19 indoors is as great at 60 feet as it is at 6 feet even when wearing a mask, according to a new study by Massachusetts Institute of Technology researchers who challenge social distancing guidelines adopted across the world.
Professors Martin Z. Bazant, who teaches chemical engineering and applied mathematics, and John W.M. Bush, who teaches applied mathematics, developed a method of calculating exposure risk to Covid-19 in an indoor setting that factors in a variety of issues that could affect 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.
Both professors question long-held Covid-19 guidelines from the U.S.CDC and the WHO in a peer-reviewed study published earlier this week in Proceedings of the National Academy of Science of the United States of America. https://www.pnas.org/content/118/17/e2018995118
Professor Bazant told Thailand Medical News, “We argue there really isn’t much of a benefit to the 6-foot rule, especially when people are wearing masks. 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.”
It was reported that the key variable the CDC and the WHO have overlooked is the amount of time spent indoors, Bazant said. The longer someone is inside with an infected person, the greater the chance of transmission, he said.
Also opening windows or installing new fans to keep the air moving could also be just as effective or more effective than spending large amounts of money on a new filtration system, he said.
Professor Bazant also says that guidelines enforcing indoor occupancy caps are flawed. He said 20 people gathered inside for 1 minute is probably fine, but not over the course of several hours, he said.
He added, “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. 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 Professor Bazant, six-feet social distancing rules that inadvertently result in closed businesses and schools are “just not reasonable.”
He further added,“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, larg
He noted, “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.”
It was found that pathogen-laced droplets travel through the air indoors when people talk, breathe or eat. It is now known that airborne transmission plays a huge role in the spread of Covid-19, compared with the earlier months of the pandemic where hand-washing was considered the leading recommendation to avoid transmission.
According to the study, 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.
As an example, if someone infected with Covid-19 is wearing a mask and singing loudly in an enclosed room, a person who is sitting at the other side of the room is not more protected than someone who is sitting just six feet away from the infected person. This is why time spent in the enclosed area is more important than how far you are from the infected person.
Although masks work in general to prevent transmission by blocking larger droplets, therefore larger droplets aren’t making up the majority of Covid infections because most people are wearing masks. The majority of people who are transmitting COVID aren’t coughing and sneezing, they’re asymptomatic.
Also masks work to prevent indoor transmission by blocking direct plumes of air, best visualized by imagining someone exhaling smoke. Constant exposure to direct plumes of infectious air would result in a higher risk of transmission, though exposure to direct plumes of exhaled air doesn’t usually last long.
It was said that even with masks on, as with smoking, those who are in the vicinity are heavily affected by the secondhand smoke that makes its way around the enclosed area and lingers. The same logic applies to infectious airborne droplets, according to the study. When indoors and masked, factors besides distance can be more important to consider to avoid transmission.
With regards to social distancing outdoors, Professor Bazant says it makes almost no sense and that doing so with masks on is “kind of crazy.”
He said, “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. 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.”
Professor Bazant says this could possibly explain why there haven’t been spikes in transmission in states like Texas or Florida that have reopened businesses without capacity limits.
The study reported that as for variant strains that are 60% more transmissible, increasing ventilation by 60%, reducing the amount of time spent inside or limiting the number of people indoors could offset that risk.
Professor Bazant also said that a big question that is coming will be when masks can be removed, and that the study’s guidelines can help quantify the risks involved. He also noted that measuring carbon dioxide in a room can also help quantify how much infected air is present and hence risk of transmission.
Professor Bazant said, “We need scientific information conveyed to the public in a way that is not just fearmongering but is actually based in analysis. 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 public health policies.
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