Nine months into the COVID-19 pandemic, we all know the rules of social distancing by now: Stay at least six feet apart and don’t forget to mask up when around other people. But as the weather turns colder, many of us have been forced to halt our socially distanced get togethers — not to mention meetings and events at outdoor venues. According to MIT researchers, anyone planning to hold indoor gatherings in the coming months should be aware of a key risk factor that physical distance and masks can’t help — the amount of time spent with others who could be contagious.
In a recent Fast Company article, John Bush, professor of applied mathematics at Massachusetts Institute of Technology (MIT), called our now familiar social-distancing rules overly simplistic when it comes to indoor settings. “Because when you’re inside, microscopic droplets are trapped right alongside you in a confined space,” wrote the Fast Company article’s author, Mark Wilson, “and standing six feet away from someone doesn’t stop the SARS-CoV-2 virus from floating in the air of your living room where you can potentially inhale it.”
To help determine the level of risk in different indoor scenarios — including a classroom, suburban home, restaurant, or a Boeing 737 — Bush and fellow MIT colleague Martin Z. Bazant created an online tool, COVID-19 Indoor Safety Guideline. The tool works on the assumption that one person in the room has COVID-19 and uses a complex mathematical model to simulate infection rates based on such factors as room size, the speaking volume of its inhabitants, the air filtration system in use, and more. Users are able to assess the risk of transmission by plugging in their own parameters.
I tested the tool myself to learn more about the safety of a meeting room setup. I set up the following parameters:
- a standard 1,500-square-foot meeting room with 14-foot ceilings (a common size for convention center breakout rooms), using mechanical ventilation and a MERV 10 filtration system, which is slightly better than a standard filtration system
- an average relative humidity rate of 60 percent
- 50 attendees, 95 percent of whom are properly wearing coarse cotton masks, with resting exertion levels and talking normally as the respiratory activity
Under these conditions, the tool calculated, the meeting space could safely accommodate those 50 attendees for a mere 32 minutes. And that is assuming that just one of the 50 people in the room is contagious.
“At first glance, all of these controls might seem overwhelming. (And they are!)” Wilson wrote. “But the payoff is worth it. Because the tool gives you a very clear answer of how long how many people can safely be in a space together.”