MIT researchers find there is no difference between six or sixty feet in keeping people safe and the more important factor is time spent in a given space.
Additionally, the MIT report has more promising news. The researchers said that, above all else, air flow is the most important factor in reducing pathogen circulation. It doesn’t have to be some expensive air filtration system, either—oftentimes, open windows and air fans will do the trick.
Martin Z. Bazant and John W.M. Bush arrived at their conclusion by using applied mathematics to measure airborne transmission. Their peer-reviewed study, published April 27 in Proceedings of the National Academy of Sciences (U.S.A.), used computer modeling to measure the flow of aerosols and large drop transmission in a “well-mixed” room with a range of factors such as crowd size, ventilation, and “respiratory jets,” like sneezing, to develop new safety guidelines.
“Our study makes clear the inadequacy of the Six-Foot Rule in mitigating indoor airborne disease transmission, and offers a rational, physically informed alternative for managing life in the time of COVID-19,” the authors state.
The authors developed a spreadsheet on suggested exposure time for a variety of indoor settings, and offer an app for easy access.
“What our analysis continues to show is that many spaces that have been shut down in fact don’t need to be,” Bazant told CNBC on April 23. “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.”
Martin Z. Bazant and John W.M. Bush “A Guideline to Limit Indoor Airborne Transmission of COVID-19,” PNAS, April 27, 2021: https://www.pnas.org/content/118/17/e2018995118