A study co-authored by two MIT professors has found that staying six feet apart while indoors does little to reduce the risk of COVID-19 transmission among groups of people with mixed vaccination statuses.
The researchers said COVID-19 is primarily spread through small aerosol droplets, not larger droplets as health experts initially warned during the early stages of the pandemic. Small aerosol droplets can stay suspended in the air for extended periods of time and disperse more evenly throughout a room.
Based on this new knowledge, the study authors said the recommendation of staying six feet apart while indoors isn’t particularly effective at reducing the risk of COVID-19 spread. They say small aerosol droplets can still work their way through a room pretty easily and remain there for some time.
How long the virus floats in the air
The MIT researchers created a model showing how long the particles that cause COVID-19 can stay in the air in different indoor scenarios.
In a calm environment, the authors said small aerosol droplets would slowly drift to the ground. In a room filled with people that are talking, eating, singing, and sneezing, the droplets can be suspended in the airflow and mixed throughout the room for a longer period of time.
Increasing the ventilation or air filtration can help mitigate the transmission risk in these types of environments by getting the particles out of the air, the researchers said. Their model that shows indoor transmission risk can be viewed here.
Masks and ventilation crucial
The researchers stressed that people should still avoid very crowded indoor situations when possible, and they should wear masks if it’s necessary to be in a densely populated area.
“To minimize risk of infection, one should avoid spending extended periods in highly populated areas,” the researchers said. “One is safer in rooms with large volume and high ventilation rates.”
Individuals are “at greater risk in rooms where people are exerting themselves in such a way as to increase their respiration rate and pathogen output, for example, by exercising, singing, or shouting,” the study authors added. They concluded by saying that wearing masks can reduce the risk of transmission.