Researchers at the Massachusetts Institute of Technology (MIT) in Cambridge, US, used high-speed cameras and other sensors to assess precisely what happens after a cough or sneeze. They found that an exhalation generates a small fast-moving cloud of gas that can contain droplets of liquid of varying sizes – and that the smallest of these can be carried in the cloud over long distances. The study found that coughs can project liquid up to 6m away and that sneezes, which involve much higher speeds, can reach up to 8m away. The scientist who led the study, Prof Lydia Bourouiba of MIT, told me that she is concerned about the current concept of “safe distances”.
“What we exhale, cough or sneeze is a gas cloud that has high momentum that can go far, traps the drops of all sizes in it and carries them through the room,” she said. “So having this false idea of safety at one to two metres, that somehow drops will just fall to the ground at that distance is not based on what we have quantified, measured and visualised directly.” By David Shukman Science editor BBC
The above article was published today on BBC News online. This is frightening. We have been told since the start of this Pandemic that we don’t need to wear a surgical mask unless we are infected or caring for an infected person. Now, a month on, the WHO may be telling us that they have changed their minds and that may be wearing a mask may be as effective as distancing.
“it might be that wearing a mask is equally as effective or more effective than distancing.”
The World Health Health Organisation will let us know their decision tonight.