- Microdroplets less than 100th of millimetre in size may spread the coronavirus.
- Research in Japan shows microdroplets can remain in the air for 20 minutes in enclosed spaces.
- Opening a window or a door can eliminate the droplets.
We’ve all heard the advice about catching sneezes and coughs in a tissue to avoid spreading coronavirus. But new research from Japan suggests that infection could be spread by simply holding a conversation with another person.
Using high-definition cameras and laser lighting, NHK, Japan’s public broadcaster, conducted an experiment with a group of researchers to capture the movement of microdroplets – particles that are less than 100th of a millimetre in size.
They found these microdroplets are emitted every time we speak – and the louder we talk, the more are emitted. So, two people holding a conversation at a normal distance apart could easily lead to infection.
The findings underline the social distancing message from the World Health Organization, which advises people to keep at least 1 metre apart at all times. It also reinforces the need to keep rooms well-ventilated.
A floating threat
The research sheds new light on the rapid spread of coronavirus. Previous studies focused on sneezes and coughs, which emit larger 1 millimetre droplets that can be seen using a normal camera.
NHK found that droplets from a sneeze fall quickly to the ground and do not travel very far, even in still air. But their cameras also picked up microdroplets, less than 100th of a millimetre across.