This Japanese experiment shows how easily coronavirus can spread – and what you can do about it

  • 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.

www.weforum.org/agenda/2020/04/coronavirus-microdroplets-talking-breathing-spread-covid-19/