Understanding masks and distancing for COVID-19

The current rules on distancing (1m or 2m) and wearing of masks indoor and outdoor are creating some confusions among the public.

In fact the risk of COVID-19 contagion via airborne particle is better understood now and as we go back to work and try to resume a normal life, it is important for everyone to understand that the risk of contagion are dependent primarily on:

  • whether people are wearing masks
  • air ventilation, whether outdoor or indoor
  • proximity between people, density of people
  • amount of air exhaled ie whether people are silent, speaking or shouting/singing
  • the length of interaction between people

And while this seems too complicated, it is quite intuitive and can form the basis of a better prevention and clearer understanding of the purpose of these restrictions.

This was studied in great details in a recent article in  the British Journal of Medicine reviewing the evidence for physical distancing: click here

To sum it up:

 

Note: the 'super spreader' phenomenon is not fully understood yet but it appears that some people generate a much higher viral load while shouting or coughing and this is a significant though rare factor in the transmission risk.