Covid- 19 - Why 2m Social Distancing?

11th Apr 2020

It is still not fully understood how viruses, such as the common flu are transmitted and that has been subject to many years of study.   It is commonly accepted that the more symptomatic a person is, the more virus they will shed and with other forms of coronavirus a symptomatic person can release 100 million virus particles in a single millilitre of fluid.  It is thought that exposure to a little as a few hundred particles, can lead to contracting the disease. It is known that people can have Covid-19 and have very mild or no symptoms and can be shedding the virus.  A major route of shedding is via aerosols created, when breathing, talking, sneezing or coughing.  One study showed that a subject counting from 1 to 100, released ten times more aerosol than one cough or sneeze, therefore talking to someone for 2 minutes, at usual separation, is nearly as bad as having them cough or seeze directly in your face.  Coupled with the fact that talking created finer droplets than sneezing or coughing makes the hazard less obvious.  A significant proportion of the aerosol is below 100µm diameter (width of a human hair) and evaporates and/or fall to the ground within 1.5m when emitted from an average sized adult as a cough.