Here is an excellent demo of how Covid can spread given different precautions. It is found on the El Pais English website. Those of us who open the window in the Albergue can now swagger about with great authority.
The risk of contagion is highest in indoor spaces but can be reduced by applying all available measures to combat infection via aerosols. Here is an overview of the likelihood of infection in three everyday scenarios, based on the safety measures used and the length of exposure