Vidcast:  https://youtu.be/MVh9P7Y95GE   In small room or office where a person asymptomatically carrying the CoVid virus has been breathing or occasionally coughing, there may be anywhere from 100,000 to 100 billion copies of live virus hanging in the air to infect you.  This from a pre-published Swiss study just released online.   Coughing but also normal breathing generates aerosols that waft up into the air.  In a closed room, they tend to remain aloft.  Even distancing within the room would lead to you inhaling hundreds of virus copies, enough to infect you.   When you are near a non-family member, it is mandatory that you wear an effective mask filter.   https://www.medrxiv.org/content/10.1101/2020.04.27.20081398v1.full.pdf   https://www.sciencealert.com/here-s-what-we-know-so-far-about-those-who-can-pass-corona-without-symptoms   #covid #coronavirus #aerosols #masks