We can think about coronavirus-transmission if it were passive smoking (but far more deadly). We already know how to visualise this (we have a good mental picture of the way smoke moves) and understand how to mitigate it (distance, fresh air). But too many people misunderstand how the virus spreads, and so they do what they think is most obvious. Poor public-health information, which omits this factor, makes most people focus primarily on frequent hand and surface sanitisation. Sanitisation is a good idea, but it is not as important as ventilation.