So for aerosol spread diseases if you are in a room with an infected person in 4 hours you probably have it too. Masks (which people are stopping wearing) and ventilation (which energy-efficient buildings don't have) turn it into hit or miss.
https://english.elpais.com/society/2020-10-28/a-room-a-bar-and-a-class-how-the-coronavirus-is-spread-through-the-air.html
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May 22, 2021