On March 28, 2020, at the beginning of the pandemic, the World Health Organization (WHO) tweeted out, “FACT: #COVID19 is NOT airborne.”
For medical doctors and biomedical scientists (including me), this made sense. Few diseases were known to be airborne.
But to aerosol scientists, this was both puzzling and infuriating.
Over the next two years, the WHO and other organizations that had initially denied that the new coronavirus could stay in the air and move around like smoke quietly changed their stance.