Hundreds of Scientists Warn COVID-19 Is Airborne, And WHO Needs to Act - ScienceAlert

"There is significant potential for inhalation exposure to viruses in microscopic respiratory droplets (microdroplets) at short to medium distances (up to several meters, or room scale)," wrote the authors, led by Lidia Morawska of the Queensland University of Technology.

Cath Noakes, a professor of environmental engineering for buildings at the University of Leeds, who contributed to the paper, said COVID-19 doesn't spread in the air as easily as measles or tuberculosis, but is a threat nonetheless.

The authors recognized that the evidence for microdroplet transmission was "admittedly incomplete," but argued that the evidence for large droplets and surface transmission was also incomplete yet still formed the basis for health guidelines.

Put another way, "absence of evidence is not evidence of absence," said Julian Tang, an associate professor of respiratory sciences at the University of Leicester who contributed to the commentary.

"The WHO say that there is insufficient evidence to prove aerosol/airborne transmission of SARS-CoV-2 is happening.