This archive report was first published on 6 July 2020.
Published on July 6, 2020, a commentary in the Oxford Academic journal Clinical Infectious Diseases shed light on the airborne transmission of COVID-19. Researchers led by Lidia Morawska of the Queensland University of Technology concluded that viruses can travel tens of meters in the air, and analyses of certain spreading events had demonstrated the same was true of the SARS-CoV-2 virus that causes COVID-19.
According to the authors, hand washing and social distancing are insufficient to provide protection from virus-carrying respiratory microdroplets released into the air by infected people. They recommended greater ventilation for indoor environments, the introduction of high efficiency air filters and ultraviolet lamps, and avoiding overcrowding in buildings and on public transport.
When an infected person coughs or sneezes, they expel droplets of various sizes. Those above five to ten micrometers fall to the ground quickly within a meter or two, while droplets under this size can become suspended in the air in what is called an aerosol, remaining aloft for far longer and traveling further.
There has been a vigorous debate in the scientific community about how infectious microdroplets are in the context of COVID-19. However, studies of particular spreading events have shown that microdroplet transmission isn't limited to hospitals.
For instance, a study in Emerging Infectious Diseases found that the air flow from an air conditioning unit appeared to waft the coronavirus to several tables in a Chinese restaurant in January where patrons became infected.
The authors of the commentary recognized that the evidence for microdroplet transmission was incomplete, but argued that the evidence for large droplets and surface transmission was also incomplete yet still formed the basis for health guidelines.
Following the precautionary principle, they urged that every potentially important pathway to slow the spread of COVID-19 must be addressed.
