This archive report was first published on 15 May 2020.
Published on May 15, 2020, a study by researchers at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) has shed light on the potential spread of COVID-19 through speech.
According to the study, which was published in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS), microdroplets generated by speech can remain suspended in the air for more than 10 minutes in an enclosed space.
Researchers conducted an experiment where a person loudly repeated the phrase 'Stay healthy' for 25 seconds inside a closed box. A laser was used to illuminate the droplets, allowing them to be seen and counted.
The study found that the droplets stayed in the air for an average of 12 minutes. Taking into account the known concentration of coronavirus in saliva, scientists estimated that each minute of loudly speaking can generate more than 1,000 virus-containing droplets capable of remaining airborne for eight minutes or more in a closed space.
As the researchers conclude, 'This direct visualization demonstrates how normal speech generates airborne droplets that can remain suspended for tens of minutes or longer and are eminently capable of transmitting disease in confined spaces.'
