The news: Thousands of droplets from the mouths of people who are talking loudly can stay in the air for between eight and 14 minutes before disappearing, according to a new study. The research, conducted by a team with the US National Institutes of Health and published in PNAS Wednesday, could have significant impact on our understanding of covid-19 transmission.
What’s the point: Respiratory viruses like SARS-CoV-2 are transmitted either by direct contact or when the virus hitches a ride on tiny droplets released into the air by a carrier. That’s why coughing and sneezing are important. But speech can release thousands of oral fluid droplets into the air too, and the researchers were interested in seeing how many were produced and how long they could remain airborne.
The findings: The researchers asked people to repeat phrases and used sensitive lasers to visualize the droplets they produced, watching them decay in a closed, stagnant air environment. On the basis of previous studies of how much viral RNA can be found in oral fluids in the average covid-19 patient, the researchers estimate that a single minute of loud speaking generates at least 1,000 virus-containing droplets. Their observations suggest these droplets stay airborne for longer than eight minutes, and sometimes as long as 14 minutes.