‘Tiny airborne droplets produced through speech can linger in the air for longer than 10 minutes – and may be potentially significant in the spread of coronavirus, research suggests.
Scientists have found that loud speech can emit thousands of oral fluid droplets per second.
The study, from researchers at the National Institute of Diabetes and Digestive and Kidney Diseases and the University of Pennsylvania, was published in the Proceedings of the National Academy of Sciences journal.
It is based on an experiment which used laser light to analyse the number of small respiratory droplets emitted through human speech.
In a closed, stagnant air environment, the droplets disappear from the window of view with time constants in the range of eight to 14 minutes, researchers say.
They write: “These observations confirm that there is a substantial probability that normal speaking causes airborne virus transmission in confined environments.”
The research did not involve the coronavirus or any other virus, but looked at how people generate respiratory droplets when they speak.
It focused on small droplets that can linger in the air much longer.
According to the researchers, these droplets still could potentially contain enough virus particles to represent an infectious dose.
They say the probability that speech droplets pass on an infection when emitted by a virus carrier must take into account how long the droplet remains airborne.’