Speech droplets from people talking loudly in confined spaces could result in coronavirus remaining in the air for more than eight minutes at least, according to a new study by researchers from the US National Institutes of Health.

Researchers used an intense sheet of laser light to visualize bursts of speech droplets produced during repeated spoken phrases. Researchers achieved this by having volunteers repeat the phrase “stay healthy” for 25 seconds. The phrase was chosen because the “th” sound in the word “healthy” was found to be an efficient generator of oral fluid speech droplets.

They found that loud speech can emit thousands of oral fluid droplets per second.

“In a closed, stagnant air environment, they disappear from the window of view with time constants in the range of 8 to 14 min,” read the abstract of the research, published in the open-access journal Proceedings of the National Academy of Sciences (PNAS).

“These observations confirm that there is a substantial probability that normal speaking causes airborne virus transmission in confined environments,” the researchers added.

The new research study is important as it raises questions whether the mere act of an infected patient talking loudly could be a factor in transmitting the coronavirus to other people.

According to the World Health Organization, the COVID-19 coronavirus spreads primarily through droplets of saliva or discharge from the nose when an infected person coughs or sneezes.

The novel coronavirus has killed at least 294,199 people since the outbreak first emerged in China last December, according to a tally from official sources compiled by AFP.