A new study has found that coronavirus may be spreading through talking. This could explain the spread of the virus even before people develop a chough. When we speak we produce thousands of tiny oral droplets.
Researchers detected SARS-CoV-2 in speech droplets of infected people. The test subjects were asymptomatic carriers of SARS-CoV-2. The microdroplets remained airborne for 8-14 minutes in a closed space.
To see if virus particles are present in speech droplets during normal conversation researchers asked volunteers to repeat the words “stay healthy” in a closed box. The inside of the box was painted black and illuminated with green lasers. That tracked bursts of droplets produced by the speaker.
Results showed that talking produces about 2,600 droplets per second. Speaking loudly generates larger and more quantity of droplets. Based on their estimates, researchers calculated that speaking loudly for one minute could generate around 1,000 virus-containing droplets from an asymptomatic person.
The droplets could remain airborn for about 14 minutes. This suggests that a person does not necessarily have to cough or sneeze to transmit a respiratory virus like the COVID19 coronavirus to others.
Researchers are not sure if tiny speech droplets infect more people than larger cough droplets. Also, it is not clear et how may viral particles must be inhaled by a person to become infected. This is known as the minimal infectious dose.
The experiment was performed in a closed space without ventilation. Indoor spaces with poor ventilation pose a higher risk than outdoor ones. In China, researchers found fewer aerosols in isolation wards and patient rooms with good ventilation and thorough sanitization. However, higher levels of airborne viral particles were found in closed spaces.
Such as patients’ toilet arears or rooms where medical workers remove protective gear. It was previously thought that SARS-CoV-2 is transmitted through droplets generated by coughing or sneezing. A single cough can produce about 3,000 respiratory droplets. While sneezing can generate as many as 40,000 respiratory droplets.
These droplets may fall on other surfaces such as doorknobs. An uninfected person may touch the surface and become infected. To determine how speech and breathing contribute to COVID-19 transmission information about the movement of droplets in defferent environmental conditions is also important.