How long does a Covid-19 virus-carrying droplet last? It depends on factors such as the ambient temperature, size, angle at which it is distributed and humidity.
Fluid dynamics play an important role in studying the life of these droplets migrating in the air or deposited on a surface.
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A study by the Indian Institute of Information Technology (IIT-H) has found that the spread of the virus is minimal after the droplets containing the virus have dried up.
Another key way away from the study is that droplets last much longer on a smartphone screen than on a normal glass surface.
“The drying time for droplets on a smartphone screen is three times longer than on a normal glass surface,” said the study, conducted by an interdisciplinary research group.
Researchers at IIT-H performed the study to predict the life of the SARS-COV-2 droplet in different environmental conditions.
Respiratory infections such as the SARS-CoV-2 virus are spread mainly by saliva droplets or released from the nose of an infected person during coughing or sneezing.
Saliva droplets contain salt, protein (mucin), and surfactant (dipalmitoylphosphatidylcholine) as well as water.
“These ingredients significantly delay the evacuation of breath droplets compared to fresh water drops,” said the researchers.
Any increase in humidity of the droplet will take more than an hour to dry compared to a droplet under a lower humid environment that dries in minutes.
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“The lower ambient temperature will also increase the droplet drying time. An angle made by a droplet on the surface (called a contact angle) plays an important role in the droplet’s drying time, ”the study found.
The multidisciplinary study was conducted by Saravanan Balusamy, Sayak Banerjee (Department of Mechanical Engineering and Aerospace) and Kirti Chandra Sahu (Department of Chemical Engineering).
The findings of the research appeared in the International Conference on Heat Transfer and Mass Transfer, a leading journal in this field.
“The time it takes for saliva droplets to dry also depends on the nature of the surface material on which it falls as it determines how long the droplet will spread out,” said Sayak Banerjee.
“As long as a small droplet of saliva of size 1 nanolitre lasts less than a minute, a drop of saliva of a typical size of 10 nanolitres will take more than 15 minutes to evacuate at room temperature and 50 percent relative humidity,” said Kirti Chandra Sahu , said.
The longest drying times are monitored by the combination of low ambient temperature and relatively high humidity, while the drying time gradually decreases as the humidity drops and the temperature decreases. rising.