Supreme Court turns down govt plea to re-open NRC process in Assam

London, May 20: The current physical distancing guidelines of 6 feet may be insufficient to prevent COVID-19 transmission, according to a study which says a mild cough in low wind speeds can propel saliva droplets by as much as 18 feet.

Researchers, including those from the University of Nicosia in Cyprus, said a good baseline for studying the airborne transmission of viruses, like the one behind the COVID-19 pandemic, is a deeper understanding of how particles travel through the air when people cough.

In the study, published in the journal Physics of Fluids, they said even with a slight breeze of about four kilometres per hour (kph), saliva travels 18 feet in 5 seconds.

"The droplet cloud will affect both adults and children of different heights," said study co-author Dimitris Drikakis from the University of Nicosia.

According to the scientists, shorter adults and children could be at higher risk if they are located within the trajectory of the saliva droplets.

They said saliva is a complex fluid, which travels suspended in a bulk of surrounding air released by a cough, adding that many factors affect how saliva droplets travel in the air.

These factors, the study noted, include the size and number of droplets, how they interact with one another and the surrounding air as they disperse and evaporate, how heat and mass are transferred, and the humidity and temperature of the surrounding air.

In the study, the scientists created a computer simulation to examine the state of every saliva droplet moving through the air in front of a coughing person.

The model considered the effects of humidity, dispersion force, interactions of molecules of saliva and air, and how the droplets change from liquid to vapour and evaporate, along with a grid representing the space in front of a coughing person.

Each grid, the scientists said, holds information about variables like pressure, fluid velocity, temperature, droplet mass, and droplet position.

The study analysed the fates of nearly 1,008 simulated saliva droplets, and solved as many as 3.7 million equations.

"The purpose of the mathematical modelling and simulation is to take into account all the real coupling or interaction mechanisms that may take place between the main bulk fluid flow and the saliva droplets, and between the saliva droplets themselves," explained Talib Dbouk, another co-author of the study.

However, the researchers added that further studies are needed to determine the effect of ground surface temperature on the behaviour of saliva in air.

They also believe that indoor environments, especially ones with air conditioning, may significantly affect the particle movement through air.

This work is important since it concerns safety distance guidelines, and advances the understanding of the transmission of airborne diseases, Drikakis said.

Bengaluru, Jul 17: Bruhat Bengaluru Mahanagara Palike (BBMP) Mayor, M Goutham Kumar on Friday called for an extension of lockdown in the city for one more week due to rise in the COVID-19 cases.

"It will be better if we get more time to tackle COVID-19 cases, we wish for the extension of lockdown for one more week. We have given the proposal to the government," said M Goutham Kumar, BBMP Mayor.

"After the number of cases increased in Bengaluru, BBMP started antigen test in containment and hotspot zones of Bengaluru to tackle the cases which have crossed 2,000 mark," he added.

Along with Mayor, BBMP Commissioner Anil Kumar has also proposed the state government to extend lockdown in Bengaluru for one more week.

"The number of cases in Bengaluru increasing in Bengaluru rapidly. BBMP has inaugurated more than 200 vehicles in Bengaluru for the use of the antigen test," said Anil Kumar, Commissioner BBMP.

According to the Union Health Ministry, there are 51,422 COVID-19 cases in the state.