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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.

Mumbai, Mar 5: Jet Airways founder Naresh Goyal and few others have been booked by the ED in a money laundering case even as the agency is conducting searches at his premises, officials said on Thursday.

They said a criminal case against the former chairman of the airlines has been filed under the Prevention of Money Laundering Act (PMLA) after taking cognisance of a recent Mumbai Police FIR filed against him.

The Enforcement Directorate carried out raids at Goyal's premises in Mumbai on Wednesday and also questioned him after filing the case, they said.

The action is continuing, they added.

The Mumbai Police FIR pertains to charges of alleged fraud by Goyal and others against a Mumbai-based travel company.

Goyal has earlier been grilled by the central probe agency in a case filed under the Foreign Exchange Management Act (FEMA) in September last year.

The agency had carried out similar raids, under the FEMA, in August last year against Goyal, his family and others.

ED has alleged in the past that the businessman's empire had 19 privately-held companies, five of which were registered abroad.

The agency is probing charges that these firms allegedly carried out “doubtful” transactions under the guise of selling, distribution and operating expenses.

The ED suspects that expenses at these companies were allegedly booked at fake and high costs and as a result, they “projected” huge losses.

Alleged shady aircraft lease transactions with non-existent offshore entities are also under the ED scanner and it is suspected that Jet Airways made payments for lease rental to “ghost firms”, which purportedly routed the ill-gotten money in Goyal's companies.

A full-service carrier, Jet Airways shut its operations in April last year after running out of cash.

A month earlier, Goyal had stepped down as the chairman of Jet Airways.