IMF calls for 'urgent' action by India amid slowdown

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.

Lucknow, Jan 21: Defending his brainchild, the Citizenship Amendment Act (CAA), Union home minister Amit Shah on Tuesday said the new law will not be scrapped despite the countrywide protests against it.

Addressing a rally here to drum up support for the CAA, Shah also declared that construction of a Ram temple "touching the skies" in Ayodhya will begin within three months.

He said there is no provision in the amended law for taking anyone's citizenship away. "A canard is being spread against the CAA by the Congress, SP, BSP, and Trinamool Congress. The CAA is a law to grant citizenship," he added.

"I want to say that irrespective of the protests this will not be withdrawn," he added.

Shah challenged Congress leaders to hold a discussion with him on CAA at a public forum.

He named Congress leader Rahul Gandhi, Samajwadi Party's Akhilesh Yadav, Bahujan Samaj Party's Mayawati and TMC chief Mamata Banerjee while throwing the "challenge".

Congress has become blind due to vote bank politics,"he said. He also blamed the Congress for Partition.