Epic nuclear case: Island nation takes on India, Pak, Britain

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.

Hubei, Mar 25: As a bus departed from its terminus at Hankou Railway Station at 5:25 am Wednesday morning, Wuhan started to resume bus service after nine weeks of lockdown.

Apart from a driver, a safety supervisor was also on each bus, whose duty was to make sure all passengers are healthy.
"For those who do not use smartphones, they should bring with them a health certificate issued by the health authorities," said Zhou Jingjing, a safety supervisor aboard bus No. 511 departing from the Wuchang Railway Station complex.
The once hardest-hit city in central China's Hubei Province during the COVID-19 outbreak took unprecedented traffic restrictions on Jan 23. All of its public transport and all outbound flights and trains had been suspended in an attempt to contain the virus within the region.

London, Mar 25: Prince Charles on Wednesday has tested positive for the novel coronavirus and is working from home with mild symptoms, according to UK media.
A Clarence House spokesperson said the Prince of Wales was "displaying mild symptoms but otherwise remains in good health and has been working from home throughout the last few days as usual", the Telegraph UK reported.
"He has been displaying mild symptoms but otherwise remains in good health and has been working from home throughout the last few days as usual," the spokesperson added.
In accordance with the government and medical advice, the 71-year old heir to the British throne and Camilla, the Duchess of Cornwall, are now self-isolating at their home in Scotland.
The Duchess of Cornwall has also been tested but does not have the virus.
The tests were carried out by the NHS in Aberdeenshire where they met the criteria required for testing.
"It is not possible to ascertain from whom the Prince caught the virus owing to the high number of engagements he carried out in his public role during recent weeks," the statement further said.