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Dubai, Jun 15: The global tally of Covid-19 coronavirus infections crossed the 8 million mark on Monday, with recoveries at 4.13 million, and deaths at nearly 436,000.

As of 11.40am UAE time, there were 3.43 active Covid-19 cases globally, of which 54,460 were serious or critical.

The United States still leads the charts with 2.16 million cases and 117,858 deaths. Behind US, at a distant No 2, is Brazil with 867,882 cases and 43,389 deaths.

Russia, India, the UK, Spain, Italy, Peru, Germany and Iran complete the top 10.

May 15: Global deaths linked to the novel coronavirus passed 300,000 on Thursday, while reported cases of the virus are approaching 4.5 million, according to a news agency tally.

About half of the fatalities have been reported by the United States, the United Kingdom and Italy.

The first death linked to the disease was reported on January 10 in Wuhan, China. It took 91 days for the death toll to pass 100,000 and a further 16 days to reach 200,000, according to the Reuters tally of official reports from governments. It took 19 days to go from 200,000 to 300,000 deaths.

By comparison, an estimated 400,000 people die annually from malaria, one of the world’s most deadly infectious diseases.

The United States had reported more than 85,000 deaths from the new coronavirus, while the United Kingdom and Italy have reported over 30,000 fatalities each.

While the current trajectory of COVID-19 falls far short of the 1918 Spanish flu, which infected an estimated 500 million people, killing at least 10% of patients, public health experts worry the available data is underplaying the true impact of the pandemic.

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.