Varavara Rao tests coronavirus positive

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, Feb 27: Defence Minister Rajnath Singh on Thursday said that the situation is moving towards normalcy in Delhi after recent incidents of violence.

"Situation is moving towards normalcy," Rajnath told media here.

Joint Commissioner of Police (Traffic) Narendra Singh Bundela on Thursday said that the law and order and traffic situation in violence-affected parts of Delhi is normal.

"The situation is quite normal and peaceful as far as security and traffic are concerned. We have held talks and conducted patrols with people of all communities. Services such as road cleaning have resumed and traffic flow is normal," Bundela told ANI here.

"People can go out to get their daily needs from the market but we are advising them not to come out in groups," he added.

Meanwhile, the death toll in the incidents of violence in North-East Delhi has risen to 34.

Delhi Police has registered 18 FIRs and 106 people have been arrested in connection with the violence.

New Delhi, Feb 4: Senior BJP leader and Defence Minister Rajnath Singh on Monday accused Delhi's ruling Aam Aadmi Party of not implementing the central government's schemes in the national capital.

Addressing an election rally in Moti Bagh, he also sought to allay fears over the Citizenship Amendment Act (CAA), assuring the gathering that the legislation will not take away anyone's citizenship.

Singh alleged that the Chief Minister Arvind Kejriwal-led Delhi government did not do anything in the last five years.

The AAP had promised to add 5,000 buses to the fleet of the Delhi Transport Corporation (DTC), but instead the number has come down by 1,000, he claimed.

The Union minister said the AAP dispensation did not implement central schemes in Delhi fearing that the popularity of the Prime Minister Narendra Modi-led government will grow among Delhiites.

Pension schemes and the Centre's flagship health insurance scheme, Ayushman Bharat Yojana, are some of those that the Kejriwal government did not allow to be implemented in Delhi.

On the anti-CAA protests, Singh said that the opposition parties have been spreading "lies" about amended citizenship law and the National Population Register (NPR).

"The CAA will not take away anyone's citizenship. The opposition parties are spreading lies about the CAA. There should be no such politics over this. Some people are trying to write the history of the country with the ink of hatred," he said.

The culture of India is such that it considers the entire world one family, he said.

Delhi goes to polls on February 8. The results will be declared on February 11.