Action will be taken against Swiss deposits, promises Finance Minister

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.

New Delhi, Apr 9: Kerala opposition coalition United Democratic Front on Thursday submitted a roadmap to Prime Minister Narendra Modi for staggered lifting of ongoing lockdown due to COVID-19 pandemic.

The coalition led by leader of opposition Ramesh Chennithala has given a set of recommendations to Modi in this regard, which include those made by an expert committee headed by deputy leader of opposition M K Muneer.

The committee was set up to suggest measures to be taken by the government for smooth transition from lockdown to normalcy.

It listed an eight-point exit strategy for removing lockdown in a staggered approach at a district level, with emphasis on hotspots to avoid further spread of virus and ensure smooth restart of economy.

This approach is tuned to the unique needs of each district and all the districts should also be categorised as per their risk levels, the report said.

The report has also been submitted to chief ministers of all states, former prime minister Manmohan Singh, Congress president Sonia Gandhi, senior Congress leader Rahul Gandhi among others.

The committee recommended that COVID-19 rapid testing must be enhanced across the country and the testing target be widened to 500 tests per one lakh population.

"A step-by-step approach is necessary for each sector along with conditions that need to be considered for each sector," the report said.

"There is a need for a comprehensive economic stimulus package in addition to the ones already announced after considering all the industries," it added.