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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, Jul 10: Former Karnataka Chief Minister and Congress leader Siddaramaiah on Thursday condemned the decision of the HRD Ministry to drop chapters on citizenship, secularism and federalism from Class 11 political science syllabus, stating that this will "deprive a generation of students from understanding the important pillars of Indian democracy".

"I strongly condemn the decision of @HRDMinistry to drop chapters on citizenship, secularism and federalism. This will deprive a generation of students from understanding the important pillars of Indian democracy. #Stop Saffronisation Of Education," Siddaramaiah tweeted.

The Congress leader further alleged that BJP does not believe in the principles of citizenship, secularism and federalism.

"Chapters on citizenship, secularism and federalism are dropped from Class 11 Pol Science. syllabus. Does this explain something? Yes, it explains that @BJP4India doesn't believe in these principles and validates its past behaviour," he said in another tweet.

Earlier in the day, Union Human Resource Development (HRD) Minister Ramesh Pokhriyal Nishank rejected criticism over alleged conspiracy in CBSE's decision to reduce the syllabus of schools due to COVID-19 outbreak and urged the critics to "leave politics out of education".

"There has been a lot of uninformed commentary on the exclusion of some topics from #CBSESyllabus. The problem with these comments is that they resort to sensationalism by connecting topics selectively to portray a false narrative," the Union Minister tweeted.

"It is our humble request:#Education is our sacred duty towards our children. Let us leave politics out of education and make our politics more educated," he added.

The CBSE has revised the syllabus for the classes IX to XII during the academic session 2020-21 in the wake of the situation created by COVID-19.

In a circular issued to all the heads of the institutions affiliated to it, the CBSE had said that the revision of syllabi has been done due to the extraordinary situation prevailing in the country and different parts of the world.