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.
Comments
An Indian Haj subsidy that did not exist!
Thank you Prime Minister Modi for ending Haj subsidy that never existed.
I completely welcome this move making the announcement, minister Mukhtar Abbas Naqvi said: “We believe in empowerment without appeasement.”Naqvi did not elaborate what he meant by “appeasement” but for decades, Haj subsidy remained a whip in the hands of right-wing parties to attack political rivals. Bharatiya Janata Party to embarrass rivals by accusing them of “appeasing” Muslims by subsiding expenses involved in the pilgrimage to Makkah and Madina. Angered by this attack, several Muslims have been demanding an end to the subsidy.
However, it is important to understand what this subsidy was and whether Muslims actually benefitted from it. In 2016-17, the government budgeted Rs 4.5 billion subsidy for around 100,000 Muslims who performed Haj last year. Each pilgrim paid around Rs 220,000 (amount varies each year) for airfare; stay in Makkah and Madina and for miscellaneous expenses. This money is paid to government-managed Haj committees which then transfers this money to other agencies. In other words, each Muslim pays for his/her own Haj expenses.
A significant chunk of money paid by Muslims goes to India’s government-owned national carrier Air India which enjoys a virtual monopoly on Haj circuit. The airline picks up passengers from around a dozen cities and flies them to Jeddah. The Air India inflates India-Jeddah tickets during the Haj season. This so-called government subsidy is used to pay for tickets that are always higher than the prevailing airfare charged by other airlines. A breakdown would show that an Air India ticket to Jeddah would cost more than a trip to Los Angeles from India. Essentially, the government takes money from one pocket and puts it back in another. Muslim have always demanded global tenders for Haj flights and for providing accommodation in Makkah and Madina..
However, while Naqvi sought to take a high moral ground by claiming that his party appeases no section of the society, his own government spends billions of rupees on organizing Hindu pilgrimages every year
Naqvi saab, this is what you learnt in Madrasa? U r Back-Stabbing Muslims. There is no 1% quality of muslim in you. After joining BJP you have lost it. First learn humanity. Almighty will give answers for all problems you have created for others.
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