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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.

Thiruvananthapuram, May 25: About 100 people, including a Magistrate and some police personnel, have been asked to go into quarantine after an accused, who was produced before a lower court here following his arrest, later testedpositive, officials said on Monday. The accused, who was arrested along with two others in connection with a case relating to illicit liquor transportation two days ago, had been shifted to thePoojapura central jail after he was remanded to judicial custody.

With his sample testing positive on Sunday, theman has been sent to a designated COVID-19 hospital. The Nedumangad court magistrate, before whom he was produced, 34 police personnel, including a circle inspector, who were on duty at the Venjaramoodu police station when the accused was broughtafter his arrest, some employees of a government hospital where his swab sample was taken and 12 officials of thePoojapura central jail have gone into quarantine, police sources said.

. Meanwhile, Malayalam film actor Suraj Venjaramoodu and Vamanapuram MLA D K Murali (CPI) are under self-imposed quarantineas they had attended a function in which the circle inspector had taken part.

Two days ago, a car in which illicit liqour was being transported had hit a policeman and sped away, but people managed to stop the vehicle and the three accused, who were in an inebriated state, were arrested, sources said.

The Ministry of Health and Family Welfare has prepared a draft for guidelines for home quarantine, as well as for the use of masks by public, in view of coronavirus.

What to do in Home Quarantine?

The government says, for those taking refuge to home quarantine should stay in a well-ventilated single-room preferably with an attached or separate toilet. It adds that if another family member needs to stay in the same room, it's advisable to maintain a distance of at least 1 metre between the two.

The government advised, coronavirus patients to stay away from elderly people, pregnant women, children and persons with co-morbidities within the household as their immune system may be low. The health minister also suggested to restrict the patient's movement within the house. "Under no circumstances attend any social/religious gathering e.g. wedding, condolences, etc, said the guideline.

It also instructed the corona virus infected person to avoid sharing household items like dishes, drinking glasses, cups, eating utensils, towels, bedding, or other items with others at home. The guideline also demanded that even though home quarantine, the patient should wear a surgical mask at all times. "The mask should be changed every 6-8 hours and disposed off. Disposable masks are never to be reused, it added.

"Masks used by patients/ caregivers/ close contacts during home care should be disinfected using ordinary bleach solution (5 per cent) or sodium hypochlorite solution (1%) and then disposed of either by burning or deep burial," instructs the government.

Even for family members of a patient, the health ministry clearly instructs to use disposable gloves when cleaning the surfaces or handling soiled linen. No visitors, under any circumstances will be allowed, said the guideline.

"In case the person being quarantined becomes symptomatic, all his close contacts will be home quarantined (for 14 days) and followed up for an additional 14 days or till the report of such case turns out negative on lab testing," states the draft.

How to wear & dump masks?

There is a specific and elaborate do's and don'ts also released by the ministry. For those unsure in which mask to choose, it says, "Medical masks of different sizes and shapes are available in the market. The common ones are flat pleated masks of woven fabric which covers the nose and mouth and affixed behind the head with straps/ elastic fasteners. There are also conical or duck bill shaped masks with valves (or without valves) that fit in the contour of face over the nose and mouth, but are costlier."

However, the ministry warns, medical masks should not be used by healthy persons who are not having any symptoms "because it creates a false sense of security". Instead, it suggests to refrain from touching face, mouth, nose and eyes as well as washing hands regularly with soap for 20 seconds each time.

However, when a person develops a cough or fever, the suspected patient needs to switch to medical masks. "Use of medical three layer masks when ill, will prevent your infection from spreading to others. However you also need to wash your hands frequently to avoid spreading infection to others," read the guideline.

Even if one is not tested positive but showing symptoms, they are advised to wear masks while visiting a healthcare facility. "Close family contacts of such suspect/confirmed cases undergoing home care should also use Triple layer medical mask," it warns.

The ministry has also given point by point guideline on how to use a mask like to make sure that they are facing down while unfolding or for that matter to ensure there are no gaps on either side of the mask.

It even warns, "Fit flexible nose piece (a metallic strip that can easily be located) over nose-bridge" to ensure no one else are infected. The government also warns against simple dumping of the masks once used. Instead one should disinfect "using ordinary bleach solution (5 per cent) or sodium hypochlorite solution (1 per cent) and then disposed of either by burning or deep burial," says the Health Ministry.

COVID-19 emerged in early December 2019 in China's Wuhan province and has now spread to over 100 countries. As on March 9, 2020, India has reported 42 cases mostly among those who had travelled from affected countries.

However the government says, "It causes a minor illness in majority of patients with symptoms of fever and or cough. A small proportion of such persons may progress to severe disease with difficulty in breathing."