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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.

New Delhi, Jun 7: India registered its highest single-day spike of COVID-19 cases for the fifth consecutive day on Sunday, with 9,971 new infections taking the country's tally to 2,46,628, while the death toll rose to 6,929, according to the Union Health Ministry.

India registered 287 deaths in the 24 hours since Saturday morning.

India had raced past Spain on Saturday to become the fifth worst-hit nation by the COVID-19 pandemic. Now, only the US, Brazil, Russia and the UK are ahead of it.

The number of active COVID-19 cases stands at 1,20,406, according to the Health Ministry.

A total of 1,19,292 people have recovered and one patient has migrated, the Ministry said.

During the last 24 hours, a total of 5,220 COVID-19 patients have been cured, the ministry said.

"Thus, around 48.37 per cent patients have recovered so far," a senior ministry official said.

The tally of confirmed cases includes foreigners.

The Indian Council of Medical Research has further ramped up the testing capacity for detecting the novel coronavirus in infected persons.

The number of government labs has been increased to 531 and private labs to 228, taking the total number of labs to 759.

As many as 1,42,069 samples were tested in the last 24 hours, taking the total number of samples tested till now to 46,66,386.

Deaths in India per lakh population (0.49) are much lower than the world average of 5.17 and are the lowest among countries that have eased lockdown such as Germany (10.35), Italy (55.78), the UK (59.62) and Spain (58.06), as per a WHO situation report cited by the Health Ministry.

Cases in India per lakh population (17.32) are much lower than the world average of 87.74 and are the lowest among countries that have eased lockdown such as Germany (219.93), Italy (387.33), the UK (419.54) and Spain (515.61).

Of the 287 deaths reported since Saturday morning, 120 were from Maharashtra, 53 from Delhi, 29 from Gujarat, 19 from Tamil Nadu, 17 from West Bengal, 15 from Madhya Pradesh, 13 from Rajasthan, 10 from Telangana, three from Jammu and Kashmir, two each from Karnataka, Punjab and Chhattisgarh and one each from Kerala and Bihar.

Of the total 6,929 fatalities, Maharashtra tops the tally with 2,969 deaths, followed by Gujarat with 1,219 deaths, Delhi with 761, Madhya Pradesh with 399, West Bengal with 383, Uttar Pradesh with 257, Tamil Nadu with 251, Rajasthan with 231, Telangana with 123 and Andhra Pradesh with 73 deaths.

The death toll reached 59 in Karnataka and 50 in Punjab.

Jammu and Kashmir has reported 39 fatalities due to the disease, Bihar has 30, Haryana has 24 deaths, Kerala has 15, Uttarakhand has 11, Odisha has eight and Jharkhand has reported seven deaths so far.

Himachal Pradesh and Chandigarh have registered five COVID-19 fatalities each. Assam and Chhattisgarh have recorded four deaths each.

Meghalaya and Ladakh have reported one COVID-19 fatality each, according to the Health Ministry data.

According to the Ministry's website, more than 70 per cent of the deaths are due to comorbidities.

The highest number of confirmed cases in the country are from Maharashtra at 82,968, followed by Tamil Nadu at 30,152, Delhi at 27,654, Gujarat at 19,592, Rajasthan at 10,331, Uttar Pradesh at 9,733 and Madhya Pradesh at 9,228, according to the Health Ministry data updated in the morning.

The number of COVID-19 cases has gone up to 7,738 in West Bengal, 5,213 in Karnataka, 4,915 in Bihar and 4,510 in Andhra Pradesh.

It has risen to 3,952 in Haryana, 3,496 in Telangana, 3,467 in Jammu and Kashmir and 2,781 in Odisha.

Punjab has reported 2,515 coronavirus infections so far, while Assam has 2,397 cases. A total of 1,807 people have been infected with the virus in Kerala and 1,303 in Uttarakhand.

Jharkhand has registered 1,000 cases, Chhattisgarh has 923, Tripura has 747, Himachal Pradesh has 400, Chandigarh has 309 cases, Goa has 267, Manipur has 157, Nagaland has 107, and Puducherry and Ladakh have 99 cases.

Arunachal Pradesh has 47 COVID-19 cases, while Andaman and Nicobar Islands and Meghalaya have registered 33 infections each.

Mizoram has reported 24 cases and Dadar and Nagar Haveli has 19 cases, while Sikkim has reported seven cases till now.

"8,605 cases are being reassigned to states," the Ministry said on its website adding, "our figures are being reconciled with the ICMR."

State-wise distribution is subject to further verification and reconciliation, it added.

Washington, May 27: Most viruses and other germs do not spread easily on flights, the US Center for Disease Control and Prevention has said in its COVID-19 guidelines which do not recommend following social distancing between two passengers inside a plane or keeping the middle seat unoccupied.

As a result of coronavirus pandemic, air traffic inside the US has come to a near halt. Air traffic is said to be down to about 90 per cent. For all travellers coming from overseas, the Center for Disease Control and Prevention (CDC) has recommended 14 days quarantine.

"Most viruses and other germs do not spread easily on flights because of how air circulates and is filtered on aeroplanes," the CDC has said in its set of COVID-19 guidelines for air travellers.

However, it noted that the air travellers were not risk-free especially in the time of the coronavirus pandemic and recommended Americans to avoid travel as far as possible.

"Air travel requires spending time in security lines and airport terminals, which can bring you in close contact with other people and frequently touched surfaces," it said.

"Social distancing is difficult on crowded flights, and you may have to sit near others (within six feet), sometimes for hours. This may increase your risk for exposure to the virus that causes COVID-19," the CDC said.

But instead of recommended social distancing inside commercial planes, the CDC has advised a series of preventive and hygienic measures to be taken by the airlines pilot and crew to prevent the spread of coronavirus.

The US Department of Transportation and Federal Aviation Administration in its latest safety alerts for operators on May 11 said that air carriers and crews conducting flight operations having a nexus to the US, including both domestic and foreign air carriers, should follow CDC's occupational health and safety guidance.

The CDC issued its guidelines in first guidelines for the airlines and airline crew on March and again in May.

The CDC, which has issued an exhaustive social guideline measures in various sections, is silent on keeping the middle seat of a plane unoccupied so as to maintain the six feet distance between two passengers.

It calls for the plane crew to report to the CDC a traveller with specific COVID-19 symptoms like fever, persistent cough, difficulty in breathing and appearing unwell.

Asking the airlines and cabin crew to review infection control guidelines for cabin crew, the CDC recommends several measures for cabin crew to protect themselves and others, manage a sick traveller, clean contaminated areas, and take actions after a flight.

Prominent among them include washing hands often with soap and water for at least 20 seconds, particularly after assisting sick travellers or touching potentially contaminated body fluids or surfaces and use of alcohol-based hand sanitizer (containing at least 60 per cent alcohol) if soap and water are not available.

Airlines should consider providing alcohol-based hand sanitizer to cabin and flight crews for their personal use, it said.

The CDC guidelines do not recommend following social distancing inside a plane between two passengers or keeping the middle seat unoccupied. But it asks to minimise contact between passengers and cabin crew and the sick person.

"If possible, separate the sick person from others (by a distance of 2 meters or 6 feet, ideally) and designate one crew member to serve the sick person. Offer a facemask, if available and if the sick person can tolerate it. If a facemask is not available or cannot be tolerated, ask the sick person to cover their mouth and nose with tissues when coughing or sneezing," said the CDC guidelines.

If no symptomatic passengers were identified during or immediately after the flight, the CDC recommends airlines to follow routine operating procedures for cleaning aircraft, managing solid waste, and wearing PPE.

"If symptomatic passengers are identified during or immediately after the flight, routine cleaning procedures should be followed, and enhanced cleaning procedures should also be used," it said.

Clean porous (soft) surfaces (e.g, cloth seats, cloth seat belts) at the seat of the symptomatic passengers and within 6 feet of the symptomatic passengers in all directions, it added.