Over 100 'chimneys' drilled to reach trapped Thai boys

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.

Geneva, Mar 12: For the global economy, virus repercussions were profound, with increasing concerns of wealth- and job-wrecking recessions. U.S. stocks wiped out more than all the gains from a huge rally a day earlier as Wall Street continued to reel.

The Dow Jones Industrial Average dropped 1,464 points, bringing it 20% below its record set last month and putting it in what Wall Street calls a “bear market.” The broader S&P 500 is just 1 percentage point away from falling into bear territory and bringing to an end one of the greatest runs in Wall Street’s history.

WHO officials said they thought long and hard about labeling the crisis a pandemic — defined as sustained outbreaks in multiple regions of the world.

The risk of employing the term, Ryan said, is “if people use it as an excuse to give up.” But the benefit is “potentially of galvanizing the world to fight.”

Underscoring the mounting challenge: soaring numbers in the U.S. and Europe’s status as the new epicenter of the pandemic. While Italy exceeds 12,000 cases and the United States has topped 1,300, China reported a record low of just 15 new cases Thursday and three-fourths of its infected patients have recovered.

China’s totals of 80,793 cases and 3,169 deaths are a shrinking portion of the world’s more than 126,000 infections and 4,600 deaths.

“If you want to be blunt, Europe is the new China,” said Robert Redfield, the head of the U.S. Centers for Disease Control and Prevention.

With 12,462 cases and 827 deaths, Italy said all shops and businesses except pharmacies and grocery stores would be closed beginning Thursday and designated billions in financial relief to cushion economic shocks in its latest efforts to adjust to the fast-evolving crisis that silenced the usually bustling heart of the Catholic faith, St. Peter’s Square.

Beijing, Jan 23: China is putting on lockdown a city of 11 million people considered the epicenter of the new coronavirus outbreak that has killed 17 and infected nearly 600 people, as health authorities around the world work to prevent a global pandemic.

The previously unknown coronavirus strain is believed to have emerged late last year from illegally traded wildlife at an animal market in the central Chinese city of Wuhan. Cases have been detected as far away as the United States, stoking fears the virus is already spreading worldwide.

Wuhan's local government said it would shut down all urban transport networks and suspend outgoing flights from the city as of 10 a.m. (0200 GMT) Thursday, state media reported, adding that the government is urging citizens to not leave the city in the absence of special circumstances.

Contrasting with its secrecy over the 2002-03 Severe Acute Respiratory Syndrome (SARS), which killed nearly 800 people, China's communist government has this time given regular updates to try to avoid panic as millions of people travel for the Chinese Lunar New Year holiday.

Chinese authorities have confirmed 571 cases and 17 deaths as of end-Wednesday, state television reported on Thursday. There are eight other known cases around the world - Thailand has confirmed four cases, while the United States, Taiwan, South Korea and Japan have each reported one.

Vice Premier Sun Chunlan said during a visit to Wuhan that authorities needed to be open about the spread of the virus and their efforts to contain it, the official Xinhua news agency reported on Thursday, comments likely to reassure global health experts.

After a meeting at its Geneva headquarters on Wednesday, the World Health Organization (WHO) said it would decide on Thursday whether to declare the outbreak a global health emergency, which would step up the international response.

If it does so, it will be the sixth international public health emergency to be declared in the last decade.

WHO Director-General Tedros Adhanom Ghebreyesus told reporters in Geneva that China's actions so far were "very strong" but called in Beijing to take "more and significant measures to limit or minimise the international spread".

"We stressed to them that by having a strong action not only they will control the outbreak in their country but they will also minimise the chances of this outbreak spreading internationally. So they recognise that," he said.

A senior U.S. State Department official also called on China to "play a bigger role in global health so they taking more and significant measures to limit or minimise the international spread".

"The lack of transparency in the past, especially with SARS ... gives us concern that that may be the case here," the official said, adding however that there were "positive signs that they have taken action in Wuhan".

Fears of a pandemic initially spooked markets but they regained their footing on Wednesday, with investors citing the robust response from authorities as reassuring.

VIRUS SPREADING

The outbreak began in Wuhan, a major transportation hub as well as central China's main industrial and commercial centre, and has now spread to other major population centers including Beijing, Shanghai and Hong Kong.

There is no known cure for the virus. Symptoms include fever, difficulty in breathing and cough, similar to many other respiratory illnesses, and can cause pneumonia.

Chinese authorities are still investigating the origins of the virus, though they confirmed the outbreak began at a market in Wuhan with illegal wildlife transactions and that it can spread from one person to another via respiratory transmission. Among confirmed patients are 15 medical workers, further adding to worries about a possible global pandemic.

Many Chinese were canceling trips, buying face masks, avoiding public places such as cinemas and shopping centers, and even turning to an online plague simulation game as a way to cope.

Airports globally stepped up screening passengers from China and the European Centre for Disease Control and Prevention (ECDC) said in a risk assessment that further global spread of the virus was likely.

Britain joined other countries including Australia in advising citizens against all but essential travel to Wuhan.