141 feared buried in landslide in Sichuan's Maoxian

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.

Karachi, May 23: Ninety-seven people were killed and two survived when a passenger plane crashed into homes in Pakistan's southern city of Karachi, health officials said Saturday.

The Pakistan International Airlines (PIA) plane had made multiple approaches to land at the city's airport when it came down in a residential area, damaging buildings and sparking a rescue operation that lasted into the night.

All passengers and crew had been accounted for and the bodies of those killed had been recovered from the crash site, the Sindh Health Ministry said, adding that 19 had been identified.

A local hospital earlier reported it had received the bodies of people killed on the ground.

The site remained cordoned off on Saturday morning.

The crash sent plumes of smoke were into the air as rescue workers and residents searched the debris for people and as firefighters tried to extinguish the flames.

An AFP reporter witnessed charred bodies being loaded into ambulances.

PIA said the plane lost contact with air traffic control just after 2:30 pm (0930 GMT) travelling from Lahore to Karachi.

The disaster comes as Pakistanis prepare to celebrate the end of Ramadan and the beginning of Eid al-Fitr, with many travelling back to their homes in cities and villages.

Beijing, Jul 6: A city in northern China on Sunday sounded an alert after a suspected case of bubonic plague was reported, according to official media here.

Bayannur, Inner Mongolia Autonomous Region, announced a level III warning of plague prevention and control, state-run People’s Daily Online reported.

The suspected bubonic plague case was reported on Saturday by a hospital in Bayannur. The local health authority announced that the warning period will continue until the end of 2020.

"At present, there is a risk of a human plague epidemic spreading in this city. The public should improve its self-protection awareness and ability, and report abnormal health conditions promptly,” the local health authority said.

On July 1, state-run Xinhua news agency said that two suspected cases of bubonic plague reported in Khovd province in western Mongolia have been confirmed by lab test results.

The confirmed cases are a 27-year-old resident and his 17-year-old brother, who are being treated at two separate hospitals in their province, it quoted a health official as saying.

The brothers ate marmot meat, the health official said, warning people not to eat marmot meat.

A total of 146 people who had contact with them have been isolated and treated at local hospitals, according to Narangerel.

Bubonic plague is a bacterial disease that is spread by fleas living on wild rodents such as marmots. It can kill an adult in less than 24 hours if not treated in time, according to the World Health Organization (WHO).

A couple died of bubonic plague in the western Mongolian province of Bayan-Ulgii last year after eating raw marmot meat.

The news of bubonic plague came after Chinese researchers issued an early warning over another potential pandemic caused by an influenza virus in pigs.

Scientists from China Agricultural University, the Chinese Centre for Disease Control and Prevention and other institutes detected a pig influenza virus bearing genotype 4 (G4), which is contagious among pigs and has the possibility of jumping to humans, as the G4 virus is able to bind with human cells, state-run Global Times reported last week.

The researchers are concerned that it could mutate further so that it can spread easily from person to person, and trigger a global outbreak, BBC reported.

"Controlling the prevailing G4 EA H1N1 viruses in pigs and close monitoring in human populations, especially workers in the swine industry, should be urgently implemented," Chinese researchers warned in the paper.

The new diseases were reported even as China grappled with the second attack of Covid-19 in Beijing after controlling it in Wuhan where it was first reported in December last year.

On Saturday, Beijing reported a single-digit Covid-19, local authorities said Sunday.

The number of newly confirmed Covid-19 cases reached a peak in Beijing on June 13 and 14 and then started declining in general, Xinhua quoted local officials as saying.

From June 11 to July 4, the city reported 334 confirmed locally transmitted cases, 47 per cent of whom are workers of the Xinfadi wholesale food market, the official said.