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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, May 19: The number of coronavirus cases crossed the one lakh mark in the country on Tuesday, while the death toll due to the infection touched 3,163, according to the Union Health Ministry.

A total of 134 deaths and 4,970 COVID-19 cases were reported in the country in the past 24 hours since 8 pm on Monday, it said.

The total number of coronavirus cases has risen to 1,01,139, the ministry said.

The number of active COVID-19 cases stood at 58,802 while 39,173 people have recovered and one patient has migrated, it said.

"Thus, around 38.73 per cent patients have recovered so far," a senior health ministry official said.

The total confirmed cases include foreigners.

Of the 134 deaths reported since Monday morning, 51 were in Maharashtra, 35 in Gujarat, 14 in Uttar Pradesh, eight in Delhi, seven in Rajasthan, six in West Bengal, four in Madhya Pradesh, three in Tamil Nadu, two each in Punjab and Jammu and Kashmir, and one each in Bihar and Telangana.

Of the 3,163 fatalities, Maharashtra tops tally with 1,249 deaths. Gujarat comes second with 694 deaths, followed by Madhya Pradesh at 252, West Bengal at 244, Delhi at 168, Rajasthan at 138, Uttar Pradesh at 118, Tamil Nadu at 81 and Andhra Pradesh at 50.

The death toll reached 37 each in Karnataka and Punjab and 35 in Telangana.

Jammu and Kashmir has reported 15 fatalities due to the disease, Haryana has 14 deaths while Bihar has registered nine and Kerala and Odisha each have reported four deaths.

Jharkhand, Chandigarh and Himachal Pradesh each have recorded three COVID-19 fatalities, while Assam has reported two deaths.

 Meghalaya, Uttarakhand and Puducherry have reported one fatality each, according to the data provided by the ministry.

According to the ministry's website, more than 70 per cent of the deaths are due to comorbidities, the existence of multiple disorders in the same person.

According to the health ministry's data updated in the morning, the highest number of confirmed cases in the country are from Maharashtra at 35,058, followed by Tamil Nadu at 11,760, Gujarat at 11,745, Delhi at 10,054, Rajasthan at 5,507, Madhya Pradesh at 5,236 and Uttar Pradesh at 4,605.

The number of COVID-19 cases has gone up to 2,825 in West Bengal, 2,474 in Andhra Pradesh and 1,980 in Punjab.

It has risen to 1,597 in Telangana, 1,391 in Bihar, 1,289 in Jammu and Kashmir, 1,246 in Karnataka and 928 in Haryana.

Odisha has reported 876 coronavirus infection cases so far, while Kerala has 630 cases. A total of 223 people have been infected with the virus in Jharkhand and 196 in Chandigarh.

Tripura has reported 167 cases, Assam has 107, Uttarakhand and Chhattisgarh have 93 cases each, Himachal Pradesh has 90 and Ladakh has registered 43 cases so far.

Goa has reported 38 COVID-19 cases, while the Andaman and Nicobar Islands has registered 33 infections.

Puducherry has registered 18 cases, Meghalaya has 13 and Manipur has seven cases. Mizoram, Arunachal Pradesh and Dadar and Nagar Haveli have reported a case each till how.

"814 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 said.