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The current physical distancing guidelines provided by the World Health Organisation (WHO) and by the US Centers for Disease Control and Prevention (CDC) may not be adequate to curb the coronavirus spread, according to a research which says the gas cloud from a cough or sneeze may help virus particles travel up to 8 metres. The research, published in the Journal of the American Medical Association, noted that the the current guidelines issued by the WHO and CDC are based on outdated models from the 1930s of how gas clouds from a cough, sneeze, or exhalation spread.

Study author, MIT associate professor Lydia Bourouiba, warned that droplets of all sizes can travel 23 to 27 feet, or 7-8 metres, carrying the pathogen.

According to Bourouiba, the current guidelines are based on "arbitrary" assumptions of droplet size, "overly simplified", and "may limit the effectiveness of the proposed interventions" against the deadly pandemic.

 She explained that the old guidelines assume droplets to be one of two categories, small or large, taking short-range semi-ballistic trajectories when a person exhales, coughs, or sneezes.

However based on more recent discoveries, the MIT scientist said, sneezes and coughs are made of a puff cloud that carries ambient air, transporting within it clusters of droplets of a wide range of sizes.

Bourouiba warned that this puff cloud, with ambient air entrapped in it, can offer the droplets moisture and warmth that can prevent it from evaporation in the outer environment.

"The locally moist and warm atmosphere within the turbulent gas cloud allows the contained droplets to evade evaporation for much longer than occurs with isolated droplets," she said.

"Under these conditions, the lifetime of a droplet could be considerably extended by a factor of up to 1000, from a fraction of a second to minutes," the researcher explained in the study.

The MIT scientist, who has researched the dynamics of coughs and sneezes for years, added that these droplets settle along the trajectory of a cough or sneeze contaminating surfaces, with their residues staying suspended in the air for hours.

"Even when maximum containment policies were enforced, the rapid international spread of COVID-19 suggests that using arbitrary droplet size cutoffs may not accurately reflect what actually occurs with respiratory emissions, possibly contributing to the ineffectiveness of some procedures used to limit the spread of respiratory disease," Bourouiba wrote in the study

Mangaluru, Jun 3: Cyclone Nisarga did not land in Karnataka and has passed its border with heavy rains and strong winds, said an official on Wednesday.

However rains continued to lash parts of coastal Karnataka. There was no report of any casualty, the official added.

"It has already passed. We have not got any reports of fatalities. A heavy rain was expected and the deputy commissioners were alerted. Fishermen too were warned," said Karnataka State Disaster Management Authority (KSDMA) Principal Secretary T K Anil Kumar.

Kumar said Nisarga's actual landing is in Maharashtra and the warning was given for that state and Gujarat.

"In the fringe proportion (of Karnataka), high winds were expected and fishermen were warned not to venture into the sea," he said.

Kumar said the department interacted with the deputy commissioners of Belagavi, Uttara Kannada, Udupi, Dakshina Kannada, Chikkamagaluru and Shivamogga and alerted them about heavy rains.

Karnataka State Natural Disaster Monitoring Centre Director Srinivas Reddy said the department has kept four National Disaster Relief Force (NDRF) teams on standby in Mangaluru and Kodagu for any eventuality.

The teams have been mobilized from Guntur in Andhra Pradesh.

"More rain is predicted in coastal districts. Wind speed too will be more in coastal areas," said Reddy.

According to a Met Department official, the track of Nisarga is expected to be 200-400km off Karnataka coast.

"Sudden wind speed had been reported along the coast. We had issued port warnings," said the official.