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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of the American Medical Association, noted that the the current guidelines issued by the WHO and CDC are based on outdated models from the 1930s of how gas clouds from a cough, sneeze, or exhalation spread.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

Bengaluru, Mar 14: Amid coronavirus threat, Karnataka Chief Minister BS Yediyurappa has ordered shutting down for a week of all places/activities where people gather in large number including swimming pools, shopping malls, schools, colleges, cinema halls etc, state Health Minister B Sriramulu said.

This comes after Yediyurappa chaired an emergency meeting with ministers and senior officials on Friday to discuss the situation.

Earlier, schools in the state had announced early summer vacation for their students this academic year as a precautionary measure. Other public places have been shut down in the state amid the Covid-19 scare.

The shut down in Karnataka comes after various other state governments ordered similar steps. Uttar Pradesh, Kerala, Jammu and Kashmir etc. are some of the states where governments have ordered shut down as a precautionary measure to contain the spread of the deadly coronavirus.

The central government has also taken several steps to contain the virus, including suspension of all visas to India till April 15. Till date, India has reported two deaths and 82 confirmed cases of the deadly coronavirus.

The World Health Organisation (WHO) has declared the coronavirus outbreak a pandemic. The virus, which originated in the Chinese city of Wuhan last year has spread to more than 100 countries worldwide, infecting over 1,30,000 people.