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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of the American Medical Association, noted that the the current guidelines issued by the WHO and CDC are based on outdated models from the 1930s of how gas clouds from a cough, sneeze, or exhalation spread.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, Jun 23: Former Karnataka Chief Minister HD Kumaraswamy on Tuesday demanded that Bengaluru should be put under lockdown for 20 days to contain the spread of coronavirus, the cases of which have risen sharply recently.

 “Stop playing with people's lives. There’s no use in sealing off only some areas. If the people of Bengaluru must live, then a lockdown of at least 20 days is needed. Otherwise, Bengaluru will become another Brazil,” Kumaraswamy said in a tweet. “People’s health is more important, not economy.”

The JD(S) leader was reacting to the BJP government's decision to impose an area-wide lockdown in Chickpet, KR Market, Kalasipalyam and Chamarajpet while streets will be sealed off in VV Puram, Siddapura, Yelahanka, Vidyaranyapura and Chickpet.

Bengaluru has witnessed a huge spike in its Covid-19 tally; the city currently has at least 919 active cases. This has sparked off fears that the contagion might have reached the community.

Kumaraswamy has also demanded welfare measures for the poor. “The poor and the labourers should be given ration immediately. The state’s 50 lakh working class should get ₹5,000 each. The aid already announced by the government hasn’t reached drivers, weavers, Madiwalas and other communities,” he said, adding that mere announcements of a package won’t be enough and “it has to be implemented.”