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of the American Medical Association, noted that the the current guidelines issued by the WHO and CDC are based on outdated models from the 1930s of how gas clouds from a cough, sneeze, or exhalation spread.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

Thiruvananthapuram, May 22: Kerala reported its highest rise of COVID-19 cases in a single day with 42 new cases on Friday of which 23 returned from other states and 17 from abroad.

Addressing media persons, Kerala Chief Minister Pinarayi Vijayan said that of the new cases, 23 have come back from other States (Maharashtra-21, Tamil Nadu-1 and Andhra Pradesh-1) and 17 have returned from abroad (Kuwait-7, UAE-5, Saudi Arabia-2 and Qatar-2). Two are cases of local transmission including one health worker in Kasargod.

"A total of 12 persons from Kannur district, seven in Kasargod district, five each from Kozhikode and Palakkad districts, four each in Thrissur and Malappuram districts, two from Kottayam district, and one each in Kollam, Pathanamthitta and Wayanad districts are those who have tested positive, " he said.

Meanwhile, two patients under treatment for Coronavirus in Malappuram district have tested negative today. The total number of confirmed Covid-19 cases in Kerala is 732 and 216 patients are now under treatment in different hospitals. Kannur and Malappuram districts have 36 patients each, followed by 26 in Palakkad district, 21 in Kasargod district, 19 in Kozhikode district and 16 in Thrissur district.

The Chief Minister said that a 73-year-old woman had died in Thrissur district. She had recently returned from Mumbai.

There are 84,258 persons under observation across the state, 83,649 are quarantined at their homes or institutional quarantine centres and 609 are isolated in hospitals.

A total of 162 persons were admitted to hospitals today.

Till now, 51,310 samples have been sent for testing and 49,535 samples have been confirmed without any infection. Apart from this, as part of sentinel surveillance of high-risk groups, 7,072 samples were tested separately and out of these, 6,630 samples have been confirmed with no infection.
No new place was declared as hotspot today and there are 28 hotspots in the state.

So far, 91,344 people have come to the state from foreign countries and other states by road, sea and air.

Expressing concern over the rising numbers, the Chief Minister said, "The increase in numbers is a serious warning. Our COVID-19 preventive measures need to be enhanced. More people are expected to come back and we will ensure proper testing, treatment and care to all. Serious patients are among those who are coming back."
"We will ensure additional facilities including ventilators in hospitals to accommodate more in-patients. Huge rush is being seen at some places. People should observe more self-restraint or else all efforts will become ineffective," he added.