DK Shivakumar or MB Patil likely to become Karnataka Congress chief

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of the American Medical Association, noted that the the current guidelines issued by the WHO and CDC are based on outdated models from the 1930s of how gas clouds from a cough, sneeze, or exhalation spread.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 8: Facing a shortage of labour, some top builders in the city have initiated efforts to bring back the migrant workers, who have returned to their native places following the COVID-19 lockdown, and are holding parleys with Railway authorities for operation of special trains to ferry them.

After the lockdown was announced, many construction projects came to a halt and accordingly the labourers were rendered jobless. These migrant workers preferred to go back to their home state as they were not paid when the projects were stopped and were caught in the big financial mess. Many of these migrants even chose to cover thousands of kilometres by foot when even trains, buses or any motor vehicles were not operating.

Keeping their woes in view, the Centre decided to run the Shramik Special trains to ferry them to their native places. But, after they were gone, the builders found themselves in a lurch. An executive of a builder told PTI "Yes, our builder and a few others are in talks with the Railways to run the special train to bring back the labourers." She said nothing has been materialised as of now.

According to her, the builders took the contact numbers of the workers when they left the city to their home states and are now contacting them one by one. The South Western Railway has so far sent 3.11 lakh migrant workers in 216 Shramik Special trains starting from May 3 to June 6.