To fight against novel coronavirus, scientists, including one of Indian-origin who studied the aerodynamics of infectious COVID-19 disease have shared steps to curb transmission during indoor activities.

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"Wear a mask, stay six feet apart, avoid large gatherings. As the world awaits a safe and effective vaccine, controlling the COVID-19 pandemic hinges on widespread compliance with these public health guidelines," said study researcher Abhishek Kumar from the University of Colorado Boulder in the US. "But as colder weather forces people to spend more time indoors, blocking disease transmission will become more challenging than ever," Kumar added.

The study, presented at the 73rd Annual Meeting of the American Physical Society's Division of Fluid Dynamics, suggests strategies for lowering risk based on a rigorous understanding of how infectious particles mix with air in confined spaces. Research early in the pandemic focused on the role played by large, fast-falling droplets produced by coughing and sneezing. However, documented super-spreader events hinted that airborne transmission of tiny particles from everyday activities may also be a dangerous route of infection.

Fifty-three of 61 singers in Washington state, for example, became infected after a 2.5-hour choir rehearsal in March. Of 67 passengers who spent two hours on a bus with a COVID-19-infected individual in Zhejiang Province, China, 24 tested positive afterward. The researchers found that when people speak or sing loudly, they produce dramatically larger numbers of micron-sized particles compared to when they use a normal voice. The particles produced during yelling, they found, greatly exceed the number produced during coughing.

In guinea pigs, they observed influenza can spread through contaminated dust particles. If the same is true for the SARS-CoV-2, the researchers said, then objects that release contaminated dust-like tissues may pose a risk. The research focused on how the virus might spread during music performance. They discussed results from experiments designed to measure aerosol emission from instrumentalists. According to the researchers, travelling to and from office buildings in passenger cars also poses an infection risk.

Kenny Breuer and his collaborators at the Brown University performed numerical simulations of how air moves through passenger car cabins to identify strategies that may reduce infection risk. If air enters and exits a room at points far away from passengers, then it may reduce the risk of transmission. In a passenger car, they said, that means strategically opening some windows and closing others.

The researchers said that staying six feet apart "offers little protection from pathogen-bearing aerosol droplets sufficiently small to be continuously mixed through an indoor space." "A better, flow-dynamics-based understanding of how infected particles move through a room may ultimately yield smarter strategies for reducing transmission," the authors wrote.