Experts reveal strategies to reduce indoor transmission of COVID-19

As colder weather forces people to spend more time indoors, blocking COVID-19 transmission will become more challenging than ever, say scientists.

By: Jahnavi Sarma | | Published: November 24, 2020 11:55 am

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."

As the world awaits a safe and effective vaccine, controlling the COVID-19 pandemic hinges on widespread compliance with public health guidelines. Hence, 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. This research from the University of Colorado Boulder in the US says that as colder weather forces people to spend more time indoors, blocking disease transmission will become more challenging than ever. Also Read - COVID-19 Live Updates: Cases in India surge to 91,77,840 while death toll reaches 1,34,218

Usual precautions to reduce transmission

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 conducted during the early days of the pandemic focused on the role played by large, fast-falling droplets produced by coughing and sneezing. Some of the safety precautions advised are – Also Read - This existing vaccine may protect you against COVID-19

Wearing a face mask
Staying six feet apart
Avoiding large gatherings

Experts identify new route of infection

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. Also Read - 5 Myths about wearing a face mask you should stop believing

Risks of transmission in enclosed spaces

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. They 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.

Social distancing may offer little protection

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.

New safety guidelines proposed

MIT mathematicians Martin Bazant and John Bush proposed a new safety guideline built on existing models of airborne disease transmission to identify maximum levels of exposure in a variety of indoor environments. Their guideline depends on a metric called “cumulative exposure time,” which is determined by multiplying the number of people in a room by the duration of the exposure. The maximum depends on the size and ventilation rate of the room, the face covering of its occupant, the infectiousness of aerosolized particles, and other factors. To facilitate easy implementation of the guideline, the researchers worked with chemical engineer Kasim Khan to design an app and online spreadsheet that people can use to gauge the risk of transmission in a variety of settings.

(With inputs from Agencies)

Published : November 24, 2020 11:55 am

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