Monday, November 02, 2020

COVID-19 risk in airplanes, restaurants, grocery stores cannot be easily compared: Scientists

New Delhi: While a recent study has claimed that dining out, and grocery shopping could be more dangerous than air travel during the COVID-19 pandemic, partly due to special ventilation systems in aeroplanes, some scientists say such a comparison cannot be made without knowing if mask-wearing and social distancing norms are properly followed in each of these scenarios.

In the research, funded by airlines, airports and aircraft manufacturers, scientists from the Harvard T H Chan School of Public Health in the US, said the ventilation system in airplanes made of High Efficiency Particulate Air (HEPA) filters continuously circulate and refresh the air supply, "filtering out more than 99 per cent of the particles that cause COVID-19."

However, researchers including Arnold I Barnett from the Massachusetts Institute of Technology (MIT) in the US, said the HEPA filters may not function as effectively in airplanes as the report suggests.

"HEPA filters are very good, but not as effective as US airlines suggest. They are not foolproof and there are numerous examples of transmission despite these filters," Barnett, a professor of statistics with a focus on problems of health and safety, told PTI.

He noted that transmission probability depends on a contagious passenger's emissions of the virus via breathing, speaking, and coughing or sneezing -- a mixture that varies from person to person -- as well as the movement of droplets and aerosols given the geometry of the airplane and its powerful HEPA air-purification systems.

"None of the processes is fully understood for COVID-19," the MIT scientist noted Abraar Karan from the Department of Medicine at Harvard Medical School in the US, also expressed concern about transmission risk aboard airplanes.

"For those considering flying, the reality is that while planes have great ventilation systems, we don't have a good idea of how many COVID-19 cases were actually infected on the flight itself," Karan tweeted.

"We are not testing the right way to figure this out," he added.

Commenting on the risk of contracting COVID-19 in airplanes as compared to the odds in grocery stores and restaurants, Justin Yang from the Harvard T H Chan School of Public Health, who was unrelated to the study, said such an evaluation "cannot be made in a simple way."

Yang, whose team recently published a study on COVID-19 infection among grocery store workers at an outlet in the US, said "there isn't really a safer-riskier order of situations between airplanes and grocery stores as it depends on many factors."

01/11/20 PTI/India TV

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