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

While a recent study has claimed that dining out, and grocery shopping could be more dangerous than air travel during COVID-19 pandemic, partly due to special ventilation systems in airplanes, some scientists say such a comparison cant be me without kwing if mask-wearing and social distancing rms are properly followed in each of se scenarios.

In research, funded by airlines, airports and aircraft manufacturers, scientists from Harvard T H Chan School of Public Health in US, said ventilation system in airplanes me of High-Efficiency Particulate Air (HEPA) filters continuously circulate and refresh air supply, "filtering out more than 99 per cent of particles that cause COVID-19." However, researchers including Arld I Barnett from Massachusetts Institute of Techlogy (MIT) in US, said HEPA filters may t function as effectively in airplanes as report suggests.

"HEPA filters are very good, but t as effective as US airlines suggest. y are t foolproof and re are numerous examples of transmission despite se filters," Barnett, a professor of statistics with a focus on problems of health and safety, told PTI.

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

"ne of processes is fully understood for COVID-19," MIT scientist ted.

Abraar Karan from Department of Medicine at Harvard Medical School in US also expressed concern about transmission risk aboard airplanes.

"For those considering flying, 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 flight itself," Karan tweeted.

"We are t testing right way to figure this out," he ded.

Commenting on risk of contracting COVID-19 in airplanes as compared to odds in grocery stores and restaurants, Justin Yang from Harvard T H Chan School of Public Health, who was unrelated to study, said such an evaluation "cant be me in a simple way." Yang, whose team recently published a study on COVID-19 infection among grocery store workers at an outlet in US, said, "re isn't really a safer-riskier order of situations between airplanes and grocery stores as it depends on many factors." "It ultimately depends on distance you maintain from an infected person. closer you are to someone with virus, more chances you may be of getting infected," he told PTI.

public health researcher ded that risk in airplanes is "t as significant as people think," due to airflow patterns, enhanced cleaning, and mandatory mask-wearing.

"However, if you are sitting right next to an infected person, re is a significant chance of getting infected," Yang ded.

Barnett concurred.

He said, to compare risk scenarios, one must kw if social distancing and mask-wearing measures are enforced equately in respective settings.

According to MIT researcher, removing masks for extended periods in each of settings -- grocery stores, restaurants, and airplanes -- "attenuates benefits of mask-wearing." Based on his team's yet-to-be peer-reviewed study, he said taking off masks for consuming food offered in commercial planes, may significantly increase risk of passengers getting infected with virus.

If a person in a two-hour airplane journey removes ir mask for about 20 minutes, Barnett said, "it increases transmission risk by 33 per cent." "Masks reduce transmission risk by about two-thirds. If X is transmission risk over 20 minutes with a mask, and thus 3X without a mask, n total risk is about 6X for a two-hour flight and 8X (i.e., 5X + 3X) with a 20-minute mask break. ratio of 8X to 6X is 1.33. Of course, this is an approximation," he explained.

While mortality risk for domestic air passengers who contract COVID-19 may be below US population-wide aver, Barnett and his team said, COVID-19 infections on planes can cause deaths to some people who were t passengers.

"se indirect victims of infections incurred during flights (i.e. of tertiary infections) could well outnumber direct victims," he ted.