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How big will the changes need to be in commercial aircraft ventilation to minimize transition of the coronavirus? Transmission can be minimized by downflow ventilation in the cabin-—could this be a fast retrofit?  How would it be verified that air inside an airplane cabin is safe?

Air Transport World Editor-in-Chief Karen Walker responds: 

All modern airliners have very sophisticated cabin air systems with hospital-standard HEPA filters, so air is both cleaned and kept moving on a continuous basis. 

This is probably the single biggest factor as to why there have been some known cases of people boarding airliners for long flights and it later being discovered they were infected with COVID-19 before they boarded, but follow up tracing has seen no cases of transmission to other passengers. On one Taiwanese airline repatriation flight from New York to Taiwan, the airplane was almost full, and several people boarded even though they were already sick. There was not a single transmission to others on the flight, including the crew. So there is no need for new airliner ventilation systems, as they already have very effective systems. 

This also demonstrates—and has been backed by a number of independent studies—that cabin air is not just safe; it’s safer than in most homes, shops or restaurants. There is a very natural “separation barrier” in every airliner as well: the rows of seat backs. Passengers sit forward-facing and not face-to-face.

The airline industry appears to be reaching consensus on requiring all passengers and crew to wear face coverings onboard, throughout the flight and while in an airport. This is being regarded as a practical extra layer of hygiene safety for as long as a coronavirus vaccine is not available and rapid testing is costly and only available in a very limited number of places.