A new study released by the U.S. Department of Defense (DOD) on Thursday found that the risk of contracting an airborne virus like COVID-19 on an airplane is “extremely unlikely” if passengers wear masks.

After carrying out experiments on board the Boeing 777-200 and 767-300, researchers concluded that the low risk of transmission is due to the aircrafts’ high efficiency particulate air (HEPA) filtration systems and the high air-exchange rate, which is “not matched by other indoor venues, including most hospital and biosafety-level 3 laboratories.”

Noteworthy in the study is the fact that it does not matter where passengers sit or how crowded the plane is—as long as masks are worn, the risk of transmission remains low.

"All areas on both aircraft proved to be extremely effective in dispersing and filtering out the aerosol particles," said Navy Lt. Cmdr. Joseph Pope, USTRANSCOM Operations directorate liaison for the airflow particle test. "So specifically, can I tell you to sit in seat XYZ? No, they all performed very well."

The study did find more time spent in the airplane elevates the risk of infection, but only after extremely long periods of time: passengers traveling on board a Boeing 777 would need to spend at least “54 hours sitting next to an index patient in the economy section” to be exposed to an infectious dose of particles.

It is important to note that the study focused only on aerosol transmission, not ballistic droplets—the particles that are emitted when one coughs or sneezes. Because of the risk of ballistic droplet transmission, Pope said that wearing a mask is crucial as it can be highly effective in catching those particles.

The data collected in this study will be used to develop strategies around cabin loading and seating configuration and will “eventually inform the DOD on contact tracing requirements needed for specific aircraft.”

Further, we are pleased by the DOD’s unequivocal embrace of wearing masks. U.S. Travel has long advocated for an adherence to healthy travel practices, which include wearing masks, frequent hand washing and staying home if feeling sick. We recently updated our Travel Confidently toolkit, which includes a suite of resources centered around the theme of a healthy and safe travel experience being a shared responsibility.

U.S. Travel is encouraged by the DOD’s findings that COVID-19 transmission aboard planes is extremely unlikely. The availability of scientific data is hugely beneficial in restoring consumers’ confidence in the ability to fly safely.