MIAMI – American Airlines (AA) recently announced it will install High-Efficiency Particulate (HEPA) filters on its smaller regional jets. Up until now, the carrier has had filters installed across all of its mainline fleet, including the Airbus A320 and Boeing 737. In addition, American will now have the HEPA filters installed on its Embraer E-135 and E-145 aircraft.

Since the onset of the COVID-19 pandemic, air travel has slowed, not only due to travel restrictions but also concerns over safety. Much focus has been placed on aircraft cleanliness, both on the cleaning of surfaces but also the maintaining of air quality during flight. Many tests have already been designed specifically to isolate the impact of airborne particle transmission among passengers in aircraft cabins.

Earlier this week, the Washington Post reported that the Department of Defense (DoT) participated in one such study, which found that contracting a lethal does of the COVID-19 virus mid-flight as a passenger is not as likely as originally thought. In the test, mannequins, some masked and unmasked, were placed aboard Boeing 777 and 767 aircraft.

American Eagle. Photo: Nicholas Vitolano

The Study

Researchers then released particles in the air mimicking those of the COVID-19 virus. After all the tests were completed, the findings suggested that the transmission rates of the virus in flight are much lower than expected. To be more specific, a passenger would have to be sitting next to an infected person for at least 54 hours before being able to contract a lethal dose of the virus.

Even with this result, however, researchers also were quick to point out the continued importance of face coverings and proper air cabin filtration.

First Class aboard the American Airlines Boeing 767-200. (Credits: Chris Sloan)

How Effective Are the Filters?

American Airlines has said that the HEPA filters being used on its flights capture 99.97% of airborne microbes, and that cabin air is regularly circulated every 2 to 4 minutes.

In addition to the filtering and circulation, outside air is added to the mix by way of the engine compressor on the exterior of the aircraft, ensuring that fresh air is added consistently throughout the flight. The filters have been used by AA jets since the late 1990s.

Featured image: Shon Fridman (@sierrafoxtrot.aviation). Source: Gary Leff from