A lot of travelers have concerns about the quality of the air in the cabin on an airplane, but have no fear! Most airplanes flying today are equipped with True High-Efficiency Particle Filters (True HEPA) or High-Efficiency Particle Filters (HEPA). These systems filter the cabin air and mix it with fresh air from outside.
The HEPA filtration system, on average, refreshes cabin air 20 times per hour, compared with just 12 times per hour in an office building. According to IATA, the International Air Transport Association, “HEPA filters are effective at capturing greater than 99 percent of the airborne microbes in the air. Filtered, recirculated air provides higher cabin humidity levels and lower particulate levels than 100 percent outside air systems.”
HEPA filters catch most airborne particles, meaning their capture standard is pretty high. A HEPA filter’s complete air change is similar to the standard used in hospitals.
Airplane cabins are divided into separate ventilation and temperature sections about every seven rows of seats. This means you share air only with those in your immediate environment and not with those further away from your seat.
Your risk of catching something airborne on a plane is lower than in many other confined spaces because of the filters and air exchange system. Even though popular belief is that the cabin air is “stale” and constantly re-used for the duration of the journey. Airborne viruses, like tuberculosis and measles, and coronavirus, are transmitted by tiny droplet nuclei that can hang in the air for up to five hours. While viruses associated with the common cold and upper respiratory track infections tend to be larger in size and heavier (consequently falling to the floor rather quickly), these particles linger. Which is where your vent comes in.
By using the vent and turning it on medium or low, you create a downdraft— simultaneously blocking these particles and forcing them to the ground faster.