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Everything You Need to Know About Airplane Ventilation

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Oxygen is scarce above 10,000 feet, yet we take for granted that as the plane slices through the stratosphere at 35,000 feet, we’re on the inside, breathing easy. That’s all thanks to cabin pressurization, first introduced in 1939 with the Boeing Stratoliner. This invention revolutionized air travel, allowing aircraft to fly higher in low–friction atmosphere while maintaining cabin air pressure and oxygen levels equivalent to those at 8,000 feet.

Modern aircraft are equipped with ventilation systems so efficient you hardly notice they are there. Air flows constantly into the cabin via ceiling ducts and back out through vents near the floor. It is refreshed every few minutes, more often than in your home or office.

Science of Travel
By Ari Magnusson
Illustration by Amrita Marino
July 1, 2020
An illustrated gif of a woman on an airplane blowing air

The cabins of Air Canada’s mainline fleet use a mix of outside air – drawn in and compressed to maintain cabin pressure – and purified cabin air that passes through high–efficiency particulate air (or HEPA) filters. This fresh–filtered combo makes it easier to regulate cabin temperature, maintain some humidity and ensure that the total air supply is sterile and particle–free. In fact, it is cleaner than in many other indoor spaces.

So, that little nozzle above your head: It’s a breath of fresh air.
 

Air Quotes

  • The extremely close–knit fibres in HEPA filters remove at least 99.9 percent of particles, including microscopic viruses and bacteria. The filters on all Air Canada mainline aircraft are similar to those in operating rooms and high–tech factories.

  • Multiple studies, including one by the European Union Aviation Safety Agency in 2017, found that air quality in aircraft cabins is similar or better than what is observed in normal indoor environments on the ground.

  • Before the advent of pressurized cabins, flight attendants were registered nurses who could care for passengers made sick by turbulence or the effects of altitude.