How much of the air in an airplane is recirculated?

In modern aircraft cabin, close to half of the cabin air is recircualted. As this IATA briefing paper on Cabin air quality – risk of contagious viruses notes: The cabin air system is designed to operate most efficiently by delivering approximately 50 percent outside air and 50 percent filtered, recirculated air.

How is the recycled air in a plane?

Some of this is diverted for the passengers to breathe. Because the compression heats up the air, it must first be ducted around the wings to be cooled down. The air already in the cabin is passed through high-efficiency particulate (HEPA) filters to remove bacteria and viruses and then mixed 50:50 with the fresh air from outside.

What’s the balance between fresh air and recirculated air?

Case in point: the following is from a 2009 issue of The Economist: “Typically an airline will strike a balance by using a 50:50 mixture of fresh and recirculated air,” says the magazine. “Although pilots can reduce the amount of fresh air to save fuel. Some are thought to cut it back to only 20 percent.” My mouth dropped open when I read this.

How is the air in an airplane clean?

In reality, the air is very clean. On all modern aircraft, passengers and crew breathe a mixture of fresh and recirculated air. Using this combination rather than fresh air only makes it easier to regulate temperature and helps maintain a bit of humidity (more on the humidity in a moment).

In modern aircraft cabin, close to half of the cabin air is recircualted. As this IATA briefing paper on Cabin air quality – risk of contagious viruses notes: The cabin air system is designed to operate most efficiently by delivering approximately 50 percent outside air and 50 percent filtered, recirculated air.

Some of this is diverted for the passengers to breathe. Because the compression heats up the air, it must first be ducted around the wings to be cooled down. The air already in the cabin is passed through high-efficiency particulate (HEPA) filters to remove bacteria and viruses and then mixed 50:50 with the fresh air from outside.

Case in point: the following is from a 2009 issue of The Economist: “Typically an airline will strike a balance by using a 50:50 mixture of fresh and recirculated air,” says the magazine. “Although pilots can reduce the amount of fresh air to save fuel. Some are thought to cut it back to only 20 percent.” My mouth dropped open when I read this.

In reality, the air is very clean. On all modern aircraft, passengers and crew breathe a mixture of fresh and recirculated air. Using this combination rather than fresh air only makes it easier to regulate temperature and helps maintain a bit of humidity (more on the humidity in a moment).