Where do aerotoxic fumes come from?   

 

Due to the thinness of the air at altitude, jet aeroplanes need a constant supply of compressed air in the cabin to sustain life.

 

The engines also need compressed air for efficient combustion of the fuel, and this is also used to provide pressurized air for the aircraft cabin. Since1962 this has been provided directly from the engines ahead of the combustion chamber and piped via the air conditioning system directly into the cabin. This compressed air is known as, "Bleed Air" because it is ‘bled’ from the engine systems.

 

 However, this bleed air is unfiltered and can become contaminated with hot engine oil, either due to poor maintenance, an oil seal failure or certain design issues. Aircrew and passengers on airliners can then be exposed to highly toxic contaminants through the cabin air supply due to toxins contained in engine oil. UK Government figures suggest that this happens once in every 2000 flights but in all probability the frequency is far greater, due to severe under reporting and widespread ignorance of the phenomenon.