There are many reasons for contamination of the cabin air, the most common possibilities are briefly explained below:
- Breathing air in most aircraft is supplied via bleed air, which is fed directly into the aircraft cabin unfiltered from one of the engine compressor stages. The engine itself, of course, only works because of a complex mechanics that floats in a special engine oil, which is only approved for the aviation industry and is enriched with various neurotoxic additives, e. g. different organophosphates. These protect the mechanical components from premature wear and tear, but are extremely hazardous to health. Depending on the design, smaller and larger quantities of this engine oil can regularly enter the compressor due to leaking or defective pressure seals, evaporate there and thus enter the aircraft cabin with the bleed air. This also happens in case of overfilling with engine oils, but above all because of improper maintenance and repair work that has not been carried out in accordance with the manufacturer’s specifications and because the service life of the engines has meanwhile been extended immensely before they are overhauled. The defective compression seals can only be replaced by an extension of the drive unit, which is correspondingly time-consuming.
- When the engines are started and when taxiing over the apron to the runway, exhaust gases present in the outside air are sucked in and also conducted into the cabin. These are mostly from aircraft in front and take-off planes.
- In winter the aircraft must be de-iced. Residues of this de-icing fluid can get into the engines and thus enter the cabin interior.
- aircraft are regularly sprayed with hazardous pesticides and insecticides. These are heavy sprays that adhere to the interior, e. g. the carpet, to achieve a long-term effect. These substances emit gases and can pose a health hazard.
- Before landing in certain countries, aircraft crews are required by law to spray the interior of the aircraft with pesticides, above the heads of seated passengers. The empty cans must be shown to the local authorities. These substances are proven to be harmful to health and can even damage the genetic material.
- Interior coverings, carpets and seats are treated with special fire retardant materials and impregnating agents, the carpets are laid with solvent-based adhesives. These substances are released and thus additionally released into the breathing air.
- Special short- and medium-haul aircraft in particular are not equipped with the necessary ozone filters for cost reasons, so that the breathing air is contaminated with the demonstrably harmful gas, which is present in the ambient air at cruising altitude in sometimes high concentrations.
It should be noted that contamination of the cabin air is not a monocausal cause, but that a wide variety of mixtures of substances, which are constantly changing in composition and harmful to health, play a causal role. However, the susceptible bleed air system can be regarded as the main cause.