Air quality on board

Contact person
Marian Kortas
Head of Operations, Engineering & Safety
+49 30 520077-170 marian.kortas@bdl.aero
Ivo Rzegotta
Head of Strategic Planning and Communication
+49 30 520077-165 ivo.rzegotta@bdl.aero

At 12,000 meters cruising altitude it becomes uncomfortable – at least outside the aircraft: the outside temperature is -50 degrees Celsius and there is a massive pressure difference from that on the ground, which means that there is hardly any air left and therefore no oxygen. The pilots and passengers on board, however, do not feel a thing, because they are well protected by the aircraft cabin.

This is how the fresh air supply in the aircraft works

On board an aircraft, two to three independently operated air conditioning systems ensure optimum conditions: they regulate the temperature, pump the missing pressure into the aircraft and constantly supply the cabin with fresh air. The used air is extracted at the same time.

The supply of air on board is very complex: usually, outside air is sucked in by the engine, which runs at over 12,000 revolutions per minute. The air is strongly compressed and drawn off before combustion. This “bleed air” is then transported into the aircraft by the air conditioning system. In addition, special filters purify the air consumed on board so that it can be reused. Around 50 percent of the cabin air circulates in this way. The highly effective filters specially used for this purpose – called HEPA filters or high-performance particle filters – clean the cabin air of bacteria, viruses, pollen and dust. The cabin air filtered in this way is cleaner than the air in any residential or commercial building.

In addition, BDL member airlines and other airlines are currently running test series for an expansion with HEPA carbon filters. These newly developed filters are equipped with an activated carbon filter. This also filters odorous substances and volatile organic compounds (e.g., combustion residues from kerosene, oil or de-icing).

Engines, air conditioning systems and filters are regularly checked and serviced to ensure that the high quality of cabin air is constantly maintained.

How is the quality of the cabin air ensured?

Nevertheless, in recent years the question has repeatedly arisen as to whether the health of passengers and crews as well as flight safety could be endangered by the ingress of substances such as burnt oil residues or other pollutants into the cabin air. It is therefore of particular concern to the airlines to find out whether there are reliable findings from scientific studies that confirm these risks and whether there is a problem that requires changes in flight operations or in the construction and maintenance of aircraft.

To ensure safe flight operations, binding regulations, tasks and responsibilities in aviation exist for the companies and supervisory authorities involved. It is the responsibility of the airlines to ensure the proper and safe operation of their aircraft and to strictly observe all maintenance and servicing regulations. The BDL is also in dialog with aircraft and engine manufacturers as well as producers of oils, sensors and filters in order to jointly avoid all potential hazards to cabin air in the future.

Active reporting system

Any incident involving strange odors on board is investigated. This includes a consistent reporting system. Pilots and flight attendants report such incidents not only to their airlines but also to the German Federal Bureau of Aircraft Accident Investigation (BFU) in accordance with the statutory reporting requirements. The BDL actively supports this reporting system through regular discussions with the companies and with the trade unions of pilots and flight attendants, the Vereinigung Cockpit (VC), the Unabhängige Flugbegleiter Organisation (UFO) and the Vereinte Dienstleistungsgewerkschaft (ver.di). The airlines and their crews work together to ensure that the air in the aircraft is constantly monitored.

In order to ensure that no health hazards arise when unidentifiable odors occur on board, the German airlines, representatives of the cockpit and cabin crews, Berufsgenossenschaft Verkehr and medical doctors and scientists have developed a medical examination procedure. In the process, the standardized collection of medical data enables Berufsgenossenschaft Verkehr to recognize and evaluate possible correlations and to draw medical conclusions.

The European Aviation Safety Agency (EASA) also accurately monitors all reports on cabin air quality. In an in-depth three-year study completed in 2012, it came to the conclusion that the cabin air in commercial aircraft is safe. This has been confirmed since by two more studies: independent studies on cabin air measurements during flight and on the toxicity of pyrolyzed engine oils carried out between 2015 and 2017 and initiated by EASA confirmed the authority’s earlier assessments. No emission limits were exceeded on any flight, and no substances of a concentration harmful to health were detected.

The studies thus confirm tests of the cabin air that had been previously commissioned by the aviation industry and always showed the same result: the cabin air in the aircraft is safe for the health of passengers and crews. The BDL welcomes the fact that in the interest of the public, passengers, airlines, industry associations and industry, the EU Commission is continuing the EASA studies.

Together, German aviation wants to ensure that flying will continue to be safe for our passengers and employees in the future.