Is the air in an aircraft cabin really full of germs?
Among the myths about civil aviationone of the most recurrent is the disease transmission on aircraft. COVID-19, Ebola or the case a few years ago of SARS (Severe Acute Respiratory Syndrome), should not reach our countries through infected air travellers, so the authorities are taking measures to limit the risk of an infected person leaving a contaminated area. But apart from these special situations (sitting next to a person infected by a virus is not desirable, on a plane or anywhere else), is the air in aeroplanes really as impure as we imagine it to be?
Numerous studies have shown that the air we breathe in an aeroplane is much cleaner than in any other mode of transport.
It is actually very clean compared to the air we normally breathe. In all modern aeroplanes, passengers breathe in a mixture of fresh air and recycled airThis allows the cabin temperature to be regulated while maintaining an acceptable level of humidity. There are no air reserves in an aircraftBut while flying, it is possible to capture the outside air, which is extremely pure at this altitude. Obviously, this air is not injected directly into the cabin because it is very dense and, moreover, because it is at a temperature of around -50°C.
Outside air is first drawn in by the engine and passes through its compressors, leading to a significant increase in temperature, with two consequences: all harmful micro-organisms are destroyed y the air loses almost all of its humidity as well.. This is very uncomfortable for passengers, as it dehydrates us more quickly, tugs at our skin and causes itchy eyes. It should be noted that there is no direct contact of this air with the combustion gases and therefore no risk of breathing paraffin fumes. The air is cooled, compressed and injected into the cabin at the atmospheric pressure existing at an altitude of about 1,600 metres, which is acceptable for everyone, including asthmatics.
There are at least two pneumatic air intake systems on aircraft. Air is injected from the top of the aircraft (through the air vents and individual aerators above each seat) and sucked in under the fuselage. The air is then evacuated in two parts: half is blown out of the aircraft while the other half is returned inside already filtered and mixed with fresh air taken directly from outside. According to Boeing, filters can capture between 94% and 99,97% (for the B787) of microbes, a record number. In the end, this continuous cycle is so efficient, that all the air in the aircraft is renewed every two to three minutes. Numerous studies have shown that the air we breathe in an aircraft is much cleaner than the air we breathe in any other mode of transport or enclosed space, including an air-conditioned office or a room with open windows.
The only complaint we can really have about the air in an aircraft is its humidity levelUsually found in values between 5-10%The dryness reduces the efficiency of the nasal mucous membranes and can lead to increased sensitivity to viruses in the hours after each flight. This dryness reduces the efficiency of the nasal mucous membranes and can lead to increased sensitivity to viruses in the hours after each flight. Expensive and powerful systems are available to humidify the air, but they are not very effective and have annoying side effects, such as accelerated corrosion problems or the appearance of condensation droplets. The latest aircraft designed by Boeing and Airbus (respectively the B787 and A350) take the issue of passenger comfort into account from the outset. In these aircraft, the humidity level is doubled to more than 15%, a performance that is also helped by the use of corrosion-resistant carbon fibres.
There is one final issue to note: You will surely have seen the aircraft crew spreading the contents of a spray all over the plane. This is not a disinfectant at all, but merely a insecticideharmless to humans. Its sole purpose is to killing mosquitoes who have the fantastic idea of boarding with the passengers, because in this case the risk is real (mosquitoes infected with tropical diseases). Since the 1960s, thirty cases of malaria have been recorded in France in people living near an international airport, a curious fact as these people had never left the city.
So you can breathe easy on your next flights, the air in the plane will always be cleaner than the air on landeven more than that of his own home.
Xavier Tytelman
Aviation Safety Specialist
Aeronautical blogger (blog-peuravion.fr)
Head of the Fear of Flying Treatment Centre (www.peuravion.fr)
