It’s a popular misconception that, because cabins are pressurised, the cabin air remains locked in there with you. Some erroneously believe you’re breathing the same cabin air for the duration of your flight. In truth, the air in your aircraft cabin is constantly refreshed. It is pulled directly from the skies you fly through, where the atmosphere is sterilised naturally at altitude. This air is re-sterilised by the engines operating at high heat. The hot air is cooled down and distributed to your cabin while the old air is extracted.
The process is not dissimilar to the climate controls in your car, where a blend of outside air is pulled in through the engine, cooled through the air conditioning system, and then piped to you through the vents. Except, aeronautical engineers design cabin air systems to function in high-altitude life-critical conditions where the outside environment is quite different from the road.
Cabin air management technologies vary by aircraft type. All maintain a close balance between incoming fresh and outgoing stale air to ensure stable pressure in the cabin. The prime consideration is your comfort and safety. Because aircraft fly at different altitudes, the aircraft manufacturer selects cabin air management systems which maintain stable cabin pressurisation while meeting the climate control needs of passengers.
Aircraft equipped with a fresh air system constantly circulate fresh outside air into the cabin. Fresh outside air replaces the total volume of cabin air approximately every two minutes. Many business jet aircraft models use fresh air systems.
Other aircraft systems simply replace the air in the cabin at a slower rate to ensure adequate humidity levels and for better climate control. Systems that recirculate a portion of the cabin air often use HEPA (High-Efficiency Particle Arrestance) filters to purify the air in the cabin. These filters use advanced fibres, which trap pollutants and pathogens, so when the cabin air is processed, it is nearly sterile. To be classed as HEPA filters, they must trap a minimum of 99.97% of contaminants at 0.3 microns in size.
Why do microns matter? Microns measure tiny things—fine particles. A single strand of hair measures around 70 microns in diameter and is 30 times larger than the largest fine particle.
Your body filters out and expells larger irritants, but particles ranging from 0.3 to 0.9 microns can slip through the body’s natural defences. The same HEPA filters that trap very tiny particles on your plane are installed in surgical rooms where eliminating pathogens and pollutants in the air is essential.
Partial air recirculation systems typically replace the full volume of cabin air with fresh air from outside the aircraft every four minutes. The recirculated air purified through the HEPA filters is mixed with naturally sterilised outside air and temperature adjusted before being distributed back into the cabin.
Some aircraft use Ionization Systems to eliminate pollutants, pathogens, and unpleasant odours from the cabin. These electronic systems produce positive and negative ions using the hydrogen and oxygen molecules already present in the water vapour in the air. The ions trap germs, viruses, and particles and destroy them. Aircraft with Ionization Systems installed also blend naturally sterilised outside air with the portion of ionically purified air.
Commercial airline aircraft also use similar air replacement systems and air purification HEPA filters to maintain air quality, eliminating pathogens and irritants. The difference is that when you travel commercially, you travel in a large group. You’re going through a crowded airport terminal with strangers seated near you on the plane.
When flying by private jet, you avoid crowds and fly with people you know, which should also help you breathe easy. Do not hesitate to ask your LunaJets advisor if you have questions or concerns.