Commercial aircraft normally cruise at 10 to 11 km altitude. In order to create living conditions in those altitudes, cabin pressure is necessary. It is therefore possible to get conditions corresponding to an altitude of 2400 m. The air volume is approx. 1,5 fold. Air humidity is reduced to less than 10%. The blood's oxygen saturation is reduced by approx. 5%, which means for healthy passengers a reduction of blood saturation from 98% to 93%.

Oxygen (O2): Under cruising conditions the blood's oxygen saturation is reduced by approx. 5 % (98 % to 93 %). Healthy passengers do not notice the reduced oxygen saturation! Passengers with chronic lung disease, heart-circulation problems or persons who are anemic as a consequence of blood loss after an accident/operation might need additional oxygen. Austrian Airlines provide additional oxygen for their passengers if ordered 2 to 3 days prior to departure

Carbon Dioxide (CO2): The passengers exhale CO2 in the cabin, which is the end product of the human metabolism. High CO2 concentration can cause slight dizziness and a daze state. The high air exchange rate on board meets the officially required limits for the cabin air.

Ozone: The ozone affects the mucous membrane beyond 70° northern latitude. In modern long-range aircraft, an installed ozone-converter avoids this effect.

Biological Air Elements: The highly efficient air filter eliminates bacteria, viruses and fungus to a large extent. Approx. every 5 minutes the cabin air is filtered. The airlines also renew these air filters at certain periods - depending on the aircraft manufacturer's conditions and the aircraft type. Infectious spreading on board is therefore extremely seldom when considering the number of passengers travelling every year (more than 1.5 billion).

Air Humidity: The low air humidity on board can cause irritations of the eyes and the mucous membranes of the upper respiratory organs if the passenger does not supply his body with enough fluid. Under long-haul conditions the humidity can decrease to less than 10%, due to the fact that external air, used for the air conditioning, is almost dry.

Drinking fluids such as plain water, tea, fruit juice etc.

There are hardly any technical measures to increase the low humidity. In order to offer a slightly higher humidity, tons of water would be necessary. This would make flights unprofitable, because corrosion damages would cause high maintenance costs.