In Flight health - Air Quality


Aircraft air quality is very important for a safe, comfortable and healthy flight. Cabin air must be carefully controlled in different ways. Air is often re-circulated so must be filtered, temperature controlled, humidity controlled & pressure regulated. The system that controls most of these is known as the Environmental Control System.
In flight air quality is of interest to both pilots and passengers.

Cabin Air Pressure.

The pressure in an aircraft is not equal to the pressure at sea level, but is instead equivalent to around 1500m - 2500m in altitude. Although the effects of this are not a concern for the majority of healthy individuals, it does mean that there is a reduction in oxygen available. The cabin pressurization can also affect the human body mainly by causing internal gases to expand. Most people have experiences this do a degree during take-off or landing inside the inner ear. Expanding gasses in the body and ear can cause discomfort & potentially pain. The gas laws responsible for this are located here on Aviation Knowledge. One way to counter this is by 'equalizing' the middle ear and sinus. To read more about cabin pressure click here.


The relative humidity inside aircraft cabins during flight is generally low (usually less than 20% (Rescue Nurse International, 20122)). Our bodies aren't usually used to this low humidity and as a result we can experience slight drying of the skin, drying or sore eyes, as well as drying of the mucous membranes which can lead to cracked lips. Some modern composite aircraft (such as the Boeing 787 (wiki)) have been able to achieve higher levels of humidity.


Low humidity can also lead to dehydration. Dehydration is a common health risk for pilots. For more information on dehydration and prevention see the FAA's web page here.


Because cabin pressure is low, oxygen is also reduced slightly. This is of most concern to infants or individuals with cardio-respiratory diseases as it can reduce the oxygen saturation of the blood potentially leading to hypoxia. Others who may have increased risk include smokers (who may have reduced ability to ingest oxygen) as well as people under the influence of alcohol (as the effect of alcohol on the brain is increased by with lack of oxygen (Rescue Nurse International, 20122)).


Lack of oxygen in the cabin can lead to a condition known as hypoxia. To learn more about hypoxia click here

Airborne Allergens (Aeroallergen)

For people with certain allergies it can be very important that an aircraft's air is filtered during flight. There are a number of airborne allergens that can pose a health risk to some people. These allergens include

  • Dust mites & animal contaminants
  • Mold
  • Certain chemicals
  • And even nuts

Air filtration systems onboard can help make the flight safer for those with allergies, and can make the flight healthier and more comfortable for all passengers and crew onboard.


Annoying odors can make any flight uncomfortable, however they usually do not pose any health risk. There is the potential to cause irritation to the mucous membrane.

Air pollution

There are a variety of different pollutants that can lower the quality of an aircrafts air and potentially pose a health risk. These often source from the aircrafts engine bay. Components such as carbon seals can leak oil containing highly toxic additives into the bleed air, in what is known in the industry as a "fume event". (Wikipedia, 20121). The Most common pollutants are carbon dioxide, carbon monoxide, and ozone.

Carbon Dioxide, Carbon Monoxide & Ozone

  • Concentrations of Carbon Dioxide in aircraft are generally very low & may only pose a risk in exceptional cases.
  • Carbon Monoxide poses a larger health risk than C02, however in flight contamination is very rare and may be limited to very few incidents. Carbon monoxide can however be a silent killer. More more information and in flight examples see Carbon Monoxide Poisoning.
  • Ozone is not usually an air pollutant due to ozone converters on many aircraft, however for operators in aircraft without these converters there can be a potential risk. Ozone can negatively affect the lungs and throat (airways). Long-term exposure is correlated with an increased risk of death from respiratory illness (Wiki, 20123).

Hydraulic Fluids

Hydraulic fluids are very common in the modern aircraft. Hydraulic fluids can pose a health risk however the occurrence & risk of exposure is very low for passengers and crew (more of a health risk for maintenance personnel). Hydraulic fluids are very toxic and can pose a fire risk.


Before/after some international flights many airlines use pesticides to disinfect the aircraft to prevent the importation of certain dangerous insects. These pesticides can pose a significant health risk to both passengers and crew. Risk is compounded for crew or passenger with repeated exposure. It's hard to know if the aircraft has been sprayed recently or not as there are no requirements to inform either crewmembers or passengers prior to ticket purchase or flight (AFA-CWA, 20124). Pesticide exposure can result in;

  • Skin rashes/hives
  • Respiratory and sinus problems
  • Headache
  • Anaphylactic shock
  • And immune and neurological problems

New Age Aircraft

Some modern aircraft such as the Boeing 787(Aviation Knowledge) have improved air quality though the use of new technology and materials. The 787 is able to offer a higher humidity and air pressure making the flight more comfortable and healthy.

1. Wikipedia. (2012). Environmental control system. Retrieved 15 September, 2012 from
2. Rescue Nurse International. (2012). Cabin Environment. Retrieved 18 September, 2012 from
3. Wikipedia. (2012). Ozone. Retrieved 18 September, 2012 from
4. AFA-CWA Air Safety, Health and Security Dept. (2012). Pesticides. Retrieved 18 September, 2012 from

Want to know more?

Wiki – Air Cycle Machine
Information on an aircraft’s air conditioning system
Air Crew Health
A page offering information on many health risks in the cabin environment
Wiki - Aeroallergens
Further information on airborne allergens
Flight attendants call for end to on-board insecticides
A web article by Don McIntosh discussing the insecticide issue

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Authors / Editors


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