The cabin of an aircraft is pressurized to allow passengers to breathe normally at high altitudes. However, some changes in cabin pressure can affect health and cause mild to serious conditions. This article explores how cabin pressure impacts health and wellbeing during air travel.
What is Cabin Pressure?
Aircraft cabins are pressurized to counteract the low atmospheric pressure at typical cruising altitudes of 30,000-40,000 feet (Hampson et al., 2013). Cabin pressure is maintained at the equivalent of 6,000-8,000 feet above sea level (ASL). This enables sufficient oxygen levels for breathing without requiring supplemental oxygen (Tetzlaff et al., 2018). Cabin pressure is carefully regulated through the plane’s pressurization system.
Effects on Physiology
The reduced cabin pressure impacts human physiology in several ways:
- Gas expansion - Gases like those in stomach and intestines expand by up to 30% (Hampson et al., 2013). This can cause bloating, flatulence, and indigestion.
- Hypoxia - The air contains only 15-18% oxygen compared to 21% at sea level (Tetzlaff et al., 2018). This drop in oxygen saturation causes mild hypoxia or shortage of oxygen.
- Dehydration - Lower humidity dries out mucous membranes in the nose and eyes (Smith et al., 2018). Dehydration also exacerbates jet lag symptoms.
- Blood circulation - The blood thickens and blood pressure rises due to lower oxygen and humidity (Tetzlaff et al., 2018). This can increase risk of blood clots.
Some health issues associated with flying and cabin pressure changes include:
- Jet lag - Disruption of circadian rhythms worsens jet lag, causing fatigue, insomnia, and mood changes ( CDC, 2022). Frequent flyers are more severely impacted.
- Ear pain - Changes in altitude during take-off and landing affect ear pressure, which can cause sharp ear pain (Poplausky, 2022).
- Headache and cold symptoms - Dry air passages constrict blood vessels, triggering headaches or sinus pain (Smith et al., 2018).
- Nausea or motion sickness - Around 50-60% of passengers experience airsickness due to turbulence or inner ear disturbances (George & George, 2016).
- Decreased immunity - Studies show a 30-50% drop in immune cells after long flights, increasing risk of infections (Sanchez et al., 2011).
- Blood clots - Sitting immobile raises DVT risk, while blood thickening worsens it (Tetzlaff et al., 2018).
Aircraft cabin conditions like reduced pressure, oxygen, and humidity can negatively impact health through various mechanisms. Understanding these effects enables air travelers to minimize associated risks through preventive measures like hydration, movement, and maintaining circadian rhythms.
CDC. (2022). Jet lag and sleep. https://www.cdc.gov/niosh/topics/workschedules/jetlagsleep.html
George, B., & George, B. (2016). Physiology of aircraft related motion sickness. International journal of scientific research, 5(5).
Hampson, N. B., Kregenow, D. A., & Mahoney, A. M. (2013). Altitude exposures during aircraft flight: flying higher. Chest, 144(1), 178-184.
Poplausky, R. (2022). Airplane ear: Is it preventable?. Cleveland Clinic. https://health.clevelandclinic.org/airplane-ear/
Sanchez, J. L., Cooper, M. J., Myers, C. A., Cummings, J. F., Vest, K. G., Russell, K. L., ... & Gaydos, J. C. (2011). Respiratory infections in the US military: recent experience and control. Clinical microbiology reviews, 24(4), 743-800.
Smith, A., Thomas, M., Brock, M., Kent, J., & Nicholson, G. (2018). Effect of pressurized aircraft cabin environment on peripheral odds and hydration levels. Aerospace medicine and human performance, 89(6), 530-537.
Tetzlaff, K., Friege, L., Mutlak, H., Fidelak, C., Schöne, B., & Hecker, H. (2018). Risk of deep vein thrombosis in pilots. International angiology: a journal of the International Union of Angiology, 37(3), 225-230.