Worldwide, an estimated 3.6 billion people travel by commercial aircraft every year, and this number continues to rise. Travelers often have concerns about the health risks of flying in airplanes. Those with underlying illness need to be aware that the entire point-to-point travel experience, including buses, trains, taxis, public waiting areas, and even movement within the airport, can pose challenges. Although illness may occur as a direct result of air travel, it is uncommon; the main concerns are:
- Exacerbations of chronic medical problems due to changes in air pressure and humidity
- Relative immobility during flights leading to thromboembolic disease (see Deep Vein Thrombosis & Pulmonary Embolism in this chapter)
- Close proximity to other passengers with communicable diseases
Preflight Medical Considerations
During flight, the aircraft cabin pressure is usually maintained at the equivalent of 6,000–8,000 ft (1,829–2,438 m) above sea level. Most healthy travelers will not notice any effects. However, for travelers with cardiopulmonary diseases (especially those who normally require supplemental oxygen), cerebrovascular disease, anemia, or sickle cell disease, conditions in an aircraft can exacerbate underlying medical conditions. Aircraft cabin air is typically dry, usually 10%–20% humidity, which can cause dryness of the mucous membranes of the eyes and airways.
The new Boeing 787 and Airbus A 350 have improved the cabin environment: a greater number of temperature zones, a higher humidity of 25%, a faster time to refresh cabin air, lower ambient noise, and multiple shades of LED lighting. These, along with a cabin air pressure equivalent to an altitude of only 2,000 ft, should provide more comfort and ease jet lag.
The Aerospace Medical Association (www.asma.org) recommends evaluating chronic medical conditions and addressing instabilities prior to travel, particularly in those who have underlying cardiovascular disease, a history of deep vein thrombosis or pulmonary embolism, chronic lung disease, surgical conditions, seizures, stroke, mental illness, or diabetes.
For information on contraindications and precautions related to flying during pregnancy, see Chapter 7, Pregnant Travelers. Specific information for travelers with disabilities and medical conditions that may affect security screening can be found at www.tsa.gov/travel/special-procedures. For those who require supplemental in-flight oxygen, the following must be taken into consideration:
- Travelers must arrange their own oxygen supplies while on the ground, at departure, during layovers, and upon arrival.
- Federal regulations prohibit airlines from allowing passengers to bring their own oxygen onboard; passengers requiring in-flight supplemental oxygen should notify the airline ≥72 hours before departure.
- Airlines might not offer in-flight supplemental oxygen on all aircraft or flights; some airlines permit only Federal Aviation Administration (FAA)-approved portable oxygen concentrators. Information to assist people who require supplemental oxygen during travel and FAA-approved portable oxygen concentrators can be found at the FAA website: www.faa.gov/about/initiatives/cabin_safety/portable_oxygen.
- Information regarding the screening of portable oxygen concentrators at airports in the United States can be found at www.tsa.gov/blog/2014/04/08/tsa-travel-tips-traveling-portable-oxygen.
For more information, see Chapter 5, Travelers with Disabilities.
Barotrauma During Flight
Barotrauma can occur when the pressure inside an air-filled, enclosed body space (such as the middle ear, sinuses, or abdomen) is not the same as the air pressure inside the aircraft cabin. It most commonly is the result of rapid changes in environmental pressure, such as during ascent, when cabin pressure rapidly falls, and during descent, when cabin pressure rapidly rises. Barotrauma most commonly affects the middle ear; it happens when the eustachian tube is blocked and thus unable to equalize the air pressure in the middle ear with the outside cabin pressure. Middle ear barotrauma is usually not severe or dangerous and can usually be prevented or self-treated. It may rarely cause complications such as a perforated tympanic membrane, dizziness, permanent tinnitus, or hearing loss. The following suggestions may help avoid potential barotrauma:
- People with ear, nose, and sinus infections or severe congestion may wish to postpone flying to prevent pain or injury.
- Oral or nasal decongestants may alleviate symptoms.
- Travelers with allergies should continue their regular allergy medications.
- Travelers should stay hydrated to help avoid irritation of nasal passages and pharynx and to promote better function of the eustachian tubes.
- Travelers sensitive to abdominal bloating should avoid carbonated beverages and foods that can increase gas production.
- People who have had recent surgery, particularly intra-abdominal, neurologic, intrapulmonary, or intraocular procedures, should consult with their physician before flying.
Ventilation and Air Quality
All commercial jet aircraft built after the late 1980s, and a few modified older aircraft, recirculate 10%–50% of the air in the cabin, mixed with outside air. The recirculated air passes through a series of filters 20–30 times per hour. In most newer-model airplanes, the recycled air passes through high-efficiency particulate air (HEPA) filters, which capture 99.9% of particles (bacteria, fungi, and larger viruses or virus clumps) 0.1–0.3 µm in diameter. Furthermore, air generally circulates in defined areas within the aircraft, thus limiting the radius of distribution of pathogens spread by small-particle aerosols. As a result, the cabin air environment is not conducive to the spread of most infectious diseases.
Some diseases may be spread by contact with infected secretions, such as when an ill person sneezes or coughs (and the secretions or droplets land on another person’s face, mouth, nose, or eyes), or touches a communal surface (such as a door knob or rest room faucet) with contaminated hands. Other people handling those contaminated surfaces may then be inoculated with the contaminant. Practicing good handwashing and respiratory hygiene (covering mouth when coughing or sneezing) decreases the risk of disease spread by direct or indirect contact.
In-Flight Medical Emergencies
The increasing number of travelers combined with an increase in the number of older passengers make the incidence of onboard medical emergencies likely to increase. Medical emergencies occur in approximately 1 in 600 flights or about 16 medical emergencies per 1 million passengers. The most commonly encountered in-flight medical events are:
- Syncope or presyncope (37%)
- Respiratory symptoms (12%)
- Nausea or vomiting (10%)
- Cardiac symptoms (8%)
- Seizures (6%)
Although in-flight medical emergencies occur, serious illness or death onboard a commercial aircraft is rare. Deaths onboard commercial aircraft have been estimated at 0.3 per 1 million passengers; approximately two-thirds of these are caused by cardiac conditions. Most commercial airplanes that fly within the United States are required to carry at least 1 approved automatic external defibrillator (AED) and an emergency medical kit.
Flight attendants are trained in basic first aid procedures such as CPR, and use of AED machines, but are generally not certified in emergency medical response. Many airlines use ground-based medical consultants to assist flight crew and volunteer passenger responders in managing medical cases. In nearly one-half of in-flight emergencies, physician volunteers have provided assistance. The Aviation Medical Assistance Act, passed in 1998, provides some protection from liability to providers who respond to in-flight medical emergencies.
The goal of managing in-flight medical emergencies is to stabilize the passenger until ground-based medical care can safely be reached. When considering diversion to a closer airport, the captain must consider the needs of the ill passenger, as well as other safety concerns such as weather, landing conditions, and terrain. Certain routes, such as transoceanic flights, and availability of definitive medical care may limit diversion options.
In-Flight Transmission of Communicable Diseases
Communicable diseases may be transmitted to other travelers during air travel; therefore, people who are acutely ill, or still within the infectious period for a specific disease, should delay their travel until they are no longer contagious. For example, otherwise healthy adults can transmit influenza to others for 5–7 days. Travelers should be up-to-date on routine vaccinations and receive destination-specific vaccinations before travel. Travelers should be reminded to wash their hands frequently and thoroughly (or use an alcohol-based hand sanitizer containing at least 60% alcohol), especially after using the toilet and before preparing or eating food, and to cover their noses and mouths when coughing or sneezing. For further information on control of communicable diseases, see Appendix D: Airplanes & Cruise Ships: Illness & Death Reporting & Public Health Interventions.
Information for Aircrew
In preparation for a healthy journey, flight crew can refer to Chapter 9, Aircrews, and to the CDC Travelers’ Health website (www.cdc.gov/travel). If flight crews encounter passengers with potentially infectious diseases, see the CDC Airline Guidance web page: www.cdc.gov/quarantine/air. Requirements and tools for reporting by aircrews are also provided there.
- Aerospace Medical Association Air Transport Medicine Committee. Medical considerations for airline travel. Alexandria, VA: Aerospace Medical Association; 2018 [cited 2018 Oct 23]. Available from: www.asma.org/publications/medical-publications-for-airline-travel/medical-considerations-for-airline-travel.
- Bagshaw M, Barbeau DN. The aircraft cabin environment. In: Keystone JS, Kozarsky PE, Freedman DO, Northdurft HO, Connor BA editors. Travel Medicine. 3rd ed. Philadelphia: Saunders Elsevier; 2013, pp. 405–12.
- Huizer YL, Swaanm CM, Leitmeyer KC, Timen A. Usefulness and applicability of infectious disease control measures in air travel: a review. Travel Med Infect Dis. 2015 Jan–Feb;13(1):19–30.
- Illig PA. Passenger health. In: Curdt-Christiansen C, Draeger J, Kriebel J, Antunano M, editors. Principles and Practice of Aviation Medicine. Hackensack, NJ: World Scientific; 2009. pp. 667–708.
- Nable JV, Tupe CL, Gehle BD, Brady WJ. In-Flight medical emergencies during commercial travel. N Engl J Med 2015 Sep 3;375(10):939–45. [PMID:26332548]
- Peterson DC, Martin-Gill C, Guyette FX, Tobias AZ, McCarthy CE, Harrington ST, et al. Outcomes of medical emergencies on commercial airline flights. N Engl J Med. 2013 May 5;368(22):2075–83. [PMID:23718164]
Paul J. Edelson, Phyllis E. Kozarsky, Clive Brown