Yes, flying can make you sick, but the risks fall into two distinct, manageable categories. The confined environment of an aircraft increases exposure to infectious diseases from close proximity to others. Additionally, unique physical conditions inside the cabin, such as altered air pressure and low humidity, can cause non-infectious physical ailments. Understanding these mechanisms allows travelers to proactively minimize health risks associated with air travel.
Infectious Disease Transmission on Aircraft
Pathogens spread during flight primarily through respiratory droplets and contact with contaminated surfaces. The highest risk of contracting an airborne infection occurs when seated within one or two rows of an infected passenger. This immediate zone concentrates infectious aerosols and droplets before they are processed by the cabin’s ventilation system.
Modern commercial aircraft use sophisticated ventilation systems to limit pathogen spread. The air is refreshed frequently, exchanged about 20 to 30 times per hour, which is a much higher rate than in most office buildings. Approximately half of the cabin air is pulled from outside, while the other half is recirculated through High-Efficiency Particulate Air (HEPA) filters.
HEPA filters capture over 99.9% of airborne microbes, including bacteria and viruses, similar to filtration systems in hospital operating rooms. While filtration minimizes widespread airborne transmission, it offers less protection from large respiratory droplets or direct contact. Pathogens persist on shared touchpoints, such as tray tables, seatbelt buckles, armrests, and lavatory surfaces, risking transmission through hand-to-mouth or hand-to-eye contact.
Physical Ailments from the Cabin Environment
The physics of flying create a unique environment that can cause discomfort and mild illness. The cabin is pressurized to an altitude equivalent of 5,000 to 8,000 feet above sea level, lower than ground pressure. This pressure drop causes gases within the body’s cavities, such as the middle ear and sinuses, to expand.
This gas expansion can lead to barotrauma, a painful condition, especially during ascent and descent as the body struggles to equalize pressure. The cabin air is also extremely dry, with humidity often hovering between 10% and 20%, much lower than typical indoor environments. This low humidity causes mucous membranes in the nose, throat, and eyes to dry out, contributing to dehydration.
Deep Vein Thrombosis (DVT) is another concern, involving the formation of a blood clot, usually in the legs. Flights lasting four hours or more increase this risk because extended, cramped sitting slows blood flow. Reduced cabin air pressure combined with immobility can activate blood coagulation factors, further contributing to DVT risk.
Strategies for Minimizing Health Risks During Flight
Passengers can take proactive steps to mitigate both infectious and non-infectious health risks during air travel.
Preventing Infection and Dehydration
To reduce the chance of infection, wipe down high-touch surfaces like the tray table and armrests with an antiseptic wipe immediately after boarding. Frequent hand hygiene is also important; use an alcohol-based hand sanitizer after touching shared surfaces and before eating. Countering the effects of low humidity requires a focus on hydration. Passengers should drink water consistently and limit alcohol and caffeinated beverages, which contribute to dehydration.
Promoting Circulation and Equalizing Pressure
To maintain proper circulation and prevent DVT, movement is necessary, especially on long-haul flights.
- Stand up and walk the length of the aisle every one to two hours.
- While seated, perform simple exercises such as ankle circles and calf raises to stimulate blood flow in the lower legs.
- To manage ear and sinus pressure changes during takeoff and landing, actively swallow, yawn, or chew gum.
- Utilize the Valsalva maneuver—gently blowing air against a pinched nose—to help equalize pressure and relieve discomfort.