In-flight medical emergencies have become more frequent, with a study showing one in every 212 flights now experiences an incident, up from one in 604 in 2013. While air travel remains safe overall, the unique cabin environment poses challenges to the human body that can trigger health problems.
Cabin pressure and oxygen levels
Aircraft cabins are pressurised to the equivalent of up to 8,000 feet above sea level. This reduces available oxygen to about 15% compared to 21% at sea level, according to Professor Adam Taylor of Lancaster University. Healthy individuals may not notice, but those with cardiopulmonary conditions like COPD or hypertension face increased risks.
Dehydration and fluid loss
Cabin humidity is very low, causing passengers to lose up to 360ml of water per hour. This dehydration thickens the blood, straining the heart and raising the risk of deep vein thrombosis. Alcohol and salty foods exacerbate fluid loss.
Fainting and gastrointestinal issues
Fainting occurs in at least one in three airline emergencies, often due to postural hypotension. Gas in the intestines can expand to four times normal volume at altitude, leading to discomfort or rare emergencies like the 2023 flight diverted due to a passenger's diarrhoea.
Cardiac events and other risks
Most in-flight deaths are from cardiac events, with poorer outcomes than on land due to limited medical equipment and trained personnel. Recent dental work, surgery, or diving within 48 hours can increase complication risks.
Preventive measures
Experts recommend drinking water, moving every two hours, limiting alcohol, and taking medications on schedule. The captain decides on emergency landings based on crew and medical input.
