Flight-related illness

Air travel has become an increasing source of pain, discomfort and illness among passengers and crew members in recent years. It has been suggested that health problems for long distance fliers are far more common than the airlines and aviation safety official either know or are willing to admit. Difficulties in documenting their extent start with the rapid dispersion of the passengers to many different points. Also, it is often hard to separate the effects of forced contact with airborne infectious organism from the immune-suppressing effect of travel-related stress, which leaves people more vulnerable to infection.

The rapidity of air transport, for example, results in disturbances of the circadian rhythm in aircrews and passengers who have to travel long distances. To economize on fuel, the newer airplanes change cabin air less frequently -- every six minutes instead of every three minutes on older models. This may mean that only 40 to 60 percent of the cabin air is renewed during the flight. Complaints have been made of headaches, nausea, double vision and the discomfort of breathing stale air. Lack of movement, cramped seats and the pressure of seat cushions on the back of the thighs impairs circulation in the legs, often resulting in swollen ankles and feet and sometime in dangerous blood clots in the lower leg than can, days later, break loose and lodge in the lungs (causing flight-related pulmonary embolism dubbed called "economy class syndrome". Dehydration, due to dry cabin air, decreased consumption of water and the dehydrating effect of other beverages, can cause general discomfort, digestive problems, undue fatigue and worsened jet lag. Low humidity levels (typically of around 10%) can cause eyes to become sore and red and the upper respiratory passages to dry out, increasing their susceptibility to infection.

Cabin pressure corresponds to a height of between 1,800 to 2,000 metres above sea level. This low pressure hinders the exchange of gases in the lungs, who oxygen intake is then reduced unless heart and lungs work faster. It is also more difficult for lungs to expel nitrogen, which concentrates in the blood stream and contributes to the selling of limbs. Variations in pressure during the flight may result in injuries to the ear, the sinuses, and sometimes the teeth. Airsickness, and fainting following hyperventilation provoked by anxiety, are not uncommon. As the plane descends and outside pressure builds, the Eustachian tube in the middle ear tends to collapse and the middle ear may fill with fluid and blood, and even rupture if the Eustachian tube is blocked with the mucous of a cold or upper respiratory infection. But the most frequent hazard is constituted by the accidents, usually slight but sometimes serious, caused by turbulence.

To counter disease-bearing pests, certain governments require flight attendants to spray d-phenothrin 30 minutes before landing at airports in the Caribbean, South America and South Pacific. Whilst of low toxicity to humans, the insecticide can create problems for people with allergies, chemical sensitivities, asthma and other conditions. Symptoms of headaches, nausea, fatigue, seizures, and in extreme instances, memory loss, cognitive skills loss or a depressed immune system, have been claimed by passengers and flight attendants.