Needless to say, the terrible events of September 11, 2001, have made air travel more worrisome and difficult than ever. But while you can't do much to prevent terrorism and crashes, you can do quite a lot to protect yourself from the more common health hazards of flying.
Modern jetliners must control the air pressure and oxygen content of the cabin. They do a great job, but the pressure and oxygen levels are substantially below those at sea level. Cabin air is also much drier than normal, and because it's in limited supply, it's constantly recirculated. Space is also at a premium, so passengers are squeezed into tight seats. And the chief advantage of air travel also poses a medical challenge: Passengers often arrive in new time zones with their biological clocks on their old time. Add the disorienting effects of motion, stress, and limited medical resources on the plane, and you'll see why air travel can be a challenge to your health.
Here are some of the medical issues confronting today's air traveler.
Air pressure and oxygen levels get progressively lower the higher you go. As you descend, the air pressure rises. These changes in air pressure have three important implications.
1. Oxygen levels. Commercial flights provide plenty of oxygen for healthy people, but patients with serious heart or lung disease must be careful.
2. Sinuses and ears. During rapid ascents and descents the outside pressure changes much more rapidly than the internal pressure. It's why our ears "pop" under the best of circumstances. The pressure difference can persist, causing serious pain, dulled hearing, or sinus and ear infections.
Fortunately, it really does help to chew gum and swallow often. Another simple remedy is to pinch your nostrils closed between your thumb and index finger as you gently exhale with your mouth closed.
3. Intestinal gas. In most cases, you will feel nothing more than mild bloating. But gas can be a problem if you've had abdominal (or, for that matter, chest) surgery within a week or two.
Any form of prolonged sitting can trigger the problem, but air travel compounds the risk by its cramped quarters and dry air, which makes the blood "thicker" and "stickier."
Inactivity allows blood to stagnate in your leg veins, and prolonged sitting adds to the problem. Blood clots in the legs can cause pain and swelling or they can be entirely imperceptible. In either case, clots can break off and travel to the lungs, producing a potentially life-threatening medical emergency.
Mobility is the key. Whenever possible, get more leg room. Don't cross your legs. Stretch, massage your lower legs, and pump your feet up and down for about 30 seconds every 30 minutes. Take a walk in the aisle at least once every hour or so. Drink plenty of fluids.
Passengers at extra risk should consider breaking up very long flights into shorter segments. Compression stockings can also help; by gently squeezing the leg veins, they make it easier for the body to keep blood flowing up to the heart
Are passengers at risk of being infected by fellow travelers? It's a common concern, particularly in the aftermath of SARS. But a modern airliner should not be any riskier than a crowded bus or theater — and it's probably safer than a packed emergency ward waiting room.
But even if cabin air doesn't present a hazard, your seatmate may. To maximize the air exchange in your row, keep your overhead vent open. And if your neighbor is less considerate, you may want to consider wearing a mask, particularly if you have a realistic worry about a serious infection like influenza.
Cabin air lacks an important ingredient: water. Because the typical humidity is only 5%–10%, you lose water every time you exhale. To prevent dehydration, drink early and often, but don't rely on caffeinated or alcoholic beverages.
To minimize stress, arrive early and use your extra time to stroll through the airport instead of sitting in a noisy departure lounge. Dress comfortably. Keep your travel documents secure but handy and carry an extra driver's license as good insurance against loss or theft Relaxation techniques, including deep breathing, progressive muscle relaxation, and meditation, can help dissipate stress.
It's a real problem when your destination is three or more time zones away. Symptoms include fatigue and fragmented sleep at night, irritability, impaired performance, headache, loss of appetite, and irregular bowel function. Although many schemes have been proposed, there is no sure way to prevent jet lag.
All in all, a few commonsense suggestions seem best: Get plenty of rest before your trip. Try to sleep on "red-eye" flights. Keep your schedule as light as possible on your arrival day; try to avoid driving and any activities that require mental effort and good judgment. If possible, break long trips into shorter segments.
If you are prone to motion sickness, travel on an empty stomach. Try to get an aisle seat toward the center of the cabin. Keep your seat upright, minimizing head movement. Don't read or watch videos during bumpy spells. Medications can also help.
Patients with serious medical problems should check with their doctors before they travel.
If you depend on medications, pack an extra supply in your carry-on bag to guard against lost luggage and unforeseen delays or detours. Since needles are a prickly issue these days, check with your airline or the Transportation Security Administration. If you have complicated problems, carry information about your illnesses, medications, and allergies.
If you feel sick in the air (or in the airport), ask for help. Airlines all carry emergency medical kits, and as of May 2004, all airplanes with at least one flight attendant have been required to carry automated external defibrillators to treat cardiac arrest.
October 2006 Update