What has given rise to much public concern in recent years is the topic of effects on health of travelling by air. As a result, a significant minority of air travellers have developed some real fear for their health when flying, and the media and elsewhere have come to feed upon these fears. Hardly a day doesn't go by that a major newspaper doesn't carry a story about inflight medical care. The medical profession insists that people should look at the facts set out in both government and airline reports in an open-minded manner. Dr. Toshiro Makino, who heads the Nippon Medical School clinic at Tokyo's Narita International airport, points out that prolonged travel by bus or auto can produced the same effects as flying. "Fundamentally it's up to each traveller to be aware of their own health condition and use a bit of common sense," he said.

The most at risk for flight-related illnesses are the overweight and the elderly. Under normal circumstances, these same people would not go SCUBA diving or attempt to climb a mountain, but they do nothing about taking precautionary measures when they board a plane that will take him 40,000 feet above sea level. Commercial jet aircraft have to maintain a relative cabin altitude between 5,000 and 8,000 feet during routine flight. What it means is lowered oxygen content, and the air extracted from the outside environment at the high altitudes to be mixed with recycled air is extremely dry, causing the inside cabin humidity to remain low, ranging anywhere from 10 to 20 percent. This low humidity affects certain medical conditions, most notably those involving the respiratory passages and skin.

THAI has long been conscious of our passengers needs as well as comforts. Flight attendants, for example, are trained to make sure passengers have enough water throughout the flight to prevent dehydration. We recommend that passengers prepare for a flight long before it takes place. How many times have we heard someone say they can't wait to go on vacation. They are looking forward to a routine of exercise and healthy living, getting into shape, and maybe even "losing some weight." Would not a vacation be much better if that passenger was "in shape" before he or she set out and didn't have to worry about sore muscles and tired limbs. It's also important to avoid pre-flight stress. One should obtain an adequate amount of sleep before beginning a trip, and try not to spend the night before packing and making last minute arraignments.

Although these unique factors of long-distance flying do not pose a health or safety threat to most customers, there are guidelines you can follow that will improve your comfort level during and after a flight. Most medical authorities agree on a few basic rules. Most important is that passengers should stretch and perform isometric leg exercises and simple arm movements, especially during long flights involving prolonged cramped seating arrangements. While seated, you can do some simple exercises that may be effective at increasing the body's blood circulation and massaging the muscles. We recommend you do these exercises for three or four minutes every hour and occasionally get out of your seat and walk down the aisles. Each exercise should be done with minimal disturbance to other passengers. None of the following exercises should be performed if they cause pain or cannot be done with ease.

1. Ankle Circles. Lift feet off the floor. Draw a circle with the toes, simultaneously moving one foot clockwise and the other foot counterclockwise. Reverse circles. Do each direction for 15 seconds. Repeat if desired.

2. Foot Pumps. Foot motion is in three stages. First, start with both heels on the floor and point feet upward as high as you can. Second, put both feet flat on the floor, and third, lift heels high, keeping balls of feet on the floor.

Continue these three stages with continuous motion in 30-second intervals.

3. Knee Lifts. Lift leg with knee bent while contracting your thigh muscle. Alternate legs. Repeat 20-30 times for each leg.

4. Neck Roll. With shoulders relaxed, drop ear to shoulder and gently roll neck forward and back, holding each position about five seconds. Repeat five times.

5. Knee To Chest. Bend forward slightly. Clasp hands around the left knee and hug it to your chest. Hold stretch for 15 seconds. Keeping hands around the knee, slowly let it down. Alternate legs. Repeat 10 times.

6. Forward Flex. With both feet on the floor and stomach held in, slowly bend forward and walk your hands down the front of your legs toward your ankles. Hold stretch for 15 seconds and slowly sit back.

7. Shoulder Roll. Hunch shoulders forward, then upward then backward, then downward, using a gentle circular motion. An important consideration is the ill effects of dehydration. The human body dehydrates rapidly at high altitudes. We recommend that you:

• Drink water and juices frequently during your flight.
• Drink coffee, tea and alcohol in moderation. These drinks increase the body's dehydration.
• Remove contact lenses and wear glasses if your eyes are irritated.
• Use a skin moisturiser to refresh the skin.
• Avoid over-eating just prior to and during the flight. It is difficult to digest too much food when the body is inactive.

And last, get all the sleep you can get. Plan on sleeping the same amount of time in a 24-hour period as when at home. Limit use of hypnotic sleep medications to short-acting agents for only a few dosages to avoid dependence and hangover effects.

If the time spent at a destination is less than one day, attempt to stay on home time. Otherwise, try to adjust quickly to the new time zone by remaining active during the daylight hours and adopting local mealtimes. Air travel should be delayed after SCUBA diving to minimize the chance of developing decompression sickness, and immediately after surgical operations, especially internal operations. And contrary to the belief that recycled air is harmful, risk of infection from microorganisms in airline cabin air is lower than in ordinary city locations.

As a last reminder, medical research indicates passengers most acceptable to air sickness include:

• increasing age above 40 years
• pregnancy
• former or current malignant disease
• blood disorders leading to increased clotting tendency
• personal or family history
• recent major surgery or injury, especially to lower limbs or abdomen
• oestrogen hormone therapy, including oral contraceptives
• immobilisation for a day or more
• dehydration
• varicose veins
• obesity
• tobacco smoking

If you fall into one of these categories or you have any concerns about your health and flying, THAI recommends you seek medical advice before travelling. Remember, children and infants might experience some discomfort because of pressure changes during climb and descent.

If you are suffering from nasal congestion or allergies, use nasal sprays, decongestants and antihistamines 30 minutes prior to descent to help open up your ear and sinus passages.

If you have a cold, flu or hay fever, your sinuses could be impaired. Swollen membranes in your nose could block your Eustachian tubes - the tiny channels between your nasal passages and your middle ear chamber. This can cause discomfort during changes in cabin pressure, particularly during descent.To "clear" your ears, try swallowing and/or yawning. These actions help open your Eustachian tubes, equalising pressure between your middle ear chamber and your throat.

When flying with an infant, feed or give your baby a dummy during descent. Sucking and swallowing will help infants equalise the pressure in their ears. And finally we come to jet lag. The main cause of jet lag is travelling to a different time zone without giving the body a chance to adjust to new night-day cycles. In general, the more time zones you cross during your flight, the more your biological clock is disturbed. The common symptoms are sleeplessness, tiredness, loss of appetite or appetite at odd hours. We recommend that you:

• Get a good night's rest before your flight.
• Arrive at your destination a day or two early, if possible, to give your body a chance to become more acclimatised to the new time zone.
• Fly direct to minimise flight time, when possible. This allows you to relax more upon arrival.
• Leave your watch on your home time if you're staying at your destination less than 48 hours. Also, try to eat and sleep according to your home time.
• Change your watch to the local time if your stay is longer than 48 hours, and try to eat and sleep in accordance with the local time. On longer stays, try to prepare in advance for your destination with its different time zone, adjust your meal and rest times to be closer to those of your destination.
• Try some light exercise, go for a brisk walk, or do some reading, if you can't sleep after arrival at your destination. It generally takes the body's biological clock approximately one day to adjust per time zone crossed.

We hope this short introduction will clear up some of the mysteries of long-distance flying. We at THAI try to make flying, the getting there, as enjoyable as possible. We provide our passengers with the latest inflight service with everything from gourmet meals to the last movies. After all, flying is part of travelling, and much like travelling aboard a cruise ship or by your own private car, it's all what you make of it. And remember, we want our passengers to "fly sabai" .