Although aircraft cabins are pressurised, the cabin air pressure is not the same as that of the ground. Instead, it is equivalent to air pressure at the altitude of 1,500 to 2,500 metres above sea level. Consequently, the available oxygen is reduced and gases within the body expand. The effects of reduced cabin air pressure are usually well tolerated by healthy passengers.

Measures should be taken to prevent dehydration on long flights. Adequate intake of non- alcoholic beverages (e.g. water and fruit juices) should be maintained before and throughout the flight. Consumption of beverages that contain caffeine (including tea, coffee and cola) and alcohol cause dehydration; this should be restricted – preferably avoided – both before and during the flight.

Many countries require disinsection (i.e. treatment for the removal of insects) of aircraft arriving from countries where vector-borne diseases, such as malaria and yellow fever, occur. This is to prevent the inadvertent introduction of infection by insects carried on board. Disinsection is a public health measure that is mandated by the International Health Regulations. Disinsection involves treatment of the interior of the aircraft by the application of insecticides. The different procedures in use include:

• treatment of the interior of the aircraft by application of a quick-acting pyrethroid insecticide spray, with the passengers on board, immediately prior to take off.


• treatment of the interior of the aircraft on the ground before passengers come on board, using a residual insecticide aerosol containing permethrin, plus additional in-flight treatment with a quick-acting insecticide spray shortly before landing


• regular application of a residual insecticide to all internal surfaces, except in food preparation areas

Travellers are sometimes concerned about their exposure to insecticide sprays while travelling by air. They should be reassured that disinsection is a safe procedure. There is no evidence of any toxic hazard to passengers or crew resulting from the use of the recommended methods and products for disinsection.

DVT is a condition where blood clots in the deep veins of the legs. These clots can break up and travel to the heart, lungs and brain and this can lead to serious medical complications. In the air travel industry, this condition has been dubbed the "Economy Class Syndrome". However, this term is a misnomer as DVT can affect all classes of passengers on all forms of transport. Although the exact cause of DVT is not known, prolonged immobility and dehydration can increase the risk of DVT.

Other risk factors include hormone therapy (including the use of contraceptive pills), pregnancy, certain cardiovascular conditions, smoking, post-surgery, advanced cancer, obesity and other hereditary factors. Early DVT symptoms include pain, swelling and redness in the lower leg.

NOTE: Call your doctor if you have these symptoms. To reduce the risk of DVT, we recommend the following measures for all our passengers:

• Avoid high consumption of caffeine and alcoholic beverages as these cause dehydration.


• Increase consumption of other fluids, especially water or fruit juices to improve body hydration. In this respect, our cabin staff have been advised to serve water and fruit juices more frequently to passengers.


• Do simple regular in-flight workouts. One such exercise is to raise the buttocks and thighs off the seats while seated and at the same time squeezing the toes and contracting the calf muscles. Another exercise is to straighten and bend both legs at the knee while seated. Both these exercises will improve blood circulation.


• Wear loose-fitting, comfortable clothing.

Air expands in all air-filled body cavities as a result of reduction in cabin air pressure. Abdominal gas expansion may cause moderate discomfort, whereas expansion of the air in the middle ear and sinuses may cause pain, particularly during descent. As the aircraft ascends, air escapes from the middle ear and sinuses, usually without causing problems. As the aircraft descends, air must be allowed to flow back into the middle ear and sinuses in order to equalise pressure differences (i.e. "clearing the ears"). This sometimes causes discomfort but it can be alleviated by swallowing, chewing or yawning. If the problem persists, forceful expiration against a closed nose and mouth will usually help. People with ear, nose and sinus infections should avoid flying because injury may result from inability to equalise pressure differences. If problems arise during flight, detumescent nasal drops may sometimes be helpful.

Relative humidity is low in aircraft cabins, usually less than 20%. Low humidity may cause discomfort in the eyes, mouth and nose but presents little risk to health and does not result in central dehydration as long as normal fluid intake is maintained. Discomfort can be alleviated by maintaining good fluid intake before and during the flight, by using:

• a skin moisturising lotion;


• a saline nasal spray to moisturise the nasal passages; and


• spectacles rather than contact lenses.

Prolonged immobility, particularly when seated, may lead to the pooling of blood in the legs, which in turn may cause swelling, stiffness and discomfort. Circulatory stasis is a predisposing factor for the development of venous thrombi (i.e. blood clots). Most venous thrombi do not cause any symptoms and are reabsorbed without any consequences. In some cases, however, small clot fragments may detach and be carried through the blood stream to the heart and onward into the lungs, causing a pulmonary embolus. This usually occurs only where there is already an extensive clot in the leg and may happen many hours or days after the formation of the clot. This may result in serious consequences, including chest pain, shortness of breath and even sudden death. The risk of developing deep vein thrombosis is very small for travellers unless they have pre-existing additional risk factors for thrombo-embolism, which include:

• a previous history of venous thrombosis


• age of over 40 years


• the use of hormone therapy


• pregnancy


• recent surgery or trauma


• cancer


• genetic blood clotting abnormalities


• chronic venous insufficiency (varicose veins)


• certain cardiovascular conditions

Some researches also suggest that, in addition, there may be a risk from tobacco smoking, obesity and varicose veins. People in these risk groups should seek medical advice before travelling.

The negative effects of prolonged immobility can be reduced by carrying out simple exercises at frequent intervals during the flight. Most airlines provide helpful advice on in-flight exercises to stimulate circulation, hence reducing stiffness, discomfort and fatigue as well as lowering the risk of developing venous thrombosis.

In addition, passengers are advised to:

• Drink adequate fluid, avoid smoking, avoid alcohol and avoid crossing their legs when seated;


• Regularly stand up in your seat area and stretch your arms and legs; and


• Wear loose-fitting, comfortable clothes when travelling.

Compression stockings can help to prevent swelling of the ankles and may improve the return of blood from the lower legs to the rest of the body. The stockings can be purchased from medical and surgical supply companies and will need to be fitted to your leg measurements. You may wish to discuss this with your doctor.

During the flight, move your legs and feet for three to four minutes for every hour that you are seated and walk about the cabin occasionally. Do the in-flight exercises that we recommend below. After arrival at the destination, the effects of the journey can be reduced by gentle exercise to stimulate circulation.

Air travellers very rarely suffer from motion sickness. Travellers susceptible to motion sickness should request for a seat over the wings and/or by a window. If necessary, medication may be taken to prevent motion sickness.

Cabin air contains ample oxygen for healthy passengers. As a result of a reduction in cabin air pressure, the concentration of oxygen in the blood is slightly reduced and may lead to mild hypoxia (i.e. reduced supply of oxygen to the tissues). Passengers with cardiovascular or respiratory disease, or certain disorders of the blood, such as anaemia or sickle cell disease, may not tolerate hypoxia well. The effect of alcohol on the brain is also increased by hypoxia.

Jet lag refers to the disruption of sleep patterns and other circadian rhythms, which result from abrupt changes in time zones. Jet lag may lead to insomnia, indigestion, reduced physical and mental performance and general malaise. The adverse effects of jet lag can be reduced by the use of effective measures. Some of these measures are listed include:

• Be well rested before departure and rest as much as possible during the flight. Ensure that you have as much sleep in every 24 hours when travelling as you would at home and use opportunities for sleep, like naps, effectively. In the case of short trips, it may not always be appropriate to adjust to local time – if in doubt, seek specialist advice.


• Wear loose, comfortable clothing.


• Drink plenty of water and/or juices before and throughout the flight.


• Eat light meals. Limit your consumption of tea, coffee and alcohol both before and during the flight.


• Upon arrival, some may find it beneficial to use short-acting sleeping pills to facilitate the adjustment of sleep patterns. However, use these only under medical supervision and ensure that they have been tried and tested at home before you use them on your trip.


• Stay out in the natural daylight or in brightly lit areas to help adjust more quickly to the time zone of the destination.

• Be well rested before departure and rest as much as possible during the flight. Ensure that you have as much sleep in every 24 hours when travelling as you would at home and use opportunities for sleep, like naps, effectively. In the case of short trips, it may not always be appropriate to adjust to local time – if in doubt, seek specialist advice.


• Wear loose, comfortable clothing.


• Drink plenty of water and/or juices before and throughout the flight.


• Eat light meals. Limit your consumption of tea, coffee and alcohol both before and during the flight.


• Upon arrival, some may find it beneficial to use short-acting sleeping pills to facilitate the adjustment of sleep patterns. However, use these only under medical supervision and ensure that they have been tried and tested at home before you use them on your trip.


• Stay out in the natural daylight or in brightly lit areas to help adjust more quickly to the time zone of the destination.

Travellers who take medication on a strict schedule (e.g. insulin, contraceptive pills) should seek medical advice.

Most airlines that operate international flights have a policy for dealing with medical incidents on board. Cabin crew are trained to recognise and manage a range of in-flight medical emergencies. Airlines usually carry the following emergency equipment and supplies:

• first-aid kits, carried on all aircraft, to be used by the crew;


• a medical kit for the use of doctors or other qualified trained persons in treating in-flight medical emergencies; and


• an automatic external defibrillator, for use by the crew in case of cardiac emergencies.

Cabin crew are trained in the use of first-aid materials and in carrying out first-aid and resuscitation procedures. They are usually also trained to recognise a range of medical conditions which may cause emergencies on board and the appropriate measures to be taken during the flight.

Airlines require medical clearance by the medical department/adviser of the airline if there is an indication that a passenger may be suffering from any disease, physical or mental condition which may:

• become aggravated by the flight environment;


• adversely affect the welfare and comfort of the other passengers and/or crew members;


• be considered a potential hazard to the safety of the aircraft; and


• require medical attention and/or special equipment during the flight.

Airlines reserve the right to refuse to carry passengers with conditions where adverse effects or hazard may result during the flight. When cabin crew suspect that a passenger may be ill, the Commander will be informed and a decision taken on whether the passenger is fit to travel or presents a danger for other passengers or the safety of the aircraft.

Travelling by air is contra-indicated for a number of conditions, which may include the following:

• infants not less than 2 days old and premature babies;


• women in the last 5 weeks of pregnancy (8 weeks for multiple) and until 7 days after delivery;


• people suffering from:


- any serious and acute contagious disease,
- recent myocardial infraction and stroke,
- uncontrolled arterial hypertension of more than 200 mmHg (27 kPa) systolic pressure,
- angina pectoris or chest pain at rest,
- severe chronic respiratory disease, breathlessness at rest or unresolved pneumothorax,
infections of the ear, nose or sinuses; and


• recent surgery or injury where trapped air or gas may be present, especially abdominal trauma and gastro-intestinal surgery, cranio-facial and ocular injuries, eye and brain operations.

1. Raise your arms so that your elbows form a 90-degree angle at chest level. Press the palms of your hands together. Hold the position for six seconds, relax and repeat five to ten times.

2. Sit upright on the edge of the couch or chair. Maintaining this upright posture, lift one foot and then the other alternately, as if you were marching. Bring your knees high and pump your arms simultaneously as you go. Do this exercise for as long as you are comfortable.

3. Sit with one foot flat on the floor close to your chair. Raise the other foot five inches off the floor, first flexing and then pointing your toes. This increases circulation in your lower leg and foot muscles. Repeat up to 20 times. Do the same with the other foot.

4. Tilt your head backwards, arch your back and hold for six seconds. Then bring your chin down to rest on your chest and hold for another six seconds. Repeat this five to ten times.

5. With elbows bent and held just above the armrest, press both elbows against the backrest while keeping your head and chest up and chest in. Breathe normally, hold the contraction for six seconds, then relax. Repeat five times.