With an ever increasing number of people using air travel, airports around the world are becoming ever more crowded, the check-in queues are getting longer and flight delays are on the increase.

Nevertheless, the cost of flying has dropped in relative terms over recent years and air travel has also made the more remote regions of the world a lot more accessible to ordinary individuals. Flying is also statistically "the safest way to travel".

Airline restrictions on flying

Many airlines will not allow passengers to fly with certain conditions. Regulations may vary so if in doubt seek advice from the medical department of the airline concerned.

Economy Class Syndrome (Deep Vein Thrombosis - DVT)

Much about this condition has been reported recently in the media. Deep Vein Thrombosis (DVT) is a condition in which a clot, or thrombus, typically forms in a deep vein in a leg. People with a DVT may notice pain and swelling in the leg where the clot has formed, though smaller clots may not cause any symptoms. The major problem occurs when a part of the clot breaks off and flows to the lungs. This condition, called a Pulmonary Embolus, can cause severe injury or death.

Sitting still for long periods of time in cramped conditions can lead to swollen ankles and occasionally DVT. This of course is not unique to air travel but the cramped conditions often found in economy class seats especially on long haul flights has given rise to the name "Economy Class Syndrome".

Recent research, however, has found that passengers in any seating class of the aircraft may develop a DVT. Research indicates that any situation where one's activity is limited for long periods - a long automobile drive or train ride, for instance - may contribute to a DVT. For this reason, the term Traveler's Thrombosis is more appropriate.

Dehydration can often put travellers at higher risk. The circulating air in aircraft cabins is kept dry and this can lead to passengers becoming significantly dehydrated. Consumption of alcohol before or during the flight will worsen this. Some passengers may be flying from areas that have a hot and arid climate and may be dehydrated on boarding the plane. Others may be dehydrated as a result of contracting a bout of travellers diarrhoea.

Other risk factors include; age (over 60), previous DVT, varicose veins, recent surgery or injury, pregnancy, oral contraception, hormone replacement medication, cardio-respiratory disease and other chronic illnesses including malignancy.

Those persons with three or more of the above risk factors should discuss additional protective measures with their doctors.

Preventative measures against DVT include:- Regular stretching and mobility exercises and if possible walking around the cabin during the flight. Drinking sufficient fluids to keep the urine pale. Taking a low dose aspirin tablet (75mg) for its anti-adhesive effects on blood platelets. The use of graded compression stockings. These are available at most pharmacies and are marketed specifically for use during long haul flights. Loose-fitting clothing may be beneficial in avoiding constriction of veins. Some recommend taking short naps, instead of long ones, to avoid prolonged inactivity

This condition has been known to doctors for many years. Until recently it was beleived it only affected people of advanced years. It is now known it can strike at any age irrespective of physical fitness. Complications may arise that prove fatal. Anyone who sits in cramped conditions on a long-distance aircraft, coach, train or car is particularly at risk.

Jet Lag

Nowadays it is possible to travel to distant parts of the globe in a matter of hours. This can result in the traveller ending up in a part of the world where time is out of sync. With his or her own "body clock" or Circadian Rhythms which regulate our sleep patterns.

If we travel east or west by more than four time zones (hours) then we will usually be affected. This means that travellers from the UK will be affected when travelling to Asia, Australia, New Zealand, The Pacific Islands, North and South America but will not normally be affected when travelling to Europe, Africa and The Middle East.

In the past when people travelled by sea there was ample time for the body to adjust to the local time but with the advent of modern high speed aircraft the body does not have time to adjust. Hence the term "Jet Lag". It normally takes one day per time zone (hour) for the body to adjust to its new surroundings.

The effects of jet lag are usually tiredness & insomnia but can also include: poor concentration, nausea, vomiting, constipation and general malaise. The effects are made worse by alcohol and hangover.

Westward travel is usually tolerated better than Eastward. Stop-overs on long haul flights may be helpful. Avoiding heavy commitments on the first day after arrival is recommended. When travelling away on vacation the effects may not be so noticeable but on returning home to a normal routine they will be.

Sleeping whilst flying may help to reduce the symptoms of jet lag but long periods of immobility aboard the aircraft can make the traveller more susceptible to DVT.

Some travellers find taking melatonin helpful. It may help the body to adjust its circadian rhythms but its effects are scientifically unproven. It is not readily available in the UK but can also be obtained in some countries such as USA and Hong Kong.

A relaxed flight is important. Avoid travelling when you are already tired and take rest before departure. Remember the actual travelling time will usually be at least twice the actual time spent in the air since it will include travelling to and from and hanging around in airports. Avoid heavy commitments on the first day. Be prepared for tiredness in the evenings and early waking which can last up to 5 or more days. Sleeping tablets will help you to sleep and be correspondingly alert during the next day but they do not speed up adjustment to the new time zone.

Respiratory Infections

There is no evidence that re-circulation of the air in aircraft cabins increases the risk of spreading infections amongst the passengers since very effective filters are used to remove bacteria and viruses.

However, sitting for long periods in close proximity to passengers who are suffering from common colds or influenza may increase the chances of another passenger becoming infected. This is why most airlines discourage passengers with infectious conditions from flying.

Tuberculosis is increasing world-wide and there is a small but real risk of catching the disease during air flights. Transmission has only been recorded in flights lasting over eight hours. The risk is greater when many of the passengers on board are from countries with a high incidence of the disease.

The risk of transmission of TB on a commercial aircraft is low and there is no reason to suspect that the risk of transmission on aircraft is greater than in any other confined space including other forms of public transportation if the duration is the same.


Parasite Infestation

Occasionally head lice and other skin parasites may be passed on through contact with aircraft seats where previous passengers have been infested. It must be stated though, that most airlines carry out thorough cleaning of the cabin and other facilities between flights.

International flights to some countries (including the UK) require the spraying of the aircraft passenger compartment with insecticide when departing from certain locations while the passengers are present, or require periodic applications of a residual insecticide. This practice, called disinsection, is used to prevent the importation of insects such as mosquitoes but this will also have an effect on any other insect parasites present.

Altitude sickness on arrival

Most healthy people who travel rapidly to 3500m above sea level may develop symptoms of acute mountain sickness (AMS) after arrival. People with respiratory or cardiac problems may experience symptoms at even lower levels.

A few airports in the Andes and Himalayas are actually sited above this altitude which can result in symptoms occurring soon after disembarking.

An awareness of the symptoms of AMS would be helpful. Dehydration exacerbated by the dry aircraft cabin atmosphere may worsen symptoms.

Acclimatisation and rest after arrival is recommended since strenuous activity may worsen symptoms.. Further ascent should be avoided until any symptoms have disappeared.

Those persons with pre-existing hypoxic respiratory disease should seek medical advice prior to departure.

Fear of flying

An estimated nine million people in the UK suffer anxiety about flying and may miss out on professional and personal opportunities as a result. Fear may develop from a bad experience - a rough flight, or after a news report of a high jacking or crash.

Panic attacks are common and the sensation is often so frightening that the sufferer may refuse to fly from then on.

Advice for travellers who are afraid of flying Emphasise that flying is safer than road or rail travel in most developed countries. Try distraction by talking with other passengers, watching in-flight films, eating or reading. Tell the cabin crew. Reassurance about strange sounds etc. can help. Visit your doctor prior to travel to assess your general fitness for air travel. Consider taking a tranquilliser before flying but remember, these drugs do not mix well with alcohol.

Air rage

This term describes the psychological or physical violence occurring within an aircraft during flight. It is of particular concern because of the cramped conditions inside an aircraft and the inevitable involvement of cabin crew and other passengers.

There have been several instances where aircraft have had to land prematurely to offload disruptive passengers and taken legal action against those involved.

Air rage may be caused by a combination of events, including delayed flights, exhaustion due to lack of sleep, excessive use of alcohol and the behaviour of fellow passengers. It has recently been recognised that a common cause of air rage is nicotine withdrawal in heavy smokers on long-distance 'no smoking' flights which have now been introduced by many airlines.

Passengers should avoid excessive alcohol consumption and discourage their travelling companions from heavy drinking. Airlines have the right to refuse to carry those who are intoxicated or who have previously caused disruption on a flight.