How boozing leads to air rage

As 20 million of us board planes for our annual summer holiday over the next few weeks, air rage is making the headlines again.

Last week, Hollywood star Rebecca Broussard, mother of Jack Nicholson's two children, was arrested on board a flight from Los Angeles to Heathrow. The captain was forced to make an emergency stop in Canada, allegedly after she exploded in anger when she was refused more champagne. In April, REM guitarist Peter Buck was cleared of going on a drunken rampage during a transatlantic flight.

In both cases, it looks as if alcohol was to blame. Research by the Civil Aviation Authority suggests that 50 per cent of air rage incidents are alcohol-related.

On a long-haul flight, drinking can be exacerbated by a lack of exercise and constant noise. But what does alcohol do to the body when it's travelling at 30,000 feet and 500 miles per hour?

Brain

"One drink in the air equals two on the ground," says Farrol Kahn, director of the Aviation Health Institute. "You reach a high level of oxygen deprivation more quickly." The higher the altitude, the harder it is for oxygen to reach the brain. If the brain has insufficient oxygen, normal thought patterns and behaviour could become disrupted.

With cabin pressure set at 8,000 feet above sea level, most people function perfectly well. But drinking, says Mr Kahn, adds the equivalent of another 4,000 feet, smoking 2,000 feet and taking tranquillisers another 2,000 feet. "That's why some people become disinhibited and join the mile-high club, or become very aggressive," says Kahn.

Heart

For someone with heart disease, flying can already be a stressful event. But adding alcohol could make things worse because it can make the heartbeat irregular. It's thought that the combination of drinking and hypoxia - reduced oxygen levels - may be responsible for "holiday heart", where holidaymakers can fall ill for no obvious reason. "Low oxygen impairs cardiac function," says Professor Timothy Peters, an expert in clinical biochemistry at King's College Hospital. "If there's low oxygen in the blood, you're more likely to get an angina attack."

Blood pressure

Drinking can raise blood pressure and so can the stress of travelling - put the two together and the result is a potentially dangerous effect on the body. "Alcohol stimulates the production of stress hormones, and if you're hanging around waiting for a plane, it can make things worse," says Professor Peters.

Lungs

Alcohol interferes with lung function by causing peripheral blood vessels - such as those in the skin or legs - to dilate. This diverts blood to these areas and away from the lungs, where it delivers vital oxygen supplies. In healthy air passengers, this is unlikely to cause any problems but for those with smokingrelated lung disease, it can result in respiratory failure. "Lots of people with impaired lung function may be able to cope at sea level but not at an altitude of 8,000 feet," says Professor Peters.

Circulation

"Flying long distance can give you swollen ankles and that can be made much worse by drinking alcohol," says Professor Peters. Again, it's to do with the pooling of blood caused by the way alcohol dilates vessels in the leg. As they become more relaxed, they are less able to pump blood back to the heart. The accumulation of blood in the ankles triggers the swelling and may even contribute to the increased risk of deep vein thrombosis - so-called "economy-class syndrome".

Body temperature

The body's thermo-regulation system can be severely disrupted by alcohol. On a plane, where the cabin air is drier than most deserts and stress and noise can also take their toll, the effects are amplified. It's unlikely to be a serious threat to health but can add to discomfort and frustration.

Fluid levels

At least one study suggests dehydration may lead to fainting or heart attacks. Alcohol is a diuretic, which means it flushes water out of the body. Combined with the lack of moisture in cabin air, the result can be a serious drop in fluid levels. "Flying dehydrates you because the moisture in the air is low, when you breathe out you tend to lose more fluid," says Professor Peters. "Alcohol just stimulates this loss of water."

Next week: Get fit to fly