They look terrible, make your feet sweat and give you a static shock when you put them on. But from now on everybody will be sporting a pair on their summer holidays.

Research has revealed that wearing flight socks can reduce by 90% the risk of developing deep vein thrombosis, DVT, a potentially fatal condition that affects thousands of people every year.

In a review of research published today, scientists said that the socks, which gently compress the leg from the knee down, encourage blood to flow properly in the legs and prevent it from clotting.

"Airline passengers similar to those in the trials in this review can expect a substantial reduction in their risk of a symptomless DVT if they wear compression stockings," wrote the scientists in the Cochrane Library journal. "Wearing stockings might reduce the incidence of this outcome from a few tens per thousand passengers, to two or three per thousand.

"Passengers who wear stockings will also experience less oedema [an abnormal water buildup] in their legs."

Mike Clarke, director of the Cochrane Centre in Oxford who led the work, said the result had surprised him.

"It was a bigger benefit than I was expecting," he said.

DVT occurs when there is a partial or total blockage of blood vessels by a blood clot. It usually occurs in the deep veins of the legs after long periods of sitting still - as the blood flow in the legs slows down it is more likely to form clots. Dehydration and breathing air of a low humidity can contribute to the condition.

Symptoms include a swollen or painful calf or thigh . If left untreated, the clot could break away and lodge in the lungs or the brain, possibly proving fatal.

A potential link to air travel has earned DVT the nickname "economy class syndrome" by people who believe that prolonged sitting in confined conditions is a big factor in developing the problem.

The flight socks tested in the studies are similar to the compressional bandages worn by patients lying in a bed after an operation - another group of people who are prone to developing DVT.

"The idea is that the stockings put pressure on the calf and that puts pressure on the veins that are deep inside the calf that makes the blood get pumped around. Otherwise the blood goes a bit sludgy and sits there and the clots form," said Professor Clarke.

This improved flow means that the blood in the deep veins gets back to the heart more quickly and is less likely to clot.

Prof Clarke's review was based on an analysis of nine previous trials, which collectively studied 2,800 people.

Half were randomly assigned to wear stockings for a flight lasting seven hours while the other half were not. None of the passengers reported any symptoms of DVT. Even so, they were assessed by doctors to detect any potential blood circulation problems in their legs.

"There was a big difference in symptomless DVT between the two groups, equivalent to a reduction in the risk from a few tens per thousand passengers to two or three per thousand," reported the researchers.

Prof Clarke said that his group might continue to look at how best to prevent DVT. "There are some trials being done on shorter duration flying and there's also some work being done on people sitting on buses for long journeys.

"We may well expand the review to have a look at those sorts of issues. We may look at compression stockings for short flights or non-flying travel."

The next phase of the research could also look at how tight flight socks should be for best performance and how they compare to other methods of avoiding DVT.

Approximately 8,000 people in the UK are diagnosed with deep vein thrombosis every year, but many more probably get blood clots in their legs without any symptoms.

Prof Clarke said that while the new research unequivocally recommends wearing flight socks as a way to avoid DVT, he said there are other methods available for long-haul flyers.

"Anything that gets the blood circulating - walking around, calf exercises, wiggling your ankles," he said.

"They're all designed to get the blood flowing in the deep vein of the calf and of the lower leg and that's the standard advice. Drink lots of fluid so that you don't dehydrate."

What is DVT?

Deep vein thrombosis is a blood clot occuring in the legs because of a slow-down in circulation. Often associated with passengers on long-haul air flights, the condition is caused when people sit still for hours at a time.

Compressional bandages work by applying a pressure to the leg, particularly around the ankle. This pressure encourages blood to flow from the veins at the surface of the skin to the veins in the core of the leg, speeding its movement and reducing the chances of it stagnating anywhere. This, in turn, reduces the chances of blood clots developing.