DVT victim Emma Christoffersen

Among British travellers who have died after long-haul flights, are several Welsh people including 28-year-old Emma Christoffersen, from Newport in south Wales, who died from a blood clot after flying from Australia to Britain in October 2000.

Last month Vale of Glamorgan MP John Smith helped persuade Sven Goran-Eriksson to get the England footballers to wear special stockings - which may help prevent the condition - on their flight to the World Cup Finals in Korea and Japan.

The research programme aims to identify which travellers are most at risk from DVT, which has been dubbed 'economy class syndrome'.

Factors such as past history of thrombosis, use of oral contraceptives and genetic links are among the areas to be studied.

MP John Smith has campaigned for action

The study will also look at the effects of alcohol consumption, leg exercises and compression stockings, as well as low cabin pressure and oxygen levels on flights.

The research also intends to offer guidance to travellers.

The European Commission is expected to provide additional funding, with preliminary results available within a year.

"The UK government and the European Commission have taken a clear lead in addressing this important public health issue," said Professor Fred Paccaud, chairman of WHO's scientific executive committee.

Fatal risk

More than 40 long haul airline passengers are known to have died from DVT clots.

Among them are Ms Christoffersen, Susan Mavir-Ross, from Llay in Wrexham, Thomas Lamb, from Cardiff, and policeman John Thomas from Cowbridge, south Wales.

Medical research has shown that clots develop in blood vessels deep in the legs when circulation slows.

The clots can prove fatal if they break off and are carried to the lungs, blocking the flow of blood.

Although claims have repeatedly been made linking DVT and air travel, there is no conclusive proof of the link.

John Smith MP has put himself at the forefront of the campaign to get the risks acknowledged.

He chairs an all-party parliamentary group set up to investigate the causes of flight-related DVT.