A partial rescue plan has been agreed for the first large-scale study of whether passengers on long-haul flights are at increased risk of developing life-threatening blood clots.

Scientists have obtained only around a quarter of the 12 million euros (US$11 million) needed for the project, but they nonetheless aim to launch it this week, while continuing to search for the remaining funds.

The past month has seen a spate of lawsuits against airlines by victims of deep-vein thrombosis (DVT) — 'economy-class syndrome' — and their relatives. Proper scientific data are needed to improve our understanding of the risks involved so that we can offer sound safety advice for air travel, says William Toff, a cardiologist at the University of Leicester and a member of the project team.

The proposed project is far larger than previous studies of the problem. Its scientific protocol — called the WHO Research Initiative on Global Hazards of Travel (WRIGHT) — was approved by the World Health Organisation (WHO) last August.

The International Air Transport Association, which represents the airlines, has welcomed the study — at least in public — and has agreed to help the WHO and the International Civil Aviation Organization with the logistics involved.

Fund-raising is being done by the WHO, but only 2.8 million euros has been raised so far, all from within the European Union. Frits Rosendaal, a researcher at Leiden University in the Netherlands, resigned from the project last month, citing a “lack of confidence in the complete commitment from the WHO”.

Shanthi Mendis, a Geneva-based WHO official involved in project planning, says the WHO is “disappointed” that funding has not materialized. “We expected a more enthusiastic response from governments,” she says. But several DVT researchers blame bureaucracy at the WHO for the lack of uptake.

At a meeting in Geneva last week of the project's scientific committee and its European funders, DVT researchers said that they would try to bypass the WHO and solicit funding directly from governments and other sources. To safeguard the study's independence, airlines will not be asked for money.

The meeting agreed that the first two phases of the study will begin this month. One will examine the role of passenger risk factors, such as alcohol consumption, seating conditions and predisposition to the disease. The second will involve the use of experimental pressurized cabins to determine whether low air pressure during flights contributes to the risks of sitting in cramped conditions for long periods.

In the final, most expensive phase, the study would track the health of passengers on some 200,000 flights. But this phase will begin only when full funding has been obtained. And the prospects for that have worsened following the decision by Australia — the nation that arguably depends most on long-haul flights — to snub the WHO effort and pursue its own study.

“We are all impatiently waiting for the funds, with our troops ready to go,” says Bo Eklof, chief of the Straub Foundation's Vascular Center at the University of Hawaii.