World Health Organization (WHO) officials are searching for funds to begin a two-year study of economy class syndrome. The condition, also known as deep vein thrombosis (DVT), occurs when potentially deadly blood clots develop in the legs. Officials want to study the link between extended air travel and DVT. Currently, some airlines warn their passengers of the risk of blood clots developing if they sit for long periods of time without exercising their legs.

If blood clots from the leg break loose, they travel through the body and may become lodged in major vital organs, cutting off blood supply. If untreated, the clots can be fatal.

Dozens of deaths have been linked to DVT. Researchers hope to discover why blood clots occur so frequently during long distance flights. By conducting research, the WHO wants to develop better warnings for passengers on extended flights. Currently, some airlines suggest that travelers do basic leg exercises during long flights to prevent clots from forming. However, experts are not certain whether such exercises prevent clots.

In the past three years, at least 30 passengers arriving at London's Heathrow Airport have died from blood clots. Since 1993, 25 similar deaths were recorded at Tokyo's Narita airport.