The World Health Organization (WHO) has launched an investigation into the so-called "economy class syndrome," an illness linked to long airplane flights. The WHO study will cost approximately $11 million and will help to formulate strategies designed to prevent the syndrome, also known as deep vein thrombosis (DVT). Recently, WHO advised passengers to perform mild exercise, drink plenty of fluids, avoid alcoholic beverages, and wear comfortable clothing during long flights. It is hoped that such precautions will help prevent the sometimes deadly blood clots associated with the condition.