Economy class syndrome also known as deep venous thrombosis made news a couple of years ago when a British woman died after a long flight from a blood clot. At the time one question left unanswered was how often this occurs.

In a new study, European researchers calculated the risk to be 1 in 4,656. According to Dr. Samuel Z. Goldhaber, a professor of medicine at Harvard Medical School and director of the Venous Thromboembolism Research Group at Brigham and Women's Hospital in Boston:

This risk is a tiny risk compared with the risk of venous thromboembolism from obesity, severe medical illness, cancer, or surgery.

Deep venous thrombosis is a condition in which a blood clot forms in a vein that is deep inside the body. This can occur if a person stays in the same position for prolonged periods; be it on an airplane, in a car, or on a train.

Signs and symptoms to watch out for while traveling include: leg pain, tenderness or swelling in your leg, and changes in skin color in your leg.

While there are no consistently effective preventive measures, you might try:

• Wearing loose and comfortable clothing
• Walking around as much as possible before your flight
• Moving during the flight– rotate your ankles, flex and point your toes, stand up in your row, or walk the aisles at least every hour

Search Healia for more information on economy class syndrome.