For decades, health experts have known that air travel puts people at a greater risk of developing deadly blood clots in their legs; however, one study suggests that vacation packages offering cheap flight tickets could double that risk.

According to the Centers for Disease Control and Prevention, studies have linked long-distance air travel to pulmonary embolisms caused by deep-leg-vein-thrombosis. More prominent in older and heavier travelers, the condition often occurs when the legs remain stationary for extended periods of time.

The CDC says that flights and train rides lasting longer than four hours double a person's risk of developing this type of blood clot, and the risk remains elevated for approximately 60 days afterwards.

Cheap airfare could increase risk

According to a Dutch study, travelers who had a window seat were at twice the risk of developing a blood clot than those who had an aisle seat. The researchers suggested that this was probably because they were unable to move their legs as much; however, they couldn't say for sure.

In the end, if you've been looking at vacation packages offering cheap flight tickets that choose your seating for you, you may want to invest a little extra in a plan that lets you select an aisle seat. Additionally, health experts suggest that passengers on long flights stand or bend and straighten their legs every so often to minimize risk.

Since overweight people tend to be at a higher risk, heavier travelers may also be well-advised to stick to quick weight loss diets if they know they will be traveling long distances several weeks in advance.

If you have plane tickets placing you in a seat that prevents leg movement, the CDC recommends that you drink plenty of water and avoid alcoholic beverages before and during your flight.