Avoid the health risks of a long flight.

• Position: Air Travel

Although you may think the biggest problem on your eight-hour flight from New York to London is boredom, there are health concerns that can arise from being thousands of feet in the air for extended periods of time. Nurse practitioner Kara Schubart offers tips to avoid the health risks that can occur when you have been seated in the upright and locked position for too long.

Stay hydrated. At higher altitudes, the air is less humid, and air filtered throughout the plane is drier than typically seen on the ground. The air inside the cabin of a plane can have humidity levels of 10% to 20%; typical indoor humidity is 30% to 65%. "Staying hydrated is very important. Avoid caffeinated beverages and alcohol, which can dehydrate you faster."

Dehydration can cause a wide variety of problems, ranging from mild skin discomfort and feeling sluggish to more severe issues, such as difficulty breathing for people who have respiratory conditions like asthma.

Be sure to drink plenty of water during the flight and snack on foods with high water content, such as apples or strawberries. Use non-alcohol-based moisturizers, eye drops, and saline nasal spray to keep your body from feeling the effects of the changed environment.

Stay sanitary. Nothing can ruin a trip like getting sick. Catching a bug 30,000 feet in the air seems inevitable given the cramped spaces and recycled air but, if you take some preventive measures, you should walk off the tarmac healthy and ready to start your vacation.

Keep sanitary wipes in your carry-on luggage so you can clean your armrest or tray tables; get plenty of sleep before your trip; and stay hydrated to keep your immune system in peak condition.

If you are sitting next to a passenger who seems to be contagious, excuse yourself and quietly ask for assistance from an attendant, who can give the passenger a...