Dr. Bunn continues, "One study shows that frequent fliers are 3.65 times more likely to develop DVT than non-fliers. A non-profit DVT organization at www.airhealth.org reports that three to five percent of air travelers will develop clots. Yet, it is unclear how big a role flying plays in causing these clots. Whether in the air or in a car, it is good to take a break, stand, and stretch every couple of hours." Also, try to avoid the window seat.
A plane is a sealed metal box with giant engines that burn a ton of fuel, so smoke is a legitimate concern.
According to Captain Bunn, "In most accidents, smoke, not impact, is the problem. In case of a smoky evacuation, count the seat backs to find your way to the exit. If you fly a lot, invest in a smoke mask that guarantees breathable air even in smoky conditions."