For most people, car safety means seat belts and airbags. But there's another important way to stay safe on the road, and that's by protecting your skin from the sun.A study in the Journal of the American Academy of Dermatology revealed that nearly 53 percent of skin cancers in the United States occur on the left, or drivers' side of the body. If you're one of the approximately 208 million licensed drivers in the U.S., take heed: "The increase in left-sided skin cancers may be from the UV (ultraviolet) exposure we get when driving a car," said Susan T. Butler, MD, coauthor of the study.Here's how to protect your skin when you're in a car:Treat your vehicle to window filmThe sun's ultraviolet radiation is associated with most cases of skin cancer, which will affect one in five Americans over a lifetime. UV radiation reaches us in the form of shortwave UVB and long-wave UVA rays, but glass blocks only UVB effectively. Although car windshields are partially treated to filter out UVA, the side windows let in about 63 percent of the sun's UVA radiation. Rear windows are also unprotected, leaving back seat passengers exposed. There is, however, a solution. Transparent window film screens out almost 100 percent of UVB and UVA without reducing visibility, and is available in all 50 states. If you have window film installed, remember that it protects you only when the windows are closed.Keep sunscreen in the carA sunscreen should be on hand for quick reapplication during long drives,. The Skin Cancer Foundation recommends reapplying every two hours. Look for one with an SPF of 15+ and some combination of the following UVA-blocking ingredients: avobenzone, ecamsule, oxybenzone, titanium dioxide, and zinc oxide.Skip the sunroof, skip the convertibleDrivers' heads and necks receive the most UV exposure, so it's no surprise that Butler's team found over 82 percent of skin cancers on the patients' heads or necks. A solid, closed roof is your best bet. If you have a sunroof or a convertible top, wear a hat, preferably a wide-brimmed one (three inches or greater all around). At the very least, be sure to apply sunscreen to exposed areas of the face, neck, and scalp.The second most common area for skin cancers was the arm, so, in addition to applying sunscreen, avoid propping your elbow up on the open window while you drive-keep both arms inside the car, and your hands on the wheel. Long-sleeved shirts are also a great sun-protective option.Keep a hat in the car, along with your sunscreen and UV-blocking sunglasses, and you'll have a sun protection travel kit to see you safely to your destination.Source: The Skin Cancer Foundation: skincancer.org.