Studies demonstrate that the UV exposure we get through car windows can do a lot of damage—a famous one looked at the (shockingly) accelerated weathering on the left side of the face of a truck driver; another showed an increase in skin cancers on Americans’ left side of the face and left arm. “I see this in my practice—it’s pretty incredible to be treating 10 precancers on one side and zero on the other all because of extra sun exposure,” says dermatologist Ellen Marmur, M.D., an associate clinical professor of dermatology at Icahn School of Medicine at Mount Sinai in New York City.
In fact, one recent study published in JAMA Ophthalmology showed side windows allow an average of 25 percent more UVA rays, the type associated with skin cancer and the visible signs of skin aging, into the car than windshields, which are built in a way that blocks out about 95 percent of UVA. All windows of a car effectively block out UVB rays, the type associated with skin cancer and burns.
Related: Could Frequent Flying Pose a Melanoma Risk?
The derms we spoke to who spend quality time on the road insist on adding UVA-protection films to their car windows (since the law varies by state on how dark you can tint your windows, check drivinglaws.aaa.com). “I have the Llumar Air 80 ceramic window tints, which also reduce heat buildup in the car,” says dermatologist Arielle Kauvar, M.D., a clinical professor of dermatology at New York University School of Medicine, whose commute clocks in at two hours daily.
If their windows don’t have the additional exterior protection, they stash powder sunscreens, like the above-mentioned Colorescience one ($64, colorescience.com), in their glove compartments—it won’t break down in a sweltering car—and apply over any exposed skin before they start the engine. “Don’t forget your hands,” says San Diego dermatologist Kimberly Butterwick, M.D. “Women, especially, get a ton of age spots there—I think they tend to keep their hands at the top of the wheel.”
This article originally appeared in the May 2017 issue of Women’s Health. For more great advice, pick up a copy of the issue on newsstands now!