Whether you realize it or not, every time you get in your car, you’re fielding ultraviolet A (UV-A) radiation through the windows and windshield. The sun’s UV-A rays are responsible for premature aging and wrinkles, as well as skin cancer and cataracts. Although all the windows in your car offer some protection, not all the windows are created equal — which may result in skin damage you’ve never even thought about, according to a new study published in JAMA Ophthalmology.
According to lead researcher and ophthalmologist Brian Boxer Wachler, MD, he noticed something interesting in one of his patients, which spawned the idea for his study. “I was evaluating a patient with keratoconus and I noticed her age spots on her left cheek,” he tells Yahoo Beauty. “I found many studies that found more skin cancer on the left side of the face compared to the right side of the face. In Australia, where people drive on the left side of the road, it’s just the opposite — there is more skin cancer on the right side of the face.”
Since the UV-A protection of cars in the United States differs across models, Boxer Wachler decided to measure the radiation entering vehicles through the windshield and the driver-side windows in 29 automobiles from 15 automobile manufacturers. The cars dated from 1990 to 2014, with an average make year of 2010.
As it turns out, a car’s windshield seems to block roughly 96 percent of the UV-A radiation while you’re driving, whereas the car’s side windows block only around 71 percent of those damaging rays. Only 14 percent of cars (four out of 29) had side windows that shielded more than 90 percent of UV-A radiation.
Boxer Wachler says that side-window protection was super variable. “There was no relationship between high-end cars and low-end cars for side-window UV protection — in other words, many more-expensive cars had just as poor side-window UV protection as more-affordable cars,” he explains. “We also found tinted windows do not guarantee full UV protection, since a number of tinted windows had low UV protection.”
Boxer Wachler says he hopes this study will “fill in the blank” as to why doctors see more skin cancer and cataracts on the left side of the face in the United States, because of lower UV protection on average in driver-side windows. Interestingly, doctors and researchers have long been noticing that more skin cancers and cataracts tend to appear on the left side of the face — right where a car’s driver would be exposed to more UV-A radiation.
Dermatologist Orit Markowitz, MD, director of Skin Cancer and Pigmented Lesions at Mount Sinai Hospital, has also noticed the trend in left-side skin issues. “Cars are better equipped today than they were years ago to block some of the harmful rays,” she tells Yahoo Beauty. “But there is a clear history of driver versus passenger [skin damage]for many patients, affecting the location of their skin cancers and photo damage.”
We know that UV-A damage is extremely harmful. “These are the rays used in tanning beds, and they’re more linked to aging, wrinkling of the skin, and skin cancer than UV-B,” Markowitz says. “Hence, why medical light therapy is mostly limited to narrow band UV-B. When UV-A rays come in contact with the skin, they start altering DNA, and this alteration can continue years after exposure.”
Boxer Wachler says he hopes automakers recognize UV-A protection as a “potential public safety issue for millions of drivers” in the United States and would recommend better blocking of those harmful rays.
What does this mean for you? Don’t forget that you’re still exposed to dangerous UV-A light through windows — and even ones with UV protection are not catchalls. “It would be prudent to consider having an aftermarket fully UV-blocking clear film put on your car’s side windows to protect you and children in the back seats.” If you want to check your car or home’s UV protection, Boxer Wachler says you can contact his office for a free UV tester.
Lastly, just think of this study as another friendly reminder to always apply sunscreen each morning — well before you hit the road.