The front windshield of your car blocks most of the UVA and UVB radiation coming from the sun, but the driver's side window may not be pulling its weight. A recent study found that while the front windshield blocks 94 percent of UVA rays, the driver's side window only blocked 71 percent.
"Multiple studies have demonstrated that individuals spending a large amount of their time driving have an increased risk of skin cancer and UV-induced skin damage on the left side of their body," said Jason E. Hawkes, MD, University of Utah Department of Dermatology. "This damage is primarily due to the UVA light passing through the driver's side window."
Compared to UVB, UVA light has a longer wavelength, which allows it to penetrate into the deeper layers of the skin. The damage caused by UVA light is the primary cause of wrinkling, sagging, premature aging, and even skin cancer.
Due to its shorter wavelength, UVB light is more easily blocked by window glass," Hawkes said. "However, the longer UVA wavelengths require additional protective measures to avoid passing through the glass.
Studies estimate that 74 percent of melanomas appear on the left side, evidence that suggests that the deeper penetrating UVA rays may be contributing to the rise in this more invasive, deadly form of skin cancer.
"While a change in the way cars develop windows would be ideal, in the meantime, individuals should be aware of the detrimental effects of UV light on their skin as a result of long periods of time spent in the driver's seat," Hawkes advised. "When possible, drivers are advised to wear long sleeves and/or apply sunscreen on their arms, hands and face for good measure."
Drivers also should regularly conduct skin self-exams of the whole body and keep an eye out for any new, changing or suspicious spots on their skin. Follow the ABCDEs of skin cancer. And schedule an appointment with a dermatologist if you develop any new or concerning spots.