The study, conducted by the University of Washington and published in the Journal of the American Academy of Dermatology, shows that 55 percent of upper arm skin cancers, 52 percent of U.S. melanoma cases, and 53 percent of merkel cell carcinomas surface on the left side of the body. The driving connection is given further credence thanks to a 1986 study from Australia that showed the majority of male skin cancers surface on the right side of the body. Australian vehicles are right-hand drive.
While the study suggests that driving with the window down can potentially increase your risk of skin cancer (as is the case with any prolonged sun exposure, for that matter), we do know that rolling the window up provides some protection. Vehicle windows block most UVB rays, which helps mitigate sun exposure. That's good to know, but keeping the windows up 365 days a year is an unreasonable expectation. The open-air experience is part of what makes the freedom of driving so rewarding. Might not be a bad idea to keep a tube of sunscreen handy for those sunny, windows-down days, though.