This morning, I got a glimpse of a photo on the news that shocked me. The New England Journal of Medicine reported this case of a 69-year-old man with skin damage on the left side of his face due to repeated sun exposure through the window of his truck. The photo shows a sharp contrast in skin texture between the exposed left side of his face to the less exposed right side of his face. The man was a truck driver for 28 years. The photo reminded me of advice I got from my dermatologist not too long ago. I asked her about some pigmentation that was developing on the left side of my face and not on my right. Her answer: sun exposure through the window of your car. I always assumed there was some protection in my car windows but she told me that damaging rays can still penetrate the side windows. Sun damage to the skin is cumulative and can lead to skin cancers. After our conversation, I found a good article from the Skin Cancer Foundation on "Sun Hazards in Your Car."It provides some details and quotes research about this damaging effect. For example, researchers found a parallel in countries with right side drivers. In those countries, drivers developed more sun damage on the right side of their bodies. Another study showed a higher incidence of skin cancers on the left side of the body than the right in the United States.So, what can you do? Don't do what I did and assume your car windows are protecting you. As the article says, apply sunscreen daily and make sure you reapply it throughout the day. Wear protective clothing and sunglasses. Also, you can get UV-protective film or tint for your car windows, which will screen out a good percentage of harmful rays.