[CAR IDLING]

Y: Don, get in the car, we have a long trip ahead.

D: Hang on, Yael, I'm putting on some sunscreen.

Y: Why do you need sunscreen? We're not traveling in a convertible.

D: I know, but I still don't want to get too much exposure to the sun. You know that can      be dangerous.

Y: Yes, but we're not going to be outside, and we're riding in an air-conditioned car.

D: Yeah, but it has windows doesn't it?

Y: Of course it does, but you can't get sunburned through a car window because the      glass blocks the ultraviolet rays that burn.

D: True, but that's only part of the story. Glass blocks UV-B rays, and those are the      ones that cause sunburn. However, unless it's specially coated or tinted, glass does      not block UV-A rays, and those are the rays that penetrate deeper and can cause      skin damage, possibly even skin cancer. Since you don't burn through the glass you      don't realize anything is going on. In short, you don't get burned, but the UV-A rays      damage your skin without your knowing it for a long time. In fact, some specialists      advise you to wear sunscreen if you're going to be driving in most of North America      for more than about twenty minutes, and even less than twenty in the southern states.

Y: Wow! You drive, and I'll slather on some SPF-30.

D: Good idea. And make sure it blocks both UV-A AND UV-B for maximum      protection.  

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