Activities: Activity 8.2
From Kelly, p. 75
Summer is getting closer. The days are getting longer, and the sun is moving higher across the sky. There are lots of sunny, playful days ahead. But over the years, this has been counterproductive for your skin.
Hidden in all that sunshine is something your eye is incapable of seeing. It’s a part of the sun’s ultraviolet rays, called UVB. It is so damaging that most living things had to develop some kind of protective cover to screen it out. Your skin protects you by absorbing UVB.
Just as in other animals, human skin has some melanin. This is a dark pigmentation that is a good absorber of UVB. Our skin colors vary widely, so some of us are more sensitive to sun than others. Skin with less pigment is more sensitive to the sun’s harmful rays.
You might already know about sunburn. You go to the beach or out for a long, idyllic hike early in the summer. That is when your skin takes a big dose of sun. Later that night, you realize your skin is burned badly — it feels hot and probably hurts. In a few days, the burn will heal and your skin will feel well again.
You might also know about suntan. That’s what happens to many of us when we are exposed to the sun a little at a time. Tanning is the skin’s way of being protective by making more melanin. A suntan looks nice, but by the time you get one, the deeper layers of skin have been damaged. Over time, the skin’s elastic bers gradually lose the stretchiness that keeps your skin tight and smooth.
Though it may happen very gradually, the skin tends to get leathery and wrinkled. Years of exposure to UVB makes you susceptible to skin cancer. Fortunately, we can protect our skin from UVB. One good way is to pick the right time of day to be outside. That way we can use the earth’s atmosphere to screen out UVB more completely.