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Earth Sense: Ultraviolet radiation can damage cars, tires, skin
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This is the season of strong ultraviolet radiation. It’s not a new thing. Ultraviolet is part of the sunlight that reaches the earth. In simple terms, it’s a color the eye can’t see.

Light arrives in our eyes in three different colors, or “bands.” They are distinguished by their wavelength, traveling through the air just like radio waves do.

All the colors we can perceive are a mix of blue (the shortest), green and red (the longest) wavelengths. The reason why waves like radio, infrared or radar don’t hurt us is that they are much longer than red.

Shorter wave types are more critical. Blue is already marginal because it doesn’t focus well on the retina of the human eye. In the 1970s, “modern” institutional architecture thought it fashionable to paint raw concrete walls in garish primary colors. At Heidelberg University, a staircase was painted with alternating red and blue walls. Due to the focus effect, the walls appeared to be wavering as one climbed the stairs.

Below blue, on the shortwave side of the spectrum, is ultraviolet. We can’t see it, but human skin reacts to it by darkening its pigment. This is known as a sun tan. Overexposure of the skin results in the well-known sunburn. In the extreme, this leads to skin cancers of various types. Some are curable, others deadly.

Ultraviolet also does a nasty job on plastics. When car headlights acquired a protective clear plastic shell, the aftermarket followed up quickly with polishing kits because the plastic turns yellow after just a few months.

Park a car in the same spot every day for a few years, and the side facing the sun will get a lot lighter than the other. While this turned the front of my yellow van white after 8 years, it’s merely a cosmetic effect.

More serious is the job that the sun’s ultraviolet does on the tires. The best quality tires have great road-gripping abilities because soft rubber compounds adhere well to asphalt. If the car or motorcycle isn’t driven much, ultraviolet will begin to destroy the tires in just a few years.

Take a sharp look at the sidewalls and check for tiny cracks. When they get deep and numerous, even if the tread is still good, it’s prudent to replace the tires to avoid a blowout on the highway.

Rudi Kiefer, Ph.D., is a professor of physical science and director of sustainability at Brenau University. His column appears Sundays and at gainesvilletimes.com.
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