SHEDDING SOME LIGHT ON UV EXPOSURE
THE GEEKY PART
UV is known as ultraviolet light because its wavelengths are simply shorter than those of the color violet: the shortest wavelengths most of us can see. The UV range itself is divided into two groups, UVA and UVB. Ultraviolet A (UVA) rays are more common on the earth's surface because Ultraviolet B (UVB) rays are most often absorbed by the ozone layer.
If you lived through the '60s, you probably know one part of the UV range as “black-light.” This is what makes some things glow “psychedelically.”
WHAT YOU DON'T SEE MIGHT STILL COOK YOU
But aside from trippy flashbacks, why should you care about UV? Well, it turns out that different wavelengths affect our bodies in different ways. While microwaves (longer than visible light) can literally cook meat, UV energy (shorter than visible light) messes with our cells in other ways.
Skin exposure to UV can lead to suntans, sunburn, or skin cancer (melanoma). Eye exposure can lead to snow blindness or cataracts. The length and intensity of exposure affects risk, and some people—especially those with light colored skin—can be more susceptible to problems.
Most UV light comes from the sun, and where the ozone still exists, gets filtered out in the atmosphere. But besides the stuff that gets through from the sun, workers can be also exposed from man-made sources including welding arcs and special purpose lamps used for groovy effects, CSI-type work, or killing germs.
Ordinary glass will filter some UV light, and special glass will filter all of it, but you won’t be able to tell the difference by looking at the glass.
SO WHAT'S A PERSON TO DO?
The simplest thing to do is to try to avoid the sun between 10am and 4pm (peak sun hours) all year round or stand in the shade and wear a wide-brimmed hat to keep the sun off your face.
Clothing blocks some UV, depending upon the type of fabric and tightness of the weave. Now new standards are evolving to help consumers understand the UV-blocking effectiveness of different materials.
Ultraviolet Protection Factor (UPF) ratings for clothing are an estimation of the effectiveness of the garment at blocking UV rays. The scale is from 15 to 50. A UPF of 50 means that only 1/50th of the UV gets through, so higher numbers are better. And you don't have to wear thick, woolen garments like a Bedouin to get good protection. UPF 50 garments can be thin, light, and airy.
For exposed skin, like your face, sunscreens are the way to go. To block UV, old time mountain climbers used to apply thick, white zinc-oxide creams to their noses. (F.R.E.D. still uses this on formal occasions). Modern sunscreens are clear and actually absorb UV energy. Be sure to use a "broad-spectrum" sunscreen too. These protect from both UVA and UVB rays.
Look to a sunscreen’s Sun Protection Factor (SPF) for guidance on how long a user of that product can stay exposed. For example, an SPF of 10 signifies that a person can stay out 10 times as long as if they had NO sunscreen on. Sunscreen can get absorbed by the skin, worn off by work, or washed away by sweat, so be conservative and follow the instructions on the label.
And don't get creative with the math: applying an SPF of 10 over an SPF of 5 doesn't mean that you will get an effective protection factor of 15 or 50. Buy and use the level you need.
THE EYES HAVE IT
Lastly, protect your eyes with shades. Aside from looking cool and authoritative, quality sunglass can filter out most UV light. Whether they are store-bought, prescription, or safety glasses, buy good ones and be sure they are rated to block at least 99% of both UVA and UVB rays. Why by good ones? Cheap sunglasses can actually cause more harm than wearing none because they cause your pupils to dilate, exposing them to more UV.
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