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  Health

Healthy Geezer

 The Healthy Geezer

—Fred Cicetti

Q: There are lots of sunblocks out there with SPF numbers on them. What exactly do these numbers mean?

A: [Sun exposure is an extensive and important subject that is worth two columns. This is the first one.]

Sunblocks—or sunscreens—work to prevent the damage of ultraviolet (UV) rays, an invisible component of sunlight. There are three types of UV rays: UVA, UVB, and UVC.

UVA is the most abundant of the three ultraviolet rays at the earth’s surface. These rays penetrate through the outer skin. Many of the UVB rays are absorbed by the stratospheric ozone layer, so there aren’t as many of these at the earth’s surface as the UVA rays. UVB rays don’t penetrate as far as UVA rays but are still harmful. UVC radiation is extremely hazardous to skin, but it is completely absorbed by the ozone layer.

Sunburn and suntan are signs of skin damage. Suntans appear after the sun’s rays have already killed some cells and damaged others. UV rays do more harm than damaging skin. They can also cause cataracts, wrinkles, age spots, and skin cancer.

Sunscreens are given SPF (Sun Protection Factor) ratings that tell you how well they protect you from damaging rays from the sun. The SPF ratings can be as low as 2 and as high as 100+.

Here’s how the ratings work: If you apply a sunscreen rated at SPF 2, you will double the time it takes for your skin to burn. A sunscreen rated at SPF 15 will multiply the burning time by fifteen.

Dermatologists strongly recommend using a broad-spectrum (UVA and UVB protection) sunscreen with an SPF of fifteen or greater year-round for all skin types.

The SPF number indicates the screening ability for UVB rays only. Research is being done to establish a system to measure UVA protection.

There is a point of diminishing returns with sunscreens. Here’s how it goes:

A sunscreen with an SPF of 2 screens 50 percent of UVB rays.
A sunscreen with an SPF of 15 screens 93 percent of UVB rays.
A sunscreen with an SPF of 30 screens 97 percent of UVB rays.
A sunscreen with an SPF of 50 blocks 98 percent of UVB rays.
A sunscreen with an SPF of 100+ blocks 99 percent of UVB rays.

Not applying enough sunscreen can seriously reduce your protection. You should use an ounce—about a palmful—on your body to gain the full protection indicated by the SPF on the product. Also, dermatologists advise reapplication every two hours or after swimming or sweating.

It seems logical that, if you use half the required sunscreen, you will get only half the protection, but that doesn’t seem to be true. A study in the British Journal of Dermatology found that you get the protection of only the square root of the SPF. So, in theory, if you use a half ounce of sunscreen rated at sixty-four, you won’t get the protection of an SPF 32, but only the protection of an SPF 8.

In addition to applying a sunscreen, you should protect yourself by avoiding the sun between 10:00 a.m. and 4:00 p.m., wearing protective clothing and wraparound sunglasses, avoiding sunlamps and tanning beds, and checking your skin regularly for changes in the size, shape, color, or feel of birthmarks, moles, and spots.

All About Sun Exposure:

Ultraviolet (UV) rays, an invisible component of sunlight, can cause skin damage, cataracts, wrinkles, age spots, and skin cancer. These rays also impair the skin’s immune system.

UV rays can hurt you on cloudy as well as sunny days. UV rays also bounce off surfaces of the ocean, sand, snow, and cement.

One of the surest ways to reduce your exposure to UV rays is to stay out of the sun when it is the strongest. Those times in North America are between 10:00 a.m. and 4:00 p.m. in the late spring and early summer.

Other ways to protect yourself are to wear protective clothing, such as a wide-brimmed hat, long-sleeved shirt, and long pants. You should use a sunscreen rated at SPF 15 or more. Eye doctors recommend wraparound sunglasses that provide one hundred percent UV ray protection.

You should also pay attention to the UV Index developed by the National Weather Service and the Environmental Protection Agency. This index assesses risk of overexposure to UV rays.

The UV Index is calculated daily and is reported by the press. It can be found at: http://www.epa.gov/sunwise/uvindex.html, where you can plug in your own zip code to find out the index rating in your area.

The following are the index levels:

2 or less: Low danger for the average person
3 to 5: Moderate risk of harm
6 to 7: High risk of harm.
8 to 10: Very high risk of harm.
11+: Extreme risk of harm.

It is possible to go outside when the UV Index is eleven or higher, but you must be sure to take every step possible to protect yourself—sunscreen, hats, long sleeves, sunglasses, the works.

Not everyone reacts to the sun in the same way. The level of danger calculated for the basic categories of the UV Index are for a person with Type II skin. The following are the skin types:

I—Always burns, never tans, sensitive to sun exposure
II—Burns easily, tans minimally
III—Burns moderately, tans gradually to light brown
IV—Burns minimally, always tans well to moderately brown
V—Rarely burns, tans profusely to dark
VI—Never burns, deeply pigmented, least sensitive

What Is a Suntan?

When UV rays penetrate the skin’s inner layer they generate the production of melanin—a dark pigment. The melanin eventually moves toward the outer layers of the skin and becomes visible as a tan. Every time you tan, you damage your skin and this damage accumulates over time.

There is no safe tan. What some call a base tan may actually increase the chances you’ll get a burn, because you’re likely to stay out longer without properly protecting your skin.

You should stay away from tanning beds and sunlamps because they emit UV rays that can cause serious long-term skin damage. The amount of radiation produced during indoor tanning is similar to the sun’s production and in some cases may be greater.

Many tanning salons are unregulated. They allow customers access to tanning beds without supervision or eye protection.

 

     

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