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June 1, 2011

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Careful when catching those rays

SUMMER is time for fun in the sun, but remember to protect your skin from damaging ultraviolet rays by covering up and using a good sunblock. Zhang Qian reports.

Dark tans are out (and dangerous) but a light tan is appealing to many people who consider it attractive and a sign of health and energy.

Still, doctors warn that even light tans that seem to be healthy may not be good for you and especially not good for people who burn easily and are not born to be bronzed. Pale skin is not unhealthy skin, they emphasize.

Most urban Chinese women don't have to be warned about the sun - they want white, smooth, even skin and dread freckles. Accordingly they wear hats, gloves, long sleeves and protect themselves from the sun. Sunblock is a big seller.

Western women are not so careful.

Summer is the time of the brightest, direct sunshine and the strongest ultraviolet rays that can cause melanoma or skin cancer. Regular and long exposure also dries and ages the skin prematurely, causing wrinkles and freckles.

Sunblock is an essential weapon in skin defense, but doctors say it should be chosen carefully, applied at least 20 minutes before exposure and be reapplied frequently as directed. Some people are allergic to ingredients in some sun screens.

Sunblock works by scattering or reflecting rays. Some also absorb high-energy UV rays and releasing lower-energy rays that do not damage the skin. Sun screen is less effective, it screens rather than blocks, allowing more rays to reach the skin.

According to the World Health Organization, around 132,000 cases of melanoma, a potentially deadly skin cancer, were reported worldwide in 2010. More than 2 million other skin cancers are reported worldwide.

Many are caused by overexposure to UV rays, both natural sunlight and man made. The sun emits various UV rays - UVC rays, which are blocked by the atmosphere, and UVB and UVA rays, which cause the most damage. UVB, the summertime sunburn rays, usually damage the outer layer of the skin, the epidermis. UVA rays, once thought to be safe and used in tanning beds, are now known to cause the most skin damage because they penetrate deeply to the dermis and damage collagen and fibers. These rays penetrate glass and clothing and are most responsible for premature skin aging and skin cancer.

UVB is usually most intense from 10am to 2pm and strongest in summer. UVA is constant throughout the year.

Therefore precautions are necessary not only on sunny days, but also on cloudy ones. Many people can get badly sunburned on cloudy days when hey don't see the sun.

"Sensitivity to sunshine differs for different people," says Dr Chen Jie at Yueyang Hospital attached to Shanghai University of Traditional Chinese Medicine. "Most people won't get burned unless they are exposed to strong sunshine for more than an hour, but allergic people may break out in rashes in only 15 minutes and can burn quickly."

People born with dark skin (containing more of the dark pigment melanin) are usually less vulnerable since melanin can help protect skin from the ultraviolet rays. But people who are light-skinned don't have enough melanin to protect their skin. This partially explains the relatively higher rates of skin cancer among Caucasians.


Physical barriers are important, including umbrellas, hats, long-sleeves and trousers, as well as sunblock that protects against UVA rays, as well as UVB.

SPF (Sun Protection Factor) is the common method to measure the effectiveness of sunblock against UVB. SPF 15 is supposed to provide protection for 225 minutes. The protection only increases by 4 percent from SPF 15 to 30, 1 percent from SPF 30 to 40, and even less increase for higher index.

With the discovery of UVA damage, sunblock against UVA has become popular. PPD (Persistent Pigment Darkening) and PA (Protection Against UVA) are commonly used to measure protection against UVA; they are similar to the SPF method.

PA+ indicates effective protection against UVA for about four hours, PA++ for about eight hours, and PA+++ indicates the strongest. Likewise, PPD 2-4 indicates protection for up to four hours, similar to PA+, and so on.

The higher the index, the stronger the protection, theoretically. But creams with higher indices burden the skin more, says Dr Chen. Cream with SPF 15 is usually enough to block most UVB ordinary work days without much direct exposure to sunlight; SPF 30 is recommended for people who spend a lot of time outdoors.

"I recommend creams with physical barriers rather than chemical barriers as they are more stable and less likely to cause irritation," says Dr Chen.

The physical barriers reflect and scatter ultraviolet radiation, while chemical blocks usually absorb radiation and release it in a milder form with less damage to the skin. Chemical block cream when exposed for a long time may cause allergies.

People with acne often believe sunlight is good for the condition, but sunblock is essential for them as UV rays aggravate acne and can leave dark pimples and pigmentation. Physical barrier blocks with good air permeability are best. Sunblock should be removed thoroughly after exposure; cleansing oil is best since it unblocks pores.

Because sunblock needs time to take effect, it should be applied 15 to 30 minutes before going outdoors. It should be reapplied periodically, especially if there is a lot of perspiration and intense physical activity.


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