Skin

24 November 2009

UV rays: FAQs

Ultraviolet (UV) rays are a part of sunlight that is an invisible form of radiation. Here's what you need to know.

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When it comes to protection from the sun, you'll know that it's the UV rays you have to be concerned about. Brush up on the facts with these frequently asked questions, and cut your risk for skin cancer.

Q: What exactly are "ultraviolet rays"?

A: Ultraviolet (UV) rays are a part of sunlight that is an invisible form of radiation. UV rays can penetrate and change the structure of skin cells.

There are three types of UV rays: ultraviolet A (UVA), ultraviolet B (UVB), and ultraviolet C (UVC). UVA is the most abundant source of solar radiation at the earth's surface and penetrates beyond the top layer of human skin. Scientists believe that UVA radiation can cause damage to connective tissue and increase a person's risk for developing skin cancer.

UVB rays are less abundant at the earth's surface than UVA because a significant portion of UVB rays are absorbed by the ozone layer. UVB rays penetrate less deeply into the skin than do UVA rays, but also can be damaging.

UVC radiation is extremely hazardous to skin, but it is completely absorbed by the stratospheric ozone layer and does not reach the surface of the earth.

Q: How can I protect myself from the sun's UV rays?

A: When possible, avoid outdoor activities during midday, when the sun's rays are strongest. This usually means the hours between 10am and 3pm. You can also wear protective clothing, such as a wide-brimmed hat, long-sleeved shirt, and long pants.

For eye protection, wear wraparound sunglasses that provide 100% UV ray protection. And always wear a broad-spectrum (protection against both UVA and UVB rays) sunscreen and lipscreen with at least SPF 15. Remember to reapply as indicated by the manufacturer's directions.

Also, check the sunscreen's expiry date. Sunscreen without an expiry date has a shelf life of no more than three years. Exposure to extreme temperatures can shorten the expiry date or shelf life of sunscreen.

Q: What can excessive exposure to UV rays do to my health?

A: UV exposure appears to be the most important environmental factor in the development of skin cancer and a primary factor in the development of lip cancer.

Although getting some sun exposure can yield a few positive benefits, excessive and unprotected exposure to the sun can result in premature aging and undesirable changes in skin texture. Such exposure has been associated with various types of skin cancer, including melanoma, one of the most serious and deadly forms.

UV rays also have been found to be associated with various eye conditions, such as cataracts.

Read more: Know your skin cm x cm

(Information supplied by the Cancer Association of South Africa, www.cansa.org.za.)

 

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Skin expert

Dr Suretha Kannenberg holds a degree in Medicine and a Masters in Dermatology from the University of Stellenbosch. She is employed as a consultant dermatologist by Stellenbosch University and Tygerberg Academic Hospital, where she is involved in clinical duties and the training of medical students and dermatology residents. Her areas of interest and research include vitiligo, eczema and acne. She also performs limited private practice work in the Northern suburbs of Cape Town in general and cosmetic dermatology.

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