Q: Under what types of weather conditions do people need to worry about sun exposure?

A: Any time the sun's ultraviolet (UV) rays are able to reach the earth, people need to worry about excessive sun exposure. Such UV rays, of course, are present on bright and sunny days. UV rays also can penetrate through cloud and haze cover, making cloudy and overcast days dangerous as well. Moreover, UV rays reflect off water, cement, sand and snow. As a result, UV rays can cause skin damage even in the winter when there is snow on the ground.

Relatively speaking, the hours between 10 a.m. and 4 p.m. during daylight savings time (9 a.m. to 3 p.m. during standard time) are the most hazardous for UV exposure in the continental United States. UV radiation also is the greatest during the late spring and early summer in North America. Protection from UV rays, nonetheless, is important all year round, not just during the summer or at the beach.

UV Rays

The ultraviolet (UV) portion of sunlight is an invisible form of radiation that can penetrate and change the structure of skin cells. Exposure to UV rays, moreover, has been associated with the development of serious diseases. In fact, UV exposure appears to be the most important environmental factor in the development of skin cancer. Exposure to UV radiation is also a primary factor in the development of lip cancer. UV rays also have been found to be associated with various forms of eye damage such as cataracts.

Q: What exactly are "ultraviolet rays"?

A: The ultraviolet (UV) portion of sunlight is an invisible form of radiation that 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 now believe that UVA radiation can cause damage to connective tissue and increase a person's risk of developing skin cancer. UVB rays are less abundant at the earth's surface than UVA because a significant portion of UVB is absorbed by the ozone layer. UVB rays penetrate less deeply into the skin than do UVA rays, but, nonetheless, also can be damaging. Lastly, UVC radiation is extremely hazardous to skin but is completely absorbed by the stratospheric ozone layer and does not reach the surface of the earth.

Q: How can people protect themselves from the sun's UV rays?

A: There are a number of ways you can protect yourself:

• When possible, avoid outdoor activities during midday, when the sun's rays are strongest. This usually means the hours between 10 a.m. and 4 p.m.
• As appropriate, wear protective clothing such as a wide-brimmed hat, long-sleeved shirt and long pants.
• Wear sunglasses that provide 100 percent UV ray protection.
• Always wear a broad-spectrum (protection against both UVA and UVB) sunscreen and lipscreen with at least SPF 15
• Remember to reapply as indicated by the manufacturer's directions.

Q: What can excessive exposure to these UV rays do to one's skin?

A: 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 also has been associated with various types of skin cancer including one of the most serious and deadly forms of such cancer -- a form known as melanoma.

UV Index

Q: What is the UV Index?

A: The UV Index, developed by the National Weather Service and the Environmental Protection Agency, provides a forecast of the expected risk of overexposure to UV from the sun and indicates the degree of caution you should take when working, playing or exercising outdoors. The UV Index predicts exposure levels on a zero to 10+ scale, where zero indicates a low risk of overexposure and 10+ means a very high risk. Calculated on a next-day basis for dozens of cities across the U.S. by the National Weather Service, the UV Index takes into account clouds and other local conditions that affect the amount of UV radiation reaching the ground.

Note that the amount of danger posed by the various basic categories of the index are specifically calculated for a person with Type II skin. For a person with type II skin, for example, an Index value of a five or a six represents a moderate possibility of UV exposure.

Tanning and Burning

Q: What does a suntan indicate? Why does the skin tan when exposed to the sun?

A: Although some people believe otherwise, a suntan is not an indicator of good health. In fact, scientists say that the sun exposure one gets while tanning actually can cause damage to the skin. Some physicians consider tanning a response to injury because it appears after the sun's UV rays have killed some cells on contact and damaged others. The penetration of those UV rays to the skin's inner layer is what results in the production of more melanin. That melanin eventually moves toward the outer layers of the skin and becomes visible as a tan.

Q: Not everyone burns or tans in the same manner. Are there ways for classifying different skin types?

A: Whether individuals burn or tan depends on a number of factors, including their skin type, the time of year and the amount of sun exposure they have received recently. The skin's susceptibility to burning can be classified on a five-point scale as outlined in the following table:

Though everyone is at risk for damage as a result of excessive sun exposure, people with skin types I and II are at the highest risk.

Rub It On

Besides protecting you from overexposure to sunlight, sunscreens help to prevent other problems related to sun exposure such as aging skin and precancerous growths. Sunscreens currently come in a variety of forms (such as lotions, gels and sprays) so there are plenty of different options. There are also sunscreens made for specific purposes such as sensitive skin, scalps and babies. Regardless of what type of sunscreen you choose however, be sure that it blocks both UVA and UVB rays and that it has at least SPF 15.

Remember that sunscreen must be reapplied throughout the day according to manufacturer's directions, especially after swimming or exercising.

Q: What does a sunscreen's "SPF" rating mean?

A: Sunscreens are rated according to their effectiveness in offering protection from UV rays and then assigned a Sun Protection Factor (SPF) number. Higher numbers indicate more protection. As a rule of thumb, you always should use a sunscreen with at least SPF 15.

Q: Do sunscreens need to be reapplied during the course of a day?

A: You always should follow manufacturers' directions regarding reapplication, or else you will not get the protection from UV rays that you might think you are getting. Although recently developed sunscreens are more resistant to loss through perspiration and removal by water than previous sunscreens were, they still should be reapplied frequently, especially during peak sun hours or after swimming or exercising.

Q: How do sunscreens work?

A: Most sun protection products work by absorbing, reflecting or scattering the sun's rays. Such products actually contain chemicals that interact with the skin to protect it from UV rays.

Q: Some cosmetic products now claim to protect you from UV rays. Can they?

A: Cosmetics and lip protectors containing some of the same protective chemicals used by sunscreens are now on the market. Not all of these products meet the standard of having at least SPF 15, and as a result, they do not offer sufficient protection by themselves.

Cover up

Clothing that covers your skin protects against the sun's UV rays. A long-sleeved shirt and long pants with a thick weave provide the best protection. If wearing all that clothing isn't practical, at least try to wear a t-shirt or a beach cover-up. Keep in mind, however, that a typical t-shirt actually has an SPF rating substantially lower than the recommended SPF 15. Double-up on protection by using sunscreen with at least SPF 15 (and UVA and UVB protection) and staying in the shade when you can.

Q: What kinds of clothing are the best to protect my skin from UV rays?

A: Loose-fitting clothing made from tightly woven fabric offer the best protection. Moreover, you should try to keep dry because a wet T-shirt offers much less UV protection than a dry one.

Q: Does protective clothing have to be a certain color?

A: Wearing clothing made of tightly woven fabric is always a good idea, regardless of the color. Darker colors, though, may offer even more protection than lighter colors.

Q: It gets so hot here in the summer, there's no way I could be comfortable in long pants and a long-sleeved shirt. What else can I do to protect my skin?

A: Protecting yourself from the sun's UV rays doesn't have to be a major chore. it's just a matter of knowing your options and using them. Wearing at least a dry t-shirt is a good start, but it is not enough if you are going to be outside for more than a few minutes. If you can't wear long pants and a long-sleeved shirt, boost your protection by seeking shade whenever possible and by always wearing sunscreen with at least SPF 15.

Get a Hat

Hats can help shield your skin from the sun's UV rays. For the most protection, look for a hat, with a brim all the way around, that shades your face, ears and back of your neck. If you choose to wear a baseball cap, you also should protect your ears and the back of your neck by wearing other clothing, using sunscreen with at least SPF 15 and when possible, by staying in the shade.

Q: For the best protection, what material should I look for in a hat?

A: A tightly woven fabric such as canvas works best to protect your skin from UV rays. When possible, avoid straw hats with holes that let sunlight through.

Q: Do I need to worry about the color of my hat?

A: The amount of shade offered by a particular hat appears to be its most important prevention characteristic. If a darker hat is an option, though, it may offer even more UV protection.

Q: Are there recommended styles of hats for the best protection?

A: The best way to choose a hat is to look for one that provides shade for all of your head and neck. All head sizes are not created equal. As a result, each person should choose a hat style that offers him or her the maximum coverage.

Grab Shades

Sunglasses protect your eyes from UV rays and reduce the risk of cataracts. They also protect the tender skin around your eyes from sun exposure. As a result, a pair of sunglasses can be an important part of your overall sun protection plan. For maximum protection, look for glasses that block both UVA and UVB rays.

Q: What's the best kind of sunglasses to protect my eyes from UV rays?

A: Sunglasses that block both UVA and UVB offer the best protection. The majority of sunglasses sold in the United States today, regardless of cost, meet this criterion so it should not be difficult to find a pair. Wrap-around lenses work best because they will block UV rays from sneaking in from the side or from behind.

Seek Shade

The sun's UV rays are strongest and do the most damage during mid-day so it's advisable to avoid direct exposure to the sun during that time. That usually means between 10 a.m. and 4 p.m. When you can't avoid the sun, reduce your risk of skin damage and skin cancer by seeking shade under an umbrella, tree or other shelter before -- not after -- you need relief from the sun.

Q: I work outdoors all summer and can't stay in the shade. What can I do to protect my skin?

A: If you can't avoid the sun, you can protect your skin by wearing a wide-brimmed hat, long-sleeved shirt and long pants. You also can wear a sunscreen and lipscreen with at least SPF 15 and UVA and UVB protection. When you can, take your breaks and your lunch in the shade.

Q: If I stay in the shade, should I still use sunscreen and wear a hat?

A: UV rays can reflect off of virtually any surface including sand, snow and concrete -- and can reach you in the shade. Your best bet to protect your skin and lips is to use sunscreen or wear protective clothing when you're outside, even when you're hanging out in the shade.

Centers for Disease Control, 5/00

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