The following are some of the Center for Disease Control's Frequently Asked Questions about Sun Exposure and other summertime concerns. See the CDC's website for more answers to your questions.
Sun Exposure
Q: When do I need to protect myself from sun exposure?
A: Protection from sun exposure is important all year round, not just during the summer or at the beach. Any time the sun's ultraviolet (UV) rays are able to reach the earth, you need to protect yourself from excessive sun exposure. UV rays can cause skin damage during any season or temperature. Relatively speaking, the hours between 10 a.m. and 4 p.m. during daylight savings time (9 a.m. - 3 p.m. during standard time) are the most hazardous for UV exposure in the continental United States. UV radiation is the greatest during the late spring and early summer in North America. Remember: UV rays reach you on cloudy and hazy days, as well as bright and sunny days. UV rays will also reflect off any surface like water, cement, sand, and snow.
UV Rays
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 is 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 10 a.m. and 4 p.m. 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 percent 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 expiration date. Sunscreen without an expiration date has a shelf life of no more than three years. Exposure to extreme temperatures can shorten the expiration 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.
UV Index
Q: What is the UV Index?
A: The UV Index was developed by the National Weather Service and the Environmental Protection Agency. It provides a forecast of the expected risk of overexposure to UV rays and indicates the degree of caution you should take when working, playing, or exercising outdoors. The UV Index predicts exposure levels on a 0-10+ scale, where 0 indicates a low risk of overexposure and 10+ means a very high risk of overexposure. Calculated on a next-day basis for dozens of cities across the U.S., the UV Index takes into account clouds and other local conditions that affect the amount of UV radiation reaching the ground. The level of danger calculated for the basic categories of the index are for a person with Type II skin. For a person with type II skin, for example, an Index value of 5 or 6 represents a moderate possibility of UV overexposure. More information about the UV Index is available at the EPA Web site: http://www.epa.gov/sunwise/uvindex.html. You can also call the Environmental Protection Agency (EPA) hotline at 1-800-296-1996 for more information on the UV Index.
Tanning and Burning
Q: What does a suntan indicate? Why does the skin tan when exposed to the sun?
A: The penetration of UV rays to the skin's inner layer results in the production of more melanin. That melanin eventually moves toward the outer layers of the skin and becomes visible as a tan. A suntan is not an indicator of good health. Some physicians consider the skin's tanning a response to injury because it appears after the sun's UV rays have killed some cells and damaged others.
Sunscreen
Q: Does it matter what kind of sunscreen I use?
A: Sunscreens 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 the scalp, sensitive skin, and for use on babies. Regardless of the type of sunscreen you choose, be sure that you use one that blocks both UVA and UVB rays and that it offers at least SPF 15.
Q: What does a sunscreen's SPF rating mean?
A: Sunscreens are assigned a Sun Protection Factor (SPF) number according to their effectiveness in offering protection from UV rays. Higher numbers indicate more protection. As a rule of thumb, you should always use a sunscreen with at least SPF 15.
----------------------------------------------------------------------------------------------------------------------
Source: www.cdc.gov/ChooseYourCover. For answers to more of your questions go to the CDC's website.