We all know about the effects of too much sun exposure. Unfortunately, most people still link sun exposure only to sunburn and use protection only when planning a full day outside. However, years of daily short sun exposures add up the most. Only 10 minutes of sun a day adds up to over an hour of unprotected sun exposure in just one week. What about commuting or just running errands? While the windshield in most cars is very effective at screening UV, the rest of the windows absorb only a portion of the ultraviolet spectrum. Scientists used to think that the portion of the ultraviolet light transmitted through glass (UVA) was safe. Research continues to uncover the fact that there are some damaging effects of this higher wavelength UVA.

Without radiation (light) from the sun, life on the Earth would cease to exist. Although sunlight is essential to plant and animal life, there are certain portions of this radiation that would be sufficient for the human body in much smaller doses. Solar (sun) radiation is a form of electromagnetic radiation, which exists as waves. The length of one cycle of those waves is called a wavelength. Wavelengths are measured in units of nanometers (nm). A nanometer is one-billionth of a meter, or one thirty-millionth of an inch. Different types of energy are distinguished by their different wavelengths.

Scientists have split the solar energy from the sun into three bands of wavelengths. These three bands are: Ultraviolet or UV (100-400nm), Visible Light (400-780nm) and Near Infrared (780-2400nm). As its name suggests, visible light is the light that the human eye can detect or see. Since people vary in their ability to detect visible light, the borders surrounding the visible-light region are arbitrary. Near-infrared radiation is the part of the sun's rays that bring heat to the earth. You feel infrared radiation when you feel the heat of the sun while outside. Ultraviolet is energy from the sun that we can neither see nor feel, yet these short wavelengths can have a tremendous effect on the human body via the skin.

Although ultraviolet light accounts for only three percent of the total solar spectrum (range of types of light from the sun), it is the most active part of the spectrum for photodamage (damage from light). Photobiologists, scientists who study the effects of light on living things, have divided ultraviolet radiation into three groups of wavelengths: UVC (less than 290nm), UVB (290-320nm) and UVA (320-400nm). All UVC and a portion of the UVB radiation are screened by the earth's ozone layer, in areas where it actually still there. UVB is screened completely by glass and many types of plastic glazing. UVB is most commonly known as the part of the UV spectrum that causes sunburn and is more potent (powerful) than the longer wavelength UVA.

UVA is not screened by glass. Until recently, sunscreens were not effective in the UVA region. Most sunscreens still provide very little UVA protection. Although UVB is more potent, UVA makes up over 90% of the ultraviolet radiation that reaches the earth's surface. The total amount of UV that reaches the earth's surface varies by season, time of day and geography. It is usually highest during summer, at midday and at the equator. Please understand that all ultraviolet light is not the same and that different wavelengths of UV may have varied effects on the skin.

Most people believe that, as we get older, our skin naturally begins to wrinkle and sag. While that is true to an extent, scientists believe that as much as 80% of these signs of aging are, in fact, due to sun exposure. Photoaging of the skin results in wrinkles, coarsening, dryness, loss of skin elasticity and pigment changes. A very important change in the skin occurs in the dermis (leather layer) where sunlight causes the elastin fibers, which should be straight, to become thickened and tangled and eventually progress into a single clump of inelastic material (the process of elastosis). This severe deterioration of the elastin fibers is not seen in sun-protected skin. Testing reveals that UVA radiation goes deeper into the skin and will cause elastosis more deeply in the dermis than UVB radiation.

In addition to wrinkles, many of the pigment changes seen with aging skin are related to sun exposure. "Liver spots," moles and white patches are all usually related to getting too much sun. The effects of ultraviolet exposure are cumulative and may take years to be seen easily at social distances. Because children and teenagers spend so much time out in the sun, it is estimated that as much as 80% of UV-induced photoaging may occur within the first 20 years of life. Additional new research indicates that young skin may be even more susceptible to solar damage than older skin. Babies are especially vulnerable to damage from ultraviolet rays, but special consideration must be given to applying sunscreen agents onto a baby's skin because of absorption. Covering the babies skin with tightly woven cloth is preferable.

1. Minimize sun exposure during the hours of 10:00 a.m. to 2:00 p.m. (11:00 a.m. to 3:00 p.m., daylight saving time) when the sun is strongest. Try to plan your outdoor activities for the early morning or late afternoon.
2. Wear a hat, long-sleeved shirts and long pants when in the sun. Choose tightly woven materials for greater protection from the sun's rays. Unfortunately, T-shirt material usually provides an SPF of only 3. The Rit dye company now makes a laundry additive that will add SPF to clothing in the wash however it alters the texture of the clothes according to some patients undesirably.
3. Apply a sunscreen before every exposure to the sun, and reapply it frequently and liberally, at least every few hours, as long as you stay in the sun. The sunscreen should also always be reapplied after swimming or perspiring heavily, since products differ in their degree of water resistance. We recommend sunscreens with an SPF (sun protection factor) of 15 or more printed on the label.
4. Use a sunscreen during high-altitude activities such as mountain climbing and skiing. At high altitudes, where there is less atmosphere to absorb the sun's rays, your risk of burning is greater. The sun is also stronger near the equator where the sun's rays strike the earth most directly.
5. Do not forget to use your sunscreen on overcast days. The sun's rays can be as damaging to your skin on cloudy, hazy days as they are on sunny days.
6. People at high risk for skin cancer (outdoor workers, fair-skinned, light-eyed individuals and people who have already had skin cancer) should apply sunscreens daily.
7. Photosensitivity, an increased sensitivity to sunlight, is a possible side effect of certain medications and cosmetics and possibly even of birth-control pills. Consult your doctor or pharmacist before going out in the sun, if you are using such products. You may need to take extra precautions.
8. If you develop an allergic reaction to your sunscreen, change sunscreens. One of the many products on the market today will likely be right for you.
9. Beware of reflective surfaces! Sand, snow, concrete and water can reflect more than half the sun's rays onto your skin. Sitting in the shade does not guarantee protection from sunburn or sun damage because reflected rays can still reach your skin.
10. Avoid tanning parlors. The UV light emitted in tanning booths causes sunburn and premature aging, and increases your risk of developing skin cancer. Additionally, the UV wavelength composition isn't even natural and may vary from machine to machine or bulb to bulb.
11. Keep young infants out of the sun. Begin using sunscreens on children at six months of age, allowing only moderate sun exposure. Use wide-brimmed hats and clothing, in addition to sunscreen.
12. Teach children sun protection early. Please remember, sun damage occurs with each unprotected sun exposure and accumulates over the course of a lifetime.