Sun Safety 101
Overexposure to the sun's rays affects people of all ages and all skin types throughout the year. Skin cancer is the most common of all cancers and the number of cases in the United States is on the rise.
According to the American Cancer Society, more than 1 million cases of basal cell or squamous cell cancer will be diagnosed annually. Furthermore, the most serious form of skin cancer, malignant melanoma, is expected to be diagnosed in 55,100 persons in 2004.
UV radiation is the most important environmental factor in the development of skin cancer. This makes skin cancer a largely preventable disease when sun protective practices and behaviors are consistently applied and utilized.
Before you and your family head outdoors, take time to learn more about the types and effects of UV radiation. Also, find out how the UV Outlook Index is calculated. It’s recommended you find out how the sun's rays may affect you and what you can do to protect yourself.
UV Radiation
Any time the sun's ultraviolet (UV) rays are able to reach the earth there is a risk for excessive sun exposure. 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 appears to be the most important environmental factor in the development of skin cancer and has also been associated with various forms of eye damage, such as cataracts.
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 is less abundant at the earth's surface than UVA because a significant portion of UVB is absorbed by the ozone layer. UVB does not penetrate as deep into the skin as UVA does, but, nonetheless, can also be damaging and has been associated with the development of skin cancer.
- 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.
UV Outlook Index
The Weather Channel has developed a current and forecast ultraviolet (UV) index to help you prevent overexposure to the sun's rays. The following risk categories are used to identify the levels of skin-damaging UV radiation:
| 0-2 | Low |
| 3-5 | Moderate |
| 6-7 | High |
| 8-10 | Very High |
| 10+ | Extreme |
The UV index depends directly on the solar elevation above the horizon. On a daily basis the UV index will be higher around local solar noon (11:00 AM to 1:00 PM) depending on the time zone. Clear sky days in the winter will have lower UV index values than clear sky days in the summer due to the higher solar angles in the summer.
Hourly UV Index
The hourly index monitors how observed hourly changes in the sky conditions impact the skin-damaging solar UV radiation. The hourly UV index factors in cloud cover, visibility, and present weather conditions in addition to atmospheric ozone concentration, solar elevation and altitude above sea level.
Forecast UV Outlook Index
The forecast UV index provides a UV forecast for the next ten days, based on the daily maximum UV index that is expected in a given location. The forecast UV index depends on the following meteorological parameters as predicted by atmospheric models: forecast cloud cover and visibility, atmospheric ozone concentration, solar elevation and altitude above sea level.
Sun Protection
The effect of the UV radiation on each individual depends on a number of factors, including:
- skin type
- the time of year
- and the amount of sun exposure the person has recently received
Your skin tone and susceptibility to burning is classified according to the following chart:
| Skin Type | Sunburn and Tanning History |
| I | Always burns, never tans, sensitive to exposure |
| II | Burns easily, tans minimally |
| III | Burns moderately, tans gradually to light brown |
| IV | Burns minimally, always tans well to moderately brown |
| V | Rarely burns, tans profusely to dark |
| VI | Never burns, deeply pigmented, least sensitive |
Even if you have tanned or been burned before, it's never too late to protect your skin. Sunscreens protect your skin from UV rays and are classified according to the Sun Protection Factor (SPF). An SPF 4 blocks out 75% of the burning UV rays while an SPF 15 blocks out 93% of the burning UV rays; an SPF 30 blocks out 97% of the burning UV rays.
Always use sunscreen with a Sun Protection Factor (SPF) of 15 or greater. For best results, apply sunscreen about 30 minutes before going outside to allow it time to bond with your skin. In addition to protecting you from overexposure to sunlight, sunscreens also help to prevent other problems related to sun exposure including aging skin and precancerous growths.
Sun Safety Tips
When possible, avoid outdoor activities during the hours between 10 AM and 4 PM, when the sun's rays are the strongest.
Take the following steps to protect yourself and your family:
- Always wear a broad-spectrum (protection against both UVA and UVB) sunscreen with a Sun Protection Factor (SPF) of 15 or higher.
- Be sure to reapply sunscreen frequently, especially after swimming, perspiring heavily or drying off with a towel.
- Wear a hat with a 4-inch brim all around because it protects areas often exposed to the sun, such as the neck, ears, eyes, forehead, nose and scalp.
- Wear clothing to protect as much skin as possible. Long-sleeved shirts, long pants, or long skirts are the most protective. Dark colors provide more protection than light colors by preventing more UV rays from reaching your skin. A tightly woven fabric provides greater protection than loosely woven fabric.
- To protect your eyes from sun damage, wear sunglasses that block 99 to 100 percent of UVA and UVB radiation.
- Consider wearing cosmetics and lip protectors with an SPF of at least 15 to protect your skin year-round.
- Swimmers should remember to regularly reapply sunscreen. UV rays reflect off water and sand, increasing the intensity of UV radiation and making sun protection especially important.
- Some medications, such as antibiotics, can increase your skin's sensitivity to the sun. Ask your doctor or pharmacist about the medicines you take and learn more about extra precautions.
- Children need extra protection from the sun. One or two blistering sunburns before the age of 18 dramatically increase the risk of skin cancer. Encourage children to play in the shade, wear protective clothing and apply sunscreen regularly.
Source: American Cancer Society