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Need More Information?For more information on the UV index, or to request paper copies of any of the UV Index flyers, please call:
EPA Stratospheric Ozone Hotline:(800) 296-1996 The National Weather Service: (301) 713-0622 Medical and health organizations interested in this project, please contact the National Association of Physicians for the Environment (NAPE), FAX (301) 530-8910.
Links to Other Information UV Index (including other countries' UV Indices)
Health Effects of Ozone Depletion
UV Index: What You Need To KnowDo you know that a few simple precautions can help protect you and your children from skin cancer and serious eye injury?
While some exposure to sunlight is necessary, too much can be dangerous, causing immediate effects like blistering sunburns and longer-term problems like skin cancer and cataracts. Overexposure also causes wrinkling and aging of the skin, and scientists are concerned that UV may even impair the human immune system.
The Ultraviolet (UV) Index provides important information to help you plan your outdoor activities in ways that prevent overexposure to the sun's rays. Developed by the National Weather Service (NWS) and the Environmental Protection Agency (EPA), the UV Index is issued daily as part of a national project.
What is the UV Index?The UV Index describes the next day's likely levels of exposure to UV rays. The Index predicts UV levels on a 0-10+ scale in the following way:
Index Number...........Exposure Level
While you should always take precautions against overexposure, you should take special care to adopt the safeguards recommended below when the UV Index predicts exposure levels of moderate or above.
This UV Index is NOT intended for use by seriously sun-sensitive individuals (some medications cause serious sun-sensitivity, as do some diseases, such as Lupus Erythematosus). Consult your doctor about additional precautions you may need to take.
How Much UV Am I Being Exposed To?UV exposure depends on many things. It varies with the time of day or season of year you are outdoors, latitude and with altitude. Although clouds do not eliminate exposure, they partially screen UV rays. By contrast, water, sand and snow all reflect UV rays, increasing exposure. Finally, people who work or play outdoors for long periods are at greater risk. The UV Index calculation takes altitude and cloud cover into account.
What are Proper Precautions?
Preventing Skin CancerSkin cancer is rising in incidence faster than any other form of cancer. Over 1 million new cases of skin cancer are likely to be diagnosed in the U.S. this year. Protecting children is especially important, since early exposures will influence risks of later skin cancers. Doctors* recommend the following to reduce the risk of skin cancer:
- Minimize sun exposure at midday (10:00 a.m. to 4:00 p.m.).
- Apply a sunscreen with SPF-15 or higher to all exposed areas sufficiently for protection, especially after swimming, perspiring or sunbathing, even on cloudy days.
- Reapply your sunscreen every 2 hours.
- Wear clothing that covers your body and shades your face and neck.
- Avoid unnecessary exposure to radiation from sunlamps or tanning parlors.
- Protect children by keeping them from excessive sun during the hours of strongest sunlight and by applying sunscreen liberally and frequently to children older than 6 months of age.
* The American Academy of Dermatology and the Skin Cancer Foundation
Preventing Eye DamageBecause UV rays can cause cataracts and other serious eye conditions, doctors* recommend that you wear sunglasses that absorb 99-100 percent of the full UV spectrum when outdoors in bright sun. Because there is now no uniform labeling of sunglasses, read labels carefully. Be careful of buying sunglasses that "block harmful UV" without saying how much. Wear a hat with a wide brim to protect against UV exposure, and if you wear sunglasses, too, you provide even more protection for your eyes. Parents whose children will not wear sunglasses can still help protect their children's eyes by making sure they wear a hat with a wide brim.
* Prevent Blindness America, the American Optometric Association, and the American Academy of Ophthalmology
What Role Does Ozone Layer Depletion Play?The stratospheric ozone layer shields the earth from the sun's harmful ultraviolet rays. It is well-established that decreases in the stratospheric ozone far above us can lead to increases in UV at the surface. Ozone levels change from day to day and place to place. Long-term decreases in the average amount of ozone have been measured over the past decade. A better monitoring network is necessary to demonstrate whether there has been a corresponding change in UV radiation in the U.S. Future levels of ozone and UV will depend upon a combination of natural and manmade factors, including CFCs. Experts agree that increased exposure to harmful rays can contribute to long-term increases in skin cancer and cataracts, and harm animals and plants. Current rising rates of skin cancers are likely related to the increasing emphasis on outdoor leisure and work in our society. Whatever the sources of risk, it is important to protect yourself and your family from overexposure to harmful UV rays.
Be Sun Wise!Listen to the UV Index reports. Take common sense precautions to avoid overexposure to the sun's ultraviolet rays. Take special care with children, since they spend more time outdoors than adults and can burn more quickly. The simple actions listed above can reduce your risks of developing UV-related skin cancers and cataracts. Take the hurt out of fun in the sun!
The Following Organizations Collaborated to Bring This Message To YouNational Association of Physicians for the Environment
American Medical Association
Wilderness Medical Society
American Skin Association
American Academy of Dermatology
American Academy of Otolaryngology - Head and Neck Surgery Inc.
American Academy of Ophthalmology
American Academy of Optometry
American Society for Head and Neck Surgery
American Optometric Association
American Society of Plastic and Reconstructive Surgeons
Coalition of Patient Advocates for Skin Disease Research
Society for Investigative Dermatology
Skin Cancer Foundation
Friends of the Earth
National Medical Association
Lupus Foundation of America, Inc.
Ozone Action, Inc.
Alliance for Environmental Education
Association of University Environmental Health Sciences Centers
Prevent Blindness America
Save Our Sky
North American Association for Environmental Education
NAPE National Office for the Protection of Biodiversity (Galveston, TX)
National Association 0f County & City Health Officials (NACCHO)
Environmental Alliance for Senior Involvement (EASI)
Association of State & Territorial Health Organizations (ASTHO)
Need More Information?For more information on the UV index, please call:
EPA Stratospheric Ozone Hotline:
The National Weather Service:
(301) 713-0622Medical and health organizations interested in this project, please contact the National Association of Physicians for the Environment, FAX (301) 530-8910.
UV RadiationThe sun radiates energy over a broad spectrum of wavelengths. Ultraviolet (UV) radiation, which has a shorter wavelength than either visible blue or violet light, is responsible for sunburn and other adverse health effects. Fortunately for life on Earth, our atmosphere's stratospheric ozone layer shields us from most UV radiation. What gets through the ozone layer, however, can cause the following problems, particularly for people who spend substantial time outdoors:
-- Skin cancer
-- Suppression of the immune system
-- Premature aging of the skin
Because of these serious health effects, you should limit your exposure to UV radiation and protect yourself when outdoors.
Types of UV RadiationScientists classify UV radiation into three types or bands-UVA, UVB, and UVC. The stratospheric ozone layer absorbs some, but not all, of these types of UV radiation:
- UVA: Not absorbed by the ozone layer.
- UVB: Mostly absorbed by the ozone layer, but some does reach the Earth's surface.
- UVC: Completely absorbed by the ozone layer and oxygen.
UVA and UVB that reach the Earth's surface contribute to the serious health effects listed above.
UV Levels Depend on a Number of FactorsThe level of UV radiation that reaches the Earth's surface can vary, depending on a variety of factors. Each of the following factors can increase your risk of UV radiation overexposure and its consequent health effects.
Stratospheric OzoneThe ozone layer absorbs most of the sun's UV rays, but the amount of absorp-tion varies depending on the time of year and other natural phenomena. That absorption also has decreased, as the ozone layer has thinned due to the release of ozone-depleting substances that have been widely used in industry.
Time of DayThe sun is at its highest in the sky around noon. At this time, the sun's rays have the least distance to travel through the atmosphere and UVB levels are at their highest. In the early morning and late afternoon, the sun's rays pass through the atmosphere at an angle and their intensity is greatly reduced.
Time of YearThe sun's angle varies with the seasons, causing the intensity of UV rays to change. UV intensity tends to be highest during the summer months.
LatitudeThe sun's rays are strongest at the equator, where the sun is most directly overhead and UV rays must travel the least distance through the atmosphere. Ozone also is naturally thinner in the tropics compared to the mid- and high-latitudes, so there is less ozone to absorb the UV radiation as it passes through the atmosphere. At higher latitudes the sun is lower in the sky, so UV rays must travel a greater distance through ozone-rich portions of the atmosphere and, in turn, expose those latitudes to less UV radiation.
AltitudeUV intensity increases with altitude because there is less atmosphere to absorb the damaging rays. Thus, when you go to higher altitudes, your risk of overexposure increases.
Weather ConditionsCloud cover reduces UV levels, but not completely. Depending on the thickness of the cloud cover, it is possible to burn-and increase your risk of long-term skin and eye damage-on a cloudy summer day, even if it does not feel very warm.
ReflectionSome surfaces, such as snow, sand, grass, or water can reflect much of the UV radiation that reaches them. Because of this reflection, UV intensity can be deceptively high even in shaded areas.
EPA's SunWise School ProgramIn response to the serious public health threat posed by exposure to increased UV levels, the U.S. Environmental Protection Agency (EPA) is working with schools and communities across the nation through the SunWise School Program. SunWise aims to teach children in elementary school and their care-givers how to protect themselves from overexposure to the sun.