The Ultraviolet Index

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New SunWise School Program

A new fact sheet explains EPA's new SunWise School Program to educate teachers and students about how to protect themselves from overexposure to the sun.

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Did 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.

Several flyers explain the UV Index and steps you can take to minimize the risks from overexposure to the sun's rays. Each is available for reading online and downloading.
US Environmental Protection Agency

What is the UV Index?

Some exposure to sunlight can be enjoyable; however, too much could be dangerous. Overexposure to the sunís ultraviolet (UV) radiation can cause immediate effects such as sunburn and long-term problems such as skin cancer and cataracts. Developed by the National Weather Service and the U.S. Environmental Protection Agency (EPA), the Ultraviolet (UV) Index (Link Outside EPA) provides important information to help you plan your outdoor activities to prevent overexposure to the sunís rays.

The UV Index provides a daily forecast of the expected risk of overexposure to the sun. The Index predicts UV intensity levels on a scale of 0 to 10+, where 0 indicates a minimal risk of overexposure and 10+ means a very high risk. Calculated on a next-day basis for dozens of cities across the United States, the UV Index takes into account clouds and other local conditions that affect the amount of UV radiation reaching the ground in different parts of the country.

 

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UV Index NumberExposure Level
0 to 2Minimal
3 to 4Low
5 to 6Moderate
7 to 9High
10+Very High

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By taking a few simple precautions, you can greatly reduce your risk of sun-related illnesses. To be Be Sun Wise!, consider the following steps:

-- Limit your time in the sun between 10 a.m. and 4 p.m.
-- Whenever possible, seek shade.
-- Use a broad spectrum sunscreen with an SPF of at least 15.
-- Wear a wide-brimmed hat and if possible, tightly woven, full-length clothing.
-- Wear UV-protective sunglasses.
-- Avoid sunlamps and tanning salons.
-- Watch for the UV Index daily.

While you should always take precautions against overexposure to the sun, please take special care to adopt the safeguards when the UV Index predicts levels of moderate or above. Watch for UV Index reports in your local newspapers and on television, and remember to be SunWise! For more information, call EPAís Stratospheric Ozone Information Hotline at 800 296-1996.

 

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UV Index listings (Link Outside EPA)
Both a text bulletin and a national map are available from NOAA. In addition, the site provides an archive of past Index listings, graphs of yearly values for each city, information about UV radiation, and several related links.

 

The Sun, UV, and You: A Guide to SunWise Behavior
This brochure includes basic information about ozone depletion, ultraviolet radiation, and simple steps you can take to protect yourself from the sun.

 

Stay Healthy in the Sun
This brochure includes information about the UV Index, health effects of ultraviolet radiation, as well as simple steps that broadcast meteorologists can recommend to viewers to prevent overexposure to the sun. The document will also be of interest to other readers, since it has a focus on basic sun-protection tips.

 

What is the Ultraviolet (UV) Index?
A brief description of the UV Index and the meaning of each value, from 0-10+.

 

Action Steps for Sun Protection
Specific measures to protect yourself from UV radiation.

 

Health Effects of Overexposure to the Sun
A detailed explanation of health effects linked to to UV exposure, including skin cancer, other skin problems, cataracts, and immune system suppression.

 

UV Index: What You Need to Know
This general information brochure summarizes the other fact sheets.

 

UV Index: How Is It Calculated?
This fact sheet describes the creation of the daily UV Index.

 

UV Radiation
This fact sheet explains UV Radiation.

 

Ozone Depletion
This fact sheet explains the relationship between ozone depletion and UV radiation.

 

UV Crossword Puzzle
If your browser can use javascript, you can try your hand at filling in the puzzle on your screen!

 

Sports Teams and the UV Index
EPA is working with the following teams. During games, each team displays the UV Index on their giant screens along with messages to help fans protect themselves from overexposure to the sun. (The web sites below don't have UV Index information; they simply contain general information about each team.) bulletOakland A's [drawing of Oakland's mascot] bulletSan Francisco Giants [drawing of San Francisco's mascot] bulletSan Diego Padres

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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.

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Links to Other Information

UV Index (including other countries' UV Indices)
Health Effects of Ozone Depletion

UV Index: What You Need To Know

Do 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.

 

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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
0-2.......................Minimal
3-4.......................Low
5-6.......................Moderate
7-9.......................High
10+.......................Very High

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.

 

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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.

 

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What are Proper Precautions?

Preventing Skin Cancer

Skin 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 Damage

Because 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

 

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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.

 

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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!

 

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The Following Organizations Collaborated to Bring This Message To You

National 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)

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Need More Information?

For more information on the UV index, 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, FAX (301) 530-8910.

UV Radiation

The 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 atmosphereís 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
-- Cataracts
-- 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.

 

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Types of UV Radiation

Scientists classify UV radiation into three types or bandsóUVA, 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 Earthís surface.

 

UVC: Completely absorbed by the ozone layer and oxygen.

UVA and UVB that reach the Earthís surface contribute to the serious health effects listed above.

 

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UV Levels Depend on a Number of Factors

The level of UV radiation that reaches the Earthís 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 Ozone

The ozone layer absorbs most of the sunís 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 Day

The sun is at its highest in the sky around noon. At this time, the sunís 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 sunís rays pass through the atmosphere at an angle and their intensity is greatly reduced.

 

Time of Year

The sunís angle varies with the seasons, causing the intensity of UV rays to change. UV intensity tends to be highest during the summer months.

 

Latitude

The 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.

 

Altitude

UV 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 Conditions

Cloud cover reduces UV levels, but not completely. Depending on the thickness of the cloud cover, it is possible to burnóand increase your risk of long-term skin and eye damageóon a cloudy summer day, even if it does not feel very warm.

 

Reflection

Some 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.

 

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EPAís SunWise School Program

In 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.