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Sun  Exposure
While some exposure to sunlight can be enjoyable and healthful, too much can be dangerous. Ultraviolet
radiation (UV) comes naturally from the sun. UV is divided into three different categories based on
wavelength. Wavelength is the distance between two successive peaks of a wave. UV wavelengths are
measured in nanometers (nm) or one billionth of a meter. The shorter the wavelength is, the higher the energy.
    •   UVA wavelengths (315nm) are only slightly affected by ozone levels. Most UVA radiation is able to
        reach Earth's surface and can contribute to sunburn, skin aging, eye damage, and can suppress your
        immune system.
    •   UVB wavelengths (280nm) are strongly affected by ozone levels. Decreases in stratospheric ozone
        mean that more UVB radiation can reach Earth's surface, causing sunburns, snow blindness, immune
        system suppression, and a variety of skin problems including skin cancer and premature aging.
    •   UVC wavelengths (ISOnm) are very strongly affected by ozone levels. Virtually all UVC radiation
        is absorbed by ozone, water vapor,  oxygen and carbon dioxide before reaching Earth's surface.

Therefore, the UV radiation reaching Earth's surface is largely composed of UVA with some UVB.  Almost
half the daytime total UV radiation is received between the hours of 10 a.m. an 4 p.m. Even on a cloudy day,
you can  still get sunburned because of UV radiation.
One in five Americans develops skin cancer, and one person dies from this disease every hour. The incidence
of melanoma, the most serious type of skin cancer, is increasing faster than most other forms of cancer.
Children are of particular concern since most of the average person's lifetime sun exposure occurs before the
age of 18. There are simple protective measures that you can take to limit exposure to UV rays.


Who  is protecting you

U.S. Environmental Protection Agency (EPA)
EPA sponsors the SunWise program, which teaches the public how to protect themselves from overexposure
to the sun. Through the use of classroom-based, school-based, and community-based components, SunWise
seeks to  develop sustained sun-safe behaviors in schoolchildren.

National Oceanic and Atmospheric Administration (NOAA)
EPA worked with the NOAA's National Weather Service to develop the UV Index, which predicts the next
day's ultraviolet radiation levels on a 1-11+  scale, helping people determine appropriate sun-protective
behaviors.

World Health Organization
The World Health Organization revised guidelines for reporting the UV Index. The United States and Canada
both adopted these guidelines and applied them to their current UV Indexes.

U.S. National Institutes of Health  (NIH)
The National Cancer Institute provides prevention, screening, and treatment information for skin cancer.
Together with the EPA, and the Centers for Disease Control and Prevention, the NIH researches methods to
protect against the sun's harmful rays, and provides helpful information to the public.
 United States Environmental Protection Agency
Office of Radiation and Indoor Air (6608J)   |  EPA 402-F-06-045
April 2006
                                                                   www.epa.gov/radtown/sun-exposure.html

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 RadTown  USA
U.S. Food and Drug Administration (FDA)
The FDA establishes rules that govern the makers of sunscreens, particularly product labeling and advertising.
The FDA ensures that the Sun Protection Factor (SPF) for sunscreen is clearly written on its label, and that
consumers clearly understand what SPF means.


What you can do to protect yourself

    •   Time in the Midday Sun. The sun's rays are strongest between 10 a.m. and 4 p.m., so try to avoid
        overexposure to the sun during those hours when possible, even in winter and especially at higher
        altitudes.
    •   Seek Shade: Shade is a good source of protection, but keep in mind that shade structures (e.g., trees,
        umbrellas, canopies) do not offer complete sun protection.
    •   Wear a Hat: Wide brimmed hats offer good sun protection to areas particularly prone to
        overexposure to the sun (i.e., eyes, ears, faces, and necks).
    •   Cover Up: Wear tightly woven, loose-fitting, and full-length clothing.
    •   Wear Sunglasses that Block 99-100% of UV Radiation: Sunglasses that provide 99-100% UVA
        and UVB protection greatly reduce sun exposure that can lead to cataracts and other eye damage.
    •   Always Use Sunscreen: Apply a broad spectrum sunscreen with a Sun Protection Factor (SPF) of 15
        or higher liberally on exposed skin.  Reapply every 2 hours, or after working, swimming, playing, or
        exercising outdoors.
    •   Watch the UV Index:  The UV Index provides important information to help people plan outdoor
        activities in ways that prevent overexposure to the sun.


Resources

You can explore this radiation source further through the resources at the following URL:
http://www.epa.gov/radtown/sun-exposure.htmltfresources

We provide these resources on-line rather than here so we can keep the links up-to-date.
 United States Environmental Protection Agency
Office of Radiation and Indoor Air (6608J)   |  EPA 402-F-06-045
April 2006
                                                                    www.epa.gov/radtown/sun-exposure.html

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