United States
Environmental Protection
Agency
Air and Radiation
6205J
EPA 430-K-06-002
September 2006
www.epa.gov/sunwise
4>EPA The Sun, UV, and You
A Guide to SunWise Behavior
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>Recycled/Recyclable—Printed with vegetable oil based inks on 100% (minimum 50% postconsumer) recycled paper.
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7
', ! hile some exposure to sunlight is enjoyable, too much can be
dangerous. Broad-spectrum ultraviolet (UV) radiation, listed as a
known carcinogen by the National Institute of Environmental
Health Sciences, can cause immediate effects like blistering sun-
burns and long-term problems like skin cancer, cataracts, and
immune suppression. Overexposure also causes wrinkling and
aging of the skin.
The U.S. Environmental Protection Agency (EPA) prepared this
booklet to help you understand the risks from overexposure to the
sun's harmful UV rays and how to protect yourself and your loved
ones from UV radiation.
This booklet presents the following information:
[7 *^-
L J^~ The science behind UV radiation and stratospheric ozone.
[£Tp—I' 1
IfM" ^"he health risks from overexposure to UV radiation.
y^,
The steps you can take to protect yourself and your children.
I^H" What the UV Index is and how you can use it.
yr.
- Details about EPA's SunWise Program.
Ljjr Where to get more information about the UV Index and
ways to protect yourself from the sun.
We hope you find this booklet useful and that you will use the
information provided to help you be SunWise!
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j he sun releases energy over a broad spectrum of wavelengths. UV radiation,
which has a shorter wavelength than visible light, is responsible for sunburn and
other adverse health effects. Fortunately for life on Earth, a gas in the atmosphere
called ozone screens most harmful UV radiation. What gets through the ozone
layer, however, can cause the following health problems, particularly for people who
spend substantial time outdoors:
* Skin cancer and other skin disorders
* Cataracts and other eye damage
* Immune suppression
Because of these adverse health effects, you should limit your exposure to UV radi-
ation and protect yourself when working, playing, or exercising outdoors.
Scientists have classified UV radiation into three
types: 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: Partially absorbed by the ozone layer
UVC: Completely absorbed by oxygen and ozone
in the atmosphere
UVA and especially UVB penetrate into the skin
and eyes, and can cause the adverse health effects
listed above.
UVC
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fcJV levels Depend ttin:a NUHnber of RaieforS''
The ozone layer absorbs most of the sun's harmful UV rays, but its thickness varies
depending on the time of year and changing weather patterns. The ozone layer has
thinned in certain areas due to the emission of ozone-depleting chemicals.
of Day
The sun is at its highest in the sky around noon. At that time, the sun's rays have
the shortest distance to travel through the atmosphere, and UV levels are at their
highest. In the early morning and late afternoon, the sun's rays travel a greater dis-
tance through the atmosphere, and the intensity of UV is greatly reduced.
of Year
The sun's angle varies with the seasons, causing the intensity of UVB rays to vary.
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 where UV rays must travel the shortest distance through the atmosphere.
Ozone also is naturally thinner in the tropics as compared to the mid- and high-lat-
itudes, 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.
Cloud cover reduces UV levels, but not completely. Depending on the thickness of
the cloud cover, it is possible to burn on a cloudy day, even if it does not feel warm
or seem bright.
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I he ozone layer forms a thin shield in the stratosphere, protecting life on Earth
from the sun's harmful UV rays. In the 1980s, scientists began accumulating evi-
dence that the ozone layer was being depleted. Depletion of the ozone layer can
result in increased UV radiation reaching the Earth's surface, which can lead to a
greater chance of overexposure to UV radiation and consequent health effects
including skin cancer, cataracts, and immune suppression.
Ozone is a naturally occurring gas that is found in two layers in the atmosphere. In the
layer surrounding the Earth's surface—the troposphere—ground-level or "bad" ozone is
an air pollutant that damages human health and vegetation and is a key ingredient of
urban smog. The troposphere extends up to the stratosphere, which is where the "good"
ozone protects life on Earth by absorbing some of the sun's UV rays. Stratospheric
ozone is most concentrated between 6 and 30 miles above the Earth's surface.
Ozone is formed when oxygen molecules absorb UV radiation and split apart into two
oxygen atoms (O), which combine with other oxygen molecules (02) to form ozone
molecules (03). Ozone also is broken apart as it absorbs UV radiation. In this way,
UV radiation helps sustain the natural balance of ozone in the stratosphere, while
ozone in turn absorbs UV radiation, protecting life on Earth from harmful radiation.
Until the late 1990's, chlorofluorocarbons (CFCs) and other chemicals were used
widely in industry and elsewhere as refrigerants, insulating
foams, and solvents. They migrate into the upper atmos-
phere after use, carried by air
currents into the stratos-
phere. This process can take as
long as five to 10 years. These chemicals
absorb UV radiation, break apart, and react
with ozone, taking one oxygen atom away and
4
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forming highly reactive chlorine
monoxide. Chlorine monoxide in
turn breaks down 03 again by
pulling away a single oxygen atom,
creating two C>2 molecules, and
allowing the chlorine to move freely
to another ozone molecule. In this
way, each chlorine atom acts as a
catalyst, repeatedly combining with
and breaking apart as many as
100,000 ozone molecules during its
stratospheric life.
Other compounds also damage the
ozone layer in much the same way
as CFCs do. These ozone-depleting
substances include the pesticide
methyl bromide, halons used in fire
extinguishers, and methyl chloro-
form used in industrial processes.
What \$> Being EJ«jHe
Countries around the world have
recognized the threats posed by
ozone depletion and have respond-
ed by adopting the Montreal
Protocol on Substances That
Deplete the Ozone Layer. Parties to
this treaty, including the United States, are phasing out the production and use of
ozone-depleting substances.
i iifj^M j^^ \ iMels}
Chlorine levels in the stratosphere as a result of the emission of CFCs and other
ozone-depleting substances were at or near peak as of early 2000, and are predicted
to fall to pre-1980 levels in the second half of this century. As international control
measures reduce the release of CFCs and other ozone-depleting substances, natural
atmospheric processes will repair the ozone layer. Until that time, we can expect
increased levels of UV radiation at the Earth's surface. These increased UV radia-
tion levels can lead to a greater chance of overexposure to UV radiation and the
consequent health effects.
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to
the
I mericans love the sun and spend a great deal of time outside—working, play-
ing, exercising—often in clothing that exposes a lot of skin to the sun. Most people
are now aware that too much sun has been linked to skin cancer. However, few
know the degree of risk posed by overexposure, and fewer are aware that the risks
go beyond skin cancer. Recent medical research has shown that overexposure to the
sun's UV radiation can contribute to serious health problems. Each year, for exam-
ple, more than 1 million cases of skin cancer are diagnosed in the United States,
and one person dies every hour from skin cancer.
This section provides a quick overview of the major problems linked to excess UV
exposure: skin cancer (i.e., melanoma, basal cell carcinoma, and squamous cell car-
cinoma), other skin problems, cataracts and other eye damage, and immune system
suppression. Understanding these risks and taking a few sensible precautions
described in this booklet will help you enjoy the sun while lowering your chances
of sun-related health problems later in life.
A Risk
Overexposure to UV radiation poses the risk of serious health effects for everyone,
but not everyone is equally at risk. For example, you may be at greater risk of con-
tracting skin cancer if your skin always burns, or burns easily, and if you have
blond or red hair, or blue, green, or gray eyes. Other factors indicating an
increased risk of skin cancer include: a history of blistering sunburns in early
childhood, usually from acute sun overexposure; the presence of many moles; or a
family history of skin cancer. Also, people who work or otherwise spend a large
amount of time outdoors may be at higher risk of adverse health effects. Anyone
can contract skin cancer, and all people, no matter what their skin type, are equal-
ly at risk of eye damage.
Mehfidima
Melanoma, the most serious form of skin cancer, is one of the fastest growing types
of cancer in the United States. Many scientists believe there might be a link
between childhood sunburns and melanoma later in life. According to the
American Cancer Society (ACS), melanoma cases in this country are increasing at a
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rate just below 3 percent a year; ACS also estimates that about 60,000 new cases of
melanoma and just under 8,000 deaths occur annually.
Cure
Melanoma can spread to other parts of the body quickly, but when detected in its
earliest stages it is almost always curable. If not caught early, melanoma is often fatal.
Melanoma begins as an uncontrolled growth of pigment-producing cells in the
skin. This growth leads to the formation of dark-pigmented malignant moles or
tumors, called melanomas. Melanomas can appear suddenly without warning but
also can develop from or near a mole. For this reason, it is important to know the
location and appearance of moles on the body so any change will be noticed.
Melanomas are found most frequently on the upper backs of men and women, and
the legs of women, but can occur anywhere on the body. Be aware of any unusual
skin condition, especially a change in the size or color of a mole or other darkly or
irregularly pigmented growth or spot; scaliness, oozing, bleeding, or change in the
appearance of a bump or nodule; spread of pigment from the border into sur-
rounding skin; or change in sensation including itchiness, tenderness, or pain.
Nortmilandma SMit Cancer s?
Unlike melanoma, nonmelanoma skin cancers are rarely fatal. Nevertheless, they
should not be taken lightly. Untreated, they can spread and cause more serious
health problems. According to ACS, more than 1 million Americans will develop
nonmelanoma skin cancers this year, and more than 2,800 will die from the dis-
ease.
There are two primary types of nonmelanoma skin cancers:
Basal Cell Carcinomas are tumors of the skin that usually appear as small, fleshy
bumps or nodules on the head and neck but can occur on other skin areas as well.
It is the most common skin cancer found among fair-skinned people. Basal cell car-
cinoma does not grow quickly and rarely spreads to other parts of the body. It can,
however, penetrate below the skin to the bone and cause considerable local damage.
Squamous Cell Carcinomas are tumors that might appear as nodules or as red,
scaly patches. The second most common skin cancer found in fair-skinned people,
squamous cell carcinoma is rarely found in darker-skinned people. This cancer can
develop into large masses, and unlike basal cell carcinoma, it can spread to other
parts of the body.
Cure
These two nonmelanoma skin cancers have cure rates as high as 95 percent if
detected and treated early. The key is to watch for signs and to detect the cancer in
its early stages.
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Basal cell carcinoma tumors usually appear as slowly growing, raised, translucent,
pearly nodules that, if untreated, might crust, discharge pus, and sometimes bleed.
Squamous cell carcinomas usually are raised, red or pink scaly nodules, or wart-like
growths that form pus in the center. They typically develop on the edge of the ears,
the face, lips, mouth, hands, and other exposed areas of the body.
These sun-induced skin growths occur on body areas exposed to the sun. The face,
hands, forearms, and the "V" of the neck are especially susceptible to this type of
blemish. They are premalignant, but if left untreated, actinic keratoses can become
malignant. Look for raised, reddish, rough-textured growths. See a dermatologist
promptly if you notice these growths.
Chronic exposure to the sun causes changes in the skin called actinic (or solar) degen-
eration. Over time, the skin becomes thick, wrinkled, and leathery. Since it occurs
gradually, often manifesting itself many years after most of a person's exposure to the
sun, this condition is often regarded as unavoidable, a normal part of growing older.
With proper protection from UV radiation, however, premature aging of the skin can
be substantially avoided.
Cataracts are a form of eye damage where a loss of transparency in the lens clouds
vision. Left untreated, cataracts can rob people of vision. Research has shown that
UV radiation increases the likelihood of certain cataracts. Although curable with
modern eye surgery, cataracts diminish the eyesight of millions of Americans and
necessitate billions of dollars of eye surgery each year. Other kinds of eye damage
include: pterygium (tissue growth on the white of the eye that can block vision), skin
cancer around the eyes, and degeneration of the macula (the part of the retina near
the center, where visual perception is most acute). All of these problems could be
lessened with proper eye protection from UV radiation.
Scientists have found that sunburn can alter the distribution and function of disease-
fighting white blood cells in humans for up to 24 hours after exposure to the sun.
Repeated exposure to UV radiation might cause more long-lasting damage to the
body's immune system. Mild sunburns can suppress immune functions in people of
all skin types.
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Protecting yourself from overexposure to UV radiation is simple if you follow the
action steps below daily.
O;
Do Not Burn. Five or more sunburns double your risk of
developing skin cancer.
UV light from
tanning beds and the sun causes skin cancer and wrinkling. If you
want to look like you've been in the sun, consider using a sunless
self-tanning product, but continue to use sunscreen with it.
to all exposed skin using a Sun
Protection Factor (SPF) of at least 15 that provides broad-
spectrum protection from both ultraviolet A (UVA) and ultraviolet
B (UVB) rays. Reapply every two hours, even on cloudy days, and
after swimming or sweating.
such as a long-sleeved shirt, pants,
a wide-brimmed hat, and sunglasses, where possible.
Seek Shade when appropriate, remembering that the sun's UV
rays are strongest between 10 a.m. and 4 p.m.
Use as they
reflect the damaging rays of the sun, which can increase your
chance ofsunburn.
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for the U¥ The 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 and EPA, the UV Index is issued daily nationwide.
D through a diet that includes vitamin
supplements and foods fortified with Vitamin D. Don't seek the sun.
Early detection of melanoma can save your life. Carefully examine ALL of
your skin once a month. A new or changing mole in an adult should be
evaluated by a dermatologist.
The UV Index describes the next day's likely levels of the intensity of UV rays.
The Index predicts UV levels on a 1 to 11+ scale in the following way:
UV Index Number
2 or less
3 to 5
6 to 7
8tolO
ll +
Exposure Level
Low
Moderate
High
Very High
Extreme
The higher the UV Index forecast, the stronger the sun will be, and the greater
the need to follow all the sun protection action steps.
Some medications cause serious sun sensitivity, as do some diseases such as
lupus erythematosus. The UV Index is not intended for use by seriously sun-
sensitive individuals. Consult your doctor about additional precautions you
might need to take.
See the UV Index Scale with suggested action steps for each exposure category
online at .
V3
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UV INDEX
I he National Weather Service uses a
computer model to calculate the next
day's UV levels for selected cities across the
United States. The model takes into
account a number of factors including the
amount of ozone and clouds overhead, lat-
itude, elevation, and time of year.
To compute the UV Index forecast, the
model first calculates a UV dose rate, or
amount of UV radiation to which a per-
son will be exposed at the next day's solar
noon (when the sun is highest in the sky)
under "clear sky" (no clouds) conditions.
The UV dose rates obtained from the
model are then adjusted for the effects of
elevation and cloud cover at specific loca-
tions. Higher elevations will increase the
UV dose rate because there is less atmos-
phere to absorb and scatter UV rays.
Greater cloud cover will tend to reduce the
UV dose rate because clouds screen out
some—but not all—UV rays.
What Is the UV Alert?
EPA issues a UV Alert when
the level of solar UV radiation
reaching your local area is
predicted to be unusually
intense for the time of the year.
It is a warning that the risk of
overexposure to UV radiation
is high on that day, and it
offers simple steps you can
take to protect yourself and
your family.
EnviroFiasli
To receive the UV Alert or the
daily UV Index via email,
please sign up at
.
The resulting value is the next day's UV Index forecast. The UV forecasts are pro-
vided daily on a 1 to 11+ scale, where 1 indicates a low level of exposure to UV
rays and 11+ means an extreme level of exposure.
For more information about the UV Index, or to sign up for daily e-mails contain-
ing the next day's UV Index and Alert forecasts, please consult
.
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for
Ithough many of the sun's harmful effects do not appear until later in life, it is
never too early to educate children and young adults about overexposure to UV
radiation. Protection from UV in childhood is especially important because about a
quarter of a person's lifetime exposure occurs before the age of 18.
Take special care with children, since they usually do not understand the dangers of
UV radiation and often sunburn more easily. The precautions described in this
booklet can help ensure that the children around you avoid UV-related health prob-
lems, both now and later in life. Started early and followed consistently, each of
these steps will become an accepted habit, as easy as fastening seatbelts every time
you drive the car.
In response to the serious public health threat posed by overexposure to UV radia-
tion, EPA is working with schools and communities across the nation to expand
the SunWise Program. SunWise teaches children in grades K-8 and their caregivers
how to protect themselves from overexposure to UV radiation. Educating children
about sun safety is the key to reducing the risk of future UV-related health problems.
Participating schools will sponsor activities that raise children's awareness of the
largely preventable health risks from UV radiation and teach simple steps to avoid
overexposure. Such activities might include:
* Cross-curricular classroom lessons.
» Reporting the UV Index and UV ground data on the SunWise Internet
Learning Site.
* Infrastructure enhancements (e.g., policy changes and shade structures).
* Community partnerships.
» Schoolwide sun safety activities.
* Train-the-trainer activities and materials.
For additional information about the SunWise Program, please contact EPA's
Stratospheric Ozone Information Hotline at (800) 296-1996 or visit the program's
Web site at .
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a program that radiates good ideas
A Partnership Program of the U.S. Environmental Protection Agency
www.epa.gov/sunwise
For More Information
mM o learn more about the UV Index, UV Alert, and how to protect
yourself from overexposure to the sun's UV rays, call EPA's Stratospheric
Ozone Information Hotline at (800) 296-1996 or visit the SunWise Web
site at . Hotline staff can supply you with the fol-
lowing fact sheets and other useful information, some of which is also
available online at :
• Health Effects of Overexposure to the Sun
• UV Radiation
• Action Steps for Sun Protection
• Sunscreen: The Burning Facts
• Summertime Safety
• Prevent Eye Damage - Protect Yourself from UV Radiation
• Ozone Depletion
• Ozone: Good Up High, Bad Nearby
• What is the UV Index?
• The SunWise Program Guide
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