United States
Environmental Protection
           A  GUIDE   TO  THE

                                  The  UV  Index  is  Changing.
The  Ultraviolet (UV) Index, developed  in  1994
by the National Weather Service (NWS) and the
U.S.  Environmental Protection Agency  (EPA),
helps Americans plan outdoor activities to avoid
overexposure to UV radiation and  thereby lower
their  risk  of  adverse
health effects. UV radia-
tion  exposure  is a  risk
factor  for  skin  cancer,
cataracts,  and other  ill-
nesses. The incidence of
skin  cancer,  including
melanoma,  has increased
significantly in  the United
States  since  the  early
                                   MELANOMA INCIDENCE IN THE UNITED STATES
                                   (per 100,000 people)
                                   Source: National Cancer Institute
                                   SEER Program            16.3

                        The UV Index is a  useful tool to help the general public take steps to
                        reduce their exposure to solar UV radiation, but its effectiveness depends
                                       on how well the  information is communicated to the
                                       public. This brochure provides important information on
                                       new reporting guidelines for solar ultraviolet radiation.
                                       It is intended to  assist communicators in  several
                        fields — meteorology, public health, education, and the news media —
                        in conveying UV information to the public. Professionals in these fields
                        are uniquely positioned to raise awareness of how to prevent skin cancer.

                        Beginning in May 2004, EPA and NWS will report the UV Index consistent
                        with guidelines recommended  jointly in  2002  by  the World  Health
                        Organization (WHO), the World Meteorological Organization, the  United
                        Nations Environment Programme, and the International Commission on
                        Non-Ionizing Radiation Protection. These organizations recommended a
                        Global  Solar UV Index in order to bring worldwide consistency to UV reporting
                        and  public health messaging.

            The UV Index informs the public of the level
            of UV exposure expected  on a given day. It is
            reported as a prediction  of the UV  level  at
            noon, although the actual UV level rises and
            falls  as the day progresses.

What's New About the
                              UV  Index?
                            UV Index Variation During a Summer Day
                                St. Louis, Missouri, June 20,2Bu3
                                                                    SAM  11AM 1PM  4PM
                                                                        TIME OF DAY
        UV Index
     Prior to May 2004
     The New
Global Solar UV Index








                       The UV I ndex was previously reported on
                       a scale of 0 to 10+, with 0 representing
                       "Minimal" and 10+ representing
                       "Very High." As of May 2004, EPA and
                       NWS will  report the Global Solar UV
                       Index using a scale of 1 (or "Low")
                       to 11 and higher  (or "Extreme").
                       Additional differences include a new
                       color scheme, revised exposure
                       categories, and different breakpoints
                       between exposure categories.
                       Although  the categories have been
                       reorganized and labeled, actual
                       UV levels  associated with the exposure
                       categories in the Global Solar UV
                       Index have not changed. In other words,
                       a UV index report of 6 represents the
                       same intensity  UV radiation on both
                       the old and new scales, even if 6 is
                       called "Moderate" on the old scale
                       and "High" on  the new scale.
Consistent reporting of the index will help  the public better understand
UV risk. We therefore strongly urge providers  of  the UV Index to
adopt the new scale and color scheme.  The color scheme ranges
from green (for "Low") to violet (for "Extreme").

The UV Index reminds people to protect themselves when engaging in their
normal  outdoor activities. UV  radiation  exposure poses varying degrees of
risk for all people because it affects eyes and skin. People with sensitive skin
should always take action to protect themselves. It is especially important
that parents and caregivers know how to protect  babies and young children
who are more susceptible to overexposure.
EPA recommends that communicators
always encourage individuals to
understand and practice the following
sun protection steps:

• Check the UV Index for the UV forecast.

• Limit exposure during midday hours.

• Seek shade.

• Wear clothing made from tightly
 woven fabrics. UV rays can pass
 through holes and spaces in loosely
 knit fabric.  Long-sleeved shirts and
 pants are recommended.

• Wear a hat with a wide brim that
 protects the eyes, face, and neck.

• Wear sunglasses that provide 100%
 UV protection.

• Use broad spectrum sunscreens with
 at least Sun  Protection Factor (SPF)
 15 and reapply regularly. Remember
 to apply sunscreen on any part of the
 skin that is exposed to the sun, such
 as the nose, the back of the neck, and
 the rims of the ears.  Use lip balms or
 creams containing sunscreen.
                                         the  UV  Index
When used correctly, shade, clothing, and hats provide the best protection from
UV radiation. While sunscreen is effective when applied properly, doctors caution
that sunscreen should not be used to prolong the duration of sun exposure.

Sun Protection Messages

When reporting or discussing the UV Index, it might be helpful to give your audience
more information about the significance of the reported UV Index for a given day
by suggesting simple actions they can take to avoid overexposure. For this reason,
EPA recommends that you use some of the messages identified in the chart below
when reporting the UV Index. The Myths and Realities About Fun in the Sun on
page 6 of this brochure may also be useful as "health tips."
J H,CH )
Sun Protection Messages
• Wear sunglasses on bright days. In winter, reflection off snow can nearly double UV strength.
• If you burn easily, cover up and use sunscreen.
• Take precautions, such as covering up and using sunscreen, if you will be outside.
• Stay in shade near midday when the sun is strongest.
• Protection against sunburn is needed.
• Reduce time in the sun between 11 a.m. and 4p.m.
• Cover up, wear a hat and sunglasses, and use sunscreen.
• Take extra precautions. Unprotected skin will be damaged and can burn quickly.
• Try to avoid the sun between 11 a.m. and 4 p.m. Otherwise, seek shade, cover up, wear a hat and
sunglasses, and use sunscreen.
• Take all precautions. Unprotected skin can burn in minutes. Beachgoers should know that white sand
and other bright surfaces reflect UV and will increase UV exposure.
• Avoid the sun between 11 a.m. and 4 p.m.
• Seek shade, cover up, wear a hat and sunglasses, and use sunscreen.

  Variations in the UV Index
  The intensity of the sun's
  UV rays reaching the earth's
  surface, and the UV Index
  ratings, vary according to
  many factors. All  influence
  the UV Index in locations
  across the U.S.
CLOUD COVER, if heavy, can block
most UV radiation. Thin or broken
clouds allow most UV rays through.
Puffy, fair-weather clouds deflect
rays and can increase UV radiation
reaching the surface.
             OZONE absorbs UV radiation.
             The higher the amount of ozone,
             the fewer rays reach the surface.
             Ozone levels vary from day to day
             and throughout the year.
                                 ALTITUDE affects UV radiation;
                                 UV increases about 2% for every
                                 1,000-foot increase in elevation
                                 due to thinner mountain air.
         TIME OF DAY affects UV radiation,
       which peaks at midday (with the sun
       highest in the sky), and lessens in the
          early morning and late afternoon.
             LAND COVER, such as
               structures and trees,
         significantly reduces exposure
                    to UV radiation
                                             SEASONS affect UV
                                             radiation, which peaks
                                             in spring and summer
                                             (April to August),
                                             declines in fall, and is
                                             lowest in winter.
                                                                                          EARTH SURFACE CHARACTERISTICS
                                                                                          can reflect or scatter UV radiation.
                                                                                          Snow may reflect as much as 80% of
                                                                                          UV, sand 15%, and water 10%.
                                            LATITUDE affects UV radiation,
                                            which is strongest at the equator and
                                            declines toward the poles.
The UV Index represents the amount of skin-damaging UV
radiation reaching the earth's surface at any instant of time.
The basic UV Index forecast is given for solar  noon — the
sun's highest point in the sky and the time of the highest
fluctuation in UV radiation  (under clear sky conditions).
A UV Index forecast begins with a forecast of the  total ozone
amount. All  the forecast parameters used in the UV Index
computation are derived from NWS forecast models. The  sun
angle at solar noon (or for any other time) for that day is
determined.  A radiative transfer model determines the flux of
UV radiation  for a range of wavelengths. An action spectrum
weights the response of the human skin to UV radiation at
each wavelength. Once weighted,  the flux values are integrated
over  the entire range, resulting in an erythemal dose rate —
the instantaneous amount of skin-damaging radiation reaching
the surface under clear sky, at sea level, with  low aerosol
conditions, as measured by units of milliwatts per square
meter.  Adjustments then account for a location's  elevation,
aerosol, and cloud conditions. Next, the optical properties
of cloud conditions expected at that time refine the dose
rate further.  Finally, the resultant dose rate is  applied to  the
UV Index. One UV Index unit is equivalent to  25  milliwatts
per square meter.
Different areas of the country have different degrees of variation
in the UV Index from day to day and from season to season.
Communicators should consider how best to report the UV Index
value to their audience so that people actually put recommendations
into practice and use the UV Index as a guide to healthy behavior.
If  UV levels in your area  tend to be unchanging— particularly if
they are consistently high during summer months — EPA suggests
that you emphasize general sun protection steps (for example,
reminding people to wear sunglasses with 100% UVA &  UVB
protection);  make note of local factors that can affect daily UV
levels; and encourage special  protection for children.
                               AVERAGE UV INDEX VALUE

                          Winter              Summer
Atlanta, Georgia
Phoenix, Arizona
Anchorage, Alaska
Honolulu, Hawaii
New York, New York
Portland, Oregon
St. Louis, Missouri
Miami, Florida
2 (Low)
3 (Moderate)
<1 (Low)
6 (High)
1 to 2 (Low)
1 (Low)
1 to 2 (Low)
4 (Moderate)
8 (Very High)
10 (Very High)
3 to 4 (Moderate)
11 to 12 (Extreme)
6 to 7 (High)
5 to 6 (Moderate-High)
7 to 8 (High-Very High)
10-11 (Very High-Extreme)
   Typical UVI values for different parts of the U.S. at midday. These values
   may vary significantly depending on cloud cover and ozone levels.

Overexposure to the suns ultraviolet  rays is the most
important  preventable factor  in  the  development  of
skin cancer. Skin  cancer is largely preventable  when
sun protection measures  against
UV rays are  used consistently.              \\slC
However,  many young  people
and  adults do  not consistently    s^r^sJ    ^i  i
use  sun  protection  measures    Cll  IU      U
and  are  unaware  of  the  link
between    overexposure   and
health risks.
                                            UV   Radiation
                                            and  Public  Health
         Reporting Burn Times Not Recomm

         Communicators sometimes report

         "time to burn" in lieu of the UV

         Index level, as a simple concept that

         can easily be translated into action.

         However,  people can interpret burn

         times as a safe period during which

         they do not have to take protective

         action. Relating UV Index values to

         "time to burn" or "safe tanning time"

         sends an  incorrect and potentially

         harmful message to the general

         public. The UV Index should not be

         used to suggest that unprotected

         exposure  is risk-free.
                                                                    es About Fun in the Sun
                                          A suntan is healthy.
                                          Establishing a base suntan
                                          protects you from sun damage.
                                           You cannot get a sunburn on
                                           a cloudy day.
                                           UV radiation during winter
                                           is not a concern.
A tan results from the body defending itself
against further damage from UV radiation.
Any change in your skin's natural color is
a sign of damage to the skin.
Sunburn is possible on a cloudy day. Up
to 80% of solar UV radiation can penetrate
light cloud cover.
UV radiation is generally lower in winter,
but snow reflection can double overall
exposure — especially at high altitudes —
leading to sunburn and snowblindness.
                                          Sunscreen protects you so that
                                          you can sunbathe much longer.
Sunscreen should not be used to increase
sun exposure time but to increase
protection during unavoidable exposure.
                                                    If you take breaks while
                                                    sunbathing, you won't get
                                                                       UV radiation exposure is cumulative during
                                                                       the day.
                                                    If you don't feel the sun's hot
                                                    rays, you won't get sunburn.
                                                    Skin cancer only occurs on
                                                    parts of the body that are
                                                    exposed to the sun all the time.
                                                                       Sunburn is caused by UV rays that cannot
                                                                       be felt. The heating effect is caused by the
                                                                       sun's infrared radiation and not by UV.

                                                                       Melanoma occurs most commonly on the
                                                                       back (for men) and legs (for women), which
                                                                       are sites with only intermittent exposure.
                                                    Skin cancer only happens to
                                                    people who are very fair-skinned.
Skin cancer commonly occurs in people
who tan before they burn.

                                'ISK FACTORS
   Everybody, regardless of race or ethnicity,  is subject to the adverse effects
   of overexposure to the sun. Some people might be more vulnerable to certain
   conditions, however.
   Skin type affects the  degree to which some people burn and the time it
   takes them to burn. The Food and Drug Administration (FDA) classifies skin
   type on a scale from  1 to 6. Individuals with lower-number skin types (1
   and 2) have fair skin  and tend to burn rapidly and more severely. Individuals
   with higher-number skin types (5 and 6), although capable of burning, have
   darker skin and do not burn as easily.
   The same individuals who are most likely to burn are also most vulnerable to
   skin cancer. Studies have shown that individuals with large numbers of freckles
   and moles have a higher risk of developing skin cancer. Although individuals
   with darker skin types are less likely to develop skin cancer, they should still
   take action to protect their skin and eyes from overexposure to the sun.
UV radiation causes genetic mutations
in skin cells. Over time, such mutations
due to exposure to the sun and severe
sunburns can lead to skin cancer. Every
year, more than one million Americans
are diagnosed with skin cancer, making
it the most common form of cancer in
the country. In the United States, one
person dies of skin cancer every hour.
The most common places for skin
cancer to develop are on those body
parts exposed to  the sun, such as the
face, neck, ears,  forearms, and hands.
The three main types of skin  cancer
are basal cell carcinoma, squamous
cell carcinoma, and melanoma.
• Basal carcinomas are tumors that
  usually appear as small, fleshy bumps
  or nodules.
• Squamous cell  carcinomas appear as
  nodules or as red, scaly patches.

• Melanomas may appear without
  warning as a dark mole or other dark
  spot in the skin. Melanoma causes
  more than 75% of skin cancer deaths.
  There are more than 50,000 new
  cases of melanoma per year. One  in
  four persons who develop melanoma
  is under 40.
All three types of skin cancer may be
successfully treated if detected in their
early stages. Fa more information about how
to detect skin cancer, visit the Center for
Disease Control's skin cancer website at
The most obvious result of too much
UV exposure is sunburn, which
involves skin redness and sometimes
tenderness, swelling,  blistering, fever,
and nausea. However, tanned skin
also poses a skin cancer risk.

Some people may develop bumps,
hives, blisters,  or red blotchy areas as
an allergic reaction to sun exposure.
Certain drugs, perfumes, and cosmetics
also may make some  people sensitive
to the sun.

Excess exposure to UV radiation  can
cause a painful burn of the cornea.
Chronic eye exposure to UV radiation
may also increase the incidence  of
cataract, which is a clouding of the
eye lens; pterygium,  in which a flesh
membrane  covers the eye; and
possibly macular degeneration, or the
development of spots that could result
in blindness. About 13 million Americans
age 40 or older have  cataracts, and
more than half of all Americans 65 or
older have some evidence of cataracts.
In the long run, too much exposure to
the sun  may change the skin's texture,
giving it a tough, leathery appearance.
Up to 90 percent of the visible skin
changes commonly attributed to aging
are caused by sun exposure. The sun
also may cause discolorations in skin
tone including red, yellow, gray, or
brown spots.

Sun exposure suppresses  the immune
system and may make the body more
vulnerable to  infections and cancers,
regardless of an individual's skin type
or susceptibility to burns.



Additional sun safety information from EPA's SunWise Program is available by calling the National Service Center
for Environmental Publications at 1-800-490-9198.

The Environmental Protection Agency offers a free SunWise Kit to meteorologists. The kit provides fun and interactive
ways to teach kids about UV science and sun safety. Information is available at http://www.epa.gov/sunwise.

EPA also offers next-day UV Index forecasts by ZIP code for the continental United States, contoured UVI maps,
and additional UVI information at http://www.epa.gov/sunwise/uvindex.html.

The National  Weather Service provides UVI forecasts for 58 cities, UVI climatologies, and additional information
at http://www.cpc.ncep.noaa.gov/products/stratosphere/uv_index/index.html.

The World Health Organization's INTERSUN  program has developed a graphics  package, including a UVI logo, an
international color code for different UVI values, and a choice of ready-made graphics for reporting the UVI and
sun safety messages. The materials may be downloaded and used free of charge. An overview of these graphics
is available at http://www.who.int/entity/uv/publications/en/UVIclip.pdf. GIF images may be downloaded at
http://www.who.int/docstore/peh-uv/UVIndex_Graphics/gif. To request  a CD-ROM containing formats other than
GIF, please contact UVinfo@who.int.
                                  United States
                                  Environmental Protection
Air and Radiation
May 2004