v>EPA
United States
Environmental Protection
Agency
United States
Environmental Protection
Agency
Air and Radiation
6205J
EPA 430-F-10-027
June 2010
www.epa.gov/ozone/strathome.html
Ozone Layer Depletion
The stratospheric ozone layer forms a thin shield in the upper atmosphere, protecting life on Earth from
the sun's ultraviolet (UV) rays. It has been called the Earth's sunscreen. In the 1980s, scientists found
evidence that the ozone layer was being depleted. Depletion of the ozone layer results in increased UV
radiation reaching the Earth's surface, which in turn leads to a greater chance of overexposure to UV
radiation and the related health effects of skin cancer, cataracts, and immune suppression. This fact sheet
explains the importance of protecting the stratospheric ozone layer.
What is Stratospheric Ozone?
Ozone is a naturally-occurring gas that can be good or bad for your health and the environment
depending on its location in the atmosphere. In the layer near the Earth's surface—the troposphere—
ground-level or "bad" ozone is an air pollutant that is a key ingredient of urban smog. But higher up, in
the stratosphere, "good"
ozone protects life on Earth
by absorbing some of the
sun's UV rays. An easy way
to remember this is the
phrase "good up high, bad
nearby."
Ozone Layer Depletion
Compounds that contain
chlorine and bromine
molecules, such as methyl
chloroform, halons, and
chlorofluorocarbons
(CFCs), are stable and
have atmospheric lifetimes long enough to be transported by winds into the stratosphere. When these
ozone-depleting substances (ODS) break down in the atmosphere, they release chlorine or bromine,
which attack ozone. Each chlorine or bromine atom reacts with ozone, repeatedly combining with and
breaking apart as many as 100,000 ozone molecules during its stratospheric life.
CFCs, which have a long history of use as refrigerants, solvents, foam-blowing agents and in other
applications, have been almost completely phased out worldwide. In addition, restrictions are now in
place to phase out hydrochlorofluorocarbons (HCFCs), compounds used as substitutes for the more
damaging CFCs. The U.S. will phase out HCFCs completely in 2030.
What is Being Done?
In 1987, the U.S. and fewer than 30 other countries signed the Montreal Protocol treaty to phase out the
production and use of ODS. In September 2009, the Montreal Protocol became the first international
agreement to reach universal participation, with 196 Parties. The Protocol continues to phase out ODS
worldwide. As international control measures reduce the release of ODS, natural atmospheric processes
will repair the ozone layer during the second half of the 21st century.
Ozone "up high " in the stratosphere protects the Earth, while ozone close to the Earth's
surface is harmful.
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Total Ozone (Dobson Units)
110 220 330 440 550
The Largest Ozone Hole To Date
According to NASA scientists, from September 21
to 30, 2006, the average area of the ozone hole
was the largest ever observed, at 10.6 million
square miles. The hole is a seasonal occurrence
over the South Pole that occurs because of special
weather conditions in the Antarctic.
Source: National Aeronautics and Space
Administration (NASA)
What You Can Do
• Visit www.epa.gov/ozone/strathome.html for
more information on the science of ozone
depletion, EPA's regulatory programs, ODS
alternatives, the phaseout of HCFC
refrigerants, and more.
• Properly dispose of your appliances—this
will reduce emissions of ODS and greenhouse
gases into the atmosphere. See www.epa.gov/
ozone/partnerships/rad for more information.
• Shop for energy-efficient appliances, such as
those with EPA's ENERGY STAR® label.
• Be SunWise. Visitwww.epa.gov/sunwiseto
learn how to safely enjoy the great outdoors
under a compromised ozone layer.
What is EPA Doing About Ozone Layer
Depletion?
• Ending the production, import and use of ODS,
often ahead of the Montreal Protocol schedule;
• Ensuring that ODS are recycled properly, and
prohibiting unnecessary releases of ODS;
• Identifying safe alternatives through the Significant
New Alternatives Policy (SNAP) program;
• Banning the release of ozone-depleting refrigerants
during the service, maintenance, and disposal of air
conditioners and other refrigeration equipment;
and
• Requiring that manufacturers label products
containing or made with the most harmful ODS.
EPA's SunWise Program
In response to the serious public health threat posed by
exposure to increased UV levels, EPA is working with
schools and communities across the nation through the
SunWise Program. SunWise is an environmental and
health education program that teaches children and
their caregivers about ozone depletion, UV radiation,
and how to protect themselves from overexposure to
the sun. For more information, visit www.epa.gov/
sunwise.
The UV Index
The UV Index forecasts the strength of the sun's
harmful rays. The higher the number, the greater the
chance of sun damage.
1 2 3 4 5 6 7 8 9 10
Visitwww.sunwise.gov/uvindex.html
For More Information
To learn more about ozone depletion, the Montreal
Protocol, and the SunWise Program, call EPA's
Stratospheric Ozone Information Hotline at 800.296.1996,
or visit our Web site at www.epa.gov/ozone/
strathome.html.
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