United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park, NC 27711
EPA-451/F-93-011
January 1994
Ozone is the same whether
it is high altitude or ground-level.
However, it protects us high above
the earth but can be bad for us
to breathe near the ground.
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GROUND-LEVEL OZONE
What Is it?
• Though it acts as a protective layer high above the earth, ozone can be harmful to breathe. It is the prime ingredient of smog in our
cities:.
Why is there a problem?
• 0/one is not emitted directly into the air but rather is formed by gases called nitrogen oxides (NOx) and volatile organic compounds
(VOCs) that react with oxygen in the air in the presence of strong sunlight, creating effects of concern when temperatures are higher during
summer.
• Ground-level ozone forms readily in the atmosphere in hot weather. On warm days, VOCs and NQx "bake" together in the sun forming
ozone concentrations which can remain high over large regions. Many urban areas tend to have high ozone levels. However, areas downwind
of urban settings are also subject to high ozone exposure as winds carry VOCs and NOx Irom their original sources.
• Clwnging weather patterns (especially the number of hot, sunny days) and periods of air stagnation create yearly differences in orane
concentrations. It is often difficult to make long-term predictions concerning ground-level ozone because the number pi bad o/.one days
varies greatly from one year to the next and there are so many factors which influence ozone formation.
Health and environmental effects of ground-level ozone
When inhaled, ozone can damage the lungs.
Relatively low amounts of ozone can cause chest pain, coughing,
nausea, throat irritation, and congestion. It may also worsen bronchitis,
heart disease^emphysema, and asthma.
Hjallhy people as well as those with respiratory problems,
experience breathing problems when exposed to ozone.
The EnvironmenUil Protection Agency has established a maximum
OOTne health standard. A single hour of exposure to ozone at this level is
sufficient to cause negative respiratory effects. In fact, 13 million U. S.
adults are currently exposed to ozone levels above the health standard for
at least one hour in the summer. During heavy exercise these people are at
particular risk for short-term health effects. Many more individuals maybe
repeatedly exposed to lower ozone levels which may cause long-term
adverse effects. About 64 million people live in areas with ozone levels
greater lhan the maximum health standard.
SOURCES OF
MANMADE VOC AND NOx
AIR POLLUTION
SOLVENTS,
CONSUMER
PRODUCTS,
AND OTHER SMALL
SOURCES
CHEMICAL
PLANTS,
FACTORIES,
AND OTHER
INDUSTRIAL
SOURCES
MOTOR VEHICLES AND FUELS
Ground-level ozone interferes with the production and storage of starches within
plants, reducing their growth rates.
• It dmnages the quality of crops (such as corn, wheat, and soybeans), making them •
less valuable on the market and can substantially reduce crop yield.
Ozone reduces the ability of trees and plants to fight disease.
• Agricultural crop losses of S2 to $3 billion dollars per year have been estimated attributable to ozone exposure; the extent of forest
damage is currently being studied. Ozone has been shown to damage various tree seedlings.
What is being done about the problem?
• The Clean Air Act of 1990 requires EPA, states, and cities to implement a series of programs that will further reduce emissions of
07-one-causing VOCs and NOx from cars, fuels, industrial and chemical facilities, power plants, and consumer and commercial products among
Other sources. Cleaner cars and fuels, new kinds of gasoline nozzles, enhanced vehicle inspection, and other programs will be phased in over
the next decade.
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HIGH ALTITUDE OZONE
What is it?
In the stratosphere, high altitude ozone forms a protective layer 10 to 35 miles above the earth to shield us from the sun's harmful
ultraviolet (UV) rays. Ozone is naturally produced and destroyed at a constant rate in the stratosphere.
Why is there a problem? •
Stratospheric ozone is gradually being destroyed by chemicals called chlorofluorocarbons (CFCs) and other ozone-depleting substances.
These ozone depleters degrade slowly and can remain intact until they reach the stratosphere. There they are broken apart by the sun's
ultraviolet rays. This reaction sets free the chlorine or bromine molecules of these chemicals, allowing them to attack and destroy the
protective ozone blanket. .
It can take decades for them to reach the upper atmosphere. Ozone-depleting substances released today will contribute to ozone
destruction many years from now. One CFC molecule can lead to the elimination of 100,000 ozone molecules. Consequently, ozone is
disappearing much faster than it is being replaced naturally.
• Satellite information indicates ozone losses on a global scale. The most significant losses have occurred over the North and South poles
because ozone depletion occurs rapidly in extremely cold weather conditions. Fluctuating weather cycles affect the level of ozone in the
stratosphere. This makes it difficult for scientists to accurately predict the future condition of the ozone layer.
SOURCES OF
OZONE DEPLETING SUBSTANCES
36.1%
12.0%/OTHER
/PRODUCTS
/ INCLUDING
/ HALONS
AEROSOLS _ -- ^
/3.n%
"
\
14.3%
FOAM PRODUCTS/ REFRIGERATION
• - • / AND
AIR CONDITIONING
/
--'' 29.6%
Health and environmental effects if high-altitude ozone is decreased:
Increases in the number of skin cancer cases and eye cataracts (which
can cause blindness) from reduced ozone blockage of harmful UV
rays: the United Nations estimates a 26 percent increase in skin cancer
cases, 1.6 million more cataract cases, and 24,000 deaths from melanoma
(a serious form of skin cancer) worldwide by the end of the decade.
Damage to crops sensitive to additional UV radiation, such as
soybeans.
Ozone depletion is suspected to cause decreases in phytoplankton, a
plant within the ocean. Decreased phytoplankton could:
1) reduce the amount of fish (since phytoplankton is an
important plant in the marine food chain).
2) increase the level of carbon dioxide in the atmosphere,
because plants "breathe in" carbon dioxide and "breathe out"
oxygen. • _
Increased UV radiation can be instrumental in forming more
ground-level ozone.
What is being done about the problem?
In 1987 the United States entered into a series of international agreements called the Montreal Protocol which were designed to limit
and eventually eliminate world-wide production of ozone-depleting substances by the turn of the century. Under the Clean Air Act of 1990
the US Environmental Protection Agency (EPA) is accelerating the schedule for phasing out CFCs and certain other ozone-depleting
substances to the end of 1995.
The Clean Air Act requires the use of warning labels on all products containing CFCs or similar substances and prohibits non-essential
ozone-depleting products such as fog horns. Also, releasing refrigerants into the atmosphere which are used in car air conditioners, home
air conditioners, or appliances is prohibited.
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WHAT CAN YOU DO?
i
High Altitude Ozone:
'
i
• Make sure that technicians working on your car air conditioner, home air conditioner, or refrigerator recover the refrigerant
(this is required by law).
* Have your car and home air conditioner units and* refrigerator checked for leaks. When possible, repair leaky air conditioning
units before refilling them.
• Properly dispose of refrigeration or air conditioning equipment (this is required by law).
* Protect yourself against intense sunburn. Wear UV screening sunglasses and hats to shield yourself from harmful
UV rays. Also, apply sunscreen.
Ground-Level Ozone.
* Keep your automobile well tuned and maintained.
• Carpool and/or reduce driving.
• Be careful not to spill gasoline when filling up your car, or gasoline powered lawn and garden equipment.
* Make sure your tires are properly inflated and your wheels aligned.
• Participate in your local utility's energy conservation programs.
* Seal containers containing household cleaners, workshop chemicals and solvents, and garden chemicals to prevent volatile organic
chemicals from evaporating into the air.
STATE OFFICES
Connecticut Dept. of Env. Protection
Bureau of Air Management
79 Elm Slreet, PO Box 5066
Hartford, CT 06102-5066
(203) 566-2506
Maine Dept. of Env. Protection
Bureau of Air Quality Control
State House, Station 17
Augusta, ME 04333
(207) 287-2437
New Hampshire Dept. of Env. Services
Air Resources Division
64 N, Main Street
Concord, NH 03302-2033
(603) 271-1370
Pennsylvania Dept, of Env. Resources
Market Street Office Building, 12th Floor
PO Box 8468
Harraburg, PA 17105-8468
(717) 787-9702
Commonwealth of Virginia
DepL of Environmental Quality
PO Box 10009
Richmond, VA 23240
(804) 786-2378
FOR MORE INFORMATION
Dept. of Natural Resources and Env. Control
Division of Air and Waste Management
89 Kings Highway, PO Box 1401
Dover, DE 19903
(302) 739-4791
Maryland Dept. of the Environment
Air Management Administration
2500 Broening Highway
Baltimore, MD 21224
(410) 631-3255
New Jersey Dept. of Env. Protection
Division of Env. Quality Air Program
401 East State Street
Trenton, NJ 08625
(609) 292-6710
Rhode Island Dept. of Env. Management
Division of Air and Hazardous Materials
291 Promenade Street
Providence, RI 02908-5767
(401) 277-2808
Ozone Transport Commission
444 North Capital Street, NW
Suite 604
Washington DC, 20001
(202) 508-3840
Air Resources Management Division
2100 Martin Luther King Ave., SE
Washington. DC 20020
(202)404-1180
Massachusetts Dept. of Env. Protection
Division of Air Quality Control
One Winter Street, 7th Floor
Boston, MA 02108
(617)292-5593
New York Dept. of Env. Conservation
Division of Air Resources
50 Wolf Road
Albany, NY 12223-3250
(518) 457-7230
Vermont Agency of Natural Resources
Air Pollution Control Division
103 South Main Street, Building 3 South
Waterbury, VT 05676
(802) 241-3840
Also contact the EPA Stratospheric Ozone Hotline: 1-800-296-1996
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