Theme: The Air We Breathe
Learning and Teaching Activities
Discussion on ozone
Teaching tips
Teach students how and where to search the information of the topic. Then ask students to
think them deeply. Also, lead the students to have logical analysis.
The worksheet could be distributed 2-3 days before the activity.
Objective: Understand the nature and toxicity of ozone on human health.
Introduction
The following web sites could be used:
1.
國立臺灣師範大學物理學系黃福坤副教授．國立臺灣師範大學物理學系網頁，物理
教學示範實驗教室，臭氧的好與壞．Web address:
http://www.phy.ntnu.edu.tw/demolab/everydayPhysics/ozone.html. Last modified:
18/01/2002
2.
United States, Environmental Protection Agency (USEPA). Air and Radiation, Air
Quality Planning and Standards, Ozone: Good Up High, Bad Near By. Web address:
http://www.epa.gov/oar/oaqps/gooduphigh/#goodbad. Last updated: 17/08/2002
3.
University of Michigan. Global Change web site, Global Change 1 Physical Processes,
Lecture Schedule, Ozone: The Good, The Bad and The Ugly. Web address:
http://www.globalchange.umich.edu/globalchange1/current/lectures/samson/ozone/
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Ozone, made up of 3 oxygen atoms, is a reactive gas that is involved in many chemical
reactions. The gas could be good or bad to the ecosystem and humans, depending on its
location in the atmosphere (namely: stratosphere and ground level). Scientists have been
investigating the advantages and disadvantages of ozone, and developing advance technology
to employ this gas in pollutant treatments (oxidative degradation of the pollutants) for years.
Students’ work
In this exercise, you are divided into groups (3 – 5 students a group). You have to discuss
whether ozone is good or bad to human and the environment. Try to answer the following
questions:

Ozone in the stratosphere
1.
Ozone is “good” in the stratosphere, could you state the reason(s) for it?
2.
What cause(s) the ozone depletion in the stratosphere? How many types of
manmade pollutants will destroy the ozone layer?
3.
How does the depletion of "Good" ozone affect human health and the
environment?


Ozone in the troposphere (ground level ozone)
1.
What cause the formation of “bad” ozone in troposphere?
2.
How does the “bad” ozone affect the ecosystem and human health?
What can we do?
What actions could individuals take to protect the “good” ozone up high in the
atmosphere, and prevent/ reduce the formation of “bad” ozone in ground level?
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Suggested answers. (Accept alternative and correct answers)

Ozone in the stratosphere
1.
Ozone is “good” in the stratosphere, could you state the reason(s) for it?
The stratospheric ozone layer protects life on earth from the sun's harmful
ultraviolet rays.
2.
What cause(s) the ozone depletion in the stratosphere? How many types of
manmade pollutants will destroy the ozone layer?
Ozone – depleting substances (ODS) destroy the stratosphere ozone layer. Major
manmade pollutants destroying the ozone layer: chlorofluorocarbons (CFCs), halons,
and other ODS (used in coolants, foaming agents, fire extinguishers, and solvents).
3.
How does the depletion of "Good" ozone affect human health and the environment?
Increased UV radiation: lead to more cases of skin cancer, cataracts, and impaired
immune systems. / Damage to UV sensitive crops, such as soybeans, reduces yield. /
Cause decreases in phytoplankton, an important link in the marine food chain and,
therefore, food populations could decline. / As plants utilize carbon dioxide, carbon
dioxide levels in the air could also increase. / Increased UV radiation can be
instrumental in forming more ground-level ozone.

Ozone in the troposphere
1.
What cause the formation of “Bad” ozone in troposphere?
Major sources of NOx and VOC (ozone precursors): motor vehicle exhaust and
industrial emissions, gasoline vapors, and chemical solvents. Strong sunlight and
hot weather cause ground-level ozone to form in harmful concentrations in the air
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through a series of chemical reactions.
2.
How does the “bad” ozone affect the ecosystem and human health?
Inhalation of ground level ozone: triggers different health problems including
chest pains, coughing, nausea, throat irritation and congestion. It also can worsen
bronchitis, heart disease, asthma, and reduce lung capacity. Healthy people also
experience difficulty in breathing when exposed to ozone pollution
Ground-level ozone damages plant life; it interferes with the ability of plants to produce
and store food, making them more susceptible to disease, insects, other pollutants and
harsh weather. "Bad" ozone damages the foliage of trees and other plants, ruining the
landscape of cities, national parks and forests, and recreation areas.

What can we do?
What actions could individuals take to protect the “Good” ozone up high in the
atmosphere, and prevent the formation of “Bad” ozone in ground level?
Stratospheric "Good" Ozone

Have your car and home air conditioner units and refrigerator checked for leaks.
When possible, repair leaky air conditioning units before refilling them.

Contact local authorities to properly dispose of refrigeration or air conditioning
equipment.
Ground-Level "Bad" Ozone
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
Keep your automobile well tuned and maintained.

Use mass transit, walk, bicycle, and reduce driving, especially on hot summer days.

Be careful not to spill gasoline when filling up your car or gasoline-powered lawn
and garden equipment. During the summer, fill your gas tank during the cooler
evening hours.

Participate in your local utility's energy conservation programs.

Seal containers of household cleaners, chemicals and solvents, and garden
chemicals to prevent VOC from evaporating into the air. Dispose them properly
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