<< Chapter < Page Chapter >> Page >
Suggested Time: 65 minutes. Science TEKS: 3.11, 4.6, 5.1, 5.2, 5.3, 5.4, 5.5. Math TEKS: 5.11, 5.14, 5.15

Objective

Students have already learned about the most common gases in the atmosphere. Now they will begin to learn about how other substances in the atmosphere can strongly affect their health and the environment, even in minute concentrations. In this lesson, students will learn about stratospheric ozone and the difference between this high-level ozone (which protects the Earth from ultraviolet radiation) and low-level ozone (which is an air pollutant).

Stratospheric ozone forms naturally and protects us from ultraviolet radiation. Tropospheric ozone forms from air pollutant emissions and harms human health.Credit: U.S. EPA: “Ozone Good Up High, Bad Nearby”

Background information

Most of the oxygen in the atmosphere, and the type that we need to sustain life, has two atoms per molecule (O2). Ozone , by contrast, has three oxygen atoms (O3). Ozone forms naturally in the stratosphere when intense ultraviolet radiation from the Sun splits an oxygen molecule (O2) into two O atoms. Each O can then combine with another O2 to form O3. [Note: The concept of molecules composed of atoms is above the 5th grade level; for your explanation to students, you can state that the Sun’s intense UV radiation splits oxygen to form ozone].

About 90 percent of the ozone in the Earth’s atmosphere is found in what is known as the ozone layer in the stratosphere (about 10-30 miles above Earth’s surface). The ozone layer absorbs most of the Sun’s ultraviolet radiation to shield us from these damaging rays. Ultraviolet rays can cause a range of negative effects: they can cause cancer, burn skin, damage eyes, weaken the human immune system, and harm both plants and animals. In fact, estimates show that a one percent reduction in the ozone layer results in a two to five percent increase in the number of cases of cancer!

Certain air pollutants can damage the ozone layer. The most dramatic depletion of the ozone layer is the Antarctic ozone hole . In the early 1980s, scientists discovered major thinning of the ozone layer above Antarctica during springtime . In fact, they observed nearly 70% less ozone than had been found there previously! Scientists realized that the depletion of the ozone layer is caused by the release of certain chemicals such as chlorofluorocarbons (CFCs) into the atmosphere. Just a few decades ago, CFCs were used in air conditioners, aerosol sprays, and cleaning products. When CFCs reach the stratosphere, they react with the sunlight to release chlorine atoms, which can destroy ozone molecules. In 1989, an international agreement known as the Montreal Protocol was signed to ban the most destructive ozone-depleting gases and preserve the ozone layer. If the agreement is adhered to, it is hoped that the ozone layer will completely recover by 2050.

From September 21-30, 2006 the average area of the ozone hole was the largest ever observed. In this image, from Sept. 24, 2006, the Antarctic ozone hole was equal to the record single-day size of 11.4 million square miles.Credit: http://www.nasa.gov/centers/goddard/news/topstory/2006/ozone_record.html

Questions & Answers

what is mutation
Janga Reply
what is a cell
Sifune Reply
how is urine form
Sifune
what is antagonism?
mahase Reply
classification of plants, gymnosperm features.
Linsy Reply
what is the features of gymnosperm
Linsy
how many types of solid did we have
Samuel Reply
what is an ionic bond
Samuel
What is Atoms
Daprince Reply
what is fallopian tube
Merolyn
what is bladder
Merolyn
what's bulbourethral gland
Eduek Reply
urine is formed in the nephron of the renal medulla in the kidney. It starts from filtration, then selective reabsorption and finally secretion
onuoha Reply
State the evolution relation and relevance between endoplasmic reticulum and cytoskeleton as it relates to cell.
Jeremiah
what is heart
Konadu Reply
how is urine formed in human
Konadu
how is urine formed in human
Rahma
what is the diference between a cavity and a canal
Pelagie Reply
what is the causative agent of malaria
Diamond
malaria is caused by an insect called mosquito.
Naomi
Malaria is cause by female anopheles mosquito
Isaac
Malaria is caused by plasmodium Female anopheles mosquitoe is d carrier
Olalekan
a canal is more needed in a root but a cavity is a bad effect
Commander
what are pathogens
Don Reply
In biology, a pathogen (Greek: πάθος pathos "suffering", "passion" and -γενής -genēs "producer of") in the oldest and broadest sense, is anything that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ. The term pathogen came into use in the 1880s.[1][2
Zainab
A virus
Commander
Definition of respiration
Muhsin Reply
respiration is the process in which we breath in oxygen and breath out carbon dioxide
Achor
how are lungs work
Commander
where does digestion begins
Achiri Reply
in the mouth
EZEKIEL
what are the functions of follicle stimulating harmones?
Rashima Reply
stimulates the follicle to release the mature ovum into the oviduct
Davonte
what are the functions of Endocrine and pituitary gland
Chinaza
endocrine secrete hormone and regulate body process
Achor
while pituitary gland is an example of endocrine system and it's found in the Brain
Achor
what's biology?
Egbodo Reply
Biology is the study of living organisms, divided into many specialized field that cover their morphology, physiology,anatomy, behaviour,origin and distribution.
Lisah
biology is the study of life.
Alfreda
Biology is the study of how living organisms live and survive in a specific environment
Sifune
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Rice air curriculum. OpenStax CNX. May 09, 2010 Download for free at http://cnx.org/content/col11200/1.1
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Rice air curriculum' conversation and receive update notifications?

Ask