![earth under umbrella](/web/20061209185326im_/http://www.ec.gc.ca/ozone/DOCS/KIDZONE/images/earth-umbrella.gif) |
What's
Going On
Up There? |
A GIANT UMBRELLA OVER THE EARTH
|
You have probably heard
people talk about a "hole" in our ozone layer. Damage to our Earth's giant
protective umbrella is more severe in the South Pole, but, even there, no actual
"hole" exists. And only a slight thinning occurs over the rest of the world. So
no matter where you stand, you won't find a true "hole".
About 20 kilometres thick, this giant umbrella is made up of a layer of ozone gas. This gas is
found some 15 to 35 kilometres above the Earth's surface in the upper atmosphere or
"stratosphere". |
Like a good pair of sunglasses, the ozone layer acts like a natural filter,
blocking out most of the sun's harmful UV (ultraviolet) rays. Without the ozone layer,
more people would get sunburns, skin cancer and cataracts. Plants and animals would also
be affected. So we can think of the ozone layer as our planet's own protective sunscreen.
Did You Know?
If the ozone layer were brought down to the Earth's surface, air pressure and
temperature conditions would compress the ozone into a layer 2 to 5 mm thick! |
Fact:
Ozone (O3) has three atoms of oxygen. The form of oxygen be breathe (O2) has two oxygen atoms. |
Sniff, sniff
If you have ever noticed the "sharp" clean smell after a thunderstorm
or the "electric" smell of a subway train, then you've smelled a bit of ozone
gas. In larger amounts, ozone is unpleasant with a strong odour that irritates the eyes
and lungs.
Good and Bad Ozone
The ozone layer contains almost all the ozone gas that exists. This is "good"
ozone because it protects us from the sun's UV rays. At ground level we find
"bad" ozone, as a result of emissions from car exhaust, for example. During the
summer it causes smog in large cities.
Unfortunately, ground level ozone is increasing while stratospheric ozone decreases. We
cannot move the lower ozone gas up to help the ozone layer. The best solution is to
continue to reduce all sources of pollution affecting our atmosphere.
Important Scientific Discoveries!
In 1985, British scientists found an ozone "hole" or large thin area over the
Antarctic. After this discovery, Canadian scientists looked for ozone thinning in the
Arctic. They found that the ozone damage over the Arctic was much less severe than the
damage over the South Pole and that there was little increased risk to people living in
the far north.
Even though the ozone layer is an invisible shield, scientists have found a number of
ways to measure it; one way is to use helium-filled balloons that carry measuring
instruments into the atmosphere and transmit information back to Earth. Environment Canada
has also invented a very sensitive instrument that takes ozone layer measurements from the
ground.
Did You Know?
Our own astronaut, Steve Maclean, used a Canadian-made instrument on a recent U.S.
space shuttle mission to measure the ozone layer from space! |
What are CFCs?
CFCs and other ozone-depleting chemicals were first mass-produced in the 1950s for use as
refrigerants, industrial solvents, cleaning fluids and agents in making foam products. In
the late 1960s, they were widely used in spray cans. In 1980, Canada and other countries
banned CFC use in aerosol sprays.
Fact :
Scientists
have shown that certain chemicals are slowly eroding the ozone layer. The main culprits
are chlorofluorocarbons or CFCs. |
Although CFCs do not harm the environment near the ground, they slowly travel upwards
to the ozone layer where they are broken down by UV light into chlorine atoms. Here, the
chlorine atoms eat away at the ozone like pac-men.
Did you know?
If all ozone-depleting chemicals were successfully phased out, the ozone layer
would eventually heal itself. |
What's being done?
Canada and nations from around the world have agreed to stop using CFCs by 1996. In
Canada, governments are also starting programs to recycle and recover CFCs.
It takes time before ozone-depleting chemicals can be totally eliminated. First,
industries must develop harmless ways to replace the CFCs we use for important purposes
like refrigeration. Also, some countries do not have the means to use substitutes. So a
special fund has been set up to help these nations use new chemicals and technology.
We can see that a thinning ozone layer is a global problem that will only be solved
with the co- operation of every country in the world.
How can you help?
We have an important role to play in protecting the ozone layer. Together, we
can take action by phasing CFCs and other ozone-depleting chemicals out of our lives.
In Canada, CFCs have been removed from spray cans and food packaging foam (egg cartons,
foam cups, meat trays, etc.).
Until substitutes are found CFCs will still be used in refrigeration. In the meantime,
make sure your freezers and refrigerators are carefully serviced, and that CFCs are
recovered and recycled rather than just replaced.
Avoid installing CFC-dependent air conditioning systems in your car. Use alternatives
such as cardboard window screens to cool your parked car. If you have car air
conditioning, make sure it is properly maintained and that the CFCs are recycled and
recovered when serviced.
UV and You
The ozone layer screens out most of the sun's harmful UV (ultraviolet) rays. Our tans and
sunburns are caused by UV. UV is a natural part of the sun's rays, but it has always been
harmful.
With the thinning of the ozone layer, the amount of UV reaching us has slightly
increased. This small increase doesn't mean we can't enjoy the outdoors, but we should
always take precautions.
Fact:
We don't need a tan to be healthy. Protect your skin from the sun:
Spend less time in the sun, especially when your shadow is shorter than you! Cover up!
Wear a hat, long-sleeved shirt and long pants. Use a sunscreen SPF 15 or greater. |
Tune in!
During the summer months, Environment Canada issues the UV Index as part of your daily
weather forecast. Listen for it on the radio or TV, check the newspaper, or contact your
local weather office.
Test your knowledge!
a. Stratosphere |
|
1. What do we call the Earth's giant protective
umbrella? |
b. Refrigerators |
|
2. What is another name for the sun's harmful rays? |
c. Look for shade! |
|
3. In which part of the atmosphere is the ozone layer
located? |
d. UV (ultraviolet) |
|
4. Find a chemical that harms the ozone layer. |
e. CFCs |
|
5. Find one example of where CFCs are used. |
f. Recycle CFCs! |
|
6. What are two effects of a thinning ozone layer? |
g. Crop damage |
|
7. What can you do to protect the ozone layer? |
h. Sunburn |
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8. How can you protect yourself against the sun's
harmful rays? |
i. Ozone layer |
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Be an environmental citizen -
help protect the ozone layer! |
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