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The Annual Conservation Video Contest

The Ozone Layer

What is the Ozone Layer?

The Ozone Layer is a layer of gas designed to block out some of the sun's harmful rays. You have heard of UV-A and UV-B rays (they're written all over sun screen bottles), well, the Ozone Layer is like built-in sun screen for the whole Earth. Just like you get a burn if you don't keep re-applying sun screen all day long, the Earth gets burned when the Ozone Layer breaks down. It's like taking away the Earth's sun screen!

Have you noticed the change: Sun tan lotion to sun screen?
A tan just isn't cool anymore!

What's wrong with the Ozone Layer?

There are a couple of holes in the ozone layer. One of these holes is directly over Antarctica and the other hole is over the Arctic on the Asian side. The hole over Antarctica was discovered in 1985. It was found to cover 20 million km2. For comparison, Canada is only 9.9 million km2.

That is a HUGE hole!

Where is the ozone layer?

The ozone layer lies between 10 and 50 kilometres above the Earth's surface. It is in a region of the atmosphere called the Stratosphere. The Stratosphere completely surrounds the Earth with a thickness of about 33 kilometers in most places.

What are the chemicals that cause the breakdown of ozone?

The key chemicals responsible for the hole in the Ozone Layer are chlorofluorocarbons (CFC's), although the following chemicals are also involved:

CFC's are present in old air conditioners, refrigerators, foam packages, and aerosols. These products no longer include CFC's, as their production was phased out in January of 1996. If you have an old fridge or air conditioner that you or your parents are throwing out, make sure that you find out where you can have the CFC's removed without releasing them into the atmosphere. The problem is caused by the chlorine that is present in the CFC molecule. The chlorine actually attaches to single oxygen atoms that SHOULD be going to form ozone molecules......READ ON!

What causes the Ozone Layer to break down?

There are many human-made chemicals that interfere with the formation of the ozone layer. The ozone layer isn't like a blanket or a sheet on your bed. It isn't always the same. It is always breaking up and reforming.

Ozone is made up of 3 oxygen atoms. It is like the oxygen gas that we breath, only with an extra oxygen:

1 oxygen atom:


1 oxygen molecule:


(this is what we breathe)

1 ozone molecule:


The sun's energy breaks up oxygen molecules (O2) and ozone molecules (O3) to form single oxygen atoms (O). The "O" then combines with another "O2" to form ozone (O3). Ozone is then broken up again into an "O" and an "O2" (again by the sun) and the whole cycle begins again.

The BIG problem is that chemicals (like CFC's) interfere with this cycle. When CFC's reach the stratosphere, the sun's rays cause them to release a chlorine atom. Then, when the ozone molecule is split into "O" and "O2" , the Chlorine jumps in and grabs the "O" forming "ClO" (Chlorine Monoxide). When the "ClO" meets up with another "O", the "Cl" hops off and "O2" forms. So, what remains is lots of "O2" and hardly any ozone. Not only that, but the same chlorine atom can keep stealing more "O" so that ozone can no longer form.

What is being done about the hole in the Ozone Layer?

When the first hole in the Ozone Layer was discovered in 1985, everyone was shocked. So, in 1987 there was a big meeting in Montreal to try and decide what should be done about "the surprise hole".

The Montreal Protocol:

The Montreal Protocol set up "rules" for the use of chlorofluorocarbons (CFC's). It stated that all manufacturing of CFC's should be stopped by 1996 in industrialized countries, such as Canada.

How Montreal made a difference:

Since 1987, ozone depleting substances (ODS) have dropped in concentration from 27.8 kilotonnes to 1 kilotonne (1996). To give you an idea of the amount of mass this is, 27.8 kilotonnes is how much 6000 Elephants would weigh! Although CFC's are down by 85% globally, there are still plenty in the stratosphere that continue to break down the ozone layer because CFC's can stay around for at least 100 years. When all of the countries started working together, a difference was made, starting a chain reaction. We need to keep it going - the results will be miraculous!

How does Ozone Layer depletion effect Climate Change?

The hole in the ozone layer is not directly a cause or effect of Climate Change. However, the same gases that cause the hole to form in the Ozone Layer are also Greenhouse Gases! Another consideration is that since the hole in the Ozone Layer allows more UV rays to reach the Earth, perhaps it is leading to the presence of more heating infrared rays. What do you think?

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