The document discusses the ozone layer, its importance in protecting life on Earth from UV radiation, and threats to its stability. It notes that the ozone layer forms 15-50 km above the ground and is made up of ozone molecules containing three oxygen atoms. It protects the atmosphere by absorbing UV radiation. However, CFC gases released into the air are damaging the ozone layer and causing it to thin, especially over Antarctica where a large ozone hole has formed. As the ozone layer thins, more dangerous UV radiation reaches the Earth's surface, increasing health risks like skin cancer. Actions to reduce CFC emissions have helped stop further ozone layer depletion, and it is expected to recover by 2050.

1. Emma Hedman

2. * In the atmosphere we have a layer, 15 to 50 kilometers
above ground, this is called the ozone layer. Without this
layer life would not exist on our planet.
* Ozone is another form of oxygen but apart from the air
that we breath, that has two oxygen atoms, the ozone
molecules has three.
* The ozone layer prevents the UV radiation to brake in to
the atmosphere. Today the ozone in the stratosphere is
reduced and this affects the life on our planet.
Oxygen

3. * Before we got life on our planet, it probably not existed
any oxygen in the atmosphere. It was after plants who
produced oxygen by the photosynthesis started
growing, the oxygen and by that the ozone started to form.
* Ozone forms when the oxygen molecules cleaves by the UV
radiation. The single oxygen atom that is flying around pair
up with another oxygen molecule and by that becomes
ozone.
* These ozone molecules form a layer in the sky that is
protecting us from the UV radiation.

4. * The ozone layer is thinning because of the large
amount of gases we are letting out in the
atmosphere.
* The biggest problem is the Freon or CFCs gases.
These are dangerous gases for the ozone layer
because they are breaking them down and the
ozone layer gets thinner.
* The thinning is called ozone hole.
* In the Antarctic, we have encountered the biggest
ozone hole in history. This I because of the cold
winters and the air circulation that is very stable.

5. * The UV radiation is getting more dangerous when
more of it can get through the ozone layer.
* The UV radiation is what makes us tanned in the
summers and gives the skin D-vitamins. But it is also
bad for our skin, molecules like DNA and protein is
absorbing this radiation and get damage of it.
* When bigger amounts of UV radiation reach earth
the damage is bigger. The risk of getting skin cancer
is bigger and you can also get cataracts.

6. * Faster than in any other environmental area, we have
collaborated to make this better.
* In the developed countries we have stopped the
production of Freon and CFC gases while the under
developed countries have got a little longer time to do
this.
* Because of this, the ozone thinning has stopped and start
recovering. It should be recovered in 2050!

7. http://www.ne.se/enkel/ozonskiktet
http://www.nasa.gov/home/index.html