1.

Ozón

2.

Freony

3.	Ničení ozónu

4.	Hodnocení budoucnosti

5.	Mezinárodní smlouvy

6.	Použitá literatura

"Destroying of ozone
Rowland and Mobia
Cl + O3 = ClO + O2
ClO + O = Cl + O3

Later theory:
Cl + O3 = ClO + O2
ClO + ClO + M = Cl2O2 + M
Cl2O2 + hv = Cl + ClO2
ClO2 + M = Cl + O2 + M

Chlorine needs stratosphere clouds for destroying ozone. They can be found above poles. That’s why the concentration of Cl* so high above poles.
The lowest ozone layer was measured in years 1993 and 1994 above South pole. Ozone layer had just 90 d.u., that’s only 40% of normal state. When ozone layer drops under 50% of its typical state, it’s supposed to be an ozone layer.
In years 1926 - 1969 there was slight increase of ozone layer by 0.19% every 10 years. But during the years 70-90 ozone dramatically decreased by 2.5% every ten years. Moreover, there was much higher decrease in 1990’s.

Future evaluation
In 1970’s emissions of freons raised by 10% every year. It would have caused 30% reduction of ozone layer by the year 2000. Now the forecast is better, because there was a reduction in use of CFC-11 and CFC-12 and the emissions in 1995 dropped to the level of year 1976.
There are two prognoses for the future:
1) If the emissions of CFC will be constant on the level of year 19976, there is going to be reduction of ozone by 2% until year 2000, by 3-4% until year 2080 and about 4% until 2100. In the further future, the decrease would be about 6%.
2) The second prognoses suppose better knowledge of Chemistry over the time and reduction of using freons. The minimum level of ozone would be reached in year 2000, then there wouldn’t be big changes for 10 to 20 years and the ozone layer should reach it’s original level in the second half of the 21st century or at the end of the 21st century.
In the year 2015, it’s supposed to be in use about 500 stratosphere airplanes, each for 300 passengers. The damage of ozone layer should vary from 0.25% up to 7%, which is much lower than by freons

International contracts
1) On the conference of United Nations Environment Programme was signed Vienna’s contract about protection of ozone layer on March 22nd 1985. 135 countries signed this contract.
2) Montreal protocol about compounds distracting ozone layer was accepted on September16 1987. It’s protocol for Vienna’s contract. 148 countries signed it.
3) London’s clause - June 26th - 29th 1990. The list of CFC compounds was expanded from 5 to 15 and the year, by which they should be completely prohibited, was set to 2000. 180 countries signed.
4) Other clause of Montreal protocol was accepted in 1991 in Nairobi
5) Kodan’s clause - CFC shouldn’t be made after January 1st 1996 and halons shouldn’t be made after January 1st 1994. 37 countries signed this clause."