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Key Facts about Ozone Layer   

About 20 Kilometers thick, this giant umbrella is made up of a layer of ozone gas. This gas is found some 15 to 35 kilometers above the Earth's surface in the upper atmosphere or "stratosphere".


Although ozone (O3) is present in small concentrations throughout the atmosphere, most ozone (about 90%) exists in the stratosphere, in a layer between 10 and 50km above the surface of the earth. This ozone layer performs the essential task of filtering out most of the sun's biologically harmful ultraviolet (UV-B) radiation. Concentrations of ozone in the atmosphere vary naturally according to temperature, weather, latitude and altitude. Furthermore, aerosols and other particles ejected by natural events such as volcanic eruptions can have measurable impacts on ozone levels.


 If the ozone layer was brought down to the Earth's surface, air pressure and temperature conditions would compress the ozone into a layer 2 to 5 mm thick!


What Is Stratospheric Ozone?


Ozone is a natural gas that is found in two different layers of the atmosphere. In the layer around the Earth's surface (the troposphere) ground-level, or bad ozone dirties the air and helps make smog. The troposphere extends up to the stratosphere layer, where good ozone protects life on Earth by absorbing some of the sun's UV rays. Stratospheric ozone is found most often between six to 30 miles above the Earth's surface.


Ozone Depletion


Recently, chlorofluorocarbons (CFCs) were used a lot in industry and elsewhere to keep things cold, make foam, and soaps. Strong winds carry CFCs into the stratosphere. This can take two to five years. When CFCs break down in the stratosphere, they release chlorine. Each chlorine atom attacks ozone by joining with and breaking apart as many as 100,000 ozone molecules during the time it is in the stratosphere.


Other ozone eating chemicals are pesticides such as methyl bromide, halons used in fire extinguishers, and methyl chloroform used in businesses. If all ozone-depleting chemicals were successfully phased out, the ozone layer would eventually heal itself.


The Ozone Hole


In 1985, scientists identified a thinning of the ozone layer over the Antarctic during the spring months which became known as the "ozone hole". The scientific evidence shows that human-made chemicals are responsible for the creation of the Antarctic ozone hole and are also likely to play a role in global ozone losses


 

What you can do to protect the Ozone Layer


Try to find out as much as you can about the problem from publications, schools or public libraries. The only way to mend the ozone hole is to stop the release of CFCs and other ozone depleting substances (ODS) into the atmosphere. European legislation aims to achieve this by phasing out ODS as soon as viable alternatives become available, and where no such alternatives are available, restricting the use of these substances as far as possible. However, there are a number of practical initiatives which can be taken at the individual level to help protect the ozone layer:


·         Try to use products which are labelled "Ozone-Friendly"


·         Ensure technicians repairing your refrigerator or air conditioner recover and recycle the old CFCs so they are not released into the atmosphere.


·         Vehicle air conditioning units should regularly be checked for leaks.


·         Ask about converting your car to a substitute refrigerant if the a/c system needs major repair


·         Help start a refrigerant recovery and recycling program in your area if none already exists.


·         Replace halon fire extinguishers with alternatives (e.g. carbon dioxide or foam).


·         Suggest school activities to increase awareness of the problem and to initiate local action.
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