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What Are the Causes of Ozone Depletion?

This article presents an overview of the causes of ozone depletion. Learn about the chemicals that are responsible for ozone depletion.

The ozone layer is a portion of the atmosphere that absorbs ultraviolet radiation. Ozone is the molecule responsible for this. Its structure consists of three oxygen atoms, or O3, which is one more than the normal oxygen molecule (O2) found in air. The concentration of ozone in the atmosphere is naturally low, and over time, the ozone layer has become even smaller. Several studies were conducted to find out why the ozone layer was shrinking. Most have concluded that the causes of ozone depletion should include the introduction of chemicals into the atmosphere.

Chlorofluorocarbons (CFCs)

One group of chemicals responsible for the depletion of the ozone layer is the chlorofluorocarbons. It is believed that this group of chemicals is responsible for about 80% of the damage to the ozone layer. This chemical was uses in coolants for air conditioners and refrigerators manufactured before 1995.

Hydrofluorocarbons (HCFCs)

CFCs were replaced by another group of chemicals called hydrofluorocarbons. Thee chemicals were less destructive to the ozone layer, but they still reduced the concentration of ozone in the atmosphere. HCFCs are very potent greenhouse gases.

Halons

Another group of chemicals which affect the ozone layer is the halons. This type of chemical was commonly used in some types of fire extinguishers.

Methyl Chloroform

Methyl chloroform is another chemical that damages the ozone layer. It is commonly used for industrial applications including vapor degreasing and chemical processing.

Carbon Tetrachloride

Some types of solvents and certain compounds in fire extinguishers may contain carbon tetrachloride. This chemical negatively affects ozone.

How Ozone is Affected By These Chemicals?

Primarily, it is the chlorine atoms in CFCs and bromine atoms in halons that damage ozone. These atoms are dislodged via ultraviolet light and react with ozone (O3). The result is an oxygen molecule (O2) and an intermediate molecule, such as chlorine monoxide. Chlorine monoxide in turn reacts with a free oxygen atom (O) to produce an oxygen molecule (O2) and a lone chlorine atom. The chlorine atom repeats the process by reacting with another ozone molecule.


Reference:

The Causes of Ozone Depletion – BC Air Quality

Sharon Beder. The Hole Story – University of Wollongong

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