Ozone Layer Depletion

Ozone Layer Depletion

• Ozone (O₃) is a gas found in atmosphere. Ozone is highly concentrated in stratosphere which lies about 15 - 50 km above the earth's surface. This is known as ozone layer.

• The ozone in stratosphere protects living organisms from the ultraviolet radiation of the sun. In particular, it absorbs ultraviolet (UV) radiations and screens out harmful UV radiations.

1. Hole in Ozone Layer

• The amount of ozone present in atmosphere is delicate balance between the maning and destruction of ozone that depends upon the existence of naturally occuring trace compound.

• If some unnatural compounds are added to this balance that can provide extra catalytic species, then the destruction of ozone will be enhanced. This situation is known as hole in the ozone layer or depletion of ozone layer.

2. Ozone Depleting Substances

• Ozone layer is very much destroyed by the catalytic reactions having free radicals such as clorine (Cl), bromin (Br), hydrogen (H) and nitric oxide (NO).

• Following gases causes depletion of ozone in atmosphere

3. Impact of Ozone Layer Depletion

• Effect / impact or consequences of ozone layer depletion are :

1. Effects on human health

UV rays damage genetic material in skin causing skin cancer.

Prolonged exposure to UV rays may cause blindness.

Human resistivity is reduced resulting in allergies and infections.

2. Effects on aquatic system

Kills lower fauna and flora

Affects photosynthesis process cause mutation.

3. Effect on materials

Degradation of point quality and plastics.

4. Effects on climate

Climate change.

Global warming.

4. Measurement of Ozone / Dobson Unit

• The amount of atmospheric ozone is measured by "Dobson spectrometer" and is expressed in Dobson Units (DU).

• One Dobson Unit (1 DU) is equivalent to 0.01 mm thickness of pure ozone at the density is poses it is brought to ground level (1 atm) pressure.

• In temperature latidue concentration of ozone is 350 DU and in tropics it is 250 DU.

5. Control Measures for Depletion of Ozone Layer

1. Reducing CFCs and other ozone depleting chemicals.

2. To make serious efforts to produce and propagate the use of alternative chemicals which do not deplet ozone in stratosphere.