- Ozone or trioxygen has the chemical formula of O3. It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is less stable than the diatomic allotrope, O2.
- In the lower atmosphere, it breaks down into O2. Ozone is formed from dioxygen by the action of ultraviolet (UV) light and also due to atmospheric electrical discharges.
- It is present in low concentrations throughout the earth’s atmosphere (stratosphere).
- Ozone is a powerful oxidant (more than dioxygen) and has many industrial applications. When the ozone levels reach about 100 ppb (parts per billion) in the lower atmosphere, then it becomes a potent respiratory hazard and pollutant.
- However, the ozone layer (a portion of the stratosphere with a higher concentration of ozone, about 2-8 ppm) is beneficial, preventing the UV light from reaching the earth’s surface, for the benefit of both plants and animals. OZONE DEPLETION
Harmful Consequences of UV Rays
If there is an absence of ozone layer, then the UV rays will reach the earth in significant amount and can have the following negative consequences:
- Tanning and ageing of skin.
- Skin cancer.
- Lower the functioning of immune system.
- Damage the genetic material namely, DNA.
- Causes fading of clothes.
- Make plastics brittle. OZONE DEPLETION
Ozone (O3) protects oxygen at lower altitudes from being broken down by the action of UV rays. In case of absence of ozone layer, life cannot exist on earth.
Measurement of Ozone
- The most common instrument for measuring ozone thickness is Dobson Spectrophotometre.
- The abundance of ozone is given in Dobson unit named after the physicist, Gordon Dobson.
- Dobson unit reflects the thickness of the ozone column. OZONE DEPLETION