What is Ozone? Explain its significance

Ozone

• Typically, an oxygen molecule which we breathe in every day is made of two oxygen atoms (O2 showing two oxygen atoms). 
• However, ozone, which is also a molecule containing oxygen, contains three oxygen atoms instead (O3).
• Oxygen (O2) makes up 21% of the Earth’s atmosphere, and ozone makes up less than 0.001%.

Production

• Ozone molecules are created by the interaction of ultra-violet (UV) radiation from the Sun with O2 molecules.
• An O2 molecule is split, the two free oxygen atoms bond with other O2 molecules to form O3 molecules.

Ozone layer

• Because UV radiation is more intense at higher altitudes where the air is thinner, it is in the stratosphere where most of the ozone is produced, giving rise to what is called the ‘ozone layer’.
• The ozone layer extends between about 10 and 40km altitude, peaking at about 25km.

Significance

• The ozone layer is very important for life on Earth because it has the property of absorbing the most damaging form of UV radiation, UV-B radiation.
• This has a wavelength of between 280 and 315 nanometers.
• Most skin cancers are caused by exposure to high amounts of UV radiation, so anything that shields us from UV rays helps reduce cancer rates.
• As UV radiation is absorbed by ozone in the stratosphere, it heats up the surrounding air to produce the stratospheric temperature inversion.

Measuring stratospheric ozone

• Ozone is measured as the total amount that is present in a column of overlying atmosphere in Dobson units.
• One Dobson unit can be thought of as the amount of ozone that would be present if it formed a layer 0.01mm thick at average sea-level pressure and temperature.

Ozone-layer-depletion