Ozone ( Environmental Chemistry )

Ozone: It is a molecule consisting of three oxygen atoms i.e. O₃. It is present in stratosphere.

Ozone is formed when u-v rays in upper atmosphere split oxygen atoms that are: –

When oxygen molecule splits into atoms then each atom combine with undissociated molecule of oxygen to form ozone.

Ozone protect us from ultra violet radiations as it doesn’t allow ultra violet rays to enter earth’s atmosphere that if enter into earth may harm us in many ways such as:

• They may raise the temperature of earth
• It can cause global warming
• It may cause skin disorders, eye disorders and many more.
• The thinning of ozone layer by air pollutants is called ozone depletion.

For this some synthetic chemicals are responsible like ChloroFloro Carbons that are used in refrigerators, air conditioners, etc.

Ozone hole

• Due to continuous use of certain harmful chemicals like CFC’s etc. they have caused thinning of ozone layer to an extent that a hole is observed in ozone layer in the region of Antarctica.
• This hole is not a hole actually we can say it is the extreme thinning in some parts due to extreme reactions taking place with certain harmful chemicals that are not stable in upper atmosphere and react with ozone causing its depletion

 Montreal protocol:

•  It is agreement made by industrialized nations to freeze the production of CFC’s and make use of some alternative source.
• It was done in 1987 UNEP (United Nations Environment Program)

Now, instead of using CFC’s; HFC’S and PFC’s are used that is somehow helping in saving the ozone layer.

Particulate pollutants

• They are minute solid or liquid particles present in air.These are released by vehicle exhaust, dust and ashes of hydrocarbons.
• They may be viable like bacteria etc. and non-viable like ash etc.

Non-viable particulates are classified according to nature and size of particles. They are as follows:-

Smoke: Itconsists of solid and liquid particles formed during combustion of fuels etc.

Dust: It is composed of fine solid particles produced during crushing, grinding of solid particles, like saw dust from wood, fly ash from factories etc.

Mist:They are produced by particles of spray liquids and condensation of vapors in air, like insecticides etc.

Fumes:They are obtained by condensation of vapors during sublimation, distillation, boilingetc., like metallic and non-metallic oxides

• The particulate matter harm but degree of harm depends upon the size of particles particulate pollutants bigger than 5 microns can block nasal passage whereas particle of size micron can even enter lungs.