AIR POLLUTION AND TERMINOLOGY INVOLVED IN AIR POLLUTION

INTRODUCTION

Air pollution is defined as the presence of non desirable substances in air in the quantities that are high enough to produce harmful effects.

These non desirable substances cause damage to vegetation, health, property, global environment, aesthetic insults in the form of unpleasant smell of brown or hazy air. Many sources of pollutants in the atmosphere are beyond the control of humans. In most densely populated areas and industrialized countries the main sources of pollution are human activities. These activities are linked with the human living style. Without these activities the standard of living reduced to much lower level. 

Another definition of Air Pollution is:

It is defined as the atmospheric conditions in which certain substances are present in such concentrations that cause harmful effects on man and its environment. These substances are gases, particulates, radioactive materials and others. 

AIR POLLUTANTS

Pollutants are the substances that cause the damage to the target in environment. When these materials are introduced in environment, cause the negative effect on the use of resources.

Air pollutants are categorized as physical, biological, chemical an radioactive materials that make the air unhealthy for breathing. 

1) Primary Pollutants

The pollutants that are directly emitted by terrestrial sources are known as primary pollutants.

Examples of primary pollutants are:

• Carbon Monoxide                         
• Carbon Dioxide
• Sulphur Dioxide
• Ammonia
• Nitric Oxide
• Hydrogen Sulphide
• Nitric Oxide
• Hydrogen Fluoride
• Particulates such as dust, ash, fumes, smoke, radioactive substances and hydrocarbons

2) Secondary Pollutants

From the chemical and photochemical interactions between primary pollutants or atmospheric components secondary pollutants are made.

Examples of secondary pollutants are:

• Sulphur Trioxide
• Nitrogen Dioxide
• Sulphates
• Nitrates
• Ozone
• Aldehydes
• PAN (Peroxy Acyl Nitrate)

Secondary pollutants depends upon topographic and meteorological conditions and nature and concentration of primary pollutants and atmospheric components. 

COMPOSITION OF AIR

                         GAS                 CONCENTRATIONS (%)             

                         

                             Nitrogen                                           78.1  

                               Oxygen                                           20.9

                               Argon                                             0.93

                               Carbon Dioxide                          0.033

                               Krypton                                 0.000114

                               Methane                                    0.0002

                               Hydrogen                                0.00005

                               Xenon                                  0.0000087

                               Nitrous Oxide                       0.30 ppm

                               Neon                                    18.18 ppm

PROPERTIES OF POLLUTANTS AND POLLUTION SIGNIFICANCE

Carbon Monoxide

It is a colorless and odorless gas. It is formed during incomplete combustion of hydrocarbons. It causes greenhouse effect and climate changes.

Nitrogen Dioxide

It is a brown orange colored gas. It is a component of photochemical smog and acid deposition.

Ozone

It is highly reactive. It is a secondary pollutant and is produced during photochemical smog. It damages flora and materials.

Sulphur Dioxide

It is a colorless choking gas, soluble in water and produce sulphuric acid. It is a component of acid deposition and damage the flora and fauna.

Lead

It is a heavy metal and it is a source of leaded petrol. Lead pipes, incineration, quarrying are made of lead. It damages fauna and humans.