Air Pollution

Air Pollution may be defined as the presence of impurities in excessive quantity and duration to cause adverse effects on plants,animals,human beings and materials.

Air Pollution from automobiles,industrial plants,coal burning power plants,incinerators,and furnaces have created serious environmental pollution problems


Sources of air pollution

The two main sources of air pollution are

a)Natural Sources

b)Man made or anthropogenic sources

Natural sources include dust,storms,volcanoes,lightening,sea salt,smoke,forest fires,etc.The man made sources are agricultural activities,industrial growth,domestic wastes,automobile exhausts,etc.


Types of Air Pollutants


Air Pollutants are generally grouped into the following two types.

a)Particulate Pollutants and
b)Gaseous Pollutants

a)Particulate Pollutants:In general the term 'Particulate'refers to all atmospheric substances that are not gases.They can be suspended droplets or solid particles or mixtures of the two.Particulates can be composed of materials ranging in size from 100 micrometers to 0.1 micrometers.

Dust,Smoke,Fumes,Fog,Mist,Aerosol are the classification of particulates.

2)Gaseous Pollutants:

These are toxic and poisonous gases such as carbon monoxide,chlorine,ammonia,hydrogen sulphates, sulphur dioxide,nitrogen oxides and carbon dioxide.

Effects of Air Pollution:

The effects of air pollution are listed below.

1.Effect of air pollution on human health:

aa)The effect of air pollutants on materials:

Effect on materials :: Responsible Air Pollutants

a)Discoloration and deterioration of limestone and building materials :: NO,CO₂,acids and aerosols

b)Reduction in tensile strength of textiles :: SO₂,acid and gases

c)Cracking and strength loss of rubber :: O₃,Oxidants

ab)Effects of air pollutants on vegetation:

Pollutant :: Effects on Vegetation

a)SO₂ :: Chlorosis

b)NO₂ :: Premature fall of leaves and suppressed growth of plants and seduced yield

c)Ozone :: Necrosis(Dead areas on leaves),leaf damages and reduced yield.

2.Effects on Animals:

Animals take up fluorides of air through plants.Their milk production falls and their teeth and bones are affected.They are also prone to lead poisoning and paralysis

3.Effects on Physical properties of Atmosphere

Some of the effects of air pollution on physical properties of atmosphere are

a)Impact of Air Pollution on Health

b)Carbon monoxide(CO)

c)Nitrogen Oxides

d)Hydrocarbons(HC)

e)Benzene(C₆H₆)

f)Lead(Pb

g)Suspended Particulate Matter(SPM)

h)Sulfur Dioxide(SO₂)

i)Ozone(o₃)

j)Cadmium

k)Mercury

l)Asbestos


Control measures of Air Pollution:

The two types of control measures of air pollution are
1.Dilution
2.Control at source.

1.Dilution:
Tall chimneys are used to dilute the air pollutants into the atmosphere.The tall chimneys may penetrate the inversion layer of the atmosphere and disperse the contaminants by reducing the ground level contamination.
However the method of dilution is a short term control measure and it is not suitable for long term control.Because the pollutants dispersed by the tall chimneys are carried and spread around the area of disposal,this may cause harmful effects to the surrounding area

2.Control at Source:
Control of contaminants at the source is better option than the method of dilution.This can be achieved by the following ways.
a. Proper use of the existing equipment.
b. Change in process.
c. Modification or Replacement of equipments.
d. Installation of controlling equipments.


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