Air Pollution PDF Notes

 Air Pollution


• Air Pollution is a mixture of solid particles and gases in
the air. Car emission chemical from factories, dust, pollen and mold spores may
be suspended as particles.

• Ozone a gas is a major part of air Pollution in cities.

• When Ozone forms air Pollution it’s also called smog.

Type of Air

The most common and harmful Pollutant outdoors include:-

1.   Particulate

2.   Nitrogen dioxide

3.   Ozone

4.   Sulphur dioxide

Particulate matter is a mix of solid and liquids including carbon
complex organic chemicals, sulphates, Nitrates, Mineral dust, and water
suspended in the air.

(2)Nitrogen dioxide:-
Nitrogen dioxide is a gas and is a major component of urban air Pollution

(3) Ozone:- Ozone
is a gas composed of 3atoms of Oxygen. It the upper level of the earth’s
atmosphere. It absorbs harmful ultraviolet radiation.

(4) Sulphur dioxide:-
So2 is a colorless gas with a pungent, suffocating smell. It’s produced by

Sulphur containing fuels such as Coal and Oil. This includes
vehicles, power generation and heating.

Caused of Air

• It caused by solid and liquid particles and certain gases
that are suspended in the air. These Particles and gases can come from car,
truck exhaust, factors, dust and wildfire.

• It solid and liquid particles suspended in our air are
called Aerosol.

Effect of Air
Pollution on environmental:-

Air Pollution can damage crops and trees in a variety of
ways. Ground level Ozone can lead to reductions in agricultural crops and
commercial forest yields reduced growth and survivability of tree seedlings and
increase plant susceptibility to decrease pests and other Environmental

Monitoring and
control of Air Pollution:-

Monitoring is an exercise to measure ambient air Pollution
levels in an area. The date will indicate the status of the quality of air we

The date over a long term allows us to tease out patterns
that help support air Pollution control.

Control measures
  Some effective
techniques to control air Pollution are as follow:-

A) Source Correction Methods

B) Pollution Control Equipment

C) Diffusion of Pollutant in air

D) Vegetation

E) Zoning

A) Source Correction
Industries make a major contribution towards causing Air
Pollution. Formation of Pollutants can be prevented and their emission can be
minimised at the source itself.

This source correction method are.

1) Substitution of
row materials:-
If the use of a particular row material result in air
Pollution then It should be substituted by another purer grade row material
which reduces the formation of Pollutants.

• Low Sulphur fuel which has less Pollution potential can be
used as an alternative to high Sulphur fuels.

• Comparatively more refined LPG or LNG (Liquefied Natural
Gas) can be used instead of traditional high contamination fuels such as Coal.

2) Process
It coal is washed before Puluerization then fly-ash
emissions are considerably reduced.

If air intake of boiler furnace is adjusted then excess
Fly-ash Emission at power Plant can be reduced.

B) Pollution Control
Sometimes Pollution control at source is not possible by
preventing the emission of Pollutants. Then it becomes necessary to install
Pollution control equipment to remove the gaseous Pollutants from the main gas

They are classified into two types

•Control devices for particulate contamination.

• Control devices for gaseous contaminates

C) Diffusion of
Pollutants in Air:-

Dilution of the Contaminate in the atmosphere is another
approach to the control of air Pollution.

The Pollution source release only a small quantity of the
Contaminates then Pollution is not noticeable as these pollutants easily
diffuse into the Atmosphere but if the quality of air contamination is beyond
the limited capacity of the environment to absord the contaminats then
Pollution is caused.

However dilution of the contaminats in the atmosphere can be
accomplished through the use of tall stacks which penetrate the upper
atmosphere layers and disperse the contaminats so that the ground level
Pollution is greatly reduced the hight of the stacks is usually kept 2 to 2½
time the height of nearby structures.

The disadvantage of the method is that it is a short term
contract solution that actually brings highly undesirable long range effect.

This is so because dilution only dilutes the contaminats to
level at which their harmful effects are less noticeable near their original
source whereas at a considerable distance from the source these very
contaminats eventually come down in some form or another.

D) Vegetation:-
Plants contribute towards controlling Air Pollution by utilising CO2 and O in
the process of photosynthesis.

This purifies the air (removal of gaseous pollutant – Co2)
for the respiration of men and animals.

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