Today, large population pressure is exerting tremendous pressure on our natural resources. Pollution has led to an increase in the average temperature of our planet and threatens existence of life on earth.
Human population size has grown enormously over the last hundred years- exerting tremendous pressure on natural resourcesContamination - pollution
The adverse effects of chemical pollutants in the environment- not limited to us- pass on to future generations by way of genetic mutations, birth defects, inherited diseases and so on.
The need of the hour is to check the degradation and depletion of our precious natural resources and pollution without halting the process of development
Addition or excessive addition of undesirable materials to the environment or removal of desirable materials in excess.
THERE ARE two main causes of air pollution:-Human activities like industrialisation, automobile emission, overpopulation, deforestation, nuclear explosions and explosives used in wars, fireworks on festivals, thermal power stations, etc.Natural phenomena such as Volcanic eruptions releasing harmful gases and ashesElectric storms and solar flares which produce harmful chemicalsForest firesNatural organic and inorganic decays releasing methane, sulphur and other harmful substancesDust stormsBiological elements like pollen, spores, cysts, bacteria and marsh gas.
Volcanic eruptions release harmful gases and ashes.Natural organic and inorganic decays release methane, hydrogen sulphide, sulphur and other harmful substances
GASEOUS AIR POLLUTANTS ARE IN GASEOUS STATE AT ORDINARY TEMPERATURE AND PRESSURE. THEY FREELY MIX WITH AIR WITHOUT SETTLING DOWN.
Vehicles fitted with catalytic converters should be run on unleaded petrol as leaded petrol would inactivate the catalyst in the converters.
Using tall chimneys in factories can reduce pollution of air at ground level. It can induce photochemical reactions in the stratosphere.
Public transports should be used.
These oxides are mainly produced by combustion of fossil fuels, smelters, industries, power plants, automobile exhausts, domestic fires etc. nitrogen oxides are also produced in atmosphere through lightening.
Tajmahal in Agra poses a threat as the industries in AGRA are polluting the air
seminar on environmental issues, air pollution and controls
Seminar on “Environmental
Issues, Air Pollution and
3rd SEM MECHANICAL
Ms. CHETNA WAHANE
Mr. PRABHAT SINGH
• WHAT IS ENVIRONMENT?
• WHAT IS POLLUTION?
• BASIC CAUSES OF POLLUTION
• ENVIRONMENTAL MONITORING
• TYPES OF POLLUTION
• AIR POLLUTION
• CAUSES OF AIR POLLUTION
• AIR POLLUTANTS
• AIR POLLUTION CONTROLS
• ENVIRONMENTAL ISSUES
• Large human population is exerting
tremendous pressure on our natural
• With increase in human population and
great advancement in technology in the
recent past, the waste materials have
multiplied in amount as well as in kind,
and this has resulted in contamination
• Today, almost every aspect of modern
living possess potential health risks.
• Natural Resources like air, water, land,
etc. are getting contaminated with
toxic substances or chemical additives.
• It is possible that ultimately man may
become a victim of self-created
• These global environmental changes
are influencing not only air, water and
land resources but also biological
diversity and human health.
WHAT IS ENVIRONMENT?
• Environment is the physical, chemical,
biological, cultural and aesthetic surrounding
of living organisms, which contributes to the
quality of their lives.
• Our environment is a complex and dynamic
system, in which all forms of life are inter-
dependent and inter-connected.
WHAT IS POLLUTION?
• Pollution is any undesirable
change in physical, chemical or
biological characteristics of
environment which makes it
harmful for humans, living
organisms and cultural assets.
• Agents that bring about such an
undesirable change are called as
ENVIRONMENTAL MONITORING: PROCEDURE
FOR THE CONTROL OF POLLUTION
The control of pollution requires environmental
monitoring. This, in turn, needs
• Careful study of environmental characteristics,
• Laying down environmental quality standards,
• Periodic assessment of environmental
• Noting the changes in the environment and
finding out their likely effect,
• Warning people in time of likelihood of
• Planning strategies to tackle pollution such as
educating people about pollution hazards,
enacting environmental laws, legal action
against offenders, etc.
POLLUTION IS OF FOLLOWING
1. Atmospheric or air pollution,
2. Hydrospheric or water
3. Lithospheric or land or soil
4. Radioactive pollution, and
5. Noise or sound pollution.
• An undesirable change in the
physical, chemical, or biological
aspects of air which makes it
harmful for humans, for other
living organisms and for cultural
assets is called air pollution.
a. HUMAN ACTIVITIES
• Automobile emissions
• Nuclear explosion and explosives used in
• Thermal power stations, etc.
b. NATURAL PHENOMENA
• Volcanic eruptions
• Electric storms and solar flares which
produce harmful chemicals
• Forest fires
• Natural organic and inorganic decays
• Dust storms
• Biological elements like pollen, spores, cysts,
bacteria and marsh gas.
Three types of steps
can be taken to
control air pollution:-
• Separation of pollutants
from harmless gases,
• Avoidance of pollutants
• Conversion of pollutants
to harmless materials.
SEPARATION OF POLLUTANTS
Growing trees: certain plants (Phaseolus
vulgaris, Coleus blumeri, Ficus variegata) can
fix CO and some plants (Pinus, Junipers,
Quercus, Pyrus, Vitis) can metabolise
nitrogen oxides. Plantation of such species
should be encouraged along with other
Use of sulphur and lead free good quality
Control of Particulate Matter:- we can use
devices termed arrestors in the industries and
catalytic converters in the automobiles.
• Arresters :- Control equipments such as gravity
settling tanks or porous filters, electrostatic
precipitators, cyclonic separators and
trajectory separators can minimise air
• Catalytic converters:- This device has metals
like platinum, palladium and rhodium as
catalysts. As the exhaust passes through it,
unburnt hydrocarbons are converted into CO₂
and water, and CO and nitric oxide are changed
to CO₂ and N₂ respectively.
Control of Gaseous Pollutants:-
1. Combustion method:- In this method,
oxidisable pollutants particularly in
petrochemical, fertilisers, paints and varnish
industries are burnt at high temperature.
2. Absorption method:- This method employs
dry or wet scrubbers having packing material
where gaseous pollutants are absorbed.
For instance, calcium hydroxide or a bed of lime
is used to absorb sulphur dioxide. A fine spray of
water dissolves nitrogen oxides, sulphur oxides
3. Adsorption technique:- This method is
employed to remove toxic gases, vapour and
inflammable compounds from the polluted air
by using very fine solid particles (e.g., activated
charcoal). The electrostatic precipitators
remove smaller particles.
Using tall chimneys in factories reduce pollution
of air at ground level.
Industrial smoke should be filtered before
releasing into the air to remove particulate
Poisonous gases should be removed by
passing the fumes through water tower
scrubber or spray collector.
Mining area should be afforested.
AVOIDANCE OF POLLUTANTS
• Use of automobiles should be minimised.
• Conventional fuels (firewood, coal, oil)
should be replaced by electricity or natural
gas. These fuels do not emit SO₃.
• Population should be brought under control.
• Nuclear explosions and wars should be
• Non-conventional fuel should be used which
are pollution free.
• Pollution free fuels (alcohol, hydrogen,
battery power) should be developed for
• Complete electrification of rail track will
greatly reduce air pollutants.
• It means conversion of
pollutants into harmless
• This may be done by oxidation in
air or by chemical neutralisation
of acids and bases.
• Acidification of environment is a man-made
• Acid rain refers to precipitation with a pH of
less than 5.
• It is a mixture of H₂SO₄ and HNO₃; the ratio of
the two acids vary depending on the relative
quantities of sulphur oxides and nitrogen
oxides present in the atmosphere.
• In the atmosphere, SO₂ and Noₓare
changed into sulphuric acid (H₂SO₄) and
nitric acid (HNO₃) respectively by
combining with oxygen and water.
2SO₂ + O₂ → 2SO₃
SO₃ + H₂O → H₂SO₄
2NO + [O]→ N₂O₅
N₂O₅ + H₂O → 2HNO₃
EFFECTS OF ACID RAIN
• Results in acidification of water bodies
• pH less than 5 kills plankton, molluscs and most
fishes in water bodiesFAUNA
• Corrodes metals, marbles, painted
surfaces, slate, stone, etc.
• Causes stone leprosy.
Green House Effect and Global
• The greenhouse effect is a naturally occurring
phenomenon that is responsible for heating of
earth’s surface and atmosphere.
• Only half of incoming solar radiations fall on
Earth’s surface heating it.
• Earth’s surface re-emits heat in the form of
infra-red radiation but part of it doesn’t
escape into space as atmospheric gases (e.g.,
CO₂, CH₄, etc.) absorb a major fraction of it.
• The molecules of these gases radiate heat
energy, and a major part of which again comes
to earth’s surface, thus heating it up once again.
The cycle repeats many times.
• The above mentioned gases are called
greenhouse gases because they are responsible
for the greenhouse effect.
• Increase in the level of greenhouse gases has led
to considerable heating of earth leading to
Melting of polar and Himalayan
Global environmental changes
(e.g., El Nino Effect) and rise in
the earth’s average temperature
The total spectrum of changes
that global warming can bring is
still under active research
• Cutting down use of
• Increasing energy
• PLANTING TREES
• Slowing down the
population growth rate
• International initiatives like
setting up norms for the
countries of the world, etc.
• Ozone layer in the upper part of the atmosphere
acts as a shield absorbing UV radiation from the
• Ozone is continuously formed by the action of UV
rays on molecular oxygen, and also get degraded
into molecular oxygen in the stratosphere.
• This balance between production and
degradation of ozone in the stratosphere has
been disrupted due to enhancement of ozone
degradation by chlorofluorocarbons (CFCs).
• In stratosphere, UV rays act on CFCs releasing Cl
• Cl degrades ozone releasing molecular oxygen, with
these atoms acting merely as catalysts; Cl atoms are
not consumed in the reaction. Thus, a single Cl
atom can degrade large amount of ozone.
• Although ozone depletion is occurring widely in the
stratosphere, the depletion is particularly marked
over the Antarctic region.
• This has resulted in formation of a large area of
thinned ozone layer, commonly called as the ozone
• Agreement signed by 27 countries to limit the use of Ozone Depleting
• Agreement to help developing countries implement the alternatives to CFCs.
• United Nations Conference on Environment and Development (commonly
called EARTH SUMMIT)was held in Rio de Janero in 1992.
• Recommendations of Conference on Climate Change were signed by 154
nations to limit the emissions of greenhouse gases at 1990 level.
• An agreement was signed by different countries in 1997 to mitigate global
environmental change by taking appropriate measure to reduce emissions of
greenhouse gases at a level 5% below the 1990 level by 2012.
• Today, our environment is facing anthropological
• Burning issues of global environmental change like
global warming and ozone depletion are
threatening the existence of living world.
• The need of the hour is to stabilise the
atmospheric concentrations of green house gases
which is possible only when all the countries join
hands in lowering the global emission of green
house gases from their present levels.