Air Pollution
&
Control
Dr. Krishnendu Kr. Pobi
Dept. of BS & HU (Chemistry),
Asansol Engineering College, West Bengal
Mail ID: krishnendupobi@gmail.com
Contact: +91-9475017775
Vivekananda Sarani, Asansol,
West Bengal-713305
Structure of the Atmosphere
Learning about different states of the atmosphere enables
science to understand and predict changes on a range of
scales.
Meteorology is the subject that studies the chemical and
physical properties of the atmosphere together with its fields
of motion, mass and moisture.
How was is formed?
At the time of the Earth's formation around 4.5 billion years ago there was probably no
atmosphere. It is believed to have come into existence as a result of the volcanic expulsion of
substances from its interior, mainly water vapour, with some carbon dioxide, nitrogen and sulphur.
The atmosphere can only hold a certain amount of water vapour, so the excess condensed into
liquid water to form the oceans.
It is thought that the first stage in the evolution of life on Earth required an oxygen-free
environment. Later primitive forms of plant life developed in the oceans and began to release small
amounts of oxygen into the atmosphere as a waste product from the cycle of photosynthesis:
H2O + CO2 + sunlight → sugar + O2
This build-up of atmospheric oxygen eventually led to the formation of the ozone layer.
This layer, approximately 8 to 30 km above the surface, helps to filter the ultraviolet portion of the
incoming solar radiation. Therefore, as levels of harmful ultraviolet radiation decreased, so plants
were able to move to progressively higher levels in the oceans.
This helped to boost photosynthesis and thereby the production of oxygen. Today, this
element has reached levels where life has been sustainable on the surface of the planet through its
presence, and it should be remembered that oxygen is an element which is not commonly found in
the universe.
Atmospheric Composition
Main Elements = 99%
Nitrogen (N2) =78%
Oxygen (O2) =21%
Trace Elements = 1%
Xenon (Xe), Argon (Ar),
Ozone (O3), Carbon Dioxide (CO2),
Nitrogen Dioxide (NO2), Neon (Ne),
Iodine (I), Helium (He),
Carbon Monoxide (CO), Methane (CH4),
Ammonia (NH3), Nitrous Oxide (N2O),
Water Vapour (H20)
Vertical structure of the atmosphere
The atmosphere is divided into four
isothermal
layers
or
'spheres':
troposphere, stratosphere, mesosphere
and thermosphere.
Each layer is characterized by a
uniform change in temperature with
increasing altitude.
In some layers there is an increase in
temperature with altitude, whilst in
others it decreases with increasing
altitude.
The top or boundary of each layer is
denoted by a 'pause„ where the
temperature profile abruptly changes.
Troposphere
The troposphere contains about 80% of the atmosphere and is the part of the
atmosphere in which we live, and make weather observations.
In this layer, average temperatures decrease with height 6.4ºc/1000m, as there is
less air in contact with the ground to heat up. This is known as Environmental Lapse rate
(adiabatic cooling brought about by changes in temperature caused by a decrease in
pressure at height).
This sphere mixes vertically by convection, conduction and turbulence more than
any other sphere. These vertical motions and the abundance of water vapour make it the
home of all important weather phenomena.
The troposphere is around 16 km high at the equator, with the temperature at the
tropopause around –80 °C. At the poles, the troposphere reaches a height of around 8 km,
with the temperature of the tropopause around –40 °C in summer and –60 °C in winter.
Therefore, despite the higher surface temperatures, the tropical tropopause is much cooler
than at the poles at the thickness is increased – more cooling occurs.
Stratosphere
Temperatures in the stratosphere rise with increasing altitude (creating a
temperature inversion) this is caused by concentrations on O3 which absorbs
ultraviolet radiation. This is greatest around 50 km at the edge of the
stratopause. Temperatures range from – 30 °C over the winter pole to +20 °C
over the summer pole according to latitude and season.
As well as a noticeable change in temperature, the move from the troposphere
into the stratosphere is also marked by an abrupt change in the concentrations
of the variable trace elements. Water vapour decreases sharply, whilst ozone
concentrations increase. These strong contrasts in concentrations are a
reflection of little mixing between the moist, ozone-poor troposphere and the
dry, ozone-rich stratosphere.
The stratosphere extends up to around 48 km above the surface, and together
with the troposphere, they account for 99.9% of the Earth's atmosphere.
Mesosphere
Temperatures in the mesosphere decrease rapidly as there is no water vapour,
cloud, dust or ozone to absorb incoming radiation.
Temperatures at the mesopause go as low as –120 °C with very strong winds –
3000km/hr.
As in the troposphere, the unstable profile means that vertical motions are not
inhibited. During the summer, there is enough lifting to produce clouds in the
upper mesosphere at high latitudes
Thermosphere
The thermosphere extends upwards to altitudes of several hundred kilometres,
where temperatures range from 250oc to as high as 1,700oc, getting warmer
with increasing height.
Temperature ranges depend on the degree of solar activity and as there is more
atomic oxygen there (like ozone) to absorb the heat.
The temperature changes between day and night (Diurnal) amount to hundreds
of degrees.
Above 500 km temperatures are very difficult to define. Molecules are so
widely spaced that they move independently, and there is no reason why their
temperatures should be the same.
Chemical composition in different atmospheric region
Air Pollution
&
Control
Dr. Krishnendu Kr. Pobi
Dept. of BS & HU (Chemistry),
Asansol Engineering College, West Bengal
Mail ID: krishnendupobi@gmail.com
Contact: +91-9475017775
Vivekananda Sarani, Asansol,
West Bengal-713305
What is air Pollution?
Air is essential life supporting resources, without it we could
survive only a few minutes. It constitutes immediate physical environment
of living organisms.
Air pollution is basically the presence of foreign substances in air in
excessive concentration which adversely affect the well being of the
individual or causes damage to property.
According to World Health Organization, air pollution is defined as
“Substances put into air by activity of mankind into concentration
sufficient to cause harmful effect to his health, vegetables, property, or
interfere with the enjoyment of his property.”
AIR POLLUTANTS
 Particles:- Dust, Smoke,
Fly ash
 Carbon monoxide
 Carbon dioxide
 Ammonia
 Sulphur dioxide
 Nitrogen oxide
 Hydrogen cyanide
 Hydrogen sulphide
 Hydrogen floride
 Chlorine
 Phosgene
 Asbestors
 Aldehydes
 Radiations
 Hydocarbons
CLASSIFICATION
 PRIMARY AIR POLLUTION
The poisonous gases and
undesirable chemical which cause air
pollution. They are emitted directly
to the atmosphere.
 Carbon monoxide (CO)
 Sulphur dioxide (SO2)
 Nitrogen dioxide (NO2)
 Hydocarbons (HCs)
 Radio active compounds
 Particles of metals
 Pollens
 Bacteria, etc.
 SECONDARY AIR POLLUTION
Those which are produced in
the air by the interaction among two
or more primary air pollution.
 Ozone (O3)
 Peroxyacetyl nitrrate (PAN)
 Formaldehyte
 Formation of acid rain
 Photochemical Smog
SOURCES OF AIR POLLUTION
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NATURAL
Natural Contaminants (fungi,
spores, cysts, bacteria, methane,
dust, etc.)
Carbon monoxide from methane
gas
Volcanic Eruptions
Forest fire
Electric storms & solar flares
Salt spray from ocean
Dust storms
Hydrogen sulphite
Cosmic dust
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MAN-MADE SOURCE
Emission from vehicle
Rapid industrialization
Agricultural activities
War fares
Automobile revolution
Deforestation, etc.
Burning of fossils fuel
EFFECTS OF AIR POLLUTION
ON HUMAN HEALTH
 Eye irritation can be caused by mainly air pollutant such as NOX, O3,
PAN, pesticides, etc.
 Increase in mortality and morbidity rate
 Heavy metals, like lead may enters through lung cause poisoning
 Dust particles can cause specific respiratory disease like silicosis,
asbestosis, etc.
 Cadmium particles cause cardiovascular disease, kidney and liver
damage.
 Nickel particles causes respiratory damage
 Radioactive substances affect future generation.
ON ANIMAL
 Fluorine:- almost all farm animals, cattle, and sheep are susceptible to
fluorine toxicity. Horses are quite resistant. Fluorine is a cumulative
poison under conditions of continuous exposure to sub acute doses. Its
effect include lack of appetite, rapid loss of weight, periodic diarrhea,
etc.
 Lead:- Chronic lead poisoning have been observed frequently in
animals that have been grazing smelter and lead mines.it cause
paralysis, and difficult in breathing.
 Arsenic:- Acute case causes severe salivation, thirst, loss of appetite,
paralysis and Diarrhea. In Chronic arsenic poisoning cause cough,
Diarrhea, Anemia, paralysis and death.
Air Pollution
&
Control
Dr. Krishnendu Kr. Pobi
Dept. of BS & HU (Chemistry),
Asansol Engineering College, West Bengal
Mail ID: krishnendupobi@gmail.com
Contact: +91-9475017775
Vivekananda Sarani, Asansol,
West Bengal-713305
Carbon monoxide (CO)
 It is a colourless, odourless gas that is poisonous animals. It is formed
by incomplete combustion of carbon containing fuels.
 Source of carbon monoxide is cigarette smoking and incomplete
combustion of fossil fuels (more than 77% comes from motor vehicle
exhaust).
Health effects include reduced ability of red blood cells to carry oxygen
to body cells and tissues. This leads to headache and anemia. At high
levels it causes coma, irreversible brain damage and death.
Nitrogen Dioxide(NO2)
 It is a reddish-brown irritating gas that causes photochemical smog. In
the atmosphere, it gets converted into nitric acid (HNO3). It is caused
by burning fossil fuels in industries and power plants.
 Health effects include lung irritation and damage. Environmental
effects involve acid deposition leading to damage of trees, lakes, soil
and ancient monuments. NO2 can damage fabrics.
Sulphur Dioxide(SO2)
 It is a colourless and irritating gas that is formed by combustion of
sulphur containing fossil fuels such as coal and oil. In the atmosphere it
is converted into Sulphuric acid which is a major component of acid
deposition.
 Health effects involve breathing problems for healthy people.
 Environmental effects involve reduced visibility and acid deposition
on trees, lakes, soils and monuments leading to their deterioration and
adverse effect on aquatic life.
Suspended Particulate Matter (SPM)
 Includes a variety of particles and droplets (aerosols) that can be
suspended in atmosphere for short to long periods.
 Human sources for SPM include burning coal in power and industrial
units, burning diesel and other fuels in vehicles, agriculture, unpaved
roads, construction, etc.
 Health effects include nose and throat irritation, lung damage,
bronchitis, asthama, reproductive problems and cancer.
 Environmental Effects include reduced visibility and acid deposition.
Acid deposition may lead to damaged trees, soils and aquatic life in
lakes.
Lead (Pb)
 It is also known as plumbum (Pb). It is bluish grey metal (mp 327ºC)
and very soft in nature.
 It is mainly derived in the natural environment from automobile
emission, burning of oil and gas, mining & plumbing, metal smelters
and manufacturing lead-acid batteries etc.
 Health effects include liver and kidney damage, mental retardation in
children, and abnormalities in fertility and pregnancy.
Ground Level Ozone (O3)
 It is a highly reactive gas with an unpleasant odour occurring in the
stratosphere where it protects mankind from the harmful ultra-violet
rays from the Sun. However on earth, it is a pollutant.
 In the troposphere, O3 is a secondary pollutant, and it occurs on earth
due to reaction between Volatile Organic Compounds (VOCs) and
Nitrogen Oxides.
NO2+hv→NO+O (λ <390nm)
O+O2+N2→O3+N2
Without third body, the so formed O3 would not have been stable and
would have reverted back to O and O2. When we inhale air containing O3,
it poses threat.
References
1.
2.
Gourkrishna Dusmohapatra, 2014, Basic Environmental Engineering and
Elementary Biology, Vikas publishing house Pvt. Ltd.
Patra & Singha, “Basic Environmental Engineering & Elementary
Biology”, Aryan publishing house.
Assignments
1.
2.
3.
4.
What is air pollution?
Classify air pollutants .
What do you mean by criteria pollutants ?
Describe the sources, biochemical effects and sinks of carbon
monoxide.
Thank You