This slide show consists of slides related to air pollution .It consists of sources of air pollution, atmospheric stability , classification of air pollutants and other information.

1. AIR POLLUTION

2. INTRODUCTION
• Nature is our mother. She offers us all facilities to
lead a comfortable and peaceful life. She brings us
rain. She feeds the human beings who are her
children. The plants, trees, bushes and the grains we
grow all belong to nature. Yet man is not grateful to
nature. He pollutes the surroundings and brings
destruction on himself. Man’s ability to manipulate
the environment has today resulted in Several Serious
problems. The most Serious of these problems, is the
environmental pollution

3. • Environmental pollution can be defined as an
undesirable change in the physical, chemical and
biological characteristics of the environment such
changes are caused by Substances that are introduced
into the environment, by human activities.
• Air pollution
• Water pollution
• Noise Pollution
• Soil pollution
• Marine pollution
• Thermal Pollution
• Solid waste pollution

4. Air pollution - It may be defined as any atmospheric condition in
which certain substances are present in such concentration that
they can produce undesirable effect on man and his environment.
These substances includes gases (CO2,SO2,NO2,CO,HF,HC etc.),
particulate matters ( smoke, dust, fumes, aerosols etc.) ,
radioactive materials and many others.

5. Composition of clean and dry atmospheric air
Sr. No. Component Concentration (ppm)
1 Nitrogen 78x10 4
2 Oxygen 21x10 4
3 Argon 0.93 x10 4
4 Carbon dioxide 0.032x10 4
5 Caron monoxide 0.1
6 Methane 1.2
7 Nitrous Oxide 0.25
8 Nitric Oxide 0.0006
9 Hydrogen Sulphide 0.0002
10 Sulfur dioxide 0.0002
11 Ozone 0.04

6. The concentration of pollutants in the
atmosphere is expressed as:
• Mass concentration: It is the ratio of mass of pollutants to
the mass of air plus mass of pollutants.
• Volume concentration: It is the ratio of Volume of
pollutants to the Volume of air plus volume of pollutants.
• Mass volume concentration : It is the ratio of mass of
pollutants to the volume of air plus volume of pollutants.
• Most of the time concentration of pollutants is
expressed in ppm or microgram per cubic meter
(µg/m3
).

7. Conversion of pollutants Concentration
Conc. in µg/m3
=
ppm conc. x molecular wt. of pollutant x 103
_____________________________________
22.41
at 0o
c and 760 mm of Hg pressure
ppm conc. x molecular wt. of pollutant x 103
_____________________________________
24.51
at 25o
c and 760 mm of Hg pressure
Conc. in µg/m3
=

8. Sources of Air Pollution
Natural – i)Volcanic eruption- poisonous gases- SO2,CO ,H2S etc.
ii) Forest fires-smoke, dust,CO2 and un-burnt hydrocarbons etc.
iii) Natural organic and inorganic decay
iv) Deflation of sand and dust
v) Pollen grains of flowers, weeds , grasses and trees.
vi) Evapotranspiration- CO2
Manmade- i) Rapid Industrialization- CO2,SO2,CO ,NO, H2S etc.
ii)Transportation- NO2,CO,Hydrocarbons,Nitrous oxide
iii) Burning of fossil fuels- CO2, SO2,CO,NO, CH4
iv) deforestation- balance between O2 and CO2 disturbed
v) Increase in population
vi) Agriculture activities
vii) Solid waste disposal
viii) Radioactive fall out
ix) Construction activities
x) Wars

9. Sources of air pollutants
• Stationary sources:
Point sources - industrial stacks
Area sources - open burning, Evaporation losses
• Mobile sources:
Line sources - vehicle, rail engine
Area sources - vehicles on Road

10. Classification of Air pollutants
1. According to Origin-
PRIMARY – emitted directly from source
e.g. i) Particulate matter- ash, smoke, dust, fumes, mist etc.
Mist- liquid droplets smaller than 10µ size formed by
condensation or released from industrial operations.
Fumes – these are solid particles generated by condensation from
gaseous state.
ii) Inorganic gases- SOx, NOx,CO,CO2,HF etc.
SECONDARY – formed by chemical or photochemical
reactions between two or more primary pollutants.
e.g. O3, PAN(peroxy acetyl nitrate), formaldehyde, photochemical
smog etc.

11. 2. According to Chemical Composition-
i)ORGANIC- e.g. Hydrocarbons, esters, aldehydes etc.
ii)INORGANIC- e.g. Sox, Nox, CO,CO2,HF,O3,HCl etc.
3. According to State of Matter
i) NATURAL CONTAMINANTS – e.g. Fog, pollen grains,
bacteria etc.
ii) PARTICULATE MATTER- e.g. Ash, smoke, dust, spray
fumes, mist etc.

12. Meteorology and Air Pollution
• The degree to which air pollutants discharged from various
sources concentrate in a particular area depends largely on
meteorological condition.
The important meteorological parameters that influence air pollution
are classified into primary and secondary parameters.
Primary parameters: i) Wind direction and wind speed
ii) Atmospheric stability
iii) Temperature
iv) Mixing height
Secondary parameters: i) Precipitation
ii) Humidity
iii) Solar radiations
iv) Visibility

13. • Atmospheric stability: In well mixed air which is dry, for every
300m increase in altitude, the temperature decrease by 1.8 oc
.This vertical temperature gradient is know as lapse rate.
• The tendency of atmosphere to resist vertical motion is called as
stability. This stability depends on wind speed and lapse rate.
• The change of air temperature with altitude has a profound
influence on the vertical lift of the air pollutants discharged into
the atmosphere and hence their dispersion and dilution.
• Inversion: The extreme case of stable environment, called an
inversion, occurs when temperature increases with altitude.
Such lapse rate is known as negative lapse rate. Under these
conditions, the atmosphere is very stable and practically no
mixing of pollutants takes place.

14. Types of Inversion
• Radiation Inversion: It occurs at nights,
when the earth loose heat by radiation and
cools the air in contacts with it. The cool air
stratum is covered by warmer air, and
vertical movement is stopped until the sun
worms the lower air, next morning. This
type of inversion is more common in
winter because of longer nights.
• Subsidence Inversion: It occurs at modest
altitude and remain for several days. It
occurs due to sinking or subsiding of air
mass in anticyclones. The air circulating
around the area descends slowly at the rate
of about 1000m per day. As the air sinks ,it
is compressed and get heated to form a
warm dense layer. This acts as a lid to
prevent the upward movement of
contaminants( pollutants).

15. • Advective Inversion: It is formed when
warm air moves over a cold air. The
inversion can be ground based in the former
case or elevated in later case. An example
of advective inversion occurs when hill
range forces a warm land breeze to flow at
high levels and a cool sea breeze flows at
low level in opposite direction.

16. Atmospheric stability conditions

17. Plume Behaviour
a)Looping: Occurs under super adiabatic condition
with light to moderate wind on hot summer.
b) Neutral: When ambient lapse rate and adiabatic lapse
rate are equal, plume coming out of chimney tends to
rise directly into the atmosphere until it reaches the air
of density similar to that of plume itself.
c)Coning: while it tends to cone ,when wind velocity
is more than 32 km/hr & cloudy skies both during
day and night.
d)Fanning: when lapse rate is –ve, plume get depressed
in presence of very light wind ,as a result of strong
atmospheric inversion.
e)Lofting: It occurs when lapse rate is super adiabatic
above emission source and inversion condition below
the emission source. No downward mixing.
f)Fumigation: It occurs when inversion above emission
source and super adiabatic lapse rate below the stack.
g)Trapping: It occurs when inversion condition are
developed ,both above and below the emission source.

18. Effects of Air pollution
On human health: Exposure to air pollution can cause both acute (short-term) and
chronic (long-term) health effects.
Acute effects are usually immediate and often reversible when exposure to the
pollutant ends. Some acute health effects include eye irritation, headaches, and
nausea.
Chronic effects are usually not immediate and tend not to be reversible when
exposure to the pollutant ends. Some chronic health effects include decreased lung
capacity and lung cancer resulting from long-term exposure to toxic air pollutants.
1. Particulate matter of size 1micron enter into the alveoli of lung and damage lung
tissues.
2. Asbestos fibers may cause cancer to the industrial workers.
3. Lead from automobile exhaust may effect on children’s brain. It also interferes
with the development and maturation of red blood cells.
4. Silicosis a chronic of lung is caused by inhalation of dust containing free silica.
5. Black Lung disease is common among coal miners, while white Lung disease
occurs in texture workers.
6.Acid particulate and aldehydes cause eye, noise and throat irritation.

19. 7. High conc. of CO can cause physiological and pathological changes and
ultimately death. If Conc. of CO increases above 750 ppm, it will cause death.
8.. The combination of CO and haemoglobin leads to the formation of
caroxhaemoglobin ( COHb). The COHb reduces the oxygen carrying of blood.
9. When conc. of CO is more than 100 ppm, most of the people experience
dizziness ,headache and lassitude.
10. Cigarette smoke contains 400 – 450 ppm of CO. hence % age of
caroxhaemoglobin ( COHb) increase in blood of cigarette smokers. Smoking
leads to fertility problem, premature births, spontaneous abortions and deformed
babies.
11. SO2 and SO3 conc. of about 2.5 ppm may cause intense irritation of eyes and
respiratory tract.
12. SO2 inhalation causes the symptoms of bronchitis and other hung disease. If
SO2 concentration increases in air it may leads to lung cancer.
13.Nitric oxide reduces the oxygen carrying capacity of blood.
14. High conc of Nox cause internal bleeding, Pneumonia, lung cancer and
oxygen deficiency. It also causes respiratory, nervous and digestive aliment.
15 Hydro carbons of various types are harmful to health. They may leads to
cancer, irritation of eyes ,nose, throat and respiratory distress.

20. Effect on plant or vegetation
1. The deposition of particulate pollutants containing toxic metal ,make soil
unsuitable for growth of plants.
2. Particulate pollutants after deposition on plant leaves, block the stomata
opening on the leave, thus reduces its growth.
3. Particulate fallout with acid rain, reduces the pH of soil which makes soil
infertile
4. Low conc of SO2 for long period may results in brownish red or bleach
area on leaf.
5. SO2 damage the vegetable crops and affect their growth.
6. At high conc of SO2 ,leaf tissue may die leading to leaf necrosis.
7. High conc of NO2 damage the leaves of the plants and retard the
photosynthetic activity.
8. HC may cause death of flowering plants.
9. Arsenic and ethylene inhibits the growth of plants.
10. Hydrocarbons and photochemical oxidant are injurious to plants ,leading
to chlorosis.

21. Effect on Materials
1.Particulate matter such as soot's, fumes, mist may cause severe damage to
buildings and monument's.
2. Corrosion activity may enhances in presence of particulate matter and
humidity.
3. Particulate matter may cracks and fading in pointed surfaces.
4.Nitric acid causes corrosion to metal surfaces.
5. NO2 may fades textile dyes, NO2 aerosol may damage the nylon fibres
and reduce the strength of cotton and rayon.
6. Ozone in conc. between 0.01 to 0.03 ppm may cause cracking of synthetic
rubber and fibres .
7. Cracking of rubber tyres and other rubbery parts takes due to different air
pollutants.

22. Table 1: Sources, Health and Welfare Effects for Criteria Pollutants.
Pollutant Description Sources Health Effects Welfare Effects
Carbon
Monoxide
(CO)
Colorless, odorless
gas
Motor vehicle exhaust,
indoor sources include
kerosene or wood burning
stoves.
Headaches, reduced mental
alertness, heart attack,
cardiovascular diseases,
impaired fetal development,
death.
Contribute to the formation of
smog.
Sulfur Dioxide
(SO2
)
Colorless gas that
dissolves in water
vapor to form acid,
and interact with other
gases and particles in
the air.
Coal-fired power plants,
petroleum refineries,
manufacture of sulfuric acid
and smelting of ores
containing sulfur.
Eye irritation, wheezing, chest
tightness, shortness of
breath, lung damage.
Contribute to the formation of
acid rain, visibility impairment,
plant and water damage,
aesthetic damage.
Nitrogen
Dioxide (NO2
)
Reddish brown, highly
reactive gas.
Motor vehicles, electric
utilities, and other
industrial, commercial, and
residential sources that
burn fuels.
Susceptibility to respiratory
infections, irritation of the lung
and respiratory symptoms
(e.g., cough, chest pain,
difficulty breathing).
Contribute to the formation of
smog, acid rain, water quality
deterioration, global warming,
and visibility impairment.
Ozone (O3
) Gaseous pollutant
when it is formed in
the troposphere.
Vehicle exhaust and certain
other fumes. Formed from
other air pollutants in the
presence of sunlight.
Eye and throat irritation,
coughing, respiratory tract
problems, asthma, lung
damage.
Plant and ecosystem damage.
Lead (Pb) Metallic element Metal refineries, lead
smelters, battery
manufacturers, iron and
steel producers.
Anemia, high blood pressure,
brain and kidney damage,
neurological disorders,
cancer, lowered IQ.
Affects animals and plants,
affects aquatic ecosystems.
Particulate
Matter (PM)
Very small particles of
soot, dust, or other
matter, including tiny
droplets of liquids.
Diesel engines, power
plants, industries,
windblown dust, wood
stoves.
Eye irritation, asthma,
bronchitis, lung damage,
cancer, heavy metal
poisoning, cardiovascular
effects.
Visibility impairment,
atmospheric deposition,
aesthetic damage.

23. Pollutants Sources Effects on Vegetables
Aldehydes Photochemical reactions The upper portions of Alfalfa etc. will be affected to Narcosis
if 250 ppm of aldehydes is present for 2 hrs duration.
Ozone (O3
) Photochemical reaction of hydrocarbon
and nitrogen oxides from fuel
combustion, refuse burning, and
evaporation from petroleum products.
All ages of tobacco leaves, beans, grapes, pine, pumpkins
and potato are affected. Fleck, stipple, bleaching, bleached
spotting, pigmentation, growth suppression, and early
abscission are the effects.
Peroxy Acetyl
Nitrate (PAN)
The sources of PAN are the same as
ozone
Young spongy cells of plants are affected if 0.01 ppm of PAN
is present in the ambient air for more than 6 hrs.
Nitrogen dioxide
(NO2)
High temperature combustion of coal, oil,
gas, and gasoline in power plants and
internal combustion engines.
Irregular, white or brown collapsed lesion on intercostals
tissue and near leaf margin. Suppressed growth is observed
in many plants.
Ammonia & Sulfur
dioxide
Thermal power plants, oil and petroleum
refineries.
Bleached spots, bleached areas between veins, bleached
margins, chlorosis, growth suppression, early abscission,
and reduction in yield and tissue collapse occur.
Chlorine (Cl2) Leaks in chlorine storage tanks,
hydrochloric acid mists.
If 0.10 ppm is present for at least 2 hrs, the epidermis and
mesophyll of plants will be affected.
Hydrogen fluoride,
Silicon
tetrafluoride
Phosphate rock processing, aluminum
industry, and ceramic works and
fiberglass manufacturing.
Epidermis and mesophyll of grapes, large seed fruits, pines
and fluorosis in animals occur if 0.001 ppm of HF is present
for 5 weeks.
Pesticides &
Herbicides
Agricultural operations Defoliation, dwarfing, curling, twisting, growth reduction and
killing of plants may occur.
Particulates Cement industries, thermal power plants,
blasting, crushing and processing
industries.
Affects quality of plants, reduces vigor & hardness and
interferences with photosynthesis due to plugging leaf
stomata and blocking of light.
Mercury (Hg) Processing of mercury containing ores,
burning of coal and oil.
Greenhouse crops, and floral parts of all vegetations are
affected; abscission and growth reduction occur in most of
the plants.
Table-2: Sources, Effects of Air Pollutants on Vegetables

24. Control of air pollution
• Process change
• Fuel Change
• Installment of control Equipments
Particulate control Equipments: basic mechanisms for removing
particulate matter may be classified as: Gravitational force or
settling, centrifugal force or impaction, Inertia force or impaction,
direct interception, diffusion and electrostatic precipitation.
Gravitational settling chamber Cyclone separator
Fabric filter Electrostatic precipitator
Wet scrubbers etc.

25. Gravitational settling Chamber
• Settling chambers use the force of gravity to remove solid
particles.
• The gas stream enters a chamber where the velocity of the gas is
reduced. Large particles drop out of the gas and are recollected in
hoppers. Because settling chambers are effective in removing
only larger particles, usually greater than 50 micron size. They
are used in conjunction with a more efficient control device. They
offer low pressure drop and requires simple maintenance.

26. Cyclone Separators
• The general principle of inertia separation is
that the particulate-laden gas is forced to
change direction. As gas changes direction,
the inertia of the particles causes them to
continue in the original direction and be
separated from the gas stream.
• The walls of the cyclone narrow toward the
bottom of the unit, allowing the particles to
be collected in a hopper.
• The cleaner air leaves the cyclone through
the top of the chamber, flowing upward in a
spiral vortex, formed within a downward
moving spiral.
• Cyclones are efficient in removing large
particles but are not as efficient with smaller
particles. For this reason, they are used with
other particulate control devices.

27. Fabric filters
• Fabric filters, or bag houses,
remove dust from a gas
stream by passing the stream
through a porous fabric. The
fabric filter is efficient at
removing fine particles (0.5
micron) and can exceed
efficiencies of 99 percent in
most applications.
• Filter bags are usually tubular
or envelope shape having
length of bags varying from
1.8 -9m

28. Electrostatic Precipitators (ESPs)
• An ESP is a particle control device that uses
electrical forces to move the particles out of the
flowing gas stream and onto collector plates.
• The ESP places electrical charges on the
particles, causing them to be attracted to
oppositely charged metal plates located in the
precipitator.
• The particles are removed from the plates by
"rapping" and collected in a hopper located below
the unit.
• The removal efficiencies for ESPs are highly
variable; however, for very small particles alone,
the removal efficiency is about 99 percent.
• Electrostatic precipitators are not only used in
utility applications but also other industries (for
other exhaust gas particles) such as cement (dust),
pulp & paper (salt cake & lime dust),
petrochemicals (sulfuric acid mist), and steel
(dust & fumes).

30. Wet Scrubbers
• Main advantage is that simultaneous removal of particles
and gaseous pollutants.

31. Control of gaseous pollutants from
stationary sources
• The most common method for controlling gaseous
pollutants is the addition of add-on control devices
to recover or destroy a pollutant.
• There are four commonly used control technologies
for gaseous pollutants:
– Absorption,
– Adsorption,
– Condensation, and
– Incineration (combustion)

32. Absorption
•The removal of one or more selected
components from a gas mixture by
absorption is probably the most
important operation in the control of
gaseous pollutant emissions.
•Absorption is a process in which a
gaseous pollutant is dissolved in a
liquid.
•Water is the most commonly used
absorbent liquid.
•As the gas stream passes through the
liquid, the liquid absorbs the gas, in
much the same way that sugar is
absorbed in a glass of water when
stirred.

33. • Absorbers are often referred to as scrubbers, and there
are various types of absorption equipment.
• The principal types of gas absorption equipment include
spray towers, packed columns, spray chambers, and
venture scrubbers.
• In general, absorbers can achieve removal efficiencies
grater than 95 percent. One potential problem with
absorption is the generation of waste-water, which
converts an air pollution problem to a water pollution
problem.
• Common absorbent used for removal of SO2 gas are –
sodium, ammonia, calcium and magnesium. Other
absorbent are- MgO, CaO, CaCO3,CCl4 and water etc.

34. Adsorption
• When a gas or vapor is brought into contact with a solid,
part of it is taken up by the solid. The molecules that
disappear from the gas either enter the inside of the
solid, or remain on the outside attached to the surface.
The former phenomenon is termed absorption (or
dissolution) and the latter adsorption.
• The most common industrial adsorbents are activated
carbon, silica gel, bauxite, , molecular Sieves and
alumina, because they have enormous surface areas per
unit weight.
• Activated carbon is the universal standard for
purification and removal of trace organic contaminants
from liquid and vapor streams.

35. Carbon adsorption systems are either regenerative or non-
regenerative.
Regenerative system - usually contains more than one carbon bed.
As one bed actively removes pollutants, another bed is being
regenerated for future use..
Non-regenerative systems - have thinner beds of activated carbon.
In a non-regenerative adsorber, the spent carbon is disposed of when
it becomes saturated with the pollutant..
Regenerative Carbon
Adsorption System
Non-Regenerative Carbon
Adsorption System

36. Condensation
Condensation is the process of converting a gas or vapor to
liquid. Any gas can be reduced to a liquid by lowering its
temperature and/or increasing its pressure.
Condensers are typically used as pretreatment devices. They
can be used ahead of adsorbers, absorbers, and incinerators to
reduce the total gas volume to be treated by more expensive
control equipment. Condensers used for pollution control are
contact condensers and surface condensers.

37. In a contact condenser, the
gas comes into contact with
cold liquid.
In a surface condenser, the
gas contacts a cooled surface
in which cooled liquid or gas
is circulated, such as the
outside of the tube.
Removal efficiencies of
condensers typically range
from 50 percent to more than
95 percent, depending on
design and applications.

38. Incineration, also known as combustion, is mostly used to
control the emissions of organic compounds from process
industries.
This control technique refers to the rapid oxidation of a
substance through the combination of oxygen with a
combustible material in the presence of heat.
When combustion is complete, the gaseous stream is
converted to carbon dioxide and water vapor.
Equipment used to control waste gases by combustion
can be divided in three categories:
Direct combustion or flaring,
Thermal incineration and
Catalytic incineration.

39. • Direct combustor is a device in which air and all the
combustible waste gases react at the burner. Complete
combustion must occur instantaneously since there is no
residence chamber.
• A flare can be used to control almost any emission stream
containing volatile organic compounds. Studies conducted by
EPA have shown that the destruction efficiency of a flare is
about 98 percent

40. In thermal incinerators the combustible waste gases pass
over or around a burner flame into a residence chamber
where oxidation of the waste gases is completed.
Thermal incinerators can destroy gaseous pollutants at
efficiencies of greater than 99 percent when operated
correctly.

41. Catalytic Incinerators are very similar to thermal
incinerators. The main difference is that after passing
through the flame area, the gases pass over a catalyst bed.
A catalyst promotes oxidation at lower temperatures,
thereby reducing fuel costs. Destruction efficiencies greater
than 95 percent are possible using a catalytic incinerator.

42. Global effects of air pollution
• Green House effect
• Acid rain
• Global Warming
• Ozone Depletion or Ozone Holes
• Heat Islands

43. • The ozone layer is becoming thin due to the gases
called CFCS. The use of these gases started in 1930s
in refrigerators, air conditioners, and for cleaning of
computers. These gases do not burn and are not
poisonous. However, CFCS are known to spoil the
ozone layer of the atmosphere in a systematic way.
Modern research shows that one molecule of CFCs
can destroy one lakh molecules of ozone.

44. ENVIRONMENTAL EDUCATION IS
THE NEED OF THE HOURS
• Students must spread awareness among the people on
“environmental issues such as over use of petrol
vehicles, over use of coal, oil and ground water.
Besides, people must be taught not to pollute water
bodies too. If we do not protect our environment, it
will stop supporting organisms. That would be the
end of human life”