Air pollution

AIR
POLLUTION
1
PREPARED BY:
Prof. KHUSHBU K.
SHAH
Assistant Professor
SSASIT

AIR POLLUTION
DEFINITION
 AIR POLLUTION :-Means any solid , liquid, or
gaseous substance ( including noise ) present in the
atmosphere in such concentration as may be or
tend to be injurious to human beings or other living
creatures or plants or property or environment
 AIR POLLUTANT :-the substance which creates
pollutant is called pollutant
2

AMBIENT AIR QUALITY STANDARDS
3

AMBIENT AIR QUALITY STANDARDS
4

CLASSIFICATION OF AIR POLLUTANTS
A - Classification based on origin of pollutants :
1) PRIMARY POLLUTANT
2)SECONDARY POLLUTANT
1) Primary Pollutant:-
- Emitted directly from
the
the sources and are found in the
atmosphere in form in which they
fumes,
were
mist,
emitted,
sprays,like SOx, NOx, HC, ash, smoke, dust
radioactive compounds etc
2) Secondary pollutants:-
- These are formed in atmosphere by chemical interaction between
primary pollutants and atmospheric constituents,
like ozone, SO3, peroxyacyl nitrate ( PAN ) , aldehydes, ketones ,
etc
5

PRIMARY & SECONDARY POLLUTANTS
Type Primary Secondary
(i) Sulfur Compounds
(ii) Nitrogen
compounds
(iii) (a) Carbon Oxide
(b) Carbon
Containing
compounds
(iv) Fluoride compounds
(v) Oxidants
SO2,H2S
NO,NH3
CO,CO3
C1,C5
HF
None
SO3,H2SO4
N2.HNO3
None
Adehydes, kentones
None
O3
6

CLASSIFICATION OF AIR POLLUTANTS
B – Classification according to the states of matter :
1) GASEOUS POLLUTANTS
2) PARTICULATE AIR POLLUTANTS
1) Gaseous pollutants:-
- These pollutants are in gaseous state,
like , CO, CO2, NOx, SOx, HC, Photochemical oxidants, fluorine, chlorine,
H2S, CH4, etc , and have different residence time in atmosphere
2) Particulate pollutants:-
- They are in suspended form in the atmosphere and their
residence time depends upon the size of particulate matter .
These are in the form of dust, smoke, fumes, mist, flash, soot,
along with natural particulates , like , pollen grains, volcanic dust,
fungal spores, protozoa.
7

SOURCES OF AIR POLLUTANTS
SOURCES ARE MAINLY DIVIDED INTO
a) Natural sources :-
1.
2.
3.
4.
5.
Dust storms
Forest fires
Volcanoes
Sea spray
Plant pollen
b) Man made sources :-
1.
2.
3.
Domestic
Industrial
Traffic
8

a) NATURAL AIR POLLUTANTS
 Air pollutants like methane, CO2, H2S etc
emitted into atmosphere through biological
processes, volcanic eruptions, forest fires,
natural gas seepage
 Air pollution from natural sources is a
continuous phenomenon because of its
natural processes.
cyclic
 Man’s role is least to control such natural
pollution
 But he can aggravate such pollution by
disturbing natural and ecological balances
9

b) MAN MADE SOURCES
Point or stationary sources :-Example of point
sources is an industrial unit which adds pollutant to
air at particular points from their tall chimneys.
Pollutants from such point sources affect only
restricted areas.
Line or mobile sources :- The line or mobile
sources of air pollution are the automobile as these
add pollutants along a narrow belts and aver long
distance.
 Area sources :- Town & cities add smoke and gases
over wide areas and so it is called as area sources of
air pollution.
10

Line sources/mobile sources
12

AIR POLLUTANTS – SOURCES AND EFFECTS
•
•

-
Carbon Monoxide(CO):-
Color less, odorless ,taste less and highly stable gas.
It seriously affects the human metabolism.
SOURCES:-
Natural processes such as volcanoes, natural gas emissions, marsh gas
production, etc . Contribute to CO in atmosphere.
- Transportation sources contribute 64% of CO in air.
- Forest fires and agricultural burning contribute about 17%of CO in
atmosphere.
- Industrial processes contribute 9.6% of CO in air.
 EFFECTS:-
- It reduces the oxygen carrying capacity of the blood,
- It reduces the vision ,
- CO is a very dangerous and its high levels are fatal to human life.
15

•
Carbon dioxide (CO2):-
The content of CO2 in the air has increased by approximately
during the last century .
15%
 SOURCES:
- Fossil fuel combustion.
- Jet planes use O2 and release CO2.
- Agricultural practices .
- Forestry.
 EFFECTS:
- CO2 causes nausea and headache.
- It major effect is on the climate of earth.
16

Oxides of sulphur (SOx):
• There are six different gaseous compounds of ‘S’, but the most
prevalent are SO2 and SO3 as they form H2SO3 (Sulfurous acid) and
H2SO4.
SOURCES:
Volcanic activities and other natural sources
Burning of solid and fossil fuels.
Transportation
Industries , Refineries , Sulphuric acid plants.
Open burning of refuse and municipal incinerator.

-
-
-
-
-
 EFFECTS:
- Accelerates the decay of building material, paints,
statues, sculptures.
monuments,
- High concentrations of so2 suffer choruses, metabolic inhibition ,
plasmolysis and even death.
17

Oxides of Nitrogen:
• Primary pollutants released from industrial and automobile
composition are NO and NO2
There are 7 oxides of Nitrogen(N2O,NO,N02,NO3,N2O4and N2O5)
Responsible for formation of smog
NO2 is most toxic.
SOURCES:
Fuel combustion in automobiles and industries.
Lightening.
Forest fires.
Natural ionizing radiations.
EFFECTS:
It reduces the oxygen carrying capacity of blood
Water quality deterioration, produce toxic chemicals on reaction with
organic compounds, and visibility impairment.
NO2 is more toxic.
•
•
•

-
-
-
-

-
-
-
18

Hydrocarbons (HC):-
• The gaseous and volatile hydrocarbons are mainly responsible for air
pollution
•

Common hydrocarbons include methane ,ethylene ,acetylene ,
SOURCES:
Coal fields.
Natural fires.
Incomplete combustion from car engines.
Coal waste fires.
etc.
-
-
-
-
 EFFECTS:
- Some hydrocarbons have carcinogenic and lachrymatory.
- Some harmless hydrocarbons like ethylene , it reacts in the presence
of sunlight and other like nitrogen oxide are harmful.
20

Particulate air pollutants:-
• It is small , solid particles and liquid droplets present in the
atmosphere in very large
In size particulates ranges
dia.
In course particles
In fine particles
EFFECTS ON HEALTH:-
numbers.
from 0.02micron in dia. To a 500 micron•
• :2.5 µm
: ≤ 2.5 µm

-
-
Smaller particles more potential to health damages.
Increased respiratory symptoms, such as, irritation of the airways,
coughing, difficulty in breathing, decreased lungs function,
aggravated asthmas, chronic bronchitis.
Non fatal heart attacks.
Premature death with heart or lungs diseases
Major Cause of reduced visibility, damage materials like statues
and monuments.
-
-
-
21

Natural particulates:-
• Natural particulates are pollen grains , spores bacteria viruses,
protozoa, fungal spores and volcanic dust.
 SOURCES:
- volcanic eruption , blowing of the dust , soil by the wind,
spraying of salt .
- Anthropogenic sources like Fly ash from power plant, melting
and mining operation .
 EFFECTS:
- Particulates less than 10 (µm) can enter deep into the lungs
and may also get into blood stream.
- It accelerate corrosion of metal, damages buildings ,paint etc.
- Particulates in atmosphere reduces visibility , influence the
climate through formation of clouds.
22

Ground Level Ozone
•At upper level, ozone shields Earth from sun’s harmful UV
rays
•At ground level, ozone is harmful pollutants
 SOURCES-formed from car, power and chemical plant
exhaust
 EFFECTS-irritate respiratory system and asthma;
reduces lung function by inflaming and damaging lining
of lungs
23

Particulates
Particulates Size (µm)
• Dust 1 to 200
• Fumes 0.1 to 1
• Smoke 0.1 to 1
• Fly ash 10 to 1000
• Sprays 1 to 1000
• Mists < 10
• Soot 1 to 10
24

Physical state of pollutants or particulate air
pollutants
Dusts:- are small particles of solids resulting from the
breakup of larger particles by operations such as crushing
grinding, and blasting.
Smoke:-It is an aerosol of very fine carbon particles of size
range from 0.1 to 1.0 (µm) which are produced by incomplete
combustion of organic particles such as coal, wood etc.
Soot:- Soot is agglomeration of carbon particles of size 1 to
10 (µm) impregnated with tar, formed due to incomplete
combustion of carbonaceous materials.
Fumes:- Fumes are the fine solid particles formed by
condensation of gaseous state after volatilization. The size
range of particles is 0.1 to 1 (µm)
25

Physical state of pollutants or particulate air
pollutants
Mist:- Mist is an aerosol of liquid droplets formed by the
condensation of vapor volatilization. The size range of natural
Mist are from less than 1 (µm)
Fog:- Water mist is called fog. It is the mist in which the
liquid is water (sufficiently dense to obscure visibility). It is a
visible aerosol.
Smog:- Smoke + fog is expressed as smog.
Gas:- Gas is a matter which is having neither independent
shape or volume and tending to expand indefinitely.
Vapor:- Gaseous phase of matter which normally exist in a
liquid or solid state
27

Effects:
 Premature death
 Aggravated asthma
 Acute respiratory symptoms
 Chronic bronchitis
 Decreased lung function (shortness of breath)
 People with existing heart and lung disease, as well as
the elderly and children, are particularly at risk
29

 Around 30-40% of cases of asthma and 20-30% of all respiratory
disease.
 Effect our health in many ways with both short term and long term
effect.
 Short term effect are: irritation to nose, eye, throat, bronchitis,
headache etc.
 Long term affect are: lung disease, chronic respiratory problem,
damage to heart, brain, eyes etc.
 Eye irritation due to NOx, O3, PAN, particulates.
 Nose and throat due to SO2, NOx etc.
30

 Gaseous pollutants like H2S, SO2, NO2 and hydrocarbons cause
odor nuisance.
 Irritation of respiration tract caused by SOx, NOx, CO, O3.
 Increase in mortality.
 High conc. of SO2, NO2 and SPM causes bronchitis and asthma.
 CO and NO react with hemoglobin and reduce O2 carrying
capacity of blood.
 Heavy metals like lead can cause poisoning. High conc. cause
damage to liver and kidney.
31

 Decrease yield in agriculture.
 Suppressed growth of vegetables.
 Leaf injury and damage to young plants.
 Decreased growth rate and increased death rate.
33

 Corrosion of metals due to SO2 in presence of oxygen and moisture
is converted into H2SO4 acid.
 H2SO4 acid react with limestone, marble and other building
materials to cause deterioration.
 Soiling and eroding of building materials.
 SO2, O3, H2S and aerosols damage protective coating and paints of
the surface.
 O3 and PAN causes cracking of rubber and various electrical
insulations.
 Deterioration of art work due to SPM. 34

Common atmospheric pollution sources
and their pollutants
Category Source Air pollutants
Agriculture Open burning Suspended
particulate matter
(SPM), carbon
monoxide (CO),
volatile organic
compounds (VOC)
Mining and
quarrying
Coal mining, crude
oil and gas
production, other
mining and
quarrying
SPM, SO2, NOx, VOC
Power generation Electricity, gas steam SPM, SO2, SO3, Pb,
Nox, VOC
Transport Combustion engines SPM, SO2, NOx,
VOC, lead (Pb)
35

Category Source Air pollutants
Fertilizers Ammonia, urea, NH3, F, Urea dust,
phosphates NOx
fertilizers plants
Domestic House hold fuel SO2, NOx, Radon,
burning CO, CO2, HC
Chemicals Production of Mercaptans, Nox,
organic, inorganic SO2, H2S, CS2, SPM
chemicals
Nuclear energy Nuclear reactors Radio-active
substances
Mineral processing Cement, smelters, SPM, Mineral
stone crushing, constituents
Community service Municipal SPM, SO2, NOx, CO,
incinerators VOC, Pb
36

Air Pollution Episodes:
 Meuse valley (Belgium):
 December-1930, Experienced severe 3-day fog and temp, inversion, 60
People died and several hundred became ill.
Donora(U.S.A.)
 October-1948, anticyclone weather conditions characterized by no air
movement for 4 days with temp. inversion and fog, 20 People died and
6000 out of 14000 population became ill due to respiratory diseases and
irritation of eyes.
London(England)
 December, 5-9 1952; anticyclone weather with subsidence inversion and
fog along with stagnant air, smoke and SO2,4000 people died and several
thousands hospitalized for respiratory troubles.
 Jan, 1956 and December,1962-hundreds of People died.
37

CONT…
Bhopal (India)
 December, 3rd, 1984-30 tones of deadly Methyl Iso cynate
(MIC) gas was released from storage tank, more than 2500
People died,1 lack People severely affected.
Los Angeles (U.S.A)
 1945-Under stable atmosphere with air pollutant emissions
from thousands of vehicles and temp. inversion resulted in
formation of photo chemical smog and proxy acetyl nitrate
(PAN) , caused reduction in visibility, irritation to eyes and
damage to vegetation.
38

FACTOR AFFECTING AIR
POLLUTION
1) Metrological parameters
- primary parameters are:-
a) wind direction and speed
b) Temperature
c) Mixing height
d) Atmospheric stability
- Secondary parameters:-
or characteristics:-
a) Precipitation
b) Humidity
c) Solar radiation
d) Visibility
39

2) Topographical features:-
- Like unevenness of the land forms and obstacles or barrier like
mountain etc which can obstruct air flow.
3)
-
Characteristics of pollutants :-
Type and size of pollutants and their interactions affects the
distribution and effects of pollutants on human beings,
animal.
4)
-
Mode of release of pollutants :-
For example air pollutant from point source affects a localize
area while air pollutants from a non point source or line
source can affect greater area.
40

CONTROL OF AIR POLLUTION
Controlling measures for air pollution can be mainly divided in to
1. Preventive measures
2. Control measures
1) preventive measures :-
These measures are mainly aimed at correction right at the sources.
Some of the important preventive measures are
1) Selection of suitable fuel
-Using low sulphur coal in power plants,
-Using natural gas in place of coal for power generation ,
-Using LPG/CNG instead of diesel or petrol
Modification in industrial processes and equipments
Selection of suitable site and Zoning for industrial unit
2)
3)
4) By using proper environmental impact studies before setting the
industry.
41

2)Control measures :-
• when it is not possible to control air pollution at source some
measure are to be adoption to control the level of pollution.
• The most common method of eliminating or reducing
pollutants to an acceptable level include.
1. Collecting the pollutants by using
equipment .
2. Destroying the pollutants by thermal
Changing the pollutants to a less toxic
form.
3. By releasing the pollutants through tall chimneys for greater
dispersion..

42

Control of Gaseous pollutants
The gaseous pollutants can be controlled through the techniques
of combustion , absorption and adsorption.
In combustion process oxidizable gaseous pollutants are
completely burnt at a high temperature . It mainly use for
petro chemical , fertilizer , paint and varnish industry.
In absorption technique effluent gases are passed through
absorbers containing liquid absorbent that remove ,treat or
modify one or more gaseous pollutant .
In Adsorption , the air pollutants are adsorbed on a solid
surface . Commonly used adsorbents are activated carbon
,activated alumina, silica gel etc.
1.
2.
3.
43

Control of automobile Exhaust
Automobile exhaust can be controlled by:
By using efficient engines.a)
b) Catalytic converter can convert NO to
reduce potential hazards of NOx .
Using lead free petrol.
By using cleaner fuel like CNG.
By proper maintenance of vehicles.
nitrogen gas and
c)
d)
e)
f) Developing good mass transportation facility.
44

GRAVITATIONAL SETTLING CHAMBER
 Used to remove particles with size greater than 50
μm.
 Velocity of flue gas reduced in large chamber.
 Particles settle under gravitational force.
45

Advantages
1. Low initial cost.
2. Easy to design.
3. Low pressure drop.
4. Low maintenance cost.
5. Dry and continuous disposal of solid
particulates.
Disadvantages
1. Require large space.
2. Less collection efficiency.
3. Only larger size particles can be collected.
46

CYCLONE SEPARATOR
 Centrifugal force is utilized to separate the
particulate matter.
 It can remove 10 to 50 μm particle size.
 Used mostly in industries.
47

Advantages
1. Low initial cost.
2. Require less floor area.
3. Simple construction and maintenance.
4. Can handle large volume of gas at high temp.
Disadvantages
1. Requires large head room.
2. Less efficiency for smaller particles (<10μm).
3. Sensitive to variable dust load and flow rate.
48

ELECTROSTATIC PRECIPITATORS
Works on the principle of electrical charging of
particulate Matter (-ve) and collecting it in a +ve
charged surface.
 99% efficiency.
 Can remove particle size range of 0.1 μm to 1 μm.
49

Advantages
1. High collection efficiency.
2. Particles may be collected dry or wet.
3. Can be operated at high temp. (300-450˚c).
4. Maintenance is normal.
5. Few moving parts.
Disadvantages
1. High initial cost.
2. Require high voltage.
3. Collection efficiency reduce with time.
4. Space requirement is more.
5. Possible of explosion during collection of combustible
gases or particulates.
51

FABRIC FILTERS
 Flue gas is allowed to pass through a woven Fabric,
which filters out Particulate matter.
 Small particles are retained on the fabric.
 Remove particles up to 1 μm.
 Its efficiency up to 99%.
52

Advantages
1. Higher collection efficiency for smaller than 10
μm particle size.
2. Performance decrease becomes visible, giving
prewarning.
3. Normal power consumption.
Disadvantages
1. High temp. gases need to be cooled.
2. High maintenance and fabric replacement cost.
3. Large size equipment.
4. Fabric is liable to chemical attack.
53

SCRUBBERS
 Particulate matters are incorporated into liquid
droplets and removed from the gas stream.
 Different types of scrubbers are-
 - Spray tower
 - Venturi scrubber
 - Cyclone scrubber
 Flue gas made to push up against a down falling
water current.
 Particulate matter mix up with water thus falls
down and gets removed.
54

Spray tower
Cyclone scrubber
55

Advantages
1. Simultaneously remove particulates and gaseous
pollutants.
2. Hot gases can be cooled down.
3. Corrosive gases can be recovered and neutralize.
Disadvantages
1. Lot of waste waters produced.
2. Poses freezing problem in cold countries.
3. Maintenance cost is high when corrosive materials
are collected.
56

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