1. CE8005 - Air Pollution and Control
Structure and composition of Atmosphere –
Definition, Scope and Scales of Air Pollution – Sources
and classification of air pollutants and their effect on
human health, vegetation, animals, property,
aesthetic value and visibility- Ambient Air Quality and
Emission standards –Ambient and stack sampling and
Analysis of Particulate and Gaseous Pollutants
2. Air Pollution and Air Pollutant
• Pollution in atmospheric air due to presence
of solid, liquid and gaseous material
• It causes problems to human, living
• Pollutant is the material which creates the air
• Pollutants affect the atmospheric air
considerably and creates harmful effects.
6. Structure and composition of Atmosphere
• Earth’s atmosphere is composed of about 78% nitrogen, 21%
oxygen, and 0.93% argon.
• The remainder, less than 0.1%, contains such trace gases as
water vapor, carbon dioxide, and ozone.
• All of these trace gases have important effects on Earth’s
• The atmosphere can be divided into vertical layers determined
by the way temperature changes with altitude.
• The layer closest to the surface is the troposphere, which
contains over 80% of the atmospheric mass and nearly all the
• The next layer, the stratosphere, contains most of the
atmosphere’s ozone, which absorbs high-energy radiation from
the sun and makes life on the surface possible
7. Structure and composition of Atmosphere
• Above the stratosphere are the mesosphere and
• These two layers include regions of charged atoms and
molecules, or ions.
• The upper mesosphere and lower thermosphere are called
the ionosphere, this region is important to radio
• Because radio waves can bounce off the layer and travel
• There is a thought that the present atmosphere developed
from gases ejected by volcanoes.
• Human activities may be affecting the levels of some
important atmospheric components, particularly carbon
dioxide and ozone.
• Extends about 12 km from earth
• Troposphere consists of 70% of nitrogen and 21% of
oxygen and small % of other gases
• Solar radiation is the main heat from source from sun
absorbed by ground
• As the altitude increases, the temperature decreases
• The rate at which the temperature decreases is
known as Lapse Rate. (approximately
• Tropopause is the top level of troposphere.
• It is the layer just above Troposphere.
• It extends upto 50 km
• Temperature range will be -80 oC to 0 oC from
troposphere to stratosphere
• Increase in temperature is due to absorption of
ultraviolet radiation from the sun by oxygen and
• Little amount of water vapour is also present in this
• Ozone layer is the layer in stratosphere which exists
between 20 km to 40 km above earth’s surface.
• Stratosphere is sometimes called ozonosphere.
• Stratosphere is completely free from clouds
and other forms of weather.
• Polar stratospheric or nacreous clouds are
occasionally seen in lower parts of
• This is the highest layer that a jet-powered
aircraft can be accessed.
• Third layer from Earth’s surface
• Extends from stratosphere about 50 km to 80 km
from ground surface
• It is the coolest place of earth’s atmosphere.
• Has an average temperature of -85 oC
• Top level of mesosphere is known as mesopause
(just below the mesosphere)
• Mesosphere lies above the maximum altitude for
aircraft and minimum altitude for orbital space craft.
• It can be accessed through the use of rockets only.
• Hence it is poorly understood part of atmosphere.
• It is the zone above the mezopause.
• It extends to an altitude about 80 km upto 500 km of
• Height varies considerably due to changes in solar
• Thermopause lies at the lower boundary of exosphere.
• It is also called exobase.
• Lower part of thermosphere contains many ions and free
• Cosmic rays and radiations from the sun produce the
• Hence this part of thermosphere is called ionosphere.
• Outermost layer of atmosphere beyond the
height of 500 km and above.
• It is a low density, high temperature region
with minimum atomic collisions.
• The layer consists of low density H2 , He and
other heavier molecules such s N2, O2 and CO2
closer to exobase.
• The exosphere is located too far above earth.
• Most of the satelites orbiting the earth are
located in exosphere.
15. Important Air Pollution – Oxides of Sulphur
• SO2 and SO3 are pollutants in oxides of sulphur and SO2 is
• SO2 is an irritant gas, it is a major pollutant emitted from
• Increases breathing rate and creates O2 deficiency in blood
• Ashtma patients are affected very worst due to this pollutant.
• SO2 causes acidity in fog, smoke and also in rain.
• Corrodes the buildings and materials.
• When SO2 reacts with O2 it forms SO3 .
• SO3 dissolves in body fluid and forms H2 SO4
• SO3 + H2 O H2 SO4
• H2 SO4 causes high irritation and causes broncho-spasm.
16. Sources of SO2
• Chemical Plants
• Smelting operations
• Burning of fossil fuels
• Thermal power plants
• Open burning of garbage
• Incineration plants of municipalities
17. Limits of SO2
• Indian Ambient Air Quality Standards define
the 24 hours of concentration of SO2 as 50 –
80 μg/m3 .
Methods to measure SO2
- Modified West-Gaeke’s method
- Ultra-Violet Flourescence method
18. Carbon Monoxide
• It is a colourless, odourless, toxic gas.
• It is produced when organic materials (coal,
wood etc.) burnt incompletely.
19. Sources of CO
• When organic materials burnt completely, the
carbon present is completely oxidised and
forms CO2 .
• Incomplete combustion leads to CO
• Exhausts from automobile are the major
sources of CO
20. Effects of CO
• CO2 replaces O2 present in hemoglobin and
forms carboxy-hemoglobin (COHb )
• If COHb is less, it produces little headache.
• If COHb is high it creates difficulty in
breathing, heart problems etc.
• If COHb is more than 50 % it causes death.
• However, CO is not a permanent pollutant and
COs can be converted into other harmless
21. Limits of CO
• Indian Ambient Air Quality Standards define
CO on hourly weighted average basis of 4
• Methods to measure CO
- Non-Dispersive Infra-red method (NDIR
- Spectroscopy method
22. Oxides of Nitrogen (NOx)
• During combustion atmospheric nitrogen reacts with
oxygen at high temperature and forms oxides of
• Oxides of nitrogen are NO (nitric oxide), NO2 and N2
• It is generally expressed as Nox
• Nitric oxide is very harmful pollutant.
• High concentration of nitric oxide causes sudden
• NO2 irritates human eye, nose and creates
discomfort in respiration system.
23. Sources of NOx
• Automobile exhausts
• Incineration plants
• Furnace smokes
• Combustion of fuel at high temperatures
Methods to measure Nox
- Modified Jacab and Hochheiser method
- Gas Phase Chemi-luminescence method
24. Hydrocarbon (HC) and Organic Compounds
• Group of simple compounds consisting of carbon and
• Evaporated from petrol supplies or emitted from
automobile exhaust (when it is not completely burnt)
• Methane (CH4 ) is an important hydrocarbon
produced in nature by decomposition.
• Ambient Air Quality Standards of India sets the limits
on annual concentration of Benzene and Pyrene as 4
μg/m3 and 1 ηg/m3 respectively.
25. Tests for Hydrocarbon
- Gas chromatography based continuous
- Adsorption and desorption followed by GC
- Solvent extraction followed by HPLC / GC
26. Suspended Particulate Matter (SPM)
• Particulate substance present in air may occur in
solid form (dust and smoke) and liquid form (mist,
• Aerosol is a particle larger than molecule, but small
enough to remain suspended in air.
• Dusts are generated by handling or crushing or
grinding of organic and inorganic materials such as
rock, ore, metal, coal, wood, grain etc.
• Total Suspended Particulate Matter (TSPM) is the
particles include both solid and liquid particles of
suspended particulate matter.
27. Sources of SPM in Air
• By natural process like wind, pollen and pores,
volcanic eruption, decomposition of organic
• Human activities of mining, boring of fossil fuels etc.
Tulip anther with many grains
28. Effects of SPM
• Larger particles (size more than 10 μ) will be trapped
by hair and present in lining of nose.
• Particles from 5 μ to 10 μ are also trapped by musus
and they sent back by spitting and swallowing.
• Less than 5 μ reach lungs and cause the following
- Damages lung tissues
- Causes asthma, bronchitis
- Causes cancer
• Smaller particles having size upto 10 μ are called
Respiratory Suspended Particulate Matter (RSPM) of
• upto 2.5 μ are called PM2.5
• Latest Ambient Air Quality Standards of India limited
the annual concentration of PM10 and PM2.5 as 60
μg/m3 and 40 μg/m3 respectively.
• Microscopic particulate materials cause allergic
• Sneezing is one of the symptoms of allergy.
• Emitted all automobiles
• As per Indian Air Quality Standards a maximum of 5
μg/m3 is permitted as annual concentration of lead
Measuring methods of Lead
- ED – XRF (Using Teflon filter method)
- AAS/ICP Method
31. Other Pollutants – Smoke
• Smoke – Resultant incomplete combustion of
carbonaceous materials like coal, oil, tar and
• Consists of carbon particles less than 0.1 μm
• May be condensation aerosol with solid and
32. Other Pollutants
• Fog – Aerosol of liquid droplets near the grounds as
distinct from clouds.
• Fumes – Solid particles generated by condensation
from gaseous state, after volatilization of from
• Mist – Suspended liquid droplets generated by
condensation from gaseous to liquid state or solid
• Smog – Mixture of smoke and fog
• Haze – Suspension of small particles in air which
makes distinct large objects indistinct.
33. Physical Effect of Air Pollution
• Effects on Visibility
• Effects on urban atmosphere and climate
• Effects on atmospheric constituents
34. Effects on Visibiliy
• Visibility depends on transmission of light through
atmosphere and capacity of eye to differentiate the
• Visibility can be reduced by pollutants in air depends
- Size, concentration and physical of particulate matter
- Nature of particulate matter in ambient air
- Volume of air into which it gets mixed up
35. Effects on Urban Atmospheric and Weather
• Urban air pollution may be caused due to
- Other aerosols
- Due to air pollution, solar radiation is reduced
36. Effects of Atmospheric Constituents
• Main source of organic carbon in bio-sphere is
• Due to combustion of fuels, atmospheric CO2
is increased rapidly.
-CO2 increases ambient temperature
- Increases infra-red absorption
- Increases green house effect
37. Effect of air pollution on human health
• Particles of small size 5 μ penetrate human
lungs and deposited.
38. Effect of air pollution on human health
S. No. Air Pollutant Properties Sources Effects on
1 SO2 Colourless gas Combustion of
2 CO2 Colourless and
39. Effect of air pollution on human health
S. No. Air Pollutant Properties Sources Effects on
3 NOx Reddish brown gas
lungs and nose
4 CO2 Colourless gas Combustion of
coal, diesel and
5 SPM Solid particles (dust and
Liquid particles (mist
40. Effect of air pollution on human health
S. No. Air Pollutant Properties Sources Effects on human
6 Head (heavy
Colourless Vapour Leaded petrol in
the food, water,
soil or dust
7 Ozone (O3 ) Colourless gas Secondary
sneezing, chest pain
8 Nuclear wastes Invisible
41. Effects of Air pollution on Plants
• Pollutant cause effect on plant is Flourine.
• Flourine is mixed with air by
- Manufacturing process of Aluminium, Glass
and phosphate fertilisers
- Clay baking operations
42. Effects of Air pollution on Plants
• Reduces yield crop
• Reduces photosynthesis of plant
• Reduces quantities and nutrients in vegetable,
• Creates harmful effect on animals and human
health, who use the affected plants.
43. Effects of Air-pollution on Animals
• The important pollutants of animals are,
- Reduces milk production
- Lack of appetite
- Reduced fertility
- Growth reduction
45. Effects of Air Pollution on Materials
S. No. Air Pollutant Other factors Materials Effects
1 SO2 , Acids and Gases With moisture Building
2 SO2 , Acids and Gases With moisture
3 SO2 , Acids and Gases With sunlight
4 SO, Acids and Gases With moisture
Textiles Reduction in
5 Oxidants With sunlight Rubber Reduction in
6 SO2 , H2 S and SPM With sunlight
46. Economic Effects on Air Pollution
• Wastage of fuel through improper combustion
• Vegetation and planting damaged due to pollutants such as
smog, dust etc.
• Non repairable damages to art-treasures of country
(Tajmahal, Colosseum in Rome, San Marco Basilica in Venice
• Low power electrical conduits sensitive with air pollution lead
to malfunctioning of equipment
• Paper industry is affected. Paper becomes brittle and difficult
to fold due to the effect of SO2.
• Additional lighting required to improve visibility. Power loss.
• Glass materials and ceramic materials are highly affected to
47. Economic Effects on Air Pollution
• Leather industries and rubber tyred wheels
get cracked, due to contact with atmospheric
48. Effects of Nuclear Power Reactors
• Nuclear reactors doesn’t produce air pollution.
• Nuclear reactors doesn’t produce carbon di oxide.
• Emissions from fossils fuels while burning pollute the
• Nuclear wastes from radio active emission cause
• Nuclear waste cause mutation, death.
• Nuclear weapon testing, nuclear operation of nuclear
reactors needs skill and practice.
• Nuclear reactors are operated in controlled manner.
49. Acid Rain
• Rain pH value equal to or less than 5.6 has harmful effects on
humans, animals, plants, aquatics and infrastructure.
• Normal rain has the pH value of 6.9 (little acidic), when
atmosphere is free.
• When concentration of SOx, NOx, CO2 increase in atmosphere,
the rain water becomes more acidic.
• Sometimes, pH value may be less than 5 or 4.
• The primary pollutant which causes 2/3 of the acid rain is SO2.
• SO2. produced by the burning of coals and oils largely used
for generation of heat and power in industries and domestic
50. Ozone Depletion
• Reduction of thickness of ozone layer due to attach
of chemical pollutants.
• Ultraviolet radiation are highly harmful to all kinds of
life on earth.
• If UV rays are not filtered, it creates impacts to
human, animals and plants.
• Extreme effect of UV radiation is mutation of DNA
• Skin cancers, deadly melenoma.
51. Causes of Ozone Depletion
• Use of CFCs
• Nuclear tests
• Supersonic transports, rockets and space
• Nitrogeneious fertilizers
52. Ozone Hole
• Ozone layer is also known as ozone depletion
• Thickness of ozone layer is less than 150 DU (Dobson
Unit) (1 DU = 0.01 mm)
• Ozone hole may permit the UV radiation to reach the
• UV radiations are highly harmful.
• The maximum area covered by ozone hole was found
about 30 million km2 in September 2000.
53. Global Warming
• Increase of earth’s average temperature due to effect of green
• Green houses are from burning of fossil fuels or deforestation.
• Global warming is a type of green house effect.
• The climate of earth is influenced by 10 to 12 km from earth’s
• During past few years, earth’s climate has been changed to
be getting hotter and hotter year after year.
• If earth is viewed from space, the climate layer of atmosphere
would be a thin layer like a skin or an onion.
• Earth is surrounded by gaseous cover and atmosphere
provides oxygen to living things and maintains heat balance
55. Air Quality Standards
• Assesses current or historical air quality
• Develop long term air management stragegies
and evaluate the progress
• Air regulatory development
• Guide decisions for permitting of new or
56. Steps in Air Quality Standards
• Prepare the air quality criteria
• Air Quality criteria indicates the relationship
between pollutant concentrations in the air. It
is also called as Guide.
• Develop quality goals from quality criteria.
• Complete elimination of air pollution is not
• Some level of pollutants are permitted in
57. Ambient Air Quality Standards
• Legal limits placed on the concentration of air pollutants in a
community where the people and things are exposed.
• First Ambient Air Quality Standards was adopted by Central
Pollution Control Board (CPCB) during 1982.
• Agencies responsible for air quality standards are Central
Pollution Control Board (CPCB) and State Pollution Control
• Both CPCB and SPCB are functioning under Ministry of
Environment and Forest (MoEF)
58. Annual Time Weighted Average
• Arithmetic mean of minimum 104 measurements in
a year of a particular site taken twice a week 24
hourly at uniform intervals.
• 24 hourly or 8 hourly or 1 hourly monitored values as
applicable shall be complied with 98% of the time in
59. Other Air Quality Standards
• Point of Impingement Standards
• Soiling Index
• Odour Standards
• Visibility Standards
• Standards for Particulate Matter Deposited
60. Emission Standards
• Emission standards are applicable for all national ,
regional and local emitters.
• Emission standards are designed to protect human
• Emission intensity is the emission rate of a given
pollutant relative to the intensity of specific activity
such as industrial production process.
• Types of emission standards
- Emission standards for Mobile standards
- Emission standards for stationary sources
61. Emission Sources for Mobile Sources
• Mobile sources are ships, aircraft, automobile, locomotives in
• Bharath Stage Emission standards instituted by Govt. of India
is to regulate the pollutants for motor vehicles.
• The standards are set by CPCB under MoEF.
• The standards based on European standards were established
• Progressively stringent norms have been rolled out.
• Till 2014 the country was under the combination of Euro 3
and Euro 4
• Euro 6 norms are planned by April 2020
62. Emission Standards for Stationary Sources
• Stationary site
The emission standards also include
• Buffer zones
• Stack height
• Design of equipment
• Fuel composition
63. Sampling Analysis
• To measure quality and quantity of pollutant
• To determine the effect of emissions through out the
• To know the nature of source of pollutant
• To determine the effect of emission in different zones
• To estimate single pollutant and multiple pollutant
• To determine the method fo control of air pollution
• To implement the local air pollution control system
64. Air Sampling Analysis
• Gas composition analysis
• Moisture content determination
• Temperature analysis
• Pressure and velocity analysis
• Simplest method of sampling
• Adopted for particles whose diameter exceeds
• Can be sampled by placing in open container
• Sedimentation collectors are made up of glass,
stainless steel and polyethylene
• Used for dust particles less than 10μ
• Particles less than 10μ are known as suspended particles.
• Suspended particles are removed quantitatively from gas
stream flowing through dense material.
• Result of filtration process depends upon filter material.
• The following factors are to be considered for selecting filter
- Type of particulates to be collected
- Chemical nature of filter
- Efficiency of collection
69. Impingement Methods
• Separation of particulates from a gas-stream by collision
against a flat surface.
• The instruments used are
- Dry impinger
- Wet impinger
- Also known as impactors
- Collection of particles by impaction on dry
- Collection of particles by impinging them on a liquid sub-
70. Thermal Precipitation
• Gas containing suspended particles brought into
contact with hot surface.
• Dust free space developed between surface an
• It is due to the thermal force of action.
• It causes particles to migrate from high temperature
zone to low temperature zone.
• Great range of particle size of 0.01 μ to 10 μ
• Low sampling rate of 0.02 to 0.2 litres/min.
71. Electrostatic precipitation
• The gas passes between two electrodes charged to a
potential difference of 10 to 40 kV.
• The electric discharge between the electrodes will
emit electrons and ions from negative electrode.
• It will be drawn towards the positive electrode.
• Particles are separated from the gas stream.
• Collection of 100% particles over a reasonable length
• Particle diameter ranges from 0.2 μ to 10 μ.
72. Centrifugal methods
• It works on the principle of cyclone.
• Dust laden air is directly tangentially to a
cylindrical chamber, in which it forms a vortex.
• The centrifugal force drives the suspended
particles to the wall of cyclonic body.
• From the cyclonic body, the dusts drop into
the collection chamber.
• An axial outlet is provided for the clean gas.
73. Thank you
Dr A R Pradeep Kumar, B.E., M.E., Ph.D.
Professor and Head/Mech.
Dhanalakshmi College of Engineering, Chennai
email : email@example.com
99 41 42 43 37