2. INTRODUCTION
🞇SYLLABUS
Structure and composition of atmosphere
– Definitions, scope and scales of air
pollution –sources and classification of air
pollutants and their effect on human health,
vegetation, animals, property, aesthetic
values and visibility – ambient air quality
and emission standards.
UNIT - 1
3. INTRODUCTION
• The clean air is very essential for human life and
health. It should be free from pollutants in any form.
The pollutants may be in the form of solid, liquid or
gaseous form. Any considerable change in the
composition of air may affect the living system of the
humans.
• Air pollution is defined as the pollution in the
atmospheric air, due to the presence of solid, liquid
or gaseous material and cause the problems to
humans, living organisms, property, etc.
• A pollutant is defined as a substance which creates
the air pollution in the three states of matter which
affects the atmospheric air considerably and creates
harmful effects on the environment.
4. There are five layers in the structure of the
atmosphere depending upon temperature. These
layers are:
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere
STRUCTURE OF THE ATMOSPHERE:
6. ◾ It is considered as the lowest layer of Earth’s
atmosphere.
◾ The troposphere starts at surface of the earth
and goes up to a height of 12km.
◾ All weather occurs within this layer.
◾ This layer has water vapors and mature particles.
◾ Tropopause (ColdTrap) separatesTroposphere
and Stratosphere.
7. ◾ It is the second layer of the atmosphere found above the
troposphere.
◾ It extends up to 50 km of height.
◾ This layer is very dry as it contains little water vapour.
◾ This layer provides some advantages for flight because it
is above stormy weather and has steady, strong,
horizontal winds.
◾ The ozone layer is found in this layer and it absorbsUV
rays and safeguards earth from harmful radiation.
◾ Stratopause separates Stratosphere and Mesosphere.
8. ◾The Mesosphere is found above the
stratosphere.
◾It is the coldest of the atmospheric layers.
◾The mesosphere starts at 50 km above the
surface of Earth and goes up to 80 km.
◾The temperature drops with altitude in this layer.
◾By 80 km it reaches -100 degreesCelsius.
◾Meteors burn up in this layer.
◾The upper limit is called Mesopause which
separates Mesosphere andThermosphere.
9. ◾ Thermosphere is found above Mesopause from 80 to
500 km.
◾ Radio waves which are transmitted from the earth are
reflected back by this layer.
◾ The temperature increases with height.
◾ Aurora and satellites occur in this layer.
IONOSPHERE:
◾ The lowerThermosphere is called the Ionosphere and It is
positioned between 80 and 500 km above the Mesopause.
◾ Ionosphere consists of electrically charged particles known
as ions.
◾ This layer is defined as the layer of the atmosphere of
Earth that is ionized by cosmic and solar radiation.
10. ◾Exosphere is the outermost layer of the
atmosphere.
◾In the exosphere, an upward travelling molecule
moving fast enough to attain escape velocity
which can escape to space with allowing the
changes of collisions and so here molecules and
atoms escape into space.
◾It extends from the top of the thermosphere up
to 10,000 km.
11. NOTE:
OThe sun radiates its energy in all
directions into space in short
wavelengths, which is known as
solar radiation.
O The energy received by the earth’s
surface in the form of short waves is
termed as Incoming solar radiation
or Insolation.
12. COMPOSITION OF ATMOSPHERE
1. GASES:
Carbon dioxide is a metalorgically very important gas as it is
transparent to the incoming solar radiation but opaque to the
outgoing terrestrial radiation by absorbing the part of it and
reflects back towards the earth surface. The volume of other
gases is constant, but the volume of this gas is rising in the
past few decades.
Gases has also increased the temperature of atmospheric air.
Ozone is an another important component of the atmosphere,
found between 10-50 kilometers above the earth surface. It
acts as a filter and absorbs the UV (Ultra Violet) radiation from
sun and prevents them from reaching the surface of earth’s
atmosphere.
13. 2. WATER VAPOUR:
It is also a variable gas in the atmosphere which decreases
with altitude. When it is in warm and wet of tropics, it
constitutes about 4% of the air by volume and similarly lesser
than 1% of the air by volume when it is in the dry and cold
regions of desserts and polar regions.
It also decreases from the equator towards the poles and it
also absorbs the part of insulation from the sun and prevents
the earth’s radiated heat. It acts like a blanket so as to maintain
the atmospheric temperature to be neither too hot not cold and
it also contributes in stability or instability of air.
3. DUST PARTICLES:
Atmosphere has the capacity to keep the small solid particles
such as smoke, ash, sand, etc. on its surface.
14. DEFINITION
• Air pollution refers to any physical, chemical or biological
change in the air. It is the contamination of air by harmful
gases, dust and smoke. Them composition of gases present
in the atmosphere which gets collapsed .
• Air pollution means the presence of chemicals or
compounds in the air which are usually not present and
which lower the quality of the air or cause
detrimental(harmful) changes to the quality of life leading to
the health risk(such as the damaging of the ozone layer or
causing global warming).
15. The scope of air pollution explained by the three
associations were:
1) Engineering Built Council of USA
2) American Medical Association
3) Indian standard
⦿The types of exposure classified on the three basis
were:
1) Personal exposure
2) Occupational exposure
3) Community exposure
16. CAUSES OF AIR POLLUTION
⚫Population
⚫Industrial development
⚫Radio-active materials
⚫Natural causes
⚫Volcano Eruptions
⚫Increase in transport facilities
⚫Household and Farming Chemicals
⚫Deforestation
⚫Fossil-Fuel Emissions (while mining)
17. SCALES OF AIR POLLUTION
The air pollution problem may occur in
three scales:
1. MICRO SCALES: Few meters (e.g. House)
2. MESO SCALES: Few Hectares (e.g. City/
State)
3. MACRO SCALES: Regional or continental
scale (e.g. Country)
18. SOURCES OF AIR POLLUTANTS
The sources of air pollution can be classified as:
1. Natural sources:
* (NO2) from electrical storms
* HF and HCL from volcanoes
* Air borne particles from soil
2. Manmade sources:
* Burning of fossil fuels
* Deforestation of forest
* Industrial activities
19. CLASSIFICATION OF AIR POLLUTANTS
According to origin:
1. Primary pollutants: The pollutants that are
emitted directly from identifiable sources produced
from natural events. (e.g. dust storms and volcanic
eruptions)
2. Secondary pollutants: The pollutants that
are formed in the atmosphere by chemical
interactions between primary pollutants and
atmospheric constituents. (e.g. Ozone, Sulphuric
acid- by the reaction of sulphur dioxide and water;
Nitric acid – by the reaction of NO2 and water.)
20. CLASSIFICATION OF AIR POLLUTANTS
According to the state of matter:
1. Gaseous air pollutants: These pollutants
are in gaseous state in normal pressure and
temperature. (e.g. NO2 , SO2 ,CO2 )
2. Particulate air pollutants: These are
suspended droplets, solid particles, or the mixture of
both gases and solids.
According to the sources:
1. Natural sources
2. Manmade sources
21. NOTE:
Some of the important air pollutants include:
O Smoke , fog , smog
O Oxides of sulphur & nitrogen
O Fumes, mists, aerosols
O Carbon monoxide (CO)
O Volatile Organic Compounds (VOC’s)
O Lead
O SPM, TSPM (Total Suspended Particulate Matter)
O Hydrocarbons & organic compounds
O Haze, smaze
22. EFFECT ON HUMAN HEALTH
• Some environmental poisons can cause acute illness and even death
or chronic diseases which may take some years to appear.
• Air pollution mainly affect the respiratory system leading to diseases
like bronchitis, emphysema, asthma and lung cancer.
• Lung cancer is caused mainly due to the polluted air containing
carcinogens.
• SO2 is the most serious and wide spread air pollutant causing cough,
shortness of breath, accute irritation to the membrane of the eyes and
also affecting the larynx (voice box).
• CO often affects the oxygen carrying capacity of blood.
• NO3 is reported to be a pulmonary irritant and its tumor
concentration may cause pulmonary haemorrhage.
23. NOTE:
OSmog has a killer effect, which is also the
result of air pollution. In December 1952,
about 4,000 peoples were dead in London
due to smog: Similarly; in 1956, 1957 & 1962
between 700 to 1000 were dead.
OH2S & also a toxic lead (Pb) produced from
the automobile exhausts is a cumulative
poison and it is very hazardous to children
and may even cause brain damage.
24. EFFECT ON Vegetation
Fluorine is the most toxic pollutant for plants which is
taken by them, from the air inhaled is contaminated with
fluorine; produced by the manufacturing process of
aluminum, glass, phosphate fertilizers and clay baking
operations. Its effects on plants include:
• Photo-toxicological effect is obtained , when then intake
concentration of fluorine exceeds about 0.3 µg/m3
• Yield and photosynthesis of crops were reduced.
• Quantities and nutrients present in the plants were
reduced.
25. EFFECTONanimals
The animals which consumes the polluted plants were highly
affected. The important pollutants that affect the animals were:
• Fluorine: Its effects are harmful which includes lack of
appetite, general illness, reduction in growth, fertility and
milk production.
• Arsenic: It creates Arsenic poisoning on animals with
effective symptoms of thirst, vomiting, discomfort, irregular
pulse and respiration.
• Lead: It creates Lead poisoning by the lead emitted from
coal based industries (coke ovens) causing harmful effects
like prostration, paralysis of digestive tract, diarrhoea,
staggering, inability to stand.
26. NOTE:-
OEFFECTONAquaticlife:
Atmospheric gas pollutants such
as CO, CO2, sulphur oxides (like SO2)
and nitrogen oxides (Nox) react with
rain and forms acidic rain (called acid
rain,H2SO4,H2CO3,HNO3) affects fresh
water bodies and aquatic life
(especially fishes) in the water
resources.
27. Effect on property
Air pollution affect various materials and services in the
following ways:
• Corrosion
• Chemical attack (direct and indirect)
• Abrasion
• Deposition and removal
In the urban areas, air pollution causes severe economic
losses by wastage of materials. The atmospheric
deterioration of materials is caused due to moisture,
temperature, sunlight and air movement.
28. EFFECT ON aesthetic values
• Air pollutants cause non-repairable damages to the art
treasures of a country. The Taj Mahal in India, The
Colosseum in Rome, The San Marco Basilica in Venice
have shown signs of decay and corrosion attacks due to
the severe effects of air pollution.
• It can degrade scenic landscapes, and in extreme cases,
completely obscure them. Particulate matter suspended in
the air is the main cause of visibility degradation which
is an environmental quality that is valued
for aesthetic reasons that are difficult to express or
quantify.
29. EFFECT ON visibility
Visibility depends on the transmission of light through the
atmosphere and the capacity of eye to differentiate the
object. It can be reduced due to the pollutants in air depends
on the following factors:
• Size, concentration and physical characteristics of
particulate matter.
• Nature of particulate matter in ambient air.
• Volume of air into which it gets mixed up.
GLOBALENVIRONMENTALISSUES:
• Acid rain
• Ozone Depletion (Ozone hole)
• Global Warming
30.
Ambient air quality refers to the condition or quality of air
surrounding us in the outdoors. National Ambient Air Quality
Standards are the standards for ambient air quality set by the
Central Pollution Control Board (CPCB) that is applicable
nationwide. The CPCB has been conferred this power by the
Air (Prevention and Control of Pollution) Act, 1981.
It is important for any numerical standard that averaging
period, unit, and statistical measure of pollutant released to an
atmosphere. The criteria are specified for a variety of reasons
including for the protection of human health, buildings, crops,
vegetation, ecosystems, and for planning.
AMBIENT AIR QUALITY
STANDARDS
31.
All of the Central and State Pollution Control Boards
are functioning under the control of the Ministry of
Environment and Forest.
Annual Time Weighed Average (ATA) is the
arithmetic mean of minimum site taken twice a
week 24 hours at uniform intervals.
Other Air Quality Standards:
* Point of Impingement Standards
* Soiling Index
* Odour Standards
AMBIENT AIR QUALITY
32. AQI or Pollution Standards Index (PSI), is a uniform
system developed by EPA (Environmental
Protection Agency) of USA; to enable the public to
determine whether the air quality levels in
particular location.
The most important number on this scale is 100,
since the number corresponds to the National
Ambient Air Quality Standard established under
the Clean Air Act, 1970.
AIR QUALITY INDEX
33. When the AQI level is excess of 100, then the
pollutant is higher and leading to a
unhealthy range on a given day.
When the AQI level equals or lesser than 100,
then the pollutant reading is in the
satisfactory range on a particular day.
The AQI of EPA is mainly based on the 5
major air pollutants.
AQI MEASURES
34. NOTE:
The AQI measures five criteria of air pollutants
such as:
OParticulate mater
OSulphur dioxide (SO2)
OCarbon Monoxide (CO)
ONitrogen dioxide (NO2)
OOzone (O3)
And it converts the measured pollutant
concentration in a community’s air to a
number on a scale of 0 to 500.
35. ◾Emission standards are the
legal requirements governing air pollutants
released into the atmosphere.
◾They are generally designed to achieve air
quality standards to protect the human life.
◾Emission standards set quantitative limits on
the permissible amount of specific air
pollutants that may be released from specific
sources over specific timeframes.
EMISSION STANDARDS
36. ◾Emission intensity (Carbon intensity) is the
emission rate of the given pollutant relative to
the intensity of the specific activity, or an
industrial production process.
◾Emission standards are mainly
implemented based on the following two
types of sources production:
1.Emission standards for mobile sources
2.Emission standards for stationary sources
EMISSION STANDARDS
37. Bharat stage emission standards
Bharat stage emission standards (BSES) are
emission standards instituted by the Government
of India to regulate the output of air pollutants
from CI engines and SI engines of vehicles. The
standards and the timeline for implementation are
set by the Central Pollution Control Board under
the Ministry of Environment, Forest and Climate
Change.
These standards were first introduced in 2000
based on the European regulations.
38. Bharat stage emission standards
Emission standards in India have been
adopted for new engines or vehicles on the
following categories:
Cars and Light Trucks –Emissions
Cars and Light Trucks – Fuel Economy
2- and 3- Wheel Vehicles
Heavy-Duty Truck and Bus engines
Non-Road (Off-Road) Diesel Engines
Generator Sets
39. TYPES OF EMISSIONS
Evaporative Emissions. Gasoline, antifreeze, and
other auto liquids are made up of hydrocarbons that
can be released into the air in many different ways.
⚫Refuelling Losses
⚫Exhaust Emissions
⚫Perfect Combustion
⚫Typical Combustion
⚫Carbon Dioxide (CO)
⚫Nitrogen Oxides (NOx)
⚫Carbon Monoxide (CO)
40. EMISSION STANDARDS IN
INDIA
Standard Reference Date
Bharat Stage II Euro 2 1 April 2000
Bharat Stage III Euro 3 1 April 2010
Bharat Stage IV Euro 4 1 April 2017
Bharat Stage VI Euro 6
April 2020 with mandate
(proposed)
