Sources of Air Pollution
Air Pollution and Control
Contents of unit-II
• L-3 Sources of Air Pollution : Natural and
• Classification of pollutant.
• L-4 Classification of pollutants, Quantity and
composition of particulate & gaseous pollutant.
• Units of measurement.
• L5 Problems on unit (ppm to µg/m3 and vice
• TEST-1 on Unit-I and Unit- II
Fundamental Causes of Air
• During the last couple of centuries we
witnessed an emergence of several
fundamental trends that became the major
forces behind the dramatic levels of air
• Industrialization set in motion the widespread
use of fossil fuels which are now the main
drivers of pollution as we know it.
• Population growth causes the demand for
food and other goods to go up, which is met
by expanded production and use of natural
resources. This then leads to higher levels of
• Globalization has in a way become a
facilitator of air pollution. Big industry takes
advantage of lapses environmental controls
in developing nations and moves its
manufacturing facilities to such “pollution
havens” from where air pollution travels
around the world without any obstacles.
When we say air pollutants and sources,
above picture comes to our mind
• Any substance occurring in the
atmosphere that may have adverse effects
on humans, animals, plant life, and/or
• Air pollutants have known or suspected
harmful effects on human health and
• A source of air pollution is any
activity that causes pollutants to
be emitted into the air.
• Natural sources of air pollution,
also known as biogenic sources.
• Human-generated pollutants or
Classification of sources of air
pollutant sources- 1st way
1) Natural Sources
- forest fires (CO2, ash)
- volcanic eruptions (sulfur, mercury)
- Biological decay
- Disintegration of rocks
Classification of sources of air pollutant sources2nd way
Eg:- 1. Industrial
2. Power plants
Eg:- 1. Domestic
heating of coal
Eg:- 1. Highway
Eg:- 1. Railway
2. Bus stand
3. Air ports
• "Mobile sources" is a term used to
describe a wide variety of vehicles,
engines, and equipment that generate
air pollution and that move, or can be
moved, from place to place.
• Mobile sources are classified as OnOnroad and Non-road sources.
• "On-road" or highway sources include vehicles
used on roads for transportation of passengers or
freight. On-road sources include light-duty vehicles
Onlight(LDVs, also referred to as passenger cars), heavyheavyduty vehicles (HDVs), and motorcycles that are used
for transportation on the road. On-road vehicles may
Onbe fuelled with gasoline, diesel fuel, or alternative
fuels, such as alcohol or natural gas.
• "Non-road" sources include gasoline and
diesel powered vehicles, engines, and
equipment used for construction, agriculture,
transportation, recreation, and many other
purposes. These sources emit both criteria
pollutants and other hazardous air pollutants.
• Mobile sources pollute the air through
combustion and fuel evaporation. These
emissions contribute greatly to air pollution
nationwide and are the primary causes of air
pollution in many urban areas. Combustion is
the process of burning.
• Motor vehicles and equipment typically burn
fuel in an engine to create power.
• Petrol, Gasoline and diesel fuels are mixtures
of hydrocarbons, which are compounds that
contain hydrogen and carbon atoms.
Difference between perfect combustion
and typical engine combustion
• Perfect Combustion
Fuel (hydrocarbons) + Air (oxygen and nitrogen)
Carbon dioxide (CO2) + water (H2O) +
• Typical Engine Combustion
Fuel + Air Unburned Hydrocarbons + Nitrogen
Oxides (NOx) + Carbon monoxide (CO) +
Carbon dioxide + water
Classification of air pollutants:Based on states of mater
Eg :- CO, NOx, SOx etc
Eg :- Fumes, mist, fog,
smoke, dust etc
• Gaseous pollutants are those
pollutants which gets mixed with
the air and do not normally settle
• Which comprise of finely divided
solids or liquids and often exists in
colloidal state as aerosols
Classification of air pollutants:- Based
on Chemical Composition
Eg :-1. Aldehydes,
Eg :- 1. Carbon compounds- CO,
2. Nitrogen Compounds – NOx, NH3
3. Sulphur compounds- SOx,
4.Oxidising afents – O3
5. Halogens- HF, HCl
Organic and inorganic pollutants
• Organic :- Contains H-C (hydrocarbons)
:H• Inorganic :- Do not contain hydrocarbons
Classification of air pollutants:- Based
Eg :- CO, NO2, SO2,SPM,
Eg :- O3, PAN, Smog,
• Primary air pollutants are those
which are emitted from identifiable
Secondary air pollutants
• Secondary air pollutants are those
which are produced in the air by the
interaction among two or more
primary pollutants or by reaction
constituents with or without photo
SO2 NO NO2
Most NO3 and SO2 – salts
Q1. _____________or ______________ sources
include vehicles used on roads for transportation of
passengers or freight.
Q2. ______________sources include gasoline and
diesel powered vehicles, engines, and equipment
used for construction, agriculture, transportation,
recreation, and many other purposes.
Q3. ________________ pollutants are emitted from
Q4. Ozone is __________________ pollutant.
Q5. Secondary air pollutants need
___________________ for formation.
Q6. ___________ sources pollute the air through
combustion and fuel evaporation.
Q7. Natural sources of air pollution, also known as
Q8. Human-generated pollutants are also known as
Q9. Air port can be categorized under
Q10. Domestic cooking is _________________
type of source
Q1. Explain classification of sources of air
pollution with suitable examples.
Q2. Write detailed classification of air pollutants.
Q3. Define by giving examples
1. Primary air pollutants
2. Secondary air pollutants
3. On-road sources
On4. Non-road sources