Air Pollution and Control
• Vehicle emissions control is the study and
practice of reducing the motor vehicle
emissions -- emissions produced by motor
vehicles, especially internal combustion
• Emissions of many air pollutants have been
shown to have variety of negative effects on
public health and the natural environment.
Emissions that are principal pollutants of
• The Combustion Process
• Gasoline and diesel fuels are mixtures of
hydrocarbons, compounds which contain
hydrogen and carbon atoms. In a "perfect"
engine, oxygen in the air would convert all the
hydrogen in the fuel to water and all the
carbon in the fuel to carbon dioxide. Nitrogen
in the air would remain unaffected. In reality,
the combustion process cannot be "perfect,"
and automotive engines emit several types of
• "Perfect" Combustion:
• FUEL (hydrocarbons) + AIR (oxygen and
nitrogen) ==>> CARBON DIOXIDE + water
+ unaffected nitrogen
• Typical Engine Combustion:
• FUEL + AIR ==>> UNBURNED
HYDROCARBONS + NITROGEN OXIDES
+ CARBON MONOXIDE + CARBON
DIOXIDE + water
• Exhaust Pollutants
• HYDROCARBONS: Hydrocarbon emissions
result when fuel molecules in the engine do not
burn or burn only partially.
• Hydrocarbons react in the presence of nitrogen
oxides and sunlight to form ground-level ozone, a
major component of smog. Ozone irritates the eyes,
damages the lungs, and aggravates respiratory
problems. It is our most widespread and intractable
urban air pollution problem. A number of exhaust
hydrocarbons are also toxic, with the potential to
• NITROGEN OXIDES (NOx): Under the
high pressure and temperature conditions
in an engine, nitrogen and oxygen atoms in
the air react to form various nitrogen
oxides, collectively known as NOx. Nitrogen
oxides, like hydrocarbons, are precursors to
the formation of ozone. They also contribute
to the formation of acid rain.
• CARBON MONOXIDE (CO): Carbon
monoxide is a product of incomplete
combustion and occurs when carbon in the
fuel is partially oxidized rather than fully
oxidized to carbon dioxide (CO2). Carbon
monoxide reduces the flow of oxygen in the
bloodstream and is particularly dangerous to
persons with heart disease.
• CARBON DIOXIDE (CO2): In recent years,
the EPA has started to view carbon dioxide, a
product of "perfect" combustion, as a pollution
concern. Carbon dioxide does not directly
impair human health, but it is a "greenhouse
gas" that traps the earth's heat and contributes
to the potential for global warming.
• Particulate matter – Soot or smoke
made up of particles in the micrometre
size range: Particulate matter causes
negative health effects, including but not
limited to respiratory disease.
• Sulphur oxide (SOx) - A general term for
oxides of sulphur, which are emitted from
motor vehicles burning fuel containing a
high concentration of sulphur.
1. AIR TO FUEL RATIO
• A/F ratio is important engine variable to
control auto exhausts.
• Leaner mixture reduces HC and CO but
• Richer mixture increases HC but reduces
H-C and CO increases
14.7 – 1 AFR
H-C and CO
2. Catalytic Converters
HC and CO
Exhaust Flow from engine through converter
• The catalytic converter is a device placed in
the exhaust pipe, which converts
hydrocarbons, carbon monoxide, and NOx
into less harmful gases by using a
combination of platinum, palladium and
rhodium as catalysts.
• Reduces emissions.
• Increases fuel efficiency.
3. PUC i.e. Emission Testing
• Pollution Under Control (PUC)
-Under Rule 115 (7) of Central Motor Vehicle Rules
(CMVR), 1989, motor vehicles are required to carry
PUC Certificate to be given by an agency
authorised for this purpose by State Govt.
• Measurement of emissions from petrol vehicle is
done by gas analyzer and in case of diesel vehicle
emission are measured by smoke meters. There is
a list of approved vendors and models of PUC
equipment which is compiled and circulated by
-To ensure that the in-use vehicles are maintained
well and less emitting
•Gasoline vehicles are tested for Idle CO emission
•Diesel vehicles are tested for Free acceleration smoke
4. Cleaner fuels
• The fuels used these days in cars has
many compounds, which can cause
impurities. You will have to keep your car
clean and try to remove all the sulphur
from the fuel. You must use fuels like
ethanol, methanol and hydrogen, because
all these fuels have a clean burning. These
fuels have low carbon content as
compared to gasoline and diesel. Use
5. Reduce Driving
• Many of us are still dependent on the fossil fuels
and the numbers of cars that are on the road are
increasing everyday. If you take some measures to
drive less, then it can help in curbing the vehicular
pollution and protect some of our natural
• You can maintain your vehicle in a proper manner,
so that there is no harmful emission coming from
your car. Drive as little as possible, use the public
transport or you can walk towards your destination
if it is close by.
6. Maintenance Tips for Vehicles
1. Drive moderately; avoid speeding your
vehicle and stopping frequently, because
this will help in reducing the fuel use and
2. Follow simple vehicle maintenance, like
regular oil changes, spark plug-replacement
and air filter changes. This will increase the
life of your vehicle and will improve the
fuel economy as well.
3. When you start your vehicle, the engine of
the car tends to burn more fuel. However, if
you leave your engine idle for more than
two minutes, then it burns more fuel than
what is required when you start the engine.
Switch off engine at signals if period is
more than 1.5 mins.
4. During the summer seasons, park your car in
a shaded and cooler area, this will minimize
the evaporation of the fuel.
7. Use of Electric cars
• Use of Zero emission
vehicles such as ‘hybrid
cars’ or ‘electric
8. Awareness and legislation
• Creating awareness in public will help in
reducing air pollution problem.
• At the same time strict legislative
measure to curb excessive emissions can
also be adopted.
What are the steps taken to control
vehicular pollution? By CPCB
• The following steps are taken:
• Establishment of Ambient Air Quality
Monitoring throughout India
• Notification of Ambient Air Quality
Standards under Environment (Protection)
• Notification of vehicular emission norms for year
1990-91,1996, 1998, 2000, 2001
• Improving fuel quality by phasing out lead from
gasoline, reducing diesel sulphur, reducing
gasoline benzene, and etc.
• Introduction of alternate fuelled vehicles like
• Improvement of public transport system.
• Phasing out of grossly polluting commercial
• Public awareness & campaigns.
• In the Constitution of India it is clearly
stated that it is the duty of the state to
‘protect and improve the environment
and to safeguard the forests and
wildlife of the country’.
• It imposes a duty on every citizen ‘to
protect and improve the natural
environment including forests, lakes,
rivers, and wildlife’.
What are the laws enforced by of the
Pollution Control Boards ? for
The Central and State Pollution Control Boards were set up
enforcement of the Water (Prevention & Control of Pollution) Act,
1974. Over the years, the Boards have been assigned additional
responsibilities which include the following :
Water (Prevention & Control of Pollution) Cess Act, 1977.
Air (Prevention & Control of Pollution) Act, 1981
Environment (Protection) Act, 1986 and Rules made thereunder
Hazardous Waste (Management & Handling) Rules1989.
Manufacture, storage and Import of Hazardous Chemicals Rules, 1989
Bio-medical Waste (Management & Handling) Rules, 1998
Municipal Solid Waste (Management & Handling) Rules, 2000.
Plastics wastes Rules, 1999 o Coastal Regulation Zone Rules, 1991
Public Liability Insurance Act, 1991
• Water act was introduced in 1974.
• Under above act aspects of air pollution
were not covered.
• Therefore The Air (Prevention and
control) pollution act, 1981 was
• Air pollution means any solid, liquid or
gaseous substance present in the atmosphere in
such concentration as may be or tend to be
injurious to human beings or living
organisms/creatures or plants or property or
Constitution of boards
• A state board under the act consists of following
17 members – all nominated by the state
1. A full time or part time chairman
2. Five official members to represent the government
3. Five persons representing the local authority
4. Three non official members from NGOs
5. Two persons representing companies/corporations
owned or managed by the state government
6. A full time member secretary
• Functions of Central Pollution Control
• Advise the Central Government on matters relating to
• Coordinate the activities of the State Boards;
• Provide Technical assistance to the State Boards, carry out
and sponsor investigations and research relating to control
• Plan and organize training of personnel;
• Collect, compile and publish technical and statistical data,
prepare manuals and code of conduct.
• To lay down standards;
• To plan nation wide programme for pollution control.
• Functions of the State Pollution
• To advise the State Government on matter relating
to pollution and on siting of industries
• To plan programme for pollution control;
• To collect and disseminate information;
• To carry our inspection;
• To lay down effluent and emission standards;
• To issue consent to industries and other activities for
compliance of prescribed emission and effluent
Penalties and procedures
• A person found guilty under this act may get
imprisonment not less than 1.5 yrs but which
may be extended up to 6 yrs and additional
fine up to Rs. 5000/- for every day during
which failure continues.
• If offence is committed by a company then
person responsible for conduct of company
will be held responsible and held guilty
Q1. Write short notes on
1. The Air (Prevention and control of pollution) Act,
1981 (Dec 2009, 6 marks)
2. Pollution due to automobiles. (May 2009,Dec 2009,
3. Control of automobile exhaust emissions. (Dec
2010,Dec 2010(old), 6 marks)
4. Air pollution control act (Nov 2008, May 2009,
Dec 2010, 6 marks) (Ans – Introduction, definition of
AP, constitution of boards, functions and penalties)