Air Pollution and Control Engineering

UNIT I - INTRODUCTION
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

Unit 1
Introduction
Syllabus
Structure and Composition of atmosphere – Definition, Scope and Scales of air pollution –
Source and classification of air pollutants and their effects on human health, vegetation
,animals, property, aesthetic value and visibility – Ambient air quality and Emission
standards.
Introduction
Earth is a unique planet because the life is found only on this planet. The air has a special
place among the conditions necessary for life. The air is a mixture of several gases. The air
encompasses the earth from all sides. The air surrounding the earth is called atmosphere. The
atmosphere is the integral part of the earth. Atmosphere protects the earth from harmful UV
rays and maintains suitable temperature of life.
The air is essential for the survival of all the forms of life on earth. One cannot imagine a life
in the absence of air. The atmosphere is a large protective cover. Besides many gases, water
vapor and dust particles are also found in atmosphere.
1. Structure and composition of atmosphere
The Earth’s Atmosphere:-
*Provides essential oxygen
*Provides medium for sound
*Shields solar radiation
*has been neglected
Earth’s great sphere are
1) Lithosphere
ii) Hydrosphere
iii) Biosphere
iv) Atmosphere
1) Lithosphere
The Lithosphere contains:
*All of the cold, hard solid land of the planets crust (surface)
*the semisolid land underneath the crust.
*the liquid land near the center of the planet.
ii) Hydrosphere
The Hydrosphere contains:-
*all the solid, liquid and gaseous water of the plane.
iii) Biosphere:
The Biosphere contains:
*all the planet’s living things
*all the microorganisms, plants and animals of earth.
iv) Atmosphere
The atmosphere contains:
*all the air in Earth’s system
Fig. Shows the earth spheres
1.1 Structure of atmosphere
*The atmosphere is an integral part of the earth.
*It surrounds the earth from all sides
*Generally it extends up to about 1600 km from the earth’s surface.
*The atmosphere can be divided into 5 layers according to the temperature and density.
The five layers are:
i)Troposphere ii) Stratosphere iii) Mesosphere iv) Ionosphere V) Exosphere
Fig.Shows the structure of atmosphere
i)Troposphere
*Lowest layer of the atmosphere
*The height of this layer is
→ 18 kms on the equator and
→ 8 kms on the poles
* The main reason of higher height at the equator is due to presence of hot convection
currents that push the gases upward.
*Important layer of the layer because
→All kinds of weather changes takes place only in this layer.
→Of these changes, development of living world take place on the earth.
→Air never remains static
→This layer is called changing sphere or Troposphere
*The environmental temperature decreases with increasing height of atmosphere.
→ It decreases at the rate of 10 C at the height of 165 m.
→This is called normal lapse rate
* The upper limit of troposphere is called Tropopause.
→ Transitional Zone
→ Troposphere and Troposphere Zone characteristics are found.
ii) Stratosphere
*This layer is above the troposphere
*This layer is spread about the height of 50 km from the earth’s surface. Its average extent 40
kms.
*The temperature remains same up to the height of 20 km and increases slowly with the
Increase in height.
*This temperature rise is due to the presence of ozone gas in the upper part of this layer.
*Weather related incidents do not take place in this layer. The air blows horizontally here.
*This layer is ideal for flying of aircrafts.
iii) Mesosphere:
*3rd layer of the atmosphere
* This layer spreads up to the height of 80 km from the earth’s surface and its extent is
30km.
* Temperature goes on increasing and drops to -1000 C
*Meteors or falling stars occur in this layer.
Fig: Structure of atmosphere
iv) Ionosphere:
*4th layer of the atmosphere above the mesosphere
*This layer spreads up to height of 400 kms from the surface of the earth. The width of this
layer is about 300 kms.
*Temperature increases with increasing height
*In this sphere, electrically charged currents flows in the air.
→Radio waves are reflected back on the earth from this sphere.
→Hence, radio broadcasting has become possible.
V) Exosphere:
*Last layer of the atmosphere located above Ionosphere
*This layer extends to beyond 400 km above the earth.
*Gases are very sparse due to lack of gravitational force
*Hence, the density of air is very less here.
1.2 Composition of Atmosphere
*The atmosphere is made up of different types of gases, water vapour and dust particles.
*The composition of the atmosphere is not static. It changes according to the time and place.
A. Gases of the atmosphere
*Main Gases:
1.Nitrogen – 78.1%
2.Oxygen – 20.9 % Total 99 %
*Secondary gas
1.Argon 0.9
2.CO2 0.03
3.Hydrogen 0.01
4.Neon 0.0018
5.Helium 0.0005
6.Ozone 0.00006
Fig Composition of Atmosphere

*Ozone Gas
*The amount of Ozone gas in the atmosphere is very little.
*It is limited to the ozone layer but very important.
*It protects the living beings by absorbing UV rays of the Sun.
* No Ozone gas – No existence of living beings and plants.
B.WaterVapour
*Gaseous form of water present in the atmosphere is called water vapour.
*Maximum amount of water vapour in the atmosphere is up to 4 %.
*Hot- wet regions – Max amount of water vapour and
*Deep region – least amount of water vapour.
*Amount of water vapourloses with increasing attitude.
*Water vapour reaches in the atmosphere through evaporation and transpiration.
*Evaporation takes place in the ocean,seas, rivers, ponds and lakes.
*Transpiration takes place from plants, trees and living beings.
C. Dust Particles:
*These are found in the lower layers of the atmosphere.
*These particles are found in the form of sand, smoke and oceanic salt.
*Sand particle have important place in the atmosphere.
*Dust particle helps in the
- Condensation of water vapour. During condensation, water vapour get condensed in the
form of droplets around these dust particles.
*Due to this process, clouds are formed and precipitation is possible.
Importance of the Atmosphere
i) Oxygen is very important for the living beings.
ii) Co2 is useful for the plants.
iii) Dust particles present in the atmosphere create suitable conditions for
precipitation.
iv) The amount of water vapour in the atmosphere goes on changing and affects the
plants and living beings directly.
v) Ozone protects all kinds of life on earth from harmful UV rays of the Sun.
2. Definition, scope and scales of Air pollution
2.1 Definition:
Air pollution is defined as “the presence of any solids, liquid or gaseous matter present in the
atmosphere in such concentrations that may or tend to be injurious to human beings or other
living creatures, plants and vegetation.”
IS – 4167(1966)– Indian Standards Institution.
“ Air pollution is the presence in ambient atmosphere of substances, generally resulting
from the activity of man, in sufficient concentration, present for a sufficient time and
under circumstances which interface significantly with the comfort, health or welfare of
persons or with the full or enjoyment of property.
2.2 Scope of Air pollution
*air pollution is a very serious problem and without taking appropriate sreps, it will
become worse.
Air pollution damages the environment
→ Trees, lakes and animals
*Air pollution has thinned the ozone layer
→This causes change in the environment.
*Air pollution damages property
→Building and structure, monuments and statues.
*Air pollution can cause haze
→Reducing visibility in cities and sometimes interfering with aviation.
*Air pollution affects human health.
→Breathing difficulty, birth defects, brain and nerve damage, long term injury to the lungs.
→Accidental releases can cause serious injury or even death.
Example
*Delhi – most polluted megacities of the world – offers a first-hand choice to study air
pollution problem.
*City accounts for 8 % of the registered motor vehicles in India, more than 3 other
metropolitan cities.
*A report published by Government of Delhi, found a higher percentage of certified death
due to disease of respiratory and circulatory system both of which are directly linked with air
pollution, for the period 2006-2014.
2.3 Scales of Air Pollution
Air pollution problems may occur on these scales:
i)Micro Scale
ii)Meso scale and
iii)Macro scale
i)Micro Scale
*Problems range from covering less than a centimeter to those the size of a house or slightly
larger.
*few meters to 100 ‘s of meter.
ii)Mesoscale
*Range – few hectares up to the size of a city or country
ie) local to regional.
iii)Macroscale
*Problems extend from countries to states, nations and in the broadest sense, the globe.
Ie) Regional to continental scale
Figure: Schematic diagram showing processes flow and scale within an urban
3.Sources and classification of air pollutants
Air Pollutants:
The solid, liquid or gaseous substances which causes air pollution is called air pollutants.
3.1 Classification of Air pollutants
Air pollutants are classified as:
i)Primary pollutant
ii)Secondary Pollutant
i)Primary Pollutant
The pollutant emitted directly from the sources, either from natural events (like dust storms
or volcanoes) or by human activities are called primary pollutant.
ii)Secondary pollutant
*Not emitted directly the primary pollutant react with one another, (water vapour or air) to
form a new pollutant is called secondary pollutant.
Another broad classes of Air pollutant are
i)Gaseous Air pollutants
→Pollutants in gaseous form
ii) Particulates
→Pollutants as particles.
i)Gaseous Air Pollutants:
*Includes sulfur Dioxide (SO2), Nitrogen Oxides (NOx), Ozone (O3), Carbon Monoxide
(CO), Volatile Organic Compounds (VOC), Hydrogen Sulphide (HF) and various gaseous
forms of metals.
*These pollutants are emitted from large stationary sources such as fossil fuel fired power
plants, industrial boilers, petroleum refineries, they are corrosive to various materials which
causes damage to cultural resources can causes injury to ecosystems and organisms,
aggravate respiratory diseases and reduce visibility.
ii)Particulates
*Come in both large and small or “fine” solid forms.
*Large particulates include substance such as dust, asbestos fibers and lead.
*Fine particulates include sulfates (SO4) nitrates (NO3)
*Important sources are:
Power plants, smelters, mining operations and automobiles.
*Asbestos and lead affect organisms
*Sulfates and nitrates contributes to acid rain and cause reduction in visibility.
*Particulate matter turn refers to mixture of solid particles and liquid droplets found in air.
Toxic Air Pollutant:
*Class of chemicals which causes health problems in a significant way.
*Sources are power plants, industries, pesticide application and contaminated wind blown
dust.
*Mercury – persistent toxic
Pollutant – particular concern
→because of global mobility
→accumulates in food chain
Primary and secondary pollutants:
*Primary – emitted directly into the air from pollution sources.
*Secondary – formed when air pollutants undergo chemical changes in the atmosphere.
*Ozone is an example of a secondary pollutant.
→Formed when Nitrogen oxides (NOx) and volatile organic compounds (VOC’ s) are mixed
and warmed by sunlight.
→Ozone (O3) is a major component of what is referred to as smog.
*Ozone present in the stratosphere is a beneficial one that helps protecting the earth from
harmful UV light from the sun.
3.2 Sources of Air Pollution:
Sources of Air pollution are:
i)Stationery and area sources
ii)Mobile sources
iii)Agricultural sources
ivI) Natural sources
i) Stationery and area sources
*Stationery source- refers to an emission does not move is known as point source
These sources include factories, power plants, dry cleaners and degreasing operations.
Area source-describes small sources of air pollution located together. whose,
→Individual emissions may be below the thresholds of concern.
→But collective emissions can be significant.
*Eg. Residential woos burners
*Area sources can also be the thought of as non- point source. Eg.
→Constitution of housing developments
→dry lakebuds
→land fills
ii)Mobile Sources:
*Refers to a source that is capable of moving under its own power.
*In general, “on – road” transportation-
Includes vehicles, cars, sport utility vehicles and buses.
*”Off board” or non – road category
Includes farm and construction equipment, boats, planes and trains.
iii)Agricultural sources:
*Are those, that raise animals and grow crops, can generate gas emission and particulate
matter.
*Eg.Animals confined to a restricted area (rather than field grazing) produce large amount of
manure.
*Manure emits various gases, particularly ammonia into air.
*This ammonia can be from manure storage areas or land after manure is applied.
*In crop production, the misapplication of fertilizers, herbicides and pesticides, can result in
drift of these materials and harm may be caused.
iv)Natural sources:
*Although industrialization and the use of motor vehicles are most significant contributors of
air pollution, there are important “ natural sources” of “pollution” as well.
*Wild land fires, dust storms and volcanic activity contributes to pollution.
*Natural “ air pollution is not caused by people or other activities.
Eg:
*erupting volcano emits particulate matter and gases.
*plants and tree naturally emit VOC’s which are oxidized and form aerosols that can cause
natural blue haze.
*Dust storms can create large amounts of particulate matter.
*Wild animals in their natural habitat are also considered as natural source of pollution.
*The national park service recognizes that each of these sources emits gases and particulate
matter into the atmosphere, but regarded as constituents from natural process.

4.Effects of Air Pollution on Human health, Vegetation, Animals, Property, Aesthetic

value and Visibility.
4.1 Human Health
*Irritate respiratory tract
*Irritate eyes, nose and throat
*Lead particles cause lead poisoning
*Cadmiums particles – Cardio vascular diseases, kidney and liver damage
*Nicks- particles – respiratory damage.
* Mercury – Central Nervous System Kidney and brain
*Radioactive Substances – affect future generation.
The effect of air pollutants on human health are difficult to assess. This is not because of the
effects are small, but because they are slow and get usually complicated by interaction of
the other factors such as overcrowding, occupation, habits and presence of more than
one pollutant at a time in the air. Further, some groups within the population may be
more sensitive to air pollution, particularly very young, very old, and those already
suffer from respiratory or other diseases, or exposed to other toxic materials. Children
are usually more prone because they breathe relatively higher quantity of air per unit
body weight than adults, and also have far fewer air sacs or alveoli in the lungs where
oxygen exchange takes placeof air pollution on human health have been concentrated
mainly on the following
A. The respiratory system
B. The eye
C. Chronic bronchitis
D Lung cancer
E Other respiratory diseases

A. The respiratory system:

The overall function of respiratory system is to bring the air into close contact with the
largenumber of blood capillaries, so as to facilitate the diffusion of atmospheric oxygen into
blood, and carbon dioxide out from the impure blood. It has been reported that the lower
respiratory tract is more efficient in removal of the particles in range of a micron. The
particles less than 10 microns may frequently enter into the alveolar sacs. However, there are
certain mechanisms by which these particles are removed from the alveolar sacs, but it is the
continuous exposure to high concentrations that overloads these removal mechanisms
leading to higher concentrations of deposited material in the lungs.

B. The eye:
The pollutants both gaseous and particulates, contact the external coat of the eye and the
internal mucous lining eyelid causing irritation. Physical damage to eyes may also result due
to excessive rubbing of the irritated eyes.

C. Chronic bronchitis:
It is characterized by a persistent production of cough. The breathing is hampered by
bronchial congestion and fluid often leading to the production of a bubbling sound as the air
passes through the fluid. The condition usually worsens in cold and damp weather.

D. Lung cancer:
Lung cancer is by far the common type of cancers induced by air pollution. When the
carcinoma of lung breaks after enlargement, it spreads throughout the body, moving
rapidly through lymphatic system and blood stream to spread cancer to other parts of the
body. A number of carcinogenic compounds including benzo(a)pyrene present in the
atmosphere may be responsible for development of lung cancer.
E. Other respiratory diseases:
Some other diseases have also been found epidemiologically to relate with the air pollution.
• Bronchial asthma is the narrowing of respiratory passage causing difficulty in
breathing.
• Pulmonary edema is a condition where excess fluid is accumulated in lungs.
• Pulmonary fibrosis is toughening of the lung tissues.
• Pneumoconiosis is inflammation of lung tissues caused by retention of foreign
particles.

Effects of air pollutants on plants:

Though most gaseous pollutants are actively metabolized by plants, yet many species are
susceptible to damage at even low concentrations of pollutants. For most pollutants plants
have been reported to be susceptible even to the concentrations that do not make any impact
on animals. Not all the plants are sensitive to air pollution. Some plants can resist fairly high
levels of pollution and can be employed as indicators of air pollution.

A. Kinds of injury to the plants:

The injury to the plants can be attributable to the acute or chronic exposures of air
pollutants. The acute effects relate to short term exposures to high concentrations of the
pollutants. The chronic effects are the result of prolonged exposures to low concentrations as
usually the case under normal ambient atmospheric conditions.

The responses of plants to air pollutants can be manifested in the following forms
1. Visible injury 2. Invisible injury

1 Visible Injury:
The visible injury generally occurs in the following forms
• Necrosis: Death and collapse of the cells causes lose water leaving a discolored dead
area in the green tissue.
• Chlorosis: Loss or reduction of chlorophyll resulting in bleaching or fading of the leafs
green colour that makes the leaf appears to yellowish or pale green.
• Abscission: Dropping of leaves.
• Epinasty: Downward curvature of the leaf due to higher rate of growth on the upper
surface.

2. Invisible injury:
The inviable injury is result of the impairment of physiological and biochemical
reactions. The most severe effects can occur on photosynthesis, respiration, photorespiration,
nitrogen, metabolism, pigment synthesis, enzyme structures and stomatal responses.
The reduction in growth, yield and reproduction is a measure of physiological and
biochemical disturbances brought about by the pollutants in the plants.

Effects of air pollutants on animals:

The effect of air pollution on animals is mostly indirect, as it occurs after they eat
polluted plants or foliage. Fluorine, lead and arsenic are three main air pollutants that cause
harmful effects to livestock.
Fluorine:
Fluorine causes loss of weight, muscular weakness, diarrhea, wearing of teeth, and
even death. Fluorosis mainly affects the ruminants, particularly dairy cows.

Lead:
Lead poisoning is commonly observed in animals grazing near lead mines. It is
associated with loss of appetite, difficulty in breathing, diarrhea and paralysis.

Arsenic:
Arsenic toxicity in animals is associated with increased salivation, thirst, irregular
pulses, abnormal body temperature and paralysis. Chronic poisoning may result in anemia,
diarrhea, paralysis and even death.

Effects of air pollutants on structures:

Air pollution has been recognized long back as a source of damage to the buildings,
monuments and other non-living materials leading to irreparable physical and economic loss.
The process of the physical deterioration has been greatly accelerated after the setting of
industrial revolution resulting into rise of the levels of air pollution.
Air pollution leads to widespread effects on physical structures mainly by way of
corrosion of metallic surfaces, soiling and erosion of buildings and historical monuments, and
damage to surface to coatings, paints, fabrics, textiles, plastics and other materials of
commerce. The common air pollutants responsible for this damage can include acid mists,
Sulphur dioxide, hydrogen sulphide, oxidants like ozone and particulates of diverse nature.
The best example is the case study of old monument in India (TajMahal).

Effects on Visibility
Any air traveller in United state is familiar with the permanent haze that exists over large
urban areas. The visibility reduction within this haze results from the scattering of light off
very fine particles 0.3 μm to 0.6 μm in diameter
Effects on Physical Features of atmosphere:
Effects on Physical Features of atmosphere are nothing but global effects of air pollution.
They are as follows:
A. Effect on visibility
B. Effect on atmospheric constituents
C. Green-house effect
D. Ozone layer depletion
E. Acid rain
F. Global warming

A. Effects on visibility: Fog and photochemical smog reduce the visibility considerably.
B. Effects on atmospheric constituent: Carbon dioxide CO2 is considered as a factor
responsible for rise in ambient temperature.
C. Green-house effect:
Cause: Gases like CO2, nitrogen oxide, ozone and chemicals likechlorofluorocarbon (CFC)
are responsible for green house effect. Carbon dioxide CO2 is the chief gas responsible
for the Green-house effect.
Effect: It causes appreciable rise in temperature of earths surface.
Remedy: Green house effect can be tackled by reducing the rate at which the fossil fuels like
coal are burnt.
D. Ozone layer depletion:
Cause: This ozone layer acts as an umbrella against the harmful ultraviolet radiation reaching
the earth. When chemical pollutants such as chlorofluorocarbon (CFC) emitted from
refrigeration and other industrial operations, nitrous oxide pollute the atmosphere and
some of the ozone is broken down and it results in decrease of ozone concentration in the
atmosphere. In consequence, more ultraviolet radiation reaches the earth.
Effects:
Damage of immune system,
Disturbance in ecosystem
Effect on crop yield
Increase of skin cancer and eye ailments
Shorter life of paints and plastics

Remedy: For protecting the ozone layer, the emission of chlorofluorocarbon (CFC) should
be restricted.

E. Acid rain:
The rain water is slightly acidic. The acidity level increases with SO2, NO2 etc., The
acidity in rain water is caused due to the formation of secondary pollutants such as sulphuric
acid (H2SO4), nitric acid (HNO3) and hydrochloric acid (HCl) due to the reaction of water
vapours with these gases.
It has been specified that when the pH of the rain water is less than or equal to 5 the rain
is termed as acid rain. 2/3 of acid rains is due to SO2, which is produced mainly by the
burning of coal and oil in industries . The SO2 pollutant leads to H2SO4 acidity. Another
primary pollutant responsible for 1/3 of acid rains is NOxwhich is produced mainly by the
automobile emissions. The NOxpollutant leads to HNO3 acidity. Acidic rains damage forests,
crops, buildings, monuments (eg: TajMahal monument).

F. Global warming:
Global warming is considered to be the outcome of the air pollution caused by the man-made
sources. The global warming may lead to burning of crops and may also cause forest fires.

PollutiontoProperty
In addition to damaging the environment and human health, air pollution can harm
buildings, monuments, outdoor statues, andother such structures. The chemicals in air
pollution eat away at materials such as sandstone, limestone, mortar, and different metals.
Acid rain dissolves stone and can create cracks in buildings.Repairing this damage,
particularly to historic structures, can be very expensive.

TheNationalCenterforPreservationTechnology&Trainingstudies the environmental

effects of pollution on property and works to restore and protect historic structures and
monuments.Homeowners also pay a price for air pollution. Acid rain can dissolve paint and
eat away at aluminum siding, while dirt particles in the air stick to a house and ruin its
appearance.
5.Ambient Air Quality and Emission Standards
If the emission standard philosophy,is “cleanest Possible air” the air Quality standard
philosophy is “Zero-damage”.

5.1 Ambient Air Quality Standards

Ambient air quality refers to the condition or quality of air surrounding us in the outdoors.

Ambient Air Quality Standards in INDIA

The Air(Prevention and Control of pollution)Act 1981 was enacted by the Central
Government with the objective of arresting the deteriozation of air quality.The Act describes
the main functions as follows:
(i) To advice the Central Government concerning the improvement of the air quality
and the prevention control and abatement of air pollution.
(ii) To plan and cause to be executed a nation-wide programme for the prevention
control and abatement of air pollution.
(iii) To provide technical assistance and guidance to the state pollution control board.
(iv) To carry out and sponsors investigation and reasearches related to prevention and
control of air pollution.
(v) To collect,compile and publish technical and statistical data related to air
pollution.
(vi) To lay down annual standards for the air quality.
 India has set Air Quality standards in 1994 later revised on 14th Oct,1998.Fqurther
Nov-2009 standards further lowered the maximum permissible limits for pollutants
and made the standards uniform across the nation.

International Standards
The 2005 World health Organization’s WHO Air quality guidelines offer global
guidance on thresholds and limits for 4 key air pollutants that cause health risks.
 PM(Particulates Matter)
 Ozone O3
 NO2
 SO2
Many countries have their own Ambient Air Quality Standards Prescribed for
their territories.
 US-The clean Air Act requires Environment Protection Agency(EPA) to set National
Ambient Air Quality Standards(NAAQS).
 Two types of Ambient Air Quality standards in the clean Air Act.
(i) Primary Standards
(ii) Secondary Standarads
 Primary Standards:Provide public health population including sensitive population
like children and the elderly.
 Secondary Standards:Provide public welfare protection against to
animals,crops,vegetations and buildings.
  NAAQS has been set for six pollutants in the US namely,
CO,Pb,NO2, O3 ,PM and SO2
 European Union-developed legislations on air quality standards.
 The pollutants for which the standards are:PM,SO2
,Pb,CO,O3,Ni,Cadmium(Cd),Arsenic(As) and polycyclic Aromatic Hydrocarbons.

5.2 Emission Standards

Emission Standards are the “legal requirements govering air pollutants released into the
atmosphere”.
Emission standards,”set the quantitative limits on the permissible amount of specific air
pollutants that may released from specific sources over specific the frames”.
They are generally developed to achieve “Cleanest air possible
Emission is the term used to describe “ the gases and particles which are put into the air
or emitted by various sources

Federal Regulations-Pollution Sources

(i) Large gasoline tank requires

Stage I Vapour Recovery-> Requires station’s underground tanks and trucks to fill the
connected in a way to minimize emission due to fuel transfer.
 Regulation describes the equipm
 Operation and maintenance technically
(ii) Open burning of garbage and agricultural waste is prohibited.
->Open burning generates more air pollutants per waste.
-> Recycling,closed incineration or composing.
-> By forbidding open burning,we force waste dispose to use
better technology
(iii) Visible Emission from stacks and vents particularly from chimney’s of coal
burning furnaces are emission to be limited.
->Regulation limiting these visible emissions are a from of emission standard.
(iv)Fuel Surfur Content and gasoline
Olefin content maxima and gasoline oxygen content minima are also emission standards
 Surfer in fuel enters the atmosphere as SO2
 Olefins causes photochemical Smog than other equivalent hydrocarbon.
 Autos using oxygen-gasoline exists less CO than other gasoline.
US-Air pollution law has 2 Sections “Pure” Emission Standards.
->These are the Standards of Performance for (i) New Stationary Sources.
[NSPS –New Source Performance Standards]
(ii) National Emission Standards for Hazardous Air Pollutants[NESHAP].
 NESHAP- Covers pollutants that are believed to have no threshold.
NESHAP-Any exposure is likely to produce some harm.
Federal Standards of Performance for NSPS
(i) Coal –fired power plants-may not emit the following to atmosphere.
a..PM (particulate Matter)
b.SO2
c.NO2
(ii) Large incinerators shall not emit to the atmosphere gases.There are also limits of
a.Cadmium
b.Lead
c.Mercury
d.Acid gases
(iii) Portland Cement Plants-Shall not emit the following to atmosphere.
a.Gases from the kiln[eg.CO]
b.Gases from the clinker cooler
(iv) Nitric Acid Plants shall not emit
a.NO2 of Nitric Acid produced
(v) Sulphuric Acid Plants shall not emit
a.Sulphuric Acid
The above regulations limits the opacity of plumes from these plants as a control measure and
have a detailed descriptions of testing and monitoring requirements.
U.S Law –Emission Standards-“PURE” because emission rates permitted were determined
strictly on the basis of best technology.

Comparision of Air Pollution Control-Philosophies

Desirable Quality Emission Standard Air Quality Standard
Cost Effectiveness Very bad Good
Simplicity Excellent Poor
Enforcebility Excellent Fair
Flexibility Poor Fair
Evolutionary Ability Fair Fair