Unit iv ES F. Y. BTECH

SRES’S Sanjivani College of Engineering, Kopargaon
(An Autonomous Institute)
Environmental Science (Audit Course)
Prepared By: Dr. M.V. Jadhav
Prof. U.T. Kulkarni
1
UNIT- IV
AIR & NOISE POLLUTION
4.1 Air Pollution
Air pollution is the mixing of unwanted and harmful substances such as chemicals, dust,
auto emissions, suspended particles, gases among others in our atmosphere.
In other words, Air pollution occurs when harmful or excessive quantities of substances
including gases (such as carbon dioxide, carbon monoxide, sulfur dioxide, nitrous
oxides, methane and chlorofluorocarbons), particulates (both organic and inorganic),
and biological molecules are introduced into Earth's atmosphere. It may cause diseases,
allergies and even death to humans; it may also cause harm to other living organisms such as
animals and food crops, and may damage the natural or built environment. Both human
activity and natural processes can generate air pollution.
4.1.1 Sources of Air Pollution
There are various locations, activities or factors which are responsible for releasing
pollutants into the atmosphere. These sources can be classified into two major categories.
A) Anthropogenic (man-made) sources
B) Natural sources
Anthropogenic (man-made) sources
 Stationary sources include smoke stacks of fossil fuel power stations , manufacturing facilities
(factories) and waste incinerators, as well as furnaces and other types of fuel-burning heating
devices.
 Mobile sources include motor vehicles, marine vessels, and aircraft.
 Controlled burn practices in agriculture and forest management.
 Fumes from paint, hair spray, varnish, aerosol sprays and other solvents.
 Waste deposition in landfills, which generate methane.
 Military resources, such as nuclear weapons, toxic gases, germ warfare and rocketry.

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 Fertilized farmland may be a major source of nitrogen oxides.
Natural sources
 Dust from natural sources, usually large areas of land with little vegetation or no vegetation
 Methane, emitted by the digestion of food by animals, for example cattle
 Radon gas from radioactive decay within the Earth's crust. Radon is a colorless, odorless,
naturally occurring, radioactive noble gas that is formed from the decay of radium.
 Smoke and carbon monoxide from wildfires.
 Vegetation, in some regions, emits environmentally significant amounts of Volatile organic
compounds (VOCs) on warmer days. These VOCs react with primary anthropogenic
pollutants—specifically, NOx, SO2, and anthropogenic organic carbon compounds — to
produce a seasonal haze of secondary pollutants
 Volcanic activity, which produces sulfur, chlorine, and ash particulates.
Indoor Air Pollution
Air pollution is usually thought of as smoke from large factories or exhaust from vehicles. But
there are many types of indoor air pollution as well.
Heating a house by burning substances such as kerosene, wood, and coal can contaminate the air
inside the house. Ash and smoke make breathing difficult, and they can stick to walls, food, and
clothing.
Naturally-occurring radon gas, a cancer-causing material, can also build up in homes. Radon is
released through the surface of the Earth. Inexpensive systems installed by professionals can reduce
radon levels.
4.1.2 Types of Air Pollutants
An air pollutant is a material in the air that can have adverse effects on humans and the
ecosystem. The substance can be solid particles, liquid droplets, or gases. A pollutant can be of
natural origin or man-made. Pollutants are classified as primary or secondary.

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Primary pollutants are usually produced by processes such as ash from a volcanic eruption.
Other examples include carbon monoxide gas from motor vehicle exhausts or sulfur
dioxide released from factories.
Secondary pollutants are not emitted directly. Rather, they form in the air when primary
pollutants react or interact. Ground level ozone is a prominent example of secondary pollutants.
Some pollutants may be both primary and secondary: they are both emitted directly and formed
from other primary pollutants.
1. Particulate matter (PM)
Particulate matter is a complex mixture of solids and liquids, including carbon, complex
organic chemicals, sulphates, nitrates, mineral dust, and water suspended in the air.
It varies in size. Some particles, such as dust, soot, dirt or smoke are large or dark enough to
be seen with the naked eye. But the most damaging particles are the smaller particles, known as
PM10and PM2.5. PM10refers to particles with a diameter that’s smaller than 10 microns (10µm)
– that’s 10 millionths of a metre. PM2.5 refers to particles with a diameter smaller than 2.5 microns,
and these are known as fine particles. The smallest fine particles, less than 0.1 micron in diameter,
are called ultra fine particles.

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Fig 1. Particulate Matter
Man-made particulate matter mainly comes from industrial processes, construction work,
emissions from diesel and petrol engines, friction from brakes and tyres, and dust from road
surfaces. Diesel engines tend to produce much more than equivalent petrol engines.
2. Nitrogen dioxide (NO2)
Nitrogen dioxide is a gas and is a major component of urban air pollution episodes.
Man-made sources of nitrogen oxides, including nitrogen dioxide, are vehicles, power stations
and heating. Diesel vehicles are major contributors in urban areas. Roadside levels are highest
where traffic is busiest.
Natural sources of particulate matter include volcanoes, sea spray, pollen and soil. It is also
formed in the atmosphere when gases such as nitrogen dioxide and sulphur dioxide are changed in
the air by chemical reactions.
3. Ozone (O3)
Ozone is a gas composed of three atoms of oxygen. In the upper level of the Earth’s atmosphere,
it absorbs harmful ultraviolet radiation.
Near the ground, ozone is made by a chemical reaction between the sun’s rays and organic
gases and oxides of nitrogen emitted by cars, power plants, chemical plants and other sources.
Levels of ozone tend to be highest in the spring and summer and lowest in the winter. Ozone
reaches its peak concentration during the afternoon. Levels are often higher in the country than in
towns. Ozone is a major component of summer air pollution episodes.
4. Sulphur dioxide (SO2)
Sulphur dioxide is a colourless gas, with a pungent, suffocating smell. It’s produced by burning
sulphur-containing fuels such as coal and oil. This includes, vehicles, power generation and heating.
Most sulphur dioxide comes from electric industries that burn fossil fuels, and also from petrol
refineries and cement manufacturing. It can be transported over long distances and contributes to
the formation of ozone.
4.1.3 Effects of Air Pollution

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Effects On Humans
People experience a wide range of health effects from being exposed to air pollution. Effects can
be broken down into short-term effects and long-term effects.
Short-term effects, which are temporary, include illnesses such as pneumonia or bronchitis. They
also include discomfort such as irritation to the nose, throat, eyes, or skin. Air pollution can also
cause headaches, dizziness, and nausea. Bad smells made by factories, garbage, or sewer systems
are considered air pollution, too. These odors are less serious but still unpleasant.
Long-term effects of air pollution can last for years or for an entire lifetime. They can even lead to
a person's death. Long-term health effects from air pollution include heart disease, lung cancer,
and respiratory diseases such as emphysema. Air pollution can also cause long-term damage to
people's nerves, brain, kidneys, liver, and other organs. Some scientists suspect air pollutants
cause birth defects. Nearly 2.5 million people die worldwide each year from the effects of outdoor
or indoor air pollution.
People react differently to different types of air pollution. Young children and older adults,
whose immune systems tend to be weaker, are often more sensitive to pollution. Conditions such
as asthma, heart disease, and lung disease can be made worse by exposure to air pollution. The
length of exposure and amount and type of pollutants are also factors.
Effects On The Environment
Like people, animals, and plants, entire ecosystems can suffer effects from air pollution. Haze, like
smog, is a visible type of air pollution that obscures shapes and colors. Hazy air pollution can even
muffle sounds.
Air pollution particles eventually fall back to Earth. Air pollution can directly contaminate the
surface of bodies of water and soil. This can kill crops or reduce their yield. It can kill young trees
and other plants.
Sulfur dioxide and nitrogen oxide particles in the air, can create acid rain when they mix with water
and oxygen in the atmosphere. These air pollutants come mostly from coal-fired power plants
and motor vehicles. When acid rain falls to Earth, it damages plants by changing soil
composition; degrades water quality in rivers, lakes and streams; damages crops; and can cause
buildings and monuments to decay.
Like humans, animals can suffer health effects from exposure to air pollution. Birth defects,
diseases, and lower reproductive rates have all been attributed to air pollution.

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Global Warming
Global warming is an environmental phenomenon caused by natural and anthropogenic air
pollution. It refers to rising air and ocean temperatures around the world. This temperature rise is
at least partially caused by an increase in the amount of greenhouse gases in the atmosphere.
Greenhouse gases trap heat energy in the Earths atmosphere. (Usually, more of Earths heat escapes
into space.)
Carbon dioxide is a greenhouse gas that has had the biggest effect on global warming. Carbon
dioxide is emitted into the atmosphere by burning fossil fuels (coal, gasoline, and natural gas).
Humans have come to rely on fossil fuels to power cars and planes, heat homes, and run factories.
Doing these things pollutes the air with carbon dioxide.
Other greenhouse gases emitted by natural and artificial sources also include methane, nitrous
oxide, and fluorinated gases. Methane is a major emission from coal plants and agricultural
processes. Nitrous oxide is a common emission from industrial factories, agriculture, and the
burning of fossil fuels in cars. Fluorinated gases, such as hydrofluorocarbons, are emitted by
industry. Fluorinated gases are often used instead of gases such as chlorofluorocarbons (CFCs).
CFCs have been outlawed in many places because they deplete the ozone layer.
Worldwide, many countries have taken steps to reduce or limit greenhouse gas emissions
to combat global warming. The Kyoto Protocol, first adopted in Kyoto, Japan, in 1997, is an
agreement between 183 countries that they will work to reduce their carbon dioxide emissions.
4.1.4 Prevention of Air Pollution
Industries release smoke and other harmful gases into the atmosphere. This causes the air
quality index in the surrounding areas to be very poor. A bad air quality index indicates that air is
not fit for breathing and can cause many unwanted problems. Therefore, the problem of air
pollution has to be tackled at the root level.
Devices like the electrostatic precipitator and scrubber help in removing particulate matter and
some harmful gases respectively. The use of electrostatic precipitator is one of the widely used
ones to remove the particulate matter that get suspended in the air.
This is mostly used in thermal power plants where the particulate matter concentration is high
in exhausts. This device has electrode wires that produce a corona to release electrons. When dust
particles are released, these electrons attach to the dust particles, thus giving them a negative charge.

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There are collecting plates that are grounded, which attract these charged dust particles. The dust
particulate matter is thus removed from the smoke coming out of exhausts in thermal power plants.
A scrubber is an apparatus that removes gases like Sulphur dioxide. In a scrubber, the exhaust
goes through a spray of water or lime. This water dissolves the gases and with the reactions of lime
and sulfur dioxide, precipitates are formed. Clean air then comes out, as it is now devoid of the
harmful gases.
Usage of unleaded petrol in automobiles is also recommended. To reduce the emissions of
poisonous gases like carbon monoxide and nitrogen dioxide, automobiles are also fitted with
catalytic converters.
Table 1. Ambient Air Quality Standards
4.2 Noise Pollution
Noise pollution, also known as environmental noise or sound pollution, is the propagation of
noise with harmful impact on the activity of human or animal life. The source of outdoor noise
worldwide is mainly caused by machines, transport, and propagation systems. Poor urban
planning may give rise to noise pollution, side-by-side industrial and residential buildings can

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result in noise pollution in the residential areas. Some of the main sources of noise in residential
areas include loud music, transportation (traffic, rail, airplanes, etc), lawn care
maintenance, construction, electrical generators, explosions, and people. Documented problems
associated with urban environment noise go back as far as ancient Rome. Noise is measured in
Decibel (dB). Noise pollution associated with household electricity generators is an emerging
environmental degradation in many developing nations. The average noise level of 97.60 dB
obtained exceeded the WHO value of 50 dB allowed for residential areas. Research suggests that
noise pollution is the highest in low-income and racial minority neighborhoods.
High noise levels can contribute to cardiovascular effects in humans and an increased
incidence of coronary artery disease. In animals, noise can increase the risk of death by altering
predator or prey detection and avoidance, interfere with reproduction and navigation, and
contribute to permanent hearing loss. While the elderly may have cardiac problems due to noise,
according to the World Health Organization, children are especially vulnerable to noise, and the
effects that noise has on children may be permanent. Noise poses a serious threat to a child’s
physical and psychological health, and may negatively interfere with a child's learning and
behavior.
4.2.1 Sources of Noise Pollution
Sources of Noise Pollution:
Major causes / sources of noise pollution are:
(i) Industrial Sources:
Progress in technology (industrialization) has resulted in creating noise pollution. Textile mills,
printing presses, engineering establishments and metal works etc. contribute heavily towards noise
pollution. In industrial cities like Kolkata, Ludhiana, Kanpur etc., often the industrial zones are not
separated from the residential zones of the city especially in the case of small scale industries.
These operate from workshops located on the ground floors of the residential areas and cause
annoyance, discomfort and irritation to the residents exposed to the noise that is inevitably
produced. The situation is much better in modern planned cities like Chandigarh where the
industrial area is kept away from the residential areas and both are separated from each other by a
sufficiently wide green belt.

Prof. U.T. Kulkarni
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(ii) Transport Vehicles:
Automobile revolution in urban centers has proved to be a big source of noise pollution.
Increasing traffic has given rise to traffic jams in congested areas where the repeated hooting of
horns by impatient drivers pierce the ears of all road users.
Noise from airplanes constitutes an increasing serious problem in big cities like Delhi &
Mumbai. Airport situated in the vicinity of population centres and the air planes pass over
residential areas. Heavy trucks, buses trains, jet-planes, motor-cycles, scooters, mopeds, jeeps—
the list of vehicles is endless but the outcome is same — noise pollution.
(iii) Household:
The household is an industry in itself and is a source of many indoor noises such as the banging
of doors, noise of playing children, crying of infants, moving of furniture, loud conversation of the
inhabitants etc. Besides these are the entertainment equipment in the house, namely the radio,
record-players and television sets. Domestic gadgets like the mixer-grinders, pressure cookers,
desert coolers, air- conditioners, exhaust fans, vacuum cleaners, sewing and washing machines are
all indoor sources of noise pollution.
(iv) Public Address System:
In India people need only the slightest of an excuse for using loud speakers. The reason may
be a religious function, birth, death, marriage, elections, demonstration, or just commercial
advertising. Public system, therefore, contributes in its own way towards noise pollution.
(v) Agricultural Machines:
Tractors, thrashers, harvesters, tube wells, powered tillers etc. have all made agriculture highly
mechanical but at the same time highly noisy. Noise level 90 dB to 98 dB due to running of farm
machines have been recorded in the state of Punjab.
(vi) Defence Equipment:
A lot of noise pollution is added to the atmosphere by artillery, tanks, launching of rockets,
explosions, exercising of military airplanes and shooting practices. Screams of jet engines and
sonic booms have a deafening impact on the ears and in extreme cases have been known to shatter
the window panes and old dilapidated buildings.

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(vii) Miscellaneous Sources:
The automobile repair shops, construction-works, blasting, bulldozing, stone crushing etc. are
other sources of noise pollution.
4.2.2 Effects of Noise Pollution
Noise is generally harmful and a serious health hazard. It has far-reaching consequences and
has many physical, physiological as well as psychological effects on human beings.
(i) Physical Effects:
The physical manifestation of noise pollution is the effect on hearing ability. Repeated
exposure to noise may result in temporary or permanent shifting of the hearing threshold of a person
depending upon the level and duration of exposure. The immediate and acute effect of noise
pollution is impairment of hearing (i.e. total deafness.)
Human ears have sensory cells for hearing. If these cells are subjected to repeated sounds of
high intensity before they have an opportunity to recover fully, they can become permanently
damaged leading to impairment of hearing. Besides the sensory cells, the delicate tympanic
membrane or the ear drum can also be permanently damaged by a sudden loud noise such as an
explosion.
(ii) Physiological Effects:
The physiological manifestations of noise pollution are several as mentioned below:
(a) Headache by dilating blood vessels of the brain.
(b) Increase in the rate of heart-beat.
(c) Narrowing of arteries.
(d) Fluctuations in the arterial blood pressure by increasing the level of cholesterol in the blood.
(e) Decrease in heart output.
(f) Pain in the heart.
(g) Digestive spasms through anxiety and dilation of the pupil of the eye, thereby causing eye-
strain.
(h) Impairment of night vision.

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(i) Decrease in the rate of colour perception.
(j) Lowering of concentration and affect on memory,
(k) Muscular strain and nervous breakdown.
Psychological Effect
The psychological manifestations of noise pollution are:
(a) Depression and fatigue which considerably reduces the efficiency of a person.
(b) Insomnia as a result of lack of undisturbed and refreshing sleep
(c) Straining of senses and annoyance as a result of slow but persistent noise from motorcycles,
alarm clocks, call bells, telephone rings etc.
(d) Affecting of psychomotor performance of a person by a sudden loud sound
(e) Emotional disturbance
For a talkative person, the most important effect of noise pollution would invariably be that
noise interferes with our conservation. So, noise is annoying and the annoyance depends on many
factors not merely the intensity of the sound but also repetition, because even a sound of small
intensity (e.g. dripping tap or clicking of clock) may become annoying, simply by repetition.
Table 2. Ambient Noise Quality Standards
4.3 Measures For Prevention/Control Of Noise Pollution
1. Considering the widespread ill-effects of noise pollution, measures need to be taken to control
them.

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2. Increasing noise pollution is very harmful for the health, efficiency and productivity of animals,
organisms, flora etc. as well as the adaptation and balance of the environment.
3. It has become necessary to control it and also to make people aware of this.
4. Factories, which mainly produce noise pollution, should be established far away from
settlements, forests, reservoirs and hilly areas.
5. Settlements should not be located at least within 20 kilometres from mining areas, and airports.
6. Explosives should be not used in mountainous, forest and mining areas.
7. With proper maintenance of vehicles, along with the restriction of high sound horns, the use of
advanced technology silencer should be used inevitably.
8. Use of horn in public places (hospital, teaching institutes etc.) should be banned.
9. The sound of musical instruments should be controlled to desirable limits
10. There should be control over noise generated from machine and equipment.
11. The use of sound absorber acoustic tiles should be encouraged in the construction of multi-
storeyed buildings.
12. In industrial, commercial and hospital buildings, adequate soundproof systems should be
installed.
13. Intensive plantation should be made in the entire building complex.
14. Planting green trees along the road side reduces the intensity of noise pollution.
15. Dense tree cover is very useful in the prevention of noise pollution. Such trees help in absorbing
high sound waves, as well as deflecting them into the atmosphere. Therefore, cities, highways,
industrial settlements should be fully lined with the green belt of trees.
16. Protective tools (ear plugs etc.) should be provided for workers.
17. Limits should be set on noise and control over noise pollution by legal provisions.
18. Adequate health education on pollution should be provided through government agencies and
voluntary institutions.

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Unit iv ES F. Y. BTECH

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