2. Pollution

ME-161
Introduction to Mechanical Engineering
LEVEL-1, TERM-I
Military Institute of Science & Technology
Department of Mechanical Engineering
Adib Bin Rashid
Capt
Instructor Class C
Mechanical Engineering Department

Environmental Pollution
Adib Bin Rashid
Capt
Instructor Class C

Introduction to Air Pollution
Adib Bin Rashid
Capt
Instructor Class C

Definition
o Air pollution refers to the contamination of the air,
irrespective of indoors or outside.
o A physical, biological or chemical alteration to the air in the
atmosphere can be termed as pollution. It occurs when any
harmful gases, dust, smoke enters into the atmosphere and
makes it difficult for plants, animals and humans to survive
as the air becomes dirty.

Types and Sources of Air Pollution
o Air Pollution
• Chemicals added to the atmosphere by natural
events or human activities in high enough
concentrations to be harmful.
o Two categories
• Primary Air Pollutant
• Harmful substance that is emitted directly into the
atmosphere
• Secondary Air Pollutant
• Harmful substance formed in the atmosphere when a
primary air pollutant reacts with substances normally
found in the atmosphere or with other air pollutants

Causes of Air pollution
1. Burning of Fossil Fuels:
 Sulfur dioxide emitted from the combustion of fossil fuels
like coal, petroleum and other factory combustibles is one
the major cause of air pollution.
 Pollution emitting from vehicles including trucks, jeeps,
cars, trains, airplanes cause immense amount of pollution.
 Carbon Monooxide caused by improper or incomplete
combustion and generally emitted from vehicles is another
major pollutant along with Nitrogen Oxides, that is
produced from both natural and man made processes.

2. Agricultural activities:
o Ammonia is a very common by product from
agriculture related activities and is one of the
most hazardous gases in the atmosphere.
o Use of insecticides, pesticides and fertilizers in
agricultural activities has grown quite a lot.
They emit harmful chemicals into the air and
can also cause water pollution.

3. Exhaust from factories and industries:
o Manufacturing industries release large amount of
carbon monoxide, hydrocarbons, organic
compounds, and chemicals into the air thereby
depleting the quality of air.
o Manufacturing industries can be found at every
corner of the earth and there is no area that has
not been affected by it.
o Petroleum refineries also release hydrocarbons
and various other chemicals that pollute the air
and also cause land pollution.

4. Mining operations:
o Mining is a process where in minerals below the
earth are extracted using large equipments.
o During the process dust and chemicals are
released in the air causing massive air pollution.
This is one of the reason which is responsible
for the deteriorating health conditions of workers
and nearby residents.

5. Indoor air pollution:
o Household cleaning products, painting supplies emit
toxic chemicals in the air and cause air pollution.
o Suspended particulate matter popular by its acronym
SPM, is another cause of pollution. Referring to the
particles afloat in the air, SPM is usually caused by
dust, combustion etc.

Effects of Air pollution
1. Respiratory and heart problems:
o The effects of Air pollution are alarming. They are
known to create several respiratory and heart
conditions along with Cancer, among other threats
to the body.
o Several millions are known to have died due to
direct or indirect effects of Air pollution. Children in
areas exposed to air pollutants are said to
commonly suffer from pneumonia and asthma.

2. Global warming:
o Another direct effect is the immediate
alterations that the world is witnessing due to
Global warming.
o With increased temperatures world wide,
increase in sea levels and melting of ice from
colder regions and icebergs, displacement and
loss of habitat have already signaled an
impending disaster if actions for preservation
and normalization aren’t undertaken soon.

3. Acid Rain:
o Harmful gases like nitrogen oxides and sulfur
oxides are released into the atmosphere
during the burning of fossil fuels.
o When it rains, the water droplets combines
with these air pollutants, becomes acidic and
then falls on the ground in the form of acid
rain. Acid rain can cause great damage to
human, animals and crops.

4. Eutrophication:
o Eutrophication is a condition where high
amount of nitrogen present in some pollutants
gets developed on sea’s surface and turns
itself into algae and adversely affect fish,
plants and animal species.
o The green colored algae that is present on
lakes and ponds is due to presence of this
chemical only.

5. Effect on Wildlife:
o Just like humans, animals also face some
devastating affects of air pollution.
o Toxic chemicals present in the air can force
wildlife species to move to new place and
change their habitat. The toxic pollutants
deposit over the surface of the water and can
also affect sea animals.

6. Depletion of Ozone layer:
o Ozone exists in earth’s stratosphere and is
responsible for protecting humans from harmful
ultraviolet (UV) rays.
o Earth’s ozone layer is depleting due to the
presence of chlorofluorocarbons, hydro
chlorofluorocarbons in the atmosphere. As ozone
layer will go thin, it will emit harmful rays back on
earth and can cause skin and eye related
problems. UV rays also have the capability to
affect crops.

Solutions for Air Pollution
1. Use public mode of transportation: Encourage people
to use more and more public modes of transportation to
reduce pollution. Also, try to make use of car pooling. If
you and your colleagues come from the same locality and
have same timings you can explore this option to save
energy and money.
2. Conserve energy: Switch off fans and lights when you
are going out. Large amount of fossil fuels are burnt to
produce electricity. You can save the environment from
degradation by reducing the amount of fossil fuels to be
burned.

3. Understand the concept of Reduce, Reuse and
Recycle:
o Do not throw away items that are of no use to you. In-fact
reuse them for some other purpose. For e.g. you can use
old jars to store cereals or pulses.
4. Emphasis on clean energy resources:
o Clean energy technologies like solar, wind and geothermal
are on high these days. Governments of various countries
have been providing grants to consumers who are
interested in installing solar panels for their home. This will
go a long way to curb air pollution.

5. Use energy efficient devices:
o CFL lights consume less electricity as against their
counterparts. They live longer, consume less electricity,
lower electricity bills and also help you to reduce pollution
by consuming less energy.

Ozone Depletion in Stratosphere
o Ozone thinning/hole
• First identified in 1985
over Antarctica
o Caused by
• human-produced bromine
and chlorine containing
chemicals
• Ex: CFCs

o Ozone Protects earth from UV radiation
• Part of the electromagnetic spectrum with
wavelengths just shorter than visible light

o Hole over Antarctica requires two
conditions:
• Sunlight just returning to polar region
• Circumpolar vortex- a mass of cold air that
circulates around the southern polar region
• Isolates it from the warmer air in the rest of the
planet
o Polar stratospheric clouds form
• Enables Cl and Br to destroy ozone

Effects of Ozone Depletion
o Higher levels of UV-
radiation hitting the
earth
• Eye cataracts
• Skin cancer (right)
• Weakened immunity
o May disrupt
ecosystems
o May damage crops
and forests

Recovery of Ozone Layer
o Montreal Protocol (1987)
• Reduction of CFCs
• Started using HCFCs (greenhouse gas)
o Phase out of all ozone destroying chemicals
is underway globally
o Satellite pictures in 2000 indicated that
ozone layer was recovering
o Full recovery will not occur until 2050

Acid Deposition
o Sulfur dioxide and nitrogen dioxide emissions
react with water vapor in the atmosphere and
form acids that return to the surface as either
dry or wet deposition
o pH scale

Effects of Acid Deposition
o Declining Aquatic
Animal Populations
o Thin-shelled eggs
prevent bird
reproduction
• Because calcium is
unavailable in acidic soil
o Forest decline
• Ex: Black forest in
Germany (50% is
destroyed)

Acid Deposition and Forest Decline

Introduction to Water Pollution
Adib Bin Rashid
Capt
Instructor Class C

Water Pollution
Definition: Any chemical, biological and physical
change in water quality that has a harmful effect on
living organisms, Human & animals or makes it
unusable for agriculture is called Water pollution.

Causes of water pollution
1. Sewage:
 disposing of sewage waste is a major problem 40 percent of
the world's population) don't have proper sanitation (hygienic
toilet facilities); although there have been great improvements
in securing access to clean water, relatively little progress has
been made on improving global sanitation in the last decade.
Sewage disposal affects people's immediate environments
and leads to water-related illnesses such as diarrhea
 sewage contains all kinds of other chemicals, from the
pharmaceutical drugs people take to the paper, plastic, and
other wastes they flush down their toilets. When people are
sick with viruses, the sewage they produce carries those
viruses into the environment. It is possible to catch illnesses
such as hepatitis, typhoid, and cholera from river and sea
water.

2. Waste water
o Factories are point sources of water pollution, but quite a lot of water is
polluted by ordinary people from nonpoint sources; this is how ordinary
water becomes waste water in the first place.
o Virtually everyone pours chemicals of one sort or another down their drains
or toilets. Even detergents used in washing machines and dishwashers
eventually end up in our rivers and oceans. So do the pesticides we use on
our gardens. A lot of toxic pollution also enters waste water from highway
runoff. Highways are typically covered with a cocktail of toxic chemicals—
everything from spilled fuel and brake fluids to bits of worn tires.
o When it rains, these chemicals wash into drains and rivers.

3. Nutrients
 Chemical fertilizers used by farmers also add nutrients to the soil, which
drain into rivers and seas and add to the fertilizing effect of the sewage.
Together, sewage and fertilizers can cause a massive increase in the
growth of algae or plankton that overwhelms huge areas of oceans, lakes,
or rivers. This is known as a harmful algal bloom.
 It is harmful because it removes oxygen from the water that kills other
forms of life, leading to what is known as a dead zone. The Gulf of Mexico
has one of the world's most spectacular dead zones

4. Chemical waste
o Toxic pollution comes from heavy metals, such as lead,
cadmium, and mercury.
o Lead was once commonly used in gasoline (petrol), though
its use is now restricted in some countries. Mercury and
cadmium are still used in batteries .
o A highly toxic chemical called tributyltin (TBT) was used in
paints to protect boats from the ravaging effects of the
oceans. Ironically, however, TBT was gradually recognized
as a pollutant: boats painted with it were doing as much
damage to the oceans as the oceans were doing to the
boats.

5. Radioactive waste
o Radioactive pollution from nuclear power plants
6. Oil Spilling
o Only 12 percent of the oil that enters the oceans
comes from tanker accidents
o Over 70 percent of oil pollution at sea comes from
routine shipping and from the oil people pour down
drains on land

6. Plastics
 Plastic is one of the most common materials, used for making
virtually every kind of manufactured object from clothing to
automobile parts; plastic is light and floats easily so it can
travel enormous distances across the oceans; most plastics
are not biodegradable (they do not break down naturally in
the environment), which means that things like plastic bottle
tops can survive in the marine environment for a long time.
 Plastics are not toxic in quite the same way as poisonous
chemicals, they nevertheless present a major hazard to
seabirds, fish, and other marine creatures.

Effects of water Pollution
1. Death of aquatic (water) animals
The main problem caused by water pollution is that it kills life
that depends on these water bodies. Dead fish, crabs, birds
and sea gulls, dolphins, and many other animals often wind up
on beaches, killed by pollutants in their habitat (living
environment).
2. Disruption of food-chains
Pollution disrupts the natural food chain as well. Pollutants such
as lead and cadmium are eaten by tiny animals. Later, these
animals are consumed by fish and shellfish, and the food chain
continues to be disrupted at all higher levels.

Effects of water Pollution
3. Diseases
Eventually, humans are affected by this process as well. People
can get diseases such as hepatitis by eating seafood that has
been poisoned. In many poor nations, there is always outbreak
of cholera and diseases as a result of poor drinking water
treatment from contaminated waters.
4. Destruction of ecosystems
Ecosystem (the interaction of living things in a place,
depending on each other for life) can be severely changed or
destroyed by water pollution. Many areas are now being
affected by careless human pollution, and this pollution is
coming back to hurt humans in many ways.

Prevention of water pollution.
o Never throw rubbish away anyhow. Always look for the correct waste
bin. If there is none around, please take it home and put it in your trash
can. This includes places like the beach, riverside and water bodies.
o Use water wisely. Do not keep the tap running when not in use. Also,
you can reduce the amount of water you use in washing and bathing. If
we all do this, we can significantly prevent water shortages and reduce
the amount of dirty water that needs treatment.
o Do not throw chemicals, oils, paints and medicines down the sink drain,
or the toilet. In many cities, your local environment office can help with
the disposal of medicines and chemicals. Check with your local
authorities if there is a chemical disposal plan for local residents.

Prevention of water pollution.
o Buy more environmentally safe cleaning liquids for use at
home and other public places. They are less dangerous to
the environment.
o If you use chemicals and pesticides for your gardens and
farms, be mindful not to overuse pesticides and fertilizers.
This will reduce runoffs of the chemical into nearby water
sources. Start looking at options of composting and using
organic manure instead.
If you live close to a water body, try to plant lots of trees and
flowers around your home, so that when it rains, chemicals
from your home does not easily drain into the water.

2. Pollution

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