Transcript AIR POLLUTION

Definition of Air Pollution
Air pollution occurs when the air contains
gases, dust, fumes or odour in harmful
amounts. That is, amounts which could be
harmful to the health or comfort of humans
and animals or which could damage to
plants and materials.
The substances that cause air pollution are
called pollutants.
Air Pollution is the human introduction
into the atmosphere of chemicals,
particulates, or biological materials that
cause harm or discomfort to humans or
other living organisms, or damage the
environment.
Air pollution causes deaths and
respiratory disease.
Sources of Pollutants
The two main sources of pollutants in urban
areas are transportation (predominantly
automobiles) and fuel combustion in
stationary sources, including residential,
commercial, and industrial heating and
cooling and coal-burning power plants.
Motor vehicles produce high levels of
carbon monoxides (CO) and a major source
of hydrocarbons (HC) and
nitrogen oxides (NOx).
Whereas, fuel combustion in stationary
sources is the dominant source of
sulfur dioxide (SO2).
Carbon Dioxide - CO2
Carbon dioxide (CO2) is one of the major
pollutants in the atmosphere. Major sources
of CO2 are fossil fuels burning and
deforestation. CO2
a greenhouse gas
emitted from
combustion.
Carbon Monoxide -CO
Carbon monoxide is colourless, odourless,
non-irritating but very poisonous gas.
It is a product by incomplete combustion of
fuel such as natural gas, coal or wood.
Vehicular exhaust is a major source of
carbon monoxide.
N0X - nitric oxide (N0) and
nitrogen dioxide (N02)






Natural component of the Earth's atmosphere.
Important in the formation of both acid precipitation and
photochemical smog (ozone), and causes nitrogen
loading.
Comes from the burning of biomass and fossil fuels.
30 to 50 million tons per year from human activities, and
natural 10 to 20 million tons per year.
Average residence time in the atmosphere is days.
Has a role in reducing stratospheric ozone.
Sulfur Oxides - SOx
Sulfur oxides (SOx) especially sulfur dioxide
are emitted from burning of coal and oil.
At sufficiently high concentrations, sulfur
dioxide irritates the upper respiratory tract of
human beings because potential effect of
sulfur dioxide is to make breathing more
difficult by causing the finer air tubes of the
lung to constrict.
Chlorofluorocarbons (CFCs)
CFCs are lowering the average
concentration of ozone in the stratosphere.
 Spray cans, discarded or leaking
refrigeration and air conditioning
equipment, and the burning plastic foam
products release the CFCs into the
atmosphere. Depending on the type,
CFCs stay in the atmosphere from 22 to
111 years.

Smog
This smog is created by burning coal and
heavy oil that contain sulfur impurities in
power plants, industrial plants, etc...
The smog consists mostly of a mixture of
sulfur dioxide and fog. Suspended droplets of
sulfuric acid are formed from some of the
sulfur dioxide, and a variety of suspended
solid particles.
This smog is common during the winter in
cities such as London, Chicago, Pittsburgh.
When these cities burned large amounts of
coal and heavy oil without control of the
output, large-scale problems were witnessed.
In 1952 London, England, 4,000 people died
as a result of this form of fog. Today coal
and heavy oil are burned only in large
boilers and with reasonably good control or
tall smokestacks so that industrial smog is
less of a problem.
Smog can form in almost any climate
where industries or cities release large
amounts of air pollution.
Volatile Organic Compounds (VOC),
such as hydrocarbon fuel vapors and
solvents.
Toxic metals such as lead, cadmium and
copper.
Ammonia emitted from agricultural
processes.
Odors such as from garbage, sewage
and industrial processes.
Radioactive pollutants.
Secondary Pollutants:
Ground level ozone (O3) formed from
NOx and VOC.
Peroyacetyl (PAN) similarly formed from
NOx and VOC.
Indoor Air Pollution
Pollutions from power plants, cars, and
other transportation is a well-known
contributor to outdoor air pollution.
But indoor air pollution is often worse; it
can be up to 10 times worse for you than
the air outside.
Indoor pollution sources release chemicals,
micro chemicals, micro-organisms, and
organisms, and particulates into the air
 Inadequate ventilation to dilute the
pollutants.
 Inadequate filtration to remove micro microorganisms and particulates

Major Indoor Air Pollutants
IAQ for Offices and Public Places
Health Effects
Air pollution can affect our health in many
ways with both short-term and long-term
effects. Examples of short-term effects
include irritation to the eyes, nose and
throat, and upper respiratory infections such
as bronchitis and pneumonia.
Other symptoms can include
headaches, nausea,
and allergic reactions.
Long-term health effects can
include chronic respiratory disease,
lung cancer, heart disease, and even
damage to the brain, nerves, liver, or
kidneys. It is estimated that half a
million people die prematurely every
year in the United States as a result of
smoking cigarettes.
Environmental Impacts
Pollutants such as sulfur dioxide, nitrogen
oxides, ozone and peroxyacl nitrates
(PANs), cause direct damage to leaves of
crop plants and trees when they enter leaf
pores (stomates).
Trees play an important role in producing
oxygen from carbon dioxide.
Effects
Acid Rain
 Greenhouse Effect
 Climate Change
 Global Warming

With the destruction and burning of the rain
forests more and more CO2 is being
released into the atmosphere. Trees play an
important role in producing oxygen from
carbon dioxide. This process is called
photosynthesis which all plants go though
but some yield more and some less oxygen.
As long as no more wood is burnt than is
reproduced by the forests, no change in
atmospheric CO2 concentration will result.
Acid Rain
"Acid rain" is a broad term referring to a
mixture of wet and dry deposition (deposited
material) from the atmosphere containing
higher than normal amounts of nitric and
sulfuric acids. The precursors, or chemical
forerunners, of acid rain formation result
from both natural sources, such as
volcanoes and decaying vegetation, and
man-made sources, primarily emissions of
sulfur dioxide (SO2) and nitrogen oxides
(NOx) resulting from fossil fuel combustion.
Wet Deposition
Wet deposition refers to acidic rain, fog, and
snow. If the acid chemicals in the air are
blown into areas where the weather is wet,
the acids can fall to the ground in the form of
rain, snow, fog, or mist. As this acidic water
flows over and through the ground, it affects
a variety of plants and animals. The strength
of the effects depends on several factors,
including how acidic the water is; the
chemistry and buffering capacity of the soils
involved; and the types of fish, trees, and
Dry Deposition
In areas where the weather is dry, the acid
chemicals may become incorporated into
dust or smoke and fall to the ground through
dry deposition, sticking to the ground,
buildings, homes, cars, and trees. Dry
deposited gases and particles can be
washed from these surfaces by rainstorms,
leading to increased runoff. This runoff water
makes the resulting mixture more acidic.
About half of the acidity in the atmosphere
falls back to earth through dry deposition
Greenhouse Effect
The greenhouse effect is unquestionably
real and helps to regulate the temperature of
our planet. It is essential for life on Earth and
is one of Earth's natural processes. It is the
result of heat absorption by certain gases in
the atmosphere (called greenhouse gases
because they effectively 'trap' heat in the
lower atmosphere) and re-radiation
downward of some of that heat.
Water vapor is the most abundant
greenhouse gas, followed by carbon dioxide
and other trace gases. Without a natural
greenhouse effect, the temperature of the
Earth would be about zero degrees F (-18
C) instead of its present 57F (14 C)
So, the concern is not with the fact that we
have a greenhouse effect, but whether
human activities are leading to an
enhancement of the greenhouse effect by
the emission of greenhouse gases through
fossil fuel combustion and deforestation.
Climate Change andGlobal
Warming
Global warming is the increase in the
average temperature of the Earth's nearsurface air and oceans since the midtwentieth century, and its projected
continuation. Increasing global temperature
will cause sea level to rise, and is expected
to increase the intensity of extreme weather
events and to change the amount and
pattern of precipitation.