Air is the Earth's atmosphere which living things breathe. It has mass and weight but no color or smell. Air pollution is the introduction of harmful substances into the atmosphere from natural or human-made sources, and can damage health, environments, and climate. The major air pollutants are particulate matter, carbon monoxide, nitrogen oxides, sulfur oxides, volatile organic compounds and ground-level ozone. Air pollutants come from sources like industrial facilities, vehicle exhaust, and agricultural burning.

2. Air is the Earth's atmosphere. It is the clear gas in which living
things live and breathe. It has an indefinite shape and volume. It
has no color or smell. It has mass and weight. It is a matter as it
has mass and weight. Air creates atmosphere pressure.

3. Air pollution is the introduction of particulates, biological molecules, and
many harmful substances into Earth's atmosphere, causing diseases, allergies, death
to humans, damage to other living organisms such as animals and food crops, or the
natural or built environment. Air pollution may come from anthropogenic or natural
sources.
The atmosphere is a complex natural gaseous system that is essential to support life
on planet Earth.

4. An air pollutant is a substance 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.
Primary pollutants are usually produced from a process, such as ash from a volcanic eruption.
Other examples include carbon monoxide gas from motor vehicle exhaust, or the 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 a
secondary pollutant. Some pollutants may be both primary and secondary: they are both emitted
directly and formed from other primary pollutants.

5. Six major airpollutants
• Carbon monoxide (CO)
• Ozone (O3)
• Nitrogen dioxide (NO2)
• Sulfur oxides (SOx)
• Carbon dioxide (CO2 )
• Lead (Pb)

6. There are two types of pollutants
• Primary pollutants
• Secondary pollutants

9. • Sulfur oxides (SOx) - particularly sulfur dioxide, a chemical compound with the formula SO2. SO2 is
produced by volcanoes and in various industrial processes. Coal and petroleum often contain sulfur
compounds, and their combustion generates sulfur dioxide. Further oxidation of SO2, usually in the
presence of a catalyst such as NO2, forms H2SO4, and thus acid rain. This is one of the causes for
concern over the environmental impact of the use of these fuels as power sources.
Sulfur Dioxide Pollution

10. • Nitrogen oxides (NOx) - Nitrogen oxides, particularly nitrogen dioxide, are expelled from high
temperature combustion, and are also produced during thunderstorms by electric discharge. They can
be seen as a brown haze dome above or a plume downwind of cities. Nitrogen dioxide is a chemical
compound with the formula NO2. It is one of several nitrogen oxides. One of the most prominent air
pollutants, this reddish-brown toxic gas has a characteristic sharp, biting odor.
 reddish, brown gas
 produced when nitric oxide combines
with oxygen in the atmosphere
 present in car exhaust and power plants
 affects lungs and causes wheezing;
increases chance of respiratory infection
Nitrogen dioxide 2014 -
global air quality levels
(released 14 December 2015)

11. • Carbon monoxide (CO) - CO is a colorless, odorless, toxic yet non-irritating gas. It is a product of
incomplete combustion of fuel such as natural gas, coal or wood. Vehicular exhaust is a major source of
carbon monoxide.
Carbon dioxide in Earth's atmosphere
if half of global-warming emissions
are not absorbed.
(NASA simulation; 9 November 2015)

12. • Volatile organic compounds (VOC) - VOCs are a well-known outdoor air pollutant. They are categorized as
either methane (CH4) or non-methane (NMVOCs). Methane is an extremely efficient greenhouse gas which
contributes to enhanced global warming. Other hydrocarbon VOCs are also significant greenhouse gases
because of their role in creating ozone and prolonging the life of methane in the atmosphere. This effect
varies depending on local air quality. The aromatic NMVOCs benzene, toluene and xylene are suspected
carcinogens and may lead to leukemia with prolonged exposure. 1,3-butadiene is another dangerous
compound often associated with industrial use.

13. • Particulates, alternatively referred to as particulate matter (PM), atmospheric particulate matter, or fine
particles, are tiny particles of solid or liquid suspended in a gas. In contrast, aerosol refers to combined
particles and gas. Some particulates occur naturally, originating from volcanoes, dust storms, forest and
grassland fires, living vegetation, and sea spray. Human activities, such as the burning of fossil fuels in
vehicles, power plants and various industrial processes also generate significant amounts of aerosols.
Averaged worldwide, anthropogenic aerosols—those made by human activities—currently account for
approximately 10 percent of our atmosphere. Increased levels of fine particles in the air are linked to
health hazards such as heart disease, altered lung function and lung cancer.

14. • Persistent free radicals connected to airborne fine particles are linked to cardiopulmonary disease.
• Toxic metals, such as lead and mercury, especially their compounds.

15. • Chlorofluorocarbons (CFCs) - harmful to the ozone layer; emitted from products are currently banned from
use. These are gases which are released from air conditioners, refrigerators, aerosol sprays, etc. On
release into the air, CFCs rise to the stratosphere. Here they come in contact with other gases and
damage the ozone layer. This allows harmful ultraviolet rays to reach the earth's surface. This can lead to
skin cancer, eye disease and can even cause damage to plants.

16. • Ammonia (NH3) - emitted from agricultural processes. Ammonia is a compound with the formula NH3. It is
normally encountered as a gas with a characteristic pungent odor. Ammonia contributes significantly to the
nutritional needs of terrestrial organisms by serving as a precursor to foodstuffs and fertilizers. Ammonia,
either directly or indirectly, is also a building block for the synthesis of many pharmaceuticals. Although in
wide use, ammonia is both caustic and hazardous. In the atmosphere, ammonia reacts with oxides of
nitrogen and sulfur to form secondary particles

17. • Odours — such as from garbage, sewage, and industrial processes Radioactive pollutants - produced by
nuclear explosions, nuclear events, war explosives, and natural processes such as the radioactive decay
of radon.

19. • Particulates created from gaseous primary pollutants and compounds in photochemical smog. Smog is a
kind of air pollution. Classic smog results from large amounts of coal burning in an area caused by a mixture
of smoke and sulfur dioxide. Modern smog does not usually come from coal but from vehicular and industrial
emissions that are acted on in the atmosphere by ultraviolet light from the sun to form secondary pollutants
that also combine with the primary emissions to form photochemical smog.
Beijing air on a 2005-day after rain (left) and a
smoggy day (right)
Santiago Chile smog winter

20. • Ground level ozone (O3) formed from NOx and VOCs. Ozone (O3) is a key constituent of the troposphere. It
is also an important constituent of certain regions of the stratosphere commonly known as the Ozone layer.
Photochemical and chemical reactions involving it drive many of the chemical processes that occur in the
atmosphere by day and by night. At abnormally high concentrations brought about by human activities
(largely the combustion of fossil fuel), it is a pollutant, and a constituent of smog.

21. • Peroxyacetyl nitrate (PAN) - similarly formed from NOx and VOCs.

22. Minor air pollutants include:
• A large number of minor hazardous air pollutants. Some of these are regulated in USA under the Clean
Air Act and in Europe under the Air Framework Directive
Nitrogen dioxide diffusion tube for air quality monitoring. Positioned in
London City.
• A variety of persistent organic pollutants, which can attach to particulates
State parties to the Stockholm Convention on Persistent Organic Pollutants

23. 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.
Anthropogenic (man-made) sources: These are mostly related to the burning of multiple types of fuel.
• Stationary sources include smoke stacks of power plants, manufacturing facilities (factories) and waste
incinerators, as well as furnaces and other types of fuel-burning heating devices. In developing and poor
countries, traditional biomass burning is the major source of air pollutants; traditional biomass includes
wood, crop waste and dung.

24. • Controlled burn practices in agriculture and forest management. Controlled or prescribed burning is a
technique sometimes used in forest management, farming, prairie restoration or greenhouse gas
abatement. Fire is a natural part of both forest and grassland ecology and controlled fire can be a tool
for foresters. Controlled burning stimulates the germination of some desirable forest trees, thus
renewing the forest.
Air pollution in New Delhi
Delhi has been
compared to a gas chamber since
November 2016.
While some attribute
this to the careless use of
firecrackers during Diwali, other
factors could be burning of solid
waste in and around Delhi,
vehicular emissions, dust by the
roadside and around construction
sites in Delhi and stubble burning
in Punjab and Haryana.
2016 Air pollution
level hit record high in New Delhi
in the past week following Diwali
celebration.
Air quality monitoring,
New Delhi, India.
Diwali is a festival of
lights and not pollution

25. • Mobile sources include motor vehicles, marine vessels, and aircraft.
• Fumes from paint, hair spray, varnish, aerosol sprays and other solvents

26. • Military resources, such as nuclear weapons, toxic gases, germ warfare and rocketry

27. • Waste deposition in landfills, which generate methane. Methane is highly flammable and may form
explosive mixtures with air. Methane is also an asphyxiant and may displace oxygen in an enclosed
space. Asphyxia or suffocation may result if the oxygen concentration is reduced to below 19.5% by
displacement.

28. Natural sources:
• Dust from natural sources, usually large areas of land with little or no vegetation
• Methane, emitted by the digestion of food by animals, for example cattle
Dust storm approaching Stratford, Texas.

29. • 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. It is considered to be a health
hazard. Radon gas from natural sources can accumulate in buildings, especially in confined areas such
as the basement and it is the second most frequent cause of lung cancer, after cigarette smoking.

30. • 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. Black gum, poplar, oak and willow are some examples of vegetation that can produce
abundant VOCs. The VOC production from these species result in ozone levels up to eight times higher
than the low-impact tree species.

31. • Volcanic activity, which produces sulfur, chlorine, and ash particulates

32. • Acid rain is a rain or any other form of precipitation that is unusually acidic,
meaning that it possesses elevated levels of hydrogen ions (low pH).
• It can have harmful effects on plants, aquatic animals and infrastructure.
• Acid rain is caused by emissions of sulfur dioxide and nitrogen oxide, which
react with the water molecules in the atmosphere to produce acids.
• Some governments have made efforts since the 1970s to reduce the release of
sulfur dioxide and nitrogen oxide into the atmosphere with positive results.
Nitrogen oxides can also be produced naturally by lightning strikes, and
sulfur dioxide is produced by volcanic eruptions.
• Acid rain has been shown to have adverse impacts on forests, freshwaters and
soils, killing insect and aquatic life-forms, causing paint to peel, corrosion of steel
structures such as bridges, and weathering of stone buildings and statues as well
as having impacts on human health.

33. Natural phenomena
• emissions from volcanoes.
• biological processes that occur on the land, in
wetlands, and in the oceans.
• electrical activity in the atmosphere such as
lightning.
• Acidic deposits have been detected in glacial ice
thousands of years old in remote parts of the
globe

34. Human activity
• The principal cause of acid rain is sulfur and nitrogen compounds from
human sources, such as electricity generation, factories, and motor
vehicles.
• Electrical power generation using coal is among the greatest contributors
to gaseous pollutions that are responsible for acidic rain.
• The gases can be carried hundreds of kilometers in the atmosphere before
they are converted to acids and deposited.
• In the past, factories had short funnels to let out smoke but this caused
many problems locally; thus, factories now have taller smoke funnels.
However, dispersal from these taller stacks causes pollutants to be carried
farther, causing widespread ecological damage.

35. Acid clouds can grow on
SO2 emissions from
refineries, as seen here in
Curaçao.
Since 1998, Harvard
University wraps some
of the bronze and
marble statues on its
campus, such as this
"Chinese stele", with
waterproof covers every
winter, in order to
protect them from
erosion caused by acid
Acid rain can have
severe effects on
vegetation. A forest
in Europe.
Effect of acid rain on statues

36. Human health effects
• Acid rain does not directly affect human health.
• The acid in the rainwater is too dilute to have direct adverse effects.
However, the particulates responsible for acid rain (sulfur dioxide and
nitrogen oxides) do have an adverse effect.
• Increased amounts of fine particulate matter in the air do contribute to heart
and lung problems including asthma and bronchitis.

37. • Ozone exists in earth’s stratosphere and is responsible for protecting humans from
harmful ultraviolet (UV) rays. 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.
Image of the largest Antarctic
ozone hole ever recorded
(September 2006), over the
Southern pole

38. Layers of the atmosphere (not to scale).
The Earth's ozone layer is mainly found
in the lower portion of the stratosphere
from approximately 20 to 30 km (12 to
19 mi).

39. Biological effects
• Ozone depletion would magnify all of the effects of UV on human health, both
positive (including production of Vitamin D) and negative (including sunburn, skin
cancer, and cataracts). In addition, increased surface UV leads to increased
tropospheric ozone, which is a health risk to humans.
NASA projections of stratospheric
ozone concentrations if
chlorofluorocarbons had not been
banned

40. • Global warming is an occurrence which results to the rise in the average
temperature of the earth's atmosphere.
• Due to extreme pollution from factories and automobiles in the earth's
atmosphere, greenhouse gases like carbon dioxide and nitrous oxide form
a thick layer in the upper atmosphere and traps the sun's rays from being
reflected back to outer space. This eventually leads to a rise in
temperatures as the sun warms the earth.
• Global warming also called the greenhouse effect occurs as a result of the
gradual increase of the air temperature in the earth's lower atmosphere.
• The gases from the greenhouses escape to the atmosphere to form a
blanket' that prevents the suns radiations from going to the stratosphere
thus keeping the earth an average of 33 degrees centigrade warmer than it
would be if this greenhouse effect did not occur.
• Some green house gases are like carbon dioxide, methane, Nitrous oxide
and Chlorofluorocarbons

41. 2015 – Warmest Global Year on Record (since 1880) – Colours indicate
temperature anomalies (NASA/NOAA; 20 January 2016).

42. Map of the Earth with a six-
metre sea level rise
represented in red.

43. Deaths from air pollution in 2004

44. • Understand the concept of Reduce, Reuse and Recycle: Air
Problems Caused By Incineration Of Waste Materials.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. Many people would like to believe that
waste disappears when it is burnt. In fact the burnt waste is
transformed into ashes and gas.
• 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.
• 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. Use energy efficient
devices. 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

45. • Emphasis on clean energy resources: 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.