Air pollution for environment students.

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Topic: Air Pollution, pollutants, sources, effect, greenhouse gases, global warming and climate
change.
Air pollution: Air pollution is the introduction of particulates, biological molecules, or other
harmful gases into Earth's atmosphere, causing disease, death to humans, damage to other living
organisms such as food crops, or the natural or built environment.
Types of Air Pollution Sources:
There are four main types of air pollution sources:
 mobile sources – such as cars, buses, planes, trucks, and trains
 stationary sources – such as power plants, oil refineries, industrial facilities, and
factories
 area sources – such as agricultural areas, cities, and wood burning fireplaces
 natural sources – such as wind-blown dust, wildfires, and volcanoes
Mobile sources account for more than half of all the air pollution in the United States and the
primary mobile source of air pollution is the automobile, according to the Environmental
Protection Agency.
Stationary sources, like power plants, emit large amounts of pollution from a single location,
these are also known as point sources of pollution.
Area sources are made up of lots of smaller pollution sources that aren't a big deal by
themselves but when considered as a group can be.
Natural sources can sometimes be significant but do not usually create ongoing air pollution
problems like the other source types can.
Anthropogenic Sources 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. We rely on them to fulfill our daily basic needs of transportation. But, there overuse is
killing our environment as dangerous gases are polluting the environment. Carbon Monoxide
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 manmade
processes.

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2. Agricultural activities: Ammonia is a very common by product from agriculture related
activities and is one of the most hazardous gases in the atmosphere. 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: Manufacturing industries release large amount of
carbon monoxide, hydrocarbons, organic compounds, and chemicals into the air thereby
depleting the quality of air. Manufacturing industries can be found at every corner of the earth
and there is no area that has not been affected by it. Petroleum refineries also release
hydrocarbons and various other chemicals that pollute the air and also cause land pollution.
4. Mining operations: Mining is a process wherein minerals below the earth are extracted using
large equipments. During the process dust and chemicals are released in the air causing massive
air pollution. This is one of the reasons which are responsible for the deteriorating health
conditions of workers and nearby residents.
5. Indoor air pollution: Household cleaning products, painting supplies emit toxic chemicals in
the air and cause air pollution. Have we ever noticed that once we paint walls of war house, it
creates some sort of smell which makes it literally impossible for us to breathe.
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.
Natural Sources of Air Pollution:
The natural sources of air pollution emissions include:
 Volcanoes: Volcanic activity produces smoke, ash, carbon dioxide, sulfur dioxide and
other air pollutants.
 Geysers: The air pollutants emitted by geysers include hydrogen sulfide, arsenic and
other heavy metals.
 Digestive gases: Methane and other gases generated by the digestion of food and emitted
by animals such as cattle.
 Oceans, Rivers and Estuaries: These are sources of methane emissions thought to be
caused by the digestive systems of marine life, methanogenesis in sediments and drainage
areas along coastal regions, and possibly seepage from methane hydrates on the ocean
floors.
 Dust: Windblown dust from areas with little or no vegetation such as desert areas.
 Sea salt: Wind-blown sea water which evaporates in the atmosphere and releases sodium
chloride and other particulates into the atmosphere.
 Radioactive decay: Radon gas is released into the atmosphere by radioactive decay
occurring in the Earth's crust.
 Forest fires: Forest fires created by lightning, or other natural causes, result in the
formation and release of smoke, ash, dust, carbon dioxide, nitrogen oxides and other air
pollutants.

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 Plants and trees: Biogenic sources such as pine trees and certain other plants and trees
which release volatile organic compounds (VOC). About 80% of the overall emissions of
VOC are from biogenic sources.
 Wetlands: Microbial action in wetlands result in significant amounts of methane being
formed and released to the atmosphere. In fact, wetlands are the largest natural source of
methane emissions.
 Termites: Termites are the second largest natural source of methane emissions. The
methane is produced by their normal digestive process.
 Lightning: Lightning converts atmospheric nitrogen to nitrogen oxides.
 Soil out gassing: Another biogenic source wherein microbial action in soils result in the
formation and release of significant amounts of nitrogen oxides.
Effects of Air pollution
1. Respiratory and heart problems: 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. 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: Another direct effect is the immediate alterations that the world is
witnessing due to Global warming. 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: Harmful gases like nitrogen oxides and sulfur oxides are released into the
atmosphere during the burning of fossil fuels. 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: 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. The green colored algae that are present on lakes and ponds is due to
presence of this chemical only.
5. Effect on Wildlife: Just like humans, animals also face some devastating effects of air
pollution. 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: 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.

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Effect on Human Health:
Ozone (O3)
Nature and Sources of the Pollutant: Ground-level ozone (the primary constituent of smog) is
the most complex, difficult to control, and pervasive of the six principal pollutants. Unlike other
pollutants, ozone is not emitted directly into the air by specific sources. Ozone is created by
sunlight acting on nitrogen oxides (NOx) and volatile organic compound (VOC) emissions in the
air. There are literally thousands of sources of these gases. Some of the more common sources
include gasoline vapors, chemical solvents, combustion products of various fuels, and consumer
products. They can originate from large industrial facilities, gas stations, and small businesses
such as bakeries and dry cleaners. Often these "precursor" gases are emitted in one area, but the
actual chemical reactions, stimulated by sunlight and temperature, take place in another.
Combined emissions from motor vehicles and stationary sources can be carried hundreds of
miles from their origins, forming high ozone concentrations over very large regions.
Approximately 50 million people lived in counties with air quality levels above EPA's health-
based national air quality standard in 1994. The highest levels of ozone were recorded in Los
Angeles. High levels also persist in other heavily populated areas like the Texas Gulf Coast and
much of the Northeast.
Health and Other Effects: Scientific evidence indicates that ground-level ozone not only affects
people with impaired respiratory systems (such as asthmatics), but healthy adults and children as
well. Exposure to ozone for 6 to 7 hours, even at relatively low concentrations, significantly
reduces lung function and induces respiratory inflammation in normal, healthy people during
periods of moderate exercise. It can be accompanied by symptoms such as chest pain, coughing,
nausea, and pulmonary congestion. Recent studies provide evidence of an association between
elevated ozone levels and increases in hospital admissions for respiratory problems in several
U.S. cities. Results from animal studies indicate that repeated exposure to high levels of ozone
for several months or more can produce permanent structural damage in the lungs. EPA's health-
based national air quality standard for ozone is 0.12 ppm (measured at the highest hour during
the day). Ozone is also responsible for several billion dollars of agricultural crop yield loss in the
U.S. each year.
Nitrogen Dioxide (NO2)
Nature and Sources of the Pollutant: Nitrogen dioxide belongs to a family of highly reactive
gases called nitrogen oxides (NOx). These gases form when fuel is burned at high temperatures,
and come principally from motor vehicle exhaust and stationary sources such as electric utilities
and industrial boilers. A suffocating, brownish gas, nitrogen dioxide is a strong oxidizing agent
that reacts in the air to form corrosive nitric acid, as well as toxic organic nitrates. It also plays a
major role in the atmospheric reactions that produce ground-level ozone (or smog).
Health and Other Effects: Nitrogen dioxide can irritate the lungs and lower resistance to

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respiratory infections such as influenza. The effects of short-term exposure are still unclear, but
continued or frequent exposure to concentrations that are typically much higher than those
normally found in the ambient air may cause increased incidence of acute respiratory illness in
children. EPA's health-based national air quality standard for NO2 is 0.053 ppm (measured as an
annual average). Nitrogen oxides are important in forming ozone and may affect both terrestrial
and aquatic ecosystems. Nitrogen oxides in the air are a potentially significant contributor to a
number of environmental effects such as acid rain and eutrophication in coastal waters like the
Chesapeake Bay. Eutrophication occurs when a body of water suffers an increase in nutrients
that reduce the amount of oxygen in the water, producing an environment that is destructive to
fish and other animal life.
Particulate Matter (PM-10 and PM-2.5)
Nature and Sources of the Pollutants: Particulate matter is the term for solid or liquid particles
found in the air. Some particles are large or dark enough to be seen as soot or smoke. Others are
so small they can be detected only with an electron microscope. Because particles originate from
a variety of mobile and stationary sources (diesel trucks, wood stoves, power plants, etc.), their
chemical and physical compositions vary widely.
Health and Other Effects: In 1987, EPA replaced the earlier Total Suspended Particulate (TSP)
air quality standard with a PM-10 standard. The standard focuses on smaller particles that are
likely responsible for adverse health effects because of their ability to reach the lower regions of
the respiratory tract. The PM-10 standard includes particles with a diameter of 10 micrometers or
less (0.0004 inches or one-seventh the width of a human hair). EPA's health-based national air
quality standard for PM-10 is 50 micrograms per cubic meter (measured as an annual average)
and 150 micrograms per cubic meter (measured as a daily average). In 1997, EPA promulgated a
PM-2.5 standard which includes particles with a diameter of 2.5 microns or less. These smaller
particles have the best chance of reaching the lower respiratory tract. The health-based national
ambient air quality standard for PM-2.5 is 15 micrograms per cubic meter (measured as an
annual average) and 65 micrograms per cubic meter (measured as a daily average).
Major concerns for human health from exposure to particulate matter are: effects on breathing
and respiratory systems, damage to lung tissue, cancer, and premature death. The elderly,
children, and people with chronic lung disease, influenza, or asthma, tend to be especially
sensitive to the effects of particulate matter. Acidic particulate matter can also damage manmade
materials and is a major cause of reduced visibility in many parts of the U.S.
Sulfur Dioxide (SO2)
Nature and Sources of the Pollutant: Sulfur dioxide belongs to the family of sulfur oxide gases
(SOx). These gases are formed when fuel containing sulfur (mainly coal and oil) is burned, and
during metal smelting and other industrial processes.

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Health and Other Effects: The major health concerns associated with exposure to high
concentrations of SO2 include effects on breathing, respiratory illness, alterations in pulmonary
defenses, and aggravation of existing cardiovascular disease. Major subgroups of the population
that are most sensitive to SO2 include asthmatics and individuals with cardiovascular disease or
chronic lung disease (such as bronchitis or emphysema) as well as children and the elderly.
EPA's health-based national air quality standard for SO2 is 0.03 ppm (measured on an annual
average) and 0.14 ppm (measured over 24 hours). Emissions of SO2 also can damage the foliage
of trees and agricultural crops. EPA has a secondary SO2 national ambient air quality standard of
0.50 ppm (measured over 3 hours) designed to prevent this type of environmental deterioration.
Together, SO2 and NOX are the major precursors to acid rain, which is associated with the
acidification of lakes and streams, accelerated corrosion of buildings and monuments, and
reduced visibility.
Lead (Pb)
Nature and Sources of the Pollutant: Smelters and battery plants are the major sources of the
pollutant "lead" in the air. The highest concentrations of lead are found in the vicinity of
nonferrous smelters and other stationary sources of lead emissions.
Health Effects: Exposure to lead mainly occurs through inhalation of air and ingestion of lead in
food, paint, water, soil, or dust. Lead accumulates in the body in blood, bone, and soft tissue.
Because it is not readily excreted, lead can also affect the kidneys, liver, nervous system, and
other organs. Excessive exposure to lead may cause anemia, kidney disease, reproductive
disorders, and neurological impairments such as seizures, mental retardation, and/or behavioral
disorders. Even at low doses, lead exposure is associated with changes in fundamental
enzymatic, energy transfer, and other processes in the body. Fetuses and children are especially
susceptible to low doses of lead, often suffering central nervous system damage or slowed
growth. Recent studies show that lead may be a factor in high blood pressure and subsequent
heart disease in middle-aged white males. Lead may also contribute to osteoporosis in
postmenopausal women. EPA's health-based national air quality standard for lead is 1.5
micrograms per cubic meter [measured as a quarterly average].
Carbon Monoxide (CO)
Nature and Sources of the Pollutant: Carbon monoxide is a colorless odorless poisonous gas
formed when carbon in fuels is not burned completely. It is a byproduct of motor vehicle
exhaust, which contributes more than two-thirds of all CO emissions nationwide. In cities,
automobile exhaust can cause as much as 95 percent of all CO emissions. These emissions can
result in high concentrations of CO, particularly in local areas with heavy traffic congestion.
Other sources of CO emissions include industrial processes and fuel combustion in sources such
as boilers and incinerators. Despite an overall downward trend in concentrations and emissions

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of CO, some metropolitan areas still experience high levels of CO.
Health and Other Effects: Carbon monoxide enters the bloodstream and reduces oxygen
delivery to the body's organs and tissues. The health threat from CO is most serious for those
who suffer from cardiovascular disease. Healthy individuals are also affected, but only at higher
levels of exposure. Exposure to elevated CO levels is associated with visual impairment, reduced
work capacity, and reduced manual dexterity, poor learning ability, and difficulty in performing
complex tasks. EPA's health based national air quality standard for CO is 9 parts per million
(ppm) [measured over 8 hours].
Common Air Pollutants:
Figure: Common Air Pollutants
Carbon Monoxide (CO)
 Fuel combustion from vehicles and engines.
 Reduces the amount of oxygen reaching the body’s organs and tissues; aggravates heart
disease, resulting in chest pain and other symptoms.
Ground-level Ozone (O3)
 Secondary pollutant formed by chemical reaction of volatile organic compounds (VOCs)

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and NOx in the presence of sunlight.
 Decreases lung function and causes respiratory symptoms, such as coughing and
shortness of breath, and also makes asthma and other lung diseases get worse. More on
Ground Level Ozone Here
Lead (Pb)
 Smelters (metal refineries) and other metal industries; combustion of leaded gasoline in
piston engine aircraft; waste incinerators (waste burners), and battery manufacturing.
 Damages the developing nervous system, resulting in IQ loss and impacts on learning,
memory, and behavior in children. Cardiovascular and renal effects in adults and early
effects related to anemia.
Nitrogen Dioxide (NO2)
 Fuel combustion (electric utilities, big industrial boilers, vehicles) and wood burning.
 Worsens lung diseases leading to respiratory symptoms, increased susceptibility to
respiratory infection.
Particulate Matter (PM)
 This is formed through chemical reactions, fuel combustion (e.g., burning coal, wood,
diesel), industrial processes, farming (plowing, field burning), and unpaved roads or
during road constructions.
 Short-term exposures can worsen heart or lung diseases and cause respiratory problems.
Long-term exposures can cause heart or lung disease and sometimes premature deaths.
Sulfur Dioxide (SO2)
 SO2 comes from fuel combustion (especially high-sulfur coal); electric utilities and
industrial processes as well as natural occurrences like volcanoes.
 Aggravates asthma and makes breathing difficult. It also contributes to particle formation
with associated health effects.
Air pollution prevention, monitoring and solution:
Solution efforts on pollution are always a big problem. This is why prevention interventions are
always a better way of controlling air pollution. These prevention methods can either come from
government (laws) or by individual actions. In many big cities, monitoring equipment have been
installed at many points in the city. Authorities read them regularly to check the quality of air.
Let's see more below:

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Government (or community) level prevention
 Governments throughout the world have already taken action against air pollution by
introducing green energy. Some governments are investing in wind energy and solar
energy, as well as other renewable energy, to minimize burning of fossil fuels, which
cause heavy air pollution.
 Governments are also forcing companies to be more responsible with their manufacturing
activities, so that even though they still cause pollution, they are a lot controlled.
 Car manufacturing companies are also building more energy efficient cars, which pollute
less than before.
Individual Level Prevention
 Encourage wer family to use the bus, train or bike when commuting. If we all do this,
there will be fewer cars on road and less fumes.
 Use energy (light, water, boiler, kettle and fire woods) wisely. This is because lots of
fossil fuels are burned to generate electricity, and so if we can cut down the use, we will
also cut down the amount of pollution we create.
 Recycle and re-use things. This will minimize the dependence of producing new things.
Remember manufacturing industries create a lot of pollution, so if we can re-use things
like shopping plastic bags, clothing, paper and bottles, it can help.
Greenhouse Gases:
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal
infrared range. This process is the fundamental cause of the greenhouse effect. The primary
greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous
oxide, and ozone. Without greenhouse gases, the average temperature of Earth's surface would
be about 33 °C colder, which is about 59 °F below the present average of 14 °C (57 °F).
The Connection between Greenhouse Gases, Climate Change, and Global Warming
WHAT IS THE DIFFERENCE BETWEEN CLIMATE CHANGE AND GLOBAL
WARMING?
Climate change is the shift in long-term, global weather patterns due to human action; it’s not
exclusive to warming or cooling.
Climate change includes any change resulting from different factors, like deforestation or an
increase in greenhouse gases. Global warming is one type of climate change, and it refers to the
increasing temperature of the surface of Earth. According to NASA, the term global warming

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gained popular use after geochemist Wallace Broecker published a 1975 paper titled Climatic
Change: Are We on the Brink of a Pronounced Global Warming?
Since 1880, the average surface temperature of the Earth has increased by roughly 0.9 degrees
Fahrenheit, but the rate it’s increasing is faster than that, depending on which region we live in.
If we’re closer to the equator, temperatures are increasing more slowly. The fastest increase in
temperatures in the United States is in Alaska, where average temperatures have been increases
by more than 3 degrees Fahrenheit per century
HOW GREENHOUSE GASES RELATE TO CLIMATE CHANGE
Greenhouse gases are those thought to contribute to the greenhouse effect, an overall warming of
the Earth as atmospheric gases trap electromagnetic radiation from the sun that would otherwise
have been reflected back out into space.
Noteworthy greenhouse gases are methane, nitrous oxide, carbon dioxide, hydro fluorocarbons
(HFCs), per fluorocarbons (PFCs), and sulfur hexafluoride (SF6). These gases are thought to
affect the climate directly and indirectly, even though they constitute only a small fraction of the
blanket of gases that make up the atmosphere.
Currently, the composition of the atmosphere is mostly nitrogen and oxygen, with just 0.033
percent carbon dioxide and all other gases accounting for even less.

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WHICH GASES CONTRIBUTE THE MOST?
According to 2010 models cited by NASA, 20 percent of the greenhouse effect is attributed
directly to carbon dioxide and 5 percent to all other greenhouse gases. The remaining 75 percent
of the greenhouse effect is thought to be due to water vapor and clouds, which are naturally-
occurring. However, even though carbon dioxide and the other greenhouse gases are such a small
percentage of the total gas in the atmosphere, they affect when, where and how clouds form, so
greenhouse gases have some relevance when it comes to 100 percent of the greenhouse effect.
Carbon dioxide is thought to modulate the overall climate, like a atmospheric thermostat.
Some greenhouse gases are produced in natural processes, like forest fires, animal manure and
respiration, or volcanic eruptions. However, the majority of new greenhouse gases are produced
from industrial processes and energy production.
The four largest human sources of U.S. greenhouse gases in 2009 were energy, non-fuel use of
fossil fuels, natural gas production, and cement manufacture, in descending order. Non-fuel,
greenhouse gas-producing applications of fuels include industrial production like asphalt,
lubricants, waxes and other . Emissions related to cement manufacture happen when limestone
(calcium carbonate) is reacted with silica to make clinker, the lumps ground to make cement.
(Emissions of Greenhouse Gases in the United States 2009: Independent Statistics & Analysis.)