Definition of Air PollutionDefinition 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 PollutantsSources 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 Motor vehicles produce high levels of

carbon monoxides (CO) and a major source carbon monoxides (CO) and a major source of hydrocarbons (HC) and of hydrocarbons (HC) and

nitrogen oxides (NOnitrogen oxides (NOxx). ).

Whereas, fuel combustion in stationary Whereas, fuel combustion in stationary sources is the dominant source of sources is the dominant source of

sulfur dioxide (SOsulfur dioxide (SO22). ).

Carbon Dioxide - Carbon Dioxide - COCO22

Carbon dioxide (COCarbon dioxide (CO22) is one of the major ) is one of the major

pollutants in the atmosphere. Major sources pollutants in the atmosphere. Major sources of COof CO22 are fossil fuels burning and are fossil fuels burning and

deforestation. COdeforestation. CO22

a greenhouse gas a greenhouse gas

emitted from emitted from

combustion. combustion.

Carbon Monoxide -COCarbon Monoxide -CO

Carbon monoxide is colourless, odourless, Carbon monoxide is colourless, odourless, non-irritating but very poisonous gas. non-irritating but very poisonous gas.

It is a product by incomplete combustion of It is a product by incomplete combustion of fuel such as natural gas, coal or wood. fuel such as natural gas, coal or wood. Vehicular exhaust is a major source of Vehicular exhaust is a major source of carbon monoxide. carbon monoxide.

N0N0XX - nitric oxide (N0) and - nitric oxide (N0) and

nitrogen dioxide (N0nitrogen dioxide (N022)) Natural component of the Earth's atmosphere. Natural component of the Earth's atmosphere. Important in the formation of both acid precipitation and Important in the formation of both acid precipitation and

photochemical smog (ozone), and causes nitrogen photochemical smog (ozone), and causes nitrogen loading. loading.

Comes from the burning of biomass and fossil fuels. Comes from the burning of biomass and fossil fuels. 30 to 50 million tons per year from human activities, and 30 to 50 million tons per year from human activities, and

natural 10 to 20 million tons per year. natural 10 to 20 million tons per year. Average residence time in the atmosphere is days. Average residence time in the atmosphere is days. Has a role in reducing stratospheric ozone.Has a role in reducing stratospheric ozone.

Sulfur Oxides - SOSulfur Oxides - SOxx

Sulfur oxides (SOx) especially (SOx) especially sulfur dioxide are emitted from burning of coal and oil. are emitted from burning of coal and oil.

At sufficiently high concentrations, sulfur At sufficiently high concentrations, sulfur dioxide irritates the upper respiratory tract of dioxide irritates the upper respiratory tract of human beings because potential effect of human beings because potential effect of sulfur dioxide is to make breathing more sulfur dioxide is to make breathing more difficult by causing the finer air tubes of the difficult by causing the finer air tubes of the lung to constrict.lung to constrict.

Chlorofluorocarbons (CFCs)Chlorofluorocarbons (CFCs)

CFCs are lowering the average CFCs are lowering the average concentration of ozone in the stratosphere.concentration of ozone in the stratosphere.

Spray cans, discarded or leaking Spray cans, discarded or leaking refrigeration and air conditioning refrigeration and air conditioning equipment, and the burning plastic foam equipment, and the burning plastic foam products release the CFCs into the products release the CFCs into the atmosphere. Depending on the type, atmosphere. Depending on the type, CFCs stay in the atmosphere from 22 to CFCs stay in the atmosphere from 22 to 111 years. 111 years.

SmogSmog

This smog is created by burning coal and heavy This smog is created by burning coal and heavy oil that contain sulfur impurities in power plants, oil that contain sulfur impurities in power plants, industrial plants, etc... industrial plants, etc... The smog consists mostly of a mixture of sulfur The smog consists mostly of a mixture of sulfur dioxide and fog. Suspended droplets of sulfuric dioxide and fog. Suspended droplets of sulfuric acid are formed from some of the sulfur dioxide, acid are formed from some of the sulfur dioxide, and a variety of suspended solid particles. and a variety of suspended solid particles. This smog is common during the winter in cities This smog is common during the winter in cities such as London, Chicago, Pittsburgh. When such as London, Chicago, Pittsburgh. When these cities burned large amounts of coal and these cities burned large amounts of coal and heavy oil without control of the output, large-scale heavy oil without control of the output, large-scale problems were witnessed. problems were witnessed.

In 1952 London, England, 4,000 people died In 1952 London, England, 4,000 people died as a result of this form of fog. Today coal as a result of this form of fog. Today coal and heavy oil are burned only in large and heavy oil are burned only in large boilers and with reasonably good control or boilers and with reasonably good control or tall smokestacks so that industrial smog is tall smokestacks so that industrial smog is less of a problem.less of a problem.

Smog can form in almost any climate Smog can form in almost any climate where industries or cities release large where industries or cities release large amounts of air pollution.amounts of air pollution.

Volatile Organic Compounds (VOC), Volatile Organic Compounds (VOC), such as hydrocarbon fuel vapors and such as hydrocarbon fuel vapors and solvents.solvents.

Toxic metals such as lead, cadmium and Toxic metals such as lead, cadmium and copper.copper.

Ammonia emitted from agricultural Ammonia emitted from agricultural processes.processes.

Odors such as from garbage, sewage Odors such as from garbage, sewage and industrial processes.and industrial processes.

Radioactive pollutants.Radioactive pollutants.

Secondary Pollutants:Secondary Pollutants:

Ground level ozone (OGround level ozone (O33) formed from ) formed from

NONOxx and VOC. and VOC.

Peroyacetyl (PAN) similarly formed from Peroyacetyl (PAN) similarly formed from NONOxx and VOC. and VOC.

Pollutions from power plants, cars, and Pollutions from power plants, cars, and other transportation is a well-known other transportation is a well-known contributor to outdoor air pollution.contributor to outdoor air pollution.

But indoor air pollution is often worse; it But indoor air pollution is often worse; it can be up to 10 times worse for you than can be up to 10 times worse for you than the air outside.the air outside.

Indoor Air PollutionIndoor Air Pollution

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 micro-organisms and particulates

Major Indoor Air PollutantsMajor Indoor Air Pollutants

IAQ for Offices and Public Places

Health EffectsHealth EffectsAir 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 ImpactsEnvironmental Impacts

Pollutants such as sulfur dioxide, nitrogen Pollutants such as sulfur dioxide, nitrogen oxides, ozone and peroxyacl nitrates oxides, ozone and peroxyacl nitrates (PANs), cause direct damage to leaves of (PANs), cause direct damage to leaves of crop plants and trees when they enter leaf crop plants and trees when they enter leaf pores (stomates). pores (stomates).

Trees play an important role in producing Trees play an important role in producing oxygen from carbon dioxide. oxygen from carbon dioxide.

EffectsEffects

Acid RainAcid RainGreenhouse EffectGreenhouse EffectClimate ChangeClimate ChangeGlobal WarmingGlobal 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 RainAcid 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 DepositionWet 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 other living things that rely on the water.

Dry DepositionIn 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 near-surface air and oceans since the mid-twentieth 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.