Pollution is the introduction of pollutants (whether chemical substances, or energy such as noise, heat, or light) into the environment to such a point that its effects become harmful to human health, other living organisms, or the environment. Pollution control is a term used in environmental management. It means the control of emissions and effluents into air, water or soil.

Without pollution controls the undesirable waste products from human consumption, industrial production, agricultural activities, mining, transportation and other sources will accumulate or disperse and degrade the natural environment. In the hierarchy of controls, pollution prevention and waste minimization are more desirable than pollution control.

Pollution control devices

1. Dust collection systems

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2. Scrubbers

3. Sewage treatment and Wastewater treatment

4. Vapor recovery systems

The major forms of pollution are Air pollution, the release of chemicals and particulates into the atmosphere. Water pollution via surface runoff, leaching to groundwater, liquid spills, wastewater discharges, eutrophication and littering. Soil contamination occurs when chemicals are released by spill or underground storage tank leakage. Radioactive contamination, added the wake of 20th century discoveries in atomic physics. Noise pollution, which encompasses roadway noise, aircraft noise, industrial noise as well as high-intensity sonar. Visual pollution, which can refer to the presence of overhead power lines, motorway billboards, scarred landforms (as from strip mining), open storage of trash or municipal solid waste.

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Thermal pollution is a temperature change in natural water bodies caused by human influence, such as use of water as coolant in a power plant. Motor vehicle emissions are one of the leading causes of air pollution. Some of the more common soil contaminants are chlorinated hydrocarbons (CFH), heavy metals (such as chromium, cadmium-found in rechargeable batteries, and lead-found in lead paint, aviation fuel and still in some countries, gasoline), MTBE, zinc, arsenic and benzene. Pollution can also be the consequence of a natural disaster.

For example, hurricanes often involve water contamination from sewage, and petrochemical spills from ruptured boats or automobiles. Larger scale and environmental damage is not uncommon when coastal oil rigs or refineries are involved. Some sources of pollution, such as nuclear power plants or oil tankers, can produce widespread and potentially hazardous releases when accidents occur. In the case of noise pollution the dominant source class is the motor vehicle- producing about ninety percent of all unwanted noise worldwide. Humankind has some effect upon the natural environment since the Paleolithic era during which the ability to generate fire was acquired.

In the Iron Age, use of tooling led to the practice of metal grinding on small scale and resulted in minor accumulations discarded material probably easily dispersed without too much impact. Human wastes would have polluted rivers or water sources to some degree. However, these effects could be expected predominantly to be dwarfed by the natural world. But gradually increasing populations and the proliferation of basic industrial processes saw the emergence of a civilization that began to have a much greater collective impact on its surroundings.

It was to be expected that the beginnings of environmental awareness would occur in the more developed cultures, particularly in the densest urban centers. The first medium warranting official policy measures in the emerging western world would be the most basic: the air we breathe. The earliest precursor of pollution generated by life forms would have been a natural function of their existence. The attendant consequences on viability and population levels fell within the sphere of natural selection.

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These would have included the demise of a population locally or ultimately, species extinction. Processes that were untenable would have resulted in a new balance brought about by changes and adaptations. At the extremes, for any form of life, consideration of pollution is superseded by that of survival. But now with an enormous population worldwide and wastes being produced in trillions of tonnes by the day the ability of nature to assimilate these wastes is drastically effected.

Nature alone can now not balance itself, but requires our help and co-operation. So let us all join hands and urge people worldwide to combat Pollution and save Mother Earth for a better future. A tsunami is a series of waves created when a body of water, such as an ocean, is rapidly displaced. Earthquakes, mass movements above or below water, volcanic eruptions and other underwater explosions, landslides, large meteoroid or asteroid impacts and testing with nuclear weapons at sea all have the potential to generate a tsunami.

The effects of a tsunami can range from unnoticeable to devastating. The term tsunami comes from the Japanese words meaning harbor and wav. The term was created by fishermen who returned to port to find the area surrounding their harbor devastated, although they had not been aware of any wave in the open water.