Pollution of Air and Water class 8 Notes Science

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Class 8 Science notes Chapter 18 Pollution of Air and Water

Download CBSE class 8th revision notes for chapter 18 Pollution of Air and Water in PDF format for free. Download revision notes for Pollution of Air and Water class 8 Notes and score high in exams. These are the Pollution of Air and Water class 8 Notes prepared by team of expert teachers. The revision notes help you revise the whole chapter 18 in minutes. Revision notes in exam days is one of the best tips recommended by teachers during exam days.

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CBSE Class 8 Revision Notes Science Pollution of Air and Water

Pollution: An undesirable change in the physical, chemical or biological characteristics of air, water and land that may be harmful to human life and other animals, living conditions, industrial processes and cultural assets.

Pollutants: The agents that pollute our environment are called pollutants. Pollutants are the substances which contaminate air, water, and land. For eg. smoke, dust, fog and gases like sulphur dioxide and nitrogen dioxide.

Air pollution is the contamination of air by impurities which may have a harmful impact on the living organisms and the non-living components.

Sources of Air Pollution:

Natural Sources: Smoke and dust arising from forest fires or volcanic eruptions. Methane gas arising from decaying organic matter.

Man-made Sources: Exhaust gases from factories, power plants and automobiles.

Carbon monoxide, nitrogen oxides, carbon dioxide, methane and sulphur dioxide  are the major pollutants of air.

Smog is a mix in the air of smoke and chemicals with fog. The chemical components of smog can include ozone, sulphur dioxide, nitrogen dioxide and carbon monoxide. Smog can trigger breathing difficulties like asthma and coughing.

Steps to prevent air pollution:

•  Use of fuels like CNG and unleaded petrol in automobiles.
•  Switching to alternative fuels, like solar energy, hydropower and wind energy.
•  Planting trees.
•  Traveling to school on a bicycle or on public transport or car pooling.
•  Avoiding the burning of leaves, trash and vegetable matter.
•  Restricting cigarette smoking.

Increasing levels of greenhouse gases like CO2, CFC (Chloroflorocarbon) are leading to global warming. Excessive use of CFCs damages ozone layer which protects the earth from harmful UV rays emitted by the sun.

Greenhouse Effect and Global Warming:

The sun’s rays warm the earth’s surface. A part of the radiation that falls on the earth is absorbed by it  and a part is reflected back into space. A part of the reflected radiation is
trapped by the atmosphere due to presence of gases like water vapor, carbon dioxide, methane, nitrous oxide etc known as greenhouse gases. This is known as greenhouse effect.

The trapped radiations further warm the earth and have adverse effects such as melting of glaciers and increasing sea levels. This phenomenon is known as global warming.

Water pollution is the contamination of water by objectionable and harmful substances  such as sewage, toxic chemicals, silt, etc.

Sewage, agricultural chemicals and industrial waste are some of the major contaminants of water.

Water which is purified and fit for drinking is known as potable water.

Water is a precious natural resource. We must learn to conserve it.

Pollution of Air and Water class 8 Notes Science

Pollution of Air and Water class 8 Notes Science. CBSE quick revision note for class-8 Science, Chemistry, Math’s, Biology and other subject are very helpful to revise the whole syllabus during exam days. The revision notes covers all important formulas and concepts given in the chapter. Even if you wish to have an overview of a chapter, quick revision notes are here to do if for you. These notes will certainly save your time during stressful exam days.

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