Chapter 18 Air Pollution And Water pollution Class 8 Notes | EduRev

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Class 8 : Chapter 18 Air Pollution And Water pollution Class 8 Notes | EduRev

 Page 1


Chapter – 18 Pollution of Air and Water 
 
Pollution – The contamination of air, water or soil by unwanted substances  
Pollutants – The unwanted substances that contaminate air, water or soil. 
 
Air Pollution 
The pollution of air by unwanted substances such as oxides of carbon, nitrogen, sulphur and dust particles. 
Air Pollutants – Smoke and dust arising from human activities such as vehicles and factories, and natural factors 
such as volcanic eruptions and forest fires.                                                                                         Carbon 
monoxide is a poisonous gas produced by incomplete combustion of fossil fuels such as petrol and diesel.                               
Smog – the thick white layer formed in winters due to the mixing of smoke with fog is known as smog.  
Greenhouse effect – The phenomenon of trapping of sunrays of the sun by the Earth’s atmosphere to keep the 
Earth surface warm is known as greenhouse effect. Greenhouse effect prevents the temperature of Earth from 
dropping significantly at night and makes life possible on our planet. 
 
Harmful effects of global warming 
1. Global warming – The rise in average temperature of the Earth due to increase in the concentration of 
the greenhouse gases such as carbon dioxide, methane and nitrous oxide is known as global warming. It 
leads to melting of glaciers, which can increase sea level and cause flood in low regions. 
2. Acid rain – The oxides of nitrogen sulphur and nitrogen reacts with rain water to form acid, which comes 
down during acid rain. Acid rain can cause skin irritation, skin burns and corrodes the marbles of 
monuments. Mathura oil refinery and several other factories in the nearby area caused corrosion of the 
marble of ‘Taj Mahal’, which lead to the yellowing of Taj Mahal. 
3. Chlorofluorocarbons (CFCs) are used in refrigerators and air conditioners, and degrade the ozone layer 
present in our atmosphere. The ozone layer protects us from the harmful ultraviolet rays of the sun.  
4. Smog and air pollutants produced from factories and vehicles causes various respiratory diseases such as 
asthma and cough.  
Preventive measures 
1. Use of public transport 
2. Use of cleaner fuels such as CNG (Compressed natural gas) and LPG (Liquefied petroleum Gas) 
3. Using alternative sources of energy such as solar energy, wind energy and geothermal energy. 
4. Afforestation – Planting more trees as trees absorb carbon dioxide and release oxygen. 
 
 
Water Pollution 
The pollution of water by release of unwanted substances into the water bodies is known as water pollution 
Causes of water pollution 
Page 2


Chapter – 18 Pollution of Air and Water 
 
Pollution – The contamination of air, water or soil by unwanted substances  
Pollutants – The unwanted substances that contaminate air, water or soil. 
 
Air Pollution 
The pollution of air by unwanted substances such as oxides of carbon, nitrogen, sulphur and dust particles. 
Air Pollutants – Smoke and dust arising from human activities such as vehicles and factories, and natural factors 
such as volcanic eruptions and forest fires.                                                                                         Carbon 
monoxide is a poisonous gas produced by incomplete combustion of fossil fuels such as petrol and diesel.                               
Smog – the thick white layer formed in winters due to the mixing of smoke with fog is known as smog.  
Greenhouse effect – The phenomenon of trapping of sunrays of the sun by the Earth’s atmosphere to keep the 
Earth surface warm is known as greenhouse effect. Greenhouse effect prevents the temperature of Earth from 
dropping significantly at night and makes life possible on our planet. 
 
Harmful effects of global warming 
1. Global warming – The rise in average temperature of the Earth due to increase in the concentration of 
the greenhouse gases such as carbon dioxide, methane and nitrous oxide is known as global warming. It 
leads to melting of glaciers, which can increase sea level and cause flood in low regions. 
2. Acid rain – The oxides of nitrogen sulphur and nitrogen reacts with rain water to form acid, which comes 
down during acid rain. Acid rain can cause skin irritation, skin burns and corrodes the marbles of 
monuments. Mathura oil refinery and several other factories in the nearby area caused corrosion of the 
marble of ‘Taj Mahal’, which lead to the yellowing of Taj Mahal. 
3. Chlorofluorocarbons (CFCs) are used in refrigerators and air conditioners, and degrade the ozone layer 
present in our atmosphere. The ozone layer protects us from the harmful ultraviolet rays of the sun.  
4. Smog and air pollutants produced from factories and vehicles causes various respiratory diseases such as 
asthma and cough.  
Preventive measures 
1. Use of public transport 
2. Use of cleaner fuels such as CNG (Compressed natural gas) and LPG (Liquefied petroleum Gas) 
3. Using alternative sources of energy such as solar energy, wind energy and geothermal energy. 
4. Afforestation – Planting more trees as trees absorb carbon dioxide and release oxygen. 
 
 
Water Pollution 
The pollution of water by release of unwanted substances into the water bodies is known as water pollution 
Causes of water pollution 
1. Washing dirty clothes, animals and vehicles in the water bodies. 
2. Release of untreated waste from factories directly into the water bodies. 
3. Running away fertilizers from the factories to water bodies can pollute water. The fertilizers increases the 
growth of blue green algae in the water bodies (also called eutrophication), which can reduce the dissolved 
oxygen. This leads to the death of aquatic plants and animals. 
4. Throwing of garbage, flowers, idols of gods, and goddesses, non- biodegradable plastics and dead bodies 
in rivers. 
Ganga Action Plan 
The plan launched by government of India in 1985 with the aim of cleaning river Ganga is known as Ganga action 
plan.  
All the above factors (in causes of water pollution) are responsible for the pollution of river Ganga and poor 
enforcement of the laws and plans make the situation more severe.  
 
Potable water 
Water that is suitable for drinking is known as potable water. 
Ways to clean water: 
1. Use of candle filter and RO (reverse osmosis) filters 
2. Boiling the water 
3. Chlorination – Using small amount of chlorine tablets to the water. 
 
Preventing Water pollution 
1. Strict laws and their implementation to prevent industries from dumping waste into the rivers.  
2. Avoiding throwing of garbage, flowers, idols of gods, and goddesses, non- biodegradable plastics and 
dead bodies in rivers. 
3. Reduce, Reuse and Recycle to prevent the wastage of water. 
 
 
 
 
 
 
 
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