Chapter: Pollution of Air and Water - Class 8 PDF Download

Air Pollution

Air pollution occurs when unwanted substances mix with air, causing harm to living and non-living things. Clean air is essential for our survival, but pollution threatens its quality.

1. Air is a mixture of gases, including nitrogen, oxygen, carbon dioxide, argon, methane, ozone, and water vapour.

2. Air pollutants can come from natural sources, such as forest fires and volcanic eruptions, or human activities, such as factories, power plants, and vehicle exhausts.

3. Polluted air can cause respiratory problems and other health issues.

4. Many cities experience smog, which is a combination of smoke and fog that can lead to breathing difficulties.

5. Industries and automobiles are significant contributors to air pollution.

How does Air Get Polluted?

Air gets polluted when harmful substances, called air pollutants, contaminate it. These pollutants can come from natural sources or human activities.

1. Natural sources of air pollutants include smoke and dust from forest fires and volcanic eruptions.

2. Human activities that contribute to air pollution include factories, power plants, automobile exhausts, and the burning of firewood and dung cakes.

3. Vehicles produce high levels of pollutants, such as carbon monoxide, carbon dioxide, nitrogen oxides, and smoke.

4. Industries, such as petroleum refineries, release pollutants like sulfur dioxide and nitrogen dioxide, which can cause respiratory problems and damage the ozone layer.

5. Burning fossil fuels and using chlorofluorocarbons (CFCs) in refrigerators, air conditioners, and aerosol sprays also contribute to air pollution.

Case Study The Taj Mahal

India's famous tourist attraction, the Taj Mahal, has become a matter of concern due to air pollution. Pollutants in the air are discolouring its white marble, affecting not just living organisms but also non-living things like buildings and monuments.

1. Industries in and around Agra, such as rubber processing, automobile, chemicals, and the Mathura oil refinery, produce pollutants like sulfur dioxide and nitrogen dioxide.

2. These gases react with water vapour in the atmosphere to form sulfuric acid and nitric acid, leading to acid rain, which corrodes the marble of the Taj Mahal.

3. The phenomenon is also called "Marble cancer."

4. Suspended particulate matter, such as soot particles emitted by the Mathura oil refinery, contributes to the yellowing of the marble.

5. The Supreme Court has taken steps to save the Taj Mahal, such as ordering industries to switch to cleaner fuels like CNG and LPG and requiring automobiles to use unleaded petrol in the Taj zone.

Greenhouse Effect

The greenhouse effect is the process by which the Earth's atmosphere traps radiation from the sun, warming the planet. While this process is essential for life on Earth, an excess of greenhouse gases, such as carbon dioxide, can lead to global warming.

1. Carbon dioxide, methane, nitrous oxide, and water vapour are greenhouse gases that contribute to the greenhouse effect.

2. Human activities, such as burning fossil fuels and deforestation, increase the amount of carbon dioxide in the atmosphere, contributing to global warming.

3. Global warming has become a major concern for governments worldwide, leading to agreements like the Kyoto Protocol to reduce greenhouse gas emissions.

4. Even small increases in the Earth's temperature can have serious effects on the environment and ecosystems.

5. For example, global warming has caused the Gangotri glacier in the Himalayas to start melting.

What can be Done?

There are several ways to reduce air pollution, such as switching to cleaner fuels, conserving energy, and planting trees. Small contributions can make a significant difference in improving the environment.

1. Cities like Delhi have reduced air pollution by switching to cleaner fuels like CNG and unleaded petrol.

2. Monitoring air quality and raising awareness about air pollution can help encourage people to take action.

3. Alternative energy sources, such as solar, hydropower, and wind energy, can help reduce reliance on fossil fuels.

4. Planting trees and nurturing existing ones can help absorb carbon dioxide and improve air quality.

5. Reducing waste, reusing materials, and recycling can also help minimize air pollution.

Water Pollution

Water pollution occurs when harmful substances, such as sewage, toxic chemicals, and silt, mix with water, affecting its quality and making it unsuitable for use. Water pollutants can have severe consequences for both the environment and human health.

1. Water is a precious resource, but pollution threatens its quality and availability.

2. Activities like washing clothes, bathing, and industrial processes can introduce pollutants into water sources.

3. Harmful substances that pollute water are called water pollutants.

4. Water pollution can have severe consequences for aquatic life, ecosystems, and human health.

5. Pollution can also affect the quality of groundwater, making it unsafe for drinking or agricultural use.

How does Water Get Polluted?

Water gets polluted when harmful substances, such as sewage, toxic chemicals, and silt, mix with it. Industrial processes, agricultural activities, and human activities like bathing and washing can all introduce pollutants into water sources.

1. Industries, such as oil refineries, paper factories, textile and sugar mills, and chemical factories, can discharge harmful chemicals into rivers and streams, causing water pollution.

2. Agricultural activities, such as the use of pesticides and weedicides, can also introduce pollutants into water sources.

3. Polluted water can have severe consequences for aquatic life, ecosystems, and human health.

4. Untreated sewage can introduce bacteria, viruses, fungi, and parasites into water sources, leading to diseases like cholera, typhoid, and jaundice.

5. Pollution can also affect the quality of groundwater, making it unsafe for drinking or agricultural use.

What is Potable Water and How is Water Purified?

Potable water is water that is suitable for drinking. It is essential to purify water before drinking, for example, by boiling or using chemical treatments like chlorination.

1. Water can be purified by physical and chemical processes, such as boiling, filtration, and chlorination.

2. Boiling water kills germs and other microorganisms that may be present.

3. Chlorination is a chemical method for purifying water, which involves adding chlorine tablets or bleaching powder to the water.

4. Municipal bodies treat water before supplying it to households to ensure its safety for drinking and other uses.

5. It is essential to use the appropriate amount of chlorine or other treatments to ensure water safety without introducing harmful levels of chemicals.

What Can be Done?

There are several ways to reduce water pollution, such as enforcing regulations on industrial waste disposal, conserving water, and reusing water for various purposes. Individual actions can make a significant difference in protecting our water resources.

1. Strictly implementing laws for industrial waste disposal can prevent polluted water from being discharged directly into rivers and lakes.

2. Installing water treatment plants in industrial areas can help reduce water pollution.

3. At an individual level, conserving water and not wasting it can help protect our water resources.

4. Reusing water for various purposes, such as using water from washing vegetables to watering plants, can help reduce waste and pollution.

5. Reducing pollution is essential for the survival of our planet and the quality of our daily lives.

Related Questions and Anwers:

MCQs

1. Which of the following is NOT a component of air?

a. Nitrogen

b. Oxygen

c. Carbon dioxide

d. Hydrogen

Answer: d. Hydrogen

2. Which of these is an example of a natural source of air pollution?

a. Forest fires

b. Factories

c. Vehicle exhaust

d. Burning of firewood

Answer: a. Forest fires

3. What is the term used for the combination of smoke and fog that causes breathing difficulties in cities?

a. Haze

b. Smog

c. Fog

d. Smoke

Answer: b. Smog

4. The phenomenon of acid rain corroding the marble of the Taj Mahal is also called:

a. Marble decay

b. Marble corrosion

c. Marble cancer

d. Marble erosion

Answer: c. Marble cancer

5. Which of the following is NOT a greenhouse gas?

a. Carbon dioxide

b. Methane

c. Nitrous oxide

d. Nitrogen

Answer: d. Nitrogen

Short Question Answers:

1. What are the consequences of air pollution on human health?

Answer: Air pollution can cause respiratory problems and other health issues, such as asthma, bronchitis, and lung cancer.

2. What are some human activities that contribute to air pollution?

Answer: Human activities that contribute to air pollution include factories, power plants, automobile exhausts, and burning of firewood and dung cakes.

3. How does air pollution affect the Taj Mahal?

Answer: Air pollution causes the white marble of the Taj Mahal to become discoloured and corroded due to acid rain and suspended particulate matter.

4. What is the greenhouse effect, and how does it relate to global warming?

Answer: The greenhouse effect is the process by which the Earth's atmosphere traps radiation from the sun, warming the planet. An excess of greenhouse gases, such as carbon dioxide, can lead to global warming.

5. What are some ways to reduce water pollution?

Answer: Ways to reduce water pollution include enforcing regulations on industrial waste disposal, conserving water, reusing water for various purposes, and installing water treatment plants in industrial areas.