General Science Notes Chapter 8 Pollution Class 8 Maharashtra Board

Notes For All Chapters – General Science Class 8
1. Introduction

• Pollution is the contamination of the environment that harms humans, animals, and plants.
• It affects air, water, soil, and even sound levels.
• Pollution is caused by human activities like factories, vehicles, and deforestation.

2. Types of Pollution

1. Air Pollution

Definition: When harmful gases, smoke, and dust mix with the air, making it unsafe to breathe.

Causes:

• Smoke from factories and vehicles
• Burning of coal, wood, and garbage
• Release of harmful gases like carbon dioxide (CO₂), sulfur dioxide (SO₂), and methane (CH₄)

Effects:

• Causes breathing problems, lung diseases, and asthma
• Leads to global warming and acid rain
• Damages plants and affects agriculture

Ways to Reduce Air Pollution:

• Use public transport instead of private vehicles.
• Plant more trees to absorb carbon dioxide.
• Use clean fuels like CNG and electricity.

2. Water Pollution

Definition: When harmful substances mix with water, making it dirty and unsafe for drinking and aquatic life.

Causes:

• Dumping of sewage, plastic, and chemicals in rivers.
• Oil spills from factories and ships.
• Excessive use of fertilizers and pesticides.

Effects:

• Causes diseases like cholera and typhoid.
• Kills aquatic plants and animals.
• Pollutes drinking water sources.

Ways to Reduce Water Pollution:

• Do not throw garbage in rivers and lakes.
• Use eco-friendly fertilizers in farming.
• Treat industrial waste before releasing it into water bodies.

3. Soil Pollution

Definition: When harmful substances mix with soil, reducing its fertility and making it toxic.

Causes:

• Plastic waste and chemical pesticides.
• Dumping of industrial and household waste.
• Oil spills and deforestation.

Effects:

• Reduces crop growth and soil fertility.
• Pollutes groundwater.
• Harms animals and humans through the food chain.

Ways to Reduce Soil Pollution:

• Use organic fertilizers instead of chemicals.
• Recycle and reuse plastic to reduce waste.
• Proper waste disposal and composting.

4. Noise Pollution

Definition: Excessive loud sounds that disturb humans and animals.

Causes:

• Traffic noise from vehicles and honking.
• Loudspeakers, firecrackers, and construction.
• Factories and machinery producing high noise levels.

Effects:

• Causes stress, hearing loss, and sleep disturbances.
• Affects animals and birds, making it hard for them to communicate.
• Increases blood pressure and mental stress.

Ways to Reduce Noise Pollution:

• Use silencers in vehicles and machines.
• Avoid loudspeakers and firecrackers in residential areas.
• Plant trees to absorb noise.

3. Acid Rain

Definition: Rain that contains harmful acids due to air pollution.

Cause: Burning of fuels releases sulfur dioxide (SO₂) and nitrogen oxides (NO₂), which mix with rainwater.

Effects:

• Damages buildings and historical monuments like the Taj Mahal.
• Harms plants and forests.
• Pollutes water bodies, killing fish and aquatic life.

Ways to Prevent Acid Rain:

• Reduce the use of coal and petrol.
• Install pollution control filters in factories.
• Use renewable energy sources like solar and wind power.

4. Greenhouse Effect and Global Warming

Greenhouse Effect: Gases like carbon dioxide (CO₂), methane (CH₄), and CFCs trap heat in the Earth’s atmosphere.

Global Warming: The rise in Earth’s temperature due to pollution.

Effects:

• Melting of glaciers and polar ice caps.
• Rise in sea levels, flooding coastal areas.
• Changes in climate and rainfall patterns.

Ways to Reduce Global Warming:

• Use solar, wind, and hydro energy instead of fossil fuels.
• Plant trees to absorb carbon dioxide.
• Reduce the use of air conditioners and refrigerators that release harmful gases.

5. Ozone Layer Depletion

Ozone Layer: A protective layer in the atmosphere that absorbs harmful UV rays from the Sun.

Cause of Depletion:

• Release of CFCs (Chlorofluorocarbons) from air conditioners, refrigerators, and spray cans.

Effects:

• Increased risk of skin cancer and eye diseases.
• Affects plant growth and crops.
• Causes climate change and global warming.

Ways to Protect the Ozone Layer:

• Avoid using products with CFCs.
• Use eco-friendly refrigerators and ACs.
• Follow rules and regulations on air pollution control.

6. Preventive Measures for Pollution

Air Pollution:

• Use public transport instead of private vehicles.
• Reduce factory emissions using filters.
• Plant trees to purify the air.

Water Pollution:

• Do not dump waste and chemicals into rivers.
• Use biodegradable detergents and soaps.
• Treat sewage water before releasing it.

Soil Pollution:

• Recycle waste to reduce landfill dumping.
• Use organic fertilizers instead of chemicals.
• Avoid burning plastic and other toxic materials.

Noise Pollution:

• Use silencers in vehicles and machines.
• Avoid unnecessary honking and loud music.
• Plant trees to absorb noise.

7. Laws for Pollution Control

The Government of India has made laws to control pollution:

1. Water Pollution and Prevention Act, 1974 – Controls water pollution.
2. Air Pollution and Prevention Act, 1981 – Controls air pollution.
3. Environmental Protection Act, 1986 – Protects the environment from all types of pollution.

Pollution Control Boards

• The Central and Maharashtra Pollution Control Boards check if industries follow pollution control rules.