CBSE Class 3 General Knowledge Causes of Pollution Notes Set 01

What is pollution?

Pollution means adding harmful things to air, water or soil so that they become dirty and unsafe for living beings. The harmful things are called pollutants. Pollution harms people, animals and plants, and damages our planet. There are four main kinds: air pollution, water pollution, land (soil) pollution and noise pollution.

Air pollution

Air pollution is caused when harmful gases, smoke and dust are released into the air. Its main causes are the burning of petrol, diesel and coal, smoke from factories, smoke from vehicles, burning of garbage and dry leaves, and dust from construction and mining. Polluted air can cause coughing, breathing problems and eye irritation.

Water pollution

Water pollution happens when dirty things enter rivers, ponds, lakes and seas. The causes include waste from factories, sewage and dirty water from homes, chemical fertilisers and pesticides washed from fields, and garbage thrown into water. Drinking polluted water causes stomach illnesses, and fish and other water animals die.

Land or soil pollution

Land pollution happens when the soil is spoilt by waste. It is caused by dumping garbage and plastic, factory waste, too much use of fertilisers and chemicals, and cutting down of trees (deforestation). Polluted soil does not give good crops, and rubbish attracts flies and rats that spread diseases.

Noise pollution

Noise pollution means unwanted loud sound. It is caused by loud horns of vehicles, loudspeakers at events, construction work, factory machines and aircraft. Too much noise can cause headaches, tiredness and loss of hearing, and it disturbs animals and birds.

How can we reduce pollution?

1. Walk, cycle or use public transport instead of cars for short trips.

2. Plant trees, because they clean the air.

3. Put waste in dustbins and never throw it into rivers or drains.

4. Reduce, reuse and recycle things such as paper, glass and plastic.

5. Avoid plastic bags and carry a cloth bag.

6. Do not honk unnecessarily, and keep the volume of music low.

7. Switch off lights and fans when not in use to save energy.

Key points

1. There are four types of pollution: air, water, land and noise.

2. Most pollution is caused by human activities.

3. Small habits such as using dustbins and planting trees help.

Worked examples

Example 1. Which type of pollution is caused by smoke from factory chimneys?

Smoke goes into the air, so it is air pollution.

Example 2. Name one cause of water pollution.

Throwing garbage or dirty water from factories into a river is one cause.

Example 3. How does planting trees help?

Trees take in harmful gases and give out oxygen, so they make the air cleaner. Their roots also hold the soil together.

Effects of pollution

1. People fall ill with breathing, stomach and skin problems.

2. Animals and birds lose their homes and food, and fish die in dirty water.

3. Plants do not grow well in polluted soil and air.

4. Our weather and climate are affected, and the earth gets warmer.

Be a green helper

Make a small poster for your class with the message: Keep our earth clean. Switch off fans and lights when you leave a room, carry a water bottle from home, and plant a sapling on a special day such as Environment Day.

Quick Check Questions