Air Pollution for Class 4 Science
Addition of hazardous materials such as poisonous gases and chemicals results into air pollution. There are different causes of air pollution such as factory emission, mining activities, deforestation, etc. In this concept, the students will understand different causes and effects of air pollution.
After reading the concept, students will be able to:
- Recall the types of pollution around us.
- Identify different pollutants.
- Compare air pollution due to automobiles and fertilisers.
- Answer what causes indoor air pollution.
- Discuss about effects of air pollution such as ozone layer depletion, global warming, etc.
- Describe what is acid rain.
- Differentiate between afforestation and deforestation.
Each concept is explained to class 4 students using descriptions, illustrations, and concept maps. After you go through a concept, assess your learning by solving the two printable worksheets given at the end of the page.
Download the worksheets and check your answers with the worksheet solutions for the concept Air Pollution provided in PDF format.
What is Pollution?
Pollution is when harmful substances like gases, smoke and chemicals are introduced into the environment that contaminates it and causes damage to the living organisms.
Types of Pollution:
The three main types of pollution are—
- Air pollution
- Water pollution
- Noise pollution
The substances that make the environment impure are called pollutants.
Examples: Sulphur dioxide, nitrogen oxides, ozone, carbon dioxide, particulate matter etc.
Pollutants can change the quality of environmental components like air and water physically, chemically and biologically.
Air pollution happens when the air gets contaminated due to harmful air pollutants like smoke, toxic gases, dust, etc., and this results in the degradation of air quality and causes serious health problems.
Causes of Air Pollution:
Motor vehicles like cars, buses, trucks emit harmful gases. The principal gas emitted by motor vehicles is carbon dioxide and some nitrous oxide. These gases cause the surrounding air to get polluted and contribute to climate change and global warming.
Chemical fertilisers give off ammonia, a very harmful gas that causes air pollution.
3. Emission from Factories:
Factories emit several gaseous pollutants like sulphur dioxide, carbon monoxide and other hydrocarbons that mix with the air causing degradation of the air quality.
4. Indoor Air Pollutants:
We are not protected from air pollution even in our homes due to indoor air pollutants like excess moisture, volatile organic compounds, carbon monoxide, and radon.
5. Mining Activities:
While mining, several harmful gases and dust particles are emitted into the surrounding air, causing air pollution.
6. Burning of Fossil Fuels:
The burning of fossil fuels emits a large amount of carbon monoxide and sulphur dioxide, both responsible for air pollution.
Deforestation is one of the primary causes of air pollution because fewer plants and trees mean less absorption of carbon dioxide. We know that increase in the amount of carbon dioxide is not suitable for our environment.
Effects of Air Pollution:
1. Ozone Layer Depletion:
Our atmosphere is divided into many layers, among which there is an ozone layer that protects the earth from the harmful radiation of the sun. However, air pollutants like chlorofluorocarbons and halons emitted by refrigerants, solvents and propellants cause the depletion of the ozone layer. As a result, the sun's harmful radiations can reach the earth’s surface.
2. Global Warming:
Due to excessive emission of greenhouse gases like carbon dioxide, methane, nitrous oxide etc., the earth is becoming hotter every year. This phenomenon is known as global warming. Due to global warming, the polar glaciers are melting, and the sea level is rising, and regions close to the sea are getting submerged.
3. Acid Rain:
Harmful air pollutants like nitrogen oxides, sulphur oxides, etc., combine with the oxygen and water in the air to form acids like nitric acid and sulphuric acid. These acids mix with rainwater and come down on the earth’s surface in the form of acid rain. Acid rain causes extensive damage to plants, animals, and human beings and wears away buildings and monuments.
4. Respiratory Diseases:
Air pollution causes many respiratory diseases like asthma, pneumonia and even lung cancer.
Controlling Air Pollution:
1. Using Renewable Energy Sources:
If we want to reduce air pollution, we should use renewable sources of energy like solar energy, geothermal energy and wind energy as these emit no toxic gases.
2. Minimizing the Use of Vehicles That Cause Pollution:
Vehicles that emit toxic gases should be avoided. Instead, the use of non-polluting vehicles like trams, electric cars etc., should be encouraged. We should also try carpooling and not use personal vehicles to travel short distances.
3. Conservation of Energy:
We should turn off our car engines when waiting at traffic signals and switch off the electric appliances when they are not being used to reduce the usage of fossil fuels because we know that the burning of fossil fuels leads to air pollution.
Afforestation or planting more trees can help improve the air quality as trees can absorb the toxic gases present in the air and reduce greenhouse gases.
Climate hange: It refers to the change in the weather of a region over a long period mainly caused by global warming.
Greenhouse Gases: These are certain gases in the atmosphere that trap energy from the sun. Without these gases, the earth would have been a colder place. However, too much greenhouse gases in the atmosphere are also not desirable as they make the earth quite hotter.
Renewable Energy Sources: These are energy sources that can be easily replenished unlike non-renewable ones which take millions of years to form and can eventually run out. Renewable sources of energy do not cause any pollution.
Did You Know?
- The different causes of air pollution are mostly man-made causes. However, air can get polluted even due to natural phenomena like volcanic eruptions and forest fires.
- It is estimated that almost 527700 people die every year in India due to air pollution.
- Indoor air pollution is considered worse than outdoor air pollution.