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Pollution: Pollutants, Types, Strategies to save the environment from pollution, Practice Problems and FAQs

We all like to go trekking in mountain regions because these areas generally have clean air due to the presence of lush vegetation. We all enjoy our trips to these regions as the environment is clean and fresh. But have you ever walked in heavy traffic, in a crowded city? Then only you will realise the importance of the environment in the mountain regions. In most of the cities across the globe you can see piles of garbage, concrete jungles and polluted environments.

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Fig: Pollution

You know that the environment in cities is affected by pollution. Pollution is defined as an undesirable change in the physical, chemical or biological characteristics of air, water and land that may or will harmfully affect human life, other species, living conditions, cultural assets and deteriorate the raw material resources. A pollutant can be a chemical substance like plastic, greenhouse gases or a source of energy like light or noise which cause pollution. In all cases, it leads to worsening of the environment. In this article we will understand more about the types of pollution and the importance of saving the environment from pollution.

List of contents

  • Pollution
  • Pollutants
  • Types of pollution
  • Strategies to save the environment from pollution
  • Practice Problems
  • FAQs


Any undesirable change in the physical, chemical or biological characteristics of air, soil or water can be called pollution. Pollution occurs due to the presence of pollutants. Examples include water pollution, air pollution etc.

Fig: Pollution


Agents that bring about undesirable changes in the environment are called pollutants. Pollutants differ according to the type of pollution. Hence any solid, liquid or gaseous substance present in such concentration which is injurious to the environment can be a pollutant. Pollutants can be natural (sea salt particles or volcanic dust) or anthropogenic (man-made like plastics). Every year, close to 9 million people die due to complications arising from pollution.

Fig: Types of pollutants

Types of pollution

Pollution can be of different types. Some of the most common and damaging types of pollution are mentioned below.

Air pollution

Any undesirable change in the physical, chemical or biological characteristics of air is called air pollution. These pollutants are harmful to humans and other living beings. It causes damage to materials, and also leads to climate change. Some major gases that are responsible for air pollution are carbon monoxide, ammonia, sulphur dioxide, methane, nitrous oxides, carbon dioxide and chlorofluorocarbons. Pollutants can also be particulate matters like the smog-causing particles that reduce visibility in the winter months. Fossil fuels like coal and crude oil are some of the major sources of harmful gases that are released into the atmosphere.

Fig: Common air pollutants

Prevention of air pollution

Efforts to prevent air pollution include the following:

  • Proper planning of land usage.
  • Proper planning of transport infrastructure.
  • Finding alternative energy sources for fossil fuels.
  • Promote research to find out alternative sources of energy. For example, titanium dioxide has been found to have neutralising effects on nitrous oxides in the air through photocatalysis and hence making them harmless.

Water Pollution

An undesirable change in the physical, chemical or biological characteristics of water is called water pollution. Water pollution is the result of the contamination of the water bodies by human intervention. As a result, the water body becomes unusable for general use like drinking, irrigation, or aquatic life. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water pollution is usually caused by wastewater released into the water bodies without proper treatment. This can cause aquatic life living in those water bodies to suffer severe consequences. All the species living in the water body are affected, and there is a danger of them becoming extinct. This uncontrolled release can also lead to waterborne diseases. These diseases spread when unclean water is used for drinking, irrigation and other purposes.

Fig: Water pollution

Prevention of water pollution

Water pollution can be prevented by the following measures:

  • Taking appropriate precautions when designing and building infrastructure.
  • Proper management of the infrastructure.
  • Treating water pollution by wastewater treatment plants, sewage water treatment plants, and industrial wastewater treatment plants.
  • The Water (Prevention and Control of Pollution) Act should be updated regularly to meet all the modern wastewater treatment standards and ethical use.
  • Water pollution can also be prevented by controlling the stormwater runoff that occurs after heavy rainfall. It can be done by reducing the velocity and flow of the stormwater.

Fig: Wastewater treatment plant

Soil pollution

Soil pollution refers to the contamination of soil with anomalous concentrations of toxic substances. It is a serious environmental concern since it harbours many health hazards. The toxic substances include plastic, chemical fertilisers, etc. Soil pollution is caused by numerous factors. They include mainly solid wastes, agrochemical wastes. plastic wastes, e-wastes and biomedical wastes.

Fig: Soil pollution

Prevention of soil pollution

The following measures are taken to prevent soil pollution:


It is the degradation of organic wastes by microorganisms in presence of oxygen.

Fig: Compost


It converts solid wastes such as sewage sludge and domestic wastes into compost with the help of earthworms.

GIF: Vermiculture


The wastes are dumped in depressions or trench and covered with dirt everyday in landfilling.

Fig: Landfilling


It involves burning of the unwanted wastes at high temperatures.

Fig: Incineration


In this process a product at the end of its service life is converted into another useful product. Examples include recycling of papers.

Fig: Recycling of papers

Plastic pollution

Plastic pollution refers to the entering of plastic elements in the environment of the Earth that causes damage to its wildlife, the habitat of wildlife or humans. Plastic pollution can be differentiated on the basis of its size. On this basis, plastic particles can be differentiated into microplastics (less than <5mm), mesoplastics (5 – 10 mm in range) and macroplastics (greater than 5 mm). All of them affect the environment in a different manner and cause various ecological problems.

Fig: Plastic pollution

Plastics are easy to manufacture, inexpensive and durable materials. Due to this fact, humans manufacture excessive amounts of plastic every year. All the manufactured plastic later ends up in the ecological system of the Earth in various forms. Plastics do not degrade naturally. They are non-biodegradable substances and usually take thousands of years to degrade. Therefore they end up persisting in the ecological systems for years and cause incalculable damage to them. It is estimated that every year approximately 8.8 million tonnes of plastic make their way into the oceans.

Prevention of plastic pollution

The following measures are taken to reduce plastic pollution:

  • Plastic pollution can be reduced with the help of recycling.
  • Recycling is reusing the waste plastic to make it fit for use once again.
  • Recyclable waste and biodegradable waste should be separated before disposition.

Fig: Segregation of wastes

  • Banning plastic exports into other countries also helps in reducing the spread of plastic across the globe.
  • All supermarkets and shops must stop using plastic bags. This reduces plastic use and forces people to consider and use more biodegradable alternatives to plastic bags. Paper bags and cloth bags are some of the popular alternatives to plastic bags. They are usually more durable than plastic bags and can also be easily used more than one time.

Fig: Alternatives of plastic bags

Noise pollution

A loud, unwanted or unpleasant sound that causes discomfort is called noise. Noise pollution is defined as excessive noise in the environment that disturbs the natural equilibrium. High levels of noise is an invisible danger that poses a health risk. The sound range around and beyond 85 decibels is considered as noise pollution. Even a brief exposure to sound as high as 150dB which is generated during the take off of jet planes and rockets can permanently damage eardrums. The sources of noise pollution are mostly man-made like honking of vehicles, loudspeakers, industrial sites, crowded places, etc.

Fig: Sources of noise pollution

Prevention of noise pollution

The following measures are taken to control the noise pollution:

  • Proper lubrication and maintenance of machines can reduce noise.
  • Installing machines in soundproof chambers.
  • Industries must be kept away from human settlements.
  • Creation of silent zones around residential areas, educational institutions and hospitals.
  • Planting more trees.
  • Restricting the use of loudspeakers and amplifiers to fixed hours of the day.

Strategies to save the environment from pollution

The following strategies can save the environment from pollution:

  • Strictly following the norms of the Environment (Protection) Act.
  • Following 3 R’s - Recycle, Reduce and Reuse.
  • Reducing the use of plastics and use of eco-friendly natural fibres.
  • Promotion of polybend in road construction.
  • Proper segregation and on-site or off-site incineration of biomedical wastes.
  • Environment friendly recycling and treatment of e-wastes.
  • Promoting integrated organic farming.
  • Taking appropriate precautions when designing and building infrastructure.
  • Proper management of the infrastructure.
  • Treating water pollution by wastewater treatment plants, sewage water treatment plants, and industrial wastewater treatment plants.

Practice Problems

1. Any undesirable change in physical, chemical or biological characteristic of air, land, water or soil is called ________________.

(A) biomagnification
(B) population explosion
(C) pollution
(D) eutrophication

Solution: Any undesirable changes including physical, biological or chemical to the environment causing various adverse effects is called pollution. These changes affect characteristics of air, water, land or soil. Hence the correct option is (C).

2. Agents that bring about an undesirable change in our environment are called as ___________.

(A) allergens
(B) mutagens
(C) carcinogens
(D) pollutants

Solution: Pollutants are agents that cause undesirable changes in the environment thus changing the characteristics of land, air, soil, water etc. Examples of pollutants include plastics, pesticides etc. Hence the correct option is (D).

3. The Environment (Protection) Act was passed in _____________.

(A) 1986
(B) 1981
(C) 1974
(D) 1968

Solution: The Environment (Protection) Act is the bill passed by the Government of India in 1986 to control the environment pollution and to take steps for improving the quality of air, soil and water. Hence the correct option is (D).

4. Most harmful types of environmental pollutants are ________________.

(A) human organic wastes
(B) natural nutrients in excess
(C) waste animal feed
(D) non-biodegradable chemicals

Solution: Non-biodegradable chemicals are substances which are not degraded or decomposed by microorganisms. Thus they cause environmental pollution and are the most harmful pollutant.


1. Why is controlling pollution considered important?
Controlling pollution is important because of the following reasons:

  • It saves money.
  • Ethical and aesthetic reasons
  • It reduces the use of toxic substances.
  • It results in the efficient use of raw materials, natural resources, energy and equipment.
  • It improves the health of workers.
  • It improves air quality.
  1. What is meant by the air quality index?

Answer: Air quality index (AQI) is used to check the daily air quality. For example, if we consider the AQI from 0 to 500, then the higher the AQI value, the greater the level of air pollution and the greater the health concern. An AQI value of 50 or below represents good air quality, while an AQI value over 300 represents hazardous air quality.

3. What is the water quality index?
A water quality index is the weighted average of selected ambient concentrations of pollutants usually linked to water quality classes.

4. Write down the major differences between primary and secondary air pollutants?
An air pollutant emitted directly from a source is called a primary air pollutant. Examples include particulates, carbon monoxide etc. A secondary pollutant is not directly emitted but it is formed when other pollutants like primary pollutants react in the atmosphere. Examples include ozone, secondary organic aerosol etc.

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