Air Pollution Definition, Causes, Effect and Control

Atmosphere is a thin protective blanket of air or gases surrounding the earth. Air is an essential element of nature that supports life on earth. The contamination of the atmosphere by harmful chemicals or biological and physical materials is one of the most serious global problems. This problem is termed as Air pollution. It may be caused by natural or man-made activities. But air pollution is majorly caused by human activity. It is injurious to the health of human beings and other living organisms and damages climate and materials. Now it is very important to acknowledge the cause and effect associated with air pollution and suggest appropriate preventive measures to reduce air pollution.

What is Air Pollution?

Air pollution is the undesirable change in the natural characteristics of the atmosphere due to contamination by hazardous substances like chemical, biological and physical pollutants from both human-made and natural sources. Air pollution is the greatest scourge of our era. It affects not only the climate but also public and individual health due to increasing morbidity and mortality. Common air pollutants are carbon monoxide, carbon dioxide, lead, nitrogen oxides, ground-ozone, particulate matter, sulphur oxides etc.

Type of Air Pollutants

Air pollutants’ sources may be natural or anthropogenic. Naturally occurring pollutants are ash, sulphur dioxide, ground-level ozone, salt spray, volcanic and combustible gases, radon released during volcanic eruptions, forest fires, grassland fires etc. Anthropogenic sources of air pollutants are industry, transportation, and other daily activities like cooking, burning etc. There are various aspects to classify the types of air pollutants and they are summarised in the flowchart.

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Primary Air Pollutants

Primary pollutants are directly emitted from different sources and cause air pollution. The major primary pollutants are as follows −

Primary Pollutants Major Sources
Carbon monoxide (CO) Burning of fossil fuels
Sulphur dioxide (SO2) Burning of coal or oil
Nitrogen oxides (NOx) Fires and volcanoes
Particles in suspension (PM) Dust, pollen, ashes, metallic particles,
Volatile organic compounds (VOCs), Hydrocarbons
Heavy metals lead (Pb) and mercury (Hg) Cement or glass production
Chlorofluorocarbons (CFCs) From air conditioning, and perfumes.
Ammonia Pharmaceuticals elements.

Secondary Air Pollutant

Chemical or physical interactions with the primary pollutants or other atmospheric components form secondary pollutants. The major secondary pollutants are as follows −

Secondary Pollutants Sources
Smog Combination of Smoke and Fog
Ground Level Ozone Emissions from industrial facilities.
PANs Oxidised primary pollutants.
Sulfuric acid, Nitric acid Components of acid rain.

Causes of Air Pollution

  • To produce energy for electricity or transportation fossil fuels like coal, oil, gasoline are burnt which mostly cause air pollution.

  • Emission of several particulate matter, NOX, CO2, SO2, and CO from industrial activities can cause pollution.

  • Indoor air pollution occurs due to smoking tobacco, cooking smoke; toxic chemicals from household painting supplies, etc.

  • Ammonia which is formed as a by-product of various agricultural uses and is one of the most dangerous gases in the atmosphere.

Harmful Effects of Air Pollution

If pollutants accumulate in the air in high enough concentrations, harm to our health and environment.

Effects on Health

  • Methylene chloride is found in aerosol products and paint removers, can cause cancer. Benzene, gasoline can cause leukaemia. Gases produced from burnt fossil fuels cause lung cancer.PM and nitrogen cause asthma, other respiratory diseases like COPD.

  • Nitrogen oxide and sulphur dioxide increase the chances of pneumonia,lung inflammation, chest pain, cough, fatigue, shortness of breath, and fever.

  • Ozone and particles in air pollution is the major reason of miscarriages in pregnancy.

Effects on environment

Acid Rain

Precipitation of toxic nitric acid and sulfuric acids with the rain water is called Acid Rain. When fossil fuels are burned, these gases are released and react with the rain water and form nitric acid, sulphuric acid etc.

Acidic deposition in the water body adversely affects aquatic life by reducing biodiversity significantly.Red spruce forests in tropical areas are killed severely due to the acid accumulation.

Acid rain causes discoloration and deterioration of Buildings, monuments and sculptures which are made up of sandstone, limestone, marble and granite. The phenomenon is called stone cancer. It is also found in Taj Mahal and Victoria Memorial.

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Smog (Sunlight + smoke + fog)

Smog is an air pollutant that reduces visibility. Smog is of two types- Sulphurous smog and photochemical smog. Sulphurous smog or London smog develops when sulphur oxides are present in high concentration in the air . Photochemical smog or Los Angeles smog is formed when oxides of nitrogen and at least one volatile organic compound (VOC) are reacted with the presence of sunlight in the atmosphere. Smog enveloped the capital Delhi and other cities of India.

Ozone Depletion

A thin layer of ozone is present in the stratosphere, about 17-26km above the earth's surface. This layer absorbs the UV radiation coming from the sun and protects the earth surface. It is destroyed by some pollutants like CFCs. Then the UV ray enters the earth surface and causes severe effects like DNA mutation. The depletion of ozone is particularly marked over the Antarctica region.

Global Warming and Climate change

When concentration of greenhouse gases is increased, the average temperature also gradually and continuously increases and global warming takes place. In the last three decades global temperature has increased by 6°. Ice caps of polar regions are melted and rising sea level or many coastal areas will be submerged. Global warming damages the environment and as a result climate is also changed, for example the El Nino effect. Precipitation pattern changes also occurred.


  • Implement Afforestation.

  • Reduction of forest fires and smoking.

  • Using public transports and Carpool.

  • Recycle and Reuse paper, plastic, metals and organic materials.

  • Decrease the forest fires and smoking.

  • Give up usage of crackers.

  • Using filters for chimneys.

  • Use the ENERGY STAR equipment for home or office.

  • Switch to renewable energy.

  • The Air Act, 1981 in which air pollution producing fuel burning is prohibited, has to follow.

Control of vehicular pollution

Vehicular pollution is the major problem that degrades the quality of air we breath in. Every day thousands of vehicles are on road emitting harmful air pollutants. It is necessary that we reduce the use of vehicles and switch to eco-friendly modes of transport. Some of these steps are listed below −.

  • Using alternative fuels.

  • Using public transit instead of private vehicles.

  • Using unleaded petrol.

  • Generating public awareness.

Plantation of trees

The total forests of the world absorb the maximum of global emissions every year naturally. Plants are called the “lungs” of an ecosystem, they absorb carbon dioxide and release oxygen. Trees can effectively remove the particulate matter (PM). Conifers like pines and cypresses also work as natural filter. Trees can soak up odours and air pollutants and then filter particulates by trapping them with the help of stomata and bark. So, reforestation is a significant method to reduce air pollution.


Air pollution is detrimental to all living beings and the planet as a whole. Primary pollutants and secondary pollutants are the two major classes of air pollutants. Cancer, cardiovascular disease, respiratory diseases and disorder, diabetes mellitus, obesity, reproductive disorders, neurological, and immunological disorders can be caused by air pollution. Entire ecosystems and the members of it can suffer from air pollution. Plantation & reforestation is the major contributory factor of air pollution. More use of fossil fuel alternatives like CNG, LPG, solar energy, battery operated electrical vehicles (EV’s) can help in reducing the air pollution.


Q1. What is a scrubber?

Ans. Scrubber is a device that contains an ionized liquid that traps any particulate matter or other similar pollutants present in the air and cleans the air to prevent pollution.

Q2. What are alternative fuels?

Ans. Alternative fuels are some substances that can be used instead of conventional fuels like petrol, diesel. etc.Examples of alternative fuels include CNG, hydrogen, etc.These do not cause air pollution and are non-conventional.

Q3. How can we reduce air pollution at home?

Ans. Air polution at home can be reduced by planting indoor plants, keeping proper ventilation in rooms, avoid smoke or grill in the kitchen, etc.


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