Air Pollution – Types, Effects, Cause, and Control

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Air pollution

When certain chemicals and particles accumulate in the atmosphere to such high levels that they can impair human health, resulting in breathing and respiratory issues, even leading to early death, as well as harming the environment around us, this is known as air pollution.

“Air pollution” is defined as the release of pollutants into the atmosphere that are hazardous to both human health and the environment.

Pollutants are gases and particles that are typically produced by human activity, such as burning fossil fuels like coal, oil, gasoline, or diesel, but they can also be produced naturally by events like volcanic eruptions and forest fires. Air pollutants can be either in solid form, liquid droplets or gases.

Air Pollution
Air Pollution

Types of Air pollution

Primary pollutant

Primary pollutants are those that are released as a direct result of human or natural activity.

As an example, consider CO2, SO2, NOx, particulate matter, and hydrocarbons.

Some of the major primary pollutants are:

Carbon monoxide (CO)

The gas carbon monoxide (CO) is extremely deadly and colorless with no odor. It results from incomplete combustion processes that use carbon-based energy sources, such as burning gasoline, coal, or wood. Vehicles are one of the main generators of carbon monoxide, particularly when they are traveling slowly or while the engine is not running. Carbon monoxide is harmful to people because, after being inhaled, it competes with oxygen by binding to hemoglobin in red blood cells and depriving essential organs including the heart, brain, and nervous system tissues of oxygen, which impairs their ability to function.

The CO pollution can be prevented by following methods:

  • Development of new types of engines to replace combustion engine.
  • Development of substitute fuels for gasoline which produce the low concentration of pollutants upon combustion.
  • Modification of internal combustion engines for reducing the amount of pollutants formed during fuel combustion.

Nitrogen dioxide (NO2)

A category of gases known as nitrogen oxides (NOx) are composed of various ratios of oxygen and nitrogen molecules. Nitrogen dioxide (NO2), a reddish-brown gas with a disagreeable odor and the most prevalent nitrogen oxide, is toxic at high doses. They can also be created naturally by lightning strikes and are created when fossil fuels are burned at high temperatures. In cities, exhaust emissions are primarily responsible for nitrogen dioxide emissions. As it irritates the lungs’ lining and lowers resistance to lung infections, it may increase the incidence of respiratory issues. As a result, issues including wheezing, colds, the flu, coughing, and bronchitis may emerge. Some of the controlling measures of it are listed below:

  • Utilizing fuels with low nitrogen content is one method of reducing NOx emissions.
  • Alter the combustion process to produce less NOx.
  • The use of catalytic converters for control of automotive emission provides for removal of NOx.
  • NOx can be eliminated using flue gas treatment methods like selective catalytic reduction (SCR) procedures.

Sulphur compounds

Sulfur and oxygen molecules combine to form a family of substances known as sulfur oxides (SOx). The most prevalent form of sulfur oxide is sulfur dioxide (SO2), an invisible gas with a smell similar to burned matches. They are created when sulfur-containing fuels, such as coal and oil, are burned for energy production and industrial processes, together with metal-containing ores. Additionally, it comes from natural sources like hot springs and active volcanoes. Inhaling sulphur dioxide into the body might make breathing harder. Additionally poisonous to plants, it can result in acid rain when it interacts with atmospheric moisture.

Since it is one of the main sources of air pollution, its control is necessary. Here are some controlling measures:

  • Burning low-sulfur fuel, such as  low-sulfur oil, natural gas, or low-sulfur coal, is an efficient way to reduce SOx emissions since sulfur emissions are proportional to the sulfur content of the fuel.
  • Substitution of other fuel energy for fuel combustion.
  • With the use of a scrubber, a tool that collects gaseous contaminants.

Ammonia (NH3)

A highly soluble, colorless gas with a potently unpleasant scent is ammonia (NH3). It is typically given out by the usage of fertilizers, vehicle exhaust, and animal feces. Agriculture, which includes extensive animal and crop husbandry, is the main source of ammonia release. Ammonia and ammonium pollution contribute to nitrogen enrichment effects when they fall to the ground, causing some plants, notably trees, to develop more quickly. The heating processes in a cowshed can be managed to provide better opportunities to reduce ammonia emissions.


Particulates, also known as particulate matter (PM), are microscopic bits of solid or liquid in the air that can include hundreds of different substances, such as metal compounds, sulfur, nitrogen, and carbon. They occur in a variety of sizes and forms and are found everywhere, including industrial sites, unpaved roads, industrial sites, and building sites. Some may be seen with the unaided eye, while others require the use of strong microscopes.

Secondary Pollutant

When primary pollutants interact with one another in the atmosphere, secondary pollutants are generated. Some of the major secondary pollutants are:

Nutrient enrichment

Pollutants with nitrogen content, including NOx and NHx, are considered nutrient enrichment chemicals. When nitrogen oxides and ammonia react with water and other chemicals in the atmosphere to generate wet or dry particles that fall to the ground, they can be carried over long distances. Because of the nutrient enrichment brought on by these pollutants, there is more nitrogen available for plant growth, which might modify the ecosystem and lead to the extinction of significant plant species. When there is more nitrogen available than what plants need, the surplus is leached off, raising the levels in our lochs and rivers.

Ground level ozone

Ozone (O3) at ground level is a colorless gas that contributes significantly to atmospheric smog. It is created when sunlight-induced chemical interactions between nitrogen oxides (NOx) and volatile organic compounds occur. Particularly in people with respiratory and heart conditions, ozone can irritate the respiratory tract and eyes, producing chest tightness, coughing, and wheezing. Because it inhibits plant development and production, particularly that of food crops, ozone is also a harmful air pollutant to plants. Ozone (O3) has an impact on both structures and building components.

Acid rain

Nitrogen and sulfur dioxide (SO2) combine to create acid rain. dioxide (NO2), water, and oxygen interact in the atmosphere. and other substances to create a variety of acidic compounds. The substances can harm plants when they land on the ground, including trees. Additionally, they have the potential to make our soils, rivers, lochs, and streams more acidic, which could have an impact on the sensitive ecosystems that dwell there. Additionally, the degradation of priceless structures, statues, and sculptures is accelerated by acid rain. Sulfur dioxide and nitrogen dioxide, two pollutants that contribute to acid rain, can be harmful to human health. These gases can interact with one another in the atmosphere to produce tiny sulfate and nitrate water droplets, which can irritate the airways and eyes.

Causes of Air Pollution

The following are significant reasons for air pollution:

Fossil Fuel Burning: Fossil fuel combustion releases a lot of sulfur dioxide into the atmosphere. Air pollution is also caused by carbon monoxide, which is released when fossil fuels are burned inefficiently.

Automobiles: Vehicle emissions, including those from trucks, cars, buses, and jeeps, pollute the environment. These are the main producers of greenhouse gases, and they also make people sick.

Fertilizers and Pesticides: One of the most dangerous gases released during agricultural operations is ammonia. Insecticides, pesticides, and fertilizers contaminate the atmosphere by emitting dangerous chemicals.

Industries and Factories: The primary source of carbon monoxide, organic compounds, hydrocarbons, and chemicals is industry and manufacturing. These are dispersed into the atmosphere, lowering the quality of it.

Mining Operations: Large pieces of machinery are used in the mining process to extract the minerals from below the earth. In addition to polluting the air, the dust and chemicals released during the process also harm the workers’ and the residents’ health.

Homegrown Sources: The toxic chemicals in paints and household cleaning supplies are released into the air. The fresh paint on the walls gives off the scent of the chemicals used to make the paints. In addition to polluting the air, it also has an impact on breathing.

Impacts of Air Pollution

The World Health Organization (WHO) and other international agencies recognize air pollution as a major threat to human health. Depending on the type of pollutant, different effects of air pollution can be experienced. However, the impacts of air pollution could include anything from:

  • Cardiovascular problems and respiratory illnesses are more likely to develop.
  • The risks of skin diseases are higher.
  • There may be a rise in cancer risk.
  • Climate change
  • rain that is acidic
  • Depletion of ozone
  • Risks to wildlife

Prevention of Air Pollution

The following actions should be taken to reduce air pollution:

Conserving energy: To create electricity, a lot of fossil fuels are burned. Therefore, remember to turn off any electrical devices that are not in use. Consequently, you can protect the environment on a personal level. Utilizing energy-saving technology, such as CFLs, also significantly reduces pollution.

Using renewable energy sources: Utilizing geothermal, solar, and wind energy helps to reduce air pollution more significantly. As a step toward a cleaner environment, many nations, including India, have implemented the use of these resources.

Modeling of air quality: The levels of various pollutants in the atmosphere can be simulated using numerical models, either on a global scale using tools like GCMs (general circulation models coupled with a pollution module) or CTMs (Chemical transport models). 

Monitoring: Spatiotemporal air quality monitoring may be required to assess the effects of interventions, improve air quality, and subsequently the public’s health and safety.


  • Brimblecombe, Peter. “History of air pollution.” in Composition, Chemistry and Climate of the Atmosphere (Van Nostrand Reinhold (1995)
  • Williams, Ian. Environmental Chemistry, A Modular Approach. Wiley. 2001. ISBN0-471-48942-5
  • vanLoon, Gary W.; Duffy, Stephen J. (2000). Environmental Chemistry. Oxford: Oxford. pp. 7. ISBN 0-19-856440-6.
  • Harrison, R.M (edited by). Understanding Our Environment, An Introduction to Environmental Chemistry and Pollution, Third Edition. Royal Society of Chemistry. 1999. ISBN 0-85404-584-8

About Author

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Jyoti Bashyal

Jyoti Bashyal, a graduate of the Central Department of Chemistry, is an avid explorer of the molecular realm. Fueled by her fascination with chemical reactions and natural compounds, she navigates her field's complexities with precision and passion. Outside the lab, Jyoti is dedicated to making science accessible to all. She aspires to deepen audiences' understanding of the wonders of various scientific subjects and their impact on the world by sharing them with a wide range of readers through her writing.

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