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Bharathi Pradeep
Bharathi Pradeep
Editor at Bharathi covers topics on Competitive exams, How To guides, Current exams, Current Affairs, Study Materials, etc. Follow her on social media using the links below.

A combination of liquid and solid fog and smoke particles is described by the smog. Typically, it appears as a ceiling or suspended layer of yellowish or blackish fog that hangs in the air. It takes place when sunlight-induced reactions between fumes, pollutants, and particles (such as nitrogen and sulfur oxides and volatile organic compounds) result in the formation of ground-level ozone. Air pollution causes smog, which makes it harder to see.

What is Smog?

The term was first used to describe smoky fog in the early 20th century because of its opacity and odour. This sort of observable air pollution is made up of smoke, ozone, nitrogen oxides, sulfur oxides, and other particulates. Because of the volume of traffic, the number of companies, and the combustion of various fuels, dense metropolitan areas are more susceptible to smog.

When contaminants are discharged into the atmosphere, smog develops. Both naturally occurring and human-induced pollutants exist, but the latter is more worrisome because of the quantity they produce when fossil fuels are burned and extracted, which is known to have severe negative impacts on health. Since a significant portion of smog is produced in cities, where a sizable portion of the population resides, the location of smog formation is also a major concern, particularly for human health.

Types of Smog

Photochemical Smog

This type of smog is caused by nitrogen oxides and hydrocarbon vapours, which are released by vehicles and other sources and subsequently undergo photochemical reactions in the lower atmosphere. In the presence of sunshine, nitrogen oxides combine with hydrocarbon vapours to produce the extremely poisonous gas ozone, and some nitrogen dioxide is also produced when nitrogen oxides interact with sunlight.

As a result, the air turns a light brownish colour, visibility is decreased, plants are harmed, eyes are irritated, and breathing difficulties are brought on by the smog. When surface-level ozone concentrations surpass 70 ppb for eight hours or longer, they are deemed harmful; these conditions are rather typical in cities that are prone to photochemical smog.

Sulfurous Smog

It is brought on by the use of sulfur-containing fossil fuels, primarily coal, which raises the level of sulfur oxides in the atmosphere. This kind of smog is made worse by moisture and a significant amount of suspended particulate matter in the air. Reducing smog is another name for this smog, which contains a high concentration of reducing agents.

Causes of Smog

The typical causes of smog include pollutants that cause haze from a variety of sources, including industry, consumer goods, and cars. More than half of the haze in most urban areas is caused by vehicle emissions. Smog is typically brought on by the interactions between weather patterns, heavy traffic, industrial emissions, and other emissions from consumer goods. Paints, sprays, plastic containers, and solvents are examples of consumer goods.

Agriculture Material Burning

Farmers’ practices of burning standing stubble are frequently blamed for the worsening of haze episodes in the agricultural plains of the Indus basin in India after paddy crops have been harvested. It takes place in the late autumn months of October and November. Farmers in that watershed have long favoured using biomass fire (paddy stubble leftover) to clear cropland. Contrarily, smog is more frequently linked to burning agricultural biomass, despite consistent agricultural landholding and productivity. The enormous metropolis of India experiences it each winter. The burning of agricultural waste in Punjab and Haryana is the main cause of the buildup of haze and smog in Delhi.

Vehicle and Industrial Emissions

We mostly observe photochemical smog. When sunlight interacts with nitrogen oxides and at least one volatile organic compound (VOC) in the atmosphere, photochemical smog is created. Automobile exhaust, coal-fired power plants, and industrial pollutants all produce nitrogen oxides.

Gasoline, paints, and a variety of cleaning solvents all release VOCs. These substances combine to create smog-causing airborne particles and ground-level ozone when exposed to sunlight. The industrial process uses numerous fossil fuels and resources that must be mined from nature to produce different materials and coals.

As a result, the industries also contribute to the release of hazardous gases and fumes into the atmosphere, which in turn causes smog to develop. In the Indian context, the extreme absence of exhaust measures, the highly varied character of cars, and low fuel quality are some of the key contributors to excessive traffic emissions.

Fueling with Coal

Coal is a plentiful fuel source that may be produced at a low cost and converted into useful energy. However, the ecology is impacted by the production and use of coal.

Sulfur dioxide (SO2), which causes acid rain and respiratory ailments, and nitrogen oxides (NOx), which cause smog and respiratory illnesses, are two of the main pollutants that come from burning coal. Particulates cause respiratory ailments, lung disease, pollution, haze, and other environmental problems. High levels of suspended particulate matter in the air and moisture exacerbate the effects. Significant amounts of smoke are produced when burning coal, which causes smoky environments.

Production of Waste in Excess

Waste from construction and demolition projects is a significant contributor to air pollution in India. These buildings have the potential to be the main sources of GHG emissions even after the construction phase.

Today’s growing interest in green building technology and the use of green infrastructure and building materials could significantly address this problem, protecting our biodiversity and upholding improved air quality. We produce a lot of waste as a result of our excessive consumption. Many of the waste’s components are burned to be disposed of, which releases dangerous gases into the atmosphere that later turn into smog.


In addition to the metals and fuses that make up the firework themselves, colourants, explosives, and other components all contribute significantly to the pollution produced by fireworks. The air is filled with tiny metal-filled particles, organic and inorganic species, and toxic gases including sulfur dioxide, nitrogen dioxide, carbon monoxide, and nitrous acid as a result of the fireworks’ exhilarating bursts that cause smog.

Waste Management and Burning Biomass

About 80% of the municipal solid waste (MSW) that is generated in India is still dumped in open landfills and dumping yards, which causes several GHG emissions in addition to problems with bad odour and poor water quality in the adjacent communities. Inefficient MSW treatment and biomass burning are to blame for the air pollution in metropolitan areas.

The burning of trash and other MSW produces about 5300 tonnes of PM10 and 7550 tonnes of PM2.5 in Delhi alone per year. The main contaminant generated from landfills and wastewater treatment facilities is methane (CH4). Another by-product that is generated during the composting process is ammonia (NH3).

How is Smog Formed?

The term smog is used to describe air pollution that develops when sunlight interacts with specific substances in the environment. Ozone is one of the main elements of photochemical smog. Ozone on the ground is damaging to human health, whereas ozone in the stratosphere shields the earth from dangerous UV radiation. When sunlight interacts with nitrogen oxide-containing vehicle emissions (mainly from exhaust) and volatile organic compounds (from paints, solvents, and fuel evaporation), ground-level ozone is created. Because of this, some of the sunniest cities are also among the dirtiest.

Why is Smog Harmful?

Smog irritates our airways when we breathe it in, raising our chance of developing serious lung and heart conditions. Because of these health dangers, many cities keep an eye on smog levels. The eyes and throat may burn on a day with a high ozone alert and may cough and wheeze as well. While the young and the elderly are especially vulnerable to the impacts of pollution, anyone who is exposed to it for either a short or lengthy period of time might have negative health effects. Shortness of breath, coughing, wheezing, bronchitis, pneumonia, inflammation of the lungs’ tissues, heart attacks, lung cancer, an increase in asthmatic symptoms, exhaustion, heart palpitations, and even early ageing of the lungs, and mortality are all difficulties.

Effects of Smog

Smog Effects on Humans

Being exposed to air pollution has a variety of negative consequences on people’s health. Illnesses like pneumonia or bronchitis are examples of short-term consequences, which are transient. They also consist of discomforts like rashes on the nose, throat, eyes, or skin. Headaches, vertigo, and nausea can all be brought on by air pollution. Air pollution can include offensive odours produced by manufacturing facilities, waste, or sewage systems. While less harmful, these smells are nevertheless unpleasant.

Heart disease, lung cancer, and respiratory conditions like emphysema are some of the long-term health repercussions of air pollution. Long-term exposure to air pollution can also damage a person’s kidneys, liver, brain, nerves, and other organs. Some scientists believe that air pollution is the root cause of birth anomalies. Varied types of air pollution have different effects on people.

Children and older adults with weakened immune systems are frequently more sensitive to pollutants. Exposure to air pollution can exacerbate diseases like asthma, heart disease, and lung conditions. Pollutant quantity, kind, and duration of exposure are additional important considerations.

Smog Effects on the Environment

The consequences of air pollution can affect entire ecosystems, just like they can on people, animals, and plants. Similar to smog, haze is an obvious form of air pollution that makes colours and forms difficult to see. Hazy air pollution can even mute noises. Particles from air pollution eventually land on Earth.

The soil and water surface can be directly harmed by air pollution. This may result in crop death or decreased output. Young trees and other plants can also die from it. Acid rain can be produced when airborne sulfur dioxide and nitrogen oxide particles combine with atmospheric water and oxygen.

Vehicles and coal-fired power plants are the main sources of these air pollutants. When acid rain hits the Earth, it harms crops, erodes water quality in rivers, lakes, and streams, damages plants by altering the composition of the soil, and can hasten the deterioration of structures such as monuments and buildings. Animals are not exempt from the negative effects of air pollution on human health. Air pollution is thought to be responsible for diseases, birth defects, and lower fertility rates.

Smog  Effects on Global Warming

Natural and man-made air pollution are the main contributors to the environmental phenomenon known as global warming. It alludes to global increases in both air and ocean temperatures. An increase in greenhouse gases in the atmosphere is at least largely to blame for this temperature rise. Greenhouse gases keep the Earth’s atmosphere warm.

The heat from the Earth often escapes more into space. The most significant contribution to global warming has come from the greenhouse gas carbon dioxide. Burning fossil fuels releases carbon dioxide into the atmosphere (coal, gasoline, and natural gas). Fossil fuels are now heavily relied upon by humans to run companies, heat houses, and power cars and planes. Doing these actions releases carbon dioxide into the atmosphere. Methane, nitrous oxide, and fluorinated gases are additional greenhouse gases that are released by both natural and man-made sources. Coal-fired power stations and agricultural operations emit a lot of methane.

Common sources of nitrous oxide emissions include industrial facilities, agriculture, and the combustion of fossil fuels in motor vehicles. Industry emits fluorinated gases like hydrofluorocarbons. Chlorofluorocarbons and other gases are frequently substituted with fluorinated gases. Because they damage the ozone layer, CFCs have been banned in many places.

How Smog can be Controlled

  • Conserve energy everywhere you are—at work, at home, etc.
  • When purchasing equipment for your home or office, look for the ENERGY STAR label.
  • When possible, carpool, take the bus, bike, or walk there.
  • For effective vapour recovery, follow the directions for refuelling with gasoline. Be cautious not to spill any fuel, and make sure the gas cap is properly tightened.
  • Where available, think about buying portable fuel containers marked “spill-proof.”
  • Keep the engines of your car, boat, and other vehicles tuned.
  • Make sure your tyres are filled appropriately.
  • Whenever possible, use paints and cleaning supplies that are safe for the environment.
  • Compost or mulch your yard debris.
  • Think about switching to gas logs from wood.


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Bharathi Pradeep
Bharathi Pradeep
Editor at Bharathi covers topics on Competitive exams, How To guides, Current exams, Current Affairs, Study Materials, etc. Follow her on social media using the links below.

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