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Introduction To Air Pollution

by | Mar 18, 2022 | Air Pollution, Pollution

History of Air Pollution 

The introduction to Air Pollution began dating back to the discovery of fire. However, it became impactful after human exposure to the chemical species created by biomass burning like wood and vegetation combustion in poorly ventilated areas where concentrations might reach levels hazardous to human health.

The Industrial Revolution in the nineteenth century resulted in enormous volumes of air pollutants being released into the atmosphere. This happened due to the high burning of a range of fossil fuels (coal, oil, and gas). During the nineteenth and twentieth centuries, air pollution in London was exceptionally severe. Introduction to air pollution must mention the most well-documented event of London air pollution happened in the winter of 1952.

Combustion smoke mixed with London fog creates “smog,” invented by Harold Antoine des Vux. He was a member of the Coal Smoke Abatement Society during an American Medical Association convention in London in the early twentieth century. Several thousand people died as a result of the stagnant atmosphere during the 1952 incident. That had high quantities of sulfur dioxide (SO2), oxides of nitrogen (NOx), and air particles (particularly sulfate).

A new sort of air pollution arose in the Los Angeles basin in California during the 1950s. Secondary pollutants such as ozone, oxygenated organic compounds (e.g., acrolein), and fine particles were formed as a result of the use of large cars to move around an area characterized by widely urban planning. Those pollutants got combined with industries (power plants, refineries, port activities, etc.) located on the Pacific coast. Chemical processes in the atmosphere cause this form of pollution.

The degradation of forests in Europe and North America throughout the 1970s implied the presence of a different sort of pollution. Acidic species such as sulfuric acid (H2SO4) and nitric acid (HNO3) deposited in the atmosphere dramatically changed the chemical balance of soils and surface waters. As a result, nutrients were mobilized and washed away, while poisonous metals were made available to roots and terrestrial and aquatic plants and wildlife. The burden of those acidic species was related in large part to rain occurrences, this sort of pollution was dubbed “acid rain.”

Diesel particles have just been classified as carcinogenic to humans by the World Health Organization’s International Agency for Research on Cancer (IARC). Later, the International Agency for Research on Cancer classified air pollution as carcinogenic to people as a whole.

This brief historical overview emphasizes that the term “air pollution” refers to a wide range of contaminants and adverse health and environmental consequences. Air pollution also happens on a range of geographical and temporal dimensions.

Air pollution

Meteorology and Transport of Air Pollution 

Air movements influence the Meteorology and transport of air pollutants. Any analysis of air pollution must also involve looking at the weather patterns in the area (meteorology). If the air is quiet and pollutants are unable to disperse, the concentration of pollutants will rise. Turbulent and robust winds tend to remove pollutants fast. This results in reduced pollutant concentrations.

Wind data records are usually used to record the overall direction and region of emissions where high pollution levels appear at a monitoring station. Identifying the sources of air pollution allows for making a plan to decrease the negative effects on air quality.

The anemometer’s wind vane also measures the direction of airflow, which is recorded on a wind rose. A wind rose is a figure that shows the relative frequency with which wind blows in different directions around the compass. Seasonal wind patterns and local variations by time of day can be documented in detail. The diurnal wind rises to track basic atmospheric weather patterns on a monthly seasonal basis.

 Major variations in wind direction by time of day are recorded by the lapse (daytime) and inversion (nighttime) wind roses. This method of plotting daily and seasonal air pollution concentrations is beneficial for identifying pollution sources and assessing their influence on air quality.

A wind rose may be produced at any time of day, and it can depict the direction of the wind for any month or season. Pollutant and odour dispersal from point or area sources may also be tracked or predicted using wind roses. Pollution rose may also be made to show the frequency of pollutant levels recorded or expected as a function of wind direction.

Through the mechanisms mentioned above, climate change may influence the large-scale circulation of the atmosphere and hence on the intercontinental movement of pollutants. Climate change will alter the air chemical environment and pollutant durations and impact meteorological transport systems.

The Hadley circulation dictates where the Intertropical Convergence Zone (ITCZ) is located in the tropics. Deep convection and mean upwelling is linked to the Hadley circulation, which influences pollution dispersion through controlling transport mechanisms.

Global Implication of Air Pollution 

While most pollution is “regional” – or national – in origin, necessitating local remedies, air pollution may also be a transboundary issue, necessitating global or regional consensus on steps to address it. People, wildlife, and the ecosystem are all harmed by global warming, pollution, and climate change. 

A layer of pollution traps heat worldwide, causing global warming, commonly known as climate change.

When sulfur dioxide and oxides of nitrogen are discharged into the air, a chemical reaction occurs, resulting in acid rain. These harmful compounds may arise to great heights in the sky. These compounds combine and react with water, oxygen, and other molecules resulting in acidic pollutants. These acidic molecules come down on the Earth’s surface by rain, referred to as acid rain. Sulfur dioxide and nitrogen oxides are particularly easy to dissolve in water and may be transported a long distance by the wind. As a result, the two compounds can travel vast distances and become part of the rain, sleet, snow, and fog that we encounter on some days.

When nitrogen oxides and volatile organic compounds (VOCs) combine with sunlight, it creates photochemical smog, resulting in a brown cloud over cities. It happens more frequently in the summer since that is when we get the most sunshine.

Smog reduction refers to instances of air pollution marked by high levels of sulfur dioxide and smoke (or particulate aerosols). Reducing smog is frequently referred to as London-type smog because of its historical occurrence  in that city during the 1950s,

The continuous weakening of the Earth’s ozone layer in the upper atmosphere caused by the discharge of chemical substances with gaseous chlorine or bromine from industries and other human activities is called ozone depletion. The thinning of this layer is mainly noticeable and affecting over Antarctica and the polar regions. This resulted in huge biodiversity loss in these areas. Ozone depletion has become a severe environmental issue because it increases the amount of direct ultraviolet (UV) radiation reaching the Earth’s surface, which has many harmful effects such as skin cancer, genetic and immune system damage, and cataracts. 

Effects of Air Pollutants

People who are very much exposed to air pollution. They suffer from a variety of health problems. Short-term impacts and long-term effects are two types of effects.

Lung infections such as bronchitis, pneumonia, and occupational respiratory disorders are examples of short-term consequences. They can also irritate multiple organs like eyes or skin. Headaches, drowsiness, and nausea are all symptoms of air pollution. Air pollution includes unpleasant odours produced by industry, waste, and sewer systems. These scents might not feel bad, but they are unpleasant and dangerous.

Air pollution’s long-term impacts can continue for years or even a lifetime. They have the potential to kill a person. Cardiovascular diseases, cancer, and respiratory disorders like emphysema are all long-term health repercussions of air pollution. 

Air pollution even harms people’s brains, nerves, kidneys, livers, and other organs over time. Doctors studied that air pollution is causing birth abnormalities. Every year, almost 2.5 million people die as a result of the consequences of outdoor or indoor air pollution throughout the world.

Air pollution is becoming dangerous. It has the potential to seriously harm entire ecosystems, just as it does to people. It also harms animals and plants. Smog and haze are both observable forms of air pollution that distort patterns and colours. Hazy air pollution muffles sound.

Particles of air pollution ultimately fall on Earth. The surface of water bodies and soil can be directly contaminated by air pollution. This can harm or diminish the production of crops. It has the potential to destroy young trees and vegetation.

When sulfur dioxide and nitrogen oxide airborne particles combine with water and oxygen in the atmosphere, acid rain can result. Power stations fueled by coal and automobiles are some of the primary and significant sources of harmful pollutants in the air. 

Acid rain harms plants by altering soil composition; it impairs water quality in rivers, lakes, and streams; it harms crops, and it can cause buildings and monuments to deteriorate. Animals, like people, are susceptible to the health impacts of air pollution. 

Global warming is both a natural and manmade environmental phenomenon. This phenomenon is poorly induced by air pollution and linked to the excessive increase in air and ocean temperatures. An increase in the concentration of greenhouse gases in the atmosphere is causing the temperature to rise annually. In the Earth’s atmosphere, greenhouse gases trap heat energy, which is essential for the survival of life. Nevertheless, less heat is escaping from the Earth, making it warmer than needed.

The Great Smog of 1952, also known as the London Smog of 1952, was a four-day event that affected 100,000 people and killed as many as 12,000 people. The chilly weather in London, England, in December 1952 prompted inhabitants to use extra coal to stay warm. A heavy fog that descended over the city trapped smoke and other impurities. The dirty fog had thickened to the point that individuals could barely see a few meters ahead of them.

The Great Smog of 1952, also known as the London Smog of 1952, was a four-day event that affected 100,000 people and killed as many as 12,000 people. The chilly weather in London, England, in December 1952 prompted inhabitants to use extra coal to stay warm. A heavy fog that descended over the city trapped smoke and other impurities. The dirty fog had thickened to the point that individuals could barely see a few meters ahead of them.

Air Quality Index 

The Air Quality Index (AQI) is a daily reporting measure for air quality. It is a metric for how air pollution impacts one’s health over a short period. The AQI’s main objective is to inform individuals aware of how bad the local air is. Bad air quality affects their health. The Environmental Protection Agency (EPA) measures the AQI for five primary and harmful air pollutants. National air quality guidelines have also been set to protect public health.

The higher the AQI number, the more polluted the air is and the larger the health risks. Over the last three decades, the idea of AQI has become broadly accepted in many affluent nations. Air quality information is disseminated in real-time via AQI.

To report air quality, various countries have implemented point systems. The United States, for example, employs a 500-point scale, with a score of 0 to 50 deemed satisfactory. A rating of 301 to 500 is deemed hazardous. India, too, uses the 500-point scale. 

Every day, sensors record the biggest contaminants’ concentrations. EPA-developed standard equations are used to evaluate these raw values into a distinct AQI value for each pollutant (ground-level ozone, particulate pollution, carbon monoxide, and sulfur dioxide). The AQI value for that day is determined by the highest of these AQI readings.

Categories of the Air Quality Index:

  • Good (between 0 and 50) – Minimal Impact
  • Acceptable (51–100) – Sensitive persons may experience modest breathing issues.
  • Moderately Polluted (101–200) – May cause breathing difficulties in persons with lung diseases such as asthma and discomfort in people with heart disease, children, and the elderly.
  • Poor (201–300) – May cause breathing issues in persons exposed for an extended period and discomfort in people who have heart disease.
  • Very Poor (301–400) – May cause respiratory illness in exposed persons for a long period. People with lung and heart problems may experience a more potent effect.
  • Severe (401-500) – May cause respiratory problems in healthy persons and major health problems in people who have lung or heart illness. Difficulties might arise even when engaging in mild physical exercise.

It is important to be aware of everyday levels of air pollution, specifically for people who suffer from conditions related to exposure to air pollution.

Objectives of AQI:

  • It also helps in the detection of incorrect standards and insufficient monitoring programs.
  • The Air Quality Index (AQI) aids in the analysis of the difference in air quality (improvement or degradation).
  • The Air Quality Index (AQI) provides knowledge to the public about environmental conditions. It is extremely beneficial for persons who have ailments that are exacerbated or caused by air pollution.  



  • The author has done a master's in Environmental science and is currently working as chief Environmental Advisor with New Delhi State Government.


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