What are the Main Sources of Air Pollution

Main Sources of Air Pollution

The air around us is a mixture of many gases and dust particles. The percentages of the various gases present in air are

  • Nitrogen (78.08%)
  • Oxygen (20.95%)
  • Other gases (0.97%)

Natural processes and, to a larger extent, human activities, are responsible for the release of various chemicals into the air. The presence of chemicals in the air in quantities harmful to human health and the environment is known as air pollution. Common air pollutants and their main sources are discussed below.

An undesirable change in the physical, chemical or biological characteristics of the air making it harmful for the living organisms (including man) is termed air pollution. The addition of substances in the environment in quantities that are harmful to living beings is called pollution. Air is getting polluted day by day because of various human activities. Burning of fuels like coal and petroleum, excessive burning of fuels like wood, smoke and harmful gases released from industries, smoke released by vehicles and machines releasing gases are the major causes of air pollution. These gases spread and mix in the air and spoil the quality of air, thereby making it impure.

Common pollutants of air are particulate matter and gaseous pollutants.

  • Particulate matter is also called suspended particulate matter (SPM) because it remains suspended in air for a reasonable period of time. Common examples of SPM are dust, soot (unburnt, carbon, particles), smoke, flyash etc. Particulate matter consists of tiny particles suspended in air. Volcanic eruptions, dust storms, burning of fossil fuels in thermal plants, and forest fires are some-of the natural sources of particulate matter. It is also present in the exhaust fumes of automobiles and power plants as soot, flyash, and lead particles.

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  • Gaseous pollutants include carbon monoxide, excess of carbon dioxide, sulphur dioxide, oxides of nitrogen, hydrocarbons, chlorofluorocarbons (CFCs), hydrogen sulphide, methane and ammonia. Besides, asbestos dust, stone dust, cement dust, pollen grains of plants, radioactive rays etc. are other common air pollutants. Chlorofluorocarbons (CFCs) or freons are commonly used as coolants in refrigerators and air conditioners and as propellants in aerosol spray cans. CFCs are also used in home insulation, plastic foam, and throwaway metallic cans. Burning of fossil fuels like coal and petroleum in thermal power plants and automobiles releases oxides of sulphur and nitrogen into the air. Burning of carbon-rich fuels like firewood, coal, and petroleum releases carbon dioxide and carbon monoxide into the atmosphere.

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What are the Problems with the Use of Fossil Fuels

What are the Problems with the Use of Fossil Fuels

Limitations of Fossil Fuels

Scientists at Sandia National Laboratories, New Mexico, have succeeded in producing fuels like petrol and methanol using sunlight and carbon dioxide.
The two main limitations of fossil fuels are their limited availability in nature and the air pollution caused due to their use.

  1. Limited availability: Fossil fuels take millions of years to form. If we run out of the existing stock of these fuels, we will not get more until natural processes have regenerated them.
  2. Air pollution: Use of fossil fuels adds many undesirable substances, called pollutants, in the atmosphere. These pollutants adversely affect the life of organisms. Pollutants can be in the form of particles or gases.

Some of the main air pollutants and their harmful effects are given below.

  1. Carbon monoxide is a colourless, odourless, and tasteless gas. It is produced by incomplete combustion of fossil fuels. Exposure to carbon monoxide can cause headache and dizziness and can even lead to coma and death.
  2. Carbon dioxide levels in the atmosphere have increased due to the widespread combustion of fossil fuels. This can lead to an increase in the global average temperature, which, in turn, can cause the melting of polar ice caps and glaciers, resulting in a rise in sea level and submerging of coastal areas.
  3. Sulphur dioxide is released when coal is burned. Use of fossil fuels like petrol, diesel, and coal also releases nitrogen oxides. These gases react with oxygen and water vapour present in the air to produce dilute solutions of sulphuric acid and nitric acid, which fall on Earth as acid ram and damage plants, aquatic life, soil, and buildings.
  4. Soot particles are introduced in the air due to the incomplete combustion of wood and fossil fuels like coal and petroleum. These particles can enter our bodies when we breathe and trigger asthma attacks and cause wheezing, coughing, and respiratory irritation.

Biofuels are fuels obtained from renewable biological sources like crops and animal wastes, which can be used to supplement or replace fossil fuels. Ethanol, methanol, and biodiesel are examples of biofuels.

Conservation of Fossil Fuels

Keeping in mind the limitations of fossil fuels, the need of the hour is to conserve them to the extent possible.
Conservation of fossil fuels can be done by

  • Judicious use of the existing resources.
  • Use of alternate sources of energy like tidal power, wind energy, solar energy, and nuclear energy to meet our fuel and energy needs.

Over Extraction of Fossil Fuels

Over Extraction of Fossil Fuels

Fossil fuels are formed from the buried remains of plants and animals over a period of millions of years. Coal, petroleum, and natural gas are some examples of fossil fuels. These fossil fuels are a major part of the world today and its varied uses have led to their over-extraction. The major consequences of over-extraction of fossil fuels are given below.

  1. Exhaustion of existing reserves: The over-extraction of fossil fuels is slowly depleting the Earth of these resources. An energy crisis in the immediate future is a distinct possibility if the present rate of consumption of fossil fuels is not brought under control.
  2. Air pollution: When coal and petroleum products are burnt as fuel, they give off carbon dioxide, a greenhouse gas that leads to global warming. They also give off pollutants like carbon monoxide* nitrogen oxides, sulphur oxides, particulate matter like mineral ash or fly ash, and unburnt hydrocarbons that pollute the air. Some of these gases combine with water vapour in the air and form droplets that fall to the Earth as weak forms of sulphuric and nitric acid, called acid rain.
  3. Threat to organisms: Coal contains poisonous metals like arsenic and mercury, which are dangerous if released into the environment. Mercury that is released into the air settles in water with time. It then enters the bodies of fish and shellfish and can be harmful to animals and people who eat them.

We cannot completely stop the use of fossil fuels. However, cutting down on their use and shifting to renewable energy sources like solar energy, wind energy, and nuclear energy will help us conserve them as well as safeguard the environment. Some renewable sources of energy are discussed below.

Wind energy has been used since ancient times to move ships, pump water, and grind corn. These days, huge wind turbines are used to drive generators
Over Extraction of Fossil Fuels 1Hydroelectric energy is derived from the water in water bodies like rivers with the help of dams and generators.
Over Extraction of Fossil Fuels 2Nuclear energy is released by the splitting or merging together of the nuclei of atoms. In nuclear power plants, this energy is utilized to produce heat energy, which is used to make steam for driving generators.
Over Extraction of Fossil Fuels 3Solar energy is utilized with the help of solar panels and solar cells. Solar panels convert solar energy into heat and light energy while solar cells convert it to electrical energy.
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