Essay on Causes of Air Pollution

This Essay on causes of air pollution discusses 4 leading factors of air pollution. Air pollution is a major environmental issue caused by the release of harmful substances into the atmosphere. These pollutants originate from various human activities, such as industrial processes, vehicle emissions, and the burning of fossil fuels. Natural causes like wildfires and volcanic eruptions also contribute to air pollution.

Acid rain Causing Air Pollution

Acid rain, which nowadays is termed as acid deposition, was discovered by Angus Smith in the United Kingdom in the mid seventeenth century but this phenomenon gained importance as a serious environmental problem in the 1950s. Initially it referred to the precipitation which was more acidic than natural rain. Due to the presence of CO₂ in the atmosphere the natural rain itself forms carbonic acid.

CO₂ (gas) + H₂O (aq) —————————————–> H₂CO₃ (aq)

The pH of unpolluted rain water should be 5.6. The rainwater that has pH less than 5 is considered truly acidic. In the atmosphere SO₂ and NO_x are transformed by reactions with Oxygen and water into H₂SO₄ and HNO₃ respectively. These acids get mixed with rain. The acid deposition includes both wet (rain, snow, drow) and dry acidic deposition.

Acidification of the soil and rocks can leach metals like aluminum, mercury, lead and calcium and discharge them into water bodies. These heavy metals are accumulated in the fish and such organic food is hazardous to human health. Acidification of soil can also leach nutrients thus affecting the crops in an adverse manner. It also damages building materials such as steel, paint, plastic, cement, masonry, work and sculptural materials especially marble and limestone.

Smog Causing Air Pollution

The term smog is a mix of smoke and fog. If it has a high concentration of SO2, it is chemically decreased, which is known as lowering smog. Coal combustion is the primary cause of lowering smog.

Photochemical smog, also known as oxidising smog, is made up of high concentrations of oxidants such as ozone. It is a yellow-brown haze caused by the presence of water droplets and chemical reactions of pollutants in the air. It has a foul odour due to its gaseous constituents. The primary reactants of photochemical smog are NO and unburned hydrocarbons.

For smog to form adequate levels of NO, hydrocarbons and volatile organic chemicals must be present in the air; sunshine is required for quick chemical reactions to occur; and air movement should be kept to a minimum to avoid disturbing the reactants.

The overall product is a mixture of H₂O₂, HNO₃, peroxyacetyl Nitrate (PAN) and ozone. PAN is an eye irritant and is toxic to plant life.

Ozone Causing Air Pollution

Ozone, O₃, is present in small concentrations throughout the atmosphere. The amount of ozone in the atmosphere is expressed in Dobson units (DU). The normal amount of overhead ozone is about 350 DU.

The Ozone layer, which is 25 to 28 kilometres high in the stratosphere, surrounds the earth and filters out the majority of the dangerous ultraviolet (UV) radiation in sunlight before it enters the atmosphere. As a result, if the ozone layer is significantly reduced, life on Earth will be severely imperilled. Most tropical locations produce ozone by photochemical reactions of oxygen, which is then transferred to polar regions.

Ground-level ozone acts as a pollutant and causes various health problems, i.e., damages eyes and aggravates asthma, decreases the elasticity of lung tissues, coughing, chest discomfort, etc. It is harmful to plants, attacks rubber, reduces durability and appearance of paint and causes fabric dyes to fade. The amount of ozone is less in the regions closer to the equator.

Chlorofluorocarbons (CFCs), used as refrigerants in air conditioning and in aerosol sprays, gradually fly away up into the stratosphere, where they are subjected to ultraviolet radiation generating Cl^– free radicals. These radicals in turn destroy the O₃ molecules forming ordinary oxygen O₂ and again become free again, i.e., Cl^–. This continues and goes a long way. A single chloride ion can destroy up to 100,000 ozone molecules.

Smoke Causing Air Pollution

Smoke is a general name for dispersion of exceedingly fine particles of solids through gas. Technically, the term smoke is often applied to mists which are dispersion of fine particles of liquids. Smoke is usually emitted whenever incomplete combustion of organic material takes place, the particles consisting of coal and tar. The production of smoke represents a waste of combustible matter, quite apart from the nuisance it causes. It is not possible to prevent altogether the emission of smoke when boilers are fired with coal.

Conclusion of Essay on causes of air pollution

Air pollution remains a critical global issue driven by human activities. All stakeholders should put forward their efforts and by addressing the core issues we can reduce air pollution.

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