Air Pollution Essay: A Comprehensive Overview

     Though people progress toward civilization with the benefit of science and technology,  humans face a dire crisis. One such problem is environmental pollution. The environment of the past was pure but with the progress of civilization, three important resources of nature - water, air, and soil are heavily polluted by natural causes such as wildfowling, eruptions, and man-made causes such as forest destruction, increasing population, a larger number of factories, etc.

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     If the concentration of solid waste materials or unnecessary particles or gaseous substances,  arising from various natural or man-made causes, decreases or increases from the normal ratio in the air, then that type of air is called polluted air and that method is called air pollution.

Causes of Air pollution:

(i) Greenhouse gases: Greenhouse gases such as nitrous oxide (N₂O), carbon monoxide (CO), carbon dioxide (CO₂), methane (CH4), CFCs (chlorofluorocarbons), etc. cause air pollution.

(ii) SPM (Suspended Particulate Matter): It can be smoke, dust, or aerosol.  The carbon particles contained in the smoke emitted from vehicles or fossil fuels are less than 10 µm in size.  They float finely in the air and can remain in the air for weeks.  SPM is a particular cause of air pollution.

Effects of Air pollution:

(i) Acid rain and its effects: Acidic water mixes with the soil and kills microorganisms living in the soil.  It harms aquatic plants and animals when mixed with water. Chemicals such as SO2, and NO₂, produced from different factories, react with water particles in the atmosphere and they form H₂SO₄ and HNO3 acids and fall to the ground as rain.

 (i) SO2 + H2O → H2SO4;  SO3 + H2O = H2SO4,   (ii) 2NO2 + H2O → HNO3 + HNO2

Effects of acid rain: 

(a) Effects on soil: Acid rain is very damaging to soil.  Some microorganisms cannot tolerate the change in soil pH and die.  Under the influence of acid, the activators of microorganisms are inactivated. 

(b) Effects on forests and vegetation: Acid rain damages the soil as well as forests and vegetation. The leaves fall off and the trees wither.  Crops can be protected from acid rain by applying compost and lime.  Applying limestone to crops increases soil fertility and stabilizes pH levels.

(c) Effects on human health: Acid rain does not directly affect human health.  Rainwater contains very little acid.  Sulfur dioxide and nitrogen oxides are present in acid rain, when the levels of those elements increase, heart or lung trouble symptoms are seen in the human body.  Apart from that, the symptoms of asthma or bronchitis are also seen.

(d) Other adverse effects: Large buildings, and historical monuments, which are made of rock or limestone or marble or which have high calcium carbonate levels, are being damaged at an excessive rate due to acid rain.  Acids in rainwater react with calcium compounds to produce gypsum from rock.  

CaCO3(s) + H₂SO₄ CaSO4(s) + CO2(g) + H₂O(1)

(ii) Lung diseases: Air pollution causes diseases like asthma, emphysema, bronchitis, pneumonia, allergies etc.