The term pollution is derived from the Latin word pollutioneum meaning ‘make dirty’.
Rapid and unplanned industrialization, urbanization, deforestation cause the release of a variety of extraneous materials (inorganic, organic, biological or radiological) and energy into the environment in a continuous and uninterrupted manner.
When the concentration of such materials exceeds the threshold limit, the environment becomes partially or totally unsuitable for living organisms.
This is known as environmental pollution. The concentration of the extraneous materials becomes so high that the eco-system is unable to either neutralize or disperse them and they get accumulated.
Pollution can thus be defined as ‘an undesirable change in physical, chemical and biological characteristics of air, water and soil due to anthropogenic activities, which may harmfully affect the life or create a potential health hazard to all living organisms in the biosphere’. The extraneous materials and energy that cause pollution are termed as ‘pollutants’.
Sometimes the term ‘contaminant’ is used along with ‘pollutant’. Pollutants are generally considered as substances that occur in nature in greater amount than natural abundance are caused by human activities and have a detrimental effect on all living organisms, e.g., Pb, Hg, NOx, whereas contaminants are substances which do not occur naturally but are introduced by human activities into the environment, affecting its composition. They may or may not have detrimental effect, e.g., MIC (methyl isocyanine, CH3-N=C=0). A contaminant is considered to be a pollutant only when it has any detrimental effect.
Environmental pollution is the most important agent causing environmental degradation. They have a cause-effect relationship- pollution being the cause and degradation, the effect.