Concept of Environmental Purity
Pollution occurs when an excess of a substance generated by human activity is present in the wrong environmental location. With our view of the physical environment as a combination of the solid land, the waters held by the land and the gases atmosphere above, an examination of the effects of chemicals on the environment can be made. Any culpable variation in the allowable percentage of ingredients make the environment “polluted”. The concept of pollution has many aspects, some are emotional, some rigorous and some simply hard and difficult to pin down with any precision. The standards of purity for the limits of contamination permitted are legal aspects set by human societies. Yet these laws are subjective, as these are considerable variations in the observance and acceptance of these rules and regulations from palace to place, time to time and individual to individual.
What is purity of our environment? We generally use the term pure water to drink and pure air to breathe. We mean the water or air is ‘uncontaminated’ by any other substance. There is not a single drop of truly pure water in the entire lithosphere, hydrosphere or atmosphere. Even the ‘purest’ rain water is not pure al all. Is contains the dissolved atmospheric gases. The water from the well or the spring is also not pure. They contain dissolved salts of minerals present in the ground. And the ‘air’ also is not pure. Apart from the general ingredients, the atmospheric air contains water vapour and is contaminated by lightening and other natural phenomenon and by volatile organic compounds produced by animals and plants.
Thus the concept of environmental purity means the air and water must be
1. wholesome and pleasant and
2. free of disease causing chemicals and biological organisms.
Thus pollution becomes an aesthetic as well as scientific topic. The definition of pollution has two more important implications. First, we cannot label any chemical as pollutants unless we specify where it is. What counts in the environmental pollution is the combination of substance and location. Consider the case of ozone and chlorofluorocarbons. Ozone is an irritating, toxic gas. In the troposphere, the region which holds the air we breathe, ozone is a pollutant. Many kilometers higher, in the stratosphere, ozone becomes a life saving gas as it protects us from effects of ultra violet radiation. Chlorofluorocarbons on the other hand, are nonflammable gases with little toxicity, little odour and little chemical reactivity. In the troposphere they are virtually harmless. But up in the stratosphere they become ozone-destroying pollutants.
Secondly, pollution implies the degradation of the environment due to the human activities rather than due to the natural events beyond our control. Studies show that life has existed on earth for several billion years. Plants and animals resembling those we see on earth today have been around for several million years. But the discharge of chemicals into the environment by humans, on an industrial scale, has been going on for only a few hundreds years.
There had been periodic catastrophes such as volcanic eruptions, floods and forest fires ignited by lighting. Yet this planet survived all such calamities and both plant and animal life can continue to exist on earth and survive repetitions of these events. But look at the devastating effects of the discharge of chemical masses dumped into the environment by human activities. Comparing the effects of million of years of natural calamities and the few hundred years’ human activity, pollution is what which related to human activity alone.