An unstable balance
We have seen that atmospheric pollution derives from a series of substances that are produced by one or more ‘sources’ (industries, cars and others). Luckily, after a more or less long time spent in the atmosphere, nature can “remove” a certain amount of it. For instance, the carbon dioxide produced by the combustion of fossil fuels and by the breathing of animal and vegetal living organisms is absorbed not only by the vegetation (through the photosynthesis), but is also largely counteracted by seawater, that can fix it through the phytoplankton and stabilise it in carbonated sedimentary rocks. The composition of the atmosphere is therefore in a state of dynamic balance, whose stability depends on the ability of these ‘self-depuration’ processes to counteract or at least reduce the negative effects of man’s activities. The problem arises when the amounts of pollutants emitted in the atmosphere exceed its “self-depurating” ability, increase their concentrations in the air and reach limits that are harmful to man and to nature. In this case, the development model of man and of a country may be no longer “sustainable” in the long term.
Ecologic research is more and more oriented towards an...