Vocabulary

Scientists distinguish between natural and artificial sources of air pollution.

Natural pollution of the atmosphere occurs when volcanoes erupt, rock is weathered, dust storms take place, forest fires occur as a result of lightning, and sea salt is washed ashore. The atmosphere always contains aero plankton (bacteria, including those causing disease).

Artificial pollution of the atmosphere is characteristics mostly of cities and industrial districts. Cities and suburbs contain numerous industrial enterprises, automobiles and heating system which pollute the air and negatively influence the local climate. It has been established that air pollution in urban areas grows in proportion to the population.

For a long time the problem of air pollution in the cities was mainly connected with coal-burning in heating system which emitted smoke, ashes and sulphureous gas (SO₂). Today industrial enterprises and automobiles are the main sources of atmospheric pollution.

Industry pollutes the air by emissions of harmful gases and industrial dust. Thermal electric plants, metallurgical and chemical factories, oil refineries, cement and other plants are sources of air pollution. The chemical composition of emissions into the atmosphere is different. It depends on the kind of fuel, raw materials, technology, etc.

Today the biggest polluter is the car. Exhaust fumes are the main cause of bad air quality, which can make people feel ill and have difficulty breathing. It is estimated that one car burns up the amount of fresh air needed for 100 adults to breathe. This problem is especially bad in some cities where, on days when there is not much wind, a brown layer of smog hangs in the air. The number of cars is increasing every year, and this causes serious congestion and traffic jams on the roads. Governments then build new roads trying to improve the situation, but this means that they cut down trees and destroy more of the countryside.

City air is polluted not only by exhaust fumes but also by the products of their oxidation, often more toxic than the initial substance. One of them is ozone which is useful in small quantities, but it is extremely poisonous in large concentrations.

The problem of radioactive pollution of the air arose in 1945 after the atomic bombs were dropped on the Japanese cities of Hiroshima and Nagasaki. Since then atomic weapons have become much more powerful and have been stockpiled in large quantities.

When an atom bomb explodes, an extremely high level of radiation covers an enormous area for a long period of time as the radioactive particles are dispersed. Radioactive products fall on the earth, polluting the soil, water bodies and living things. Finely dispersed dust is carried many thousands of kilometers away and causes global radioactive pollution of the air. Radioactive elements are very harmful to living things and cause hard diseases.

Поиск по сайту: