Нужен перевод! «ecology» is a very popular word today. but what does it mean? ecology is a science which studies the relationships between all forms of life on our planet and the environment. this word came from the greek «oikos» which means «home». this idea of «home» includes our whole planet, its population, nature, animals, birds, fish, insects and all other living beings, and even the atmosphere around our planet. do all of them live a happy and healthy life in our common home nowadays? unfortunately not. since ancient times nature has served man giving him everything he needs: air to breathe, food to eat, water to drink, wood for building and fuel for heating his home. for thousands of years people lived in harmony with the environment and it seemed to them that the resources of nature had no end or limit. with the industrial revolution our negative influence on nature began to increase. large cities with thousands of steaming, polluting plants and factories can be found nowadays all over the world. the by-products of their activity pollute the air we breathe, the water we drink, the fields where our crops are grown. every year the atmosphere is polluted by about 1000 tons of industrial dust and other harmful substances. big cities suffer from smog. cars with their engines have become the main source of pollution in industrial countries. vast forests are cut down in africa, south america and asia for the needs of industries in europe and the usa. the loss of the forests upsets the oxygen balance of the new wastelands. as a result some species of animals, birds, fish and plants have disappeared and keep disappearing. rivers and lakes dry up. one of the most recent examples is the aral sea, which has become much smaller due to man's activity. the pollution of the air and the world's oceans and the thinning of the ozone layer are the other problems arising from man's careless attitude to ecology. the protection of the environment is a universal concern. active measures should be taken to create an international system of ecological security. some progress has been made in this direction. 159 countries — members of the united nations organisation — have set up environmental protection agencies. a lot of conferences have been held by these agencies to discuss ecological problems, some of which are of extreme urgency. in russia and the former soviet republics there are some areas where the environment is in a poor state. the aral sea, lake baikal, the kuzbass, semipalatinsk and chernobyl. for decades nuclear weapons were tested near semipalatinsk, and the ground is contaminated with radiation there. more than twenty years ago a pulp-and-paper factory was built on the shore of lake baikal. as a result of the pollution, more than 50 per cent of the world's purest water has been ruined. the whole ecological system of the lake has changed greatly. after the disaster in chernobyl the inhabitants of the nearby towns and villages had to be evacuated. some of them died and some have become invalids. ecological catastrophes do a lot of harm to nature, but they are much more dangerous for man. the question is whether mankind is going to live or die.