There are a lot of problems facing people on the Earth: the growth of the world population, economic crisis, ethnic conflicts, etc. But the most urgent problem concerning the people of the whole world is the ecological one.
Ecology is the science that studies the conditions of the habitation of the man, animals and plants for the benefit of present and future generations. The Earth is our home and we must do our best to reduce the pollution.
And where does the pollution come from? It comes from plants, factories, from big cities, from big machines such as lorries, trunks, big ships and airplanes. Megalopolises are full of lorries, buses, cars. Every car is a little factory but there are millions of them and they pollute the air in the cities. Factories and plants are the main sources of pollution. They pollute air with fume, harmful and poisonous substances. Their chimneys release thousands of tons of soot. They pollute water too. They release chemical and industrial substances and it influences harmfully flora and fauna of the rivers and the seas in which rivers bring their water.
People pollute environment with garbage, litter, tins, paper. Ships which transport oil sometimes meet with an accident and oil covers water. Some rivers are dead completely. Near such rivers the land is dead. And there is no fish in them.
And the greatest threat of life on Earth is a nuclear weapon. Preserving peace remains the most urgent task facing mankind. These all processes are the reasons of pollution of the environment. The sky is covered with soot and dirt, so it's hard to breath.
There is great noise pollution in great industrial and economical centers. If pollution grows, we'll die. That's why we must develop and improve new technologies and find some ways to use wastes as raw material. We must do our best to stop nuclear tests by all nations. In short we must fight with all kinds of pollution.