People have always polluted their enviroment. But until now pollution was not such a serious problem. People lived in uncrowned areas and did not have pollution — causing machines. With the development of crowded industrial cities which put huge amounts of pollutants into small areas, the problem has become more important. Cars and other new inventions make pollution steadily worse. Since the late 1960's people have become anxious about the danger of pollution. Clean air, water, and soil are necessary for living. But polluted air can cause illness, and even death. Polluted water kills fish and other marine life. On polluted soil, food can not be grown. In addition environmental pollution spoils the natural beauty of our planet. Pollution is as complicated as serious problem. Automobiles are polluting the air but they provide transportation for the people. Factories pollute the air and the water but they provide jobs for people and produce necessary goods. People would have to stop using many useful things if they wanted to end pollution immediately. Scientists and engineers can find the ways to reduce pollution from automobiles and factories. Government can pass the laws for reducing of pollution. Individuals and groups of people can work together to stop pollution. Every year world industry pollutes the atmosphere with about 1000 million tons of dust and other harmful substances. Many cities suffer from smog. Vast forests are cut and burn in fire. Their disappearance upsets the oxygen balance. As a result some rare species of animals, birds, fish and plants die forever, a number of rivers and lakes dry up.