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People have always polluted their surroundings. But until now pollution was not such a serious problem. People lived in uncrowded rural 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. Automobiles and other new inventions make pollution steadily worse. Since the late 1960’s people have become alarmed with the danger of pollution.
Industrial Cities
Surroundings
People
The Danger of Pollution