million square kilometers. They are cut down rapidly. Nobody knows exactly how much of this resource is cut down every year.
2. When we think of wildlife facing extinction, we are usually thinking of large animals such as whales, elephants and rhinos. These creatures are indeed under risk of extinction because of cruel hunting.
3. The lower part of the stratosphere contains a band of warm gas called the ozone layer. Ozone absorbs very shortwave ultraviolet radiation — that is the harmful, burning rays from the Sun. These rays kill plants and cause burns, skin cancer and cataracts in animals and people.
4. Smog is very bad for health. In the famous London smog of 1952 about 4000 people died in two weeks from chest diseases such as bronchitis and pneumonia.
5. The Mediterranean Sea occupies 1 percent of the world`s water surface. Sixteen countries border on the Mediterranean. Almost all of them regularly dump shiploads of industrial waste a few miles off shore.
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