The world itself is becoming much smaller by using modern traffic and TV, telephone and so on. Life today is much easier than it was hundreds of years ago, but it has also brought new problems. One of the biggest is pollution (污染). Pollution comes in many ways. We see it, smell it, drink it and even hear it.
The more people, the more pollution. Many years ago, the problem was not so serious because there were not so many people. Man is now slowly polluting the whole world.
Air pollution is still the most serious. It's bad to all living things in the world. Water pollution kills our fish and pollutes our drinking water. Noise pollution makes us become angry more easily.
Many countries are making rules to fight pollution. They stop people from burning coal (煤) in houses and factories in the city.
The pollution of SO2 is now the most dangerous problem of air pollution. It is caused by heavy traffic. It is sure that if there are fewer people driving, there will be less air pollution.