A
Air pollution is one of the most common types of pollution in the world nowadays. It is quite serious in many places, especially in big cities. It can do great harm to our environment such as making the earth warmer, causing acid rain or destroying the ozone layer. As for human beings, air pollution causes all kinds of breathing problems.
There are several reasons for air pollution. Firstly, many cities have a lot of factories and there we need to make food, clothing and other things. Every year these factories pour millions of tons of smog into air. Secondly, power factories can also give out harmful air. For example, in 1986 there was a bad accident at a nuclear power station in Russia. A cloud of radiation crossed the whole Europe. It is said that 125,000 people died in Russia as a result of illnesses caused by this accident. Thirdly, there are more cars in cities now. Once they are out in the streets, they will take in fresh air and give out dirty gas. Besides, smoking cigarettes also makes air pollution worse as will as damaging(损害) our health.
