China is rapidly developing as evidenced by enhanced urbanization and industrialization and greatly increased energy consumption. However, these have brought Chinese cities a variety of urban air pollution problems in recent decades. During the 1970s, black smoke from stacks became the characteristic of Chinese industrial cities; in the 1980s, many southern cities began to suffer serious acid rain pollution; and recently, the air quality in large cities has deteriorated due to nitrous oxides (NOx), carbon monoxide (CO), and photochemical smog, which are typical of vehicle pollution. Some cities now have a mixture of these. Urban air pollution influences both the.