In particular, the recent increase in the number of automobiles has resulted in a considerable amount of exhaust gas being mixed with the air.
Car exhaust contains many chemicals such as sulfur oxides and nitrogen oxides, which are produced when gasoline and diesel fuel are burned. When these substances are mixed with rainwater, the rain becomes acidic. This is acid rain. Acid rain is called acid rain because it is acidic.
When acid rain falls for a long period of time, it has a variety of negative effects, including tree damage, fish death in rivers and lakes, and brittle concrete. This is a very serious problem for the future environment.