Agricultural lands in the country provide food stuffs for the city. As the most urbanized, industrialized and affluent city in the country, Santiago is faced with many problems typical of large urban areas, namely environmental pollution. Both industry and vehicles contribute to the severe environmental problems of the city. Air pollution in the metropolitan area of Santiago is a source of great concern, since the city is located in a valley whose geographic characteristics are unfavourable for the dispersal of air pollutants. In an effort to reduce air pollution, the city authorities have restricted the operation of motor vehicles, keeping one fifth of all vehicles off the streets each weekday.
Public transportation is provided by a subway and bus system.
The collection, hauling and final disposal of solid wastes is reported to have improved greatly in recent years. The city has a well-designed sewage system which conveys water by means of the main sewer to the River Mapocho. However, there are no sewage treatment plants, and both the Mapocho and Aipo Rivers are badly polluted with urban sewage and industrial waste water. A Special Commission for the Decontamination of the Metropolitan Region has been established to address these environmental issues. The Government of Chile now seeks a programme of decentralization for Santiago due to its rapid and high growth rates.