Santiago - Environmental Issues

Environmental Issues

Thermal inversion (a meteorological phenomenon whereby a stable layer of warm air holds down colder air close to the ground) causes high levels of smog and air pollution to be trapped and concentrated within the Central Valley during winter months. In the 1990s air pollution fell by about one-third, but there has been little progress since 2000.

As of March 2007, only 61% of the wastewater in Santiago was treated, which increased up to 71% by the end of the same year. However, the Mapocho River, which crosses the city from the northeast to the southwest of the Central Valley, remains contaminated by household, agricultural, and industrial sewage, and by upstream copper-mining waste (there are a number of copper mines in the Andes east of Santiago), which is dumped unfiltered into the river. Laws require industry and local governments to process all their wastewater, but are loosely enforced. There are now a number of large wastewater processing and recycling plants under construction, and ongoing plans to decontaminate the river and make it navigable.

Noise levels on the main streets are high, mostly because of noisy diesel buses. Diesel trucks and buses are also major contributors to winter smog. A lengthy replacement process of the bus system that began in 2005 was scheduled to end in 2010. A major source of Santiago air pollution year-round is the smelter of the El Teniente copper mine. The government does not usually report it as being a local pollution source, as it is just outside the reporting area of the Santiago Metropolitan Region, being 110 kilometres (68 mi) from downtown.